Bidirectional sealing structure for linear oil cylinder

Abstract

The utility model relates to a bidirectional sealing structure for linear oil cylinder, including oil cylinder casing, the inside of oil cylinder casing is equipped with the piston bearing casing, the inside of piston bearing casing can link with piston body with the sliding, be equipped with the first annular groove on piston body or piston bearing casing, the inside of first annular groove is equipped with the T-shaped sealing ring of cross section is T, the both sides of T-shaped sealing ring in first annular groove still are equipped with annular sealing baffle, T-shaped sealing ring can be deformed to the direction of sealing baffle when being extruded by hydraulic oil to block the hydraulic oil in the inside of piston bearing casing from the lateral wall of piston body, the utility model discloses a combined seal piece that T-shaped sealing ring and sealing baffle constitute, has guaranteed that piston has adaptive, anti-extrusion and reliable dynamic sealing effect in bidirectional movement.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic cylinder technology, and specifically to a bidirectional sealing structure for linear hydraulic cylinders. Background Technology

[0002] Linear cylinders, as core actuators in hydraulic systems, achieve linear reciprocating motion by converting hydraulic energy into mechanical energy. Their working principle is based on Pascal's Law, where the output force is proportional to the effective area of ​​the piston and the pressure difference between its two ends. A typical structure includes a cylinder barrel, piston, piston rod, and sealing components. The cylinder barrel, as a pressure vessel, requires high strength, while the piston rod needs precision grinding to ensure motion accuracy. Compared to rotary motors, linear cylinders feature smaller transmission backlash and higher motion smoothness, and are widely used in engineering machinery, machine tools, and other fields.

[0003] The patent application number CN119554286B discloses a hydraulic cylinder with high buffering performance. According to its specification and drawings, the cylinder barrel is equipped with a sealing piston, and the piston rod body is set inside the sealing piston. The sealing ring improves the sealing between the piston rod body and the front end cover to prevent hydraulic oil leakage.

[0004] However, the sealing rings used in this solution have certain limitations: 1. Traditional annular sealing rings cannot effectively seal under low-pressure and high-pressure conditions; 2. Traditional annular sealing rings have a high coefficient of friction, a short lifespan, and cannot provide good smoothness during the sealing process. Summary of the Invention

[0005] This invention addresses the aforementioned deficiencies in piston sealing in linear hydraulic cylinders by proposing a bidirectional sealing structure. This structure achieves high integration of the hydraulic circuit while ensuring a self-adaptive, anti-extrusion, and reliable dynamic sealing effect for the piston during bidirectional movement, significantly improving the working stability and service life of the hydraulic cylinder.

[0006] The objective of this invention is achieved through the following technical solution: a bidirectional sealing structure for a linear hydraulic cylinder, comprising a cylinder housing, a piston bearing housing inside the cylinder housing, a piston body slidably connected inside the piston bearing housing, a first annular groove on the piston body or piston bearing housing, a T-shaped sealing ring with a T-shaped cross-section inside the first annular groove, and annular sealing retaining rings on both sides of the T-shaped sealing ring inside the first annular groove. When the T-shaped sealing ring is squeezed by hydraulic oil, it can deform in the direction of the sealing retaining ring, thereby preventing the hydraulic oil inside the piston bearing housing from flowing out from the side wall of the piston body.

[0007] Preferably, the T-shaped sealing ring includes an integrally connected protrusion and a base, and sealing retaining rings are provided on both sides of the protrusion in the first annular groove, with the inner wall of each sealing retaining ring conforming to the surface of the base. This design achieves functional separation and synergy between sealing and support. The "protruding" part of the T-shaped sealing ring is easily deformed under pressure to tightly fit the gap; while the "base" provides a stable mounting foundation for the whole and serves as the support surface for the sealing ring; the sealing rings on both sides clamp the base from the root, effectively limiting the overall axial displacement and root twisting of the T-shaped sealing ring under high pressure, thereby greatly improving the reliability and service life of the seal under high pressure conditions.

