Piston sealing structure for hydraulic drive piston compressor

Abstract

The invention discloses a piston sealing structure for a hydraulic drive piston compressor, which comprises a piston, two sealing structures are arranged at the end part of the piston, and the two sealing structures are respectively a first sealing structure and a second sealing structure; wherein the sealing structure close to the end part of the piston is a first sealing structure; the second sealing structure is configured in the mode that under the condition that the first sealing structure plays a sealing role, the second sealing structure does not abrade with the inner wall face of the air cylinder along with periodic reciprocating motion of the piston. When the first sealing structure loses efficacy, the second sealing structure expands and deforms under air pressure to play a sealing role. According to the piston sealing structure of the hydraulically-driven piston compressor, the service life of the sealing structure of the hydraulically-driven piston compressor is prolonged through alternate work of the two sealing structures, and the safety and stability of system operation are improved.

Description

Technical Field

[0001] The invention relates to the technical field of compressors, and more particularly to a piston sealing structure for a liquid-driven piston compressor. Background Art

[0002] Among the three core equipment of hydrogen refueling stations - compressors, hydrogen storage containers and hydrogen refueling machines, compressors play an important role in pressurizing the hydrogen source of hydrogen refueling stations. The performance of the compressor directly determines the operating conditions of the hydrogen refueling station. The two most commonly used hydrogen compressors in hydrogen refueling stations are liquid-driven piston compressors and diaphragm compressors. Although both compressors are positive displacement reciprocating compressors, there are still great differences in their specific working principles, structures, etc., and their performance is also different. Therefore, how to combine the performance of the compressor and the specific conditions of the hydrogen refueling station to select and use the two compressors is of great significance for the construction and operation of hydrogen refueling stations. Liquid-driven piston compressors have attracted more and more attention due to their advantages such as load start and stop, high volumetric efficiency, few wearing parts, and simple maintenance. They are one of the main application forms of hydrogen compressors in hydrogen refueling stations in the future.

[0003] The hydraulic-driven piston compressor is a new type of compression that replaces the crank-connecting rod of the traditional reciprocating piston compressor with an electro-hydraulic drive. The hydraulic-driven piston compressor uses hydraulic oil to drive the oil piston to move, and the oil piston drives the gas piston to move through the piston rod to achieve the compression and exhaust of the working fluid. The combination of the combined cylinder block and the combined piston makes the seals of the hydrogen compressor of this structure dynamic seals. Therefore, the reliability and service life of the sealing structure seriously restrict the life and operation safety of the hydraulic-driven piston compressor.

[0004] The hydraulic-driven piston compressor is a new type of compression that uses an electro-hydraulic drive to replace the crank-connecting rod of the traditional reciprocating piston compressor. The hydraulic-driven piston compressor drives the oil piston to move, and the oil piston drives the gas piston to move through the piston rod to achieve the compression and exhaust of the working fluid. The combination of the combined cylinder and the combined piston makes the seals of the hydrogen compressor of this structure dynamic seals. Therefore, how to ensure the sealing performance of each part so that the hydraulic oil and hydrogen are isolated from each other and no leakage occurs is the key to this type of compressor.

[0005] The traditional piston ring sealing structure is applied to the liquid-driven piston compressor. Its safety cannot be effectively guaranteed under the working environment of high pressure difference. In addition, hydrogen leakage will greatly reduce the economy of the liquid-driven piston compressor.

[0006] At present, the liquid-driven piston compressors on the market mainly adopt the pan-seal sealing structure, but the pan-seal edge is relatively thin, and the wear will be aggravated if it is used for a long time without oil lubrication. If the pan-seal lip is thickened, the pan-seal material itself has limited yield strength in the interference fit with the cylinder of the liquid-driven piston compressor, which will make its structure more prone to failure. Therefore, the actual working life of the pan-seal in the existing technical solutions is less than 1,000 hours, which is a big gap from the expected life of 8,000 hours of the liquid-driven piston compressor in the hydrogenation station.

