Multi-ring combined oil-free sealing structure

Abstract

The invention discloses a multi-ring combined oil-free sealing structure. The multi-ring combined oil-free sealing structure is composed of a sealing ring groove, sealing ring lining rubber in the groove, a sealing ring and a sliding sealing face. A sealing ring rubber lining groove formed in the sealing ring groove is a narrow groove, a sealing ring groove is a wide groove, the narrow groove and the wide groove are overlapped to form a large groove-shaped structure and a small groove-shaped structure, sealing ring rubber lining is arranged in the narrow groove in the bottom of the sealing ring groove to provide elastic supporting, a sealing ring (made of abrasion-resistant materials) with staggered openings is arranged in the large groove, the openings of the sealing ring are of a stepped staggered opening structure, and ring openings are staggered. The other face of the sealing ring and the lining rubber ring of the narrow groove achieve sealing, and the lining rubber ring of the sealing ring provides an elastic effect to reinforce sealing of the whole radial face. The problems caused by lubricating oil are avoided, oil-free operation of equipment is achieved, the maintenance cost is reduced, and environmental pollution is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of dynamic sealing technology, and specifically relates to a multi-ring combined oil-free sealing structure, which is mainly suitable for reciprocating vacuum pumps, air compressors, hydraulic pumps, water pumps, oil cylinders, air cylinders and low-grade engines and other fields, and is especially suitable for piston-type reciprocating motion sealing of reciprocating vacuum pumps. It can also be used for sealing in scenarios such as rotary motion, rotational motion, and swinging motion between two components. Background Art

[0002] In existing reciprocating pump-related equipment, the performance of seals plays a crucial role in equipment operation. The applicant's two utility models, "A Low-Resistance Check Valve Reciprocating Pump" (Patent No. 2021219713237) and "A Series Two-Stage Reciprocating Pump" (Patent No. 2021219713364), involve novel reciprocating pumps. The original design of the piston ring (seal) used an apron structure, requiring lubrication during operation. This not only increased maintenance costs and work complexity, but also presented the risk of lubricant leakage and contamination of the working environment. To achieve oil-free operation, materials such as polytetrafluoroethylene were used for the piston ring.

[0003] However, although polytetrafluoroethylene material has many advantages, it also has obvious defects. It has a large thermal expansion coefficient, large plastic deformation and poor elasticity. When used as a piston ring, overheating of the equipment will cause excessive piston resistance and plastic deformation. After the equipment cools down, the piston ring will shrink excessively, forming a gap between the piston ring and the cylinder, seriously affecting the working performance of the equipment. Existing piston rings such as the WLW reciprocating vacuum pump use a stepped opening method to try to compensate for the thermal expansion and contraction effect, but the ring opening gap will increase the leakage. Moreover, after long-term use and wear, the roundness of the piston ring and the cylinder changes, and gaps appear on the fitting surface, further increasing the leakage. At the same time, the thickness of the piston ring becomes thinner, and the gap at the bottom of the groove increases, causing a large amount of airflow to leak from the bottom end, greatly shortening the service life of the entire machine. Therefore, a new sealing structure is urgently needed to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-ring combined oil-free sealing structure, which reduces leakage, improves sealing performance, extends product service life, realizes oil-free operation of equipment, and solves the problems existing in the above-mentioned prior art through innovative sealing structure design.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a multi-ring combined oil-free sealing structure, comprising a sealing ring groove, a sealing ring lining rubber in the groove, a sealing ring and a sliding sealing surface; the sealing ring lining rubber groove provided in the sealing ring groove is a narrow groove, and the sealing ring groove is a wide groove, which are superimposed to form a large and a small groove-shaped structure, the narrow groove at the bottom of which is filled with a sealing ring lining rubber to provide elastic support, the large groove is filled with a sealing ring with staggered openings (made of wear-resistant material), the openings of the sealing ring adopt a stepped staggered structure, the ring openings are staggered with each other, forming a sliding seal with the sliding sealing surface, the other side of the sealing ring is sealed with the inner lining rubber ring of the narrow groove, and the sealing ring lining rubber provides elasticity to strengthen the sealing of the entire radial surface.

