CN107830081B

CN107830081B - Hydraulic booster cylinder

Info

Publication number: CN107830081B
Application number: CN201711263536.2A
Authority: CN
Inventors: 陈灵刚; 刘叶芝; 刘叶勇; 韩伟玉
Original assignee: Yuhuan Aoheng Machinery Co ltd
Current assignee: Yuhuan Aoheng Machinery Co ltd
Priority date: 2017-12-04
Filing date: 2017-12-04
Publication date: 2024-04-09
Anticipated expiration: 2037-12-04
Also published as: CN107830081A

Abstract

The invention provides a hydraulic power cylinder, and belongs to the technical field of machinery. The control device solves the problem that the external equipment is easy to be in a high-load state for a long time when the conventional control device is used. This hydraulic power cylinder, including the cylinder body that has inlet and liquid outlet, set up in the cylinder body the piston and be the rod-shaped impeller, inlet and liquid outlet can be linked together through seting up the liquid passageway that crosses on the piston, still have on the piston and be columnar liquid chamber that crosses, liquid passageway including seting up on crossing the liquid chamber lateral wall can with the liquid chamber with the inlet liquid passageway that is linked together, the impeller inner has the portion of crossing that stretches into liquid intracavity, crosses liquid portion and can be in cross along axial translation in the liquid chamber, cross the lateral part of liquid portion when liquid portion is in different positions and can partly block the inlet passageway or not block the inlet passageway to different degree. The hydraulic power cylinder has the advantage of high use safety.

Description

Hydraulic booster cylinder

Technical Field

The invention belongs to the technical field of machinery, relates to a hydraulic power-assisted cylinder, and particularly relates to a hydraulic clutch and brake power-assisted master cylinder.

Background

The clutch brake system is an important component of vehicle running and can be operated and controlled by adopting a mechanical control structure. However, as the power of the vehicle is continuously increased, the requirement for the torque transmission capability of the clutch is continuously increased, and if the torque reserve coefficient of the clutch is increased by increasing the pressing force of the spring or the like, the heavy feeling of stepping on the pedal is greatly increased, the labor intensity of a driver is increased, and the operation comfort is reduced. For this reason, a method of operating and assisting a clutch and brake system of a vehicle by a hydraulic booster is widely used.

For example, an operation method of a tractor clutch operating device with hydraulic assistance is designed and applied for Chinese patent (the application number of the tractor clutch operating device is 201510110056.7; the application number of the tractor clutch operating device is CN 104728309A), the operating device comprises an assistance oil cylinder, a piston, a valve rod, a block, a return spring and a safety valve, wherein the piston, the block and the return oil cavity are arranged in the assistance oil cylinder, the assistance oil cylinder is divided into a lower cavity, an upper cavity and an return oil cavity by the piston and the block and are respectively communicated with an oil inlet, an oil outlet and an oil return opening of the assistance oil cylinder, the valve rod penetrates through the piston and the block, an oil duct is arranged in the valve rod, one end of the oil duct is communicated with the lower cavity, the side part of the oil duct is communicated with the upper cavity, the other end of the oil duct is communicated with the return oil cavity by the safety valve, a throttle valve for connecting with a pedal is further arranged on the assistance oil cylinder, and the inner end of the throttle valve is provided with a conical head, and the conical head is opposite to a port of the oil duct, which is positioned in the lower cavity and can be plugged. When the hydraulic oil pump is used, an operator steps on the pedal to push the throttle valve to block the oil passage port, the pressure in the lower cavity is continuously increased along with the increase of oil entering from the oil inlet, the piston is pushed and the piston rod which extends out of the power-assisted oil cylinder and is correspondingly connected with the pedal moves upwards, namely, the oil pressure in the lower cavity is increased to push the piston and the piston rod to move so as to reduce the requirement on acting force of the pedal, and the labor intensity of the operator is reduced.

