CN111425476B

CN111425476B - Hydraulic cylinder

Info

Publication number: CN111425476B
Application number: CN202010233261.3A
Authority: CN
Inventors: 不公告发明人
Original assignee: Longyan Shanli Engineering Hydraulic Co ltd
Current assignee: Longyan Shanli Engineering Hydraulic Co ltd
Priority date: 2020-03-29
Filing date: 2020-03-29
Publication date: 2022-11-22
Anticipated expiration: 2040-03-29
Also published as: CN111425476A

Abstract

The invention relates to the field of hydraulic cylinders, and discloses a hydraulic cylinder with a buffering function, which comprises a cylinder body, a cylinder barrel and a piston; the cylinder body is provided with an A port and a B port, the cylinder barrel is provided with a first through hole and a second through hole, and the cylinder barrel is positioned in the cylinder body and can reciprocate relative to the cylinder body; the piston is positioned in the cylinder barrel and divides the interior of the cylinder barrel into a first control cavity and a second control cavity; the first control cavity is communicated with the port A through the first through hole, the second control cavity is communicated with the port B through the second through hole, the piston reciprocates relative to the cylinder body under the action of medium pressure between the first control cavity and the second control cavity, and when the piston moves to the terminal position of any control cavity, the cylinder barrel moves relative to the cylinder body, so that the flow area between the through hole communicated with the control cavity and the port A or the port B is reduced, and the medium discharge speed in the control cavity is reduced. The hydraulic cylinder disclosed by the invention not only can realize effective deceleration and buffering in the reciprocating motion process of the piston, but also is simple in structure and easy to machine and manufacture.

Description

Hydraulic cylinder

Technical Field

The invention belongs to the technical field of hydraulic cylinders, and particularly relates to a hydraulic cylinder with a buffering function.

Background

The hydraulic cylinder is a hydraulic actuator that converts hydraulic energy into mechanical energy and performs linear reciprocating motion (or oscillating motion). When the hydraulic cylinder is used for realizing reciprocating motion, a speed reduction device can be omitted, a transmission gap is not formed, the motion is stable, and the hydraulic cylinder is widely applied to various hydraulic systems. When the hydraulic cylinder moving at a high speed moves to the end, a large impact is generated, and in order to reduce the impact, a hydraulic buffer device is usually added at the end of the hydraulic cylinder.

The existing hydraulic cylinder buffer devices are various in types, but essentially, a section of matching surface is added in front of and behind a piston, an oil return cavity is divided into a buffer cavity and an oil return cavity, wherein oil in the buffer cavity flows to the oil return cavity through a throttling port, so that back pressure is generated in the buffer cavity, the motion of the piston is prevented, the motion speed of the piston is reduced, and the purpose of reducing impact is achieved. According to the change of the area of the throttling port, two buffer types of fixed throttling and variable throttling are adopted; when the fixed throttling is started to buffer, the generated buffer braking force is large, but the buffer pressure is quickly attenuated, the buffer pressure hardly plays a role in the later period, and the buffer effect is poor; the variable-throttle buffering device changes the flow area along with the change of the buffering stroke in the buffering process, the pressure change at the initial buffering stage is relatively smooth when a conical surface is adopted, but the pressure mutation at the later stage is very large, and the ideal buffering effect can be achieved when a parabola is adopted, but the numerical control machine tool is required for processing, the cost is high, and the pressure mutation exists when the buffering starts and ends.

In addition, in order to achieve a better buffering effect, the concentricity of the buffering device and the cylinder barrel or the end cover must be ensured, so that the matching precision of the end cover and the piston rod, the matching precision of the cylinder barrel and the end cover, the matching precision of the cylinder barrel and the piston, the matching precision of the piston and the piston rod, the matching precision of the buffering sleeve and the piston rod and the matching precision of the buffering sleeve and the end cover are required to be ensured in the processing process, on one hand, the processing difficulty is increased, on the other hand, because the accumulation of errors has uncontrollable performance, the buffering effects of two hydraulic cylinders with the same processing precision are inconsistent, and the final buffering effect of the hydraulic cylinder cannot be ensured.

