Rams buffer device

Abstract

The utility model relates to an oil cylinder buffer device belongs to fluid pressure executing mechanism technical field, the utility model discloses an oil cylinder in the operation process, piston ring only plays the supporting role in partial time period, basically will not be subjected to the pressure action of oil, is in the free state, and the outer peripheral wall of piston ring and the inner peripheral surface of cylinder barrel have the clearance, and piston ring does not play the sealing effect, only when the buffer mechanism works, piston ring will be under the action of oil pressure and the side wall of one side of annular groove of cylinder barrel inner wall close, thereby forms the seal, the utility model not only can realize reliable buffering effect, and can reduce the abrasion of piston ring.

Description

Technical Field

[0001] This utility model relates to a hydraulic cylinder buffer device, belonging to the technical field of fluid pressure actuators. Background Technology

[0002] Hydraulic cylinders, as actuators that convert hydraulic energy into mechanical energy, are widely used in various industrial fields. In traditional hydraulic cylinders, when the piston reaches the end of its stroke, due to the large flow rate and high speed, the piston undergoes a mechanical collision with the guide sleeve or cylinder bottom, generating significant impact force and noise. This is particularly noticeable under high pressure and high flow conditions. This impact force can severely affect the cylinder itself and even the entire hydraulic system. For example, long-term, repeated rigid impacts can cause fatigue damage, loosening, or even breakage of cylinder parts, welds, and connected components, shortening the service life of the cylinder and hydraulic system. A sudden stop of the piston can cause an instantaneous interruption of oil flow, creating pressure peaks in the oil circuit, potentially damaging hydraulic pumps, hydraulic valves, and related sealing components. Strong impact forces can also cause severe cylinder vibration, producing harsh noise and deteriorating the working environment. To overcome these problems, it is necessary to reduce the piston's speed at the end of its stroke, i.e., an end-stroke buffer function is required.

[0003] For example, Chinese patent document CN219691884U discloses a hydraulic cylinder buffer structure, including: a cylinder with two oil inlets on its side, end caps and cylinder bottoms installed at both ends of the cylinder, a piston placed in the cylinder, a piston rod connected to the piston at one end and extending out of the end cap at the other end, a rectangular sealing ring disposed between the outer side of the piston and the inner side of the cylinder, and two buffer mechanisms disposed on both sides of the rectangular sealing ring; the buffer mechanism includes: an oil ring groove disposed on the outer side of the piston, a damping hole with one end communicating with one end of the piston, and connecting holes with both ends corresponding to the bottom surface of the oil ring groove and the other end of the damping hole, wherein the size of the oil inlet along the axial direction of the cylinder is greater than the distance between one end of the piston and the side of the oil ring groove near the piston. The hydraulic cylinder buffer mechanism further includes: two annular grooves located on the outer side of the piston, and two piston rings located between the outer side of the piston and the inner side of the cylinder, each corresponding to one of the two annular grooves; the two annular grooves are located on the outer sides of the opposite outer edges of the two oil passage grooves; the cross-sectional shape of the annular grooves is rectangular. When the hydraulic cylinder buffer structure is in operation, when the piston moves close to the cylinder bottom, the rodless chamber and an oil passage are separated by a piston ring and are not connected. The hydraulic oil in the rodless chamber passes through the damping hole, connecting hole, and oil passage groove of a buffer mechanism, and is discharged from the oil passage, reducing the piston's momentum and buffering it to prevent the piston from colliding with the cylinder bottom and causing noise. When the piston rod extends and starts, hydraulic oil enters the rodless chamber from the oil passage through the oil passage groove, connecting hole, and damping hole of a buffer mechanism, causing the piston to move towards the end cover. When the rodless chamber is connected to an oil passage, hydraulic oil directly enters the rodless chamber from one oil passage, accelerating the piston towards the end cover. In this design, when the piston moves close to the end cap, the rod chamber and the oil port are separated by another piston ring, preventing communication. Hydraulic oil in the rod chamber flows through the damping hole, connecting hole, and oil ring groove of another buffer mechanism, exiting through the other oil port. This reduces the piston's momentum and buffers the flow, preventing collisions between the piston and the end cap that could cause noise. When the piston rod retracts and starts moving, hydraulic oil enters the rod chamber from the other oil port through the oil ring groove, connecting hole, and damping hole of the other buffer mechanism, causing the piston to move towards the bottom of the cylinder. Once the rod chamber is connected to the other oil port, hydraulic oil flows directly into the other rod chamber, accelerating the piston towards the bottom of the cylinder. In this design, both piston rings are directly fixed within the annular groove on the outer side of the piston, with no gaps between the piston rings and the side and bottom walls of the annular groove. The piston rings are a fixed structure, making their outer surface prone to wear during cylinder operation, thus affecting the cylinder's buffering performance and operational stability. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a hydraulic cylinder buffer device that can reduce the wear on the outer surface of the piston ring.