However, when the operating device is used, an external oil pump supplies oil to the power-assisted oil cylinder through the oil inlet, if an operator presses the pedal hard to make the throttle valve block the oil passage port, the oil pressure in the lower cavity can be continuously increased, the load born by equipment such as the external oil pump is also continuously increased, and the external equipment is in a high-load state for a long time, so that equipment failure or damage is easily caused.

Disclosure of Invention

The invention aims to solve the problems in the prior art, and provides a hydraulic power-assisted cylinder, which aims to solve the technical problem of reducing the load of external equipment on the basis that the power-assisted cylinder can play a normal auxiliary role.

The aim of the invention can be achieved by the following technical scheme:

the hydraulic power-assisted cylinder comprises a cylinder body with a liquid inlet and a liquid return opening, a piston arranged in the cylinder body and a rod-shaped pushing piece, wherein the liquid inlet and the liquid return opening can be communicated through a liquid passing channel arranged on the piston.

When the hydraulic booster cylinder is used, the outer end of the push piece extending out of the cylinder body is directly or indirectly connected with the pedal, when an operator steps on the pedal, inward acting force is applied to the push piece, so that the push piece drives the liquid passing part to move inwards towards the liquid passing part and to approach the piston until the push piece abuts against the piston at the bottom of the liquid passing part, at the moment, the liquid passing part does not completely block the liquid inlet channel, but partially block the liquid inlet channel, the flowable cross-sectional area of the part of the blocked liquid inlet channel is smaller than that of the part of the liquid inlet channel, namely, the smallest cross-sectional area of all the parts of the part of the liquid inlet channel, through which liquid medium can flow, is smaller than the smallest cross-sectional area of all the parts of the liquid inlet channel, through which liquid medium can flow, so that the flow through the liquid passing through the liquid inlet channel is reduced, the liquid inlet speed of the piston is larger than the liquid outlet speed, the pressure is continuously increased, and the pressure difference is formed between the piston and the side of the piston, and the piston, thus the auxiliary force can be pushed by the movement of the piston, and the labor intensity of the operator is reduced. Meanwhile, the liquid passing part of the hydraulic booster cylinder still only partially blocks the liquid inlet channel even when the liquid passing part is propped against the piston, namely, in the process that the pushing piece drives the liquid passing part to axially translate along the liquid passing part, the liquid passing channel is always in a communicated state, and liquid media supplied to the cylinder body by external equipment always flow to the liquid returning port through the liquid passing channel, so that the condition that the pressure of the piston close to one side of the liquid inlet continuously rises to cause the load of the external equipment to be overlarge is avoided, and the safety of the external equipment and vehicles using the hydraulic booster cylinder are ensured when the hydraulic booster cylinder is used. The liquid inlet channel is arranged on the side part of the liquid passing cavity, the flowing direction of liquid medium can be conveniently changed, the liquid passing part can conveniently block the liquid inlet channel through the side part, the resistance received during blocking is reduced, the effectiveness of partial blocking is ensured, the pressure difference can be stably generated on the two sides of the piston so as to push the piston to act to assist an operator to tread the pedal, and meanwhile, the condition that external equipment is overloaded due to the fact that liquid passing is conducted completely and blocked due to improper operation is avoided.

In the hydraulic power cylinder, the side part of the liquid passing part is provided with a convex annular convex shoulder, and the convex shoulder can approach the liquid inlet channel along with the liquid passing part and partially block the liquid inlet channel. The convex shoulder is used for blocking the liquid inlet channel, the port of the liquid inlet channel can be better closed, the partial blocking effect of the shoulder on the liquid inlet channel is better, the pressure difference can be stably generated on two sides of the piston to push the piston to act so as to assist an operator to tread the pedal, and meanwhile, the condition that external equipment is overloaded due to the fact that liquid passing conduction is completely blocked due to improper operation is avoided.