Disclosure of Invention

The invention provides a hydraulic cylinder with a buffering function, which aims to improve the deceleration buffering effect in the reciprocating motion process of a piston in the hydraulic cylinder. The hydraulic cylinder comprises a cylinder body, a cylinder barrel and a piston; the cylinder body is provided with an A port and a B port, the cylinder barrel is provided with a first through hole and a second through hole, and the cylinder barrel is positioned in the cylinder body and can reciprocate relative to the cylinder body; the piston is positioned in the cylinder barrel, and the interior of the cylinder barrel is divided into a first control cavity and a second control cavity which are not communicated with each other; a piston rod is arranged at one end of the piston, and the piston rod penetrates through the first control cavity and extends out of the cylinder body; the first control cavity is communicated with the port A through the first through hole, the second control cavity is communicated with the port B through the second through hole, and the piston reciprocates relative to the cylinder body under the action of medium pressure between the first control cavity and the second control cavity;

when the piston moves to the terminal position of the first control cavity, the cylinder barrel moves relative to the cylinder body, so that the flow area between the first through hole and the port A is reduced, and the speed of the medium in the first control cavity flowing back to the port A through the first through hole is reduced; when the piston moves to the terminal position of the second control cavity, the cylinder barrel moves relative to the cylinder body, the flow area between the second through hole and the port B is reduced, and the speed of the medium in the second control cavity flowing back to the port B through the second through hole is reduced.

Preferably, the cylinder barrel is rotatably connected with the cylinder body in the circumferential direction; when the piston moves to the terminal position of the first control cavity, the cylinder barrel rotates relative to the cylinder body in the circumferential direction, so that the flow area between the first through hole and the port A is reduced; when the piston moves to the terminal position of the second control cavity, the cylinder barrel rotates relative to the cylinder body in the circumferential direction, and the flow area between the second through hole and the port B is reduced.

Further preferably, the cylinder body is provided with a first annular groove, a first U-shaped groove, a first oil path, a second annular groove, a second U-shaped groove and a second oil path; the first annular groove and the second annular groove are respectively positioned on the inner surfaces of two ends of the cylinder body, the first U-shaped groove is used for communicating the first annular groove with the port A, and the second U-shaped groove is used for communicating the second annular groove with the port B; the first through hole is communicated with the port A through the first U-shaped groove, and the second through hole is communicated with the port B through the second U-shaped groove;

when the piston moves to the terminal position of the first control cavity, the cylinder barrel rotates relative to the cylinder body in the circumferential direction, so that the flow area between the first through hole and the first U-shaped groove is reduced, the flow area between the second through hole and the second U-shaped groove is increased, and the port A and the first control cavity are communicated through the first oil path;

when the piston moves to the terminal position of the second control cavity, the cylinder barrel rotates in the circumferential direction relative to the cylinder body, so that the flow area between the second through hole and the second U-shaped groove is reduced, the flow area between the first through hole and the first U-shaped groove is increased, and the port B and the second control cavity are communicated through the second oil path.

Further preferably, the first oil path and the second oil path are uniformly distributed on the cylinder body, the first oil path is provided with a first one-way valve, and the second oil path is provided with a second one-way valve; an inlet of the first one-way valve is communicated with the first annular groove, and an outlet of the first one-way valve is communicated with the first control cavity; an inlet of the second one-way valve is in communication with the second annular groove and an outlet of the second one-way valve is in communication with the second control chamber.

Preferably, the hydraulic cylinder is provided with two control rods, and two ends of the cylinder barrel are respectively provided with an inner spiral groove; the two control rods are respectively located at the terminal positions of the first control cavity and the second control cavity, the horizontal sections of the two control rods are axially opposite to the piston and can perform axial reciprocating linear motion, and the vertical sections of the two control rods are respectively connected with the two inner spiral grooves and can perform reciprocating sliding in the inner spiral grooves.

