Oil cylinder device with buffer mechanism and buffer method

Abstract

The present invention discloses an oil cylinder device with a buffer mechanism and a buffer method, wherein the oil cylinder device includes a cylinder having a cavity, a piston rod located in the cylinder, a piston, an oil port and a buffer, wherein the piston divides the cavity of the cylinder into two opposite first sealed spaces and a second sealed space, and the oil port includes at least one through hole arranged on the side wall of the cylinder; the buffer includes a groove body opened on the side wall of the piston and capable of communicating with the first sealed space, a buffer ring arranged in the groove body and abutting against the inner wall of the cylinder, and a notch is arranged on the buffer ring that can respectively communicate with the through hole and the first sealed space. The present invention includes at least the following advantages: through the oil circuit formed by the buffer ring notch, the groove body and the through hole, the flow rate of hydraulic oil flowing out and flowing into the cylinder per unit time is controlled, so as to realize the buffering action of the piston rod, and the structure is ingenious and the coordination is simple.

Description

Technical Field

[0001] The invention relates to the technical field of driving parts, and in particular to an oil cylinder device with a buffer mechanism and a buffer method. Background Art

[0002] The description in this section merely provides background information related to the present disclosure and does not constitute prior art.

[0003] The oil cylinder is a hydraulic actuator that converts hydraulic energy into mechanical energy and performs reciprocating linear motion. During the reciprocating motion, due to the large impact of the hydraulic force, the piston is easily damaged by the collision between the piston and the cylinder body during the extension and retraction movements. The existing hydraulic cylinder is provided with a buffer ring on the piston rod, and a buffer gasket is provided at the rear end of the cylinder body located at the piston rod, so that during the movement of the piston rod, the piston rod can achieve a buffering action through the collision between the buffer ring and the cylinder body, and the friction between the buffer gasket and the piston rod. The above-mentioned buffer structure is complex in design, and the matching position of the piston rod and the buffer gasket, the matching position of the buffer gasket and the cylinder body, and the processing accuracy of the buffer ring are all very high, which is difficult in the processing process. In the subsequent long-term use of the piston rod, the wear amount is relatively serious, and the buffering effect is often not obvious, which also increases the introduction of noise.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0005] In order to overcome the defects in the prior art, an embodiment of the present invention provides a cylinder device and a buffering method with a buffer mechanism, which controls the flow of hydraulic oil out of and into the cylinder barrel per unit time through the oil circuit formed by the buffer ring gap, the groove body, and the through hole, thereby realizing the buffering action of the piston rod. The structure is ingenious and the coordination is simple.

[0006] The embodiment of the present application discloses: an oil cylinder device with a buffer mechanism, comprising a cylinder having a cavity, a piston rod located in the cylinder, and a piston fixedly connected to the piston rod, wherein the piston divides the cavity of the cylinder into two opposite first sealed spaces and a second sealed space, and further comprises an oil port portion and a buffer portion,

[0007] The oil port portion includes at least one through hole provided on the side wall of the cylinder;

[0008] The buffer portion includes a groove body opened on the side wall of the piston and capable of communicating with the first sealed space, a buffer ring arranged in the groove body and abutting against the inner wall of the cylinder, and a notch is arranged on the buffer ring, which can respectively communicate with the through hole and the first sealed space;

[0009] The oil cylinder device has a first oil circuit state, a second oil circuit state and a third oil circuit state. When in the first oil circuit state, the through hole is connected to the first sealed cavity through the groove body and the notch respectively; when in the second oil circuit state, the through hole is directly connected to the first sealed cavity; when in the third oil circuit state, the through hole is connected to the first sealed cavity through the notch;

[0010] The piston rod has an advancing state and a retreating state. When in the advancing state, the cylinder device is in a first oil circuit state when the buffer ring is located on the left side of the through hole; the cylinder device is in a second oil circuit state when the buffer ring is located on the right side of the through hole; when in the retreating state, the cylinder device is in the second oil circuit state when the buffer ring is located on the right side of the through hole; the cylinder device is in a third oil circuit state when the buffer ring is located on the left side of the through hole;

[0011] The flow rate of the hydraulic oil flowing through the through hole per unit time is greater than the sum of the flow rates of the hydraulic oil flowing through the groove body and the notch.

