阅读说明：本技术 一种高效多级制动机构 (High-efficient multistage arrestment mechanism ) 是由 崔靖晨 隆武强 孟相宇 礼博 田华 王阳 于 2020-09-01 设计创作，主要内容包括：本发明提供一种高效多级制动机构。本发明包括外壳、设置在外壳上且相对外壳固定或往复运动的柱塞套、设置在柱塞套上且相对柱塞套往复运动的柱塞、液压控制单元。柱塞套侧壁上设置至少一个第一通道,第一通道内设置有相对第一通道往复运动的锁定体,液压控制单元与柱塞与柱塞套之间形成的第二油腔相连,也与柱塞套、外壳和锁定体之间形成的第一油腔相连。通过调节各油腔和低压源、高压源的连通关系,实现了失效模式、第一有效模式和第二有效模式。本机构尺寸紧凑,可靠性高,能够通过取代原配气机构的某个零部件,满足发动机紧凑型安装和尽可能采用原配气机构零部件等要求,实现发动机多级制动和产品极低成本的升级换代,非常有利于产品推广应用。(The invention provides a high-efficiency multistage braking mechanism. The invention comprises a shell, a plunger sleeve which is arranged on the shell and fixed or reciprocates relative to the shell, a plunger which is arranged on the plunger sleeve and reciprocates relative to the plunger sleeve, and a hydraulic control unit. The side wall of the plunger sleeve is provided with at least one first channel, a locking body which reciprocates relative to the first channel is arranged in the first channel, and the hydraulic control unit is connected with a second oil cavity formed between the plunger and the plunger sleeve and also connected with a first oil cavity formed among the plunger sleeve, the shell and the locking body. By adjusting the communication relation among the oil cavities, the low-pressure source and the high-pressure source, a failure mode, a first effective mode and a second effective mode are realized. The mechanism has compact size and high reliability, can meet the requirements of compact installation of the engine and adoption of parts of the original valve actuating mechanism as far as possible by replacing a certain part of the original valve actuating mechanism, realizes the multi-stage braking of the engine and the upgrade and update of the product with extremely low cost, and is very favorable for the popularization and application of the product.)

1. A high-efficiency multistage braking mechanism is characterized by comprising a shell (2), a plunger sleeve (4) which is arranged on the shell (2) and fixed or reciprocates relative to the shell (2), a plunger (5) which is arranged on the plunger sleeve (4) and reciprocates relative to the plunger sleeve (4), and a hydraulic control unit (12);

when the plunger sleeve (4) is fixed relative to the shell (2), a second oil cavity (Q2) is formed among the plunger (5), the plunger sleeve (4) and the shell (2) or a block (16) fixed relative to the plunger sleeve (4); when the plunger sleeve (4) reciprocates relative to the shell (2), a second oil cavity (Q2) is formed between the plunger (5) and the plunger sleeve (4);

the hydraulic control unit (12) is connected with the second oil chamber (Q2) through a second oil path (A2) and a hydraulic linkage valve, when the hydraulic control unit (12) connects the second oil path (A2) with a high pressure source (HP), hydraulic oil enters the second oil chamber (Q2) only through a check valve arranged in the hydraulic linkage valve, and when the hydraulic control unit (12) connects the second oil path (A2) with a low pressure source (LP), the hydraulic oil in the second oil chamber (Q2) enters the second oil path (A2) through the hydraulic linkage valve or directly enters the low pressure source (LP); or the hydraulic control unit (12) is connected with the second oil chamber (Q2) through two oil paths, one path is connected with the second oil chamber (Q2) only by entering and exiting through a fourth oil path (A4) and a one-way valve (13), and the other path is connected with the second oil chamber (Q2) through a fifth oil path (A5);

a limiting device for limiting the maximum volume of the second oil chamber (Q2) is arranged between the plunger sleeve (4) and the plunger (5); at least one first channel (7) is arranged on the side wall of the plunger sleeve (4), and a locking body (6) which reciprocates relative to the first channel (7) is arranged in the first channel (7); a first oil cavity (Q1) is formed among the plunger sleeve (4), the shell (2) and the locking body (6); the hydraulic control unit (12) is connected with a first oil chamber (Q1) through a first oil path (A1); the plunger (5) is provided with a locking body resetting mechanism;

in the first active mode, the first oil passage (a1) is connected to the high pressure source (HP);

the second oil passage (a2) is connected to the high pressure source (HP), or the fourth oil passage (a4) is connected to the high pressure source (HP) and the fifth oil passage (a5) is blocked;

in the failure mode, the first oil passage (A1) is connected with a low pressure source (LP);

the second oil passage (a2) is connected to the low pressure source (LP), or the fourth oil passage (a4) is blocked or connected to the low pressure source (LP) and the fifth oil passage (a5) is connected to the low pressure source (LP).

2. A high-efficiency multistage brake mechanism according to claim 1, characterized in that in the second effective mode, the first oil passage (a1) is connected to a low pressure source (LP);

the second oil passage (a2) is connected to the high pressure source (HP), or the fourth oil passage (a4) is connected to the high pressure source (HP) and the fifth oil passage (a5) is blocked.

3. The high efficiency multi-stage brake mechanism of claim 1, wherein the lockout body reset mechanism has three reset schemes;

when a first resetting scheme is adopted, at least one second channel (10) is arranged on the side wall of the plunger (5), a spring (8) and a spring seat (9) are arranged in the second channel (10), and a guide mechanism is arranged between the plunger (5) and the plunger sleeve (4); when the volume of the second oil chamber (Q2) is maximum, the locking body (6) reaches an axial position at which the locking body (6) can protrude into the second passage (10) or into a circumferential groove provided on a side wall of the plunger (5) and connected to the second passage (10), and the locking body (6) is in contact with the spring seat (9);

when a second resetting scheme is adopted, at least one circumferential ring groove is formed in the side wall of the plunger (5), and a spring piece is arranged in the circumferential ring groove; when the volume of the second oil chamber (Q2) is maximum, the locking body (6) reaches an axial position at which the locking body (6) can extend into the circumferential ring groove, and the locking body (6) is in contact with the spring piece;

when a third resetting scheme is adopted, a channel and/or a circumferential groove are/is formed in the side wall of the plunger (5), a third oil cavity (Q3) is formed among the plunger (5), the plunger sleeve (4) and the locking body (6), and the hydraulic control unit (12) is connected with the third oil cavity (Q3) through a third oil path (A3); when the volume of the second oil chamber (Q2) is maximum, the locking body (6) reaches an axial position at which the locking body (6) can extend into the channel or the circumferential groove; when the hydraulic control unit (12) connects the first oil passage (A1) to the high pressure source (HP), the third oil passage (A3) is connected to the low pressure source (LP); the hydraulic control unit (12) connects the third oil passage (A3) to the high pressure source (HP) while connecting the first oil passage (A1) to the low pressure source (LP).