[0008] Preferably, the T-shaped sealing ring is made of nitrile rubber, the sealing retainer is made of polytetrafluoroethylene, and the elastic modulus of the sealing retainer is greater than that of the T-shaped sealing ring.

[0009] Preferably, the piston body includes a piston rod and a piston plate, the piston rod is connected to the middle of the piston plate, and the piston bearing housing is provided with a first annular inner groove and a second annular inner groove with different diameters. The piston rod and the piston plate are respectively coaxially connected inside the first annular inner groove and the second annular inner groove.

[0010] Preferably, both the piston bearing housing and the piston plate are provided with a first annular groove, and each first annular groove is provided with a T-shaped sealing ring and several sealing retaining rings inside.

[0011] Preferably, the piston plate separates the interior of the piston bearing housing into a first cavity and a second cavity. The piston bearing housing has a first oil flow channel and a second oil flow channel that are not interconnected. The oil ports at both ends of the first oil flow channel are respectively connected to the interior of the cylinder housing and the interior of the first cavity. The oil ports at both ends of the second oil flow channel are respectively connected to the interior of the cylinder housing and the interior of the second cavity. The change in the volume of oil in the first cavity and the second cavity can drive the piston body to slide.

[0012] Preferably, the piston bearing housing extends into the cylinder housing from the side away from the piston body and is provided with an oil passage guide column. The cylinder housing is provided with a plurality of second annular grooves located on the side wall of the oil passage guide column. Annular sealing rings are installed at intervals on the plurality of second annular grooves. At least one second annular groove without an annular sealing ring is provided with a first oil hole communicating with the cylinder housing. At least one second annular groove without an annular sealing ring is provided with a second oil hole communicating with the cylinder housing. The first oil hole and the second oil hole are not interconnected. The first oil hole is connected to the first oil flow channel, and the second oil hole is connected to the second oil flow channel. This configuration constitutes the core working principle of a compact and efficient double-acting hydraulic cylinder. Two independent cavities are formed by the piston plate and equipped with two independent oil flow channels. By controlling the oil inlet and outlet of the two cavities, the bidirectional linear motion of the piston can be precisely controlled. The double-acting mode enables the piston body to provide strong driving force in both the extension and retraction directions, resulting in high working efficiency.

[0013] Preferably, the cylinder housing is provided with a third oil hole and a fourth oil hole respectively connected to the first oil hole and the second oil hole, the third oil hole of the second oil hole is connected to the external oil tank, and the cylinder housing and the piston bearing housing are sealed together by an annular sealing ring. This design clearly defines the third and fourth oil holes as standard external interfaces for the cylinder, defines the direction of oil inlet and outlet, facilitates connection with external hydraulic system pipelines, and establishes a complete, smooth, and sealed oil transmission path from the external oil port to the cylinder housing, to the oil hole on the oil passage guide column, to the piston bearing housing inner channel, and finally to the working chamber.