[0007] At present, there are also technical solutions that use axially distributed multi-channel pan-plug seals for sealing. However, since the hydraulic oil in the middle hydraulic chamber of the piston drives the combined piston to reciprocate left and right, the multiple pan-plug seals are in contact with the inner wall of the cylinder during the reciprocating motion of the piston and wear. Therefore, when the front pan-plug seal works normally, the rear pan-plug seal will also be worn. Therefore, the effect of improving the life of the piston seal of the liquid-driven piston compressor is limited, and the expected life span cannot be achieved. Summary of the invention

[0008] The object of the present invention is to provide a piston sealing structure for a liquid-driven piston compressor, in order to solve the technical problems in the background technology.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A piston sealing structure for a liquid-driven piston compressor comprises: a piston, wherein the end of the piston is provided with two sealing structures, namely a first sealing structure and a second sealing structure; wherein the sealing structure close to the end of the piston is the first sealing structure;

[0011] The second sealing structure is configured such that: when the first sealing structure is performing sealing work, the second sealing structure will not produce wear between the second sealing structure and the inner wall surface of the cylinder as the piston periodically reciprocates; when the first sealing structure fails, the second sealing structure expands and deforms under air pressure to perform a sealing function.

[0012] A more preferred technical solution is that a mounting groove is provided on the piston, and the first sealing structure and the second sealing structure are respectively and sequentially mounted in the mounting groove; and are limited by a retaining ring unit.

[0013] A more preferred technical solution is that the second sealing structure includes a sealing ring, a spring, and a retaining spring which are sequentially sleeved on the mounting groove, the sealing ring is sealed with the end face of the mounting groove, and the two ends of the spring are respectively abutted with the sealing ring and the retaining spring.

[0014] A more preferred technical solution is that the sealing ring includes a first gasket and a second gasket, the first gasket is a convex conical surface gasket, and the conical surface is arranged on the side facing the second gasket, the second gasket is a double-conical surface gasket matching with the first gasket, and the end face of the mounting groove is also arranged as a conical surface matching with the second gasket.

[0015] A more preferred technical solution is that annular notches are respectively provided on the inner ring and the outer ring of the second gasket, and the annular notches on both sides are arranged diagonally.

[0016] A more preferred technical solution is that the annular notch on the outer ring of the second gasket is arranged close to the first gasket.

[0017] A more preferred technical solution is that the first sealing structure includes: a pan-plug seal and a third gasket, the third gasket abuts against the retaining spring, and the pan-plug seal abuts against the third gasket; the pan-plug seal is limited by a retaining ring unit.

[0018] A more preferred technical solution is that the retaining ring unit includes a retaining ring and a supporting sleeve.

[0019] Compared with the prior art, the present invention has the following technical effects:

[0020] (1) The piston seal structure of the liquid-driven piston compressor designed by the present invention utilizes the successive operation of two sealing structures to increase the service life of the sealing structure of the liquid-driven piston compressor and improve the safety and stability of the system operation.

[0021] (2) The piston spring-double-cone seal structure of the liquid-driven piston compressor designed by the present invention has a gap between the inner wall surfaces of the cylinder when the pan-seal is working normally, which reduces the wear of the seal and increases the life of the piston of the liquid-driven piston compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A structural diagram of the piston seal of the liquid-driven piston compressor of the present invention;

[0023] Figure 2 A structural diagram of the second seal of the piston of the liquid-driven piston compressor of the present invention;

[0024] Figure 3 Structural diagram of the second seal (in operation) of the piston of the liquid-driven piston compressor of the present invention.

[0025] Illustration: 1- retaining ring, 2- supporting sleeve, 3- dirt retaining ring, 4- pan seal, 5- third gasket, 6- retaining ring, 7- spring, 8- conical gasket, 9- double conical gasket, 10- supporting ring, 11- piston, 12- cylinder. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below in conjunction with the drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals throughout represent the same or similar parts or parts with the same or similar functions. The described embodiments are part of the embodiments of the present application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0027] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0028] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, or it can be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0029] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are orientations or positional relationships based on the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0030] In addition, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or display that includes a series of steps or elements is not necessarily limited to those steps or elements explicitly listed but may include other steps or elements not explicitly listed or inherent to such process, method, product, or display.

