阅读说明：本技术 一种具有多重安保功能的低速机高压共轨系统 (Low-speed machine high pressure common rail system with multiple security functions ) 是由 涂天华 刘惠娥 张鹏 刘洋 侯旭洪 陈超 林小雪 张朝磊 于 2019-11-08 设计创作，主要内容包括：本方案提供了一种具有多重安保功能的低速机高压共轨系统,以实现高压共轨系统的多重安保功能。该系统包括：ECU,电控高压油泵,其内设置有电控比例阀,电控比例阀用于根据ECU的第一指令对从低速机的油箱进入电控高压油泵的低压重油进行进油比例调节；与电控高压油泵通过第一高压油管连接的第一分配块；与第一分配块通过第二高压油管连接的第二分配块；与第二分配块通过第三高压油管连接的共轨管；共轨管上安装有传感器,传感器和ECU连接；共轨管上安装有多个限流阀组件,每一个限流阀组件分别通过一根第四高压油管连接一支电控喷油器；共轨管上还安装有限压阀组件；第一分配块上装配有切断阀组件和安全阀组件；共轨管上以及每只电控喷油器上还安装有循环阀组件。(The scheme provides a low-speed machine high-pressure common rail system with multiple security functions to realize the multiple security functions of the high-pressure common rail system. The system comprises: the electronic control proportional valve is used for carrying out oil inlet proportion adjustment on low-pressure heavy oil entering the electronic control high-pressure oil pump from an oil tank of the low-speed machine according to a first instruction of the ECU; the first distribution block is connected with the electric control high-pressure oil pump through a first high-pressure oil pipe; the second distribution block is connected with the first distribution block through a second high-pressure oil pipe; the common rail pipe is connected with the second distribution block through a third high-pressure oil pipe; a sensor is arranged on the common rail pipe and connected with the ECU; a plurality of flow limiting valve assemblies are mounted on the common rail pipe, and each flow limiting valve assembly is connected with one electric control oil injector through a fourth high-pressure oil pipe; the common rail pipe is also provided with a pressure limiting valve component; the first distribution block is provided with a cut-off valve assembly and a safety valve assembly; and a circulating valve assembly is also arranged on the common rail and each electric control fuel injector.)

1. A low-speed machine high pressure common rail system with multiple security functions is characterized by comprising: an ECU is provided with a plurality of sensors,

the device comprises an electric control high-pressure oil pump (1), wherein an electric control proportional valve (2) is arranged in the electric control high-pressure oil pump (1), and the electric control proportional valve (2) is used for carrying out oil inlet proportion adjustment on low-pressure heavy oil entering the electric control high-pressure oil pump (1) from an oil tank of a low-speed machine according to a first instruction of an ECU (electronic control unit);

the first distribution block (6) is connected with the electric control high-pressure oil pump (1) through a first high-pressure oil pipe (3);

a second distribution block (9) connected with the first distribution block (6) through a second high-pressure oil pipe (8);

a common rail pipe (12) connected to the second distribution block (9) via a third high pressure oil pipe (10);

a sensor (17) for detecting the fuel pressure of the high-pressure heavy oil of the common rail pipe (12) is arranged on the common rail pipe (12), and the sensor (17) is connected with an ECU (electronic control unit);

a plurality of flow limiting valve assemblies (13) are mounted on the common rail pipe (12), and each flow limiting valve assembly (13) is connected with one electric control oil injector (15) through a fourth high-pressure oil pipe (14); the restrictor valve assembly (13) is adapted to close when the difference in fuel pressure between the fourth high pressure conduit (14) and the common rail conduit (12) exceeds a set pressure differential value;

the common rail pipe (12) is also provided with a pressure limiting valve assembly (18), and the pressure limiting valve assembly (18) is used for opening when the fuel pressure in the common rail pipe (12) exceeds a first set pressure value, so that the fuel pressure in the common rail pipe (12) is stabilized to a target pressure value;

the first distribution block (6) is provided with a cut-off valve assembly (5) and a safety valve assembly (7); the cut-off valve assembly (5) is used for carrying out pressure relief treatment according to a second instruction of the ECU; the safety valve assembly (7) is used for opening when the cut-off valve assembly (5) and the pressure limiting valve assembly (18) fail and the fuel pressure in the common rail pipe (12) exceeds a second set pressure value;

and circulating valve assemblies (16) are further mounted on the common rail pipe (12) and the electric control fuel injector (15), and the circulating valve assemblies (16) are opened when the low-speed engine is stopped, so that circulating loops are formed between the common rail pipe (12) and the electric control fuel injector (15) and a fuel tank of the low-speed engine respectively.

2. The system according to claim 1, characterized in that said electrically controlled high-pressure oil pump (1) comprises:

the pump body (101), the pump body (101) is provided with a middle hole along the axial direction;

a pump cover (102), the pump cover (102) being attached to an upper end surface of the pump body (101);

the oil inlet and outlet valve assembly (103), the plunger matching part (104), the plunger spring (105), the lower spring seat assembly (106) and the guide piston assembly (107) are all assembled in a central hole of the pump body (101);

the electric control proportional valve (2) is assembled on the side surface of the pump body (101);

the oil inlet and outlet valve assembly (103) comprises: an oil inlet valve assembly (1031) and an oil outlet valve assembly (1032);

the oil feed valve assembly (1031) includes: the oil inlet valve comprises an oil inlet valve seat (10311), an oil inlet valve (10312) and an oil inlet valve spring (10313);

the oil inlet valve (10312) is mounted in a central hole of the oil inlet valve seat (10311); the oil inlet valve spring (10313) is limited between the oil inlet valve (10312) and the hole wall of the oil inlet valve seat (10311); under the compression of the oil inlet valve spring (10313), the oil inlet valve (10312) and the oil inlet valve seat (10311) form a conical surface seal;

the oil outlet valve assembly (1032) includes: an oil outlet valve seat (10321), an oil outlet valve (10322), an oil outlet valve spring (10323) and an oil outlet valve spring seat (10324);

the oil outlet valve spring seat (10324) is installed at the upper end of the oil outlet valve seat (10321); the oil outlet valve (10322) is installed in a middle hole of the oil outlet valve seat (10321); the oil outlet valve spring (10323) is limited between the oil outlet valve (10322) and the oil outlet valve spring seat (10324); the oil outlet valve (10322) and the oil outlet valve seat (10321) form a conical surface seal under the compression of the oil outlet valve spring (10323);

a high-pressure oil outlet cavity (1033) is formed between the oil outlet valve seat (10321) and the oil inlet valve seat (10311);

a high-pressure oil chamber (1041) is formed in the plunger and barrel assembly (104), and the high-pressure oil chamber (1041) is communicated with the high-pressure oil outlet chamber (1033) through an oil hole in the oil inlet valve seat (10311);

the electric control proportional valve (2) is communicated with an oil inlet hole of the oil inlet valve seat (10311) through an oil hole in the pump body (101), and the oil inlet hole is communicated with or disconnected from the high-pressure oil chamber (1041);

and a cooling circulation oil passage is arranged on the electric control proportional valve (2), and cooling oil from the cooling oil passage of the pump body (101) flows back to the cooling oil passage of the pump body (101) after being injected into the cooling circulation oil passage.

3. The system of claim 2, wherein the plunger and barrel assembly (104) comprises:

a plunger sleeve (1042) arranged at the lower end of the oil inlet valve seat (10311);

a plunger (1043) slidably inserted into the central hole of the plunger sleeve (1042), the plunger (1043) and the oil inlet valve seat (10311) together forming the high-pressure oil chamber (1041);

the inner wall of the plunger sleeve (1042) is provided with a first ring groove (10421) and a second ring groove (10422);

a mixed oil outlet channel and a lubricating oil channel (1012) are arranged on the pump body (101), the mixed oil outlet channel is communicated with the first annular groove (10421) through a mixed oil channel (10423) on the plunger sleeve (1042), and the lubricating oil channel (1012) is communicated with the second annular groove (10422) through a lubricating oil channel (10424) on the plunger sleeve (1042);

the first ring groove (10421) is located above the second ring groove (10422); the lower spring seat assembly (106) is arranged below the plunger and barrel assembly (104), and the lower spring seat assembly (106) comprises:

the outer spring seat (1061) is of a boss type structure with a thin outer side and a thick middle part, and a third counter bore (10611) which is a concave spherical surface is formed in the upper end surface of the outer spring seat (1061);

an upper sphere (1062), the lower part of which is installed in the third counter bore (10611), and the lower end surface of the upper sphere (1062) is provided with a convex spherical surface matched with the concave spherical surface;

the inner spring seat (1063) is sleeved on the upper part of the upper ball body (1062), and the inner spring seat (1063) is provided with a first axial through hole (10631) penetrating through the upper end surface and the lower end surface;

the lower cylindrical head (10431) of the plunger (1043) is limited in the first axial through hole (10631), and the lower end face of the lower cylindrical head (10431) of the plunger (1043) is abutted to the upper end face of the upper sphere (1062).

4. The system of claim 3,

a spherical hole (10612) is formed in the center of the third counter bore (10611), a third ring groove (10613) is formed in the lower end surface of the outer spring seat (1061), and the spherical hole (10612) is communicated with the third ring groove (10613) through a lubricating oil inlet pipeline (10614);

the outer surface of the outer spring seat (1061) forms a conical surface, the conical surface is provided with a lubricating oil outlet channel (10615), and the lubricating oil outlet channel (10615) is communicated with the lower end surface of the outer spring seat (1061); the lubricating oil outlet channel (10615) is obliquely arranged;

a circumferential ring groove (10621) is formed in the circumferential direction of the upper sphere (1062);

a positioning pin (1064) is installed in the circumferential groove (10621) after passing through a positioning pin hole (10616) of the outer spring seat (1061);

the distance between the upper surface and the lower surface of the circumferential ring groove (10621) is larger than the diameter of a cylinder of the part of the positioning pin (1064) positioned in the circumferential ring groove (10621);

the first axial through hole (10631) arranged inside the inner spring seat (1063) comprises:

a seventh hole (10632), an eighth hole (10633) and a ninth hole (10634) with diameters gradually increasing from top to bottom;

a first guide hole (10635) with gradually increasing diameter is arranged between the eighth hole (10633) and the ninth hole (10634);

a second guide hole (10636) with a gradually increasing diameter is arranged at one side of the ninth hole (10634) facing the upper sphere (1062);

the hole walls of the first guide hole (10635) and the second guide hole (10636) are formed into guide tapered surfaces (10637);

the upper part of the upper sphere (1062) is partially positioned in the ninth hole (10634) through the second guide hole (10636);

a gap which is larger than or equal to 1mm is arranged between the upper sphere (1062) and the ninth hole (10634);

and a gap which is larger than or equal to 1mm is formed between the third counter bore (10611) and the upper sphere (1062).

5. The system of claim 2, wherein the pilot piston assembly (107) comprises:

a guide piston (1071) provided with a first mounting hole (10711) at the center of the upper end surface thereof; a second mounting hole (10712) is formed in the lower end face of the lower spring seat assembly, the first mounting hole (10711) is communicated with the second mounting hole (10712) through a communication hole (10713), and the lower spring seat assembly (106) is mounted in the first mounting hole (10711);

a roller assembly (1072) comprising: a roller (10728) mounted in the second mounting hole (10712), a roller bush (10722) interference-fitted in the roller (10728), and thrust bearings (10723) interference-fitted at both axial ends of the roller (10728); a ring groove (10724) is formed in the axial direction of the roller (10728), and arc transitional connection is formed between the groove bottom of the ring groove (10724) and the axial end face of the roller (10728);

a roller pin (1073) which is clearance fitted within the roller bushing (10722);

a boss (10714) is arranged on the hole wall of the second mounting hole (10712) in a protruding mode, and the boss (10714) is in contact with the thrust bearing (10723);

the boss (10714) is uniformly arranged with a plurality of first radial oil grooves (10715) in a radial direction, the first radial oil grooves (10715) being provided with respect to the thrust bearing (10723).

6. The system of claim 5,

the outer surface of the roller pin (1073) is a cylindrical surface, two-step kidney-shaped grooves (10731, 10732) are respectively arranged at two positions on the cylindrical surface, and the kidney-shaped grooves (10731, 10732) are arranged at the middle position of the roller pin (1073);

a small-angle wedge-shaped groove with an angle of 5-20 degrees is formed between the outer-layer kidney-shaped groove (10731) and the outer surface of the roller bushing (10722), and oil holes (10733, 10734) are formed in the inner-layer kidney-shaped groove (10732);

the two oil holes (10733, 10734) at the two positions are communicated through a lubricating oil outlet channel, and the two oil holes (10733, 10734) are arranged at an angle of 70-120 degrees;

the outer surface of the guide piston (1071) is a cylindrical surface, a plurality of circumferential oil grooves (10729, 10725), a first axial oil groove (10716) and a vertical groove (10717) are arranged on the cylindrical surface, the vertical groove (10717) is arranged in the circumferential oil groove (10725), and the vertical groove (10717) is communicated with the circumferential oil groove (10729) through the first axial oil groove (10716);

an inclined hole (10718) is further formed in the cylindrical surface, and two ends of the inclined hole (10718) are respectively communicated with the circumferential oil groove (10725) and the inner wall of the second mounting hole (10712);

a second axial oil groove (10719) communicated with the circumferential oil groove (10725) is further arranged on the cylindrical surface;

the cylindrical surface is also provided with a first straight hole (10720) and a second straight hole (10721) which are connected, the first straight hole (10720) is communicated with the first axial oil groove (10716), and the second straight hole (10721) is communicated with the first mounting hole (10711);

and a lubricating oil inlet channel (10735) is arranged on the outer circular surface of the roller pin (1073), the lubricating oil inlet channel (10735) is arranged relative to the inclined hole (10718), and the lubricating oil inlet channel (10735) is communicated with the lubricating oil outlet channel.

7. The system of claim 1,

the common rail pipe (12) is provided with an oil inlet pipeline (1201) and an oil return pipeline (1202) which penetrate through two ends;

an oil inlet end cover (121) is fixed at one end of the common rail pipe (12), and an oil inlet communicated with the oil inlet pipeline (1201) is formed in the oil inlet end cover (121);

an end cover (122) is fixed at the other end of the common rail pipe (12), an oil outlet communicated with the oil inlet pipeline (1201) is formed in the end cover (122), and the circulating valve assembly (16) is fixed on the end cover (122);

the pressure limiting valve assembly (18) and the plurality of flow limiting valve assemblies (13) are respectively communicated with the oil inlet pipeline (1201), and the pressure limiting valve assembly (18) and the plurality of flow limiting valve assemblies (13) are respectively communicated with the oil return pipeline (1202).

8. The system of claim 7, wherein the circulation valve assembly (16) comprises:

a first valve body (161) fixed on the end cover (122), wherein the lower end surface of the first valve body is provided with a first middle hole (1601) communicated with the oil outlet, the upper end surface of the first valve body is provided with a second middle hole (1602), and the first middle hole (1601) is communicated with the second middle hole (1602);

a first spool (162) slidably inserted into the first center hole (1601) from a lower end surface of the first valve body (161) and partially located in the second center hole (1602);

a lower spring seat (164) which is sleeved on the part of the first valve core (162) positioned in the second middle hole (1602) and is fixedly connected with the first valve core (162); a first cavity is formed between the lower spring seat (164) and the bottom of the second central bore (1602);

a gland (167) fixed to an upper end surface of the first valve body (161), the gland (167) having a threaded hole (1603) opened in the upper end surface;

an oil return joint (168) partially fixed in the threaded hole (1603);

a first pressure regulating spring (169) that is retained between the lower spring seat (164) and the gland (167);

a first oil return passage (1605) communicated with the first middle hole (1601) is arranged on the first valve body (161), a second oil return passage (1606) communicated with the first oil return passage (1605) is arranged on the gland (167), a third oil return passage (1607) communicated with the second oil return passage (1606) is arranged on the oil return joint (168), and the first oil return passage (1605), the second oil return passage (1606) and the third oil return passage (1607) form a circulating oil passage;

a first air inlet channel (1608) communicated with the first cavity is arranged on the first valve body (161), a second air inlet channel (1629) communicated with the first air inlet channel (1608) and an air inlet (1630) communicated with the second air inlet channel (1629) are arranged on the gland (167);

the spring force of the first pressure regulating spring (169) is smaller than or equal to the gas pressure introduced into the first cavity and the pressure of the oil inlet pressure at the oil inlet end of the first middle hole (1601) sum, the first valve core (162) and the first middle hole (1601) form a conical surface seal therebetween, and the position where the conical surface seal is formed is located below the connecting position of the first oil return passage (1605) and the first middle hole (1601).