Further preferably, the cylinder body is provided with a guide groove; the guide groove is axially arranged, and the vertical section of the control rod is positioned in the guide groove to perform axial reciprocating linear motion.

Preferably, the hydraulic cylinder is also provided with a positioning assembly; the positioning assembly is located between the cylinder body and the cylinder barrel and used for positioning the position of the cylinder barrel, which moves to and fro relative to the cylinder body.

Further preferably, the positioning assembly comprises a positioning hole, a positioning spring, a positioning ball and a positioning groove; the positioning hole and the positioning groove are respectively positioned on the cylinder body and the cylinder barrel, and the positioning spring and the positioning ball are positioned in the positioning hole; in the reciprocating motion process of the cylinder barrel, the positioning ball compresses the positioning spring to be kept in the positioning hole, after the cylinder barrel moves in place, one end of the positioning ball is located in the positioning hole, and the other end of the positioning ball extends out of the positioning groove.

Preferably, the cylinder body adopts a split type structure, wherein the two ends of the cylinder body adopt a detachable cover plate structure.

Preferably, the piston adopts a step structure, so that the first control cavity and the second control cavity exist all the time.

Compared with the hydraulic cylinder with the existing structure, the hydraulic cylinder has the following beneficial technical effects:

1. in the invention, the cylinder barrel is arranged between the cylinder body and the piston, and when the piston moves to the terminal positions of the first control cavity and the second control cavity, the cylinder barrel rotates relative to the cylinder body in the circumferential direction to adjust the flow area between the port A and the port B and between the first control cavity and the second control cavity, so that the discharge speed of a medium in the control cavity is reduced, the motion resistance to the piston is gradually improved, and the aim and the effect of decelerating and buffering the piston are achieved. Meanwhile, the requirements on the machining and matching precision of the buffer device are reduced, the structure of the whole hydraulic cylinder is simplified, the high-requirement machining and manufacturing of complex parts are avoided, the machining difficulty of the whole hydraulic cylinder is reduced, the machining and manufacturing are facilitated, and the machining cost is saved.

2. In the invention, the annular groove, the U-shaped groove, the oil way and the one-way valve are distributed on the inner surfaces of the two ends of the cylinder body, so that the pressure medium in the annular groove can be unidirectionally drained to the control cavity by the oil way to form a driving force for the piston to move in the opposite direction. Therefore, after the through hole and the U-shaped groove are completely closed to complete the deceleration buffer effect on the piston, the pressure medium can be quickly and effectively drained to the control cavity by utilizing the oil way and the one-way valve, so that an effective reverse motion driving force is formed on the piston, and the effective reciprocating motion of the piston is ensured.

Drawings

FIG. 1 is a schematic structural view of a hydraulic cylinder according to the present embodiment with a piston rod in a retracted state;

FIG. 2 is a schematic structural diagram of the hydraulic cylinder according to the present embodiment with the piston rod in an extended state;

FIG. 3 is a schematic view of an outline structure of a cylinder body in the hydraulic cylinder of the present embodiment;

FIG. 4 is a schematic view of a first angular profile of a cylinder tube of the hydraulic cylinder of the present embodiment;

FIG. 5 is a schematic view of a second angular profile structure of the cylinder tube of the hydraulic cylinder of the present embodiment;

fig. 6 is an enlarged view of a portion of the structure at C in fig. 1.

Detailed Description

The technical solution of the present invention will be further described in detail with reference to the accompanying drawings and embodiments.

Referring to fig. 1 to 5, the hydraulic cylinder of the present embodiment includes a cylinder body 1, a cylinder tube 2, and a piston 3. Wherein, the cylinder body 1 is provided with a port A and a port B, the cylinder barrel 2 is provided with a first through hole 21 and a second through hole 22, and the cylinder barrel 2 can rotate reciprocally relative to the cylinder body 1 in the cylinder body 1. The piston 3 is located inside the cylinder tube 2, and divides the inside of the cylinder tube 2 into a first control chamber 23 and a second control chamber 24 that are not communicated with each other. A piston rod 31 is provided at one end of the piston 3, and the piston rod 31 protrudes to the outside of the cylinder 1 through the first control chamber 23. The first control chamber 23 is communicated with the port A through the first through hole 21, the second control chamber 24 is communicated with the port B through the second through hole 22, and the piston 3 reciprocates relative to the cylinder body 1 under the action of medium pressure between the first control chamber 23 and the second control chamber 24.