4. A high efficiency multi-stage brake mechanism as claimed in claim 1 wherein said hydraulic linkage valve has three options:

the first hydraulic linkage valve (11) comprises a one-way valve and a two-position three-way linkage valve with a port P, a port T and a port A, a second oil way (A2) is connected with the port P through the one-way valve, the port A is connected with a second oil cavity (Q2), and the port T is connected with a second oil way (A2) or a low-pressure source (LP); the second oil path (A2) is connected to a spool drive chamber of the two-position three-way valve, when the second oil path (A2) is connected with a high pressure source (HP), a port P is connected with a port A, and a port T is cut off; when the second oil passage (A2) is connected with the low pressure source (LP), the T port is connected with the A port, and the P port is cut off;

the second hydraulic linkage valve (17) comprises a one-way valve and a two-position two-way linkage valve with a T port and an A port, a second oil way (A2) is simultaneously connected with the A port and a second oil cavity (Q2) through the one-way valve, and the T port is connected with a second oil way (A2) or a low-pressure source (LP); the second oil path (A2) is connected to a valve core driving cavity of the two-position two-way valve, and when the second oil path (A2) is connected with a high pressure source (HP), the T port is disconnected with the A port; when the second oil passage (a2) is connected to the low pressure source (LP), the T port is connected to the a port;

the third hydraulic linkage valve (18) comprises a one-way valve and a linkage piston rod (19), and the second oil path (A2) is connected with the second oil chamber (Q2) through the one-way valve; a second oil passage (A2) connected to the drive chamber of the interlocking piston rod (19), the interlocking piston rod (19) not contacting the check valve spool when the second oil passage (A2) is connected to the high pressure source (HP); when the second oil passage (A2) is connected to the low pressure source (LP), the interlocking piston rod (19) pushes the check valve spool to be in an open state.

5. The efficient multi-stage brake mechanism according to claim 2, wherein the hydraulic control unit is at least one hydraulic valve, the port P of the hydraulic valve is connected with a high-pressure source, and the port T of the hydraulic valve is connected with the high-pressure source;

the first scheme is as follows: a two-position three-way valve is adopted, wherein an A port of the two-position three-way valve is connected with a first oil path (A1) and a second oil path (A2), when a valve core is at a first position, the A port is connected with a T port, and a P port is cut off; when the valve core is at the second position, the port A is connected with the port P, and the port T is cut off;

the second scheme is as follows: a two-position four-way valve is adopted, wherein an A port of the two-position four-way valve is connected with a first oil way (A1) and a second oil way (A2), a B port of the two-position four-way valve is connected with a third oil way (A3), when a valve core is positioned at a first position, the A port is connected with a T port, and the B port is connected with a P port; when the valve core is at the second position, the port A is connected with the port P, and the port B is connected with the port T; the third scheme is as follows: a two-position four-way valve is adopted, wherein an A port of the two-position four-way valve is connected with a first oil way (A1) and a fourth oil way (A4), a B port of the two-position four-way valve is connected with a fifth oil way (A5), when a valve core is positioned at a first position, the A port and the B port are both connected with a T port, and a P port is cut off; when the valve core is at the second position, the port A is connected with the port P, and the port B and the port T are both cut off;

the fourth scheme is as follows: a two-position five-way valve is adopted, wherein a port A is connected with a first oil way (A1) and a fourth oil way (A4), a port B is connected with a fifth oil way (A5), a port C is connected with a third oil way (A3), when a valve core is at a first position, the port A and the port B are both connected with a port T, and the port C is connected with a port P; when the valve core is at the second position, the port A is connected with the port P, the port B is cut off, and the port C is connected with the port T;

when any scheme of the first scheme, the fourth scheme and the fourth scheme is adopted, the valve core is switched to the first position when the engine needs to run in a failure mode; when the engine needs to operate in a first effective mode, the valve core is switched to a second position;

the fifth scheme is as follows: a three-position four-way valve is adopted, wherein an A port is connected with a first oil way (A1), a B port is connected with a second oil way (A2), when a valve core is positioned at a first position, the A port and the B port are both connected with a T port, and a P port is cut off; when the valve core is at the second position, the port B is connected with the port P, and the port A is connected with the port T; when the valve core is at the third position, the port A and the port B are connected with the port P, and the port T is cut off;

a sixth aspect: a three-position five-way valve is adopted, wherein a port A is connected with a first oil way (A1), a port B is connected with a fourth oil way (A4), a port C is connected with a fifth oil way (A5), when the valve core is at a first position, the port A and the port C are both connected with a port T, the port P is cut off, and the port B is connected with the port T or the port B is cut off; when the valve core is at the second position, the port B is connected with the port P, the port C is cut off, and the port A is connected with the port T; when the valve core is at the third position, the port A and the port B are connected with the port P, and the port C and the port T are cut off;

a seventh aspect: a three-position five-way valve is adopted, wherein a port A is connected with a first oil way (A1), a port B is connected with a second oil way (A2), a port C is connected with a third oil way (A3), when the valve core is at a first position, the port A and the port B are both connected with a port T, and the port C is connected with a port P; when the valve core is at the second position, the port B and the port C are both connected with the port P, and the port A is connected with the port T; when the valve core is at the third position, the port A and the port B are both connected with the port P, and the port C is connected with the port T;

an eighth aspect: a three-position six-way valve is adopted, wherein a port A is connected with a first oil way (A1), a port B is connected with a fourth oil way (A4), a port C is connected with a fifth oil way (A5), a port D is connected with a third oil way (A3), when a valve core is at a first position, the port A and the port C are both connected with a port T, the port B is cut off or connected with the port T, and the port D is connected with a port P; when the valve core is at the second position, the port B and the port D are both connected with the port P, the port C is cut off, and the port A is connected with the port T; when the valve core is at the third position, the port A and the port B are both connected with the port P, the port C is cut off, and the port D is connected with the port T;