[0031] The following will be combined Figure 1-Figure 3 , a piston sealing structure for a liquid-driven piston compressor involved in an embodiment of the present application is described in detail. It is worth noting that the following embodiments are only used to explain the present application and do not constitute a limitation on the present application.

[0032] Embodiment 1:

[0033] See also Figure 1, a piston sealing structure for a liquid-driven piston compressor, comprising: a piston 11, wherein the end of the piston is provided with two sealing structures, namely a first sealing structure and a second sealing structure; wherein the sealing structure close to the end of the piston is the first sealing structure;

[0034] The second sealing structure is configured such that: when the first sealing structure is performing sealing work, the second sealing structure will not produce wear between the second sealing structure and the inner wall surface of the cylinder as the piston periodically reciprocates; when the first sealing structure fails, the second sealing structure expands and deforms under air pressure to perform a sealing function.

[0035] In some embodiments, a mounting groove is provided on the piston, and the first sealing structure and the second sealing structure are respectively and sequentially installed in the mounting groove; and are limited by a retaining ring unit.

[0036] When the first Variseal seal is operating normally, the second sealing structure does not provide sealing effect to avoid simultaneous wear. When the first Variseal seal fails, the second sealing structure is compressed by gas pressure and compensates for the radial gap to achieve a sealing effect, thereby increasing the reliability and service life of the sealing structure, thereby improving the service life and reliability of the liquid-driven piston compressor.

[0037] In some embodiments, the second sealing structure includes a sealing ring, a spring, and a retaining spring which are sequentially sleeved on the mounting groove, the sealing ring is sealed with the end surface of the mounting groove, and the two ends of the spring are respectively abutted with the sealing ring and the retaining spring.

[0038] The sealing ring includes a first gasket and a second gasket. The first gasket is a convex conical gasket, and the conical surface is arranged on the side facing the second gasket. The second gasket is a double-conical gasket matched with the first gasket. The end surface of the mounting groove is also arranged as a conical surface matched with the second gasket. Annular notches are respectively provided on the inner ring and the outer ring of the second gasket, and the annular notches on both sides are arranged diagonally. The annular notch on the outer ring of the second gasket is arranged close to the first gasket.

[0039] The double-conical gasket 9 in the second sealing structure of the present invention is designed to have annular notches on both sides, such as Figure 2As shown, the conical surfaces on both sides cooperate with the pistons 11 and conical washers 8 on both sides, and the conical washers 8 are connected to the retaining spring 6 through the spring 7. Under the initial force of the spring 7, it can be ensured that the conical washers 8 and the double-conical washers 9 will not be displaced in the axial direction, and can always remain in the working position. When the first pan-seal seal structure works normally, the gas is sealed in front of the first seal structure, and the second seal structure is not affected by the gas pressure in the cylinder. In the present invention, under the initial spring force of the spring 7, the double-conical washers in the second seal structure are clearance-matched with the inner wall of the cylinder 12, and there is a small gap between the washers and the inner wall, so as to ensure that when the first seal structure works normally, the second seal structure will not be worn with the inner wall of the cylinder as the piston reciprocates periodically.

[0040] During the operation of the hydraulic-driven piston compressor, the hydraulic oil in the middle hydraulic chamber drives the combined piston to reciprocate left and right. Under high temperature and high pressure conditions, the first pan-seal structure is constantly worn during the friction between the first pan-seal structure and the inner wall of the cylinder. When the wear reaches a certain level, the first pan-seal structure fails. Figure 3 As shown, high-temperature and high-pressure gas leaks to the retaining spring 6 through the first sealing structure, and the gas pressure acts on the retaining spring 6 and the spring 7, thereby deforming the double-conical gasket 9 with notches on both sides. The radial dimension of the deformed double-conical gasket increases due to extrusion, and contacts with the inner wall surface of the cylinder 12 to produce an interference fit, thereby achieving a sealing effect.

