A piston seal arrangement for a hydraulic cylinder

Abstract

The utility model provides a kind of piston sealing structure for hydraulic cylinder, including cylinder barrel, the outer surface of cylinder barrel is fixedly connected with support rod, the bottom of cylinder barrel is fixedly connected with bottom plate, the bottom of bottom plate is fixedly connected with bushing, the top of cylinder barrel is fixedly connected with end cover, in piston rod moves, make sealing head move inside cylinder barrel, extrude the liquid of cylinder barrel, in the process of extrusion, push plate pushes liquid, the pressure generated presses plugging pad and spring, plugging pad deforms after being pressed, fill in the inner wall of cylinder barrel, form self-adapting sealing ring belt, effectively compensate the clearance change between sealing surface due to abrasion or machining deviation, support ring supports the inner ring of plugging pad to prevent the deformation of inner ring, so that plugging pad deformation can diffuse stably to the periphery, ensure that its deformation evenly spreads to the periphery, avoid local stress concentration or distortion failure, while maintaining the axial symmetry distribution of sealing pressure, reduce the risk of internal leakage, prolong the service life of sealing element, applicable to high frequency reciprocating, high pressure under sealing condition.

Description

Technical Field

[0001] This utility model relates to the field of fluid pressure actuator technology, specifically a piston sealing structure for a hydraulic cylinder. Background Technology

[0002] A hydraulic cylinder is a hydraulic actuator that converts hydraulic energy into mechanical energy and performs linear reciprocating motion. It has a simple structure and reliable operation. When used to achieve reciprocating motion, a speed reduction device can be eliminated, and there is no transmission backlash, resulting in smooth movement. Therefore, it is widely used in the hydraulic systems of various machines. To prevent oil leakage from the hydraulic cylinder to the outside or from the high-pressure chamber to the low-pressure chamber, sealing structures are set between the cylinder and the end cover, the piston and the piston rod, the piston and the cylinder, and the piston rod and the front end cover. However, the reciprocating motion of the piston seal is prone to wear of the seal, causing internal and external leakage, requiring frequent maintenance. The end cover seal is prone to failure under high pressure impact, resulting in oil leakage and environmental pollution.

[0003] Regarding the technical problems existing in the piston sealing structure for hydraulic cylinders mentioned above, a search revealed a patent (CN202321918544.7) for a piston sealing structure for hydraulic cylinders, relating to the field of mechanical equipment technology. The structure includes a cylinder, with a first sealing ring fixedly installed at one end, a first fixing bolt fixedly installed on one side of the first sealing ring, a piston rod disposed inside the cylinder, and a piston body fixedly installed at the other end of the piston rod. A first limiting groove is formed on the outer surface of the piston body. In this invention, by installing a first sealing ring at one end of the cylinder, providing a second sealing ring on the outer surface of the piston rod, and fixing an oil scraper ring at the other end of the second sealing ring, a second limiting groove is formed at the other end of the piston body, with the oil scraper ring matching the second limiting groove. The first and second sealing rings are made of nitrile rubber, which effectively reduces friction when the piston body moves, thus achieving a good sealing effect.

[0004] The sealing structure of this hydraulic cylinder is prone to performance degradation due to friction and wear during long-term reciprocating motion. The seals between the piston and cylinder barrel, and between the piston rod and guide sleeve, are continuously subjected to mechanical shear and compressive stress under high-speed or high-pressure conditions, gradually leading to material fatigue, hardening, or permanent deformation. After wear, the sealing gap increases, disrupting the original sealing force distribution and causing internal or external leakage. Internal leakage reduces efficiency and the accuracy of the actuator, while external leakage pollutes the environment and increases equipment downtime and maintenance costs. The static seal at the end cover is easily squeezed and fails under severe system pressure fluctuations or impact loads. The sealing ring or gasket at the connection surface between the end cover and the cylinder barrel undergoes elastic deformation under high pressure. If the preload is insufficient or the bolts are fatigued and loosened, high-pressure oil seeps out along this gap, causing corrosion or contaminating surrounding components. Utility Model Content

[0005] The purpose of this invention is to provide a piston sealing structure for hydraulic cylinders.