[0012] Furthermore, the buffer ring is made of elastic polymer material.

[0013] Furthermore, the buffer ring is made of PDFE material.

[0014] Furthermore, there are two through holes, and the two through holes are arranged opposite to each other along the moving direction of the piston rod; and there are two buffer parts, and they are arranged one-to-one corresponding to the through holes.

[0015] Furthermore, the through holes are respectively arranged at two ends adjacent to the cylinder.

[0016] Furthermore, the straight-line distance between the two through holes is greater than the length of the piston.

[0017] Furthermore, a sealing ring is provided on the side wall of the piston, and the outer end of the sealing ring abuts against the inner wall of the cylinder.

[0018] Furthermore, an oil storage groove is provided on the side wall of the piston, and the oil storage groove is located between the buffer portion and the sealing ring.

[0019] Furthermore, the first sealed cavity is located on the left side of the second sealed cavity.

[0020] The embodiment of the present application also discloses: a buffering method for an oil cylinder device, characterized in that it comprises the following steps:

[0021] In the forward state:

[0022] When the buffer ring at the left end is located on the left side of the left through hole and the buffer ring at the right end is located on the right side of the left through hole, hydraulic oil is injected from the left through hole, and the injected hydraulic oil pushes the buffer ring at the left end from the right side of the slot body to the left side of the slot body, so that the through hole on the left side is connected with the slot body; at this time, the buffer ring at the right end is located on the left side of the slot body corresponding to it;

[0023] The hydraulic oil is injected into the first sealed space through the notches of the groove body and the buffer ring, thereby pushing the piston rod to move rightward, and then squeezing the hydraulic oil in the second sealed space to flow out from the through hole on the right side;

[0024] When the buffer ring at the left end is located on the right side of the left through hole and the buffer ring at the right end is located on the left side of the right through hole, hydraulic oil is injected from the left through hole, and the injected hydraulic oil pushes the buffer ring at the left end from the left side of the slot body to the right side of the slot body; at this time, the buffer ring at the right end is located on the left side of the slot body corresponding to it;

[0025] The hydraulic oil is directly injected into the first sealed space, so as to push the piston rod to continue to move rightward, thereby squeezing the hydraulic oil in the second sealed space to flow out from the through hole on the right side;

[0026] When the buffer ring at the left end is located on the left side of the right through hole and the buffer ring at the right end is located on the right side of the right through hole, the hydraulic oil is injected from the left through hole, at which time the buffer ring at the left end is located on the right side of the corresponding groove body; the buffer ring at the right end is located on the left side of the corresponding groove body;

[0027] The hydraulic oil is directly injected into the first sealed space, so that the piston rod can continue to move rightward, and then the hydraulic oil in the second sealed space is squeezed to flow out from the through hole on the right side after passing through the notch of the right buffer ring, until the piston rod stops moving rightward;

[0028] In the backward state:

[0029] When the buffer ring at the right end is located on the right side of the right through hole and the buffer ring at the left end is located on the left side of the right through hole, hydraulic oil is injected from the right through hole, and the injected hydraulic oil pushes the buffer ring at the right end from the left side of the slot body to the right side of the slot body, so that the through hole on the right side is connected with the slot body; at this time, the buffer ring at the left end is located on the right side of the corresponding slot body;

[0030] The hydraulic oil is injected into the second sealed space through the notches of the groove body and the buffer ring, thereby pushing the piston rod to move leftward, and then squeezing the hydraulic oil in the first sealed space to flow out from the through hole on the left side;

