阅读说明：本技术 一种集成式低压补油排气阀驱动装置 (Integrated low-pressure oil supplementing exhaust valve driving device ) 是由 杨丽 于 2019-10-29 设计创作，主要内容包括：本发明属于发动机技术领域,公开了一种集成式低压补油排气阀驱动装置,包括第一壳体,轴向贯穿设有安装孔,安装孔包括第一孔和第二孔,第一孔的直径大于第二孔的直径,第一壳体的侧壁设有与第一孔连通的低压补油进油孔；单向阀,设置于连通低压补油进油孔的油路上；外活塞,滑动置于安装孔内,外活塞与第一孔之间形成有外腔；内活塞,滑动置于外活塞内,内活塞和外活塞之间形成有内腔,内腔能连通于外腔；阀杆,连接于内活塞的一端；液压转接块,固定安装于第一壳体,且开设有第一通孔,第一通孔的一端连通于第一孔；电磁阀,安装于液压转接块,且与第一通孔的另一端连通。本发明结构简单,集成化程度高,能够满足快速、高效排气的需求。(The invention belongs to the technical field of engines, and discloses an integrated low-pressure oil-supplementing exhaust valve driving device which comprises a first shell, wherein an installation hole axially penetrates through the first shell, the installation hole comprises a first hole and a second hole, the diameter of the first hole is larger than that of the second hole, and a low-pressure oil-supplementing oil inlet hole communicated with the first hole is formed in the side wall of the first shell; the check valve is arranged on an oil way communicated with the low-pressure oil supplementing inlet hole; the outer piston is arranged in the mounting hole in a sliding mode, and an outer cavity is formed between the outer piston and the first hole; the inner piston is arranged in the outer piston in a sliding manner, an inner cavity is formed between the inner piston and the outer piston, and the inner cavity can be communicated with the outer cavity; a valve rod connected to one end of the inner piston; the hydraulic transfer block is fixedly arranged on the first shell and is provided with a first through hole, and one end of the first through hole is communicated with the first hole; and the electromagnetic valve is arranged on the hydraulic transfer block and is communicated with the other end of the first through hole. The invention has simple structure and high integration degree, and can meet the requirements of quick and efficient exhaust.)

1. An integrated low-pressure oil-supplementing exhaust valve driving device is characterized by comprising:

the oil-supplementing device comprises a first shell (1), wherein a mounting hole axially penetrates through the first shell (1), the mounting hole comprises a first hole (11) and a second hole (12) which are communicated, the diameter of the first hole (11) is larger than that of the second hole (12), and a low-pressure oil-supplementing oil inlet hole (13) communicated with the first hole (11) is formed in the side wall of the first shell (1);

the check valve (2) is arranged on an oil way communicated with the low-pressure oil supplementing oil inlet hole (13) and is used for limiting the oil in the low-pressure oil supplementing oil inlet hole (13) to flow outwards;

the outer piston (3) is arranged in the mounting hole in a sliding mode, and an outer cavity is formed between the outer piston (3) and the first hole (11);

the inner piston (4) is arranged in the outer piston (3) in a sliding mode, an inner cavity is formed between the inner piston (4) and the outer piston (3), and the inner cavity can be communicated with the outer cavity;

a valve rod (5) connected to one end of the inner piston (4);

the hydraulic transfer block (6) is fixedly arranged on the first shell (1), a first through hole (61) is formed in the hydraulic transfer block (6), and one end of the first through hole (61) is communicated with the first hole (11);

and the electromagnetic valve (7) is arranged on the hydraulic transfer block (6) and is communicated with the other end of the first through hole (61).

2. The integrated low-pressure oil-replenishing exhaust valve driving device according to claim 1, wherein the side of the outer piston (3) is provided with a small throttling hole (31) communicating the outer chamber and the inner chamber.

3. The integrated low-pressure oil-replenishing exhaust valve driving device according to claim 2, wherein a second through hole (32) communicating the outer chamber and the inner chamber is provided at a side portion of the outer piston (3), the second through hole (32) is provided below the orifice (31) in the axial direction, and a diameter of the second through hole (32) is larger than that of the orifice (31).