[0006] Furthermore, the oil-free sealing structure is applied to a piston-type outer diameter seal, which includes a piston assembly, which is composed of a piston outer ring, a piston inlet plate and a piston outlet plate; In piston applications, the sealing ring is a piston ring, and the sliding sealing surface is the inner wall of the cylinder. The sealing ring groove is located on the outer diameter surface of the piston, and the internal narrow groove is equipped with a piston sealing ring lining rubber. The piston sealing ring lining rubber is in elastic contact with the inner diameter surface of the piston ring installed in the wide groove, and the outer diameter surface of the piston ring is slidably matched with the inner diameter surface of the cylinder; the piston ring, piston ring lining rubber and the outer ring of the piston are installed in the groove formed between the piston inlet plate and the piston outlet plate to form a labyrinth seal combination, and the piston assembly is slidably matched with the inner diameter of the cylinder liner through the piston ring.

[0007] Furthermore, the oil-free sealing structure is applied to a baffle-type inner diameter seal, which includes a baffle assembly consisting of an inner baffle, an outflow baffle, and an inflow baffle; In the partition application, the sealing ring is a partition sealing ring, and the sliding sealing surface is the outer diameter surface of the piston shaft rod. The sealing ring groove is located on the inner diameter surface of the inner partition plate, and the narrow groove at the bottom is equipped with a partition sealing ring lining rubber. The partition sealing ring lining rubber is in elastic contact with the outer diameter surface of the partition sealing ring installed in the wide groove, and the inner diameter surface of the partition sealing ring is slidably matched with the outer diameter surface of the piston shaft rod; the partition sealing ring openings are installed in a staggered manner; the other end of the inner partition plate is installed in the groove-shaped space composed of the outflow partition plate and the inlet partition plate to form a labyrinth seal shaft sealing combination, which is slidably matched with the outer diameter surface of the piston shaft rod for sealing.

[0008] Furthermore, the oil-free sealing structure is applied to a plunger-type outer diameter seal; In the plunger application, a plunger is installed inside the hydraulic cylinder; the sealing ring is the plunger ring, and the sliding sealing surface is the inner wall of the hydraulic cylinder. The sealing ring groove is located on the outer diameter surface of the plunger, and the inner narrow groove is equipped with a plunger ring lining rubber. The plunger ring lining rubber is in elastic contact with the inner diameter surface of the plunger ring installed in the wide groove, and the outer diameter surface of the plunger ring is slidably matched with the inner diameter surface of the hydraulic cylinder; a plunger guide belt is also installed on the inner diameter surface of the hydraulic cylinder, and the plunger can make free reciprocating motion inside the hydraulic cylinder. Furthermore, the sealing ring adopts a multi-step ring combination staggered form, is staggeredly installed through multiple open rings, and is lined with multiple sealing ring linings for sealing.

[0009] Furthermore, the sealing ring is a piston ring. When the number of the sealing ring is greater than one, an open positioning block is provided on each piston ring. The open positioning block is a convex structure, one end of which is embedded in an interlaced opening on the piston ring, and the other end is provided in a piston ring positioning groove opened on the outer ring of the piston.

[0010] Furthermore, in the multi-step ring, the staggered openings on the same sealing ring are composed of more than two steps.

[0011] Furthermore, the sealing ring adopts the form of a combination of a wide ring and a narrow ring.

[0012] Furthermore, the sealing ring lining rubber is hollow or solid.

[0013] Furthermore, the sealing ring material is rubber, nylon, bakelite, polytetrafluoroethylene or polyimide.

[0014] The present invention adopts a multi-step ring staggered structure, with multiple open rings installed in a staggered manner and lined with multiple rubber rings to form a labyrinthine sealing structure. A double-ring staggered structure is adopted, with two open rings installed in the same groove in a staggered manner, lined with a single rubber ring for sealing, and an additional piston ring opening positioning block is provided to prevent the piston ring from misaligning during operation. In the multi-step ring structure, the same ring is composed of two or more steps to enhance the sealing effect; the sealing ring combination includes the use of wide rings and narrow rings; the lining rubber ring can be hollow or solid, depending on actual needs.

[0015] When specifically applied to a reciprocating vacuum pump, the piston assembly's outer ring outer diameter surface is provided with a piston ring groove, in which a piston ring is installed. A piston ring liner is installed on the inner diameter surface of the piston ring. The piston ring has staggered openings, forming a labyrinth seal assembly with the piston ring liner. The piston assembly slides with the cylinder liner inner diameter through the piston ring. The inner diameter surface of the inner diaphragm of the diaphragm assembly is provided with a shaft seal ring groove, in which a diaphragm seal ring is installed. The diaphragm seal ring openings are staggered, and the diaphragm seal ring liner is installed on the outer diameter surface, forming a shaft seal assembly that slides with the outer diameter surface of the piston shaft to seal.