9. The system of claim 1, wherein the restrictor valve assembly (13) comprises: a valve seat (131) used for being connected with the high-pressure common rail, a second valve body (132), a second valve core (133) and a second pressure regulating spring (135),

the valve seat (131) is provided with a first oil inlet hole (13101) communicated with the high-pressure common rail;

the second valve body (132) has a second axial through hole (13209) penetrating through both upper and lower end surfaces thereof, and the valve seat (131) is press-fitted into the second axial through hole (13209) from a lower end surface portion of the second valve body (132);

the second valve core (133) is installed in the second axial through hole (13209) and is arranged above the valve seat (131);

the second valve core (133) is provided with an axial blind hole (13302) communicated with the first oil inlet hole (13101), and a cavity is formed between the upper end of the second valve core (133) and the second axial through hole (13209);

a transverse throttle hole (13304) which is communicated with the axial blind hole (13302) and the cavity is arranged in the second valve core (133);

the second pressure regulating spring (135) is sleeved on the second valve core (133) and is limited in the cavity;

the head part of the upper end of the second valve core (133) is provided with a third sealing conical surface (13305) and a fourth sealing conical surface (13306) which are connected;

the wall of the second axial through hole (13209) is formed with a first seal seat surface (13206) that can form a conical surface seal with the third seal conical surface (13305), and the first seal seat surface (13206) can form a gap with the fourth seal conical surface (13306).

10. The system of claim 1, wherein the pressure limiting valve assembly (18) comprises: a third valve body (181), a third valve core (182), a third pressure regulating spring (185) and an oil pipe joint (186),

a first-stage hole (18101), a second-stage hole (18102), a third-stage hole (18104) and a fourth-stage hole (18105) which are communicated in sequence are formed in the third valve body (181) from bottom to top;

the head of the third valve core (182) is slidably inserted from the fourth stage hole (18105) and partially positioned in the second stage hole (18102) after passing through the third stage hole (18104), and the third valve core (182) can form a conical surface seal with the second stage hole (18102);

a first clearance for fuel to pass is formed between the third valve core (182) and the third-stage hole (18104), and a second clearance for fuel to pass is formed between the third valve core (182) and the fourth-stage hole (18105);

the oil pipe joint (186) is fixed at the upper end of the third valve body (181), a first counter bore (18601), a second counter bore (18602) and an oil outlet (18603) which are sequentially communicated are arranged in the oil pipe joint (186) from bottom to top, and the third pressure regulating spring (185) is limited between the third valve core (182) and the second counter bore (18602).

Technical Field

The invention relates to the field of high-pressure common rail systems, in particular to a low-speed machine high-pressure common rail system with multiple security functions.

Background

With stricter emission regulations and increased energy crisis, the high pressure common rail system is increasingly used in the diesel fuel system. The high-pressure common rail system has the characteristics of high injection pressure, high response speed, flexible control and the like, and meets increasingly strict emission regulations and requirements of users on fuel economy and emission performance. Different from a traditional mechanical fuel injection system, the high-pressure common rail system is always in a high-pressure state, and the requirements of the high-pressure common rail system on the reliability, safety and the like of parts are very strict.

Disclosure of Invention

The invention aims to provide a low-speed machine high-pressure common rail system with multiple security functions, so as to realize the multiple security functions of the high-pressure common rail system.

The invention provides a low-speed machine high-pressure common rail system with multiple security functions, which comprises: an ECU is provided with a plurality of sensors,

the electronic control high-pressure oil pump is internally provided with an electronic control proportional valve, and the electronic control proportional valve is used for carrying out oil inlet proportion adjustment on low-pressure heavy oil entering the electronic control high-pressure oil pump from an oil tank of the low-speed machine according to a first instruction of an ECU (electronic control Unit); the first distribution block is connected with the electric control high-pressure oil pump through a first high-pressure oil pipe; the second distribution block is connected with the first distribution block through a second high-pressure oil pipe; the common rail pipe is connected with the second distribution block through a third high-pressure oil pipe; the common rail pipe is provided with a sensor for detecting the fuel pressure of the high-pressure heavy oil of the common rail pipe, and the sensor is connected with the ECU; a plurality of flow-limiting valve assemblies are mounted on the common rail pipe, and each flow-limiting valve assembly is connected with one electric control oil injector through a fourth high-pressure oil pipe; the flow-limiting valve assembly is used for closing when the fuel pressure difference between the fourth high-pressure fuel pipe and the common rail pipe exceeds a set pressure difference value; the common rail pipe is also provided with a pressure limiting valve assembly, and the pressure limiting valve assembly is used for opening when the fuel pressure in the common rail pipe exceeds a first set pressure value, so that the fuel pressure in the common rail pipe is stabilized to a target pressure value; the first distribution block is provided with a cut-off valve assembly and a safety valve assembly; the cut-off valve assembly is used for performing pressure relief treatment according to a second instruction of the ECU; the safety valve assembly is used for opening when the cut-off valve assembly and the pressure limiting valve assembly fail and the fuel pressure in the common rail pipe exceeds a second set pressure value; and circulating valve assemblies are further mounted on the common rail pipe and the electric control oil injector and are used for being opened when the low-speed machine stops, so that circulating loops are formed among the common rail pipe, the electric control oil injector and an oil tank of the low-speed machine respectively.

Preferably, the electrically controlled high-pressure oil pump includes: the pump body is provided with a middle hole along the axis direction; the pump cover is arranged on the upper end face of the pump body; the oil inlet and outlet valve assembly, the plunger matching part, the plunger spring, the lower spring seat assembly and the guide piston assembly are all assembled in a middle hole of the pump body; the electric control proportional valve is assembled on the side surface of the pump body; the oil inlet and outlet valve assembly comprises: an oil inlet valve assembly and an oil outlet valve assembly; the oil feed valve assembly comprises: the oil inlet valve seat, the oil inlet valve and the oil inlet valve spring; the oil inlet valve is arranged in a middle hole of the oil inlet valve seat; the oil inlet valve spring is limited between the oil inlet valve and the hole wall of the oil inlet valve seat; under the compression of the oil inlet valve spring, the oil inlet valve and the oil inlet valve seat form conical surface sealing; the delivery valve assembly comprises: the oil outlet valve seat, the oil outlet valve spring and the oil outlet valve spring seat; the oil outlet valve spring seat is arranged at the upper end of the oil outlet valve seat; the oil outlet valve is arranged in a middle hole of the oil outlet valve seat; the oil outlet valve spring is limited between the oil outlet valve and the oil outlet valve spring seat; under the compression of the oil outlet valve spring, the oil outlet valve and the oil outlet valve seat form conical surface sealing; a high-pressure oil outlet cavity is formed between the oil outlet valve seat and the oil inlet valve seat; a high-pressure oil cavity is formed in the plunger and barrel assembly and is communicated with the high-pressure oil outlet cavity through an oil hole in the oil inlet valve seat; the electric control proportional valve is communicated with an oil inlet hole of the oil inlet valve seat through an oil hole in the pump body, and the oil inlet hole is communicated with or disconnected from the high-pressure oil cavity; and the electric control proportional valve is provided with a cooling circulation oil passage, and cooling oil from the cooling oil passage of the pump body flows back to the cooling oil passage of the pump body after being injected into the cooling circulation oil passage.

Preferably, the plunger and barrel assembly comprises: the plunger sleeve is arranged at the lower end of the oil inlet valve seat; the plunger is slidably inserted into the middle hole of the plunger sleeve, and the high-pressure oil cavity is formed among the plunger sleeve, the plunger and the oil inlet valve seat; the inner wall of the plunger sleeve is provided with a first ring groove and a second ring groove; the pump body is provided with a mixed oil outlet channel and a lubricating oil channel, the mixed oil outlet channel is communicated with the first annular groove through the mixed oil channel on the plunger sleeve, and the lubricating oil channel is communicated with the second annular groove through the lubricating oil channel on the plunger sleeve; the first ring groove is located above the second ring groove.

Preferably, the lower spring seat assembly is disposed below the plunger and barrel assembly, and the lower spring seat assembly includes: the outer spring seat is of a boss type structure with a thin outer side and a thick middle part, and a third counter bore which is a concave spherical surface is formed in the upper end surface of the outer spring seat; the lower part of the upper ball body is installed in the third counter bore, and the lower end face of the upper ball body is provided with a convex spherical surface matched with the concave spherical surface; the inner spring seat is sleeved on the upper part of the upper ball body and is provided with a first axial through hole penetrating through the upper end surface and the lower end surface; the lower cylindrical head of the plunger is limited in the first axial through hole, and the lower end face of the lower cylindrical head of the plunger is abutted to the upper end face of the upper ball body.

Preferably, a spherical hole is formed in the center of the third counter bore, a third ring groove is formed in the lower end surface of the outer spring seat, and the spherical hole is communicated with the third ring groove through a lubricating oil inlet pipeline; the outer surface of the outer spring seat forms a conical surface, the conical surface is provided with a lubricating oil outlet duct, and the lubricating oil outlet duct is communicated with the lower end surface of the outer spring seat; the lubricating oil outlet duct is obliquely arranged; a circumferential ring groove is formed in the circumferential direction of the upper sphere; the positioning pin penetrates through a positioning pin hole of the outer spring seat and then is installed in the circumferential ring groove; the distance between the upper surface and the lower surface of the circumferential ring groove is larger than the diameter of the cylinder of the part of the positioning pin, which is positioned in the circumferential ring groove.

Preferably, the first axial through hole provided inside the inner spring seat includes: a seventh hole, an eighth hole and a ninth hole, the diameters of which are gradually increased from top to bottom; a first guide hole with gradually increasing diameter is arranged between the eighth hole and the ninth hole; one side of the ninth hole facing the upper ball body is provided with a second guide hole with gradually increasing diameter; the hole walls of the first guide hole and the second guide hole are formed into guide conical surfaces; the upper part of the upper ball passes through the second guide hole part and is positioned in the ninth hole; a gap which is larger than or equal to 1mm is arranged between the upper ball body and the ninth hole; and a gap which is larger than or equal to 1mm is formed between the third counter bore and the upper ball body.

Preferably, the electrically controlled high-pressure oil pump further includes: the upper spring seat is sleeved on the plunger sleeve and is positioned at the upper end of the inner spring seat; the plunger spring includes: a first plunger spring that is press-fitted between the upper spring seat and the outer spring seat; a second plunger spring press-fitted between the upper spring seat and the inner spring seat.

Preferably, the diameters of the concave spherical surface in the outer spring seat and the convex spherical surface of the upper sphere are 20 to 100 times the diameter of the plunger.

Preferably, the pilot piston assembly comprises: the center position of the upper end surface of the guide piston is provided with a first mounting hole; a second mounting hole is formed in the lower end face of the lower spring seat assembly, the first mounting hole is communicated with the second mounting hole through a communication hole, and the lower spring seat assembly is mounted in the first mounting hole; a roller assembly comprising: the roller is arranged in the second mounting hole, the roller bushing is in interference fit in the roller, and the thrust bearings are in interference fit at the two axial ends of the roller; a ring groove is formed in the axial direction of the roller, and arc transition connection is formed between the groove bottom of the ring groove and the axial end face of the roller; a roller pin which is clearance fitted in the roller bushing; a boss is arranged on the hole wall of the second mounting hole in a protruding mode and is in contact with the thrust bearing;

the boss has a plurality of first radial oil grooves evenly arranged along radial direction, first radial oil groove for thrust bearing sets up. Preferably, the outer surface of the roller pin is a cylindrical surface, two positions on the cylindrical surface are respectively provided with two-step kidney-shaped grooves, and the kidney-shaped grooves are arranged in the middle of the roller pin; a small-angle wedge-shaped groove with an angle of 5-20 degrees is formed between the kidney-shaped groove positioned on the outer layer and the outer surface of the roller bushing, and an oil hole is formed in the kidney-shaped groove positioned on the inner layer; two oilholes of two positions department pass through lubricating oil outlet channel intercommunication, are 70 ~ 120 settings between two oilholes.

Preferably, the outer surface of the guide piston is a cylindrical surface, a plurality of circumferential oil grooves, a first axial oil groove and a vertical groove are arranged on the cylindrical surface, the vertical groove is formed in the circumferential oil grooves, and the vertical groove is communicated with the circumferential oil grooves through the first axial oil groove; the cylindrical surface is also provided with an inclined hole, and two ends of the inclined hole are respectively communicated with the circumferential oil groove and the inner wall of the second mounting hole; the cylindrical surface is also provided with a second axial oil groove communicated with the circumferential oil groove; the cylindrical surface is also provided with a first straight hole and a second straight hole which are connected, the first straight hole is communicated with the first axial oil groove, and the second straight hole is communicated with the first mounting hole; and a lubricating oil inlet channel is arranged on the outer circular surface of the roller pin and is arranged opposite to the inclined hole, and the lubricating oil inlet channel is communicated with the lubricating oil outlet channel.

Preferably, the outer circle surface of the roller pin is provided with a DLC coating; the roller bushing is made of copper alloy; the thrust bearing is made of copper alloy; forced lubrication is adopted between the roller pin and the roller bushing; and forced lubrication is adopted between the thrust bearing and the lug boss.

Preferably, the common rail pipe is provided with an oil inlet pipeline and an oil return pipeline which penetrate through two ends; an oil inlet end cover is fixed at one end of the common rail pipe, and an oil inlet communicated with the oil inlet pipeline is formed in the oil inlet end cover; an end cover is fixed at the other end of the common rail pipe, an oil outlet communicated with the oil inlet pipeline is formed in the end cover, and the circulating valve assembly is fixed on the end cover; the pressure limiting valve assembly and the plurality of flow limiting valve assemblies are respectively communicated with the oil inlet pipeline, and the pressure limiting valve assembly and the plurality of flow limiting valve assemblies are respectively communicated with the oil return pipeline.

Preferably, the circulation valve assembly comprises: the lower end face of the first valve body is provided with a first middle hole communicated with the oil outlet, the upper end face of the first valve body is provided with a second middle hole, and the first middle hole is communicated with the second middle hole; a first valve body having a first center hole and a second center hole, the first valve body having a lower end surface and a lower end surface; the lower spring seat is sleeved on the part of the first valve core, which is positioned in the second central hole, and is fixedly connected with the first valve core; a first cavity is formed between the lower spring seat and the bottom of the second middle hole; the gland is fixed on the upper end face of the first valve body, and a threaded hole is formed in the upper end face of the gland; the oil return joint is partially fixed in the threaded hole; a first pressure regulating spring that is retained between the lower spring seat and the gland; the first valve body is provided with a first oil return passage communicated with the first middle hole, the press cover is provided with a second oil return passage communicated with the first oil return passage, the oil return joint is provided with a third oil return passage communicated with the second oil return passage, and the first oil return passage, the second oil return passage and the third oil return passage form a circulating oil passage; a first air inlet channel communicated with the first cavity is arranged on the first valve body, and a second air inlet channel communicated with the first air inlet channel and an air inlet communicated with the second air inlet channel are arranged on the press cover; the spring force of the first pressure regulating spring is smaller than or equal to the sum of the pressure of gas pressure introduced into the first cavity and the pressure of oil inlet pressure at the oil inlet end of the first middle hole, the first valve core and the first middle hole form conical surface sealing, and the position where the conical surface sealing is formed is located below the connecting position of the first oil return passage and the first middle hole.

Preferably, a first sealing conical surface and an external thread are arranged on the top of the part, located in the second central hole, of the first valve core, and the external thread is located at the upper end of the first sealing conical surface; the lower spring seat penetrates through the external thread and then is sleeved on the first sealing conical surface, and the lower spring seat is provided with a second sealing conical surface which forms conical surface sealing with the first sealing conical surface; the lower spring seat is compressed through a nut sleeved on the periphery of the external thread; the first pressure regulating spring is sleeved on the nut and fixed on the lower spring seat.

Preferably, the oil return joint is fixed in the threaded hole in a threaded manner; a first sealing plane is arranged at the opening of the threaded hole on the upper end surface of the gland; and a second sealing plane which forms plane sealing with the first sealing plane is arranged on the oil return joint.

Preferably, a third cavity is formed between the lower end face of the oil return joint and the bottom of the threaded hole, the third cavity is communicated with the second oil return channel and the third oil return channel respectively, and the maximum flow area of the third cavity is larger than that of the second oil return channel.