[0005] The technical solution adopted by this utility model to solve its technical problem is as follows: a hydraulic cylinder buffer device, including a cylinder barrel, a piston, a piston rod, a guide sleeve, and a cylinder bottom. The cylinder bottom is fixedly assembled to one end of the cylinder barrel, and the guide sleeve is fixedly assembled to the other end of the cylinder barrel to form the hydraulic cylinder cavity. The inner circumferential surface of the guide sleeve is sealed to the outer circumferential surface of the piston rod. One end of the piston rod extending into the cylinder barrel is fixedly connected to the piston. The piston divides the hydraulic cylinder cavity into a rodless cavity and a rod cavity. The side wall of the cylinder barrel is provided with two oil passage holes spaced apart along its axial direction. The outer side wall of the cylinder barrel is fixedly provided with oil ports corresponding to the oil passage holes. A main sealing ring is provided at the middle position of the outer circumferential surface of the piston to form a sealing fit with the inner circumferential surface of the cylinder barrel. Buffer mechanisms are provided on both sides of the main sealing ring of the piston. The buffer mechanism includes an oil passage blind hole, a throttling hole, an oil passage ring groove, and a piston ring. The oil passage blind hole is correspondingly provided on the end face of the piston. The oil passage ring groove and the piston ring are correspondingly provided on the outer circumferential surface of the piston, and the piston ring is located on the side of the oil passage ring groove closer to the piston end face. The outer circumferential surface of the piston is provided with... The annular groove of the piston ring is matched with the oil passage blind hole. The inner end of the oil passage blind hole is connected to the corresponding oil passage ring groove through the throttling hole. The width dimension of the piston ring along the cylinder axial direction is smaller than the width dimension of the oil passage hole along the cylinder axial direction. When the piston moves to the end face of the cylinder cavity, the oil passage hole is located in the gap area between the main seal ring and the piston ring. The piston ring includes a piston ring body with a break. The piston ring body is connected at the break by a sliding engagement between a locking protrusion and a locking groove. The relative sliding direction of the locking protrusion and the locking groove is... Corresponding to the circumferential direction of the piston ring, the axial end face of the piston ring has an oil passage gap relative to the side wall of the annular groove. In its natural state, the inner circumferential wall of the piston ring has a gap with the bottom wall of the annular groove, and the outer circumferential wall has a gap with the inner circumferential surface of the cylinder. When the oil passage hole is located in the interval area between the main seal ring and the piston ring, the piston ring closest to the oil passage hole can be pressed tightly against one side wall of the annular groove due to the oil pressure, and generate elastic deformation so that the outer circumferential surface of the piston ring contacts the inner circumferential surface of the cylinder.

[0006] A further preferred embodiment is that: the cross-section of the annular groove is rectangular; the radial cross-section of the piston ring body is rectangular; one side of the engaging protrusion is flush with the inner circular surface of the piston ring; one end face of the engaging protrusion is flush with the axial end face of the piston ring; and the width of the engaging protrusion along the cylinder axial direction is smaller than the width of the piston ring body along the cylinder axial direction, and the thickness of the engaging protrusion along the cylinder radial direction is smaller than the thickness of the piston ring body along the cylinder radial direction. The radial cross-section of the overall assembly after the engaging protrusion and engaging groove are engaged is consistent with the radial cross-section of the piston ring body. That is, the projection of the overall assembly after the engaging protrusion and engaging groove are engaged in the cylinder radial cross-section forms a Z-shaped splice seam, and the projection in the cylinder axial cross-section also forms a Z-shaped splice seam.

[0007] A further preferred option is that the piston rings are made of ductile iron.

[0008] A further preferred option is that the main sealing ring is a rectangular sealing ring.