when any scheme of the fifth scheme to the eighth scheme is adopted, the valve core is switched to the first position when the engine needs to run in a failure mode; when the engine needs to operate in a second effective mode, the valve core is switched to a second position; when the engine needs to operate in the first effective mode, the valve core is switched to the third position;

the ninth proposal: two-position three-way valves are adopted, the port A of the first two-position three-way valve is connected with a first oil way (A1), when the valve core is at the first position, the port A is connected with the port T, the port P is cut off, when the valve core is at the second position, the port A is connected with the port P, and the port T is cut off; the port A of the second two-position three-way valve is connected with a second oil way (A2), when the valve core is at the first position, the port A is connected with the port T, the port P is cut off, when the valve core is at the second position, the port A is connected with the port P, and the port T is cut off; when the engine needs to operate in a failure mode, the valve cores of the first two-position three-way valve and the second two-position three-way valve are switched to a first position; when the engine needs to operate in a second effective mode, the first two-position three-way valve is switched to a first position, and the valve core of the second two-position three-way valve is switched to a second position; when the engine needs to operate in a first effective mode, the valve cores of the first two-position three-way valve and the second two-position three-way valve are switched to a second position;

the tenth scheme: a two-position three-way valve and a two-position four-way valve are adopted, an A port of the two-position three-way valve is connected with a second oil way (A2), when the valve core is at a first position, the A port is connected with a T port, the P port is cut off, when the valve core is at a second position, the A port is connected with the P port, and the T port is cut off; an A port of the two-position four-way valve is connected with a first oil way (A1), a B port of the two-position four-way valve is connected with a third oil way (A3), when the valve core is at a first position, the A port is connected with a T port, and the B port is connected with a P port; when the valve core is at the second position, the port A is connected with the port P, and the port B is connected with the port T; when the engine needs to operate in a failure mode, valve cores of the two-position three-way valve and the two-position four-way valve are switched to a first position; when the engine needs to operate in a second effective mode, the two-position three-way valve is switched to a second position, and the valve core of the two-position four-way valve is switched to a first position; when the engine needs to operate in a first effective mode, valve cores of the two-position three-way valve and the two-position four-way valve are switched to a second position;

an eleventh aspect: a two-position three-way valve and a two-position four-way valve are adopted, an A port of the two-position three-way valve is connected with a first oil way (A1), when the valve core is at a first position, the A port is connected with a T port, the P port is cut off, when the valve core is at a second position, the A port is connected with the P port, and the T port is cut off; an A port of the two-position four-way valve is connected with a fourth oil way (A4), a B port of the two-position four-way valve is connected with a fifth oil way (A5), when the valve core is at a first position, the A port is cut off or connected with a T port, the B port is connected with the T port, and the P port is cut off; when the valve core is at the second position, the port A is connected with the port P, and the port B and the port T are both cut off; when the engine needs to operate in a failure mode, valve cores of the two-position three-way valve and the two-position four-way valve are switched to a first position; when the engine needs to operate in a second effective mode, the two-position three-way valve is switched to a first position, and the valve core of the two-position four-way valve is switched to a second position; when the engine needs to operate in a first effective mode, valve cores of the two-position three-way valve and the two-position four-way valve are switched to a second position;

the twelfth aspect: two-position four-way valves are adopted, an A port of the first two-position four-way valve is connected with a first oil way, a B port of the first two-position four-way valve is connected with a third oil way, when the valve core is at a first position, the A port is connected with a T port, the B port is connected with a P port, when the valve core is at a second position, the A port is connected with the P port, and the B port is connected with the T port; the port A of the second two-position four-way valve is connected with the fourth oil way, the port B is connected with the fifth oil way, when the valve core is at the first position, the port A is cut off or connected with the port T, the port B is connected with the port T, and the port P is cut off; when the valve core is at the second position, the port A is connected with the port P, and the port B and the port T are both cut off; when the engine needs to operate in a failure mode, the valve cores of the first two-position four-way valve and the second two-position four-way valve are switched to a first position; when the engine needs to operate in a second effective mode, the first two-position four-way valve is switched to a first position, and the valve core of the second two-position four-way valve is switched to a second position; and when the engine needs to operate in the first effective mode, the valve cores of the first two-position four-way valve and the second two-position four-way valve are switched to the second position.

6. A high-efficiency multi-stage brake mechanism according to claim 3, wherein the guide mechanism arranged between the plunger and the plunger sleeve comprises a vertical guide groove arranged on the outer wall surface of the plunger or a vertical guide groove arranged on the inner wall surface of the plunger sleeve; when the outer wall surface of the plunger is provided with the vertical guide groove, the end part of the corresponding locking body or the guide body additionally arranged on the plunger sleeve always extends into the vertical guide groove; when the vertical guide groove is formed in the inner wall surface of the plunger sleeve, the end part of the corresponding spring seat or the guide body additionally arranged on the plunger always extends into the vertical guide groove.

7. The efficient multistage braking mechanism according to claim 1 or 6, wherein when the rotation motion of the plunger sleeve relative to the shell needs to be limited, a second guiding mechanism is arranged between the plunger sleeve and the shell, the second guiding mechanism comprises a guiding vertical groove arranged on the inner wall surface of the shell or a guiding vertical groove arranged on the outer wall surface of the plunger sleeve, and when the guiding vertical groove is arranged on the inner wall surface of the shell, the end part of a corresponding locking body or a guiding body additionally arranged on the plunger sleeve always extends into the guiding vertical groove; when the outer wall surface of the plunger sleeve is provided with the vertical guide groove, the guide body additionally arranged on the shell always extends into the vertical guide groove; the outer wall surface of the plunger and the inner wall surface of the shell are provided with vertical guide grooves, and two corresponding end parts of the locking body or the guide body additionally arranged on the plunger sleeve always extend into the vertical guide grooves, so that the guide among the shell, the plunger sleeve and the plunger is realized.

8. A high-efficiency multistage braking mechanism as claimed in claim 7, characterized in that the side wall surface of the locking body contacting with the circumferential groove is processed into an arc surface or a plane with a preset curvature radius, and the locking body is provided with an anti-rotation mechanism, which comprises a collar arranged in a slot on the locking body or a matching of the collar and the vertical guide groove.

