Hydraulic cylinder convenient to maintain and hydraulic hoist applying hydraulic cylinder

Abstract

The invention relates to the technical field of hydraulic cylinders, and discloses a hydraulic cylinder convenient to maintain and a hydraulic hoist applying the hydraulic cylinder The hydraulic cylinder convenient to maintain comprises a hydraulic assembly, and the hydraulic assembly comprises a cylinder body, a piston block arranged in the cylinder body, a piston rod fixedly connected with the piston block and an oil injection hole formed in the cylinder body. The sealing mechanism is arranged on the cylinder body, the sealing mechanism comprises a sealing seat fixedly installed at the right end of the cylinder body, the sealing seat is connected to the surface of the piston rod in a sleeving mode, a first annular groove and a second annular groove are sequentially formed in the sealing seat from left to right, and a sealing kit is arranged in the first annular groove and comprises an inwards-concave section and a protruding section. The deformation constraint of the sealing kit is automatically released through the movement of the piston rod, so that the inner concave section is actively attached to the surface of the piston rod under the high-pressure action of hydraulic oil, the inner concave section, the convex section and the sealing ring jointly form an M-shaped double-layer sealing structure, and therefore the hydraulic oil is effectively prevented from leaking to the outside.

Description

Technical Field

[0001] This invention relates to the field of hydraulic cylinder technology, and more particularly to a hydraulic cylinder that is easy to maintain and a hydraulic gate opener using the same hydraulic cylinder. Background Technology

[0002] In modern industrial production and the operation of large-scale engineering equipment, high-pressure, high-flow hydraulic components and hydraulic systems play a vital role. Hydraulic cylinders, as key hydraulic actuators that achieve linear reciprocating motion, are widely used in various mechanical equipment. Hydraulic cylinders convert hydraulic energy into mechanical energy, providing power for equipment operation.

[0003] A self-locking hydraulic cylinder disclosed in CN116292494A includes a first cylinder, a second cylinder, a telescopic assembly, and a fixed assembly. The second cylinder is fixedly connected to the left side of the first cylinder. A telescopic assembly connects the first and second cylinders. A fixed assembly is connected to the second cylinder. The fixed assembly is connected to the telescopic assembly. The telescopic assembly includes a rod, a piston, a limiting block, a first pipe, a second pipe, a first sealing plug, a first sealing ring, a first circular ring, a second sealing ring, a buffer unit, a first collection unit, and a heat dissipation unit. Although the above technical solution can convert the piston's kinetic energy into heat energy through the relative friction between the first and second arc-shaped blocks, avoiding the piston impacting the hydraulic cylinder head due to excessive kinetic energy, it has the advantage of improving the service life of the hydraulic cylinder.

[0004] Currently, traditional hydraulic cylinder sealing structures often employ a single static sealing ring (such as an O-ring or Y-ring) for sealing. This sealing ring needs to maintain a tight seal with the piston rod surface for an extended period to effectively prevent hydraulic oil leakage. However, in practical applications, with increased usage time, the sealing ring is constantly exposed to high pressure, repeatedly subjected to the impact of hydraulic oil, and continuously rubbed against the high-speed moving piston rod. Coupled with frequent temperature changes, it is prone to deformation, aging, and wear, leading to a significant decrease in preload. Under dynamic conditions where the piston rod moves outward, the system pressure rises sharply, causing gaps between the piston rod and the sealing ring due to pressure changes and wear. A single sealing ring cannot automatically adjust the sealing state or compensate for the gaps in real time based on the piston rod's movement and pressure changes. During the piston rod extension phase, hydraulic oil, under high pressure, easily leaks through these gaps, leading to seal failure and affecting the normal operation of the hydraulic cylinder. Summary of the Invention

[0005] The purpose of this invention is to provide a hydraulic cylinder that is easy to maintain and a hydraulic gate opener that uses the hydraulic cylinder, so as to solve the problem mentioned in the background art that the single static seal ring in the traditional hydraulic cylinder is deformed, aged and worn due to high pressure, friction and temperature changes, resulting in a decrease in preload.