When the piston 3 moves to the terminal position of the first control cavity 23, the cylinder barrel 2 rotates in the circumferential direction relative to the cylinder body 1, so that the flow area between the first through hole 21 and the port A is reduced, the speed of the medium in the first control cavity 23 flowing back to the port A through the first through hole 21 is reduced, resistance is formed in the process that the piston 3 moves to the terminal position of the first control cavity 23, and the speed reducing and buffering effects are achieved.

When the piston 3 moves to the terminal position of the second control cavity 24, the cylinder barrel 2 rotates in the circumferential direction relative to the cylinder body 1 again, so that the flow area between the second through hole 22 and the port B is reduced, the speed of the medium in the second control cavity 24 flowing back to the port B through the second through hole 22 is reduced, resistance is formed in the process that the piston 3 moves to the terminal position of the second control cavity 24, and the speed reducing and buffering effects are achieved.

As shown in fig. 1, 2, and 5, two control rods 4 are provided in the hydraulic cylinder of the present embodiment, and inner spiral grooves 25 are provided at both end portions of the cylinder tube 2, respectively. Two control rods 4 are respectively located the terminal position of first control chamber 23 and the terminal position of second control chamber 24 to the horizontal section of two control rods 4 all is laid along the axial with piston 3 relatively and can carry out the reciprocal linear motion of axial, and the vertical section of two control rods 4 is connected respectively with two interior spiral grooves 25 and can carry out reciprocal relative slip in interior spiral groove 25, thereby drives cylinder 2 and carries out the rotation of circumferencial direction.

When the piston moves towards the direction of the first control cavity and moves to a terminal position close to the first control cavity, the piston contacts with a horizontal section of the control rod in the first control cavity and drives the control rod to move axially, so that a vertical section of the control rod and the inner spiral groove slide relatively, the cylinder barrel is driven to rotate in the circumferential direction, the flow area between the first through hole and the port A is reduced, and the flow area between the second through hole and the port B is increased. Meanwhile, the cylinder barrel rotates to drive the control rod in the second control chamber to axially move along the direction of the first control chamber, so that the horizontal section of the control rod extends into the second control chamber.

When the piston moves towards the direction of the second control cavity and moves to a terminal position close to the second control cavity, the piston contacts with a horizontal section of the control rod in the second control cavity and drives the control rod to move axially, so that a vertical section of the control rod and the inner spiral groove slide relatively, the cylinder barrel is driven to rotate in the circumferential direction, the flow area between the second through hole and the port B is reduced, and the flow area between the first through hole and the port A is increased. Meanwhile, the cylinder barrel rotates to drive the control rod in the first control chamber to axially move along the direction of the second control chamber, so that the horizontal section of the control rod extends into the first control chamber.

At the moment, when the piston moves to the terminal positions of the first control cavity and the second control cavity, the control rod drives the cylinder barrel to rotate in the circumferential direction relative to the cylinder body, so that the synchronous adjustment of the flow area between the first through hole and the port A and the synchronous adjustment of the flow area between the second through hole and the port B can be realized, the adjustment of the medium backflow speed in the first control cavity and the second control cavity is realized, and the deceleration buffer effect on the piston is realized.

Referring to fig. 1, a guide hole 11 and a guide groove 12 are formed in the cylinder 1 for fixing a horizontal section and a vertical section of the control rod 4, respectively, so that the control rod can perform an axial reciprocating linear motion. In other embodiments, the guide hole and the horizontal section of the control rod can be designed into a polygonal cross-sectional shape directly, so that the arrangement and use of the guide groove are omitted, and the control rod can perform axial reciprocating linear motion.

