Shock absorber

Abstract

The shock absorber comprises a cylinder barrel and a piston assembly, and a control oil cavity, an overflow block, a valve element, an oil discharging channel and an oil discharging pipe are arranged in the piston assembly; the valve element is sequentially provided with a large-diameter section and a small-diameter section in the axial direction of the valve element. The overflow block is of an annular structure with a hollow part, the valve element is arranged in the hollow part of the overflow block in the mode of being capable of moving in the axial direction, a first oil channel is formed between the small-diameter section and the side wall of the hollow part, and a first overflow hole communicating with the first oil channel and the control oil cavity is formed in the side wall of the overflow block. A second overflow hole communicated with the oil discharge channel is further formed in the side wall of the overflow block; the interior of the valve element comprises a hollow structure extending in the axial direction, and the oil discharging pipe is arranged in the hollow structure of the valve element. The end, relatively away from the large-diameter section, of the valve element is in sealing fit with the side wall of the hollow part of the overflow block. The piston assembly is provided with a second overflow channel communicated with the sealing cavity and the rodless cavity. According to the shock absorber provided by the invention, the problem of pollution caused by easy leakage of oil can be avoided.

Description

Technical Field

[0001] The invention relates to a shock absorber. Background Art

[0002] The shock absorber is an important component of the vehicle chassis system, which can effectively buffer the vibration of the vehicle chassis. The shock absorber includes a cylinder, a piston assembly, and a piston rod connected to the piston assembly. The piston assembly is in a sealed fit with the inner wall of the cylinder, thereby dividing the space of the cylinder into a first working space and a second working space, and the piston rod is located in one of the working spaces. The piston assembly includes a piston body, a valve group connected to the piston body, and an oil circuit arranged on the piston body.

[0003] The oil circuit can connect the first working space and the second working space, and the valve group is used to control the opening and closing of the oil circuit. When the piston body moves up and down in the cylinder, the oil in the first working space and the second working space can flow back and forth through the oil circuit through the control of the valve group. At this time, the oil in the oil circuit will form a damping effect on the movement of the piston body, thereby playing a role in shock absorption.

[0004] The valve group includes devices such as a solenoid, a valve seat and a valve core. A magnetic field force can be generated by passing an electric current through the solenoid, and under the action of the magnetic field force, the valve core forms a certain damping force on the oil.

[0005] Due to structural limitations of the valve group structure in the prior art, a relatively large radial clearance needs to be reserved between the valve core and the valve seat in the radial direction, which may cause oil leakage and contamination. Summary of the invention

[0006] The object of the present invention is to provide a shock absorber which can avoid the problem of oil leakage causing pollution.

[0007] The present invention provides a shock absorber, comprising a cylinder and a piston assembly, wherein the piston assembly divides the cylinder into a rod chamber and a rodless chamber, and a control oil chamber, an overflow block, a valve core, an oil unloading channel, and an oil unloading pipe are arranged inside the piston assembly; wherein,

[0008] The valve core is provided with a large diameter section and a small diameter section in sequence along its axial direction, and the diameter of the large diameter section is larger than the diameter of the small diameter section;

[0009] The overflow block is an annular structure with a hollow portion, the valve core is axially displaceably arranged in the hollow portion of the overflow block, and a first oil passage is formed between the small diameter section and the side wall of the hollow portion, a first overflow hole communicating with both the first oil passage and the control oil chamber is arranged on the side wall of the overflow block, and a second overflow hole communicating with the oil unloading passage is also arranged on the side wall of the overflow block; wherein,

[0010] The valve core can be switched between a first position and a second position along the axial direction. When in the first position, the large diameter section of the valve core separates the first oil passage and the second overflow hole. When in the second position, the first oil passage is connected to the second overflow hole.