Preferably, when the first valve spool moves upward in the first valve body to a top dead center position, a distance H2 between the first valve body and a lower end surface of the first valve spool is smaller than a distance H1 between a lower end surface of the lower spring seat and a bottom hole of the second center hole.

Preferably, the lower spring seat includes: the third middle hole is used for limiting the first pressure regulating spring, the fourth middle hole is used for being matched with the first valve core, and the aperture of the fourth middle hole is larger than the diameter of the external thread; the outer diameter of the lower spring seat is the same as the pore diameter of the second mesopore.

Preferably, the flow restriction valve assembly comprises: the high-pressure common rail valve comprises a valve seat, a second valve body, a second valve core and a second pressure regulating spring, wherein the valve seat is connected with the high-pressure common rail and is provided with a first oil inlet hole communicated with the high-pressure common rail;

the second valve body has a second axial through hole penetrating through both upper and lower end faces thereof, and the valve seat is press-fitted into the second axial through hole from a lower end face portion of the second valve body; the second valve core is arranged in the second axial through hole and is arranged above the valve seat; the second valve core is provided with an axial blind hole communicated with the first oil inlet, and a cavity is formed between the upper end of the second valve core and the second axial through hole; a transverse throttling hole communicated with the axial blind hole and the cavity is formed in the second valve core; the second pressure regulating spring is sleeved on the second valve core and limited in the cavity; the head at the upper end of the second valve core is provided with a third sealing conical surface and a fourth sealing conical surface which are connected; and a first sealing seat surface capable of forming conical surface sealing with the third sealing conical surface is formed on the hole wall of the second axial through hole, and a gap can be formed between the first sealing seat surface and the fourth sealing conical surface.

Preferably, the second axial through hole comprises a first hole, a second hole, a third hole, a fourth hole, a fifth hole and a sixth hole which are sequentially connected from top to bottom; the valve seat portion is press-fitted into the first bore; the second valve core is assembled in the second hole, and a cavity is formed between the upper part of the second valve core and the upper part of the second hole; the bore wall of the third bore forms the first seal seat face; a second sealing seat surface used for forming sealing with the oil inlet end of the oil pipe of the oil injector is formed on the hole wall of the fifth hole; the sixth hole has a larger hole diameter than the first, second, third, fourth, and fifth holes.

Preferably, a fourth oil return channel is further arranged on the second valve body, one end of the fourth oil return channel is communicated with the sixth hole, and the other end of the fourth oil return channel is communicated with the lower end face of the second valve body; the maximum cross-sectional flow area of the fourth oil return passage is smaller than the maximum cross-sectional flow area of a gap formed between the fourth sealing conical surface and the first sealing seat surface; the maximum cross-sectional flow area of the fourth oil return passage is smaller than the maximum cross-sectional flow area of the second axial through hole and the maximum cross-sectional flow area of the fourth hole.

Preferably, the head part of the lower end of the valve seat is provided with a fifth sealing conical surface for forming conical surface sealing with the high-pressure common rail; the large excircle at the lower end of the valve seat is milled with a first flat, and the first flat is communicated with the fourth oil return channel.

Preferably, the pressure limiting valve assembly comprises: the third valve body is internally provided with a first-stage hole, a second-stage hole, a third-stage hole and a fourth-stage hole which are sequentially communicated from bottom to top; the head part of the third valve core is slidably inserted into the second-stage hole from the fourth-stage hole after passing through the third-stage hole, and the third valve core can form a conical surface seal with the second-stage hole; a first gap for fuel to pass through is formed between the third valve core and the third stage hole, and a second gap for fuel to pass through is formed between the third valve core and the fourth stage hole; the oil pipe joint is fixed the upper end of third valve body, from supreme first counter bore, the second counter bore and the oil outlet that communicate in proper order of being provided with down in the oil pipe joint, the third pressure regulating spring is spacing the third case with between the second counter bore.

Preferably, the pore diameter of the first-stage pore is larger than that of the second-stage pore, and the pore diameter of the third-stage pore is larger than that of the second-stage pore and the fourth-stage pore.

Preferably, the head of the third valve core is provided with a first taper angle and a second taper angle which are connected in sequence, wherein the angle of the first taper angle is 120 degrees, and the angle of the second taper angle is 60 degrees; the excircle in the middle of the third valve element is milled with symmetrically arranged second flat, a second gap for fuel to pass through is formed between the second flat and the hole wall of the fourth-stage hole of the third valve element, and the maximum fuel area capable of flowing in the gap is larger than the maximum fuel area capable of flowing in the second-stage hole; a plurality of grooves are formed in the outer circle of the middle upper part of the third valve element at intervals, and a third gap for fuel oil to pass through is formed between each groove and the corresponding first counter bore; and the third pressure regulating spring is sleeved on the second small excircle on the upper part of the third valve element.

Preferably, a sealing seat surface for forming a conical surface seal with the second taper angle is formed at a connecting part of the second-stage hole and the third-stage hole, and an angle deviation between the sealing seat surface and the second taper angle is smaller than 1 °; the fourth stage hole of the third valve body has the aperture of

Preferably, a travel limit h1 for the third valve core to move is arranged between the third valve core and the hole bottom of the first counter bore of the oil pipe joint; an overlap area h is arranged between the third valve core and the third valve body.

The invention has the beneficial effects that: in the common rail system, multiple valves such as a circulating valve assembly, a pressure limiting valve assembly, a cut-off valve assembly, a safety valve assembly and the like are involved, and each type of valve is started under a specific working condition to realize multiple security of the common rail system.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention; FIG. 2 is a schematic structural diagram of an electrically controlled high pressure oil pump according to the present invention; FIG. 3 is a schematic structural view of an oil inlet and outlet valve assembly; FIG. 4 is a schematic structural diagram of a prior art plunger and barrel assembly; FIG. 5 is a schematic diagram of the cooperation between the plunger and barrel assembly and the pump body and between the oil inlet valve seat and the upper spring seat; FIG. 6 is a schematic view of the structure of the plunger with uneven included angle with the upper ball; FIG. 7 is a schematic view of the engagement between the plunger and the upper sphere after adjustment; FIG. 8 is a schematic view of the lower spring seat assembly and the plunger assembly in mating configuration; FIG. 9 is a cross-sectional view of the lower spring seat assembly; FIG. 10 is a cross-sectional view of the lower spring seat assembly; FIG. 11 is a schematic structural view of an inner spring seat; FIG. 12 is a schematic structural view of an upper sphere; FIG. 13 is a cross-sectional schematic view of the outer spring seat; FIG. 14 is a cross-sectional schematic view of an outer spring seat; FIG. 15 is a cross-sectional schematic view of a pilot piston assembly; FIG. 16 is a schematic cross-sectional view of a pilot piston; FIG. 17 is a schematic view of a pilot piston; FIG. 18 is a schematic cross-sectional view of a pilot piston; FIG. 19 is a schematic view of the roller pin construction; FIG. 20 is an axial cross-sectional view of the roll pin; FIG. 21 is a schematic radial cross-section of a roll pin; FIG. 22 is a schematic view showing the distribution of the stress of the roller assembly without the ring groove; FIG. 23 is a schematic view of the force distribution of the roller assembly with the ring grooves; FIG. 24 is a schematic view of the common rail of the present invention; FIG. 25 is a schematic view of the common rail of the present invention; FIG. 26 is a schematic view of the common rail of the present invention; FIG. 27 is a schematic view of a constrictor valve of the present invention; FIG. 28 is a schematic view of a constrictor valve of the present invention; FIG. 29 is a schematic view of a constrictor valve of the present invention; FIG. 30 is a schematic view of the pressure limiting valve of the present invention; FIG. 31 is a schematic view of the pressure limiting valve of the present invention; FIG. 32 is a schematic structural view of a circulation valve of the present invention; FIG. 33 is a schematic structural view of a circulation valve of the present invention; FIG. 34 is a schematic view of a pilot piston;

description of reference numerals: 1-an electric control high-pressure oil pump; 101-a pump body; 1012-lubricating oil gallery; 102-pump cover: 103-oil inlet and outlet valve assembly; 1031-oil inlet valve assembly; 10311-oil inlet valve seat; 10312-oil inlet valve; 10313-oil inlet valve spring; 1032-an oil outlet valve assembly; 10321-outlet valve seat; 10322-outlet valve; 10323-outlet valve spring; 10324-outlet valve spring seat; 1033-high pressure oil outlet cavity; 104-plunger and barrel assembly; 1041-high pressure oil chamber; 1042-plunger sleeve; 10421 — first ring groove; 10422 — second ring groove; 10423-mixture oil; 10424 — lubricating oil duct; 1043 — plunger; 10431 — lower cylinder head; 105-a plunger spring; 1051 — a first plunger spring; 1052-second plunger spring; 106-lower spring seat assembly; 1061-outer spring seat; 10611-a third counterbore; 10612 — spherical hole; 10613-third ring groove; 10614-lubricant oil inlet pipe: 10615-lubricant oil outlet duct; 10616-locating pin holes; 1062-upper sphere; 10621-circumferential ring groove: 1063-inner spring seat; 10631-first axial through hole; 10632-seventh hole; 10633 — eighth hole; 10634-ninth hole; 10635 — a first pilot hole; 10636 — second pilot hole; 10637-guiding taper; 10638-escape groove; 10639-weight reduction ring groove; 1064-positioning pin; 107-a pilot piston assembly; 1071 — a pilot piston; 10711 — first mounting hole; 10726 — second chamfer; 10712 — second mounting hole; 10713-communicating pores; 10714 — boss; 10715 — first radial oil groove; 10727-tenth hole; 10713 — communicating hole; 10729, 10725 — circumferential oil grooves; 10716 — first axial oil sump; 10717 — vertical trough; 10718 — oblique holes; 10719-second axial oil groove; 10720 — first straight hole; 10721 — second straight hole; 10741 — first chamfer; 1072 — roller assembly; 10728 — roller; 10724 — ring groove; 10722 — roller bushing; 10723 — thrust bearing; 1073 — roller pin; 10731, 10732-kidney slot; 10733, 10734 oil holes; 10735 — oil inlet channel of lubricating oil; 10739 — third radial gallery; 10740-axial oil gallery; 10736 — eleventh hole; 10737-spring; 10738 — stop pin; 2-an electrically controlled proportional valve; 109-upper spring seat; 3-a first high pressure oil pipe; 5-a shut-off valve assembly; 6 — first allocation block; 7-a safety valve assembly; 8-a second high pressure oil pipe; 9 — second allocation block; 10-a third high pressure oil pipe; 14-a fourth high pressure fuel line; 15-electric control oil injector; 12-common rail pipe; 1201-oil inlet pipe; 1202-oil return line; 1203-first incision; 1204-second cut; 121-an oil inlet end cover; 122-end cap; 123-a pressure limiting valve mounting seat; 124-a sensor; 125-a flow-limiting valve mount; 126-a support; 127-a sensor mount; 128-bolt; 129-screw; 16-a circulation valve assembly; 161-a first valve body; 1601 — first mesopore; 1602 — second mesopores; 1605-first oil return; 163-third seal ring groove; 1602 — second mesopores; 1619-a guide; 1620 — first seal ring groove; 1622-second seal ring groove; 1608 — first intake; 1623-air outlet channel; 162 — a first valve spool; 1611 — a first sealing cone; 1612-external thread; 1624-third sealing ring; 164-a lower spring seat; 1617 — third mesopore; 1618 — fourth mesopore; 1613 — a second sealing cone; 1625-fourth seal ring groove; 1626-a mating portion; 1627-fourth sealing ring; 1628-first sealing ring; 167-pressing cover; 1606 — second oil return; 1603-threaded hole; 1629 — second inlet; 1630 — an air inlet; 1615 — a first sealing plane; 168-oil return joint; 1616 — second sealing plane; 1607-third oil return; 169-first pressure regulating spring; 1614-a nut; 1631 — a second seal ring; 1632 — screw; 18-a pressure limiting valve assembly; 181 — a third valve body; 182 — a third spool; 183-second O-ring; 184-bolt; 185-third pressure regulating spring; 186-tubing joint; 187-a pressure regulating gasket; 18101 — first stage aperture; 18102 — second stage aperture; 18103 — sealing seat surface; 18104-third level hole; 18105-fourth stage hole; 18601 — first counterbore; 18602 — second counterbore; 18603 — oil outlet; 18201 — first taper angle; 18202 — second taper angle; 18203 — second flat; 18204 — third outer circle; 18205-a groove; 18206 — second small outer circle; h-overlap region; h 1-range limit; 13-a restrictor valve assembly; 131-valve seat; 132 — a second valve body; 133 — a second spool; 136 — a first O-ring; 135-second pressure regulating spring; 13101 — a first oil inlet; 13102 — fifth sealing cone; 13103-sink tank; 13104-first flat; 13105-large end face; 13106 — first small outer circle; 13201 — small end face; 13202-large bevel; 13203 — a first mating portion; 13204 — a second mating portion; 13205 — a third bore; 13206 — a first seal seat surface; 13207 — a fourth well; 13208 — a second seal seat surface; 13209 — a second axial through hole; 13210 — fourth oil return; 13211 — screw mounting holes; 13301 — first outer circle; 13302-axial blind hole; 13303 — second outer circle; 13304 — transverse orifices; 13305-a third sealing cone; 13306-fourth sealing cone.

Detailed Description

Referring to fig. 1, the present invention provides a low speed engine high pressure common rail system with multiple security functions, comprising: the device comprises an ECU (electronic control unit), an electronic control high-pressure oil pump 1, and an electronic control proportional valve 2 arranged in the electronic control high-pressure oil pump, wherein the electronic control proportional valve 2 is used for carrying out oil inlet proportion adjustment on low-pressure heavy oil entering the electronic control high-pressure oil pump 1 from an oil tank of a low-speed machine according to a first instruction of the ECU; the electric control high-pressure oil pump 1 adopts a single-plunger structure, and the system is provided with three electric control high-pressure oil pumps 1 as a backup to prevent the failure of the system caused by the failure of the high-pressure oil pumps. The first distribution block 6 is connected with the electric control high-pressure oil pump 1 through a first high-pressure oil pipe 3; a second distribution block 9 connected to the first distribution block 6 through a second high-pressure oil pipe 8; a common rail pipe 12 connected to the second distribution block 9 through a third high pressure oil pipe 10; a sensor 17 for detecting the fuel pressure of the high-pressure heavy oil of the common rail pipe 12 is arranged on the common rail pipe 12, and the sensor 17 is connected with the ECU; a plurality of flow limiting valve assemblies 13 are mounted on the common rail pipe 12, and each flow limiting valve assembly 13 is connected with one electric control oil injector 15 through a fourth high-pressure oil pipe 14; the restrictor valve assembly 13 is adapted to close when the difference in fuel pressure between the fourth high pressure conduit 14 and the common rail conduit 12 exceeds a set pressure differential value; a restrictor valve assembly 13 is mounted on the common rail 12 and its outlet is connected to an electrically controlled fuel injector 15 by a fourth high pressure fuel line 14. And a plurality of oil injectors are arranged in each cylinder, and each oil injector is provided with an independent flow limiting valve assembly 13. When the fourth high-pressure oil pipe 14 is broken or the electric control oil injector 15 abnormally injects, the flow limiting valve assembly 13 cuts off the high-pressure fuel oil to be led into the electric control oil injector 15, and the safety of the low-speed engine is protected. The fourth high-pressure oil pipe 14 is designed to be double-walled, and low-pressure abnormal leakage of all double-layered fourth high-pressure oil pipes 14 is communicated with low-pressure abnormal leakage of connected components, so that a system low-pressure abnormal leakage oil return system is formed.

The common rail pipe 12 is also provided with a pressure limiting valve assembly 18, and the pressure limiting valve assembly 18 is used for opening when the fuel pressure in the common rail pipe 12 exceeds a first set pressure value, so that the fuel pressure in the common rail pipe 12 is stabilized to a target pressure value; the pressure limiting valve assembly 18 is installed on the common rail pipe 12, and the pressure limiting valve assembly 18 is of a mechanical structure and has the capacity of maintaining the working of fault pressure after constant pressure opening. When the system pressure exceeds 125MPa, the pressure limiting valve assembly 18 automatically opens and enters a failure mode, keeping the system operating safely at the pressure required by the failure mode.