In the hydraulic power cylinder, a guide surface which is obliquely arranged is arranged on one side of the convex shoulder facing the liquid inlet channel port. The guide surface is arranged on the shoulder for partially blocking the liquid inlet channel, so that liquid medium at the port of the liquid inlet channel can flow out conveniently, the resistance of the shoulder when the shoulder partially blocks the liquid inlet channel is reduced, the smooth and stable blocking action is ensured, the auxiliary force is better provided for operators, and the operation intensity of the operators is reduced.

In the hydraulic power-assisted cylinder, the outer side of the liquid passing part is further provided with an annular protruding blocking shoulder, an annular sealing groove is formed between the protruding shoulder and the blocking shoulder, and an annular sealing element is arranged in the sealing groove. The two sides of the sealing element are limited through the shoulder and the retaining shoulder, so that the position of the sealing element is guaranteed not to be displaced or deformed due to long-time use, the effect of partially blocking the liquid passing channel is guaranteed, the pressure difference can be stably generated on the two sides of the piston so as to push the piston to act to assist an operator to tread the pedal, and meanwhile, the condition that external equipment is overloaded due to the fact that liquid passing conduction is completely blocked due to improper operation is avoided.

In the hydraulic power cylinder, the liquid inlet channel at least comprises a first liquid inlet hole and a second liquid inlet hole which are all arranged on the side part of the piston in a penetrating mode, and the outlet of the first liquid inlet hole is closer to the shoulder relative to the outlet of the second liquid inlet hole. The front and back positions of the first liquid inlet and the second liquid inlet are arranged, so that when the liquid passing part abuts against the piston, the sealing element on the side part of the liquid passing part can seal the first liquid inlet and does not seal the second liquid inlet or cooperate with the convex shoulder to partially block the second liquid inlet, the annular convex shoulder and the sealing element of the liquid passing part are matched in a staggered mode to form a scheme of partially blocking the liquid inlet channel, the structure is simpler, the sealing effect of partial blocking is more stable, the situation that the liquid passing channel is completely sealed due to long-term use is avoided, and the performance of reducing the load of external equipment is guaranteed.

In the hydraulic power cylinder, the liquid passing channel further comprises a liquid returning channel which can be used for communicating the liquid passing cavity with the liquid returning port, and an inlet of the liquid returning channel is formed in the bottom of the liquid passing cavity. The liquid return channel is convenient to open, and the flowing of the liquid medium is smoother.

In the hydraulic booster cylinder, the minimum cross-sectional area of the liquid inlet channel is smaller than the minimum cross-sectional area of the liquid return channel. The cross section area of the liquid inlet channel is smaller than that of the liquid return channel, so that the liquid medium flowing through the liquid inlet channel with smaller cross section can be more effectively reduced by blocking the liquid passing part.

In the hydraulic power cylinder, the liquid passing portion is barrel-shaped, the opening of the liquid passing portion faces to the outlet of the liquid passing cavity, the opening of the liquid passing portion can cover the outlet of the liquid passing cavity, the liquid inlet channel further comprises a liquid passing hole penetrating through the side portion of the liquid passing portion, a spring is further arranged in the liquid passing portion, and two ends of the spring are respectively abutted against the piston and the liquid passing portion. The opening of passing liquid portion can cover the export of passing the liquid chamber completely, can guarantee to cross liquid portion and support on the piston of entity steadily, do not appear the skew, and the through-hole through the lateral part cooperates the passing of liquid medium of the realization of the inner chamber of passing liquid portion, avoided passing the liquid portion port department to receive the condition of striking, further guaranteed the stability that crosses liquid portion and support on the piston, and then guaranteed the stability of crossing liquid portion when carrying out the partial blocking to the feed liquor passageway, reach the effect of stable pressure release for external equipment, avoid external equipment to be in the condition of high load state constantly, the spring sets up the inner wall that accessible crossed liquid portion in the barrel-shaped and provides the support to the spring, guarantee the stability that resets.