[0006] The present invention provides a hydraulic cylinder that is easy to maintain and a hydraulic gate opener using the hydraulic cylinder, which adopts the following technical solution: A maintenance-friendly hydraulic cylinder, comprising: The hydraulic assembly includes a cylinder body, a piston block disposed within the cylinder body, a piston rod fixedly connected to the piston block, and an oil injection port disposed on the cylinder body, and further includes: A sealing mechanism is provided on the cylinder body. The sealing mechanism includes a sealing seat fixedly installed on the right end of the cylinder body. The sealing seat is sleeved on the surface of the piston rod. The sealing seat has a first annular groove and a second annular groove opened from left to right. A sealing kit is provided in the first annular groove. The sealing kit includes a concave section and a convex section. The convex section is symmetrically arranged on both sides of the concave section. A sealing ring is fixedly connected to the side of the convex section away from the concave section. The sealing ring is fixed in the first annular groove, and the inner side of the sealing ring is in contact with the surface of the piston rod. The outer surface of the concave section is equidistantly distributed with multiple sets of abutment blocks along the circumferential direction. A connecting rod is fixedly connected to the abutment block, and a rope is fixedly connected to the connecting rod. The concave section is controlled to move closer to or away from the piston rod by the rope.

[0007] Furthermore, the second annular groove is provided with triggering mechanisms that correspond one-to-one with the rope at equal intervals along the circumferential direction. The triggering mechanism includes a bracket fixedly connected in the second annular groove and a shaft rotatably mounted on the bracket. The other end of the rope extends into the second annular groove and is wound around the shaft. The rope is wound up and unwound by controlling the rotation of the shaft.

[0008] Furthermore, a small gear is fixedly connected to the shaft, a large gear meshes with one side of the small gear, a central shaft is fixedly connected to the large gear, the central shaft is rotatably mounted on the bracket, a sector wheel is fixedly connected to the central shaft, and a friction pad is provided on the side of the sector wheel that contacts the piston rod surface. The piston rod moves outward to control the sector wheel to flip, causing the shaft to unwind the rope and release the deformation constraint on the concave section.

[0009] Furthermore, the sealing seat is provided with a cleaning mechanism, which includes a fixing ring fixedly connected to the sealing seat and multiple sets of spring plates equidistantly arranged along the circumference of the fixing ring. Each spring plate has a brush on its inner side at the end away from the sealing seat.

[0010] Furthermore, the cleaning mechanism also includes a collar that is slidably sleeved on the outer surface of the fixed ring. Multiple sets of rack plates are fixedly connected to the collar along the circumferential direction. The rack plates extend into the second annular groove and mesh with the corresponding large gear.

[0011] Furthermore, the inner side of the collar consists of a horizontal section and an inclined section from left to right. When the inclined section is in contact with the outer surface of the spring plate, the spring plate is in an inclined state and the brush is away from the piston rod surface. When the horizontal section is in contact with the outer surface of the spring plate, the spring plate is in a horizontal state and the brush is in contact with the piston rod surface.

[0012] Furthermore, a torsion spring is provided on the shaft, with both ends of the torsion spring fixedly connected to the bracket and the pinion, respectively.

[0013] Furthermore, guide wheels corresponding to the rope are equidistantly arranged along the circumferential direction in the second annular groove, and the rope slides in contact with the guide wheels.

[0014] Furthermore, the retaining ring is sleeved on the surface of the piston rod, and there is a gap between the inner side of the retaining ring and the surface of the piston rod.

[0015] A hydraulic gate opener using the hydraulic cylinder includes a frame, the cylinder body is hinged to the frame, and a gate is hinged to the end of the piston rod. The gate is used to open and close the passage set on the frame.

[0016] The beneficial effects of this invention are: By setting up a sealing mechanism and a triggering mechanism, when the piston rod extends outward, the triggering mechanism automatically releases the deformation constraint of the sealing kit through the movement of the piston rod. This allows the concave section to actively conform to the piston rod surface under the high pressure of hydraulic oil, forming an M-shaped double-layer sealing structure together with the convex section and the sealing ring. This effectively prevents hydraulic oil from leaking to the outside. When the piston rod returns to its original position, the triggering mechanism keeps the rope taut, forcing the concave section to detach from the piston rod. At this time, the sealing ring achieves a static sealing function, preventing the sealing kit from being deformed by pressure over a long period of time. The triggering mechanism can automatically control the deformation of the sealing kit according to the movement state of the piston rod, realizing real-time dynamic adjustment of the sealing state. This compensates for the gap between the piston rod and the sealing ring, effectively preventing hydraulic oil leakage under high pressure.