The first distribution block 6 is provided with a cut-off valve assembly 5 and a safety valve assembly 7; the shut-off valve assembly 5 is used for carrying out pressure relief treatment according to a second instruction of the ECU; the safety valve assembly 7 is used for opening when the stop valve assembly 5 and the pressure limiting valve assembly 18 fail and the fuel pressure in the common rail pipe 12 exceeds a second set pressure value; the stop valve assembly 5 is of a pneumatic control structure and is installed on the first distribution block 6, so that the system pressure can be discharged quickly. When the low-speed engine or the fuel system has an emergency and needs emergency stop, the cut-off valve assembly 5 is quickly opened as a second pressure protection measure to quickly release the system pressure. The cut-off valve assembly 5 adopts an independent oil return system and is separated from a system static abnormal leakage oil return system. The safety valve component 7 is of a mechanical structure and is arranged on the first distribution block 6, and the opening pressure of the safety valve component is 150 MPa. When the system is out of control and the shutoff valve assembly 5 and the pressure limiting valve assembly 28 are also failed, the safety valve assembly 7 is opened as a second protection, so that the safety of the whole system is ensured.

And the common rail pipe 12 and the electronic control fuel injector 15 are also provided with a circulating valve assembly 16, and the circulating valve assembly 16 is used for opening when the low-speed engine stops so as to form a circulating loop between the common rail pipe 12 and the electronic control fuel injector 15 and a fuel tank of the low-speed engine respectively. The circulation valve assembly 16 is mounted on the end cover 122 and each of the electronically controlled fuel injectors 15, respectively. When the engine is started, the common rail pipe 12 and the electronic control fuel injector 15 have no fuel, at the moment, a valve core in the circulating valve assembly is at a bottom dead center position, the circulating valve assembly 16 is in an opening circulating state, compressed air is introduced into the circulating valve assembly 16 to enable the circulating valve assembly 16 to quickly close the system to start pressure building in order to enable the common rail system to quickly build pressure to work, and when the pressure exceeds the pre-tightening force of a spring of the circulating valve assembly 16, the closing of the circulating valve mainly depends on the pressure of the fuel; when the system is shut down, the pressure of the system is reduced by the cut-off valve assembly 5, and the circulating valve assembly 16 is automatically opened, so that the low-pressure automatic circulating function is realized, and the safety of heavy oil of the system is ensured. After the diesel engine is shut down and pressure is released, the circulating valve assembly 16 is opened, so that heavy oil in the system is cooled and solidified, parts are corroded, and the service life of the parts is shortened; at the moment, the system enters a low-pressure circulation mode, low-pressure fuel oil enters the common rail pipe 12 after passing through the high-pressure oil pipe, and the post-pressure fuel oil is divided into two branches. One from the circulation valve assembly 16 mounted on the oil inlet end cap 121 to the oil tank; the other enters the electronic control fuel injector 15 through the flow limiting valve assembly 16, and flows out to the fuel tank through the circulating valve assembly 16 arranged on the electronic control fuel injector 15. The circulation valve assembly 16 on the oil inlet end cover 121 must be provided with a smaller flow area than the circulation valve assembly 16 on the electronically controlled fuel injector 15. If the flow area of the circulating valve assembly 16 is not well matched with the flow area of the electronic control fuel injector 15, low-pressure fuel will flow out of the circulating valve assembly 16 at the oil inlet end cover 121, no fuel flows out of the circulating valve assembly 16 of the electronic control fuel injector 15, and the fuel circulation at the position cannot be realized. It is important that the flow areas of the two circulation valve assemblies 16 match in size, and the flow area of the circulation valve assembly 16 is determined by the lift of the spool.

In the whole common rail system static seal abnormal leakage oil return system, an electric control oil injector 15, a fourth high-pressure oil pipe 14, a flow limiting valve assembly 13, a common rail pipe 12, an oil inlet end cover 121, a third high-pressure oil pipe 10, a second distribution block 9, a second high-pressure oil pipe 8, a first distribution block 6, a first high-pressure oil pipe 3 and an electric control high-pressure oil pump 1 are communicated, and oil is returned after the lowest electric control high-pressure oil pump 1 leaks.

This automatically controlled high-pressure oil pump 1 is marine monomer formula high-pressure oil pump, and this oil pump specifically includes: pump body 101, pump body 101 is equipped with the mesopore along the axial direction. The pump cover 102 is attached to the upper end surface of the pump body 101. The oil inlet and outlet valve assembly 103, the plunger matching part 104, the plunger spring 105, the lower spring seat assembly 106 and the guide piston assembly 107 are assembled in a central hole of the pump body 101. And an electrically controlled proportional valve 2 mounted on the side of the pump body 101. The oil inlet and outlet valve assembly 103 includes: an inlet valve assembly 1031 and an outlet valve assembly 1032. The oil feed valve assembly 1031 includes: an oil inlet valve seat 10311, an oil inlet valve 10312 and an oil inlet valve spring 10313. An oil inlet valve 10312 is installed in a central hole of the oil inlet valve seat 10311; the oil inlet valve spring 10313 is limited between the oil inlet valve 10312 and the hole wall of the oil inlet valve seat 10311; under the compression of the oil inlet valve spring 10313, the oil inlet valve 10312 forms a conical surface seal with the oil inlet valve seat 10311. The delivery valve assembly 1032 includes: an oil outlet valve seat 10321, an oil outlet valve 10322, an oil outlet valve spring 10323, and an oil outlet valve spring seat 10324. An oil outlet valve spring seat 10324 is installed at an upper end of the oil outlet valve seat 10321; the oil outlet valve 10322 is installed in a central hole of the oil outlet valve seat 10321; the oil outlet valve spring 10323 is restrained between the oil outlet valve 10322 and the oil outlet valve spring seat 10324; the oil outlet valve 10322 forms a tapered seal with the oil outlet valve seat 10321 under the compression of the oil outlet valve spring 10323. A high-pressure oil outlet chamber 1033 is formed between the oil outlet valve seat 10321 and the oil inlet valve seat 10311. A high-pressure oil chamber 1041 is formed in the plunger and barrel assembly 104, and the high-pressure oil chamber 1041 is communicated with the high-pressure oil outlet chamber 1033 through an oil hole in the oil inlet valve seat 10311. The electric control proportional valve 2 is communicated with an oil inlet hole of the oil inlet valve seat 10311 through an oil hole on the pump body 101, and the oil inlet hole is communicated with or disconnected from the high-pressure oil chamber 1041. The electrically controlled proportional valve 2 is provided with a cooling circulation oil passage, and cooling oil from the cooling oil passage of the pump body 101 flows back to the cooling oil passage of the pump body 101 after being injected into the cooling circulation oil passage.

As shown in fig. 2, the central hole provided in the pump body 101 is a through hole penetrating both upper and lower end surfaces of the pump body 101. The pump cover 102 is fixed to the upper end surface of the pump body 101, and a mounting hole facing the center hole of the pump body 101 is provided in the direction in which the pump cover 102 faces the main body 1, and the outlet valve seat 10321 is mounted in the center hole of the pump body 101 and the mounting hole of the pump body 101. As can be seen from fig. 2, the oil outlet valve assembly 1032 is installed above the oil inlet valve assembly 1031, and an oil passage communicating with the oil outlet valve assembly 1032 is provided above the pump cover 102, and finally, the high-pressure heavy oil pumped out by the high-pressure oil pump of the present application is discharged through the oil passage on the pump cover 102.

The electric control proportional valve 2 is used as a hydraulic control device, and has an oil inlet throttling effect, the electric control proportional valve 2 is mainly used for oil inlet regulation and control of light oil (such as gasoline, diesel oil) and the like, and in the prior art, a scheme for applying the electric control proportional valve 2 to oil inlet regulation and control of heavy oil does not exist, because the temperature of the heavy oil can reach 160 ℃ when the heavy oil works, and the temperature exceeds the limit working temperature of electric control elements such as an armature, a coil and the like of the existing electric control proportional valve 2. In the prior art, the oil inlet throttling regulation of a high-pressure oil pump using heavy oil is in a mechanical transmission design, namely, the oil quantity is controlled through a speed regulator and a spiral groove above a plunger piston, and the oil inlet regulation mode has the defects of low oil quantity regulation precision, low correspondence speed, dependence of the oil quantity on the rotating speed of the speed regulator and the like.

In the embodiment of the application, use automatically controlled proportional valve 2 to come to carry out the oil feed to adjust to the heavy oil, can solve the not strong and high temperature problem of current mechanical regulation mode flexibility. Specifically, a cooling circulation oil passage is provided inside the electrically controlled proportional valve 2, so that the cooling oil flowing in the pump body 101 enters the electrically controlled proportional valve 2, and the electrically controlled elements in the electrically controlled proportional valve 2 are cooled specifically, so that the electrically controlled elements of the electrically controlled proportional valve 2 are kept within a normal temperature range. The cooling circulation oil passage designed in the electrically controlled proportional valve 2 should satisfy the following requirements: (1) the electric control elements such as a coil and an armature close to the electric control proportional valve as much as possible; (2) the flow of the cooling oil introduced into the cooling circulation oil passage can reduce the temperature of electric control elements such as a coil, an armature and the like to be within a working temperature range. In order to enable the cooling circulation oil passage to meet the requirements, simulation calculation and experiments are required to be performed in advance for armatures of different models, and specific parameter information such as spatial arrangement and size of the cooling circulation oil passage in each model is determined. The design has the advantages that the cooling circulation oil passage is arranged in the electric control proportional valve 2, so that the temperature of the armature and the coil of the electric control proportional valve 2 is reduced, the electric control element works in a normal temperature range, and the electric control proportional valve 2 is allowed to be used for oil inlet throttling of the pump. The electric control proportional valve 2 overcomes the defect of mechanical oil quantity regulation, improves the precision, flexibility and response speed of oil supply flow regulation, further realizes more accurate matching of the oil supply quantity of the pump and the operation condition of the diesel engine, avoids performance reduction caused by insufficient oil supply, also reduces surplus flow during working, and further reduces the actual load of the pump.

As shown in fig. 3, in the oil filling stage, the oil inlet valve 10312 is opened under the action of the oil inlet pressure of the electrically controlled proportional valve 2, the oil outlet valve 10322 is sealed with the oil outlet valve seat 10321 under the action of back pressure, the low-pressure heavy oil enters the electrically controlled proportional valve 2 from the oil inlet into the high-pressure oil cavity 1041 to start oil filling, and the oil inlet amount is controlled by adjusting the opening degree of the electrically controlled proportional valve 2 to meet different working condition requirements; in the oil pumping stage: the guide piston assembly 107 moves upward, the plunger 1043 compresses heavy oil in the high-pressure oil chamber 1041, the pressure of the heavy oil gradually rises, when the pressure of fuel oil in the high-pressure oil chamber 1041 is greater than the pressure of fuel oil, the fuel inlet valve 10312 is closed, because the high-pressure fuel outlet chamber 1033 is connected with the high-pressure oil chamber 1041, when the pressure of the fuel oil in the high-pressure oil chamber 1041 exceeds the back pressure and the spring force of the fuel outlet valve, the fuel outlet valve 10322 is opened, and the high-pressure fuel oil is discharged from the middle hole of the pump cover 102 through the. As shown in fig. 4, the previous high-pressure common rail heavy oil pump is of a mechanical design, and an oil inlet pipe 505 is provided on a plunger barrel 6, and a plunger 5 is slidably inserted in the plunger barrel 6, and an oil inlet valve assembly is not provided. In operation, when oil suction and compression are alternated, a portion of pressurized fuel will flow back from the fuel inlet pipe 505 to the low pressure fuel inlet passage, which in turn causes a large pressure change in the fuel inlet pipe 505, thereby causing the location associated with the fuel inlet pipe 505 to be susceptible to cavitation. This is also one of the main failure modes of the plunger and barrel assembly in the actual ship experiment. Compared with the prior art, the oil inlet valve assembly 1031 is additionally arranged, the high-pressure oil cavity of the plunger sleeve 1042 is quickly closed when the high-pressure oil cavity is converted from oil absorption to compression, the pressure stability of the relevant position in the oil inlet channel of the oil inlet valve seat 10311 is guaranteed, and cavitation erosion is effectively prevented.

Referring to fig. 5, the plunger and barrel assembly 104 includes: and a plunger sleeve 1042 disposed at a lower end of oil inlet valve seat 10311. And a plunger 1043 slidably inserted into the central hole of the plunger sleeve 1042, wherein a high-pressure oil chamber 1041 is formed among the plunger sleeve 1042, the plunger 1043 and the oil inlet valve seat 10311. The inner wall of the plunger sleeve 1042 is provided with a first ring groove 10421 and a second ring groove 10422. The pump body 101 is provided with a mixed oil outlet channel and a lubricating oil channel 1012, the mixed oil outlet channel is communicated with the first annular groove 10421 through a mixed oil channel 10423 on the plunger sleeve 1042, the mixed oil formed at the first annular groove 422 flows out to the waste oil tank through the mixed oil outlet channel and a mixed oil channel 10423, and the lubricating oil channel 1012 is communicated with the second annular groove 10422 through a lubricating oil channel 10424 on the plunger sleeve 1042. The first ring groove 10421 is located above the second ring groove 10422. The lubricating oil entering the second annular groove 10422 has 2 functions: 1. the fuel entering a gap between the plunger 1043 and the plunger sleeve 1042 from the high-pressure oil cavity 1041 above the plunger 1043 has a sealing effect, so that the fuel can be prevented from flowing into a transmission part below the plunger 1043, and the fuel is prevented from invading into the transmission part below the plunger 1043 to pollute a whole machine lubricating oil system; 2. the friction surfaces below the plunger 1043 are all in a clean oil lubrication state, and the friction state of the plunger 1043 is improved. Compared with the above heavy oil, the lubricating oil has high cleanliness, contains an additive for improving friction in the lubricating oil, and can form a better oil film compared with the lubricating oil lubricated by the heavy oil.

Since the conventional low speed machine allows the heavy oil to leak under the plunger 1043, the leaked heavy oil is separately collected. But the leaked heavy oil risks corroding the plunger spring 105 and other components below the plunger 1043. In this application, the leakage of heavy oil can be completely prevented by using a small amount of lubricating oil in the second annular groove 10422 of the plunger matching part 104, and the leaked heavy oil can be prevented from corroding important parts such as the plunger spring 105 below the plunger sleeve 1042. In addition, because be equipped with complicated dynamic seal mechanism on the guide piston of traditional low-speed engine plunger below, lead to the whole vertical height of high-pressure oil pump great, characteristics such as cost height, this application is through the heavy oil of a small amount of lubricating oil seal, the vertical height of guide piston 1071 that can effectively reduce (be equipped with longer heavy oil seal section on the traditional heavy oil guide piston), and then reduce the pump vertical height of high-pressure oil pump, alleviate the gross weight of high-pressure oil pump, learn according to the experiment, the scheme of this application, 1/3 has been reduced with the vertical height of high-pressure oil pump.

Referring to fig. 7 to 14, a lower spring seat assembly 106 is disposed below the plunger and barrel assembly 104, the lower spring seat assembly 106 including: the outer spring seat 1061 is of a boss type structure with a thin outer side and a thick middle part, and in operation, the outer spring seat 1061 mainly bears the pressure transmitted by the plunger 1043 to the upper ball, and the stress field caused by the pressure is distributed in the outer spring seat 1061 in a tapered manner. The outer spring seat 1061 is in a boss shape corresponding to the outer spring seat, so that the mass of the outer spring seat 1061 can be reduced under the condition of meeting the strength, the moving mass is further reduced, and a design space is provided for the middle spherical surface and the oil passage by the thick part between the bosses.

The upper end surface of the outer spring seat 1061 is provided with a third counter bore 10611 in a concave spherical surface; and the lower part of the upper sphere 1062 is installed in the third counter bore 10611, and the lower end surface of the upper sphere 1062 is provided with a convex spherical surface matched with the concave spherical surface. The inner spring base 1063 is disposed on the upper portion of the upper ball 1062, and the inner spring base 1063 has a first axial through hole 10631 penetrating the upper and lower end surfaces.