4. The integrated low-pressure oil-supplementing and gas-exhausting valve driving device according to claim 3, wherein an annular groove (33) is opened on the outer piston (3), and one end of the second through hole (32) is communicated with the annular groove (33).

5. The integrated low-pressure oil-replenishing exhaust valve driving device according to claim 4, wherein the small throttling hole (31) is horizontally arranged, and a first distance L1 is formed between the upper end surface of the annular groove (33) and the top wall of the small throttling hole (31).

6. The integrated low-pressure oil-supplementing exhaust valve driving device according to claim 3, wherein an annular opening (41) is circumferentially opened at one end of the inner piston (4) which is not connected with the valve rod (5), and the outer cavity is communicated with the inner cavity through the throttling small hole (31) and/or the second through hole (32).

7. The integrated low-pressure oil-replenishing exhaust valve driving device according to claim 1, wherein the low-pressure oil-replenishing inlet hole (13) is horizontally arranged, and a second spacing L2 is formed between a bottom wall of the low-pressure oil-replenishing inlet hole (13) and a step surface at the junction of the first hole (11) and the second hole (12).

8. The integrated low-pressure oil-supplementing and gas-exhausting valve driving device according to claim 1, wherein a damping hole (14) is opened on a side wall of the first housing (1), and the damping hole (14) is communicated with the first hole (11).

9. The integrated low-pressure oil-supplementing and gas-exhausting valve driving device according to claim 1, wherein one end of the hydraulic transfer block (6) is provided with a boss (62), and the boss (62) is hermetically installed in one end of the first through hole (61).

10. The integrated low-pressure oil-replenishing exhaust valve driving device according to claim 1, wherein a passage (34) is formed in the outer piston (3), the inner piston (4) is slidably disposed in the passage (34), one end of the inner piston can extend out of the bottom of the passage (34), and an inner cavity is formed between the inner piston (4) and the passage (34).

Technical Field

The invention relates to the technical field of engines, in particular to an integrated low-pressure oil supplementing exhaust valve driving device.

Background

With the worldwide shortage of petroleum and the increasingly prominent global environmental pollution, in order to cope with the more and more severe energy situation, the high-efficiency, energy-saving and environment-friendly ship power generation product is becoming the focus of attention of all countries. The exhaust valve driving system is used as the influencer of the gas organization process and the combustion quality in the cylinder, and the quality of the product and the technical development directly restrict the development direction of the ship engine.

The electro-hydraulic control type exhaust valve driving system is gradually applied and popularized to marine intelligent ship engine products due to the advantages of intelligence, flexibility, accurate control and the like. However, most of the electro-hydraulic control exhaust valve driving systems widely used in the market at present are realized based on two sets of structures, namely, one set of independent control unit is matched with one set of independent driving unit, the structure is complex and heavy, the driving efficiency and the driving quality of the exhaust valve cannot be improved, and the development of the marine low-speed diesel engine towards a more intelligent direction is severely restricted.

Disclosure of Invention

The invention aims to provide an integrated low-pressure oil-supplementing exhaust valve driving device which is simple in structure and high in integration degree and can meet the requirements of quick and efficient exhaust.

In order to achieve the purpose, the invention adopts the following technical scheme:

an integrated low-pressure oil-replenishing exhaust valve driving device, comprising:

the oil-filling device comprises a first shell, a second shell and a sealing cover, wherein the first shell is axially provided with a mounting hole in a penetrating manner, the mounting hole comprises a first hole and a second hole which are communicated with each other, the diameter of the first hole is larger than that of the second hole, and the side wall of the first shell is provided with a low-pressure oil-filling inlet hole communicated with the first hole;

the check valve is arranged on an oil path communicated with the low-pressure oil supplementing oil inlet hole and used for limiting the oil in the low-pressure oil supplementing oil inlet hole to flow outwards;

the outer piston is arranged in the mounting hole in a sliding mode, and an outer cavity is formed between the outer piston and the first hole;

the inner piston is arranged in the outer piston in a sliding mode, an inner cavity is formed between the inner piston and the outer piston, and the inner cavity can be communicated with the outer cavity;

a valve stem connected to one end of the inner piston;

the hydraulic transfer block is fixedly arranged on the first shell and provided with a first through hole, and one end of the first through hole is communicated with the first hole;

and the electromagnetic valve is arranged on the hydraulic transfer block and is communicated with the other end of the first through hole.