[0011] The interior of the valve core includes a hollow structure extending in the axial direction, the oil unloading pipe is arranged in the hollow structure of the valve core, and the oil unloading pipe partially extends out of the valve core and is arranged in the overflow block, the oil unloading pipe is respectively connected with the oil unloading channel and the rodless cavity, and is used to introduce the oil in the oil unloading channel into the rodless cavity;

[0012] One end of the valve core relatively away from the large diameter section is in sealing cooperation with the side wall of the hollow portion of the overflow block, and when the valve core is located at the second position, the lower end of the valve core, the side wall of the hollow portion of the overflow block and the outer wall of the oil unloading pipe together form a sealing cavity;

[0013] The piston assembly is provided with a second overflow channel communicating with the sealing chamber and the rodless chamber.

[0014] According to the shock absorber provided by the present invention, the hollow portion of the overflow block includes a first hollow portion, a second hollow portion and a third hollow portion in sequence along the axial direction, the diameter of the first hollow portion is larger than the diameter of the second hollow portion, the diameter of the second hollow portion is larger than the diameter of the third hollow portion; and,

[0015] The first hollow portion is sealed with the large diameter section of the valve core, the second hollow portion is sealed with an end of the valve core relatively away from the large diameter section, and the third hollow portion is sealed with the oil unloading pipe.

[0016] According to the shock absorber provided by the present invention, the second overflow holes are provided in plurality and are evenly distributed along the circumference of the overflow block.

[0017] According to the shock absorber provided by the present invention, a first overflow channel is provided in the piston assembly, and the first overflow channel connects the rod chamber and the rodless chamber.

[0018] According to the shock absorber provided by the present invention, the valve core is arranged at the axial center position of the piston assembly.

[0019] According to the shock absorber provided by the present invention, the oil unloading pipe and the overflow block are relatively fixed, and the oil unloading pipe and the valve core can slide relatively.

[0020] According to the shock absorber provided by the present invention, the piston assembly is provided with a first oil circuit, a second oil circuit, a third oil circuit and a fourth oil circuit; wherein,

[0021] One end of the first oil circuit and the second oil circuit is connected to the rod chamber, the other end of the first oil circuit is connected to the control oil chamber, and the other end of the second oil circuit is connected to the oil unloading channel; one end of the third oil circuit and the fourth oil circuit is connected to the rodless chamber, the other end of the third oil circuit is connected to the control oil chamber, and the other end of the fourth oil circuit is connected to the oil unloading pipe.

[0022] According to the shock absorber provided by the present invention, the valve includes a first one-way valve and a third one-way valve, and the piston assembly also includes a second one-way valve and a fourth one-way valve, wherein the first one-way valve, the second one-way valve, the third one-way valve and the fourth one-way valve are respectively arranged in one-to-one correspondence with the first oil circuit, the second oil circuit, the third oil circuit and the fourth oil circuit;

[0023] When the oil pressure in the rod chamber is greater than the oil pressure in the control oil chamber, and the oil pressure in the control oil chamber is greater than the oil pressure in the rodless chamber, the first one-way valve and the fourth one-way valve are connected; when the oil pressure in the rodless chamber is greater than the oil pressure in the control oil chamber, and the oil pressure in the control oil chamber is greater than the oil pressure in the rod chamber, the third one-way valve and the second one-way valve are connected.