In this embodiment, although the control rod is used to drive the cylinder to rotate in the circumferential direction, the flow area between the first through hole and the port a and the flow area between the second through hole and the port B are adjusted. However, in other embodiments, it is also possible to completely implement the adjustment of the flow area between the first through hole and the port a and the flow area between the second through hole and the port B in other manners, for example, the cylinder may be designed to be similar to a slide valve structure, and the two control rods drive the cylinder to perform the axial reciprocating linear movement, so as to control the change of the corresponding relationship between the first through hole and the port a and the change of the corresponding relationship between the second through hole and the port B, and implement the adjustment of the flow area between the first through hole and the port a and the flow area between the second through hole and the port B.

In addition, the reciprocating motion of the cylinder barrel can be completed even in an auxiliary electric control mode. For example, a displacement sensor is provided at the end of the axial reciprocating movement of the piston, and the motor-driven cylinder is controlled to perform reciprocating rotation in the circumferential direction or reciprocating movement in the axial direction by detecting the moving position of the piston by the displacement sensor, thereby adjusting the flow area between the first through hole and the port a and the flow area between the second through hole and the port B.

As shown in fig. 1 and 3, the cylinder 1 is provided with a first annular groove 131, a first U-shaped groove 141, a first oil passage 151, a second annular groove 132, a second U-shaped groove 142, and a second oil passage 152. Wherein, the first annular groove 131 and the second annular groove 132 are respectively positioned on the inner surfaces of the two ends of the cylinder body 1, the first U-shaped groove 141 communicates the first annular groove 131 with the port A, and the second U-shaped groove 142 communicates the second annular groove 132 with the port B. At this time, the first through hole 21 communicates with the port a through the first U-shaped groove 141, and the second through hole 22 communicates with the port B through the second U-shaped groove 142.

When the cylinder 2 rotates in the circumferential direction relative to the cylinder 1, and the flow area between the first through hole 21 and the first U-shaped groove 141 is reduced to the closing process, the flow area between the second through hole 22 and the second U-shaped groove 142 is gradually increased to the maximum, and the first oil passage 151 communicates the port a with the first control chamber 23. Therefore, after the first through hole and the port A are completely closed, the medium at the port A can be drained to the first control cavity again by virtue of the first oil path so as to drive the piston to move towards the direction of the second control cavity, and the medium in the second control cavity directly flows to the port B through the second through hole and the second U-shaped groove and is drained.

Similarly, when the cylinder tube 2 rotates in the circumferential direction with respect to the cylinder block 1, and the flow area between the second through hole 22 and the second U-shaped groove 142 decreases to the closing state, the flow area between the first through hole 21 and the first U-shaped groove 141 gradually increases to the maximum, and the second oil passage 152 communicates the port B with the second control chamber 24. Therefore, after the second through hole and the port B are completely closed, the medium at the port B can be drained to the second control cavity again by virtue of the second oil path so as to drive the piston to move towards the first control cavity, and the medium in the first control cavity directly flows to the port A to be discharged through the first through hole and the first U-shaped groove in the process.

As shown in fig. 1, the first oil passage 151 and the second oil passage 152 are both provided in the cylinder block 1, and the first check valve 51 is provided in the first oil passage 151 and the second check valve 52 is provided in the second oil passage 152. Wherein the inlet of the first check valve 51 is in communication with the first annular groove 131 and the outlet of the first check valve 51 is in communication with the first control chamber 23; the inlet of the second check valve 52 is in communication with the second annular groove 132 and the outlet of the second check valve 52 is in communication with the second control chamber 24.

Therefore, on-off control of the oil way can be achieved by means of the one-way valve, namely, in the process of discharging media in the control cavity, the corresponding oil way keeps in a disconnected state, all the media are discharged through the through holes with the same flow area gradually reduced, the deceleration buffer effect of the piston is guaranteed, otherwise, when the piston moves reversely, the media can be reintroduced into the corresponding control cavity by means of the oil way to drive the piston to move, and the piston can effectively and smoothly reciprocate. In other embodiments, the oil passage may be provided as a cylinder section and a cylinder section, and the cylinder section may be rotated to a final position relative to the cylinder to form a communication relationship, thereby eliminating the need for arranging the check valve.