Preferably, the side part of the outer piston is provided with a small throttling hole for communicating the outer cavity and the inner cavity.

Preferably, a second through hole communicating the outer cavity and the inner cavity is formed in the side portion of the outer piston, the second through hole is formed below the small throttling hole along the axial direction, and the diameter of the second through hole is larger than that of the small throttling hole.

Preferably, an annular groove is formed in the outer piston, and one end of the second through hole is communicated with the inside of the annular groove.

Preferably, the throttle orifice is horizontally disposed, and a first distance L1 is formed between an upper end surface of the annular groove and a top wall of the throttle orifice.

Preferably, an annular opening is formed in the circumferential direction of one end, which is not connected with the valve rod, of the inner piston, and the outer cavity is communicated with the inner cavity through the small throttling hole and/or the second through hole.

Preferably, the low-pressure oil supplementing inlet hole is horizontally arranged, and a second distance L2 is formed between the bottom wall of the low-pressure oil supplementing inlet hole and a step surface at the joint of the first hole and the second hole.

Preferably, a damping hole is formed in a side wall of the first housing, and the damping hole is communicated with the first hole.

Preferably, one end of the hydraulic transfer block is provided with a boss, and the boss is hermetically mounted in one end of the first through hole.

Preferably, a channel is formed in the outer piston, the inner piston is slidably arranged in the channel, one end of the inner piston can extend out of the bottom of the channel, and an inner cavity is formed between the inner piston and the channel.

The invention has the beneficial effects that: the structure of the invention realizes the integration of the driving device, has simple structure, and can meet the requirements of the marine diesel engine and the dual-fuel engine on quick and efficient exhaust of most fuel engines.

Drawings

FIG. 1 is a sectional view of an integrated low pressure oil replenishment vent valve driving device according to the present invention;

FIG. 2 is an enlarged schematic view taken at A of FIG. 1 in accordance with the present invention;

FIG. 3 is a schematic view of the integrated low-pressure oil-replenishing exhaust valve driving device according to the present invention in a state of low-pressure oil replenishment;

FIG. 4 is a schematic view showing the state of the valve rod of the integrated low-pressure oil-replenishing exhaust valve driving device according to the present invention during the opening process;

fig. 5 is a schematic view illustrating a state in which a valve rod of the integrated low-pressure oil-replenishing exhaust valve driving device according to the present invention is fully opened.

In the figure:

1. a first housing; 11. a first hole; 12. a second hole; 13. a low-pressure oil supplementing inlet hole; 14. a damping hole; 15. a third aperture; 2. a one-way valve; 3. an outer piston; 31. a small orifice; 32. a second through hole; 33. an annular groove; 34. a channel; 4. an inner piston; 41. an annular opening; 5. a valve stem; 6. a hydraulic transfer block; 61. a first through hole; 62. a boss; 7. an electromagnetic valve; 8. a valve housing; 9. a valve seat.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "right", etc. are used in an orientation or positional relationship based on that shown in the drawings only for convenience of description and simplicity of operation, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have a special meaning.

The invention provides an integrated low-pressure oil supplementing exhaust valve driving device which can meet the requirements of a marine diesel engine and a dual-fuel engine on quick and efficient exhaust of multi-fuel engines. As shown in fig. 1, the integrated low-pressure oil-supplementing exhaust valve driving device includes a first housing 1, a check valve 2, an outer piston 3, an inner piston 4, a valve rod 5, a hydraulic transfer block 6, an electromagnetic valve 7, a valve housing 8 and a valve seat 9, wherein the hydraulic transfer block 6, the first housing 1, the valve housing 8 and the valve seat 9 are sequentially connected from top to bottom (shown in fig. 1), the outer piston 3 is disposed in the first housing 1, the inner piston 4 is slidably disposed in the outer piston 3, one end of the valve rod 5 is disposed in the first housing 1, and the other end of the valve rod sequentially penetrates through the valve housing 8 and the valve seat 9, so as to open and close the exhaust valve.