The lower cylindrical head 431 of the plunger 1043 is limited in the first axial through hole 10631, and the lower end surface of the lower cylindrical head 431 of the plunger 1043 abuts against the upper end surface of the upper sphere 1062. According to experiments, when the plunger works, because a parallelism error exists between the tail plane and a corresponding pressing surface (a guide piston or a spring seat surface), local overlarge stress on the tail plane of the plunger 1043 (in fig. 6, an included angle with an angle beta is formed between the upper ball 1062 and the plunger 1043) may be caused during pressing, and due to uneven stress distribution, additional moment about the central plane of the plunger 1043 is generated, so that additional load and energy loss are brought to a system, and the dynamic characteristics of the system are influenced. When the lower spring seat assembly 106 with the spherical surface is arranged between the plunger 1043 and the guide piston 1071, even if the upper end surface of the guide piston 1071 and the end surface of the tail part of the plunger 1043 have large parallelism errors, the spherical surface can be automatically adjusted in angle, so that the contact surface between the upper ball 1062 and the outer spring seat 1061 is kept in full contact (the state in fig. 7 is changed from the state in fig. 6, and in fig. 7, the two contact surfaces of the upper ball 1062 and the plunger 1043 are attached), the local contact is eliminated, the overall stress is balanced, and the trend of overlarge local stress is relieved. Meanwhile, the resultant force passes through the center of the spherical surface, so that the bending moment of the accessory is eliminated, the dynamic characteristic is optimized, and the bearing capacity of the system is improved.

Referring to fig. 9 to 14, a spherical hole 10612 is formed in the center of the third counterbore 10611, a third ring groove 10613 is formed in the lower end surface of the outer spring seat 1061, the spherical hole 10612 is communicated with the third ring groove 10613 through a lubricating oil inlet pipe 10614, the lubricating oil inlet pipe 10614 is communicated with an oil passage on the guide piston 7, and lubricating oil forms an oil film on the convex spherical surface of the outer spring seat 1061 through the lubricating oil inlet pipe 10614, so that fretting wear damage between the convex spherical surface of the upper ball 1062 and the concave spherical surface of the outer spring seat 1061 can be effectively prevented; the spherical hole 10612 provides lubricating oil for the spherical surface to lubricate the spherical surface, and the lubricating oil is utilized to form an elastic flow lubricating effect on the spherical surface, so that the wear rate is reduced, the contact stress is reduced, the fretting damage is reduced, and the bearing capacity and the fatigue strength of the spherical surface are improved.

The outer surface of the outer spring seat 1061 forms a conical surface, the conical surface is provided with a lubricating oil outlet channel 10615, and the lubricating oil outlet channel 10615 is communicated with the lower end surface of the outer spring seat 1061; the lubricating oil outlet channel 10615 is obliquely arranged; the main purpose of the lubricant outlet channel 10615 is to communicate the upper and lower areas of the outer spring seat 1061, so that the lubricant above the outer spring seat 1061 smoothly flows into the lower area, and prevent the lubricant chamber above the outer spring seat 1061 from being filled with lubricant and compressing the additional load caused by the lubricant. The lubricating oil outlet channel 10615 is formed in the outer conical surface of the outer spring seat 1061, so that the plunger spring 105 is prevented from covering the flow area of the lubricating oil outlet channel 10615, and the flow area is not affected by the position of the plunger spring 105.

The number of the lubricating oil outlet channels 10615 is specifically 8; the plurality of lubricating oil outlet passages 10615 are respectively communicated to the bottom end surface of the outer spring seat 1061. Lubricating oil in the upper space of the outer spring seat 1061 can be ensured to flow out smoothly, and additional load caused by accumulation of the lubricating oil is avoided; meanwhile, the lubricating oil outlet channel 10615 is obliquely arranged on the conical surface of the outer spring seat 1061, so that the phenomenon that the plunger spring 105 blocks the lubricating oil outlet channel 10615 to cause unsmooth circulation of the lubricating oil and cause accumulation is also prevented. A circumferential groove 10621 is formed in the upper sphere 1062 in the circumferential direction. The dowel pin 1064 is installed in the circumferential groove 10621 after passing through the dowel pin hole 10616 of the outer spring seat 1061. The distance between the upper and lower surfaces of the circumferential groove 10621 is greater than the diameter of the portion of the dowel 1064 located in the circumferential groove 10621. The upper sphere 1062 and the outer spring seat 1061 are connected by a threaded locating pin 1064, the locating pin 1064 is fixed on the outer spring seat 1061 by a thread, the head of the locating pin 1064 is a cylindrical surface, which is a locating portion, and the upper sphere 1062 is provided with a corresponding circumferential groove 10621 for installing the head of the pin. The circumferential groove 10621 of the upper sphere 1062 may also be a circular hole. The dowel 1064 may substantially align the upper ball 1062 and the outer spring seat 1061 to prevent the upper ball 1062 from falling out of the outer spring seat 1061 during reciprocation when the plunger 1043 and the upper ball 1062 are separated.

As shown in fig. 11, the first axial through hole 10631 provided inside the inner spring seat 1063 includes: a seventh hole 10632, an eighth hole 10633, and a ninth hole 10634, which have diameters that gradually increase from top to bottom; a first guide 10635 with a gradually increasing diameter is arranged between the second hole 632 and the ninth hole 10634; the ninth hole 10634 is provided with a second guide hole 10636 having a gradually increasing diameter toward the side of the upper sphere 1062; the hole walls of the first guide hole 10635 and the second guide hole 10636 are formed as guide tapered surfaces 10637; the upper portion of the upper sphere 1062 is partially positioned in the ninth hole 10634 through the second guide hole 10636. Wherein, the upper end surface of the lower cylindrical head 431 of the plunger 1043 is abutted with the upper end surface of the eighth hole 10633; the wall of the eighth hole 10633 is fitted around the lower cylindrical head 10431 of the plunger 1043. Since the hole walls of the first guide hole 10635 and the second guide hole 10636 are formed as the guide tapered surface 10637, if the plunger 1043 and the upper sphere 1062 are separated or the inner spring seat 1063 and the plunger 1043 are separated, when the plunger 1043 hits the upper sphere 1062 again, the guide tapered surface 10637 automatically aligns the plunger 1043 and the upper sphere 1062, the plunger 1043 and the inner spring seat 1063, and the inner spring seat 1063 and the upper sphere 1062, thereby preventing large angular deviation and radial displacement between the plunger 1043 and the inner spring seat 1063, and the upper sphere 1062, and further ensuring that the system is in a proper position even if the system is hit, so that the overall stress is balanced. Specifically, when the plunger 1043 snaps, the inner spring seat 1063 is relatively stationary (i.e., snaps at a top dead center), the outer spring seat 1061 and the upper ball 1062 may reciprocally impact. The inner spring seat 1063 and plunger 1043 may not be centered with the upper sphere 1062 at impact, resulting in localized forces at impact. The inner spring seat 1063 is provided with the guide conical surface 10637, so that the centering performance can be improved, the inner spring seat 1063 and the upper ball 1062 can be automatically aligned even if the ball is impacted, and the uneven stress tendency is improved.

A clearance larger than or equal to 1mm is formed between the upper sphere 1062 and the ninth hole 10634, specifically, a clearance of 1mm is formed between the outer cylindrical surface of the upper sphere 1062 and the hole wall of the ninth hole 10634, and since the outer spring seat 1061 and the upper sphere 1062 are in spherical fit and have a large (millimeter-sized) clearance, the two can slide freely relative to each other, during the operation of the plunger, if an angle error exists between the lower end surface of the lower cylindrical head 431 of the plunger 1043 and the upper end surface of the upper sphere 1062, when the plunger 1043 moves downward and hits the upper sphere 1062, the upper sphere 1062 can slide relative to the outer spring seat 1061 to automatically compensate the angle error, so that the lower end surface of the lower cylindrical head 431 of the plunger and the upper end surface of the guide piston 1071 are stressed uniformly during the additional load, and the local stress can be effectively prevented from being too large.

A gap larger than or equal to 1mm is formed between the third counterbore 10611 and the upper sphere 1062, specifically, a gap of 1mm is formed between the outer cylindrical surface of the upper sphere 1062 and the cylindrical surface of the third counterbore 10611, that is, a gap of larger (1mm) is formed between the upper sphere 1062 and the inner spring seat 1063, and gaps of larger (1mm) are formed between the positioning pin 1064 and the upper sphere 1062, between the positioning pin 62 and the outer spring seat 1061, and between the upper sphere 1062 and the inner spring seat 1063, so that the effective rotational freedom of the upper sphere 1062 in the radial movement is not limited by the positioning pin 1064, and the effective rotational freedom of the plunger 1043 and the upper sphere 1062 in the radial movement is not limited by the inner spring seat 1063, thereby preventing additional radial load of the plunger 1043.

Millimeter-scale gaps are formed between the upper sphere 1062 and the ninth hole 10634 and between the third counter bore 10611 and the upper sphere 1062, so that macroscopic angle errors of the upper sphere 1062 relative to the outer spring seat 1061 are allowed, the spherical surface is prevented from being clamped, and the effects of eliminating local contact, balancing overall stress and relieving the trend of overlarge local stress are achieved. In addition, as shown in fig. 11, relief grooves 10638 are formed on the outer circumferential surface of the inner spring seat 1063 and the hole wall of the second blind hole 6312; the upper end surface of the inner spring seat 1063 is provided with a weight-reduction ring groove 10639 around the center axis.

Referring to fig. 2, further includes: the upper spring seat 109 is sleeved on the plunger sleeve 1042 and is positioned at the upper end of the inner spring seat 9; the plunger spring 105 includes: a first plunger spring 1051 that is press-fitted between the upper spring seat 109 and the outer spring seat 1061; a second plunger spring 1052 press-fitted between the upper spring seat 109 and the inner spring seat 1063. The diameter of the concave spherical surface in the outer spring seat 1061 and the convex spherical surface of the upper sphere 1062 is 20 to 100 times the diameter of the plunger 1043. The parallelism error magnitude of the tail part of the plunger 1043 and the upper end surface of the guide piston 1071 is lower and is generally 0.01 magnitude, the requirement on the adjustment capability of the spherical angle is low, and therefore the small-angle spherical adjustment can also meet the requirement on the angle adjustment. When the spherical surface is large, only a small part of the acting force of the two surfaces is converted into tensile stress when the spherical surface is pressed, and for metal materials, the general compressive strength is higher than the tensile strength, and the compressive stress is not easy to cause fatigue, so that the tensile stress proportion can be reduced by selecting the large spherical surface, and the bearing capacity and the fatigue strength of the material are improved.

Referring to fig. 15 to 21, the pilot piston assembly 107 includes: a guide piston 1071 having a first mounting hole 10711 formed at a central position of an upper end surface thereof; a second mounting hole 10712 is formed in a lower end surface thereof, the first mounting hole 10711 and the second mounting hole 10712 are communicated with each other through a communication hole 10713, and the lower spring seat assembly 106 is mounted in the first mounting hole 10711. The roller assembly 1072, including: a roller 10728 mounted in the second mounting hole 10712, a roller bushing 10722 interference-fitted in the roller 10728, and thrust bearings 10723 interference-fitted at both axial ends of the roller 10728; the roller 10728 is axially provided with a ring groove 10724, and the groove bottom of the ring groove 10724 is in arc transition connection with the axial end face of the roller 10728. Roller pin 1073, which fits with clearance in roller bushing 10722. A boss 10714 is provided to protrude from a hole wall of the second mounting hole 10712, and the boss 10714 contacts the thrust bearing 10723. The boss 10714 is uniformly arranged with a plurality of first radial oil grooves 10715 in the radial direction, the first radial oil grooves 10715 being provided with respect to the thrust bearing 10723.

The roller bushing 10722, the thrust bearing 10723 and the roller 10728 are all in interference fit, so that the moving surface is reduced and the moving speed of the friction surface is increased. In the dynamic pressure lubrication theory, the friction coefficient decreases as the relative movement speed of the friction surface increases within a certain range. Therefore, the relative movement speed is increased, the dynamic pressure lubrication effect is enhanced, a thicker dynamic pressure oil film is formed on the corresponding friction surface, solid contact is avoided, and the friction coefficient and abrasion are reduced.

Due to the communication hole, the following effects are achieved: (1) when the lubricating oil above the guide piston 1071 flows down from the communicating hole 10713, the lubricating oil is uniformly distributed in the middle right above the second mounting hole 10712 of the roller 10728, the lubricating oil is uniformly distributed on the bus of the roller 10728, and the distribution of the lubricating oil on the surface of the roller 10728 is not influenced by positive and negative rotation (can be uniformly distributed); (2) the vertical stress distribution of the guide piston 1071 is improved, namely the pressure of the plunger 1043 is distributed to a thick position around the communicating hole 10713, so that the whole stress is balanced, the maximum stress is reduced, and the reliability of the bearing capacity of the system is improved. (in the traditional guide piston, a communication hole is arranged around the center, and the position of the communication hole is solid, so that the position is thin and the stress is large); (3) in the pump assembly, when the guide piston 1071 is matched with the outer spring seat 1061, the lubricating oil outlet oil channel 10615 of the outer spring seat 1061 is communicated with the lubricating oil leaked above the plunger and barrel assembly 104, so that the oil hole can be prevented from being blocked by the spring, and the actual flow area of the lubricating oil is increased.

This annular 10724 is through reprocessing the formation after finishing gyro wheel 10728 hole and excircle, as fig. 22 and 23, annular 10724's setting has reduced gyro wheel 10728 both ends rigidity, when gyro wheel 10728 surface receives radial pressure, near the gyro wheel 10728 of annular 10724 can automatic deformation at present, and simultaneously, behind the processing annular 10724, gyro wheel 10728 excircle and hole automatic collapse form the microcosmic cambered surface at gyro wheel 10728 hole and excircle both ends, reduce the geometric stress concentration at gyro wheel 10728 both ends, and then make gyro wheel 10728 surface stress balanced. (geometric stress concentration: when the surface of the roller 10728 is stressed, the contact stress at both ends of the generatrix of the roller 10728 is significantly greater than that at the middle). The groove wall of the ring groove 10724 is formed into an arc shape, which can effectively weaken the collective stress concentration existing on the outer cylindrical surface of the roller 10728 and the side pressure effect of the inner hole of the roller 10728 in the rotation process of the roller 10728, so that the stress distribution of the inner working surface and the outer working surface of the roller 1072 is balanced, thereby reducing the probability of seizure between the roller 1072 and the roller pin 1073.

The bosses 10714 form thrust bearing models with corresponding friction surfaces (roller assembly end faces). Namely, the first radial oil groove 10715 is filled with lubricating oil to provide sufficient lubricating oil for the moving surface (the end surface of the roller assembly), and a dynamic pressure oil film is formed on the end surface of the roller 10728 by utilizing the moving speed of the end surface of the roller 10728 to separate the boss 10714 of the guide piston 1071 from the end surface of the roller assembly 1072, thereby reducing abrasion and reducing the friction coefficient. A first radial oil groove 10715 is formed on boss 10714 of guide piston 1071 as compared with that formed on roller assembly 1072. The guide piston 1071 does not rotate relatively, the friction surface area of the high and low pressure oil film is relatively static, and the roller assembly 1072 is axially relatively static. If the first radial oil groove is formed in the moving member (end surface of the roller assembly 1072), the relative movement of the first radial oil groove with respect to the guide piston 1071 may cause the oil film to be distributed and moved relatively, and further cause the roller 10728 to vibrate excessively in the axial direction, thereby reducing the overall dynamic performance.

For roller 10728, roller 10728 employs an end grooving deformation design to reduce boundary stresses; specifically, for the roller 10728, when it is processed, the excircle of the roller 10728 and the inner hole of the roller are firstly ground, then the grooving processing of the ring grooves 10724 on the two axial end faces is carried out, after the grooving processing is finished, the excircle and the inner hole generatrix of the roller 10728 are naturally deformed into arc lines, the geometric stress concentration existing on the outer cylindrical surface of the roller and the side pressure effect of the inner hole of the roller 10728 can be effectively weakened in the rotation process of the roller 10728, the stress distribution of the inner and outer working surfaces of the roller assembly 1072 is balanced, and the probability of the seizing between the roller assembly 1072 and the roller pin 1073 is reduced. The roller bush 10722 and the roller 10728 are in interference fit, so that the relative speed between the moving surface of the roller bush 10722 and the roller pin 1073 is increased, and the end surface of the roller bush 10722 moves at high speed to form an effective dynamic pressure oil film with the roller pin 1073, thereby increasing the dynamic pressure lubrication effect and reducing the probability of seizure between the roller bush 10722 and the roller pin 1073; the roller 10728 and the thrust bearing 10723 are in interference fit, the relative speed between the moving surface of the thrust bearing 10723 and the boss 10714 is improved, the end surface of the thrust bearing 10723 moves at high speed to form an effective dynamic pressure oil film with the boss 10714, the boss 10714 and the thrust bearing 10723 can be prevented from being tightly attached, excessive abrasion caused by insufficient oil supply to the end surface of the thrust bearing 10723 is avoided, the dynamic pressure lubricating effect can be improved by the formation of the dynamic pressure oil film, and the possibility of clamping between the thrust bearing 10723 and the boss 10714 is reduced.