[0017] By setting up a cleaning mechanism, when the piston rod moves inward, the brush can be controlled to adhere to the piston rod surface through the coordination of the triggering mechanism to continuously scrape away impurities, preventing impurity particles from entering the cylinder and causing seal failure. By removing impurities attached to the piston rod surface, wear on the piston rod, sealing kit, and sealing ring can be effectively reduced, preventing piston jamming. Attached Figure Description

[0018] Figure 1 This is a front view of the hydraulic components, sealing mechanism, frame, and gate of the present invention. Figure 2 This is a three-dimensional structural diagram of the hydraulic component of the present invention; Figure 3 This is a front view of the hydraulic components and sealing mechanism of the present invention. Figure 4 This is a three-dimensional structural diagram of the piston block, piston rod, and sealing mechanism of the present invention. Figure 5 This is a front view cross-sectional diagram of the piston rod, sealing mechanism, triggering mechanism, and cleaning mechanism of the present invention. Figure 6 This is a three-dimensional cross-sectional view of the sealing kit, sealing ring, and abutment block of the present invention. Figure 7 This is a top view of the cross-sectional structure of the sealing seat of the present invention; Figure 8 For the present invention Figure 7 Enlarged schematic diagram of the structure at point A in the middle; Figure 9 This is a partial three-dimensional cross-sectional view of the sealing mechanism and triggering mechanism of the present invention; Figure 10 This is a three-dimensional cross-sectional view of the cleaning mechanism of the present invention; Figure 11 This is a three-dimensional structural diagram of the fixing ring, spring plate, brush, and collar of the present invention. Figure 12 This is a three-dimensional structural diagram of the fixing ring, spring plate, and brush of the present invention. Figure 13 This is a schematic diagram showing the front view of the concave section, convex section, sealing ring, and spring plate of the present invention.

[0019] In the picture: 100. Hydraulic assembly; 101. Cylinder body; 102. Piston block; 103. Piston rod; 104. Oil injection hole; 200. Sealing mechanism; 201. Sealing seat; 202. First annular groove; 203. Second annular groove; 204. Sealing kit; 2041. Concave section; 2042. Protruding section; 205. Sealing ring; 206. Abutment block; 207. Connecting rod; 208. Rope; 209. Guide wheel; 30. 0. Triggering mechanism; 301. Bracket; 302. Shaft; 303. Pinion; 304. Gear; 305. Central shaft; 306. Sector wheel; 307. Friction pad; 308. Torsion spring; 400. Cleaning mechanism; 401. Fixing ring; 402. Spring plate; 403. Brush; 404. Collar; 405. Horizontal section; 406. Inclined section; 407. Rack plate; 500. Frame; 600. Gate. Detailed Implementation

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0021] Reference Figures 1-3The present invention provides a hydraulic cylinder that is easy to maintain, including a hydraulic assembly 100. The hydraulic assembly 100 includes a cylinder body 101, a piston block 102 disposed in the cylinder body 101, a piston rod 103 fixedly connected to the piston block 102, and an oil injection hole 104 disposed on the cylinder body 101.

[0022] Reference Figures 3-7 It also includes a sealing mechanism 200 disposed on the cylinder body 101. Specifically, the sealing mechanism 200 includes a sealing seat 201 fixedly installed on the right end of the cylinder body 101. The sealing seat 201 is sleeved on the surface of the piston rod 103, and the piston rod 103 can move back and forth within the sealing seat 201. A first annular groove 202 and a second annular groove 203 are sequentially formed on the sealing seat 201 from left to right. A sealing kit 204 is disposed in the first annular groove 202. The sealing kit 204 includes a concave section 2041 and a convex section 2042. The sealing components 204 and 205 are symmetrically arranged on both sides of the concave section 2041 and fixedly installed with the concave section 2041. The side of the protruding section 2042 away from the concave section 2041 is fixedly connected with a sealing ring 205. The sealing ring 205 is fixed in the first annular groove 202, and the inner side of the sealing ring 205 is in contact with the surface of the piston rod 103. The sealing ring 205 is tightly fitted with the surface of the piston rod 103 to form a static seal, which can prevent hydraulic oil from leaking outward when the piston rod 103 is stationary. The sealing component 204 and the sealing ring 205 can be made of rubber.