In this embodiment, as shown in fig. 1, the first housing 1 is provided with a mounting hole axially penetrating therethrough, the mounting hole has a stepped hole structure, and includes a first hole 11, a second hole 12, and a third hole 15 sequentially connected to each other, wherein a diameter of the first hole 11 is larger than a diameter of the second hole 12, and a diameter of the third hole 15 is larger than a diameter of the first hole 11. The hydraulic transfer block 6 may be connected to the top of the first bore 11, the outer piston 3 may slide in the first bore 11, and an outer chamber may be formed between the first bore 11 and the outer piston 3. One end of the above-mentioned valve rod 5 can be placed in the second hole 12 and the other end is arranged through the third hole 15, the valve housing 8 and the valve seat 9 in order.

And a low-pressure oil supplementing inlet hole 13 communicated with the first hole 11 is formed in the side wall of the first shell 1, and the low-pressure oil supplementing inlet hole 13 is used for supplementing low-pressure oil into the outer cavity. Optionally, the check valve 2 is disposed on a pipeline communicating with the low-pressure oil supplementing inlet 13, and the conducting direction of the check valve 2 is opposite to the direction from the outside of the first housing 1 to the outer cavity, that is, low-pressure oil in the pipeline communicating with the low-pressure oil supplementing inlet 13 can flow into the low-pressure oil supplementing inlet 13 through the check valve 2 and then flow into the outer cavity, and the oil in the low-pressure oil supplementing inlet 13 cannot flow out through the check valve 2.

A damper hole 14 is further provided in the side wall of the first casing 1, the damper hole 14 is communicated with the first hole 11, and the oil in the outer chamber flows out through the damper hole 14 in a small amount.

The outer piston 3 is in a stepped cylindrical structure, and as shown in fig. 1, the outer piston 3 may include a first section and a second section, wherein the first section is slidably disposed in the first hole 11 and is capable of forming an outer cavity with the first hole 11, the second section is disposed in the second hole 12, and an end portion of the second section, which is not connected to the first section, is capable of being disposed in the third hole 15 when the outer piston 3 slides downward.

The inner piston 4 is slidably disposed in the outer piston 3, for example, a channel 34 may be formed in a central position of the outer piston 3, the channel 34 is disposed through one end of the outer piston 3 near the valve rod 5, the inner piston 4 is slidably disposed in the channel 34, and an inner cavity is formed between the inner piston 4 and the channel 34. The inner cavity can be communicated with the outer cavity, and oil in the outer cavity can flow into the inner cavity to drive the inner piston 4 to drive the valve rod 5 to slide downwards. The oil in the inner chamber can also be pressed out by the inner piston 4 and flows into the outer chamber.

As shown in fig. 2, an annular opening 41 is opened in the circumferential direction at one end of the inner piston 4 to which the stem 5 is not connected, and the annular opening 41 facilitates the oil in the outer chamber to flow into the inner chamber.

Preferably, a small orifice 31 for throttling is provided at a side portion of the outer piston 3 to communicate the outer chamber with the inner chamber, and the oil in the outer chamber can flow into the inner chamber through the small orifice 31.

The side part of the outer piston 3 is also provided with a second through hole 32 for communicating the outer cavity and the inner cavity, the second through hole 32 is axially arranged below the small throttling hole 31, and the diameter of the second through hole 32 is larger than that of the small throttling hole 31. Through this second through-hole 32, can make the fluid of outer intracavity pass in and out in the inner chamber fast, and then just also make inner piston 4 driven quick propelling valve rod 5 open, perhaps discharged the fluid of inner chamber by the inner piston 4 of valve rod 5 drive fast to the realization is closed fast to valve rod 5.

In this embodiment, it should be noted that, when the inner piston 4 does not slide, the annular opening 41 on the inner piston 4 communicates with the small throttling hole 31 and a small portion of the second through hole 32 (or does not communicate with the second through hole 32), at this time, when the low-pressure oil is supplemented, the oil in the low-pressure oil supplementing inlet 13 mainly enters the inner cavity through the outer cavity and the small throttling hole 31, and a small portion of the oil can enter the inner cavity through the second through hole 32 (when the annular opening 41 communicates with the small portion of the second through hole 32).