[0024] The shock absorber provided by the present invention comprises a cylinder and a piston assembly. It should be noted that the piston assembly comprises a piston body, a piston ring, various valve structures connected to the piston body, and other components connected to the piston body and reciprocating with the piston body. The piston assembly is connected to the piston rod through a connecting structure, and the piston assembly divides the cylinder into a rod chamber and a rodless chamber. A control oil chamber, an overflow block, a valve core, an oil unloading channel and an oil unloading pipe are arranged inside the piston assembly; wherein valves are arranged between the control oil chamber and the rod chamber and the rodless chamber; the valve core is provided with a large diameter section and a small diameter section in sequence along its axial direction, and the diameter of the large diameter section is larger than the diameter of the small diameter section; the overflow block is an annular structure with a hollow portion, and the valve core can be axially displaced in the hollow portion of the overflow block, and a first oil channel is formed between the small diameter section and the side wall of the hollow portion, and a first overflow hole connected to the first oil channel and the control oil chamber is arranged on the side wall of the overflow block, and a second overflow hole connected to the oil unloading channel is also arranged on the side wall of the overflow block; wherein the valve core can switch between a first position and a second position along the axial direction, and in the first position, the large diameter section of the valve core separates the first oil channel and the second overflow hole, and in the second position, the first oil channel is connected to the second overflow hole. It should be noted that when the shock absorber is in a non-working state, the oil pressure in the rod chamber and the rodless chamber is in a balanced state, and the valve core is kept in the first position under the magnetic field force generated by the solenoid, directly isolating the first oil channel and the second overflow hole. When the shock absorber is in a compression stroke, the oil pressure in the rodless chamber increases, and the oil in the rodless chamber enters the control oil chamber through the valve, the oil pressure in the control oil chamber increases, and enters the first oil channel through the first overflow hole, and the oil pressure acts on the stepped surface formed by the large diameter section and the small diameter section of the valve core, thereby pushing the valve core to overcome the magnetic field force and axially displace to the second position. At this time, the first oil channel is connected to the second overflow hole, and the oil in the first oil channel enters the oil unloading channel through the second overflow hole, and enters the rod chamber through the oil unloading channel, thereby realizing the damping effect of the shock absorber. When the shock absorber is in the rebound stroke, the oil pressure in the rod chamber increases, and the oil in the rod chamber enters the control oil chamber through the valve, the oil pressure in the control oil chamber increases, and enters the first oil channel through the first overflow hole, and the oil pressure acts on the step surface formed by the large diameter section and the small diameter section of the valve core, thereby pushing the valve core to overcome the magnetic field force and axially displace to the second position. At this time, the first oil channel is connected to the second overflow hole, and the oil in the first oil channel enters the oil unloading channel through the second overflow hole, and the oil in the oil unloading channel enters the oil unloading pipe, and enters the rodless chamber through the oil unloading pipe, thereby realizing the damping effect of the shock absorber.

[0025] In addition, one end of the valve core that is relatively far from the large diameter section is sealed with the side wall of the hollow part of the overflow block. When the valve core is located between the first position and the second position, the lower end of the valve core, the side wall of the hollow part of the overflow block and the outer wall of the oil unloading pipe together form a sealed cavity, and the piston assembly is provided with a second overflow channel connected to the sealed cavity and the rodless cavity. With such a configuration, when the shock absorber is in a compression stroke, the oil can enter the control oil chamber and the second overflow channel at the same time under the action of pressure. The oil entering the control oil chamber enters the first oil channel through the first overflow hole, and the oil pressure acts on the stepped surface formed by the large diameter section and the small diameter section of the valve core, thereby pushing the valve core to overcome the magnetic field force and move to the second position; at the same time, the oil enters the second overflow channel, and the oil pressure acts on the end of the valve core, which can play a role in assisting the valve core. The aperture size of the second overflow channel can be designed accordingly according to the different damping forces required by the shock absorber. Obviously, the present invention forms a sliding valve structure by setting the valve core in a sliding form, and realizes the on-off control of the oil circuit by cooperating with the overflow block. The sliding valve structure has good stability and can effectively avoid the problem of oil leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 FIG. 4 is a schematic cross-sectional view of a piston assembly according to an embodiment of the present invention.

[0027] Figure 2 It is a schematic diagram showing the matching structure of the oil discharge pipe and the overflow block of the piston assembly according to an embodiment of the present invention.

[0028] Figure 3 FIG. 1 is a partial cross-sectional schematic diagram of a piston assembly according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following detailed description and drawings are used to illustrate the principle of the present invention. The present invention is not limited to the preferred embodiments described. The protection scope of the present invention is defined by the claims.