[0014] 1. A first annular groove is set on the piston body and piston bearing housing, and a T-shaped sealing ring and two sealing retainer rings are installed inside, forming a unique bidirectional dynamic sealing mechanism. The T-shaped sealing ring is made of nitrile rubber, which has high elasticity and can deform under hydraulic oil pressure to actively fill and fit the sealing surface. The sealing retainer rings are made of polytetrafluoroethylene, which has a higher elastic modulus than the T-shaped sealing ring, providing rigid support and preventing the T-shaped sealing ring from being squeezed out of the gap under high pressure. When the piston body moves in a different direction, the hydraulic oil pressure changes accordingly, driving the protrusion of the T-shaped sealing ring to deform to the corresponding side, always achieving radial sealing. This adaptive bidirectional sealing mechanism avoids the complexity of traditional sealing components that require multiple unidirectional sealing rings to be stacked, achieving efficient sealing in a limited space and reducing friction loss and the risk of sealing failure. 2. The nitrile rubber material of the T-shaped seal ring provides excellent elasticity and resilience, ensuring that it can return to its original shape after the hydraulic oil pressure is released and adapt to reciprocating motion; the PTFE material of the sealing ring provides the necessary rigid support. The first annular groove compactly integrates a T-shaped seal ring and two sealing rings, realizing multi-stage sealing in a small space, reducing the number of parts and reducing assembly complexity. 3. The oil passage guide column extends into the cylinder housing and is sealed and separated by multiple second annular grooves and annular sealing rings. The first oil hole and the second oil hole are respectively connected to the first oil flow channel and the second oil flow channel. This design integrates the oil inlet and outlet functions into a single oil passage guide column, which simplifies the oil passage layout, reduces external pipelines and connection points, and reduces the risk of oil leakage. This integrated oil passage design avoids the complexity and installation difficulties caused by the cross of multiple oil pipes in traditional oil cylinders, reflecting space optimization and improved system reliability. Attached Figure Description

[0015] Figure 1 This is a perspective view of the present utility model; Figure 2 This is a cross-sectional view of the present invention located in the first oil flow channel region; Figure 3 This is a cross-sectional view of the present invention after the T-shaped sealing ring and the sealing retaining ring have been removed; Figure 4 This is a schematic diagram showing the installation between the T-shaped sealing ring and the sealing retaining ring of this utility model; Figure 5 For the present utility model in Figure 3 Enlarged view of region A in the image; Figure 6 This is a cross-sectional view of the second oil flow channel region of this utility model; Figure 7 For the present utility model in Figure 6 A magnified view of region B in the image.

[0016] The markings in the diagram are as follows: 1. Cylinder housing; 10. Second annular groove; 101. Annular sealing ring; 11. Third oil hole; 12. Fourth oil hole; 2. Piston bearing housing; 21. First cavity; 22. Second cavity; 23. First oil flow channel; 24. Second oil flow channel; 25. Oil passage guide column; 27. First oil hole; 28. Second oil hole; 3. Piston body; 31. Piston rod; 32. Piston plate; 4. First annular groove; 5. T-shaped sealing ring; 51. Protrusion; 52. Base; 6. Sealing retainer ring. Detailed Implementation

[0017] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings: like Figure 1 and Figure 2 As shown, a bidirectional sealing structure for a linear hydraulic cylinder includes a cylinder housing 1, inside which a piston bearing housing 2 is provided, and a piston body 3 is slidably connected inside the piston bearing housing 2; the left end of the piston body 3 passes through the inside of the piston bearing housing 2, so when the piston body 3 slides relative to the inside of the piston bearing housing 2, it can drive external components to move.

[0018] Please continue to refer to the reference. Figure 3The piston body 3 includes a piston rod 31 and a piston plate 32. The piston rod 31 is cylindrical in shape, and the piston plate 32 is circular in shape. The piston rod 31 is connected to the middle of the piston plate 32, and the connection between the piston rod 31 and the piston plate 32 is sealed. The piston bearing housing 2 is provided with a first annular inner groove and a second annular inner groove with different diameters. The piston rod 31 and the piston plate 32 are coaxially connected inside the first annular inner groove and the second annular inner groove, respectively. like Figure 2 As shown, since the diameter of the piston plate 32 is larger than the diameter of the piston rod 31, the piston plate 32 can provide a larger force-bearing area during the sliding process inside the second annular inner groove, thereby providing effective support force, and the piston body 3 can slide smoothly inside the piston bearing housing 2.