Preferably, the low-pressure oil supply hole 13 is horizontally disposed, and a second distance L2 is formed between a bottom wall of the low-pressure oil supply hole 13 and a step surface at a connection portion of the first hole 11 and the second hole 12. This second interval L2's setting, can be when outer piston 3 and interior piston 4 drive valve rod 5 and move to opening the end (specifically indicate valve rod 5 will open the at utmost promptly), the existence of this second interval L2 corresponding space interior fluid for the step face that first section and the second section junction of outer piston 3 formed can not direct collision on the step face of first hole 11 and second hole 12 junction, can form the buffering between outer piston 3 and first casing 1 promptly, avoids outer piston 3 and first casing 1 to receive the damage. With this arrangement, noise generated by collision between the outer piston 3 and the first housing 1 can be avoided.

As shown in fig. 2, an annular groove 33 is formed in the outer piston 3, specifically, the annular groove 33 is formed in the second section, one end of the second through hole 32 is communicated with the annular groove 33, and the oil in the outer cavity can enter the second through hole 32 through the annular groove 33 and then enter the inner cavity through the second through hole 32.

Alternatively, the small orifice 31 is horizontally disposed, and a first distance L1 (shown in fig. 2) is formed between the top wall of the small orifice 31 and the upper end surface of the annular groove 33 (i.e., the step surface formed at the junction of the first segment and the second segment). Through the setting of this first interval L1, when outer piston 3 and interior piston 4 drive valve rod 5 and move to opening the end (specifically indicate that valve rod 5 will open the at utmost promptly), second through-hole 32 is sealed by the pore wall of second hole 12 this moment, fluid in the space between the step face that first section and second section junction formed and the step face that first hole 11 and second hole 12 junction formed can be impressed throttle aperture 31, and get into the inner chamber through throttle aperture 31, make valve rod 5 move to opening when the end, leave fluid in the inner chamber, this fluid can avoid appearing the rigid collision between outer piston 3 and the interior piston 4, just can form the buffering between interior piston 4 and the outer piston 3, avoid inner piston 4 and outer piston 3 impaired. Further, with this arrangement, noise generated by collision of the outer piston 3 with the inner piston 4 can be avoided.

In this embodiment, a reset assembly (not shown) may be provided on the valve stem 5, and the reset assembly is used to reset the valve stem 5. Preferably, in this embodiment, the reset component may be an air spring, the air spring is slidably attached to the inner wall of the third hole 15, and a sealing member is disposed between the air spring and the inner wall of the third hole 15, and the sealing member is capable of slidably sealing the air spring and the third hole 15 when the air spring slides relative to the third hole 15.

The hydraulic transfer block 6 is fixedly mounted on the first housing 1, and a first through hole 61 is formed in the hydraulic transfer block 6, and one end of the first through hole 61 is communicated with the first hole 11. In this embodiment, a boss 62 may be disposed at one end of the hydraulic transfer block 6, and the boss 62 extends into one end of the first hole 11 and is sealed with the first hole 11 by a sealing member. In this embodiment, the first through hole 61 may be an L-shaped through hole, and the first through hole 61 is disposed through the boss 62.

The electromagnetic valve 7 is installed on one side of the hydraulic transfer block 6, and the electromagnetic valve 7 is communicated with the other end of the first through hole 61 and is used for controlling the on-off of oil entering the first through hole 61. That is, when the electromagnetic valve 7 is opened, the oil can enter the first through hole 61 and enter the outer chamber through the first through hole 61, thereby achieving driving of the outer piston 3. In addition, the present embodiment integrally mounts the solenoid valve 7 on the hydraulic relay block 6, which improves the integration of the entire drive apparatus.