[0009] A further preferred embodiment is that the cross-section of both the oil passage blind hole and the throttle hole are circular, the axis of the oil passage blind hole is set along the cylinder axial direction, and the axis of the throttle hole is set along the cylinder radial direction.

[0010] A further preferred embodiment is that the oil port is welded and fixed to the outer wall of the cylinder.

[0011] A further preferred embodiment is that the piston rings are detachably fixed in the annular groove, and the guide sleeve is detachably fixed on the cylinder.

[0012] A further preferred embodiment is that the guide sleeve is pressed and fixed onto the cylinder by the end cap and bolts.

[0013] The piston ring closer to the cylinder bottom is designated as the first piston ring, and the piston ring closer to the guide sleeve is designated as the second piston ring; the oil passage closer to the cylinder bottom is designated as the first oil passage, and the oil passage closer to the guide sleeve is designated as the second oil passage.

[0014] The working principle of this invention is as follows: When the cylinder retracts, before the two piston rings on the piston pass through the first oil passage, all the hydraulic oil is discharged directly through the first oil passage. Therefore, the piston rings are basically not subjected to oil pressure and are in a free state. There is a gap between the outer circumferential wall of the piston ring and the inner circumferential surface of the cylinder, and the piston ring does not perform a sealing function. At the same time, because its material is ductile iron, its wear resistance and hardness are higher than those of ordinary plastic seals. Furthermore, through its bidirectional Z-shaped splicing seam, the outer diameter of the piston ring is precisely controlled, which can provide good support for the piston and thus protect the main sealing ring on the piston. When the first piston ring on the piston passes through the first oil passage, the oil in the rodless chamber cannot be discharged from the first oil passage in time. This exerts pressure on the first piston ring, causing it to press tightly against the inner wall of the cylinder and the side wall of the annular groove closest to the first oil passage, thus forming a seal. This prevents oil from the rodless chamber from flowing into the first oil passage from the outer periphery of the piston. The oil can only flow from the oil passage blind hole through the throttle hole to the first oil passage. The diameter of the throttle hole is generally very small. When the oil cannot be discharged in time, back pressure is formed, thereby reducing the piston's running speed and achieving a buffering effect. The piston is also equipped with an oil passage ring groove that communicates with the throttle hole, ensuring that the oil flowing out of the throttle hole can enter the first oil passage in time throughout the entire buffering process.

[0015] Similarly, when the cylinder extends, before the two piston rings on the piston pass through the second oil passage, all the hydraulic oil will be discharged directly through the second oil passage. Therefore, the piston rings are basically not subjected to oil pressure and are in a free state. There is a gap between the outer circumferential wall of the piston ring and the inner circumferential surface of the cylinder, and the piston ring does not perform a sealing function. At the same time, because its material is ductile iron, its wear resistance and hardness are higher than those of ordinary plastic seals. With its bidirectional Z-shaped splicing seam, the outer diameter of the piston ring can be precisely controlled, which can provide good support for the piston and protect the main seal ring on the piston. When the second piston ring on the piston passes through the second oil passage, the oil in the rod chamber cannot be discharged from the second oil passage in time, thus putting pressure on the second piston ring. Under the pressure, the second piston ring will press tightly against the inner wall of the cylinder and the side wall of the annular groove near the second oil passage, thus forming a seal and preventing the oil in the rod chamber from flowing into the second oil passage from the outer circumferential area of ​​the piston. The oil can only flow to the second oil passage through the oil blind hole and the throttle hole. The diameter of the throttling orifice is generally very small. When the oil cannot be discharged in time, back pressure will be formed, thereby reducing the piston's running speed and achieving a buffering effect. The piston is also equipped with an oil passage groove that communicates with the throttling orifice, which ensures that the oil flowing out of the throttling orifice can enter the second oil passage in time throughout the entire buffering process.