[0006] To achieve the above objectives, this utility model provides the following technical solution: It includes a cylinder, a support rod fixedly connected to the outer surface of the cylinder, a base plate fixedly connected to the bottom of the cylinder, a bushing fixedly connected to the bottom of the base plate, an end cap fixedly connected to the top of the cylinder, a dustproof tube fixedly connected to the bottom of the end cap, a sealing sheet fixedly connected to the bottom of the dustproof tube, a fixing ring fixedly connected to the top of the sealing sheet, an upper air cushion fixedly connected to the bottom of the sealing sheet, a compression air bladder fixedly connected to the bottom of the upper air bladder, a lower air cushion fixedly connected to the bottom of the compression air bladder, a compression sheet fixedly connected to the bottom of the lower air bladder, a piston rod movably connected inside the end cap, an ear ring fixedly connected to the top of the piston rod, a sealing head fixedly connected to the bottom of the piston rod, a spring fixedly connected to the middle of the bottom of the sealing head, a push plate fixedly connected to the bottom of the spring, a plugging gasket movably connected to the top of the push plate, a support ring fixedly connected inside the plugging gasket, and a support foot fixedly connected to the top of the support ring.

[0007] As a further embodiment of this utility model: a groove is provided at the bottom of the dustproof tube, and the sealing sheet is fixed in the groove of the dustproof tube by a fixing ring.

[0008] As a further embodiment of this utility model: the top edge of the upper air cushion is located at the inner ring edge of the sealing sheet, the dustproof tube is located at the connection between the upper air cushion and the sealing sheet, and the upper air cushion is embedded in the lower part of the interior where the dustproof tube is installed.

[0009] As a further embodiment of this utility model: the compression airbag is provided with a multi-layer folded structure, the cross-section of the upper air cushion and the lower air cushion is provided with a "V" shaped structure, and the compression piece is provided to abut against the top of the lower air cushion.

[0010] As a further embodiment of this utility model: the piston rod is moved from top to bottom inside the dustproof tube, the sealing head and the plug abut against the inner wall of the cylinder, the plug is a semi-circular arc structure, and the support ring is located at the highest point of the plug structure.

[0011] As a further embodiment of this utility model: the support foot is located around the support ring, and the plug is embedded inside the support ring and fixed to the sealing head.

[0012] Beneficial effects

[0013] 1. This utility model provides a piston sealing structure for hydraulic cylinders. When the piston rod moves, the sealing head moves inside the cylinder, squeezing the liquid in the cylinder. During the squeezing process, the push plate pushes the liquid, and the resulting pressure applies pressure to the gasket and spring. The gasket deforms under pressure and fills the inner wall of the cylinder, forming an adaptive sealing ring. This effectively compensates for changes in the sealing surface gap caused by wear or machining deviations. The support ring supports the inner ring of the gasket to prevent deformation of the inner ring, allowing the deformation of the gasket to spread stably in all directions. This ensures that the deformation spreads evenly in all directions, avoiding local stress concentration or torsional failure. At the same time, it maintains the axially symmetrical distribution of sealing pressure, reduces the risk of internal leakage, and extends the life of the seal. It is suitable for sealing situations under high frequency reciprocating and high pressure.

[0014] 2. This utility model provides a piston sealing structure for hydraulic cylinders. This end cap sealing structure effectively prevents external leakage through multiple compensation mechanisms. When the internal oil pressure increases, the hydraulic pressure pushes the extrusion plate to apply pressure to the sealing interface. The liquid impact causes the extrusion airbag to undergo adaptive deformation, forming a buffer effect and reducing the instantaneous impact on the end cap seal. The upper air cushion is affected by negative pressure and extends into the dustproof tube, forming an airtight buffer barrier, which not only compensates for the sealing gap but also prevents dust from entering. The sealing plate is kept stably positioned by the fixing ring, ensuring that the sealing surface is evenly fitted, significantly improving the adaptability of the end cap seal, extending the seal life and reducing maintenance costs, and fundamentally suppressing the leakage problem caused by pressure fluctuations. Attached Figure Description

[0015] Figure 1 This is a structural diagram of the hydraulic cylinder of this utility model.

[0016] Figure 2 This is a diagram of the piston sealing structure of this utility model.