[0016] The present invention utilizes a multi-ring staggered opening design, where each sealing ring blocks leaks from the other's gaps. The inner rubber ring further blocks the connections between the openings, forming a multi-stage seal that significantly improves overall sealing performance. Compared to traditional open piston rings, equipment using these sealing rings achieves a higher vacuum level and greater pressure retention after shutdown. When the sealing rings or cylinder become worn, the inner rubber ring, due to its elasticity, can effectively fill the gaps caused by wear, maintaining a good sealing effect and thus extending the product's service life. Prototypes using the technology of the present invention have been operating stably for over a year with no significant performance degradation and improved pressure retention. The present invention changes the working method of traditional rubber ring seals that require the addition of lubricating oil, avoiding a series of problems caused by lubricating oil, achieving oil-free operation of the equipment, reducing maintenance costs, and minimizing environmental pollution. A variety of seal installation methods, ring combinations, and rubber ring types can be flexibly selected and adjusted according to the working requirements and working conditions of different equipment, thus providing wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of an example of a combination of the present invention for a cylinder; Figure 2 is a cross-sectional schematic diagram of a piston assembly and a partition assembly; Figure 3 Schematic diagram of the plunger assembly structure; Figure 4 It is a schematic diagram of a double piston ring combination; Figure 5 This is a schematic diagram of the combination of double piston rings and piston ring lining rubber; Figure 6 This is a schematic diagram of the combination of double piston rings and open positioning blocks; Figure 7 This is a diagram showing the connection between the open positioning block, the piston ring and the piston outer ring; Figure 8 Schematic diagram of the stepped entrance for various schemes; Figure 9 Schematic diagram of various piston ring liner rubber solutions; Figure 10 Schematic diagram of hollow rubber lining with various schemes; Figure 11 This is a diagram showing the degree of wear of the cylinder measured using a cylinder gauge; Figure 12 This is a picture showing the degree of wear inside the cylinder; Figure 13 This is a diagram showing the wear of the piston ring measured using a vernier caliper; Figure: 1. Piston assembly; 2. Spacer assembly; 3. End cap; 4. Cylinder liner; 5. Piston shaft; 6. Inlet port; 7. Exhaust port; 8. Flange; 9. Plunger; 10. Shaft extension sleeve; 11. Piston outer ring; 12. Piston inlet plate; 13. Piston outlet plate; 14. Piston flow hole; 15. Piston guide strip; 16. Piston ring; 17. Piston ring rubber lining; 18. Piston side rubber buffer; 19. Plunger ring; 20. Plunger ring rubber lining; 21. Inner spacer; 22. Inlet spacer; 23. Outlet spacer; 24. Spacer flow hole; 25. Plunger guide strip; 26. Spacer seal ring; 27. Spacer seal ring rubber lining; 28. Spacer rubber buffer; 29. ​​Hydraulic cylinder; 30. Piston ring positioning groove; 31. Opening positioning block; 32. Piston ring stepped opening. DETAILED DESCRIPTION

[0018] The embodiments of the present invention will now be described with reference to the accompanying drawings. It will be understood by those skilled in the art that the following embodiments are intended to illustrate the present invention only and should not be construed as limiting the scope of the present invention. Where specific techniques, connections, or conditions are not specified in the examples, the techniques, connections, and conditions described in the literature in the art or in accordance with the product specifications were used. Materials, instruments, or equipment used, where the manufacturer is not specified, are all commercially available conventional products.

[0019] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "provided with" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0020] A multi-ring oil-free seal structure consists of a sealing ring groove, a sealing ring lining within the groove, a sealing ring, and a sliding sealing surface. The sealing ring lining groove within the sealing ring groove is a narrow groove, and the sealing ring groove is a wide groove, forming a large and a small groove structure. The bottom narrow groove is filled with a sealing ring lining to provide elastic support. The large groove is filled with a sealing ring with staggered openings (made of wear-resistant material). The sealing ring openings adopt a stepped staggered structure, with the ring openings staggered to form a sliding seal with the sliding sealing surface. The other side of the sealing ring seals with the inner rubber ring of the narrow groove. The sealing ring lining provides elasticity to strengthen the seal along the entire radial surface. The sealing ring is made of rubber, nylon, bakelite, polytetrafluoroethylene, or polyimide. Example 1