In addition, in the present embodiment, the first oil path and the second oil path are respectively communicated with the port a and the port B through the first annular groove and the second annular groove, and similarly, in other embodiments, the opening position and the shape of the oil path may be adjusted, so that the first oil path is directly communicated with the port a, and the second oil path is directly communicated with the port B, thereby omitting the opening of the first annular groove and the second annular groove.

As shown in fig. 1 to 5, in the present embodiment, the ports a and B on the cylinder block 1 are coaxially arranged, and the first through holes 21 and the second through holes 22 are alternately arranged in the circumferential direction, so that the on-off relationship between the first through holes 21 and the ports a and between the second through holes 22 and the ports B is switched during the rotation of the cylinder tube 2 in the circumferential direction relative to the cylinder block 1. Similarly, in other embodiments, the ports a and B on the cylinder 1 may be alternately arranged in the circumferential direction, and the first through holes 21 and the second through holes 22 may be coaxially arranged, or the on-off relationship between the first through holes 21 and the ports a and between the second through holes 22 and the ports B may be switched during the rotation of the cylinder 2 in the circumferential direction relative to the cylinder 1.

In addition, in this embodiment, the first through holes and the second through holes are arranged in a staggered manner along the circumferential direction and are arranged correspondingly to the radian of the inner spiral groove in the end part of the cylinder barrel along the circumferential direction, so that when the control cavity drives the cylinder barrel to rotate through the inner spiral groove, the switching between the maximum flow area and the complete closing can be accurately completed between the first through holes and the port A and between the second through holes and the port B, and the deceleration buffer effect on the piston is ensured.

In addition, as shown in fig. 1, the piston 1 of the present embodiment adopts a step structure, that is, after the piston moves to the terminal position of the first control chamber and the terminal position of the second control chamber, the first control chamber and the second control chamber still exist. Therefore, the high-pressure medium led through the oil path can quickly form and establish driving force for the piston, the response speed of the piston in the reverse motion is improved, and the dynamic performance of the whole hydraulic cylinder is improved.

Referring to fig. 1, in the hydraulic cylinder of the present embodiment, a positioning assembly 6 is further provided. The positioning assembly 6 is located between the cylinder body 1 and the cylinder barrel 2 and used for positioning the rotation position of the cylinder barrel 2 relative to the cylinder body 1, so that the accurate stability of the position of the cylinder barrel 2 in the movement process of the piston 1 is ensured.

Preferably, as shown in fig. 6, in the present embodiment, the positioning assembly 6 includes a positioning hole 61, a positioning spring 62, a positioning ball 63 and a positioning groove 64. Wherein, the locating hole 61 is opened on the cylinder 1, and the locating spring 62 and the locating ball 63 are located in the locating hole 61, and the locating groove 64 is located on the cylinder 2 and on the same circumference corresponding to the locating hole 61. Thus, in the reciprocating rotation process of the cylinder barrel 2, the positioning ball 63 directly contacts with the end face of the cylinder barrel 1 to compress the positioning spring 62, so that the positioning spring is kept in the positioning hole 61, after the cylinder barrel 2 rotates in place, the positioning groove 64 and the positioning hole 61 are located on the same axis, one end of the positioning ball 63 is located in the positioning hole 61, and the other end of the positioning ball extends out of the positioning groove 64, so that the position fixing between the cylinder barrel 1 and the cylinder barrel 2 is completed, and the positioning of the cylinder barrel 2 is realized.

Similarly, in other embodiments, the positioning hole can be disposed on the cylinder, and the positioning groove can be disposed on the cylinder, even with other structures, such as a positioning pin, to fix the position of the cylinder.