[0016] The beneficial effects of this invention are as follows: During the operation of the hydraulic cylinder, the piston ring only plays a supporting role during certain periods and is basically not subjected to the pressure of the oil, remaining in a free state. There is a gap between the outer circumferential wall of the piston ring and the inner circumferential surface of the cylinder, and the piston ring does not provide a sealing function. Only when the buffer mechanism is working will the piston ring, under the pressure of the oil, adhere tightly to the inner wall of the cylinder and one side wall of the annular groove, thus forming a seal. This invention not only achieves a reliable buffering effect but also reduces piston ring wear. The piston ring is made of ductile iron, which has higher wear resistance and hardness than ordinary plastic seals, allowing it to pass through the oil passage of the hydraulic cylinder more easily without being scratched. Through the bidirectional Z-shaped splicing seam design, the piston ring can be more precisely fitted, thereby controlling the amount of piston ring deformation and providing better sealing of the oil. Both the piston ring and the guide sleeve are removable, making it easy to replace and repair the piston ring after damage without causing significant damage to the inner wall of the cylinder, thus preventing the entire hydraulic cylinder from being scrapped. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the hydraulic cylinder of this utility model; Figure 2 This is a schematic diagram showing the position where the hydraulic cylinder begins to buffer during retraction in this utility model. Figure 3 This is a schematic diagram showing the position where the hydraulic cylinder begins to buffer when it extends, according to this utility model. Figure 4 This is a schematic diagram of the piston ring under pressure sealing according to this utility model; Figure 5 yes Figure 4 An enlarged structural diagram of region A; Figure 6 This is a schematic diagram of the piston ring structure of this utility model; Figure 7 yes Figure 6 BB cross-sectional view.

[0018] The components in the diagram are labeled as follows: 1-Cylinder, 2-Piston ring, 3-Oil port, 4-Piston, 5-Piston rod, 6-Guide sleeve, 7-Cylinder bottom, 8-Oil passage hole, 9-Oil blind hole, 10-Throttle hole, 11-Oil ring groove, 12-Annular groove, 13-Engaging protrusion, 14-Cylinder inner wall. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] like Figures 1 to 5As shown, the main structure of this utility model is the same as that of existing conventional technology, including a cylinder 1, a piston 4, a piston rod 5, a guide sleeve 6, and a cylinder bottom 7. The cylinder bottom 7 is fixedly assembled to one end of the cylinder 1, and the guide sleeve 6 is fixedly assembled to the other end of the cylinder 1 to form the inner cavity of the hydraulic cylinder. That is, the cylinder 1, the guide sleeve 6, and the cylinder bottom 7 form a relatively closed inner cavity of the hydraulic cylinder, which generally only has the necessary piston rod through hole and oil inlet and outlet channels. The inner circumferential surface of the guide sleeve 6 is sealed to the outer circumferential surface of the piston rod 5. The end of the piston rod 5 that extends into the cylinder 1 is fixedly connected to the piston 4. The piston 4 divides the inner cavity of the hydraulic cylinder into a rodless cavity and a rod cavity. The side wall of the cylinder 1 is provided with a groove along the... The piston 4 has two axially spaced oil passages 8. The outer wall of the cylinder 1 is fixedly provided with oil ports 3 corresponding to the oil passages 8. A main sealing ring (not shown in the figure) is provided at the center of the outer circumferential surface of the piston 4 to form a sealing fit with the inner circumferential surface of the cylinder 1. The piston 4 has buffer mechanisms on both sides of the main sealing ring. The buffer mechanisms include an oil passage blind hole 9, a throttle hole 10, an oil passage ring groove 11, and a piston ring 2. The oil passage blind hole 9 is correspondingly located on the end face of the piston 4. The oil passage ring groove 11 and the piston ring 2 are correspondingly located on the outer circumferential surface of the piston 4, with the piston ring 2 located on the side of the oil passage ring groove 11 closest to the end face of the piston 4. The outer circumferential surface of the piston 4... The piston ring 2 has an annular groove 12 that mates with the piston ring 2. The inner end of the oil passage blind hole 9 is connected to the corresponding oil passage ring groove 11 through the throttle hole 10. The width dimension of the piston ring 2 along the axial direction of the cylinder 1 is smaller than the width dimension of the oil passage hole 8 along the axial direction of the cylinder 1. When the piston 4 moves to the end face of the cylinder cavity, the oil passage hole 8 is located in the gap area between the main sealing ring and the piston ring 2. The piston ring 2 includes a piston ring body with a break. The piston ring body is connected to the break by a locking protrusion 13 and a locking groove through a sliding engagement. The relative sliding direction of the locking protrusion 13 and the locking groove corresponds to the circumferential direction of the piston ring 2. The axial end face of the piston ring 2 has an oil passage gap relative to the side wall of the annular groove 12 (that is, the width dimension of the piston ring 2 along the axial direction of the cylinder 1 is smaller than the width dimension of the annular groove 12 along the axial direction of the cylinder 1). In its natural state, the inner peripheral wall of the piston ring 2 has a gap with the bottom wall of the annular groove 12, and the outer peripheral wall has a gap with the inner peripheral surface of the cylinder 1. When the oil passage hole 8 is located in the interval area between the main sealing ring and the piston ring 2, the piston ring 2 closest to the oil passage hole 8 can be pressed tightly against one side wall of the annular groove 12 due to the oil pressure, and generate elastic deformation so that the outer peripheral surface of the piston ring 2 contacts the inner peripheral surface of the cylinder 1.