[0019] Please continue to refer to this. Figure 2 , Figure 5 , Figure 6 and Figure 7 The piston plate 32 separates the interior of the piston bearing housing 2 into a first cavity 21 and a second cavity 22. The piston bearing housing 2 has a first oil flow channel 23 and a second oil flow channel 24 that are not interconnected. The oil ports at both ends of the first oil flow channel 23 are respectively connected to the interior of the cylinder housing 1 and the interior of the first cavity 21. The oil ports at both ends of the second oil flow channel 24 are respectively connected to the interior of the cylinder housing 1 and the interior of the second cavity 22. With this configuration, when hydraulic oil is filled into the first oil flow channel 23 through the oil passage inside the cylinder housing 1, the volume of the first cavity 21 will continuously increase, while the volume of the second cavity 22 will continuously decrease. The hydraulic oil in the second cavity 22 flows back into the cylinder housing 1 through the second oil flow channel 24. The change in the volume of oil in the first cavity 21 and the second cavity 22 can push the piston body 3 to slide. The piston bearing housing 2 extends into the cylinder housing 1 from the side away from the piston body 3 and is provided with an oil passage guide column 25. The cylinder housing 1 is provided with a plurality of second annular grooves 10 located on the side wall of the oil passage guide column 25. Annular sealing rings 101 are installed at intervals on the plurality of second annular grooves 10. At least one second annular groove 10 without an annular sealing ring 101 is provided with a first oil hole 27 communicating with the cylinder housing 1. At least one second annular groove 10 without an annular sealing ring 101 is provided with a second oil hole 28 communicating with the cylinder housing 1. The first oil hole 27 and the second oil hole 28 are not interconnected. The first oil hole 27 is connected to the first oil flow channel 23, and the second oil hole 28 is connected to the second oil flow channel 24.

[0020] The cylinder housing 1 is provided with a third oil hole 11 and a fourth oil hole 12 respectively connected to the first oil hole 27 and the second oil hole 28. The third oil hole 11 of the second oil hole 28 is connected to the external oil tank. The cylinder housing 1 and the piston bearing housing 2 are sealed together by an annular sealing ring 101. When the volume of the first cavity 21 needs to be increased, the external oil tank supplies hydraulic oil to the first oil hole 27 through the third oil hole 11 until the hydraulic oil accumulates inside one of the second annular grooves 10. At this time, the hydraulic oil in the second annular groove 10 flows through the first oil hole 27 to the inside of the first oil flow channel 23, causing the volume of the first cavity 21 to continuously increase. The hydraulic oil in the first cavity 21 will continuously push the piston body 3 to slide in one direction relative to the inside of the piston bearing housing 2. The hydraulic oil in the second cavity 22 flows back to the inside of the cylinder housing 1 from the second oil flow channel 24, and the volume of the second cavity 22 continuously decreases. When it is necessary to increase the volume of the second cavity 22, the external oil tank supplies hydraulic oil to the second oil hole 28 through the fourth oil hole 12 until the hydraulic oil accumulates inside another second annular groove 10; at this time, the hydraulic oil in the second annular groove 10 flows through the second oil hole 28 to the inside of the second oil flow channel 24, so that the volume of the second cavity 22 will continuously increase, and the hydraulic oil in the second cavity 22 will continuously push the piston body 3 to slide in another direction relative to the inside of the piston bearing housing 2; the hydraulic oil in the first cavity 21 flows back to the inside of the cylinder housing 1 from the first oil flow channel 23, and the volume of the first cavity 21 continuously decreases; When either the first oil flow channel 23 or the second oil flow channel 24 is in the oil inlet state, the other flow channel is in the oil outlet state. This ensures that the first oil flow channel 23 and the second oil flow channel 24 not only handle oil inlet to the piston bearing housing 2, but also oil outlet to the piston bearing housing 2. The oil inlet and outlet of the first oil flow channel 23 and the second oil flow channel 24 in the cylinder housing 1 are both integrated on the oil circuit guide column 25, which is beneficial to the integration of the entire hydraulic cylinder oil circuit.