[0030] It should be noted that the orientations or positional relationships indicated in this specification are based on the orientations or positional relationships described in the accompanying drawings and are only for the convenience and simplification of description, and do not indicate or imply that the device referred to must have a specific orientation or be constructed in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0031] Please refer to Figure 1-Figure 3 The shock absorber provided in this embodiment includes a cylinder and a piston assembly 1, wherein the piston assembly 1 is provided with a control oil chamber 11, an overflow block 23, a solenoid, a valve core 28, an oil discharge channel 15, etc. The solenoid can generate a magnetic field when current is passed through it, and the valve core 28 is acted upon by the magnetic field force.

[0032] The piston assembly 1 is connected to the piston rod through a connecting structure. The piston body of the piston assembly 1 is sealed with the inner wall of the cylinder, and the piston assembly 1 can slide along the axial direction of the cylinder. The piston assembly 1 divides the cylinder into a rod chamber and a rodless chamber.

[0033] The piston assembly 1 is provided with a control oil chamber 11, an overflow block 23, a valve core 28, an oil unloading channel 15, and an oil unloading pipe 24; valves are provided between the control oil chamber 11 and the rod chamber and the rodless chamber. When the shock absorber is in the compression stroke, the oil pressure in the rodless chamber is greater than the opening threshold of the valve between the rodless chamber and the control oil chamber 11, and the oil can enter the control oil chamber 11 from the rodless chamber. When the shock absorber is in the rebound stroke, the oil pressure in the rod chamber is greater than the opening threshold of the valve between the rod chamber and the control oil chamber 11, and the oil can enter the control oil chamber 11 from the rod chamber.

[0034] The valve core 28 is set as a cylindrical structure, and a large diameter section 27 and a small diameter section 26 are sequentially arranged along its axial direction. The diameter of the large diameter section 27 is larger than the diameter of the small diameter section 26, and the large diameter section 27 and the small diameter section 26 constitute a stepped shaft structure, and a stepped surface is formed between the two.

[0035] The overflow block 23 is an annular structure with a hollow portion, and the valve core 28 is axially displaceably disposed in the hollow portion of the overflow block 23, and a first oil passage 25 is formed between the small diameter section 26 and the side wall of the hollow portion, and a first overflow hole 13 communicating with both the first oil passage 25 and the control oil chamber 11 is disposed on the side wall of the overflow block 23, and a second overflow hole 14 communicating with the oil discharge channel 15 is also disposed on the side wall of the overflow block 23. The valve core 28 can be switched between a first position and a second position along the axial direction, and in the first position, the large diameter section 27 of the valve core 28 separates the first oil passage 25 and the second overflow hole 14, and in the second position, the first oil passage 25 is communicated with the second overflow hole 14.

[0036] It should be noted that when the shock absorber is in a non-working state, the oil pressure in the rod chamber and the rodless chamber is in a balanced state, and the valve core 28 is maintained in the first position under the action of the magnetic field force generated by the solenoid, directly isolating the first oil channel 25 and the second overflow hole 14.

[0037] When the shock absorber is in the compression stroke, the oil pressure in the rodless chamber increases, and the oil in the rodless chamber enters the control oil chamber 11 through the valve, the oil pressure in the control oil chamber 11 increases, and enters the first oil passage 25 through the first overflow hole 13, and the oil pressure acts on the stepped surface formed by the large diameter section 27 and the small diameter section 26 of the valve core 28, thereby pushing the valve core 28 to overcome the magnetic field force and axially displace to the second position.

[0038] At this time, the first oil channel 25 is connected to the second overflow hole 14, and the oil in the first oil channel 25 enters the oil unloading channel 15 through the second overflow hole 14. The oil in the oil unloading channel 15 enters the oil unloading pipe 24 and enters the rodless cavity through the oil unloading pipe 24, thereby realizing the damping effect of the shock absorber.