Technical Field

The invention relates to the technical field of variable valve actuating mechanisms of engines, in particular to a high-efficiency multistage braking mechanism.

Background

With the development of the energy-saving and emission-reducing technology of the whole vehicle, the braking capability of the vehicle is reduced; as the load capacity, speed, etc. of the entire vehicle increase, the demand for braking power increases, which requires the braking system to provide greater braking power. The main braking system and the retarder assembled on the vehicle transmission system have the problems that the heat fading is easy to occur after long-time work, so that the braking power is rapidly reduced, even the braking fails, the service life of the braking system is greatly reduced, and the like. Under the background, engine braking without heat fading problem becomes one of the key technologies of the whole vehicle braking.

Improving engine braking power and variable valve train reliability are major challenges in engine braking. In particular, engine braking is required not only for large commercial vehicles equipped with large displacement engines, but also increasingly for small and medium commercial vehicles equipped with small displacement engines and large hybrid commercial vehicles. At the same rotating speed, the engine braking power is greatly reduced along with the reduction of the engine displacement, so that the further improvement of the decompression braking performance of the engine, particularly the development of two-stroke braking, becomes necessary.

Both four-stroke compression-release braking and two-stroke braking (hereinafter collectively referred to as braking, unless otherwise specified) rely heavily on the development of variable valve trains, which must satisfy the following requirements simultaneously:

(1) the engine can be arranged in a given external dimension of the engine (namely, the length, the width and the height of the engine are not increased), the modification on the engine is reduced as much as possible, and the parts and the like of the original engine valve mechanism are adopted as much as possible, so that the low-cost product upgrading is realized.

(2) Reliable operation and fast switching can be achieved within the range of rotation speeds required by the engine.

(3) The valve lift profile required for optimum engine performance can be provided.

(4) The number of the braking grades is increased, and the range of the braking working conditions is covered as much as possible.

On the basis that the four-stroke decompression braking does not need to change the original engine valve actuating mechanism, a braking transmission chain is additionally arranged for a braking exhaust valve; the two-stroke brake needs to be provided with an air inlet/exhaust driving transmission chain and an air inlet/exhaust braking transmission chain, and the switching of the running mode of the engine is realized by controlling the working states of the driving mechanism and the braking mechanism. Wherein the brake transmission chain is a transmission chain from a brake cam to a brake valve, which comprises a brake mechanism, and the working state of the brake mechanism determines the working state of the transmission chain; the drive transmission chain is a transmission chain from the drive cam to the drive valve including a drive mechanism, wherein the operating state of the drive mechanism determines the operating state of the transmission chain.

The inventor finds out through a great deal of research that: compared with the traditional variable valve actuating mechanism, the development difficulty of the variable valve actuating mechanism required by engine braking is higher; the difficulty lies mainly in the development of braking mechanisms, in particular on the exhaust side, due to the following:

(1) because the maximum braking rotating speed of the engine is far greater than the rated rotating speed, particularly a small-displacement engine, the overhigh braking rotating speed can cause the pure hydraulic braking mechanism to be incapable of working normally due to pump rise and the like.

(2) In the braking mode, the pressure in the cylinder near the compression top dead center or each top dead center is very high and the pressure fluctuation is severe, and the braking mechanism needs to overcome the very large gas force changing at high frequency to open the valve; meanwhile, the pressure in the cylinder increases along with the increase of the rotating speed, the braking rotating speed of the engine is extremely high, the stress condition of a braking mechanism is very severe, and the failure rate of related parts is very high, so that the reliability design is an industrial problem.

(3) The two-stroke exhaust brake cam is provided with a plurality of bulges, the base circle sections of the two-stroke exhaust brake cam are dispersed, and the phase area of the largest base circle section is much shorter than that of the traditional variable valve actuating mechanism; in addition, the engine braking speed is very high, so the braking mechanism needs to have a very high switching response speed to realize that the braking mode can be switched to the braking mode quickly and smoothly in more rotation speed ranges to improve the engine braking duty ratio, further reduce the use frequency and strength of the main braking system, improve the service life of the main braking system, and reduce the dust pollution of the friction type braking system.

(4) In order to exert the maximum effect of engine braking under different load capacities, slopes, slope lengths and the like, it is necessary to increase the maximum braking power output as much as possible and to realize multistage braking.

The inventor carries out a great deal of research and comparative analysis on the existing brake mechanism and the application effect of the existing brake mechanism on an engine, and finds out the advantages of the existing brake mechanism and the problems to be solved:

(1) pure hydraulic braking mechanism: adopt principal and subordinate piston structure, the advantage is: (a) the maximum cylinder pressure is lower, the stress of the brake mechanism is smaller, and the brake mechanism has a hydraulic buffer function, so that the reliability of the brake mechanism is high. (b) The sectional switching does not influence the structural reliability of the braking mechanism. There are problems in that: (a) the pressure in the cylinder near the top dead center is very high, so that serious lift loss occurs in a valve lift curve generated by the mechanism, namely the valve cannot keep a large lift, and the braking power is greatly reduced and the maximum cylinder pressure in a braking high-speed area is rapidly increased. (b) The pump-up phenomenon occurs at high speed, which causes serious accidents such as overlarge pressure of a hydraulic oil cavity, collision of a valve and a piston and the like. (c) The operation rotating speed range is limited by the collision of the valve and the piston, the pumping effect and the like, and the device can only work in a limited rotating speed range. (d) The lift of the exhaust brake cam is limited near the top dead center, and a larger lobe cannot be used, and thus higher brake power output cannot be obtained.

(2) Pure mechanical braking mechanism: the mechanical locking structure is adopted, the valve lift is not influenced by the pressure in the cylinder, and the braking power is higher than that of a pure hydraulic braking mechanism. There are problems in that: (a) the maximum cylinder pressure is high, and the stress of the brake mechanism is large. (b) The impact force applied to the braking mechanism is very large, especially the pressure in the engine cylinder changes violently, and related parts are very easy to damage. (c) The switching can only be carried out in the base circle section of the braking cam, and the difficulty of completing the switching at one time is increased along with the increase of the rotating speed, particularly during two-stroke braking; the stepwise switching will result in a further substantial reduction in the reliability of the purely mechanical brake mechanism, since when the locking pin is in the intermediate state of switching, the contact surface between the locking pin and the body to be locked is smaller than when fully switched, in which case opening and closing the valve will result in a substantial increase in the contact stress between the locking pin and the body to be locked, in particular in the vicinity of top dead centre. Both of these aspects result in a high failure rate for purely mechanical braking mechanisms.