[0021] Please continue to refer to this. Figure 2 Both the piston body 3 and the piston bearing housing 2 are provided with a first annular groove 4. The first annular groove 4 is provided with a T-shaped sealing ring 5 with a T-shaped cross-section. The first annular groove 4 is also provided with annular sealing rings 6 on both sides of the T-shaped sealing ring 5. The T-shaped sealing ring 5 is made of nitrile rubber, and the sealing ring 6 is made of tetrafluoroethylene. The elastic modulus of the sealing ring 6 is greater than that of the T-shaped sealing ring 5. During implementation, when the T-shaped sealing ring 5 is squeezed by hydraulic oil, it can deform in the direction of the sealing ring 6, thereby preventing the hydraulic oil inside the piston bearing housing 2 from flowing out from the side wall of the piston body 3; the first annular groove 4 occupies a small space, and a T-shaped sealing ring 5 and two sealing rings 6 are integrated and installed in a small space to achieve a sealing effect, which reflects the characteristics of integration. The T-shaped sealing ring 5 deforms to achieve a seal; its purpose is to actively fill and conform to the sealing surface by changing its shape. The sealing retainer ring 6 deforms to provide support, thus protecting the T-shaped sealing ring 5 from being squeezed out. The pressure generated by the hydraulic oil inside the piston bearing housing 2 axially compresses the T-shaped sealing ring 5 towards the root of the gap between the retainer ring, the piston body 3, and the piston bearing housing 2. The sealing retainer ring 6 will bear enormous stress near the edge of the gap. The T-shaped sealing ring 5 is made of nitrile rubber, which gives it excellent elasticity. After depressurization, it can basically completely return to its original shape, preparing it for the next sealing cycle. The sealing ring 6 is made of PTFE. The elastic modulus of the sealing ring 6 is greater than that of the T-shaped sealing ring 5, making the sealing ring 6 rigid compared to the T-shaped sealing ring 5. However, the sealing ring 6 is flexible compared to the piston body 3 and the piston bearing housing 2. The sealing ring 6 can undergo a certain degree of elastic compression at the microscopic level.

[0022] Please continue to refer to the reference. Figure 4 The T-shaped sealing ring 5 includes an integrally connected protrusion 51 and a base 52. Sealing retaining rings 6 are provided on both sides of the protrusion 51 in the first annular groove 4. The inner wall of each sealing retaining ring 6 is attached to the surface of the base 52. The piston bearing housing 2 and the piston plate 32 are both provided with a first annular groove 4. Each first annular groove 4 is provided with a T-shaped sealing ring 5 and several sealing retaining rings 6 inside. Please refer to the reference. Figure 2 and Figure 4 The direction of movement of the piston body 3 directly determines the direction of force application of the hydraulic oil, thereby driving the dynamic deformation process of the T-shaped seal ring 5.

[0023] like Figure 2 As shown, when the piston body 3 moves to the right: the hydraulic oil pressure in the first chamber 21 increases, and the pressure acts on the left side of the protrusion 51 on the T-shaped seal ring 5. Under the hydraulic pressure, the entire T-shaped seal ring 5 is pushed to the right and axially compressed in the direction of the piston body 3's movement until the T-shaped seal ring 5, made of soft nitrile rubber, expands radially under the pressure of the medium. Meanwhile, the sealing ring 6 on the left side of the protrusion 51 on the T-shaped sealing ring 5 becomes the force support point. The sealing ring 6 bears the huge axial thrust and extrusion force from the T-shaped sealing ring 5. Due to its relative rigidity, the sealing ring 6 undergoes slight elastic deformation. The sealing ring 6 plays a supporting role when the T-shaped sealing ring 5 is deformed under the action of high pressure oil. The deformation of the protrusion 51 of the T-shaped sealing ring 5 tightly adheres to and fills the inner wall of the piston bearing housing 2 and the side of the first annular groove 4 near the second cavity 22, forming a dynamic seal between the first cavity 21 and the second cavity 22. When the piston body 3 moves to the left in the opposite direction: the principle is exactly the same, but the direction is reversed. At this time, the oil pressure in the second chamber 22 increases, and the T-shaped sealing ring 5 is pushed to the left, its deformation trajectory being mirror-symmetrical to the above process. The left-side sealing ring 6 also provides rigid support at this time, bearing the pressure and protecting the sealing ring.