As shown in fig. 19, the outer surface of the roller pin 1073 is provided as a cylindrical surface, two- step kidney grooves 10731, 10732 are provided at two positions on the cylindrical surface, respectively, and the kidney grooves 10731, 10732 are provided at a middle position of the roller pin 1073; the arrangement of the slender kidney-shaped grooves ensures that the lubricating oil in the kidney-shaped grooves 10731 and 10732 has larger contact area with corresponding friction surfaces, and makes full use of the movement speed of corresponding movement surfaces to bring more lubricating oil into the bearing surface to form a dynamic pressure oil film, thereby forming a thicker lubricating oil film. The two sides of the kidney-shaped groove 10731 are kidney-shaped, so that the stress concentration caused by the grooving on the surface of the roller pin 1073 is reduced. The two- step waist grooves 10731 and 10732 increase the surface lubrication flow rate. A small-angle wedge-shaped groove with an angle of 5-10 degrees is formed between the outer-layer kidney-shaped groove 10731 and the outer surface of the roller bushing 10722, and oil holes 10733 and 10734 are formed in the inner-layer kidney-shaped groove 10732; the included angle of the two kidney-shaped grooves is 70-120 degrees (the actual value can be determined according to a simulation calculation result, and can be selected as 90 degrees in an example), and the two kidney-shaped grooves are positioned right above the pressure-bearing area, so that the influence of the kidney-shaped grooves on the surface on the area of the pressure-bearing area is reduced under the condition of ensuring that oil is fully supplied to a friction surface, the angle of the pressure-bearing area is larger, and the average pressure of an oil film in the pressure-bearing area is smaller; a small-angle convergent wedge is formed by the outer kidney-shaped groove 10731 and the corresponding friction surface, so that the extrusion effect in dynamic pressure lubrication is enhanced; the inner layer of the kidney-shaped groove 10732 is mainly used for storing more lubricating oil, so that the sufficient oil supply to the friction surface is ensured, the lubrication on the surface of the roller pin is not influenced even if the oil supply is poor in a short time, and the probability of system seizure is reduced when the lubrication system has problems; the two oil holes 10733, 10734 at the two positions communicate through the lubricant oil outlet passage, and the two oil holes 10733 and 10734 are disposed at 90 ° therebetween.

As shown in fig. 17, 18 and 34, the outer surface of the pilot piston 1071 is provided as a cylindrical surface on which a plurality of circumferential oil grooves 10729 and 10725, a first axial oil groove 10716 and a vertical groove 10717 are provided, the vertical groove 10717 is opened in the circumferential oil groove 10725, and the vertical groove 10717 communicates with the circumferential oil groove 10729 through the first axial oil groove 10716; and 1-10 chamfers are arranged between the two sides of the circumferential oil groove 10725 and the upper end and the lower end of the guide piston 1071, and the chamfers and the corresponding motion surfaces form a small-angle convergent wedge during motion, so that the extrusion effect in dynamic pressure lubrication is enhanced. The surface lubrication state of the guide piston 1071 is improved, a thicker dynamic pressure oil film is established, friction is reduced, and the seizure probability is reduced. According to relevant data and experiments, when the chamfer angle is too large (such as 45 degrees or 90 degrees), the chamfer angle cannot enhance lubrication, but has a scraping effect on a corresponding friction surface, so that surface lubricating oil is scraped off, and the lubricating effect is reduced. The cylindrical surface is further provided with an inclined hole 10718, and two ends of the inclined hole 10718 are respectively communicated with the circumferential oil groove 10725 and the inner wall of the second mounting hole 10712. A second axial oil groove 10719 is also provided on the cylindrical surface in communication with the circumferential oil groove 10725. The cylindrical surface is also provided with a first straight hole 10720 and a second straight hole 10721 which are connected, the first straight hole 10720 is communicated with the first axial oil groove 10716, and the second straight hole 10721 is communicated with the first mounting hole 10711; the first and second straight bores 10720 and 10721 supply the lower spring seat assembly 106 inside the pilot piston 1071 with oil, reducing wear on the corresponding moving surfaces. The excircle surface of the roller pin 1073 is provided with a lubricating oil inlet duct 10735, the lubricating oil inlet duct 10735 is arranged opposite to the inclined hole 10718, and the lubricating oil inlet duct 10735 is communicated with the lubricating oil outlet duct.

The outer circle surface of the roller pin 1073 is provided with a DLC coating; the DLC coating has high hardness, small friction coefficient, wear resistance and high temperature resistance, and when the lubrication between the roller bush 10722 and the roller pin 1073 is poor, a friction pair consisting of the DLC coating and the roller bush 10722 of the copper alloy bearing can still run well, so that the probability of seizure between the roller pin 1073 and the roller bush 10722 can be further reduced; the roller bushing 10722 is made of copper alloy. The thrust bearing 10723 is made of a copper alloy. Forced lubrication is employed between the roller pin 723 and the roller bushing 10722. Forced lubrication is employed between the thrust bearing 10723 and the boss 10714. The roller bushing 10722 and the thrust bearing 10723 are made of bronze alloy, and the friction characteristics of the bronze alloy such as low friction coefficient, good wear resistance, self-lubrication and impact resistance are utilized to improve the friction characteristics of the inner hole and the end face of the roller component 1072 when solid friction exists between the inner hole and the corresponding moving surface, so that the friction coefficient is reduced, the impact resistance is improved, and the bearing capacity is improved.

As shown in fig. 15, 16 and 20, the outer circle of the upper end surface, the outer circle of the lower end surface and the circumferential ring groove 1025 of the guide piston 1071 are provided with first chamfers 10741; a second chamfer 10726 is provided on the hole wall of the first mounting hole 10711. A tenth hole 10727 is provided in the hole wall of the second mounting hole 10712; an eleventh hole 10736 is provided on the outer circumferential surface of the roll pin 1073; a spring 10737 and a retaining pin 10738 are sequentially disposed within the eleventh hole 10736 with the retaining pin 10738 partially extending into the tenth hole 10727. The eleventh hole 10736 is provided for mounting the stopper pin 10738, so that the roller pin 1073 and the guide piston 1071 are relatively stationary, the number of the relatively moving surfaces of the roller pin 1073 and the roller 10728 is reduced, the speed of the relatively moving surfaces is increased, and the dynamic pressure lubrication effect is enhanced (the principle thereof is the same as that of the interference fit between the roller and the bush). Specifically, when the roller assembly 1072 and the roller pin 1073 are assembled to the guide piston 1071, the roller bush 10722 and the thrust bearing 10723 are first mounted to the roller 10728 by cold-fitting; then the spring 10737 and the stop pin 10738 are sequentially placed into the eleventh hole 10736 of the roller pin 1073; then, the roller assembly 1072 is placed at the lower part of the guide piston 1071, and a roller pin 1073 is sequentially passed through one side of the fourth hole at the lower end of the guide piston 1071, the inner hole of the roller assembly (specifically, the inner hole of the roller bush), and the other side of the fourth hole at the lower end of the guide piston; then, the stopper pin 10738 is pressed by hand to a height lower than the second mounting hole 10712 while pushing the roller pin 1073 until the stopper pin 10738 is sprung into the tenth hole 10727 of the guide piston 1071 by the spring 10737. That is, the lubricating oil that has flowed out of the injection pump body 101 flows into the circumferential oil groove 10725 through the second axial oil groove 10719, and then flows into the circumferential oil groove 10729 through the vertical groove 10717 and the first axial oil groove 10716, lubrication between the guide piston 1071 and the injection pump body 101 is achieved, and because the clearance between the guide piston 1071 and the center hole of the pump body 101 that is fitted thereto is small, the lubricating oil that has entered the second axial oil groove 10719 of the guide piston 1071 and the circumferential oil groove 10725 retains a certain pressure, and a lubricating oil film can be formed between the outer circumference of the guide piston 1071 and the center hole of the pump body 101; meanwhile, the lubricating oil portion in the second axial oil groove 10719 flows into the lubricating oil inlet pipe 735 through the inclined hole 10718 to penetrate deeply into the roller pin 1073, and then flows out to the outer circumferential surface of the roller pin 1073 through the oil holes 10733 and 10734 to deeply lubricate between the roller pin 1073 and the rolling bush 722, forming a lubricating oil film between the roller pin 1073 and the rolling bush 722.

The angle range of the first chamfer 10741 and the second chamfer 7100 is between 1-10 degrees, a small-angle convergent wedge shape can be formed when the guide piston 1071 is matched with a middle hole on the pump body 101, the extrusion effect in dynamic pressure lubrication is enhanced, the thickness of an oil film on the surface of the guide piston 1071 is increased during operation, and therefore the probability of seizure between the guide piston 1071 and the pump body 101 is reduced.

As shown in fig. 20 and 21, the lubricant oil inlet passage 10735 includes: a third radial oil passage 10739 provided in the radial direction of the roller pin 1073 and an axial oil passage 10740 provided in the axial direction of the roller pin 1073, the third radial oil passage 10739 being connected to the axial oil passage 10740; the axial oil passage 10740 communicates with the oil holes 10733, 10734 in the kidney groove 10732.

The high-pressure oil pump has the following effects:

(1) and the temperature of the existing mechanical adjusting mode can be solved by applying the electric control proportional valve 2 to carry out oil inlet adjustment on the heavy oil. Specifically, a cooling circulation oil passage is arranged in the electronic control proportional valve 2, so that cooling oil flowing in the pump body 101 enters the electronic control proportional valve 2, and the electronic control element in the electronic control proportional valve 2 is cooled specifically, so that the electronic control element of the electronic control proportional valve 2 is kept within a normal temperature range, and oil inlet throttling of the pump by using the electronic control proportional valve 2 is allowed. The electric control proportional valve 2 overcomes the defect of mechanical oil quantity adjustment, improves the precision, flexibility and response speed of oil supply flow adjustment, further realizes more accurate matching of the oil supply quantity of the pump and the operation working condition of the diesel engine, avoids performance reduction caused by insufficient oil supply, also reduces surplus flow during working, and further reduces the actual load of the pump;

(2) by additionally arranging the oil inlet valve assembly 1031, the high-pressure oil chamber 1041 of the plunger sleeve 1042 is quickly closed when the high-pressure oil chamber is changed from oil absorption to compression, so that the pressure of the relevant position in an oil inlet passage of the oil inlet valve seat 10311 is ensured to be stable, and cavitation erosion is effectively prevented;

(3) the leakage of heavy oil can be completely prevented by the small amount of lubricating oil in the second annular groove 10422 of the plunger matching member 104, and the corrosion of the leaked heavy oil to the important parts such as the plunger spring 105 below the plunger sleeve 1042 is prevented. In addition, this application seals heavy oil through a small amount of lubricating oil, can effectively reduce guide piston 1071's vertical height (do not need the longer seal section that traditional low-speed machine set up on guide piston 1071), and then reduces high-pressure oil pump's pump vertical height, alleviates high-pressure oil pump's total weight, learns according to the experiment, the scheme of this application, has reduced 1/3 with high-pressure oil pump's vertical height.

(4) The outer spring seat 1061 is of a boss type structure with a thin outer side and a thick middle part, and in operation, the outer spring seat 1061 mainly bears the pressure transmitted from the plunger 1043 to the upper ball 1062, and the stress field caused by the pressure is distributed in the outer spring seat 1061 in a tapered manner. The outer spring seat 1061 is in a boss shape corresponding to the outer spring seat, so that the mass of the outer spring seat 1061 can be reduced under the condition of meeting the strength, the moving mass is further reduced, and a design space is provided for a middle spherical surface and an oil passage by a thicker part between bosses;

(4) form the sphere cooperation between outer spring seat 1061 and the last spheroid 1062, when setting up the lower spring holder subassembly 106 that has the sphere between plunger 1043 and guide piston 1071, even there is great depth of parallelism error guide piston 1071 up end and plunger 1043 afterbody terminal surface, but the sphere can automatic angle modulation, make the contact surface between ball 1062 and the outer spring seat 1061 keep abundant contact, eliminate local contact, make whole atress balanced, alleviate the too big trend of local stress. Meanwhile, the resultant force passes through the center of the spherical surface, so that the bending moment of the accessory is eliminated, the dynamic characteristic is optimized, and the bearing capacity of the system is improved.

(5) The spherical hole 10612 provides lubricating oil for the spherical surface to lubricate the spherical surface, and the lubricating oil is utilized to form an elastic flow lubricating effect on the spherical surface, so that the wear rate is reduced, the contact stress is reduced, the fretting damage is reduced, and the bearing capacity and the fatigue strength of the spherical surface are improved;

(5) the outer surface of the outer spring seat 1061 forms a conical surface, and the lubricating oil outlet channel 10615 is formed on the outer conical surface of the outer spring seat 1061, so that the plunger spring 105 can be prevented from covering the flow area of the lubricating oil outlet channel 10615, and the flow area is not influenced by the position of the plunger spring 105;

(6) the inner spring seat 1063 is provided with the guide conical surface 10637, so that the centering property can be improved, the inner spring seat 1063 and the upper ball 1062 can be automatically aligned even if the ball is impacted, and the uneven stress trend is improved;

(7) the communicating hole 10713 arranged in the guide piston 1071 makes the lubricating oil above the guide piston 1071 evenly distributed in the middle right above the second mounting hole 10712 of the roller 10728 when flowing down from the communicating hole 10713, the lubricating oil is evenly distributed on the bus of the roller, and the distribution of the lubricating oil on the surface of the roller 10728 is not influenced by positive and negative rotation (can be evenly distributed); the vertical stress distribution of the guide piston is improved, namely the pressure of the plunger 1043 is distributed to a thicker position around the communicating hole 10713, so that the integral stress is balanced, the maximum stress is reduced, and the reliability of the bearing capacity of the system is improved; when the guide piston 1071 is matched with the outer spring seat 1061 during pump assembly, the lubricating oil outlet oil channel 10615 of the outer spring seat 1061 is communicated with lubricating oil leaked above the plunger and barrel assembly 104, so that oil hole blockage by a spring can be avoided, and the flow area of the lubricating oil is increased;

(8) the first radial oil groove 10715 that sets up on the boss 10714 is full of the lubricating oil, for the plane of motion (roller components terminal surface) provides abundant lubricating oil, utilizes the terminal surface rate of motion of gyro wheel 10728 to form the dynamic pressure oil film at the gyro wheel 10728 terminal surface, separates guide piston 1071's boss 10714 and roller components 1072 terminal surface, reduces wearing and tearing, reduces coefficient of friction. A first radial oil groove 10715 is formed on boss 10714 of guide piston 1071 as compared with that formed on roller assembly 1072. The guide piston 1071 can not rotate relatively, the distribution of the high and low pressure oil film area on the friction surface is relatively static, the axial direction of the roller component 1072 is relatively static;

(9) the included angle of two-step kidney-shaped grooves 10731 and 10732 arranged in the roller pin 1073 is 70-120 degrees and is positioned right above the pressure-bearing area, so that under the condition of ensuring sufficient oil supply to the friction surface, the influence of the kidney-shaped grooves on the surface on the area of the pressure-bearing area is reduced, the angle of the pressure-bearing area is larger, and the average pressure of an oil film in the pressure-bearing area is smaller; a small-angle convergent wedge is formed by the outer kidney-shaped groove 10731 and the corresponding friction surface, so that the extrusion effect in dynamic pressure lubrication is enhanced; the inner layer of the kidney-shaped groove 10732 is mainly used for storing more lubricating oil, ensures sufficient oil supply to the friction surface, does not influence the lubrication of the surface of the roller pin even if the oil supply is poor in a short time, and reduces the probability of system seizure when a lubrication system has problems.

Referring to fig. 24 and 25, the low-speed machine integral common rail is suitable for working at the temperature of 200 ℃ and the pressure of 150MPa, and has a low-pressure circulation function, a pressure limiting function and a pressure maintaining function. The device mainly comprises a common rail pipe 12, a flow limiting valve assembly 13, an oil inlet end cover 121, an end cover 122, a circulating valve assembly 16, a pressure limiting valve assembly 18, a sensor mounting seat 127, a sensor 124, a flow limiting valve mounting seat 125, a support 126 and the like. The common rail pipe 12 is of a cylindrical structure, a plurality of first notches 1203 are formed in one side of the outer circle of the common rail pipe 12, and the first notches 1203 are respectively used for installing the flow limiting valve assembly 13, the sensor mounting seat 127 and the pressure limiting valve assembly 18. On the common rail pipe 12, a second cutout 1204 is provided on the other side opposite to the first cutout 1203, and the second cutout 1204 is used for mounting the bracket 126. Meanwhile, end caps 122 and oil inlet end caps 121 are installed on both sides of the common rail pipe 12.