(3) A composite brake mechanism: the inner plunger is capable of sliding up and down within a vertical bore in the drive piston as disclosed in the integrated lost motion rocker brake system with automatic reset, application No. 201390000921.7. The inner plunger has an annular groove structure or an inclined surface structure shaped to receive one or more wedges, rollers or spherical locking elements. The drive piston assembly outer wall also has one or more slots capable of receiving one or more of the above-described locking elements. When braking is needed, the high-pressure hydraulic oil drives the driving piston and the internal plunger to overcome the pre-tightening force of the driving piston spring and the internal plunger spring, so that the driving piston and the internal plunger are separated; when the inner plunger is fully displaced, the inner plunger drives the locking member into one or more grooves in the wall of the drive piston assembly, thereby mechanically locking the brake piston in the rocker arm. When the brake is not needed, the hydraulic pressure is removed, the inner plunger piston is pushed by the inner plunger piston spring to move, the locking element returns to the annular groove structure or the inclined surface structure of the inner plunger piston, the locking of the inner plunger piston and the driving piston is realized, and the inner plunger piston and the driving piston are reset by the driving piston spring. The composite brake mechanism has the advantages of a pure hydraulic brake mechanism and a pure mechanical brake mechanism at the same time: (a) the valve lift is not influenced by the pressure in the cylinder, and the braking power is higher than that of a pure hydraulic braking mechanism. (b) The sectional switching does not influence the structural reliability of the braking mechanism. However, the following problems remain to be improved: (a) it can be seen from the above structure and switching process that the locking element is ensured to be able to smoothly move back and forth between the ring groove of the inner plunger and the groove of the wall of the driving piston assembly, i.e. when the switching is smoothly required to contact the ring groove of the inner plunger, the acting line of the resultant force is outside the friction angle, otherwise, self-locking occurs; similarly, when the lock member is in contact with the groove in the wall of the driving piston assembly, the acting line of the resultant force is required to be beyond the friction angle, otherwise self-locking occurs, so that the lock member is required to be in a specially designed shape such as a wedge, a roller or a sphere, and the inner plunger ring groove and the groove in the wall of the driving piston assembly are also required to be specially designed; the existing composite brake mechanism only adopts hydraulic transmission in the switching process, and adopts mechanical transmission after the switching is finished, so that the impact of gas force directly acts on the brake mechanism; the anti-self-locking design results in that the resultant force of the acting forces between the locking element and the inner plunger ring groove and the resultant force of the acting forces between the locking element and the groove of the wall of the driving piston assembly are much larger than the force of the valve on the driving piston, and the corresponding contact stress is greatly increased; particularly, when the brake mechanism is applied to the exhaust side, reliability is difficult to guarantee, and after long-time operation, deformation is easy to occur between the locking element and the groove on the wall of the driving piston assembly, which further causes the actual shapes of the locking element and the groove on the wall of the driving piston assembly to gradually deviate from the designed shapes and to be locked, and finally causes serious faults such as the engine being incapable of working normally. (b) In the case of the locking element, both ends of the locking element, whether in the annular groove of the internal plunger spring or in the groove of the wall of the drive piston assembly, need to adopt a special design that allows smooth switching, so that the locking element cannot be in full-length contact with the duct in the drive piston, and the smaller contact surface further causes a very large contact stress, which is very disadvantageous to the reliability and the service life of the locking element and the drive piston. (c) In order to ensure the reliability of the mechanism, the size of the mechanism is greatly increased, which makes it difficult to meet the engine installation requirements.

In view of the above, the inventors propose to develop a methodAt the same time satisfyThe operating and switching speed ranges are not restricted, and the highest possible braking is achievedThe brake mechanism which can provide more brake power output grades and meet the requirements of compact installation of an engine and the like by adopting the parts of the original valve mechanism as far as possible is a research target in the field of engine braking and variable valve mechanisms.

Disclosure of Invention

In view of the above-mentioned technical problems, an efficient multi-stage brake mechanism is provided. The technical means adopted by the invention are as follows:

a high-efficiency multistage braking mechanism comprises a shell, a plunger sleeve, a plunger and a hydraulic control unit, wherein the plunger sleeve is arranged on the shell and fixed or reciprocates relative to the shell; when the plunger sleeve is fixed relative to the shell, a second oil cavity is formed among the plunger, the plunger sleeve and the shell or a block fixed relative to the plunger sleeve; when the plunger sleeve reciprocates relative to the shell, a second oil cavity is formed between the plunger and the plunger sleeve; the hydraulic control unit is connected with the second oil cavity through a second oil way and a hydraulic linkage valve, when the hydraulic control unit connects the second oil way with a high-pressure source, hydraulic oil only enters the second oil cavity but cannot enter the second oil cavity through a one-way valve arranged in the hydraulic linkage valve, and when the hydraulic control unit connects the second oil way with a low-pressure source, the hydraulic oil in the second oil cavity enters the second oil way through the hydraulic linkage valve or directly enters the low-pressure source; or the hydraulic control unit is connected with the second oil cavity through two oil ways, one way is connected with the second oil cavity only through a fourth oil way and a one-way valve and only can enter and exit, and the other way is connected with the second oil cavity through a fifth oil way; a limiting device for limiting the maximum volume of the second oil cavity is arranged between the plunger sleeve and the plunger; at least one first channel is arranged on the side wall of the plunger sleeve, and a locking body which reciprocates relative to the first channel is arranged in the first channel; a first oil cavity is formed among the plunger sleeve, the shell and the locking body; the hydraulic control unit is connected with the first oil cavity through a first oil way; and a locking body resetting mechanism is arranged on the plunger. In the first effective mode, the first oil way is connected with a high-pressure source; the second oil passage is connected to the high pressure source, or the fourth oil passage is connected to the high pressure source and the fifth oil passage is blocked. In a failure mode, the first oil way is connected with a low-pressure source; the second oil passage is connected to a low pressure source, or the fourth oil passage is cut off or connected to a low pressure source and the fifth oil passage is connected to a low pressure.