[0023] Specifically, multiple sets of abutment blocks 206 are evenly distributed along the circumferential direction on the outer surface of the concave section 2041. The abutment blocks 206 can be 12, 14 or 16 sets. A connecting rod 207 is fixedly connected to the abutment block 206, and a rope 208 is fixedly connected to the connecting rod 207. The rope 208 controls the raising and lowering of the connecting rod 207 and the abutment block 206, so that the abutment block 206 controls the concave section 2041 to move closer to or away from the piston rod 103. When the concave section 2041 is in contact with the surface of the piston rod 103, an M-shaped double-layer seal is formed between the concave section 2041, the protruding section 2042 and the sealing ring 205.

[0024] The second annular groove 203 is provided with guide wheels 209 that correspond one-to-one with the rope 208 at equal intervals along the circumference. The rope 208 slides in contact with the guide wheels 209, and the guide wheels 209 guide the rope 208.

[0025] The sealing mechanism 200 drives the sealing kit 204 to dynamically deform via the rope 208, achieving adaptive sealing of the piston rod 103. When the piston rod 103 is in a non-working state, the rope 208 is in a taut state, the concave section 2041 is away from the piston rod 103, and the sealing ring 205 forms a static seal with the piston rod 103. When the piston rod 103 extends outward, by relaxing the rope 208, since the abutment blocks 206 are equidistantly distributed along the circumferential direction at the concave part of the outer surface of the concave section 2041, the concave section 2041, after losing the tension of the rope 208, can move closer to the surface of the piston rod 103 under its own elastic force. When the inner side of the concave section 2041 is in contact with the surface of the piston rod 103, the middle part of the concave section 2041 is recessed inward, forming an M-shaped double-layer seal with the protruding sections 2042 on both sides and the sealing ring 205, thereby effectively preventing hydraulic oil from leaking to the outside.

[0026] Reference Figure 5 , Figures 7-9 The second annular groove 203 is equidistantly provided with triggering mechanisms 300 corresponding to the ropes 208 along the circumferential direction. Each triggering mechanism 300 includes a bracket 301 fixedly connected in the second annular groove 203 and a shaft 302 rotatably mounted on the bracket 301. The other end of the rope 208 extends into the second annular groove 203 and is wound around the shaft 302. The other end of the rope 208 is fixedly connected to the shaft 302. The rope 208 is wound up by controlling the rotation of the shaft 302. Unwinding: A small gear 303 is fixedly connected to the shaft 302. A large gear 304 meshes with one side of the small gear 303. A central shaft 305 is fixedly connected to the large gear 304. The central shaft 305 is rotatably mounted on the bracket 301. A sector wheel 306 is fixedly connected to the central shaft 305. A friction pad 307 is provided on the side of the sector wheel 306 that contacts the surface of the piston rod 103. The elastic deformation of the friction pad 307 can be automatically compensated, thereby ensuring that the sector wheel 306 and the piston rod 103 are in continuous contact.

[0027] When the piston rod 103 moves outward, its surface generates tangential friction with the friction pad 307, thereby driving the sector wheel 306 to rotate around the central shaft 305. The sector wheel 306 drives the central shaft 305 and the large gear 304 to rotate synchronously, causing the small gear 303 to drive the shaft rod 302 to rotate, thereby unwinding the rope 208. Under its own elasticity, the concave section 2041 moves towards the piston rod 103 and gradually approaches and adheres to the surface of the piston rod 103, forming an M-shaped double-layer seal together with the protruding section 2042 and the sealing ring 205.

[0028] Reference Figure 8A torsion spring 308 is provided on the shaft 302. The two ends of the torsion spring 308 are fixedly connected to the bracket 301 and the pinion 303 respectively. When the piston rod 103 retracts inward, the torsion spring 308 releases elastic potential energy, which facilitates the shaft 302 to wind up the rope 208 and helps the concave section 2041 to reset.

[0029] Furthermore, refer to Figure 5 , Figures 10-13 A cleaning mechanism 400 is provided on the sealing seat 201. The cleaning mechanism 400 includes a fixing ring 401 fixedly connected to the sealing seat 201 and multiple sets of spring plates 402 equidistantly arranged along the circumference of the fixing ring 401. A brush 403 is provided on the inner side of the end of the spring plate 402 away from the sealing seat 201. The brush 403 is used to clean the surface of the piston rod 103. By removing the impurities attached to the surface of the piston rod 103, the impurity particles are prevented from entering the cylinder body 101, which would lead to sealing failure and increased wear.