In addition, as shown in fig. 1, in the present embodiment, the cylinder body 1 is designed in a split structure, and is composed of a body portion and cover plates at two ends, and the two cover plates are axially and fixedly connected with the body portion by bolts. Like this, not only be convenient for to whole cylinder body manufacturing, reduce the processing degree of difficulty and cost, convenient to detach improves the convenience of packaging efficiency and maintenance moreover.

Referring to fig. 1 and 2, when the hydraulic cylinder of the present embodiment works, the port a and the port B are respectively connected to an external pipeline, and the specific working process is as follows:

when the piston rod 31 performs the recovery operation, the medium at the B port flows into the second control chamber 24 through the second U-shaped groove 142, the second annular groove 132, and the second oil passage 152, the medium in the first control chamber 23 flows into the a port through the first through hole 21 and the first U-shaped groove 141 and is discharged, and the piston 3 moves toward the first control chamber 23 under the pressure of the medium between the first control chamber 23 and the second control chamber 24. When the piston 3 moves to contact with the horizontal section of the control rod 4 in the first control cavity 23, the control rod 4 is driven to move axially, so that the vertical section of the control rod 4 and the corresponding inner spiral groove 25 slide relatively, and the cylinder barrel 2 is driven to rotate in the circumferential direction, the flow area between the first through hole 21 and the first U-shaped groove 141 is reduced, the outflow speed of a medium in the first control cavity 23 is reduced, and a buffer effect is reduced on the piston 1 until the piston 1 stops moving.

Meanwhile, in the rotation process of the cylinder 2 relative to the cylinder 1, the flow area between the second through hole 22 and the second U-shaped groove 142 is gradually increased to the maximum state, and the control rod 4 in the second control chamber 22 is driven to axially move along the direction of the first control chamber 21, so that the horizontal section of the control rod 4 extends into the second control chamber 22.

When the piston rod 31 extends, the medium at the port a flows into the first control chamber 23 through the first U-shaped groove 142, the first annular groove 131 and the first oil path 151, the medium in the second control chamber 24 flows into the port B through the second through hole 22 and the second U-shaped groove 142 and is discharged, and the piston 3 moves towards the second control chamber 24 under the pressure of the medium between the first control chamber 23 and the second control chamber 24. When the piston 3 moves to contact with the horizontal section of the control rod 4 in the second control cavity 24, the control rod 4 is driven to move axially, so that the vertical section of the control rod 4 and the corresponding inner spiral groove 25 form relative sliding, and then the cylinder barrel 2 is driven to rotate in the circumferential direction, the flow area between the second through hole 22 and the second U-shaped groove 142 is reduced, the outflow speed of a medium in the second control cavity 24 is reduced, and a reduction buffering effect is formed on the piston 1 until the piston 1 stops moving.

Meanwhile, in the rotation process of the cylinder 2 relative to the cylinder 1, the flow area between the first through hole 21 and the first U-shaped groove 141 is gradually increased to the maximum state, and the control rod 4 in the first control chamber 21 is driven to axially move along the direction of the second control chamber 22, so that the horizontal section of the control rod 4 extends into the first control chamber 21.

Claims

1. A hydraulic cylinder is characterized by comprising a cylinder body, a cylinder barrel and a piston; the cylinder body is provided with an A port and a B port, the cylinder barrel is provided with a first through hole and a second through hole, and the cylinder barrel is positioned in the cylinder body and can reciprocate relative to the cylinder body; the piston is positioned in the cylinder barrel, and the interior of the cylinder barrel is divided into a first control cavity and a second control cavity which are not communicated with each other; a piston rod is arranged at one end of the piston, and the piston rod penetrates through the first control cavity and extends out of the cylinder body; the first control cavity is communicated with the port A through the first through hole, the second control cavity is communicated with the port B through the second through hole, and the piston reciprocates relative to the cylinder body under the action of medium pressure between the first control cavity and the second control cavity;

when the piston moves to the terminal position of the first control cavity, the cylinder barrel moves relative to the cylinder body, so that the flow area between the first through hole and the port A is reduced, and the speed of the medium in the first control cavity flowing back to the port A through the first through hole is reduced; when the piston moves to the terminal position of the second control cavity, the cylinder barrel moves relative to the cylinder body, so that the flow area between the second through hole and the port B is reduced, and the speed of the medium in the second control cavity flowing back to the port B through the second through hole is reduced;