Further, in the second effective mode, the first oil way is connected with a low-pressure source; the second oil passage is connected to the high pressure source, or the fourth oil passage is connected to the high pressure source and the fifth oil passage is blocked.

Further, the locking body reset mechanism has three reset schemes. When the first resetting scheme is adopted, at least one second channel is arranged on the side wall of the plunger, a spring and a spring seat are arranged in the second channel, and a guide mechanism is arranged between the plunger and the plunger sleeve; when the second oil chamber volume is at a maximum, the lock body reaches an axial position at which the lock body can protrude into the second passage or into a circumferential groove provided on the plunger side wall and connected to the second passage, and the lock body is in contact with the spring seat. When a second resetting scheme is adopted, at least one circumferential ring groove is formed in the side wall of the plunger, and a spring piece is arranged in the circumferential ring groove; when the second oil chamber volume is maximum, the lock body reaches an axial position where the lock body can protrude into the circumferential ring groove, and the lock body is in contact with the spring piece. When a third resetting scheme is adopted, a channel and/or a circumferential groove are/is formed in the side wall of the plunger, a third oil cavity is formed among the plunger, the plunger sleeve and the locking body, and the hydraulic control unit is connected with the third oil cavity through a third oil way; when the volume of the second oil chamber is maximum, the locking body reaches an axial position at which the locking body can extend into the channel or the circumferential groove; when the hydraulic control unit connects the first oil way with a high pressure source, the third oil way is connected with a low pressure source; when the hydraulic control unit connects the first oil passage with the low pressure source, the third oil passage is connected with the high pressure source.

Furthermore, the hydraulic linkage valve has three schemes. The first hydraulic linkage valve comprises a one-way valve and a two-position three-way linkage valve with a port P, a port T and a port A, the second oil way is connected with the port P through the one-way valve, the port A is connected with the second oil cavity, and the port T is connected with the second oil way or connected with a low-pressure source; the second oil way is connected to the valve core driving cavity of the two-position three-way valve, when the second oil way is connected with a high-pressure source, the port P is connected with the port A, and the port T is cut off; when the second oil passage is connected to the low pressure source, the port T is connected to the port A, and the port P is cut off. The second hydraulic linkage valve comprises a one-way valve and a two-position two-way linkage valve with a T port and an A port, the second oil way is simultaneously connected with the A port and the second oil cavity through the one-way valve, and the T port is connected with the second oil way or connected with a low-pressure source; the second oil way is connected to the valve core driving cavity of the two-position two-way valve, and when the second oil way is connected with a high-pressure source, the T port is disconnected with the A port; when the second oil passage is connected to the low pressure source, the port T is connected to the port a. The third hydraulic linkage valve comprises a one-way valve and a linkage piston rod, and the second oil way is connected with the second oil cavity through the one-way valve; the second oil path is connected to the drive cavity of the linkage piston rod, and when the second oil path is connected with a high-pressure source, the linkage piston rod is not contacted with the valve core of the one-way valve; when the second oil way is connected with a low-pressure source, the linkage piston rod pushes the valve core of the one-way valve to be in an opening state.

Furthermore, the hydraulic control unit adopts at least one hydraulic valve, a port P of the hydraulic valve is connected with a high-pressure source, and a port T of the hydraulic valve is connected with the high-pressure source; the control of the communication relation among the oil cavities, the high-pressure source and the low-pressure source can be realized by adopting various schemes, and further, the switching of different modes of the mechanism is realized.

It should be noted that, unless otherwise specified, the reciprocating motion may or may not be relative rotation while reciprocating motion is performed. For the need to limit the rotatory movement of the plunger bushing relative to outer casing, for example when setting up the roller driven by cam on the plunger bushing, set up the guiding mechanism between outer casing and the plunger bushing; the relative rotational movement between the plunger and the plunger sleeve needs to be limited, for example, when the locking body adopts a scheme of resetting by a spring and a spring seat, a guide mechanism is additionally arranged between the plunger and the plunger sleeve. Various guiding schemes can be adopted between the plunger and the plunger sleeve and between the shell and the plunger sleeve, for example, a guiding vertical groove is arranged on the outer wall surface of the plunger, and the end part of a corresponding locking body or a guiding body additionally arranged on the plunger sleeve always extends into the guiding vertical groove; or a vertical guide groove is formed in the inner wall surface of the plunger sleeve, and the end part of the corresponding spring seat or a guide body additionally arranged on the plunger always extends into the vertical guide groove, so that the guide between the plunger and the plunger sleeve can be realized. A guide vertical groove is arranged on the inner wall surface of the shell, and the end part of the corresponding locking body or the guide body additionally arranged on the plunger sleeve always extends into the guide vertical groove; or the outer wall surface of the plunger sleeve is provided with a vertical guide groove, and the guide body additionally arranged on the shell always extends into the vertical guide groove, so that the guide between the shell and the plunger sleeve can be realized. The outer wall surface of the plunger and the inner wall surface of the shell are provided with vertical guide grooves, and two end parts of the corresponding locking bodies or the guide bodies additionally arranged on the plunger sleeve always extend into the vertical guide grooves, so that the guide among the shell, the plunger sleeve and the plunger can be realized. In addition, the guide vertical grooves can be replaced by guide surfaces, and the guide can be realized through paired guide surfaces or the combination of the guide surfaces and the guide bodies.

When the locking body extends into the circumferential groove to realize locking, in order to reduce contact stress, the side wall surface of the locking body contacting with the circumferential groove can be processed into a cambered surface or a plane with a large curvature radius. At this time, an anti-autorotation mechanism can be additionally arranged on the locking body so as to be locked smoothly. For example, the locking body can be prevented from rotating by slotting the locking body and installing the retainer ring in the locking body slot; if the plunger and/or the shell is/are provided with the vertical guide groove, the side wall surface which is vertical to the cambered surface or the plane of the locking body and is used for contacting with the circumferential groove is processed into a cambered surface or a plane with large curvature radius matched with the vertical guide groove, and the self-rotation of the locking body is prevented by utilizing the cambered surface or the plane and the vertical guide groove

There are many methods for limiting the maximum volume of the second oil chamber, for example, a shoulder or a collar is provided on the plunger sleeve, and in addition, the limiting function can be realized by using the guide body and the guide vertical groove.