Firstly, the low-speed engine integral common rail is mounted by using two waist-shaped holes arranged on the bracket 126 to mount the bolt 128, and the bolt 128 passes through the waist-shaped holes to be fixed on the whole machine, so that the low-speed engine integral common rail is mounted. In addition, considering that the number of engine cylinders of the low-speed diesel engine is large and the number of corresponding brackets 126 is large, the brackets 126 are provided with kidney-shaped holes, so that the installation and adjustment among the brackets 126 are facilitated, and the interference is prevented. Meanwhile, the bracket 126 and the common rail pipe 12 are fixed by four screws 129, and cylindrical pins are arranged on the four screws for facilitating the positioning of the common rail pipe 1.

The common rail pipe 12 in this embodiment adopts an integral structure, and the oil inlet pipeline 1201 penetrating through both ends is arranged in the common rail pipe, so that the processing on both sides of the common rail pipe 12 is facilitated, the processing difficulty is reduced, and the end cover 122 and the oil inlet end cover 121 for realizing the sealing of the common rail pipe 12 are arranged on both sides. Meanwhile, the end cover 122 and the oil inlet end cover 121 are respectively sealed with the common rail pipe 12 in a conical surface mode, the fixing of the end cover 122 and the common rail pipe 12 and the fixing of the oil inlet end cover 121 and the common rail pipe 12 are achieved through bolts, and the sealing performance can be improved.

The integral common rail of the low-speed engine has the functions of pressure limiting and pressure maintaining, the pressure limiting valve assembly 18 is installed on the first cut 1203 arranged on the common rail pipe 12, when the pressure in the oil inlet pipeline 1201 of the common rail pipe 12 exceeds the limiting pressure of the pressure limiting valve assembly 18, the pressure limiting valve assembly 18 overcomes the pre-tightening force of the second pressure regulating spring 185 inside to open, and through the self-adjusting function, when the pressure limiting valve assembly 185 is stable, the rail pressure is kept at a certain pressure value. The diesel engine can be ensured to operate in a low-speed and low-torque state.

Further, considering that the low-speed engine integrated common rail combustion medium of the present invention uses low-quality fuel oil, in order to prevent the low-speed engine common rail internal combustion oil from solidifying after the diesel engine is shut down, the pneumatically controlled circulation valve assembly 16 is installed on the end cover 122, the circulation valve assembly 16 includes parts such as the first valve core 161, the first valve body 162, the gland 167, and the first pressure regulating spring 169, the gland 167 is fixed on the first valve body 162 by the screw 1632, after the engine is shut down, the rail pressure in the oil inlet pipe 1201 of the common rail pipe 12 is reduced to be lower than the spring force of the first pressure regulating spring 169, the spring force pushes the first valve core 161 to move downward, when the first valve core 161 moves to the bottom dead center, the conical surface sealing between the first valve core 161 and the first valve body 162 in the circulation valve assembly 16 is released, and the heavy oil in the oil inlet pipe 1201 of the common rail pipe 12 can flow back to the oil tank through the first oil return passage 1605, the second oil return passage 1606, and the fuel circulation is realized. When the engine is just started, the air inlet 1630 of the circulation valve assembly 16 is filled with compressed air, after the compressed air enters the first cavity, the first valve element 162 is pushed to move in the direction of the top dead center under the action of the compressed air, and when the first valve element 162 moves upwards to the top dead center, a conical surface seal is formed between the first valve element 162 and the first valve body 161, so that the rail pressure in the common rail pipe 12 is established.

The low-speed engine integrated common rail is used in a high-pressure common rail system of a diesel engine, the common rail pipe 12 is always in a high-pressure state in the working process, in order to ensure the safety of personnel and the diesel engine, a sensor 124 for detecting the pressure in an oil inlet pipeline 1201 in the common rail pipe 12 is arranged on the common rail pipe 12, the pressure is monitored in real time, and in order to ensure the accuracy of the pressure, two sensors 124 are arranged and are used as backups for each other.

In addition, a flow limiting valve assembly 13 is arranged between the common rail pipe 12 and the electric control fuel injector 15, the flow limiting valve assembly 13 mainly comprises a second valve core 133, a valve seat 131, a second valve body 132, a second pressure regulating spring 135 and other parts, when a high-pressure oil pipe between the flow limiting valve assembly 13 and the electric control fuel injector 15 is broken or the electric control fuel injector 15 excessively injects fuel, the second valve core 133 in the flow limiting valve assembly 13 overcomes the spring force of the second pressure regulating spring 135 to be attached to the second valve body 132 through pressure difference, and the high-pressure fuel in the oil inlet pipeline 1201 of the common rail pipe 12 is blocked from flowing into the electric control fuel injector 15.

In addition, because the common rail works under the high-temperature, high-pressure and poor-quality fuel oil states, the common rail pipe 12 and the high-pressure sealing surfaces of all parts are considered to be possible to cause high-pressure fuel oil leakage, so that the environment is polluted and the personal safety of workers is damaged, and oil return holes are formed in all high-pressure sealing positions and used for collecting return oil. Specifically, an oil return pipe 1202 is arranged in the common rail pipe 12, and the oil return pipe 1202 is communicated with the first cut 1203 and used for collecting high-pressure sealing leakage return oil of the common rail pipe 12, the flow limiting valve assembly 13 and the pressure limiting valve assembly 18.

Further, the flow limiting valve assembly 13 is mounted at one of the first cutouts 1203 through the flow limiting valve mounting seat 125, the pressure limiting valve assembly 18 is mounted at one of the first cutouts 1203 through the pressure limiting valve mounting seat 123, the sensor 124 is mounted at one of the first cutouts 1203 through the sensor mounting seat 127, and the flow limiting valve mounting seat 125, the pressure limiting valve mounting seat 123 and the sensor mounting seat 127 are respectively provided with a sealing ring to prevent fuel leakage. Similar to the installation principle of the pressure limiting valve assembly 18, the sensor installation seat 127 and the flow limiting valve installation seat 125 are firstly fixed on the common rail pipe 1 by means of screw fixation, and then the installation of the sensor 124 and the flow limiting valve assembly 13 is realized by means of screws.

Specifically, referring to fig. 26, 27 and 28, the circulation valve assembly 16 includes: a first valve body 161 fixed to the end cap 122, a first valve spool 162, a nut 1614, a lower spring seat 164, a seal ring, a gland 167, and an oil return joint 168. The first valve body 161 is provided with an axial middle hole and two first oil return ducts 1605, the axial middle hole is communicated with the oil inlet pipeline 1201 in the common rail pipe 12, high-pressure fuel oil in the oil inlet pipeline 1201 in the common rail pipe 12 can enter an axial through hole of the circulating valve assembly 16, two first seal ring grooves 1620 are arranged at positions where the two first oil return ducts 1605 are arranged at the top of the first valve body 161, a first air inlet passage 1608 communicated with the axial middle hole is further arranged on the first valve body 161, a second seal ring groove 1622 is arranged in the circumferential direction of the first air inlet passage 1608, and a second seal ring 1631 used for improving a sealing effect is arranged in the second seal ring groove 1622. The first valve core 162 is arranged in an axial middle hole of the first valve body 161, a first sealing conical surface 1611 is arranged at the top of the first valve core 162, and an external thread 1612 is arranged on the upper part of the first sealing conical surface 1611; the lower spring seat 164 is disposed on the first sealing tapered surface 1611 after passing through the external threads 1612, and a second sealing tapered surface 1613 matching with the first sealing tapered surface 1611 is disposed on the lower portion of the lower spring seat 164. The nut 1614 is sleeved on the external thread 1612 and presses the lower spring seat 164. The first pressure adjusting spring 169 is disposed on the nut 1614 and fixed to the lower spring seat 164. The gland 167 is disposed on the top of the first valve body 161, and is provided with two second oil return channels 1606 communicated with the two first oil return channels 1605, and the middle of the gland is further provided with a threaded hole 1603 for installing the oil return joint 168, a first sealing plane 1615 is disposed at an orifice of the threaded hole 1603, the bottom surface of the gland 167 is provided with a second air inlet channel 1629 communicated with the first air inlet channel 1608, an air inlet 1630 is circumferentially disposed, and the air inlet 1630 is communicated with the second air inlet channel 1629. The oil return connection 168 is arranged in a threaded hole 1603 on which a second sealing plane 1616 is arranged to cooperate with the first sealing plane 1615.

As shown in fig. 28 and 29, initially when compressed air is introduced into the air inlet 1630, the first valve element 162 moves upward, the lift H2 between the bottom end surface of the first valve element 161 and the bottom end surface of the first valve element 162 is at the maximum lift, at this time, no oil returns exist in the first oil return passage 1605, when the oil inlet pressure at the bottom of the first valve element 162 is lower than the opening pressure of the first pressure regulating spring 169, the first valve element 162 moves downward under the spring force of the first pressure regulating spring 169, at this time, the lift H2 between the bottom end surface of the first valve element 161 and the bottom end surface of the first valve element 162 is 0, the first oil return passage 1605 starts to return oil, low-pressure fuel circulation is achieved, and high-pressure heavy oil in the common rail pipe 12 flows back to the oil tank through the first oil return passage 1605, the second oil return passage 1606 and the third oil return.

Specifically, the axial center hole of the first valve body 161 includes: and a first middle hole 1601 is matched with the outer circle of the first valve core 162, and a third sealing ring groove 163 is arranged on the hole wall of the first middle hole 1601 and used for installing a third sealing ring 1624. In the present application, it can be determined based on the above principle that before the circulation valve assembly 16 is inflated, the first valve element 162 moves downward to the bottom dead center position under the action of the first pressure regulating spring 169, and at this time, no sealing relationship is established between the first valve element 162 and the first valve body 161; at the initial moment of the engine just starting, the rotating speed of the high-pressure oil pump is low, at this time, the flow rate of the high-pressure fuel pumped into the common rail pipe 1 by the high-pressure oil pump is small, and the pressure in the oil inlet pipe 1201 of the common rail pipe 1 cannot be built quickly due to the fact that the conical surface sealing is not formed between the first valve core 162 and the first valve body 161. Therefore, in order to quickly build the pressure in the common rail 12, a tapered surface seal needs to be formed between the first valve element 162 and the first valve body 161, and thus, a forward (upward) movement of the first valve element 162 needs to be realized, at this time, the first valve element 162 needs to receive an external forward force, in this example, compressed air is used as a power source of the external forward force, specifically, a closed volume chamber (first cavity) needs to be designed on the first valve body 161 for bearing the compressed air, as shown in fig. 29, a first sealing tapered surface 1611 and an external thread 1612 are arranged on the first valve element 162, and a lower spring seat 164, a nut 1614 and a first pressure regulating spring 169 are sequentially arranged thereon. The lower spring seat 164 and the first middle hole 1601 of the first valve body 161 form a first cavity for carrying compressed air, when the pressure of the compressed air is sufficiently greater than the pre-tightening force of the first pressure regulating spring 169, the first valve spool 162 moves upward, at this time, the lift H2 of the bottom end surface of the first valve body 161 and the bottom end surface of the first valve spool 162 is at the maximum, the first oil return passage 1605 has no oil return, when the pressure of the fuel at the lower portion of the first valve spool 162 is sufficiently greater, the introduction of the compressed air is stopped, and at this time, the lift H2 of the first valve spool 162 is mainly maintained by the oil inlet.

In order to form a closed volume chamber in the first cavity, a third sealing ring 1624 is mounted on a third sealing ring groove 163 formed in the first center hole 1601 coupled to the outer circumference of the first valve core 162, so as to prevent the compressed air from leaking to the first return passage 1605. Similarly, a fourth seal ring groove 1625 is provided on the lower spring seat 164 and the axial center hole fitting wall for mounting a fourth seal ring 1627. In addition, a second sealing tapered surface 1613 is provided at a lower portion of the lower spring seat 164 to cooperate with the first sealing tapered surface 1611 to prevent leakage of compressed air.

In this application, compressed air enters the first cavity after passing through the air inlet 1630, the second air inlet 1629 and the first air inlet 1608, and in order to prevent air leakage, a first sealing ring 1628 is disposed at a joint of the first air inlet 1608 and the second air inlet 1629.

As shown in fig. 28 and 29, after the compressed air is introduced into the first cavity, the lower spring seat 164 moves forward, and in order to ensure that the lower spring seat 164 moves forward together with the first valve element 162, the lower spring seat 164 is pressed against the first valve element 162 by the nut 1614 to be integrated, and in addition, when the lower spring seat 164 passes through the external thread 1612 of the first valve element 162, the second sealing conical surface 1613 on the lower spring seat 164 is prevented from being damaged by the external thread 1612, and the diameter of the fourth central hole 1618 on the lower spring seat 164 must be larger than the outer diameter of the external thread 1612.

The first spool 162 reduces resistance to movement during forward movement, and the outlet passage 1623 and the third central bore 1617 in the lower spring seat 164 communicate with a second cavity formed by the second central bore 1602 in the first valve body 161 for venting air from the second cavity.

Further, considering that the fitting portion 1626 of the lower spring seat 164 is mounted with the fourth seal ring 1627, the mounting is convenient when the lower spring seat 164 is mounted into the second central hole 1602 of the valve body 1, without damaging the fourth seal ring 1627, the guide portion 1619 is provided at the orifice of the second central hole 1602, and the full angle of the guide portion 1619 is generally set to 30 ° to 40 °.

As shown in fig. 25, a first sealing ring groove 1620 is provided at the joint of the first oil return passage 1605 and the second oil return passage 1606 for installing a first sealing ring 1628 to prevent low-pressure fuel leakage, and similarly, in order to prevent fuel leakage between the oil return joint 168 and the gland 167, a second sealing plane 1616 is provided on the oil return joint 168 to match with the first sealing plane 1615 on the gland 167.

A third cavity is formed by a threaded hole 1603 arranged on the gland 167 and the bottom surface of the oil return joint 168, the third cavity is communicated with a third oil return passage 1607 (the third oil return passage 1607 is communicated into the oil tank through a pipeline) arranged on the oil return joint 168 and a second oil return passage 1606, and the flow area of the third cavity is larger than that of the second oil return passage 1606, so that fuel oil can be discharged in time.

When the engine is stopped, the fuel pressure at the bottom of the first valve core 162 (namely, the fuel pressure in the oil inlet pipeline 1201 of the common rail pipe 12) is reduced to the opening pressure of the first pressure regulating spring 169, the first valve core 162 moves reversely, at the moment, H2 is 0, because the H1 is larger than H2, the lower spring seat 164 cannot collide with the second middle hole 1602, at the moment, the first cavity has a certain volume, so that when compressed air is introduced into the first cavity when the engine is started, the first valve core 162 can move forward rapidly, and the fuel pressure at the bottom of the first valve core 162 can build pressure rapidly.

The circulating valve assembly 16 is used in a high-pressure common rail system of a low-speed diesel engine, and the combustion medium is poor-quality fuel. In order to ensure the service life and the functional reliability of the flow limiting valve, the first valve core 162 is made of high-speed tool steel materials, DLC is plated on a matching section, the first valve body 161 is made of high-strength structural steel and is subjected to nitriding treatment, and the high-temperature resistance and corrosion resistance of the circulating valve are ensured by adopting the materials and a heat treatment method.

The above-mentioned circulating valve assembly 16 for the common rail pipe 12 is installed on the common rail pipe 12 with high pressure, and its principle mainly utilizes the compressed air and the elastic force of the first pressure regulating spring 169 to realize the upward pushing and downward pushing of the first valve core 162, when the air inlet 1630 is introduced with the compressed air, the first valve core 162 and the lower spring seat 164 are connected into a whole by the nut 1614 to move upward under the action of the air pressure, at this time, H2 is at the maximum value, the first oil return passage 1605 has no oil return, the fuel at the bottom of the first valve core 162 builds the pressure in the motion process of the high pressure oil pump, when the fuel pressure reaches a certain value, the compressed air is cut off, at this time, the H2 is at the maximum value and is mainly. When the engine is stopped, when the pressure in the common rail pipe 12 is reduced to be lower than the spring force of the first pressure regulating spring 169, the first valve core 162 is pushed reversely, and at the moment, low-pressure fuel enters the first oil return passage 1605 and then sequentially flows into the fuel tank from the second oil return passage 1606 and the third oil return passage 1607, so that the circulation effect of the fuel is realized, the solidification of the fuel is avoided, and the corrosion of parts can be prevented.