[0031] When the buffer ring at the right end is located on the left side of the right through hole and the buffer ring at the left end is located on the right side of the left through hole, hydraulic oil is injected from the right through hole, and the injected hydraulic oil pushes the buffer ring at the right end from the right side of the slot body to the left side of the slot body; at this time, the buffer ring at the left end is located on the right side of the corresponding slot body;

[0032] The hydraulic oil is directly injected into the second sealed space, so as to push the piston rod to continue to move leftward, thereby squeezing the hydraulic oil in the first sealed space to flow out from the through hole on the left side;

[0033] When the buffer ring at the right end is located on the right side of the left through hole and the buffer ring at the left end is located on the left side of the left through hole, the hydraulic oil is injected from the right through hole, at which time the buffer ring at the right end is located on the left side of the corresponding groove body; the buffer ring at the left end is located on the right side of the corresponding groove body;

[0034] The hydraulic oil is directly injected into the second sealed space, so that the piston rod can continue to move leftward, and then the hydraulic oil in the first sealed space is squeezed to flow out from the through hole on the left side after passing through the gap of the left buffer ring, until the piston rod stops moving leftward;

[0035] Hydraulic oil is injected into the left through hole and the right through hole in sequence, so as to push the piston rod to move back and forth.

[0036] With the help of the above technical scheme, the beneficial effects of the present invention are as follows: through the oil circuit formed by the buffer ring gap, the groove body, and the through hole, the flow rate of the hydraulic oil flowing out and into the cylinder per unit time is controlled to achieve the buffering action of the piston rod, with ingenious structure and simple coordination.

[0037] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 12 is a schematic diagram of the overall structure of the device in the first position when the piston rod moves rightward in an embodiment of the present invention;

[0040] Figure 2 yes Figure 1 A magnified view of the structure at center A;

[0041] Figure 3 2 is a schematic diagram of the overall structure of the device in the second position when the piston rod moves rightward in an embodiment of the present invention;

[0042] Figure 4 yes Figure 3 A magnified view of the structure at B in the middle;

[0043] Figure 5 2 is a schematic diagram of the overall structure of the device in the third position when the piston rod moves rightward in an embodiment of the present invention;

[0044] Figure 6 yes Figure 5 A magnified view of the structure at C in the middle;

[0045] Figure 7 2 is a schematic diagram of the overall structure of the device in the first position when the piston rod moves leftward in an embodiment of the present invention;

[0046] Figure 8 yes Figure 7 A magnified view of the structure at D in the middle;

[0047] Fig. 9 2 is a schematic diagram of the overall structure of the device in the second position when the piston rod moves leftward in an embodiment of the present invention;

[0048] Fig.10 yes Fig. 9 A magnified view of the structure at E in the middle;

[0049] Fig.11 2 is a schematic diagram of the overall structure of the device in the third position when the piston rod moves leftward in an embodiment of the present invention;

[0050] Fig.12 yes Fig.11 A magnified view of the structure at F in the middle;

[0051] Fig.13 It is a schematic diagram of the structure of the buffer exchange in the present invention.

[0052] The figure numbers of the above drawings are: 1. cylinder; 2. piston rod; 3. piston; 4. first sealed space; 5. second sealed space; 6. through hole; 7. groove body; 8. buffer ring; 9. notch. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are only used for descriptive purposes and to distinguish similar objects. There is no order of precedence between the two, and they cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0055] Combination Figure 1 and Fig.13 As shown, this embodiment discloses a cylinder device with a buffer mechanism, including a cylinder 1 with a cavity, a piston 3 rod 2 located in the cylinder 1, and a piston 3 fixedly connected to the piston 3 rod 2, wherein the piston 3 divides the cavity of the cylinder 1 into two opposite first sealed spaces 4 and second sealed spaces 5. The cylinder device also includes an oil port portion and a buffer portion, wherein the oil port portion includes at least one through hole 6 provided on the side wall of the cylinder 1; the buffer portion includes a groove body 7 provided on the side wall of the piston 3 and capable of communicating with the first sealed space 4, and a buffer ring 8 provided in the groove body 7 and abutting against the inner side wall of the cylinder 1, wherein a notch 9 capable of respectively communicating with the through hole 6 and the first sealed space 4 is provided on the buffer ring 8.