[0024] The deformation of the T-shaped seal ring 5 is actively adjusted by the direction of the hydraulic oil, and it generates reciprocating elastic deformation during the change of hydraulic oil pressure direction. When the piston body 3 is subjected to the first chamber 21 or the second chamber 22 to change the direction of movement each time, the compression direction of the T-shaped seal ring 5 will change accordingly, but the seal is always achieved through radial expansion.

[0025] The working principle and usage method of this utility model.

[0026] by Figure 2 Based on the position and orientation, the piston plate 32 divides the interior of the piston-bearing housing 2 into a first cavity 21 and a second cavity 22 that are not connected to each other.

[0027] When hydraulic oil enters the first chamber 21 through the first oil flow channel 23, the oil pressure acts on the left side of the piston plate 32, pushing the piston body 3 to move to the right. At this time, the volume of the second chamber 22 is compressed, and the hydraulic oil inside is discharged through the second oil flow channel 24.

[0028] When hydraulic oil enters the second chamber 22 through the second oil flow channel 24, the oil pressure acts on the right side of the piston plate 32, pushing the piston body 3 to move to the left, and the hydraulic oil in the first chamber 21 is discharged through the first oil flow channel 23.

[0029] The piston rod 31 transmits the linear motion of the piston body 3 to external components, thereby performing the work.

[0030] Hydraulic oil is supplied from an external oil pipe to the third oil hole 11 or the fourth oil hole 12 on the cylinder housing 1.

[0031] The oil is distributed through the annular channel on the oil guide column 25. Specifically, the oil leading to the third oil hole 11 enters the first oil hole 27 and then flows into the first oil flow channel 23; the oil leading to the fourth oil hole 12 enters the second oil hole 28 and then flows into the second oil flow channel 24.

[0032] The multiple second annular grooves 10 on the outer wall of the oil passage guide column 25 and the annular sealing rings 101 installed therein ensure effective isolation between the first oil hole 27 and the second oil hole 28, prevent oil passage cross-connection, and realize the high integration of oil inlet and return functions on a single component.

[0033] When the piston body 3 moves to the right: the pressure in the first chamber 21 increases, and the high-pressure oil acts on the left side of the T-shaped seal ring 5, pushing it to move slightly to the right and squeezing the right-side sealing ring 6. Under the action of oil pressure, the protrusion 51 of the T-shaped seal ring 5 undergoes radial elastic deformation, fitting more tightly against the sealing surface and preventing oil from leaking from the first chamber 21 to the second chamber 22. At this time, the right-side sealing ring 6 provides rigid support, preventing the T-shaped seal ring 5 from being squeezed into the gap.

[0034] When the piston body 3 moves to the left: the pressure in the second chamber 22 increases, and the process is the opposite of the above. The high-pressure oil pushes the T-shaped sealing ring 5 to the left, and the sealing ring 6 on the left side provides support. The radial deformation of the protrusion 51 achieves reverse sealing.

[0035] The nitrile rubber T-ring 5 ensures good elasticity and resilience, while the PTFE sealing ring 6 provides the necessary anti-extrusion support. This combination achieves a reliable bidirectional seal that adapts to the direction of pressure.