[0021] like Figure 1 and Figure 2As shown, the oil-free sealing structure is applied to the piston and cylinder sealing of a reciprocating vacuum pump; it includes a piston assembly 1, which is composed of a piston outer ring 11, a piston inlet plate 12 and a piston outlet plate 13; Among them, the sealing ring is a piston ring 16, the sliding sealing surface is the inner wall of the cylinder, a piston ring groove is provided on the outer diameter surface of the piston outer ring 11, the piston ring 16 is installed in the groove, and a piston ring lining rubber 17 is installed on the inner diameter surface of the piston ring 16; the piston ring 16 has staggered openings, and the piston ring lining rubber 17 plays a compensating sealing role for the staggered ring openings and has a supporting role for the piston ring 16, so that the piston ring 16 can fit closely to the inner diameter of the cylinder liner 4 to avoid gaps. The piston outer ring 11 with the piston ring 16 and piston ring lining rubber 17 installed is installed in the groove formed between the piston inlet plate 12 and the piston outlet plate 13 to form a labyrinth seal assembly; the piston assembly 1 is slidably matched with the inner diameter of the cylinder liner 4 through the piston ring 16; during operation, when there is a pressure difference on both sides of the piston, the multi-step piston ring acts as a labyrinth seal to prevent the fluid from moving from the high-pressure direction to the low-pressure direction.

[0022] When the equipment is new, the clearances between the various parts are small, resulting in minimal leakage. However, as the piston ring 16 and cylinder wear during use, the gap between the piston ring 16 and the ring groove increases. At this point, the piston ring liner 17, with its elasticity (e.g., using an elastic rubber ring such as an O-ring), fills the gap created by wear, effectively enhancing the sealing effect and extending the service life of the entire machine. Example 2

[0023] like Figure 1 As shown, in this embodiment, a baffle assembly 2 is installed at both ends of the cylinder liner 4. The two sets of baffle assemblies differ slightly in shape and structure (representing different implementations). The baffle assembly 2 consists of an inner baffle 21, an outflow baffle 22, and an inflow baffle 23. The inner diameter surface of the inner baffle 21 is provided with a shaft seal ring groove, within which a baffle seal ring 26 is installed. The baffle seal rings 26 are installed with staggered openings. A baffle seal ring liner 27 is also installed on its outer diameter surface. This baffle seal is installed within the groove-shaped space formed by the baffle seal plate and the outflow baffle, forming a labyrinth seal shaft seal assembly. This assembly slides and seals against the outer diameter surface of the piston shaft 5 and fits entirely into the groove formed between the inflow baffle 23 and the outflow baffle 22. The inflow baffle 23 and the outflow baffle 22 can be secured by pressing the two piston shafts together, or by threading the two pieces together, or by using piston plate set screws to effectively seal the piston shaft and prevent fluid leakage. Example 3

[0024] like Figure 3As shown, in the plunger application, the plunger is installed inside the hydraulic cylinder, and the plunger ring and plunger ring lining rubber are applied to the plunger ring groove opened by the plunger to play a sealing role.

[0025] The sealing ring is a plunger ring 19, and the sliding sealing surface is the inner wall of the hydraulic cylinder 29. The sealing ring groove is located on the outer diameter surface of the plunger 9, and the internal narrow groove is equipped with a plunger ring lining rubber 20. The plunger ring lining rubber is in elastic contact with the inner diameter surface of the plunger ring 19 installed in the wide groove. The outer diameter surface of the plunger ring 19 is slidably matched with the inner diameter surface of the hydraulic cylinder 29; a plunger guide belt 25 is also installed on the inner diameter surface of the hydraulic cylinder, and the plunger can make free reciprocating motion inside the hydraulic cylinder. Example 4

[0026] like Figure 4 and Figure 5 As shown, the opening of the sealing ring has a variety of staggered openings: the sealing ring can have a single stepped opening or multiple stepped openings; the sealing ring can be composed of a convex opening and a concave opening staggered together, and the convex opening can adopt a single stepped opening or multiple stepped openings; the sealing ring can not only work as a single ring, but also be composed of multiple rings, the width of the rings can be the same, or rings of different widths can be used (wide rings and narrow rings are matched), and a variety of staggered steps can be used.