[0039] In addition, one end of the valve core 28 that is relatively far from the large diameter section 27 is sealed with the side wall of the hollow part of the overflow block 23. When the valve core 28 is located between the first position and the second position, the lower end of the valve core 28, the side wall of the hollow part of the overflow block 23 and the outer wall of the oil discharge pipe 24 together form a sealed cavity, and the piston assembly 1 is provided with a second overflow channel 19 that is connected to the sealed cavity and the rodless cavity. In this way, when the shock absorber is in the compression stroke, the oil can enter the control oil chamber 11 and the second overflow channel 19 at the same time under the action of pressure. The oil entering the control oil chamber 11 enters the first oil channel 25 through the first overflow hole 13, and the oil pressure acts on the stepped surface formed by the large diameter section 27 and the small diameter section 26 of the valve core 28, thereby pushing the valve core 28 to overcome the magnetic field force and move to the second position. At the same time, the oil enters the second overflow channel 19, and the oil pressure acts on the end of the valve core 28, which can play a role in assisting the valve core 28. The aperture size of the second overflow channel 19 can be designed accordingly according to the damping force required by the shock absorber.

[0040] Obviously, in this embodiment, the valve core 28 is set to a sliding form to form a sliding valve structure, and the on-off control of the oil circuit is achieved by cooperating with the overflow block 23. The sliding valve structure has good stability and can effectively avoid the problem of oil leakage.

[0041] In a further embodiment, the hollow portion of the overflow block 23 includes a first hollow portion, a second hollow portion, and a third hollow portion in sequence along the axial direction. The diameter of the first hollow portion is greater than the diameter of the second hollow portion, and the diameter of the second hollow portion is greater than the diameter of the third hollow portion. Moreover, the first hollow portion is sealed with the large diameter section 27 of the valve core 28, the second hollow portion is sealed with an end of the valve core 28 relatively away from the large diameter section 27, and the third hollow portion is sealed with the oil unloading pipe 24.

[0042] With such arrangement, the risk of oil leakage can be further prevented through the precise cooperation between the overflow block 23, the valve core 28 and the oil discharge pipe 24.

[0043] In a further embodiment, there may be a plurality of second overflow holes 14 on the overflow block 23, and the overflow holes 14 may be evenly distributed along the circumference of the overflow block 23. In this embodiment, the damping force of the shock absorber can be adjusted by designing different numbers of second overflow holes 14. Therefore, the shock absorber provided in this embodiment has a larger adjustment range of the damping force.

[0044] In a further embodiment, a first overflow channel 29 is provided in the piston assembly 1, and the first overflow channel 29 connects the rod chamber and the rodless chamber. When the shock absorber is in a compression stroke or a rebound stroke, the oil in the rod chamber and the rodless chamber can flow through the first overflow channel 29, thereby playing a role in lowering the damping force of the shock absorber. It should be noted that the aperture size of the first overflow channel 29 can be set according to the damping force requirement of the shock absorber.

[0045] In a further embodiment, a first oil circuit, a second oil circuit 16, a third oil circuit 20 and a fourth oil circuit 21 are provided in the piston assembly 1. One end of the first oil circuit and the second oil circuit 16 is communicated with the rod chamber, the other end of the first oil circuit is communicated with the control oil chamber 11, and the other end of the second oil circuit 16 is communicated with the oil unloading passage 15; one end of the third oil circuit 20 and the fourth oil circuit 21 is communicated with the rodless chamber, the other end of the third oil circuit 20 is communicated with the control oil chamber 11, and the other end of the fourth oil circuit 21 is communicated with the oil unloading pipe 24.

[0046] The valves include a first one-way valve 12 and a third one-way valve 18, and the piston assembly 1 also includes a second one-way valve 17 and a fourth one-way valve 22. The first one-way valve 12, the second one-way valve 17, the third one-way valve 18 and the fourth one-way valve 22 are respectively arranged in a one-to-one correspondence with the first oil circuit, the second oil circuit 16, the third oil circuit 20 and the fourth oil circuit 21.