[0056] In the above-mentioned arrangement, when the oil circuit is in the through hole 6 to the groove body 7, and then to the first sealed space 4 or the second sealed space 5, it is in a slow start state; when the oil circuit is in the through hole 6 to the first sealed space 4 or the second sealed space 5, since the hydraulic oil flow rate flowing through the through hole 6 per unit time is greater than the hydraulic oil flow rate flowing through the groove body 7 per the same unit time, it is in a fast running state; when the oil circuit is in the first sealed space 4 or the second sealed space 5 to the gap 9 of the buffer ring 8, and then to the through hole 6, since the hydraulic oil flow rate flowing through the gap 9 of the buffer ring 8 per unit time is less than the hydraulic oil flow rate flowing through the groove body 7 per the same unit time, it is in a buffer stop state. The oil circuit formed by the gap 9 of the buffer ring 8, the groove body 7, and the through hole 6 controls the flow rate of the hydraulic oil flowing out and into the cylinder 1 per unit time, thereby realizing the buffering action of the piston 3 and the rod 2, with an ingenious structure and simple coordination.

[0057] In this embodiment, two through holes 6 are provided, and the two through holes 6 are arranged opposite to each other along the movement direction of the piston 3 rod 2; two buffer parts are provided, and they are arranged one by one corresponding to the through holes 6. The through holes 6 are respectively provided at the two ends near the cylinder tube 1. Specifically, the oil cylinder is in the shape of a hollow cylinder as a whole and extends in the left and right directions. There are two through holes 6, which are respectively provided at the left end and the right end near the oil cylinder.

[0058] In this embodiment, the straight distance between the two through holes 6 is greater than the length of the piston 3. This ensures that the oil cylinder has the through hole 6 on the left side directly inlet oil while the through hole 6 on the right side directly outlet oil, thereby ensuring that the oil cylinder device has a normal working state of fast operation.

[0059] In this embodiment, the buffer ring 8 is sleeved in the groove body 7. Preferably, the buffer ring 8 is made of elastic polymer material, such as PDFE material.

[0060] In this embodiment, the oil cylinder device has a first oil circuit state, a second oil circuit state and a third oil circuit state. When in the first oil circuit state, the through hole 6 is connected to the first sealed cavity through the groove body 7 and the notch 9 respectively. When in the second oil circuit state, the through hole 6 is directly connected to the first sealed cavity. When in the third oil circuit state, the through hole 6 is connected to the first sealed cavity through the notch 9. The piston 3 rod 2 has a forward state and a backward state. When in the forward state, the oil cylinder device is in the first oil circuit state when the buffer ring 8 is located on the left side of the through hole 6. The oil cylinder device is in the second oil circuit state when the buffer ring 8 is located on the right side of the through hole 6. When in the backward state, the oil cylinder device is in the second oil circuit state when the buffer ring 8 is located on the right side of the through hole 6. The oil cylinder device is in the third oil circuit state when the buffer ring 8 is located on the left side of the through hole 6. The flow rate of the hydraulic oil flowing through the through hole 6 per unit time is greater than the sum of the flow rates of the hydraulic oil flowing through the groove body 7 and the notch 9 .

[0061] In this embodiment, a sealing ring is provided on the side wall of the piston 3, and the outer end of the sealing ring abuts against the inner wall of the cylinder 1. The sealing ring can further ensure the relative sealing between the first sealed space 4 and the second sealed space 5.

[0062] In this embodiment, an oil storage groove is provided on the side wall of the piston 3, and the oil storage groove is located between the buffer portion and the sealing ring. Figure 1As shown, it is generally in the shape of an inverted trapezoid. When oil enters from the through hole 6, it can have a buffering effect on the injected hydraulic oil, thereby preventing the piston 3 from being subjected to excessive impact force, thereby reducing the probability of the piston 3 being damaged and the sliding being unstable.