[0027] Since the diaphragm sealing ring, piston ring and plunger ring only differ in size, the piston ring 16 is taken as an example. Figure 4 As shown, the sealing ring is composed of two piston rings 16, both piston rings 16 are provided with piston ring stepped openings 32, and the piston ring stepped openings 32 on the two piston rings are symmetrically arranged; Figure 5 As shown, the inner walls of the two piston rings 16 are provided with piston ring lining rubber 17 .

[0028] like Figure 8 As shown, in addition to the structure of Example 1, each independent piston ring can have its own stepped, staggered opening. Alternatively, multiple piston rings with stepped openings can be installed in a stacked configuration. During use, a single independent piston ring can easily experience slight deformation at its opening, leading to increased leakage. However, staggering the two rings (preferably with a 180-degree staggered angle between the openings during installation, though other angles are also acceptable) can reduce leakage. Furthermore, the number of piston rings 16 stacked is not limited to two; three, four, or even more can be installed, further enhancing sealing performance. Example 5

[0029] like Figure 6 and Figure 7As shown, there are two piston rings 16. To prevent the piston rings 16 from misaligning after prolonged operation, each piston ring 16 is equipped with an open positioning block 31. This block 31 is a convex-shaped structure, with one end inserted into a piston ring step 32 on the piston ring 16 and the other end positioned within a piston ring positioning groove 30 provided on the piston outer ring 11. Specifically, the raised portion of the block 31 corresponds to the opening of one of the piston ring steps. The number of blocks is determined by the number of piston rings. For example, two piston rings use two positioning blocks, preferably with an angle of 180 degrees; three piston rings use three positioning blocks, preferably with angles staggered by 120 degrees (and similarly for more rings; these angles are only preferred and other angles are not excluded). This effectively stabilizes the angles of the piston rings, ensuring the stability of their sealing effect. Example 6

[0030] Taking the piston ring as an example, the staggered opening (piston ring stepped opening 32) on the piston ring 16 is composed of a convex opening and a concave opening staggered together; the convex opening adopts a single stepped opening or a multi-step stepped opening or a combination of the two, such as Figure 8 As shown; the number of piston rings 16 is at least one, and the number of piston ring lining rubber 17 is also at least one; when the number of piston rings 16 is greater than one, multiple piston rings are stacked and placed in the piston ring groove (sealing ring groove), or a piston ring groove for placing piston rings is added to the outer diameter surface of the piston outer ring 11; the widths of multiple piston rings 16 can be the same, or rings of different widths can be used (wide rings and narrow rings are matched), and a variety of stepped staggered forms can be used; the piston ring lining rubber 17 can be set to one, two or more according to the number of piston ring openings, and its cross-sectional shape can be circular or other shapes, or hollow or solid. Multiple lining rings can be installed in one groove at the same time, or separately in multiple grooves to meet different sealing requirements and equipment working conditions, such as Figure 9 and Figure 10 shown.

[0031] Take piston ring lining rubber as an example, Figure 9 and Figure 10 As shown, the cross-sectional shape of the piston ring liner in the cylinder piston structure can be circular or other shapes, and can also be hollow or solid. Multiple piston ring liners can be installed simultaneously in one groove or separately in multiple grooves to meet different sealing requirements and equipment operating conditions.

[0032] After the prototype machine using the technology of the present invention has been in operation for more than one year, no performance degradation caused by wear during use has been found. After disassembly and measurement, one cylinder at the exhaust port end of the fore-stage pump has been worn by 21 threads, and the wear of the other cylinders does not exceed 3 threads. The maximum wear of the piston ring does not exceed 2 threads, and the piston ring lining rubber compensates for more than 80 threads. In other words, as long as the wear does not exceed 80 threads, the stable operation of the whole machine can be guaranteed. In addition, when the wear is too large, the main replacement is only the cylinder and piston ring at the exhaust port end of the fore-stage pump. Since the price of small-displacement fore-stage pumps is not expensive, there is no need to repair it, and the fore-stage pump assembly can be directly replaced. Figure 11 This is a diagram showing the degree of wear of the cylinder measured using a cylinder gauge; Figure 12 This is a picture showing the degree of wear inside the cylinder; Figure 13 Diagram showing the wear degree of the piston ring measured with a vernier caliper.

[0033] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A multi-ring combined oil-free sealing structure, characterized in that: It consists of a sealing ring groove, a sealing ring lining rubber in the groove, a sealing ring and a sliding sealing surface; the sealing ring lining rubber groove arranged in the sealing ring groove is a narrow groove, and the sealing ring groove is a wide groove, which are superimposed into a large and a small groove structure, the narrow groove at the bottom is filled with a sealing ring lining rubber to provide elastic support, the large groove is filled with a sealing ring with staggered openings, the opening of the sealing ring adopts a stepped staggered structure, the ring openings are staggered with each other, forming a sliding seal with the sliding sealing surface, and the other side of the sealing ring is sealed with the inner lining rubber ring of the narrow groove.