[0047] When the oil pressure in the rod chamber is greater than the oil pressure in the control oil chamber 11, and the oil pressure in the control oil chamber 11 is greater than the oil pressure in the rodless chamber, the first one-way valve 12 and the fourth one-way valve 22 are connected; when the oil pressure in the rodless chamber is greater than the oil pressure in the control oil chamber 11, and the oil pressure in the control oil chamber 11 is greater than the oil pressure in the rod chamber, the third one-way valve 18 and the second one-way valve 17 are connected.

[0048] With such arrangement, when the shock absorber is in the compression stroke, the oil in the rodless chamber passes through the third oil passage 20 and the third one-way valve 18 to enter the control oil chamber 11, and then flows through the first overflow hole 13 and the first oil passage 25 in sequence, and the oil pressure acts on the stepped surface formed by the large diameter section 27 and the small diameter section 26 of the valve core 28, thereby pushing the valve core 28 to overcome the magnetic field force and axially displace to the second position. At this time, the first oil passage 25 is connected with the second overflow hole 14, and the oil in the first oil passage 25 enters the oil unloading passage 15 through the second overflow hole 14, and then flows through the second one-way valve 17 and the second oil passage 16 in sequence after entering the oil unloading passage 15 to enter the rod chamber.

[0049] When the shock absorber is in the rebound stroke, the oil in the rod chamber passes through the first oil circuit and the first one-way valve 12 to enter the control oil chamber 11, and then flows through the first overflow hole 13 and the first oil channel 25 in sequence. The oil pressure acts on the stepped surface formed by the large diameter section 27 and the small diameter section 26 of the valve core 28, thereby pushing the valve core 28 to overcome the magnetic field force and axially displace to the second position. At this time, the first oil channel 25 is connected with the second overflow hole 14, and the oil in the first oil channel 25 enters the oil unloading channel 15 through the second overflow hole 14. After entering the oil unloading channel 15, it flows through the oil unloading pipe 24, the fourth one-way valve 22 and the fourth oil circuit 21 in sequence and enters the rod chamber.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0051] Reference numerals list

[0052] 1: piston assembly; 11: control oil chamber; 12: first one-way valve; 13: first overflow hole; 14: second overflow hole; 15: oil unloading channel; 16: second oil circuit; 17: second one-way valve; 18: third one-way valve; 19: second overflow channel; 20: third oil circuit; 21: fourth oil circuit; 22: fourth one-way valve; 23: overflow block; 24: oil unloading pipe; 25: first oil channel; 26: small diameter section; 27: large diameter section; 28: valve core; 29: first overflow channel.

Claims

1. A shock absorber, comprising a cylinder and a piston assembly (1), wherein the piston assembly (1) divides the cylinder into a rod chamber and a rodless chamber, and the piston assembly (1) is provided with a control oil chamber (11), an overflow block (23), a valve core (28), an oil discharge channel (15), and an oil discharge pipe (24); wherein: The valve core (28) is provided with a large diameter section (27) and a small diameter section (26) in sequence along its axial direction, and the diameter of the large diameter section (27) is larger than the diameter of the small diameter section (26); The overflow block (23) is an annular structure with a hollow portion, the valve core (28) is axially displaceably arranged in the hollow portion of the overflow block (23), and a first oil passage (25) is formed between the small diameter section (26) and the side wall of the hollow portion, a first overflow hole (13) communicating with both the first oil passage (25) and the control oil chamber (11) is arranged on the side wall of the overflow block (23), and a second overflow hole (14) communicating with the oil unloading passage (15) is also arranged on the side wall of the overflow block (23); wherein, The valve core (28) can be switched between a first position and a second position along the axial direction. When in the first position, the large diameter section (27) of the valve core (28) separates the first oil passage (25) and the second overflow hole (14). When in the second position, the first oil passage (25) is connected to the second overflow hole (14). The interior of the valve core (28) includes a hollow structure extending in the axial direction, the oil unloading pipe (24) is arranged in the hollow structure of the valve core (28), and the oil unloading pipe (24) partially extends out of the valve core (28) and is arranged in the overflow block (23), the oil unloading pipe (24) is respectively connected to the oil unloading channel (15) and the rodless chamber, and is used to guide the oil in the oil unloading channel (15) into the rodless chamber; One end of the valve core (28) relatively away from the large diameter section (27) is in sealing cooperation with the side wall of the hollow portion of the overflow block (23); when the valve core (28) is located between the first position and the second position, the lower end of the valve core (28), the side wall of the hollow portion of the overflow block (23) and the outer wall of the oil unloading pipe (24) together form a sealed cavity; The piston assembly (1) is provided with a second overflow channel (19) communicating with the sealing chamber and the rodless chamber.