[0021] For ease of understanding, the piston ring 2 near the cylinder bottom 7 is designated as the first piston ring, and the piston ring 2 near the guide sleeve 6 is designated as the second piston ring; the oil passage 8 near the cylinder bottom 7 is designated as the first oil passage, and the oil passage 8 near the guide sleeve 6 is designated as the second oil passage. In implementation, if... Figure 2As shown, when the cylinder retracts, before the two piston rings 2 on the piston 4 have passed through the first oil passage, the hydraulic oil will be discharged directly through the first oil passage. Therefore, the piston rings 2 are basically not subjected to the pressure of the oil and are in a free state. There is a gap between the outer circumferential wall of the piston ring 2 and the inner circumferential surface of the cylinder 1. The piston ring 2 does not perform a sealing function, but only provides support for the piston 4 to protect the main sealing ring on the piston 4. After the first piston ring on the piston 4 passes through the first oil passage, the oil in the rodless chamber cannot be discharged from the first oil passage in time, thus exerting pressure on the first piston ring. Under the pressure, the first piston ring will press tightly against the inner circumferential surface of the cylinder 1 and the side wall of the annular groove 12 near the first oil passage, thus forming a seal and preventing the oil in the rodless chamber from flowing into the first oil passage from the outer circumferential area of ​​the piston 4. The oil can only flow from the oil blind hole 9 through the throttle hole 10 to the first oil passage. The diameter of the throttle orifice 10 is generally very small. When the oil cannot be discharged in time, back pressure will be formed, thereby reducing the running speed of the piston 4 and achieving a buffering effect. The piston 4 is also provided with an oil passage groove 11 that communicates with the throttle orifice 10, which can ensure that the oil flowing out of the throttle orifice 10 can enter the first oil passage in time during the entire buffering process.

[0022] Similarly, such as Figure 3 As shown, when the cylinder extends, before the two piston rings 2 on the piston 4 have passed through the second oil passage, the hydraulic oil will be discharged directly through the second oil passage. Therefore, the piston ring 2 is basically not subjected to the pressure of the oil and is in a free state. There is a gap between the outer circumferential wall of the piston ring 2 and the inner circumferential surface of the cylinder 1, and the piston ring 2 does not perform a sealing function. It only provides support for the piston 4 to protect the main sealing ring on the piston 4. When the second piston ring on the piston 4 passes through the second oil passage, the oil in the rod chamber cannot be discharged from the second oil passage in time, thus putting pressure on the second piston ring. Under the pressure, the second piston ring will press tightly against the inner circumferential surface of the cylinder 1 and the side wall of the annular groove 12 near the second oil passage, thus forming a seal and preventing the oil in the rod chamber from flowing into the second oil passage from the outer circumferential area of ​​the piston 4. The oil can only flow from the oil blind hole 9 through the throttle hole 10 to the second oil passage. The diameter of the throttle orifice 10 is generally very small. When the oil cannot be discharged in time, back pressure will be formed, thereby reducing the running speed of the piston 4 and achieving a buffering effect. The piston 4 is also provided with an oil passage groove 11 that communicates with the throttle orifice 10, which can ensure that the oil flowing out of the throttle orifice 10 can enter the second oil passage in time during the entire buffering process.