[0030] Specifically, the cleaning mechanism 400 also includes a collar 404 that is slidably sleeved on the outer surface of the fixed ring 401. Multiple sets of rack plates 407 are fixedly connected to the collar 404 along the circumferential direction. The number of rack plates 407 is the same as the number of large gears 304, and they correspond one-to-one. The rack plates 407 extend into the second annular groove 203 and mesh with the corresponding large gears 304. The inner side of the collar 404 consists of a horizontal section 405 and an inclined section 406 from left to right. When the piston rod 103 moves outward, the large gear 304 rotates, causing the collar 404 to slide axially through the rack plates 407. At this time, the collar 404 slides to its initial position, i.e., the horizontal section 405 is in contact with the outer surface of the fixed ring 401. The inclined section 406 is in contact with the outer surface of the spring plate 402. The spring plate 402 is in an inclined state under its own elastic force. The brush 403 is away from the surface of the piston rod 103. When the piston rod 103 moves inward, the large gear 304 drives the collar 404 to slide axially through the rack plate 407. At this time, the horizontal section 405 slides to the outer surface of the spring plate 402 and squeezes the spring plate 402, making the spring plate 402 horizontal. The brush 403 is in close contact with the surface of the piston rod 103. At this time, during the process of the piston rod 103 moving inward, the brush 403 can continuously scrape off the impurities on the surface of the piston rod 103, preventing the impurities from entering the cylinder 101 with the piston rod 103.

[0031] The retaining ring 401 is sleeved on the surface of the piston rod 103, and there is a gap between the inner side of the retaining ring 401 and the surface of the piston rod 103 to facilitate the back-and-forth movement of the piston rod 103.

[0032] This invention provides a working principle for a hydraulic cylinder that is easy to maintain: When the hydraulic assembly 100 is working, the piston block 102 is driven by hydraulic oil within the cylinder body 101, causing the piston rod 103 to reciprocate. When the piston rod 103 is stationary in a non-working state, the sealing ring 205 in the sealing mechanism 200 is tightly fitted with the piston rod 103, forming a static seal to prevent hydraulic oil leakage. When the piston rod 103 extends outward, the surface of the piston rod 103 generates tangential friction with the friction pad 307 on the sector wheel 306, pushing the sector wheel 306 to rotate around the central axis 305. This rotation is then transmitted through the large gear 304 and the small gear. 303 meshing transmission drives the shaft 302 to rotate and unwind the rope 208. After the rope 208 is unwound, the concave section 2041 of the sealing kit 204 moves closer to the piston rod 103 under its own elasticity, forming an M-shaped double-layer sealing structure with the protruding section 2042 and the sealing ring 205, enhancing the sealing effect. At the same time, the rotation of the large gear 304 drives the collar 404 of the cleaning mechanism 400 to slide axially through the rack plate 407, so that the inclined section 406 is in contact with the spring plate 402. The spring plate 402 tilts outward under its own elasticity, and the brush 403 moves away from the piston rod 103 to prevent interference with the sealing action.

[0033] When the piston rod 103 retracts inward, it pushes the sector wheel 306 to rotate in reverse around the central axis 305. Through the meshing of the large gear 304 and the small gear 303, the drive shaft 302 rotates in reverse to wind up the rope 208. At the same time, the torsion spring 308 releases its elastic potential energy, driving the drive shaft 302 to stably wind up the rope 208. At this time, the concave section 2041 resets and restores the initial sealing state. Meanwhile, the large gear 304 drives the collar 404 to slide again, and the horizontal section 405 slides to the spring plate 402, squeezing the spring plate 402 to make it horizontal. The brush 403 is in close contact with the surface of the piston rod 103, continuously scraping away impurities as the piston rod 103 moves inward, preventing impurities from entering the cylinder 101.

[0034] The present invention also provides a hydraulic gate opener using the hydraulic cylinder, wherein the hydraulic cylinder includes a frame 500, a cylinder body 101 is hinged to the frame 500, and a gate 600 is hinged to the end of the piston rod 103. The gate 600 is used to open and close the channel provided on the frame 500.