The operation principle of the integrated low-pressure oil-supplementing exhaust valve driving device of the embodiment is as follows:

at the initial low pressure oil supply, as shown in fig. 3, the outer piston 3 and the inner piston 4 are both in the initial position, and the valve rod 5 is closed at this time. The low-pressure oil is pumped in through external equipment, the low-pressure oil enters the low-pressure oil supplementing oil inlet hole 13 through the check valve 2 and is supplemented into the outer cavity through the low-pressure oil supplementing oil inlet hole 13, when the oil in the outer cavity reaches a high position, the oil enters the inner cavity through the throttling small hole 31 in the outer piston 3 (if the annular opening 41 in the inner piston 4 is communicated with the small second through hole 32, a part of oil can also enter the inner cavity through the second through hole 32), and the oil supplementation is completed until the inner cavity and the outer cavity are completely filled with the low-pressure oil, and the action instruction of the whole machine is waited.

When the whole machine needs to intake and exhaust, the electromagnetic valve 7 is powered on and opened, high-pressure oil enters the first through hole 61 of the hydraulic transfer block 6 through the electromagnetic valve 7 and enters an upper chamber of the outer chamber (namely, a space between the boss hole 62 of the hydraulic transfer block 6 and the outer piston 3 and the first hole 11) through the first through hole 61, and meanwhile, because the acting area of the oil in the upper chamber of the outer chamber is larger than the sum of the acting area of a lower chamber of the outer chamber (namely, a space between a step surface at the joint of the first section and the second section and a step surface at the joint of the first hole 11 and the second hole 12) and the acting area of the inner chamber, the oil in the lower chamber of the outer chamber and the acting area of the inner chamber are pressurized, and when the acting force of the pressurized high-pressure oil on the inner piston 4 is larger.

Because the annular area of the outer cavity is larger than that of the inner cavity, oil in the outer cavity enters the inner cavity through the small throttling holes 31 and part of the second through holes 32 on the outer piston 3 in the descending process, the moving distance of the inner piston 4 is larger than that of the outer piston 3 (the moving distance ratio of the inner piston to the outer piston is the ratio of the acting areas of the oil in the inner cavity and the oil in the outer cavity), and when the second through holes 32 are completely communicated with the inner cavity (as shown in fig. 4), the valve rod 5 descends and accelerates. When the valve rod 5 runs to the tail end of the stroke, the second through hole 32 in the outer piston 3 is blocked by the first shell 1, oil in the outer cavity enters the inner cavity through the small throttling hole 31 in the outer piston 3 and a gap between the outer piston 3 and the first shell 1, the oil filling flow in the inner cavity is reduced, the running speed of the valve rod 5 is reduced, and the tail end of the stroke of the valve rod 5 is buffered. Finally, the small throttling hole 31 on the outer piston 3 is blocked by the first shell 1, the inner cavity and the outer cavity are separated, the inner piston 4 and the outer piston 3 stop running and are buffered by residual oil in the inner cavity, the valve rod 5 reaches a designed stroke (shown in figure 5), the electromagnetic valve 7 is powered off and closed, and a small distance is reserved between the outer piston 3 and the first shell 1 at the moment, so that the purpose of buffering the impact between the outer piston 3 and the first shell 1 is achieved.

When the whole machine finishes air inlet and exhaust, the control system controls the electromagnetic valve 7 to be electrified and opened, the valve rod 5 pushes the inner piston 4 to move upwards under the action of the reset assembly, the inner cavity and the outer cavity are not communicated because the second through hole 32 and the small throttling hole 31 are still closed by the second hole 12 at the moment, the inner piston 4 and the outer piston 3 synchronously move upwards under the drive of reset force and low-pressure oil in the low-pressure oil supplementing oil inlet hole 13, and the oil in the upper cavity of the outer cavity flows out through the first through hole 61. Along with the synchronous ascending of the inner piston 4 and the outer piston 3, the second through hole 32 is opened, the inner cavity is communicated with the outer cavity through the second through hole 32, the pressure between the inner cavity and the outer cavity is increased, the low-pressure oil supplement is closed, and the valve rod 5 ascends and accelerates.

When the valve rod 5 moves upwards to the stroke end (namely, closing is about to be performed), the outer piston 3 returns to the original position, and because a part of low-pressure oil is supplied into the outer cavity at the initial closing moment of the valve rod 5, and in the process of returning the outer piston 3 to the original position, the surplus oil is discharged through the damping hole 14, and seating buffering of the valve rod 5 is further realized.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Numerous obvious variations, adaptations and substitutions will occur to those skilled in the art without departing from the scope of the invention. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.