[0041] The present invention designs two sealing structures, namely, a pan-seal and a spring-double-cone gasket seal, in the axial direction of the piston, and makes it possible for a gap to exist between the second sealing structure and the cylinder wall when the first sealing structure works normally, so that no sealing effect or wear can be produced. When the first sealing structure fails, gas leaks to the second sealing structure, and the second sealing structure achieves a sealing effect under the action of gas pressure. The two seals work alternately, which can effectively improve the service life of the piston sealing structure of the liquid-driven piston compressor. And if the piston length allows, multiple spring-double-cone sealing structures can be added to the rear side of the pan-seal sealing structure, so that multiple sealing structures can work at one time, greatly improving the sealing life of the liquid-driven piston compressor.

[0042] It should be noted that, in this embodiment, the first sealing structure includes: a pan-seal 4, a third gasket 5, the third gasket abuts against the retaining spring, and the pan-seal abuts against the third gasket; the pan-seal is limited by a retaining ring unit, the retaining ring unit includes a retaining ring 1 and a support sleeve 2, and a contamination ring 3 is provided on the support sleeve; the first sealing structure in the present invention mainly relies on the pan-seal to achieve the sealing effect. The pan-seal is a pan-seal ring, which is a high-performance seal with a special V-shaped spring installed in a U-shaped ring. The appropriate spring force plus the system gas pressure pushes the sealing lip surface out and gently presses the sealed metal surface to generate a very excellent sealing effect. The actuation effect of the spring can overcome the slight eccentricity of the metal mating surface and the wear of the sealing lip, and continue to maintain the expected sealing performance.

[0043] The above description is only a preferred embodiment of the present invention and is used to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A piston sealing structure for a liquid-driven piston compressor, characterized in that: include: A piston, wherein the end of the piston is provided with two sealing structures, namely a first sealing structure and a second sealing structure; wherein the sealing structure close to the end of the piston is the first sealing structure; The second sealing structure is configured such that: when the first sealing structure is performing sealing work, the second sealing structure will not produce wear between the second sealing structure and the inner wall surface of the cylinder as the piston periodically reciprocates; when the first sealing structure fails, the second sealing structure expands and deforms under air pressure to perform a sealing function.

2. A piston sealing structure for a liquid-driven piston compressor according to claim 1, characterized in that: The piston is provided with an installation groove, and the first sealing structure and the second sealing structure are respectively and sequentially installed in the installation groove, and are limited by a retaining ring unit.

3. A piston sealing structure for a liquid-driven piston compressor according to claim 2, characterized in that: The second sealing structure comprises a sealing ring, a spring and a retaining spring which are sequentially sleeved on the mounting groove. The sealing ring is sealed with the end surface of the mounting groove, and the two ends of the spring are respectively in contact with the sealing ring and the retaining spring.

4. A piston sealing structure for a liquid-driven piston compressor according to claim 3, characterized in that: The sealing ring includes a first gasket and a second gasket. The first gasket is a convex conical gasket, and the conical surface is arranged on the side facing the second gasket. The second gasket is a double-conical gasket matching with the first gasket. The end face of the mounting groove is also arranged as a conical surface matching with the second gasket.

5. The piston sealing structure for a liquid-driven piston compressor according to claim 3, characterized in that: Annular notches are respectively provided on the inner ring and the outer ring of the second gasket, and the annular notches on both sides are arranged diagonally.

6. A piston sealing structure for a liquid-driven piston compressor according to claim 5, characterized in that: The annular notch on the outer ring of the second gasket is arranged close to the first gasket.

7. A piston sealing structure for a liquid-driven piston compressor according to claim 6, characterized in that: The first sealing structure includes: a pan-plug seal and a third gasket, the third gasket abuts against a retaining spring, and the pan-plug seal abuts against the third gasket; the pan-plug seal is limited by a retaining ring unit.

8. The piston sealing structure for a liquid-driven piston compressor according to claim 2, characterized in that: The retaining ring unit comprises a retaining ring and a supporting sleeve.

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