[0017] Figure 3 This is a disassembled structural diagram of the piston rod of this utility model.

[0018] Figure 4 This is a disassembled structural diagram of the sealing head of this utility model.

[0019] Figure 5 This is a structural diagram of the dustproof pipe of this utility model.

[0020] Figure 6 This is a disassembled structural diagram of the dustproof tube of this utility model.

[0021] Figure 1-6In the middle: 1. Cylinder; 101. Support rod; 102. Base plate; 103. Bushing; 2. End cap; 201. Dustproof tube; 202. Sealing plate; 203. Retaining ring; 204. Upper air cushion; 205. Compression air bladder; 206. Lower air cushion; 207. Compression plate; 3. Piston rod; 301. Earring; 302. Sealing head; 303. Support ring; 304. Support foot; 305. Plug; 306. Spring; 307. Push plate. Detailed Implementation

[0022] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0023] Please see Figure 1-6 A piston sealing structure for a hydraulic cylinder includes a cylinder barrel 1, a support rod 101 fixedly connected to the outer surface of the cylinder barrel 1, a base plate 102 fixedly connected to the bottom of the cylinder barrel 1, a bushing 103 fixedly connected to the bottom of the base plate 102, an end cap 2 fixedly connected to the top of the cylinder barrel 1, a dustproof tube 201 fixedly connected to the bottom of the end cap 2, a sealing sheet 202 fixedly connected to the bottom of the dustproof tube 201, a fixing ring 203 fixedly connected to the top of the sealing sheet 202, an upper air cushion 204 fixedly connected to the bottom of the sealing sheet 202, a compression air bladder 205 fixedly connected to the bottom of the upper air cushion 204, a lower air cushion 206 fixedly connected to the bottom of the compression air bladder 205, and a compression plate 207 fixedly connected to the bottom of the lower air cushion 206.

[0024] In actual operation, the end cap sealing structure effectively prevents external leakage through multiple compensation mechanisms. When the internal oil pressure rises, the hydraulic pressure pushes the extrusion plate 207 to apply pressure to the sealing interface. The liquid impact causes the extrusion airbag 205 to undergo adaptive deformation, forming a buffer effect and reducing the instantaneous impact on the end cap seal. The upper air cushion 204 extends into the dustproof tube 201 under the influence of negative pressure, forming an airtight buffer barrier that both compensates for the sealing gap and prevents dust intrusion. The sealing plate 202 is kept stably positioned by the fixing ring 203, ensuring uniform contact of the sealing surface, significantly improving the adaptability of the end cap seal, extending the seal life and reducing maintenance costs, and fundamentally suppressing the leakage problem caused by pressure fluctuations.

[0025] In this embodiment, a groove is provided at the bottom of the dustproof tube 201, and the sealing sheet 202 is fixed in the groove of the dustproof tube 201 by the fixing ring 203. The top edge of the upper air cushion 204 is located at the inner ring edge of the sealing sheet 202. The dustproof tube 201 is located at the connection between the upper air cushion 204 and the sealing sheet 202. The upper air cushion 204 is embedded in the lower part of the dustproof tube 201. The compression airbag 205 is provided with a multi-layer folded structure. The cross-section of the upper air cushion 204 and the lower air cushion 206 is set with a "V" shaped structure. The compression sheet 207 is set to abut against the top of the lower air cushion 206.

[0026] Please see Figure 5-6 ,

[0027] A piston rod 3 is movably connected inside the end cap 2. An ear ring 301 is fixedly connected to the top of the piston rod 3. A sealing head 302 is fixedly connected to the bottom of the piston rod 3. A spring 306 is fixedly connected to the bottom middle of the sealing head 302. A push plate 307 is fixedly connected to the bottom of the spring 306. A plug 305 is movably connected to the top of the push plate 307. A support ring 303 is fixedly connected inside the plug 305. A support foot 304 is fixedly connected to the top of the support ring 303.