[0063] Combination Figure 1 and Figure 2 As shown, at this time, the cylinder device is in the forward state, and the buffer ring 8 at the left end is located on the left side of the left through hole 6 and the buffer ring 8 at the right end is located on the right side of the left through hole 6. At this time, the hydraulic oil is injected from the left through hole 6, and the injected hydraulic oil pushes the buffer ring 8 at the left end from the right side of the slot body 7 to the left side of the slot body 7, so that the through hole 6 on the left side is connected with the slot body 7; at this time, the buffer ring 8 at the right end is located on the left side of the corresponding slot body 7. The hydraulic oil is injected into the first sealed space 4 through the notches 9 of the slot body 7 and the buffer ring 8 respectively, so that the piston 3 rod 2 can be pushed to move to the right, and then the hydraulic oil in the second sealed space 5 is squeezed out of the through hole 6 on the right. At this time, the cylinder device can be defined as being in the buffered forward state.

[0064] Combination Figure 3 and Figure 4 As shown, at this time, the cylinder device is in the forward state, and the buffer ring 8 at the left end is located on the right side of the left through hole 6 and the buffer ring 8 at the right end is located on the left side of the right through hole 6. At this time, the hydraulic oil is injected from the left through hole 6, and the injected hydraulic oil pushes the buffer ring 8 at the left end from the left side of the groove body 7 to the right side of the groove body 7; at this time, the buffer ring 8 at the right end is located on the left side of the corresponding groove body 7. The hydraulic oil is directly injected into the first sealed space 4, so that the piston 3 rod 2 can continue to move to the right, and then squeeze the hydraulic oil in the second sealed space 5 to flow out from the through hole 6 on the right. At this time, the cylinder device can be defined as being in a fast forward state.

[0065] Combination Figure 5 and Figure 6 As shown, at this time, the cylinder device is in the forward state, and the buffer ring 8 at the left end is located on the left side of the right through hole 6 and the buffer ring 8 at the right end is located on the right side of the right through hole 6. At this time, the hydraulic oil is injected from the left through hole 6, and the buffer ring 8 at the left end is located on the right side of the corresponding groove body 7; the buffer ring 8 at the right end is located on the left side of the corresponding groove body 7. The hydraulic oil is directly injected into the first sealed space 4, so that the piston 3 rod 2 can continue to move to the right, and then squeeze the hydraulic oil in the second sealed space 5 to flow out of the right through hole 6 after passing through the notch 9 of the right buffer ring 8, until the piston 3 rod 2 stops moving to the right. At this time, the cylinder device can be defined as being in a buffer stop state.

[0066] Combination Figure 7 and Figure 8As shown, at this time, the cylinder device is in a retreat state, and the buffer ring 8 at the right end is located on the right side of the right through hole 6 and the buffer ring 8 at the left end is located on the left side of the right through hole 6. At this time, the hydraulic oil is injected from the right through hole 6, and the injected hydraulic oil pushes the buffer ring 8 at the right end from the left side of the slot body 7 to the right side of the slot body 7, so that the through hole 6 on the right side is connected with the slot body 7; at this time, the buffer ring 8 at the left end is located on the right side of the corresponding slot body 7. The hydraulic oil is injected into the second sealed space 5 through the notches 9 of the slot body 7 and the buffer ring 8 respectively, so that the piston 3 rod 2 can be pushed to move to the left, and then the hydraulic oil in the first sealed space 4 is squeezed out of the through hole 6 on the left. At this time, it can be defined that the cylinder device is in a buffer retreat state.