[0035] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A hydraulic cylinder that is easy to maintain, comprising: A hydraulic assembly (100), comprising a cylinder (101), a piston block (102) disposed within the cylinder (101), a piston rod (103) fixedly connected to the piston block (102), and an oil injection hole (104) disposed on the cylinder (101), characterized in that it further comprises: A sealing mechanism (200) is provided on the cylinder body (101). The sealing mechanism (200) includes a sealing seat (201) fixedly installed on the right end of the cylinder body (101). The sealing seat (201) is sleeved on the surface of the piston rod (103). The sealing seat (201) is provided with a first annular groove (202) and a second annular groove (203) from left to right. A sealing kit (204) is provided in the first annular groove (202). The sealing kit (204) includes a concave section (2041) and a convex section (2042). The convex section (2042) is symmetrically arranged on both sides of the concave section (2041). A sealing ring (205) is fixedly connected to the side of the convex section (2042) away from the concave section (2041). The sealing ring (205) is fixed in the first annular groove (202), and the inner side of the sealing ring (205) is in contact with the surface of the piston rod (103). The outer surface of the concave section (2041) is equidistantly distributed with multiple sets of abutting blocks (206) along the circumferential direction. A connecting rod (207) is fixedly connected to the abutting block (206), and a rope (208) is fixedly connected to the connecting rod (207). The concave section (2041) is controlled to move closer to or away from the piston rod (103) by the rope (208).

2. The easy-to-maintain hydraulic cylinder according to claim 1, characterized in that, The second annular groove (203) is provided with triggering mechanisms (300) that correspond one-to-one with the rope (208) along the circumferential direction. The triggering mechanism (300) includes a bracket (301) fixedly connected in the second annular groove (203) and a shaft (302) rotatably mounted on the bracket (301). The other end of the rope (208) extends into the second annular groove (203) and is wound around the shaft (302). The rope (208) is wound up and unwound by controlling the rotation of the shaft (302).

3. The easy-to-maintain hydraulic cylinder according to claim 2, characterized in that, A small gear (303) is fixedly connected to the shaft (302). A large gear (304) meshes with one side of the small gear (303). A central shaft (305) is fixedly connected to the large gear (304). The central shaft (305) is rotatably mounted on the bracket (301). A sector wheel (306) is fixedly connected to the central shaft (305). A friction pad (307) is provided on the side of the sector wheel (306) that contacts the surface of the piston rod (103). The piston rod (103) moves outward to control the sector wheel (306) to flip, causing the shaft (302) to unwind the rope (208) and release the deformation constraint on the concave section (2041).

4. The easy-to-maintain hydraulic cylinder according to claim 3, characterized in that, The sealing seat (201) is provided with a cleaning mechanism (400). The cleaning mechanism (400) includes a fixing ring (401) fixedly connected to the sealing seat (201) and multiple sets of spring plates (402) equidistantly arranged along the circumferential direction of the fixing ring (401). A brush (403) is provided on the inner side of the end of the spring plate (402) away from the sealing seat (201).

5. The easy-to-maintain hydraulic cylinder according to claim 4, characterized in that, The cleaning mechanism (400) further includes a collar (404) that is slidably sleeved on the outer surface of the fixed ring (401). Multiple sets of rack plates (407) are fixedly connected to the collar (404) along the circumferential direction. The rack plates (407) extend into the second annular groove (203) and mesh with the corresponding large gear (304).

6. The easy-to-maintain hydraulic cylinder according to claim 5, characterized in that, The inner side of the collar (404) consists of a horizontal section (405) and an inclined section (406) from left to right. When the inclined section (406) is in contact with the outer surface of the spring plate (402), the spring plate (402) is in an inclined state and the brush (403) is away from the surface of the piston rod (103). When the horizontal section (405) is in contact with the outer surface of the spring plate (402), the spring plate (402) is in a horizontal state and the brush (403) is in contact with the surface of the piston rod (103).

7. The easy-to-maintain hydraulic cylinder according to claim 2, characterized in that, A torsion spring (308) is provided on the shaft (302), and the two ends of the torsion spring (308) are fixedly connected to the bracket (301) and the pinion (303) respectively.

8. The easy-to-maintain hydraulic cylinder according to claim 2, characterized in that, The second annular groove (203) is provided with guide wheels (209) that correspond one-to-one with the rope (208) at equal intervals along the circumferential direction, and the rope (208) and the guide wheels (209) slide in contact.

9. The easy-to-maintain hydraulic cylinder according to claim 4, characterized in that, The fixing ring (401) is sleeved on the surface of the piston rod (103), and there is a gap between the inner side of the fixing ring (401) and the surface of the piston rod (103).

10. A hydraulic gate opener using the hydraulic cylinder described in claim 5, characterized in that, Includes a frame (500), the cylinder (101) is hinged to the frame (500), and the end of the piston rod (103) is hinged to a gate (600), which is used to open and close the channel set on the frame (500).

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