[0028] As the piston rod 3 moves, the sealing head 302 moves inside the cylinder 1, squeezing the liquid in the cylinder 1. During the squeezing process, the push plate 307 pushes the liquid, and the resulting pressure applies pressure to the plug 305 and the spring 306. The plug 305 deforms under pressure and fills the inner wall of the cylinder 1, forming an adaptive sealing ring. This effectively compensates for changes in the sealing surface gap caused by wear or machining deviations. The support ring 303 supports the inner ring of the plug 305 to prevent deformation of the inner ring, allowing the deformation of the plug 305 to spread stably in all directions. This ensures that the deformation spreads evenly in all directions, avoiding local stress concentration or torsional failure. At the same time, it maintains the axially symmetrical distribution of the sealing pressure, reduces the risk of internal leakage, and extends the life of the seal. It is suitable for sealing situations under high frequency reciprocating and high pressure.

[0029] In this embodiment, the piston rod 3 is moved from top to bottom inside the dustproof tube 201. The sealing head 302 and the plug 305 abut against the inner wall of the cylinder 1. The plug 305 is a semi-circular arc structure. The support ring 303 is located at the highest point of the plug 305 structure. The support foot 304 is located around the support ring 303. The plug 305 is embedded inside the support ring 303 and fixed to the sealing head 302.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and they should all be covered within the scope of the claims and specification of this utility model.

Claims

1. A piston sealing structure for a hydraulic cylinder, characterized in that, Including cylinder (1): A support rod (101) is fixedly connected to the outer surface of the cylinder (1). A base plate (102) is fixedly connected to the bottom of the cylinder (1). A bushing (103) is fixedly connected to the bottom of the base plate (102). An end cap (2) is fixedly connected to the top of the cylinder (1). A dustproof tube (201) is fixedly connected to the bottom of the end cap (2). A sealing sheet (202) is fixedly connected to the bottom of the dustproof tube (201). A fixing ring (203) is fixedly connected to the top of the sealing sheet (202). An upper air cushion (204) is fixedly connected to the bottom of the sealing sheet (202). A compression airbag (205) is fixedly connected to the bottom of the upper air cushion (204). The bottom of the compression airbag (205) is fixedly connected to the bottom of the compression airbag (205). A lower air cushion (206) is fixedly connected to the bottom of the lower air cushion (206), and a compression plate (207) is fixedly connected to the bottom of the lower air cushion (2). A piston rod (3) is movably connected inside the end cap (2). An ear ring (301) is fixedly connected to the top of the piston rod (3). A sealing head (302) is fixedly connected to the bottom of the piston rod (3). A spring (306) is fixedly connected to the middle of the bottom of the sealing head (302). A push plate (307) is fixedly connected to the bottom of the spring (306). A plug (305) is movably connected to the top of the push plate (307). A support ring (303) is fixedly connected inside the plug (305). A support foot (304) is fixedly connected to the top of the support ring (303).

2. The piston sealing structure for a hydraulic cylinder as described in claim 1, characterized in that: The bottom of the dustproof tube (201) is provided with a groove, and the sealing sheet (202) is fixed in the groove of the dustproof tube (201) by a fixing ring (203).

3. The piston sealing structure for a hydraulic cylinder as described in claim 1, characterized in that: The top edge of the upper air cushion (204) is located at the inner ring edge of the sealing sheet (202), and the dustproof tube (201) is located at the connection between the upper air cushion (204) and the sealing sheet (202). The upper air cushion (204) is embedded in the lower part of the interior where the dustproof tube (201) is located.

4. The piston sealing structure for a hydraulic cylinder as described in claim 1, characterized in that: The compression airbag (205) is provided with a multi-layer folded structure, the cross-section of the upper air cushion (204) and the lower air cushion (206) is provided with a "V" shaped structure, and the compression piece (207) is provided to abut against the top of the lower air cushion (206).

5. The piston sealing structure for a hydraulic cylinder as described in claim 1, characterized in that: The piston rod (3) is moved from top to bottom inside the dustproof tube (201). The sealing head (302) and the gasket (305) abut against the inner wall of the cylinder (1). The gasket (305) is a semi-circular arc structure. The support ring (303) is located at the highest point of the gasket (305).

6. The piston sealing structure for a hydraulic cylinder as described in claim 1, characterized in that: The support foot (304) is located around the support ring (303), and the plug (305) is embedded inside the support ring (303) and fixed to the sealing head (302).

Images