2. The multi-ring combined oil-free sealing structure according to claim 1, characterized in that: The oil-free sealing structure is applied to piston-type outer diameter sealing, which includes a piston assembly, which is composed of a piston outer ring, a piston inlet plate and a piston outlet plate; In piston applications, the sealing ring is a piston ring, and the sliding sealing surface is the inner wall of the cylinder. The sealing ring groove is located on the outer diameter surface of the piston, and the internal narrow groove is equipped with a piston sealing ring lining rubber. The piston sealing ring lining rubber is in elastic contact with the inner diameter surface of the piston ring installed in the wide groove, and the outer diameter surface of the piston ring is slidably matched with the inner diameter surface of the cylinder; the piston ring, piston ring lining rubber and the outer ring of the piston are installed in the groove formed between the piston inlet plate and the piston outlet plate to form a labyrinth seal combination, and the piston assembly is slidably matched with the inner diameter of the cylinder liner through the piston ring.

3. The multi-ring combined oil-free sealing structure according to claim 1, characterized in that: The oil-free sealing structure is applied to a baffle-type inner diameter seal, which includes a baffle assembly consisting of an inner baffle, an outflow baffle, and an inflow baffle; In the partition application, the sealing ring is a partition sealing ring, and the sliding sealing surface is the outer diameter surface of the piston shaft rod. The sealing ring groove is located on the inner diameter surface of the inner partition plate, and the narrow groove at the bottom is equipped with a partition sealing ring lining rubber. The partition sealing ring lining rubber is in elastic contact with the outer diameter surface of the partition sealing ring installed in the wide groove, and the inner diameter surface of the partition sealing ring is slidably matched with the outer diameter surface of the piston shaft rod; the partition sealing ring openings are installed in a staggered manner; the other end of the inner partition plate is installed in the groove-shaped space composed of the outflow partition plate and the inlet partition plate to form a labyrinth seal shaft sealing combination, which is slidably matched with the outer diameter surface of the piston shaft rod for sealing.

4. The multi-ring combined oil-free sealing structure according to claim 1, characterized in that: The oil-free sealing structure is applied to plunger-type outer diameter seals; In the plunger application, a plunger is installed inside the hydraulic cylinder; the sealing ring is the plunger ring, and the sliding sealing surface is the inner wall of the hydraulic cylinder. The sealing ring groove is located on the outer diameter surface of the plunger, and the inner narrow groove is equipped with a plunger ring lining rubber. The plunger ring lining rubber is in elastic contact with the inner diameter surface of the plunger ring installed in the wide groove, and the outer diameter surface of the plunger ring is slidably matched with the inner diameter surface of the hydraulic cylinder; a plunger guide belt is also installed on the inner diameter surface of the hydraulic cylinder, and the plunger can make free reciprocating motion inside the hydraulic cylinder.

5. A multi-ring combined oil-free sealing structure according to any one of claims 1 to 4, characterized in that: The sealing ring adopts a multi-step ring combination staggered form, is installed through multiple open rings in a staggered manner, and is lined with multiple sealing ring linings for sealing.

6. The multi-ring combined oil-free sealing structure according to claim 5, characterized in that: The sealing ring is a piston ring. When the number of the sealing ring is greater than one, an open positioning block is provided on each piston ring. The open positioning block is a convex structure, one end of which is embedded in an interlaced opening on the piston ring, and the other end is set in the piston ring positioning groove opened on the outer ring of the piston.

7. A multi-ring combined oil-free sealing structure according to claim 5 or 6, characterized in that: In a multi-step ring, the staggered openings on the same sealing ring consist of two or more steps.

8. A multi-ring combined oil-free sealing structure according to claim 5 or 6, characterized in that: The sealing ring is in the form of a combination of a wide ring and a narrow ring.

9. A multi-ring combined oil-free sealing structure according to claim 1 or 5, characterized in that: The sealing ring lining rubber is hollow or solid.

10. A multi-ring combined oil-free sealing structure according to claim 1 or 5, characterized in that: The sealing ring material is rubber, nylon, bakelite, polytetrafluoroethylene or polyimide.

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