2. The shock absorber according to claim 1, wherein: The hollow portion of the overflow block (23) includes a first hollow portion, a second hollow portion and a third hollow portion in sequence along the axial direction, the diameter of the first hollow portion is greater than the diameter of the second hollow portion, the diameter of the second hollow portion is greater than the diameter of the third hollow portion; and, The first hollow portion is in sealing cooperation with the large diameter section (27) of the valve core (28), the second hollow portion is in sealing cooperation with an end of the valve core (28) relatively away from the large diameter section (27), and the third hollow portion is in sealing cooperation with the oil unloading pipe (24).

3. The shock absorber according to claim 1, wherein: The second overflow holes (14) are arranged in plurality and are evenly distributed along the circumference of the overflow block (23).

4. The shock absorber according to claim 1, wherein: A first overflow channel (29) is provided in the piston assembly (1), and the first overflow channel (29) connects the rod chamber and the rodless chamber.

5. The shock absorber according to claim 1, wherein: The valve core (28) is arranged at the axial center position of the piston assembly (1).

6. The shock absorber according to claim 1, wherein: The oil unloading pipe (24) and the overflow block (23) are relatively fixed, and the oil unloading pipe (24) and the valve core (28) can slide relatively.

7. The shock absorber according to any one of claims 1 to 6, wherein: The piston assembly (1) is provided with a first oil circuit, a second oil circuit (16), a third oil circuit (20) and a fourth oil circuit (21); wherein: One end of the first oil circuit and the second oil circuit (16) are connected to the rod chamber, the other end of the first oil circuit is connected to the control oil chamber (11), and the other end of the second oil circuit (16) is connected to the oil unloading channel (15); one end of the third oil circuit (20) and the fourth oil circuit (21) are connected to the rodless chamber, the other end of the third oil circuit (20) is connected to the control oil chamber (11), and the other end of the fourth oil circuit (21) is connected to the oil unloading pipe (24).

8. The shock absorber according to claim 7, wherein: The valve comprises a first one-way valve (12) and a third one-way valve (18), and the piston assembly (1) further comprises a second one-way valve (17) and a fourth one-way valve (22), wherein the first one-way valve (12), the second one-way valve (17), the third one-way valve (18) and the fourth one-way valve (22) are respectively arranged in a one-to-one correspondence with the first oil circuit, the second oil circuit (16), the third oil circuit (20) and the fourth oil circuit (21); When the oil pressure in the rod chamber is greater than the oil pressure in the control oil chamber (11), and the oil pressure in the control oil chamber (11) is greater than the oil pressure in the rodless chamber, the first one-way valve (12) and the fourth one-way valve (22) are connected; when the oil pressure in the rodless chamber is greater than the oil pressure in the control oil chamber (11), and the oil pressure in the control oil chamber (11) is greater than the oil pressure in the rod chamber, the third one-way valve (18) and the second one-way valve (17) are connected.

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