On the scheme that the plunger sleeve is fixed in the shell, when the plunger sleeve is provided with a shoulder to limit the maximum volume of the second oil cavity, in order to ensure that hydraulic oil in the second oil cavity cannot cause the plunger sleeve to move relative to the shell, the plunger sleeve needs to be limited relative to the shell, for example, the plunger sleeve is mounted on the shell in a threaded or interference fit mode, or the plunger sleeve is limited by a clamping ring or the like, or a plug block is fixedly mounted on the plunger sleeve in various modes.

The mechanism provides a high-efficiency multistage braking mechanism, meets various design requirements of a variable valve actuating mechanism, and has the following advantages:

(a) the mechanism can replace a certain part of the original valve actuating mechanism, meet the requirements of compact installation of an engine, adoption of the parts of the original valve actuating mechanism as far as possible and the like, realize the upgrade and update of the product with extremely low cost, and is very favorable for popularization and application of the product. For example, when the shell and the plunger sleeve move relatively, the mechanism can be used as a tappet with multi-stage variable functions, a valve bridge or the like, and when the shell and the plunger sleeve are relatively fixed, the mechanism can be used as a fixed fulcrum or the like of a rocker arm with multi-stage variable functions, or a moving part such as the rocker arm.

(b) The mechanism not only has the advantages of the existing composite brake mechanism, but also has more compact size and greatly improved reliability compared with the existing composite brake mechanism. The reciprocating motion of the locking body of the mechanism is realized by controlling the pressure of the first oil cavity, the position adjustment of the locking body does not have the problems of self locking or blocking and the like, the part of the locking body, which is in contact with the shell, and the part of the locking body, which is in contact with the plunger, do not need to be specially designed, the stress of the locking body and the part, which is in contact with the locking body, cannot be amplified, the locking body can be always in contact with the first channel of the plunger sleeve in the whole length, and the two aspects of the reciprocating motion of the locking body and the plunger sleeve both cause the contact stress of the mechanism to be greatly.

(c) Besides the first effective mode, the mechanism can also add a second effective mode; when the braking mechanism is applied to engine braking, the engine has two braking modes, so that the reliability of the braking mechanism is greatly improved, and the number of grades of graded braking is increased. In an emergency situation, for example, when a main braking system and/or a retarder assembled on a vehicle transmission system are/is subjected to heat fading or other faults due to long-time work, or a vehicle is heavily loaded and has a steep gradient or a slope with a long gradient, and the like, the engine is required to output the maximum braking power, and in the situation, all cylinders adopt a first effective mode; and when the engine braking speed exceeds the second effective mode operable rotating speed range, in this case, the first effective mode is adopted by all cylinders or part of the cylinders according to the braking power demand. When the first effective mode is adopted, the valve lift curve of the working cylinder does not change along with factors such as the pressure in the cylinder and the like, the maximum valve lift is obtained, and the highest engine braking power output is further obtained. When a large braking power is required to be provided in a non-emergency situation, such as a heavy load/a long slope/a steep slope and the like of a vehicle, all the cylinders adopt a second effective mode; when a small braking power is needed in a non-emergency situation, such as a light load/a short slope/a gentle slope of the vehicle, the second effective mode is adopted by some cylinders. In the second effective mode, the valve lift of the working cylinder is changed by factors such as the cylinder pressure, and the braking power is reduced, but the cylinder pressure is significantly reduced, and the hydraulic buffer function is provided, so that the reliability of the braking mechanism is high. Compared with various existing brake mechanisms, the mechanism improves the maximum brake power output, increases the grade number of graded braking, covers a wider vehicle brake range, improves the use ratio of engine braking, reduces the use frequency and the strength of a main brake system and/or a retarder assembled on a vehicle transmission system, prolongs the service life of the retarder, and reduces the dust pollution of a friction type brake system. Compared with a pure mechanical brake mechanism (the effect of the composite brake mechanism is similar to that of a pure mechanical brake mechanism), the brake power of the brake mechanism in the first effective mode is improved, and the brake rotating speed ranges of the brake mechanism, the brake mechanism and the composite brake mechanism are not limited; the first effective mode is used for a short time only under the emergency condition, so that the service time of the first effective mode with larger stress of the mechanism is greatly shortened while the maximum braking power output of the engine is ensured, the service time of the second effective mode with low stress of the braking mechanism is increased, and the reliability of the mechanism is greatly improved. Compared with a pure hydraulic braking mechanism, the mechanism has a first effective mode and provides braking power output without the limitation of a braking rotating speed range and higher braking power; the mechanism also has a second effective mode, the maximum cylinder pressure is obviously reduced, the braking rotating speed range is obviously increased, the rotating speed range of the vehicle which runs in the second effective mode with higher reliability is increased, the use ratio of the vehicle is increased, and the reliability of the mechanism braking mechanism is improved. Therefore, the mechanism greatly improves the brake power output and the reliability of the brake mechanism at the same time, and increases the number of brake grades and the utilization ratio of engine brake. In addition, the mechanism can be applied to the technologies of engine cylinder deactivation, internal EGR and the like by adjusting different valve lift curves in an engine driving mode.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a structural schematic diagram of an embodiment 1 of the mechanism, and is a schematic diagram of a brake mechanism in a failure state and adopting a first hydraulic linkage valve.

FIG. 2a is the brake mechanism in the second effective state in the embodiment 1 and shows the structure of one embodiment of the first hydraulic linkage valve; FIG. 2b is a schematic view of the guiding arrangement between the plunger and the plunger sleeve; FIG. 2c is a schematic view of the guiding arrangement between the housing and the plunger barrel; fig. 2d shows the brake mechanism in the first active state and connected to the second oil chamber using two oil passages.

Fig. 3 is a schematic structural diagram of embodiment 2 of the present mechanism. Wherein figure 3a is a front view with the brake mechanism in a first active state; FIG. 3b is a cross-sectional view of section D-D of FIG. 3 a; figure 3c is a left side view with the brake mechanism in a failure state and figure 3c gives a schematic representation of the use of a second hydraulically linked valve.

FIG. 4 is a schematic representation of the use of a third hydraulic linkage valve.