the cylinder barrel is rotationally connected with the cylinder body in the circumferential direction; when the piston moves to the terminal position of the first control cavity, the cylinder barrel rotates relative to the cylinder body in the circumferential direction, so that the flow area between the first through hole and the port A is reduced; when the piston moves to the terminal position of the second control cavity, the cylinder barrel rotates relative to the cylinder body in the circumferential direction, so that the flow area between the second through hole and the port B is reduced;

the cylinder body is provided with a first annular groove, a first U-shaped groove, a first oil way, a second annular groove, a second U-shaped groove and a second oil way; the first annular groove and the second annular groove are respectively positioned on the inner surfaces of two ends of the cylinder body, the first U-shaped groove is used for communicating the first annular groove with the port A, and the second U-shaped groove is used for communicating the second annular groove with the port B; the first through hole is communicated with the port A through the first U-shaped groove, and the second through hole is communicated with the port B through the second U-shaped groove; when the piston moves to the terminal position of the first control cavity, the cylinder barrel rotates relative to the cylinder body in the circumferential direction, so that the flow area between the first through hole and the first U-shaped groove is reduced, the flow area between the second through hole and the second U-shaped groove is increased, and the port A and the first control cavity are communicated through the first oil path; when the piston moves to the terminal position of the second control cavity, the cylinder barrel rotates in the circumferential direction relative to the cylinder body, so that the flow area between the second through hole and the second U-shaped groove is reduced, the flow area between the first through hole and the first U-shaped groove is increased, and the second oil path enables the port B to be communicated with the second control cavity;

the first oil way and the second oil way are uniformly distributed on the cylinder body, a first one-way valve is arranged on the first oil way, and a second one-way valve is arranged on the second oil way; an inlet of the first one-way valve is communicated with the first annular groove, and an outlet of the first one-way valve is communicated with the first control cavity; an inlet of the second one-way valve is in communication with the second annular groove and an outlet of the second one-way valve is in communication with the second control chamber.

2. The hydraulic cylinder according to claim 1, wherein the hydraulic cylinder is provided with two control rods, and two ends of the cylinder barrel are respectively provided with an inner spiral groove; the two control rods are respectively positioned at the terminal position of the first control cavity and the terminal position of the second control cavity, the horizontal sections of the two control rods are axially opposite to the piston and can perform axial reciprocating linear motion, and the vertical sections of the two control rods are respectively connected with the two inner spiral grooves and can perform reciprocating sliding in the inner spiral grooves.

3. The hydraulic cylinder of claim 2, wherein the cylinder body is provided with a guide groove; the guide groove is axially arranged, and the vertical section of the control rod is positioned in the guide groove to perform axial reciprocating linear motion.

4. The hydraulic cylinder of claim 1, further comprising a positioning assembly; the positioning assembly is located between the cylinder body and the cylinder barrel and used for positioning the position of the cylinder barrel, which moves to and fro relative to the cylinder body.

5. The hydraulic cylinder of claim 4, wherein the positioning assembly comprises a positioning hole, a positioning spring, a positioning ball and a positioning groove; the positioning hole and the positioning groove are respectively positioned on the cylinder body and the cylinder barrel, and the positioning spring and the positioning ball are positioned in the positioning hole; in the reciprocating motion process of the cylinder barrel, the positioning ball compresses the positioning spring and is kept in the positioning hole, after the cylinder barrel moves in place, one end of the positioning ball is located in the positioning hole, and the other end of the positioning ball extends out of the positioning groove.

6. The hydraulic cylinder according to any one of claims 1 to 5, wherein the cylinder body has a split structure, and two ends of the cylinder body have a detachable cover plate structure.

7. Hydraulic cylinder according to any one of claims 1 to 5, characterized in that the piston is of stepped construction, so that the first control chamber and the second control chamber are always present.