[0023] Taking the hydraulic cylinder as an example, with the cylinder bottom 7 located at the left end of the cylinder and the cylinder retraction buffering process, please refer to [reference needed]. Figure 4 and Figure 5The specific working principle of the piston ring 2 under pressure sealing is as follows: After the left piston ring 2 passes through the oil passage 8, the right end face of the left piston ring 2 will be pressed against the right side of the annular groove 12 to form a seal after being subjected to the pressure of the oil. The left end face of the piston ring 2 and the left side of the annular groove 12 can form an oil passage gap, and the oil can fill the bottom area of ​​the annular groove 12. The pressure of the oil can simultaneously cause the piston ring 2 to expand and deform outward (the engaging protrusion 13 and the engaging groove slide relative to each other in the circumferential direction of the piston ring 2). The outer circumferential surface of the piston ring 2 will be pressed against the inner circumferential surface of the cylinder 1 (i.e., the inner wall 14 of the cylinder) to form a seal, thereby preventing the oil from flowing into the oil port 3 from this side. The oil can only flow to the oil port 3 from the oil passage blind hole 9 through the throttle hole 10.

[0024] To enhance structural reliability, in a preferred embodiment, the annular groove 12 has a rectangular cross-section, the piston ring body has a rectangular radial cross-section, one side of the engaging protrusion 13 is flush with the inner circular surface of the piston ring 2, one end face of the engaging protrusion 13 is flush with the axial end face of the piston ring 2, and the width of the engaging protrusion 13 along the axial direction of the cylinder 1 is smaller than the width of the piston ring body along the axial direction of the cylinder 1, and the thickness of the engaging protrusion 13 along the radial direction of the cylinder 1 is smaller than the thickness of the piston ring body along the radial direction of the cylinder 1. The radial cross-section of the overall assembly after the engaging protrusion 13 and the engaging groove are engaged is consistent with the radial cross-section of the piston ring body. That is, the projection of the overall assembly after the engaging protrusion 13 and the engaging groove onto the radial cross-section of the cylinder 1 forms a Z-shaped splice seam (e.g., ...). Figure 6 As shown), the projection of the axial section of cylinder 1 also forms a Z-shaped splice seam (as shown). Figure 7 (As shown). With the above structural design, the engaging protrusion 13 and the engaging groove have a precise guiding effect. Through the spatial restriction in four directions, the piston ring 2 can be more precisely matched, thereby controlling the elastic deformation of the piston ring 2 and better sealing of the oil when the buffer mechanism is working.

[0025] In a preferred embodiment, the piston ring 2 is made of ductile iron, which has higher wear resistance and hardness than ordinary plastic seals. It can pass through the oil passage 8 of the cylinder more easily without being scratched. At the same time, during the operation of the cylinder, it can provide good support for the piston 4, thereby protecting the main sealing ring on the piston 4.

[0026] For ease of processing, in a preferred embodiment, the cross-section of the oil passage blind hole 9 and the cross-section of the throttle hole 10 are both circular. The axis of the oil passage blind hole 9 is arranged along the axial direction of the cylinder barrel 1, and the axis of the throttle hole 10 is arranged along the radial direction of the cylinder barrel 1.

[0027] To facilitate processing and assembly, in a preferred embodiment, the oil port 3 is welded and fixed to the outer wall of the cylinder barrel 1.

[0028] To facilitate processing and assembly, as well as subsequent maintenance, in a preferred embodiment, the piston ring 2 is detachably fixed within the annular groove 12, and the guide sleeve 6 is detachably fixed to the cylinder 1. Both the piston ring 2 and the guide sleeve 6 are detachable, making replacement and repair easy even if the piston ring 2 is damaged, without causing significant damage to the inner wall of the cylinder 1, thus preventing the entire cylinder from being scrapped.

[0029] To ensure a simple, reliable, and easy-to-assemble structure, in one preferred embodiment, the guide sleeve 6 is fixed to the cylinder 1 by an end cap and bolts. In other embodiments, the guide sleeve 6 may also be fixed using a retaining structure such as a snap ring.