Fig. 5 is a two-position three-way valve. Fig. 5a is a schematic view thereof, fig. 5b and fig. 5c are structural schematic views of an embodiment thereof, fig. 5b is a first position, and fig. 5c is a second position.

FIG. 6 is a first two position four way valve. Fig. 6a is a schematic view thereof, fig. 6b and fig. 6c are structural schematic views of an embodiment thereof, fig. 6b is a first position, and fig. 6c is a second position.

FIG. 7 is a second two position four way valve. Fig. 7a is a schematic view thereof, fig. 7b and 7c are structural schematic views of an embodiment thereof, fig. 7b is a first position, and fig. 7c is a second position.

FIG. 8 is a two position five way valve. Fig. 8a is a schematic view thereof, fig. 8b and 8c are structural schematic views of an embodiment thereof, fig. 8b is a first position, and fig. 8c is a second position.

Fig. 9 is a three-position four-way valve. Fig. 9a is a schematic view thereof, fig. 9b, 9c and 9d are structural schematic views of one embodiment thereof, fig. 9b is a first position, fig. 9c is a second position, and fig. 9d is a third position.

Fig. 10 is a first three-position, five-way valve. Fig. 10a is a schematic view thereof, fig. 10b, 10c and 10d are structural schematic views of one embodiment thereof, fig. 10b is a first position, fig. 10c is a second position, and fig. 10d is a third position.

Fig. 11 is a second three-position, five-way valve. Fig. 11a is a schematic view thereof, fig. 11b, 11c and 11d are structural schematic views of one embodiment thereof, fig. 11b is a first position, fig. 11c is a second position, and fig. 11d is a third position.

Fig. 12 is a three-position, six-way valve. Fig. 12a is a schematic view thereof, fig. 12b, fig. 12c and fig. 12d are structural schematic views of one embodiment thereof, fig. 12b is a first position, fig. 12c is a second position, and fig. 12d is a third position.

Fig. 13 is the effect of the present mechanism when applied to two-stroke braking and its comparison with the prior art, where fig. 13a and 13b are graphs comparing the braking power and maximum cylinder pressure in various braking modes, respectively, and fig. 13c is the stepped braking effect achieved by the present mechanism.

1. A shoulder; 2. a housing; 3. a collar; 4. a plunger sleeve; 5. a plunger; 6. a locking body; 7. a first channel; 8. a spring; 9. a spring seat; 10. a second channel; 11. a first hydraulic linkage valve; 12. a hydraulic control unit; 13. a one-way valve; 14. a first guide block; 15. a second guide block; 16. blocking; 17. a second hydraulic linkage valve; 18. a third hydraulic linkage valve; 19. a linkage piston rod; q1, a first oil chamber; q2, a second oil chamber; q3, a third oil chamber; a1, a first oil path; a2, a second oil path; a3, a third oil passage; a4, a fourth oil path; a5, a fifth oil path; h1, a slide valve body; h2, spool check valve; h3, spool valve mid port; h4, spool bushing; h5, spool check valve spring; h6, slide valve block; h7, spool valve spring; h8, a controlled port of the slide valve; h9, spool valve drive port; h10, slide valve drain port; HP, high pressure source; LP, a low pressure source; z1, adopting the mechanism and enabling all cylinders to work in a first two-stroke braking mode; z2, adopting the mechanism and enabling all cylinders to work in a second two-stroke braking mode; z3, adopting a pure mechanical mechanism and enabling all cylinders to work in a two-stroke braking mode; z4, adopting a pure hydraulic mechanism and enabling all cylinders to work in a two-stroke braking mode; z4, adopting a pure mechanical mechanism and enabling all cylinders to work in a four-stroke decompression braking mode; Z1L, adopting the mechanism and enabling a half of cylinders to work in a first two-stroke braking mode; Z2L, adopting the mechanism and enabling a half of cylinders to work in a second two-stroke braking mode; SZ2, adopting the mechanism to operate within a rotating speed range under a second two-stroke braking mode; SZ4, range of operable speeds using a pure hydraulic mechanism in a two-stroke braking mode. In the figure, the valve ports of all hydraulic valves are distinguished by single capital letters, wherein the P port is always connected with a high pressure source, and the T port is always connected with a low pressure source.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment discloses a high-efficiency multistage brake mechanism, which comprises a shell 2, a plunger sleeve 4, a plunger 5 and a hydraulic control unit 12, wherein the plunger sleeve 4 is arranged on the shell 2 and fixed or reciprocates relative to the shell 2, the plunger 5 is arranged on the plunger sleeve 4 and reciprocates relative to the plunger sleeve 4. When plunger sleeve 4 is fixed relative to housing 2, a second oil chamber Q2 is formed between plunger 5, plunger sleeve 4 and housing 2 or block 16 fixed relative to plunger sleeve 4. When plunger sleeve 4 reciprocates relative to housing 2, second oil chamber Q2 is formed between plunger 5 and plunger sleeve 4. The hydraulic control unit 12 is connected to the second oil chamber Q2 in various ways. The hydraulic control unit 12 is connected with the second oil chamber Q2 through a second oil path a2 and a hydraulic linkage valve, when the hydraulic control unit 12 connects the second oil path a2 with the high pressure source HP, hydraulic oil enters the second oil chamber Q2 only through a check valve arranged in the hydraulic linkage valve, and when the hydraulic control unit 12 connects the second oil path a2 with the low pressure source LP, hydraulic oil in the second oil chamber Q2 enters the second oil path a2 through the hydraulic linkage valve or directly enters the low pressure source LP. Alternatively, the hydraulic control unit 12 is connected to the second oil chamber Q2 through two oil passages, one of which is connected to the second oil chamber Q2 through the fourth oil passage a4 and the check valve 13 so as to be accessible, and the other of which is connected to the second oil chamber Q2 through the fifth oil passage a 5. And a limit device for limiting the maximum volume of the second oil chamber Q2 is arranged between the plunger sleeve 4 and the plunger 5. At least one first channel 7 is arranged on the side wall of the plunger sleeve 4, and a locking body 6 which reciprocates relative to the first channel 7 is arranged in the first channel 7. A first oil chamber Q1 is formed between plunger sleeve 4, housing 2, and lock body 6. The hydraulic control unit 12 is connected to the first oil chamber Q1 through a first oil passage a 1. The plunger 5 is provided with a locking body resetting mechanism.