In the hydraulic power-assisted cylinder, the liquid passing portion and the pushing piece are of an integrated structure, a limiting piece is fixed on the piston at a position close to the port of the liquid passing cavity, the liquid passing portion can move back and forth in the liquid passing cavity along the axial direction of the pushing piece, and the piston can drive the liquid passing portion to move through the limiting piece. The piston can drive the liquid passing part and the pushing piece to synchronously move inwards through the limiting piece after moving inwards due to different pressures at two sides, so that the pushing piece is assisted to move inwards, and the labor intensity of operators is reduced.

In the hydraulic power cylinder, the cross-sectional area of the orifice of the first outlet of the liquid inlet is the smallest part of the first liquid inlet, and the cross-sectional area of the orifice of the second outlet of the liquid inlet is the smallest part of the second liquid inlet. The cross-sectional area of the outlet orifice is small, so that the blocking effect of the liquid passing part on the flow quantity of the liquid inlet channel is better.

In the hydraulic power cylinder, the liquid inlet channel comprises a side hole penetrating through the piston, and the side part of the liquid passing part can block the side hole after translation. The inlet channel may be provided as a single side hole only, as required, and may only partially block the side hole but not completely when the liquid passing portion abuts against the piston.

Compared with the prior art, when the hydraulic power-assisted cylinder is used, the liquid medium is always incompletely blocked from the liquid inlet cavity to the liquid passing channel flowing in the liquid return cavity, so that the liquid passing channel is in a normally open state, the liquid medium in the liquid inlet cavity can always flow into the liquid return cavity through the liquid passing channel and flow out from the liquid return port, the pressure in the liquid inlet cavity is reduced, the load of external liquid supply equipment is further reduced, and the use safety of external equipment and vehicles is ensured. Meanwhile, because the liquid medium is circulated through the liquid passing channel all the time, even if a vehicle using the hydraulic booster cylinder is flameout, part of oil still remains in the cylinder body, certain booster can be provided for the stepping of the pushing piece, the clutch pedal can still be stepped after flameout, convenience is provided for the use of the vehicle, and great help is provided for agricultural equipment in the labor process.

Drawings

Fig. 1 is a schematic sectional view of the hydraulic cylinder in which the hydraulic passage is completely opened.

Fig. 2 is an enlarged view of the hydraulic assist cylinder at the liquid passing portion when the liquid passing passage is fully opened.

Fig. 3 is a schematic sectional view of the hydraulic cylinder in which the fluid passage is partially blocked.

Fig. 4 is an enlarged view of the hydraulic cylinder at the liquid passing portion when the liquid passing passage is partially blocked.

Fig. 5 is a schematic sectional view of the hydraulic cylinder at the liquid inlet passage.

In the figure, 1, a cylinder body; 11. a liquid inlet; 12. a liquid return port; 13. a liquid inlet cavity; 14. a liquid return cavity; 2. a piston; 21. a liquid passage; 21a, a liquid return channel; 21b, a liquid inlet channel; 21c, a first liquid inlet hole; 21d, a liquid inlet hole II; 22. a liquid passing cavity; 3. a pushing member; 4. a liquid passing part; 41. a seal; 42. a liquid through hole; 43. shoulder; 43a, a guide surface; 44. a shoulder; 5. a spring; 6. and a limiting piece.

Detailed Description

The following are specific embodiments of the present invention and the technical solutions of the present invention will be further described with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

As shown in fig. 1 and 3, the hydraulic booster cylinder comprises a cylinder body 1 with a liquid inlet 11 and a liquid return 12, a piston 2 arranged in the cylinder body 1 and a rod-shaped pushing piece 3, wherein the piston 2 divides the cylinder body 1 into a liquid inlet cavity 13 communicated with the liquid inlet 11 and a liquid return cavity 14 communicated with the liquid return 12, and the liquid inlet cavity 13 and the liquid return cavity 14 are communicated through a liquid passage 21 arranged on the piston 2.