Specifically, with reference to fig. 32 and 33, for the pressure limiting valve assembly 18 in the present embodiment, it includes: the third valve body 181, the third valve core 182, the second O-shaped sealing ring 183, the bolt 184, the third pressure regulating spring 185, the oil pipe joint 186 and the pressure regulating gasket 187. The fourth stage hole 18105 in the third valve body 181 is provided with the third valve core 182, the second taper angle 202 of the third valve core 182 presses against the sealing seat surface 18103 (referring to the hole wall of the second stage hole 18102) of the third valve body 181, and the third valve core 182 presses through the tubing connector 186 and the third pressure regulating spring 185. The lower part of the oil pipe joint 186 is provided with a sealing ring groove, and a second O-shaped sealing ring 183 is arranged in the sealing ring groove, so that the sealing effect is improved, and the effect of preventing fuel oil leakage is achieved. The middle part of the oil pipe joint 186 is provided with multi-stage counter bores 18601 (first counter bores) and 28602 (second counter bores) and an oil outlet 18603, the outer circle of the upper part is provided with threads, and the oil pipe joint 186 is arranged on the third valve body 181 through a bolt 184. And a pressure regulating gasket 187 and a third pressure regulating spring 185 are arranged in a second counter bore 18602 in the middle of the oil pipe joint 186.

Furthermore, the third valve body 181 is provided with a plurality of holes 18101 (first hole), 18102 (second hole), 18104 (third hole) and 18105 (fourth hole), wherein the second hole 18102 is a small throttling hole, and the first hole 18101 is larger than the second hole 18102, so that the depth of the throttling hole is reduced, and the processing difficulty is reduced. The angle between the second-stage hole 18102 of the third valve body 181 and the first-stage hole 18101 (or the third-stage hole 18104) is set to 59 ° (corresponding to the sealing seat surface 18103 of the third valve body being set to 59 °), so that the third valve body is ensured to be sealed with the second taper angle 18202 of the third valve core 182 within 1 ° deviation, and the sealing performance is good. The hole diameter of the third stage hole 18104 of the third valve body 181 is set larger than the hole diameters of the second stage hole 18102 and the fourth stage hole 18105 forThe fuel pressure is stored. The fourth stage hole 18105 of the third valve body 181 has a hole diameter set to

If the aperture of the fourth-stage hole 18105 is too small, the processing difficulty is high, and the use precision cannot be guaranteed; if the diameter of the fourth stage hole 18105 is too large, the depth of the fourth stage hole 18105 is increased due to the length requirement of the third valve element 182, the machining difficulty of the sealing seat 18103 is increased, the precision cannot be guaranteed, and the problem of difficult measurement is caused. The third valve body 181 is made of a high-strength structural steel material and is nitrided, high pressure resistance of the third valve body 181 is guaranteed by selecting a high-strength material, and the third valve body 181 can work in a low-speed engine heavy oil environment and is corrosion-resistant by nitriding.

Referring to fig. 33, the head of the third valve element 182 is set to have two taper angles (a first taper angle 18201 and a second taper angle 18202), and the first taper angle 18201 is set to have an obtuse angle of 120 °, so that the reliability of the third valve element 182 is increased, the flow area of the head of the third valve element 182 is increased, and the cavitation is reduced. The second taper angle 18202 of the third spool 182 is set to be an acute angle of 60 °, and in order to ensure good sealing performance, the taper angle of the third spool 182 is generally set to be 60 ° and 90 °, so that the design difficulty of the third pressure regulating spring 185 is reduced in consideration that the lift of the needle valve at 60 ° is smaller than that at 90 ° under the same flow area.

Referring to fig. 33, two symmetrical second flats 18203 are milled into a third outer circle 18204 in the middle of the third spool 182, the flow area of the second flats 18203 is larger than the flow area of the second-stage orifice 18102 of the third valve body 181, and a second gap for fuel to pass is formed between the second flats 18203 of the third spool 182 and the fourth-stage orifice 18105, and the fuel flow area in the second gap is larger than the fuel flow area in the second-stage orifice 18102. Referring to fig. 33, a second small outer circle 18206 of the upper portion of the third spool 182 is used for positioning the third pressure regulating spring 185, and the third pressure regulating spring 185 is sleeved on the second small outer circle 18206.

The third valve core 182 is made of high-speed tool steel material, and a third outer circle 18204, which is matched with the fourth-stage hole 18105 of the third valve body 1, of the third valve core 182 is plated with a DLC layer in a matched mode, so that the strength requirement of the third valve core 182 is guaranteed, the third valve core is resistant to corrosion in a heavy oil environment, and the third valve core 182 is more wear-resistant due to the plating layer.

Further, referring to FIG. 32, the third spool 182 and the third spool 181 are provided with a range limit h1 to ensure that the third spool 182 moves within a range that would otherwise cause the third pressure regulating spring 185 to compress and disable the third pressure regulating spring 185 from returning.

Further, referring to fig. 32, an overlapping area h is provided between the third valve element 182 and the third valve element 181, and when the third valve element 182 is opened and closed, at the moment when the overlapping area h is generated between the third valve element 182 and the third valve element 181, fuel cannot flow out through the second flat 18203, pressure is formed in the third-stage hole 18104, a force opposite to the moving direction is generated on the third valve element 182, the impact force of the third valve element 182 on the sealing seat surface 18103 of the third valve element 181 is reduced, and the service lives of the third valve element 181 and the third valve element 182 are ensured.

For the constrictor valve 18, the operating principle is: the pressure limiting valve assembly 18 is applied to a high-pressure common rail fuel injection system of a marine low-speed diesel engine and can work under the high pressure of 150MPa and the high temperature of 200 ℃. The pressure limiting valve assembly 18, which serves as a safety feature for the common rail system, is normally inactive and is therefore also referred to as a pressure relief valve. When the rail pressure control of the oil inlet pipeline 1201 of the common rail pipe 12 is abnormal, the pressure exceeds the opening pressure P of the pressure limiting valve assembly 18_LAt this time, the pressure limiting valve assembly 18 opens for pressure relief. Specifically, the third spool 182 enters the first-stage hole 18101 by the oil pressure of the high-pressure fuel supplied in the oil inlet pipe 1201 of the common rail pipe 12, and then enters the second-stage hole 18102, and further pushes the third spool 182 upward to unseal the third spool 182 and the third valve body 181. The third spool 182 moves upward under the action of oil pressure until the conical surface between the second taper angle 18202 and the sealing seat surface 18103 is relieved, and the high-pressure fuel in the oil inlet pipe 1201 of the common rail pipe 12 partially passes through the first-stage hole 18101, the second-stage hole 18102, the third-stage hole 18104, the fourth-stage hole 18105, the groove 18205, the first counter bore 18601 and the second counter bore 18602, finally enters the oil return pipe from the oil outlet 18603, and finally enters the oil return pipeReturning to the tank, the pressure in the inlet line 1201 of the common rail 12 is reduced. After the third valve core 182 is opened, the pressure in the oil inlet pipeline 1201 of the common rail pipe 12 is reduced, so that the oil inlet amount (the oil amount pumped into the common rail pipe 12 by the high-pressure oil pump) of the fuel system and the oil outlet amount passing through the pressure limiting valve assembly 18 gradually reach a stable state, the system pressure gradually approaches to the stable pressure Ps, and the diesel engine is ensured to limp to return to the port in a failure mode under the stable pressure Ps. The pressure limiting valve assembly 18 is closed (lower than the opening pressure) only when the common rail pressure drops to a certain level.

In the embodiment, the flow limiting valve assembly 13 is installed between the common rail 12 and the electronic control fuel injector 15, and when a high-pressure fuel pipe leaks or the electronic control fuel injector 15 leaks and abnormal injection occurs, the fuel supply of the electronic control fuel injector 15 can be cut off, so that the problems of fire explosion, personnel safety and the like are prevented.

As shown in fig. 30 and 31, the flow limiting valve assembly 13 specifically includes: the valve seat 131 is provided with a first flat 13104 for oil return on the large excircle, a first oil inlet 13101 is arranged in the middle, the first oil inlet 13101 is communicated with an oil inlet pipe 1201 of the common rail pipe 12, and a fifth sealing conical surface 13102 is arranged at the bottom; a second valve body 132, a small end surface 13201 of which is fixed to a large end surface 13105 of the valve seat 131, and which is provided with a second axial through hole 13209 in the axial direction, the second axial through hole 13209 penetrating through the upper and lower end surfaces thereof, and the valve seat 131 being partially press-fitted in the second axial through hole 13209 by press-fitting; the second valve core 133 passes through the second axial through hole 13209 and is fixed on the upper end surface of the first small outer circle 13106 of the valve seat 131, an axial blind hole 13302 communicated with the first oil inlet hole 13101 and four transverse throttle holes 13304 communicated with the axial blind hole 13302 are formed in the second valve core 133, and a third sealing conical surface 13305 and a fourth sealing conical surface 13306 are formed in the upper portion of the second valve core 133; the second valve body 132 has four fourth oil return passages 13210 communicated with the first flat 13104, the second valve body 132 is provided with a first sealing seat surface 13206 matched with the third sealing conical surface 13305, and an oil outlet 6207 and a second sealing seat surface 13208 are sequentially arranged at positions close to the fifth sealing seat surface 6206; the second valve body 132 has a first fitting portion 13203 fitted with the first small outer circle 13106 of the valve seat 131 and a second fitting portion 13204 fitted with the first outer circle 13301 of the second spool 133; a cavity is formed between the second fitting portion 13204 and the second spool 133, and the cavity communicates the transverse throttle hole 13304 with the axial blind hole 13302; and a second pressure regulating spring 135 inserted into the cavity and fixed to an upper end surface of the first outer circumference 13301 of the second spool 133.

In this embodiment, the second axial through hole 13209 includes a first hole, a second hole, a third hole 13205, a fourth hole 13207, a fifth hole, and a sixth hole, which are sequentially connected from top to bottom; the valve seat 131 is partially press-fitted into the first hole; the second valve spool 133 is fitted in the second hole, and the upper portion of the second valve spool 133 and the upper portion of the second hole form a cavity; the wall of the third bore 13205 forms a third sealing taper 13305; a second sealing seat surface 13208 used for forming a seal with the oil inlet end of the oil pipe of the electronic control oil injector 15 is formed on the hole wall of the fifth hole; the sixth hole has a larger pore size than the first, second, third, fourth, and fifth holes 13205, 13207.

The fourth hole 13207 serves as an oil outlet, and when the first seal seat surface 13206 and the third seal tapered surface 13305 are unsealed, the fuel in the first oil inlet hole 13101 flows out into the fourth hole 13207, and further flows out.

When the inlet pressure of the transverse throttle 13304 on the side of the axial blind hole 13302 exceeds a certain value of the cavity pressure, the second spool 133 moves upward under the action of the inlet pressure, and the third sealing conical surface 13305 contacts the first sealing seat surface 13206 to form a conical surface seal, so that fuel is blocked from entering the oil outlet.

Specifically, as shown in fig. 29, the second valve element 133 has a third sealing taper surface 13305, and the second valve body 132 has a first sealing seat surface 13206 that forms a taper seal with the third sealing taper surface 13305, so that when the inlet pressure of the transverse throttle hole 13304 on the axial blind hole 13302 side exceeds a certain value of the cavity pressure, the third sealing taper surface 13305 forms a taper seal relationship with the first sealing seat surface 13206 to block the fuel from entering the oil outlet opening 6207; conversely, when the inlet oil pressure at the side of axial blind bore 13302 of cross-restriction 136304 does not exceed a certain value of cavity pressure, third sealing cone 13305 and first sealing seat surface 13206 unseal. For the fourth sealing tapered surface 13306, during the upward movement of the second valve spool 133 under the oil pressure of the oil inlet pressure, the fourth sealing tapered surface 13306 first contacts the first sealing seat surface 13206, but a gap is formed between the fifth sealing seat surface 6305 and the first sealing seat surface 13206, and the gap can be filled with a certain amount of fuel, so that the rapid movement of the second valve spool 133 is buffered, and the second valve spool 133 is prevented from moving too fast to generate a large impact with the second valve body 132.

As shown in fig. 25, the restrictor valve assembly 13 is mounted on the common rail pipe 12 via a restrictor valve mounting seat 125, and the restrictor valve mounting seat 125 is fixed to the common rail pipe 12 via screws; a screw mounting hole 13211 is designed on the second valve body 132, the second valve body 132 of the flow limiting valve assembly 13 is fixed on the flow limiting valve mounting seat 125 by passing a screw through the screw mounting hole 13211, and an oil hole communicated with the first oil inlet hole 13101 is formed in the flow limiting valve mounting seat 125, so that high-pressure fuel in the oil inlet pipe 1201 of the high-pressure common rail pipe 12 can enter the first oil inlet hole 13101. The valve seat 131 is designed with a fifth sealing cone 13102 for sealing the high pressure fuel between the restrictor valve assembly 13 and the high pressure common rail 12. The second valve body 132 is designed with a second sealing seat surface 13208 for sealing the conical surface between the flow limiting valve assembly 13 and the oil pipe of the electronic fuel injector 15.

As shown in fig. 30, a seal groove is formed on an outer surface of the second valve body 132 for receiving the first O-ring 136, wherein the first O-ring 136 is formed on the outer surface of the second valve body 132 to enhance a sealing performance between the second valve body 132 and an external member when the second valve body 132 is assembled into the external member.

As shown in fig. 30, the valve seat 131 is provided with a first flat 13104, and the first flat 13104 is communicated with four fourth oil return passages 13210 to collect fuel leaked from the fifth sealing tapered surface 13102, the large end surface 13105 and the small end surface 6202 of the valve seat 131, and the second sealing seat surface 13208 of the second valve element 132.

As shown in fig. 30, in order to ensure the sealing between the small end surface 13201 of the second valve body 132 and the large end surface 13105 of the valve seat 131, a large bevel 13202 is provided to reduce the contact area between the large end surface 13105 and the small end surface 13201, thereby enhancing the sealing property.

To facilitate the integral installation of the constrictor valve assembly 13 on the high-pressure common rail, the first small outer circle 13106 of the valve seat 131 has the same diameter as the first mating portion 13203 of the second valve body 132 and is mated in a transitional manner. A sunk groove 13103 is formed at the intersection of the large end face 13105 and the first small outer circle 13106.

As shown in fig. 30, in order to realize the flow restriction valve function, the transverse throttle holes 13304 of the second spool 133 are provided with 4, and the area of the 4 throttle holes is smaller than the area of the axial blind hole 13302, the area of the fourth hole (oil outlet hole) 6207, and the flow area formed by the fourth seal tapered surface 13306 and the first seal seat surface 13206.

As shown in fig. 30, the fourth sealing taper surface 13306 of the second valve spool 133 is disposed at the rear of the second valve spool 133, adjacent to the third sealing taper surface 13305, and the angle of the fourth sealing taper surface 13306 is greater than the angle of the third sealing taper surface 13305, increasing the flow area between the fourth sealing taper surface 13306 and the first sealing seat surface 13206.

In order to prevent fuel from leaking to the first fitting portion 13203 in the cavity formed between the second spool 133 and the second fitting portion 13204, the clearance between the first outer circle 13301 and the second fitting portion 13204 is as small as possible, but cannot be too small, so that the operation of the second spool 133 is blocked and the function of the flow restriction valve fails.

The flow limiting valve assembly 13 is used in a high-pressure common rail system of a low-speed diesel engine, and the combustion medium of the flow limiting valve assembly is poor fuel oil. In order to ensure the service life and the functional reliability of the flow restriction valve, the second valve core 133 is made of high-speed tool steel material, DLC is plated on the matching sections (the first outer circle 13301, the second outer circle 13303, the third sealing conical surface 13305 and the fourth sealing conical surface 13306) of the second valve body 132, the second valve body 132 is made of high-strength structural steel, and the flow restriction valve is ensured to be resistant to high temperature and corrosion by adopting the material and a heat treatment method.

The second valve spool 133 is pushed forward by the oil inlet pressure of the fuel and the elastic force of the second pressure regulating spring 135, and when the second valve spool 133 is pushed forward, the second valve spool 133 seals the fourth hole 13207 serving as an oil outlet to block the fuel from entering; the fuel oil is cut off, the over-spraying of the electric control fuel injector 15 or the leakage of a high-pressure fuel pipe are avoided, the diesel engine or personnel are prevented from being injured, and the environment pollution is also prevented.