[0067] Combination Fig. 9 and Fig.10 As shown, at this time, the cylinder device is in a retreat state, and the buffer ring 8 at the right end is located on the left side of the right through hole 6 and the buffer ring 8 at the left end is located on the right side of the left through hole 6. At this time, the hydraulic oil is injected from the right through hole 6, and the injected hydraulic oil pushes the buffer ring 8 at the right end from the right side of the groove body 7 to the left side of the groove body 7; at this time, the buffer ring 8 at the left end is located on the right side of the corresponding groove body 7. The hydraulic oil is directly injected into the second sealed space 5, so that the piston 3 rod 2 can continue to move to the left, and then squeeze the hydraulic oil in the first sealed space 4 to flow out from the through hole 6 on the left. At this time, it can be defined that the cylinder device is in a rapid retreat state.

[0068] Combination Fig.11 and Fig.12 As shown, at this time, the cylinder device is in a backward state, and the buffer ring 8 at the right end is located on the right side of the left through hole 6 and the buffer ring 8 at the left end is located on the left side of the left through hole 6. At this time, the hydraulic oil is injected from the right through hole 6, and the buffer ring 8 at the right end is located on the left side of the corresponding groove body 7; the buffer ring 8 at the left end is located on the right side of the corresponding groove body 7. The hydraulic oil is directly injected into the second sealed space 5, so that the piston 3 rod 2 can continue to move to the left, and then squeeze the hydraulic oil in the first sealed space 4 to flow out of the left through hole 6 after passing through the notch 9 of the left buffer ring 8, until the piston 3 rod 2 stops moving to the left. At this time, it can be defined that the cylinder device is in a buffer stop state.

[0069] In summary, hydraulic oil is injected into the left through hole 6 and the right through hole 6 in sequence, so as to push the piston 3 and the rod 2 to reciprocate.

[0070] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A cylinder device with a buffer mechanism, comprising a cylinder having a cavity, a piston rod located in the cylinder, and a piston fixedly connected to the piston rod, wherein the piston divides the cavity of the cylinder into two opposite first sealed spaces and a second sealed space, characterized in that: It also includes the oil port and buffer part. The oil port portion includes at least one through hole provided on the side wall of the cylinder barrel; The buffer portion includes a groove body opened on the side wall of the piston and capable of communicating with the first sealed space, a buffer ring arranged in the groove body and abutting against the inner wall of the cylinder, and a notch is arranged on the buffer ring, which can respectively communicate with the through hole and the first sealed space; The oil cylinder device has a first oil circuit state, a second oil circuit state and a third oil circuit state. When in the first oil circuit state, the through hole is connected to the first sealed space through the groove body and the notch respectively; when in the second oil circuit state, the through hole is directly connected to the first sealed space; when in the third oil circuit state, the through hole is connected to the first sealed space through the notch; The piston rod has an advancing state and a retreating state. When in the advancing state, the cylinder device is in a first oil circuit state when the buffer ring is located on the left side of the through hole; the cylinder device is in a second oil circuit state when the buffer ring is located on the right side of the through hole; when in the retreating state, the cylinder device is in the second oil circuit state when the buffer ring is located on the right side of the through hole; the cylinder device is in a third oil circuit state when the buffer ring is located on the left side of the through hole; The flow rate of the hydraulic oil flowing through the through hole per unit time is greater than the sum of the flow rates of the hydraulic oil flowing through the groove body and the notch; There are two through holes, and the two through holes are arranged opposite to each other along the movement direction of the piston rod; there are two buffer parts, and they are arranged one by one corresponding to the through holes; A sealing ring is provided on the side wall of the piston, and the outer end of the sealing ring abuts against the inner wall of the cylinder; An oil storage groove is provided on the side wall of the piston, and the oil storage groove is located between the buffer part and the sealing ring.

2. The oil cylinder device with a buffer mechanism according to claim 1, characterized in that: The buffer ring is made of elastic polymer material.

3. The oil cylinder device with a buffer mechanism according to claim 2, characterized in that: The buffer ring is made of PDFE material.

4. The oil cylinder device with a buffer mechanism according to claim 1, characterized in that: The through holes are respectively arranged at both ends adjacent to the cylinder.