The piston 2 is recessed toward one end of the pushing member 3 and forms a cylindrical liquid passing cavity 22, the liquid passing channel 21 includes a liquid inlet channel 21b which is arranged at the side of the liquid passing cavity 22 and can communicate the liquid inlet cavity 13 with the liquid passing cavity 22, and a liquid returning channel 21a which can communicate the liquid passing cavity 22 with the liquid returning cavity 14, the inner end of the pushing member 3 is provided with a liquid passing portion 4, and the liquid passing portion 4 is positioned in the liquid passing cavity 22. The liquid passing part 4 can axially translate in the liquid passing cavity 22 under the action of the pushing piece 3, and when the liquid passing part 4 is positioned at different positions, the side part of the liquid passing part 4 can partially block the liquid inlet channel 21b or not block the liquid inlet channel 21b in different areas. That is, when the liquid passing portion 4 abuts against the piston 2, the side portion of the liquid passing portion 4 can partially block the liquid inlet passage 21b, and the flow-through cross-sectional area of the whole liquid passing passage 21 after being blocked is made smaller than that of the liquid inlet 11. In this embodiment, the blocking position of the liquid passing portion 4 is the position where the cross-sectional area of the liquid passing passage 21 is smallest, that is, the smallest cross-sectional area of the liquid inlet passage 21b is smaller than the smallest cross-sectional area of the liquid return passage 21 a.

As shown in fig. 2 and 4, the liquid passing cavity 22 is a columnar cavity with an opening facing the direction of the pushing member 3, the inlet of the liquid returning channel 21a is arranged at the bottom of the liquid passing cavity 22, the liquid passing portion 4 is barrel-shaped with an opening facing the inlet of the liquid returning channel 21a, and the opening of the liquid passing portion 4 can completely cover the inlet of the liquid returning channel 21 a. A gap through which the liquid medium flows is formed between the outside of the liquid passing portion 4 having the open end and the inner wall of the liquid passing chamber 22. The liquid inlet channel 21b includes a first liquid inlet 21c and a second liquid inlet 21d, which are all formed in the side of the piston 2, and a liquid through hole 42 formed in the side of the liquid passing portion 4. As shown in fig. 5, the number of the first liquid inlet holes 21c and the second liquid inlet holes 21d is several, and the axes of the liquid bypassing the liquid chamber 22 are distributed in a ring shape. If necessary, the cross-sectional area of the outlet of the first inlet 21c may be the smallest area of the first inlet 21c, and the cross-sectional area of the outlet of the second inlet 21d may be the smallest area of the second inlet 21 d.

The outside of the liquid passing part 4 is provided with a convex annular shoulder 43 and a convex annular blocking shoulder 44, an annular sealing groove is formed between the convex shoulder 43 and the blocking shoulder 44, an annular sealing piece 41 is arranged in the sealing groove, two sides of the sealing piece 41 can respectively abut against the side walls of the liquid passing part 4 and the liquid passing cavity 22 to realize sealing, the position of the liquid passing hole 42 is positioned between the convex shoulder 43 and the opening of the liquid passing part 4, the positions of the liquid inlet hole 21c and the liquid inlet hole 21d are positioned between the sealing piece 41 and the inlet of the liquid return channel 21a, and when the liquid passing part 4 is pushed by the pushing piece 3 to move inwards, the sealing piece 41 gradually approaches the liquid inlet hole 21c and the liquid inlet hole 21 d. In this embodiment, the outlet of the first inlet 21c is closer to the shoulder 43 than the outlet of the second inlet 21 d; the end of the shoulder 43 adjacent to the first inlet opening 21c has a guide surface 43a for facilitating the transport of the liquid medium in a direction away from the sealing member 41. The inside of the liquid passing part 4 is also provided with a spring 5, two ends of the spring 5 respectively lean against the bottom of the liquid passing cavity 22 and the bottom of the liquid passing part 4, and the liquid passing part 4 can push out the pushing piece 3 towards the outer end direction of the pushing piece 3 under the action of the elasticity of the spring 5.