[0036] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. A bidirectional sealing structure for a linear hydraulic cylinder, comprising a cylinder housing (1), characterized in that, The cylinder housing (1) is provided with a piston support housing (2) inside. The piston support housing (2) is slidably connected to a piston body (3). The piston body (3) or the piston support housing (2) is provided with a first annular groove (4). The first annular groove (4) is provided with a T-shaped sealing ring (5) with a T-shaped cross-section inside. The first annular groove (4) is also provided with annular sealing rings (6) on both sides of the T-shaped sealing ring (5). When the T-shaped sealing ring (5) is squeezed by hydraulic oil, it can deform in the direction of the sealing ring (6) to prevent the hydraulic oil inside the piston support housing (2) from flowing out from the side wall of the piston body (3).

2. The bidirectional sealing structure of the linear hydraulic cylinder according to claim 1, characterized in that, The T-shaped sealing ring (5) includes an integrally connected protrusion (51) and a base (52). A sealing retainer ring (6) is provided on both sides of the protrusion (51) in the first annular groove (4). The inner wall of each sealing retainer ring (6) is attached to the surface of the base (52).

3. The bidirectional sealing structure of the linear hydraulic cylinder according to claim 2, characterized in that, The T-shaped sealing ring (5) is made of nitrile rubber, and the sealing retainer ring (6) is made of tetrafluoroethylene. The elastic modulus of the sealing retainer ring (6) is greater than that of the T-shaped sealing ring (5).

4. The bidirectional sealing structure of the linear hydraulic cylinder according to claim 3, characterized in that, The piston body (3) includes a piston rod (31) and a piston plate (32). The piston rod (31) is connected to the middle of the piston plate (32). The piston bearing housing (2) is provided with a first annular inner groove and a second annular inner groove with different diameters. The piston rod (31) and the piston plate (32) are coaxially connected inside the first annular inner groove and the second annular inner groove, respectively.

5. The bidirectional sealing structure of the linear hydraulic cylinder according to claim 4, characterized in that, The piston bearing housing (2) and piston plate (32) are both provided with a first annular groove (4), and each first annular groove (4) is provided with a T-shaped sealing ring (5) and several sealing retaining rings (6).

6. The bidirectional sealing structure of the linear hydraulic cylinder according to claim 5, characterized in that, The piston plate (32) separates the interior of the piston bearing housing (2) into a first cavity (21) and a second cavity (22). The piston bearing housing (2) has a first oil flow channel (23) and a second oil flow channel (24) that are not interconnected. The oil ports at both ends of the first oil flow channel (23) are respectively connected to the interior of the cylinder housing (1) and the interior of the first cavity (21). The oil ports at both ends of the second oil flow channel (24) are respectively connected to the interior of the cylinder housing (1) and the interior of the second cavity (22). The change in the volume of oil in the first cavity (21) and the second cavity (22) can push the piston body (3) to slide.

7. The bidirectional sealing structure of the linear hydraulic cylinder according to claim 6, characterized in that, The piston bearing housing (2) extends into the cylinder housing (1) from the side away from the piston body (3) and is provided with an oil passage guide column (25). The cylinder housing (1) is provided with a plurality of second annular grooves (10) located on the side wall of the oil passage guide column (25). Annular sealing rings (101) are installed at intervals on the plurality of second annular grooves (10). At least one second annular groove (10) without an annular sealing ring (101) is provided with a first oil hole (27) communicating with the cylinder housing (1). At least one second annular groove (10) without an annular sealing ring (101) is provided with a second oil hole (28) communicating with the cylinder housing (1). The first oil hole (27) and the second oil hole (28) are not connected to each other. The first oil hole (27) is connected to the first oil flow channel (23), and the second oil hole (28) is connected to the second oil flow channel (24).

8. The bidirectional sealing structure of the linear hydraulic cylinder according to claim 7, characterized in that, The cylinder housing (1) is provided with a third oil hole (11) and a fourth oil hole (12) respectively connected to the first oil hole (27) and the second oil hole (28). The third oil hole (11) of the second oil hole (28) is connected to the external oil tank. The cylinder housing (1) and the piston bearing housing (2) are sealed by an annular sealing ring (101).

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