5. The oil cylinder device with a buffer mechanism according to claim 1, characterized in that: The straight-line distance between the two through holes is greater than the length of the piston.

6. The oil cylinder device with a buffer mechanism according to claim 1, characterized in that: The first sealed space is located on the left side of the second sealed space.

7. A buffering method for a cylinder device, used for a cylinder device with a buffering mechanism according to any one of claims 1 to 6, characterized in that: The following steps are involved: In the forward state: When the buffer ring at the left end is located on the left side of the left through hole and the buffer ring at the right end is located on the right side of the left through hole, hydraulic oil is injected from the left through hole, and the injected hydraulic oil pushes the buffer ring at the left end from the right side of the slot body to the left side of the slot body, so that the through hole on the left side is connected with the slot body; at this time, the buffer ring at the right end is located on the left side of the slot body corresponding to it; The hydraulic oil is injected into the first sealed space through the notches of the groove body and the buffer ring, thereby pushing the piston rod to move rightward, and then squeezing the hydraulic oil in the second sealed space to flow out from the through hole on the right side; When the buffer ring at the left end is located on the right side of the left through hole and the buffer ring at the right end is located on the left side of the right through hole, hydraulic oil is injected from the left through hole, and the injected hydraulic oil pushes the buffer ring at the left end from the left side of the slot body to the right side of the slot body; at this time, the buffer ring at the right end is located on the left side of the slot body corresponding to it; The hydraulic oil is directly injected into the first sealed space, so as to push the piston rod to continue to move rightward, thereby squeezing the hydraulic oil in the second sealed space to flow out from the through hole on the right side; When the buffer ring at the left end is located on the left side of the right through hole and the buffer ring at the right end is located on the right side of the right through hole, the hydraulic oil is injected from the left through hole, at which time the buffer ring at the left end is located on the right side of the corresponding groove body; the buffer ring at the right end is located on the left side of the corresponding groove body; The hydraulic oil is directly injected into the first sealed space, so that the piston rod can continue to move rightward, and then the hydraulic oil in the second sealed space is squeezed to flow out from the through hole on the right side after passing through the notch of the right buffer ring, until the piston rod stops moving rightward; In the backward state: When the buffer ring at the right end is located on the right side of the right through hole and the buffer ring at the left end is located on the left side of the right through hole, hydraulic oil is injected from the right through hole, and the injected hydraulic oil pushes the buffer ring at the right end from the left side of the slot body to the right side of the slot body, so that the through hole on the right side is connected with the slot body; at this time, the buffer ring at the left end is located on the right side of the corresponding slot body; The hydraulic oil is injected into the second sealed space through the notches of the groove body and the buffer ring, thereby pushing the piston rod to move leftward, and then squeezing the hydraulic oil in the first sealed space to flow out from the through hole on the left side; When the buffer ring at the right end is located on the left side of the right through hole and the buffer ring at the left end is located on the right side of the left through hole, hydraulic oil is injected from the right through hole, and the injected hydraulic oil pushes the buffer ring at the right end from the right side of the slot body to the left side of the slot body; at this time, the buffer ring at the left end is located on the right side of the corresponding slot body; The hydraulic oil is directly injected into the second sealed space, so as to push the piston rod to continue to move leftward, thereby squeezing the hydraulic oil in the first sealed space to flow out from the through hole on the left side; When the buffer ring at the right end is located on the right side of the left through hole and the buffer ring at the left end is located on the left side of the left through hole, the hydraulic oil is injected from the right through hole, at which time the buffer ring at the right end is located on the left side of the corresponding groove body; the buffer ring at the left end is located on the right side of the corresponding groove body; The hydraulic oil is directly injected into the second sealed space, so that the piston rod can continue to move leftward, and then the hydraulic oil in the first sealed space is squeezed to flow out from the through hole on the left side after passing through the gap of the left buffer ring, until the piston rod stops moving leftward; Hydraulic oil is injected into the left through hole and the right through hole in sequence, so as to push the piston rod to move back and forth.

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