The liquid passing part 4 and the pushing piece 3 are of an integrated structure, a limiting piece 6 is fixed at a port, close to the liquid passing cavity 22, of the piston 2, the liquid passing part 4 can move back and forth in the liquid passing cavity 22 along the axial direction of the pushing piece 3, and the piston 2 can drive the liquid passing part 4 and the pushing piece 3 to move synchronously through the limiting piece 6. In this embodiment, the limiting member 6 is a snap spring, and of course, a convex edge and other structures can be selected as required; the pushing piece 3 further comprises a push rod, a sliding block and a push rod which are all in a round rod shape, the push rod, the sliding block and the push rod are coaxially arranged in sequence and are connected into a whole, the outer end of the push rod extends out of the cylinder body 1 and is used for being correspondingly connected with the pedal, and the inner end of the push rod is connected with the liquid passing portion 4.

When the hydraulic booster cylinder is not used, under the action of the elasticity of the spring, the liquid passing part 4 and the pushing piece 3 move outwards, the liquid inlet cavity 13 is communicated with the liquid return cavity 14 through the unblocked liquid passing channel 21, liquid medium entering the cylinder body 1 from the liquid inlet 11 can enter the liquid return cavity 14 from the liquid inlet cavity 13 along the liquid passing channel 21, the pressure between the liquid inlet cavity and the liquid passing cavity 13 is balanced, and a normally open liquid medium conveying loop can be formed, so that even if a vehicle is flameout, oil still remains in the cylinder body 1, a certain auxiliary force can be provided for the movement of the piston 2 and the pushing piece 3, and the labor intensity of operators is reduced.

When the hydraulic power-assisted cylinder is used, an operator depresses a pedal to apply an inward moving acting force to the pushing piece 3, so that the liquid passing portion 4 is driven to gradually move towards the bottom direction of the liquid passing cavity 22. When the liquid passing part 4 abuts against the bottom of the liquid passing cavity 22, namely the piston 2, the sealing piece 41 on the side part of the liquid passing part 4 can completely block the liquid inlet hole I21 c on the side part of the liquid passing cavity 22 and cooperate with the shoulder 43 arranged adjacently to partially block the liquid inlet hole II 21d, so that the cross-sectional area of the liquid which can be discharged from the liquid inlet hole II 21d is smaller than the minimum cross-sectional area of the liquid inlet 11. At this time, the liquid medium fed into the liquid inlet cavity 13 by the external equipment is more than the liquid medium fed into the liquid return cavity 14 from the liquid inlet cavity 13, the pressure in the liquid inlet cavity 13 gradually rises, a pressure difference is formed between the liquid inlet cavity 13 and the liquid return cavity 14, and the piston 2 is pushed to move towards the liquid return cavity 14 under the action of the pressure difference. When the moving distance of the piston 2 is greater than that of the liquid passing part 4 relative to the piston 2, the limiting piece 6 abuts against the liquid passing part 4 and drives the liquid passing part 4 and the pushing piece 3 to move together with the piston 2, so that the acting force required by an operator to step on a pedal is reduced, and an auxiliary effect is achieved.

Here, even if the liquid passing portion 4 of the hydraulic booster cylinder still only partially blocks the liquid passing channel 21 when being abutted against the piston 2, so that the liquid passing channel 21 is always in a communicated state, the liquid medium supplied to the liquid inlet cavity 13 by the external equipment always flows to the liquid return cavity 14 through the liquid passing channel 21 and flows out from the liquid return port 12, the condition that the pressure in the liquid inlet cavity 13 continuously rises to cause the load of the external equipment to be overlarge is avoided, and the safety of the external equipment and a vehicle using the hydraulic booster cylinder is ensured when the hydraulic booster cylinder is used.

In addition, the piston 2 also separates the liquid outlet cavity from the cylinder body 1, the cylinder body 1 is also provided with a liquid outlet communicated with the liquid outlet cavity, the liquid outlet cavity is communicated with the liquid return cavity 14 through a liquid outlet channel, the liquid outlet channel is also provided with a central valve component, and the central valve component can open the liquid outlet channel when the pressure in the liquid return cavity 14 is large, and enables liquid medium to flow out from the liquid outlet through the liquid outlet cavity. A return spring capable of resetting the piston 2 is also arranged in the liquid return cavity 14 in the cylinder body 1.