Claims

1. A hydraulic cylinder buffer device, comprising a cylinder (1), a piston (4), a piston rod (5), a guide sleeve (6), and a cylinder bottom (7). The cylinder bottom (7) is fixedly assembled at one end of the cylinder (1), and the guide sleeve (6) is fixedly assembled at the other end of the cylinder (1) to form the hydraulic cylinder cavity. The inner circumferential surface of the guide sleeve (6) is sealed to the outer circumferential surface of the piston rod (5). One end of the piston rod (5) extending into the cylinder (1) is fixedly connected to the piston (4). The piston (4) divides the hydraulic cylinder cavity into a rodless cavity and a rod cavity. The side wall of the cylinder (1) is provided with two oil passage holes (8) spaced apart along its axial direction. The outer side wall of the cylinder (1) is fixedly provided with oil ports (3) corresponding to the oil passage holes (8). The piston (4) is provided with a main sealing ring at the middle position of its outer circumferential surface for forming a sealing fit with the inner circumferential surface of the cylinder (1). The piston (4) is provided with buffers on both sides of the main sealing ring. The mechanism, the buffer mechanism includes an oil passage blind hole (9), a throttle hole (10), an oil passage ring groove (11), and a piston ring (2). The oil passage blind hole (9) is correspondingly disposed on the end face of the piston (4). The oil passage ring groove (11) and the piston ring (2) are correspondingly disposed on the outer circumferential surface of the piston (4), and the piston ring (2) is located on the side of the oil passage ring groove (11) close to the end face of the piston (4). The outer circumferential surface of the piston (4) is provided with an annular groove (12) that cooperates with the piston ring (2). The inner end of the oil passage blind hole (9) is connected to the corresponding oil passage ring groove (11) through the throttle hole (10). The width dimension of the piston ring (2) along the axial direction of the cylinder (1) is smaller than the width dimension of the oil passage hole (8) along the axial direction of the cylinder (1). When the piston (4) moves to the end face of the cylinder cavity, the oil passage hole (8) is located in the interval area between the main sealing ring and the piston ring (2). The characteristic is that: The piston ring (2) includes a piston ring body with a break. The piston ring body is connected to the break by a sliding engagement of a locking protrusion (13) and a locking groove. The relative sliding direction of the locking protrusion (13) and the locking groove corresponds to the circumferential direction of the piston ring (2). The axial end face of the piston ring (2) has an oil passage gap relative to the side wall of the annular groove (12). In its natural state, the inner circumferential wall of the piston ring (2) has a gap with the bottom wall of the annular groove (12), and the outer circumferential wall has a gap with the inner circumferential surface of the cylinder (1). When the oil passage hole (8) is located in the interval area between the main sealing ring and the piston ring (2), the piston ring (2) close to the oil passage hole (8) can be pressed tightly against one side wall of the annular groove (12) due to the oil pressure, and generate elastic deformation so that the outer circumferential surface of the piston ring (2) contacts the inner circumferential surface of the cylinder (1).

2. The hydraulic cylinder buffer device as described in claim 1, characterized in that: The cross-section of the annular groove (12) is rectangular; the radial cross-section of the piston ring body is rectangular; one side of the engaging protrusion (13) is flush with the inner circular surface of the piston ring (2); one end face of the engaging protrusion (13) is flush with the axial end face of the piston ring (2); the width dimension of the engaging protrusion (13) along the axial direction of the cylinder (1) is smaller than the width dimension of the piston ring body along the axial direction of the cylinder (1); the thickness dimension of the engaging protrusion (13) along the radial direction of the cylinder (1) is smaller than the thickness dimension of the piston ring body along the radial direction of the cylinder (1); the radial cross-section of the overall assembly after the engaging protrusion (13) and the engaging groove are engaged is consistent with the radial cross-section of the piston ring body.

3. The hydraulic cylinder buffer device as described in claim 1, characterized in that: The piston ring (2) is made of ductile iron.

4. The hydraulic cylinder buffer device as described in claim 1, characterized in that: The cross-sections of the oil passage blind hole (9) and the throttle hole (10) are both circular. The axis of the oil passage blind hole (9) is set along the axial direction of the cylinder (1), and the axis of the throttle hole (10) is set along the radial direction of the cylinder (1).

5. The hydraulic cylinder buffer device as described in claim 1, characterized in that: The main sealing ring is a rectangular sealing ring.

6. The hydraulic cylinder buffer device as described in claim 1, characterized in that: The oil port (3) is welded and fixed to the outer wall of the cylinder (1).

7. The hydraulic cylinder buffer device as described in claim 1, characterized in that: The cylinder bottom (7) is welded and fixed to the cylinder barrel (1).

8. The hydraulic cylinder buffer device according to any one of claims 1 to 7, characterized in that: The piston ring (2) is detachably fixed in the annular groove (12), and the guide sleeve (6) is detachably fixed on the cylinder (1).

9. The hydraulic cylinder buffer device as described in claim 8, characterized in that: The guide sleeve (6) is pressed and fixed to the cylinder (1) by the end cover and bolts.

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