In addition to the above technical solution, the liquid inlet channel 21b may include only a side hole penetrating through the piston 2, and the side portion of the liquid passing portion 4 may partially block the side hole after translation.

The specific embodiments described herein are offered by way of example only to illustrate the spirit of the invention. Those skilled in the art may make various modifications or additions to the described embodiments or substitutions thereof without departing from the spirit of the invention or exceeding the scope of the invention as defined in the accompanying claims.

Claims

1. The hydraulic booster cylinder comprises a cylinder body (1) with a liquid inlet (11) and a liquid return opening (12), a piston (2) arranged in the cylinder body (1) and a rod-shaped pushing piece (3), wherein the liquid inlet (11) and the liquid return opening (12) can be communicated through a liquid passing channel (21) arranged on the piston (2), and the hydraulic booster cylinder is characterized in that the piston (2) is also provided with a columnar liquid passing cavity (22), the liquid passing channel (21) comprises a liquid passing channel (21 b) arranged on the side wall of the liquid passing cavity (22) and capable of communicating the liquid passing cavity (22) with the liquid inlet (11), the inner end of the pushing piece (3) is provided with a liquid passing part (4) extending into the liquid passing cavity (22), the liquid passing part (4) can axially translate in the liquid passing cavity (22), when the liquid passing part (4) is in different positions, the side part of the liquid passing part can be in different degrees, the liquid passing part can be blocked by the liquid passing channel (21 b) or the liquid passing part (21 b) can be blocked by the liquid passing through the liquid passing part (4) and is in a convex shoulder part (43) and can be blocked by the liquid passing through the liquid passing part (21 b), the utility model provides a piston, including piston (2) side, feed liquor passageway (21 b) is including all running through feed liquor hole one (21 c) and feed liquor hole two (21 d) of seting up in piston (2) side, the export of feed liquor hole one (21 c) is nearer for the export of feed liquor hole two (21 d) shoulder (43), liquid passageway (21) still including can be with liquid passageway (21 a) that returns that liquid chamber (22) are linked together with return liquid mouth (12), the import of liquid passageway (21 a) is opened in the bottom of liquid chamber (22), liquid portion (4) are the bucket form, the opening of this liquid portion (4) orientation liquid chamber (22) export, and liquid portion (4) opening can cover liquid chamber (22) export, liquid passageway (21 b) still including running through set up in liquid portion (4) lateral part's liquid through hole (42), still be provided with spring (5) in liquid portion (4) and spring (4) offset both ends and piston (2) respectively.

2. A hydraulic cylinder according to claim 1, characterized in that the shoulder (43) has a guide surface (43 a) arranged obliquely on the side facing the port of the feed channel (21 b).

3. Hydraulic cylinder according to claim 1 or 2, characterized in that the outside of the liquid passing part (4) is also provided with a convex annular blocking shoulder (44), an annular sealing groove is formed between the convex shoulder (43) and the blocking shoulder (44), and an annular sealing element (41) is arranged in the sealing groove.

4. A hydraulic cylinder according to claim 1, characterized in that the smallest cross-sectional area of the feed channel (21 b) is smaller than the smallest cross-sectional area of the return channel (21 a).

5. The hydraulic power cylinder according to claim 1 or 2, wherein the liquid passing portion (4) and the pushing member (3) are of an integrated structure, a limiting member (6) is fixed on the piston (2) near a port of the liquid passing cavity (22), the liquid passing portion (4) can move back and forth in the liquid passing cavity (22) along the axial direction of the pushing member (3), and the piston (2) can drive the liquid passing portion (4) to move through the limiting member (6).

6. A hydraulic cylinder according to claim 1 or 2, characterized in that the feed channel (21 b) comprises a side hole which is open through the piston, the side of the liquid passing portion (4) being able to partly block the side hole after translation.