A piston sealing structure for a liquid-driven piston compressor

Abstract

The present invention discloses a piston sealing structure for a liquid-driven piston compressor, comprising: 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 so that: when the first sealing structure is performing a sealing operation, 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. The piston sealing structure of the liquid-driven piston compressor designed by the present invention utilizes the alternating operation of the 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.

Description

Technical Field

[0001] The present 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 in a hydrogen refueling station—the compressor, hydrogen storage container, and hydrogenator—the compressor plays the important role of pressurizing the hydrogen source at the station. The performance of the compressor directly determines the operational status 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 significant differences in their specific working principles, structures, etc., and their performance is also different. Therefore, how to select and use the two compressors based on the performance of the compressor and the specific conditions of the hydrogen refueling station is of great significance to the construction and operation of the hydrogen refueling station. Liquid-driven piston compressors have attracted increasing attention due to their advantages such as load start and stop, high volumetric efficiency, few wearing parts, and simple maintenance. They will be one of the main applications of hydrogen compressors in hydrogen refueling stations in the future.

[0003] A hydraulic-driven piston compressor is a novel compression method that uses an electro-hydraulic drive instead of the crank-connecting rod of traditional reciprocating piston compressors. Hydraulic oil drives the oil piston, which, through the piston rod, drives the gas piston to compress and exhaust the working fluid. The combination of a combined cylinder block and combined piston results in dynamic seals in hydrogen compressors of this structure. Therefore, the reliability and service life of the seal structure severely restrict the lifespan and operational safety of the hydraulic-driven piston compressor.

[0004] A hydraulic-driven piston compressor is a new type of compression system that uses an electro-hydraulic drive instead of the crank-connecting rod of a traditional reciprocating piston compressor. Hydraulic oil drives the movement of an oil piston, which, through a piston rod, drives the movement of a gas piston to compress and exhaust the working fluid. The combination of a combined cylinder and piston ensures that the seals of this hydrogen compressor structure are all dynamic. Therefore, ensuring sealing performance at all locations to isolate the hydraulic oil and hydrogen from each other and prevent leakage is a key issue for this type of compressor.

[0005] The traditional piston ring sealing structure is used in liquid-driven piston compressors. Its safety cannot be effectively guaranteed under high-pressure differential working environment. In addition, hydrogen leakage will greatly reduce the economic efficiency of liquid-driven piston compressors.

[0006] Currently, the predominant sealing structure used in liquid-driven piston compressors on the market is a diaphragm seal. However, the diaphragm seal has a relatively thin edge, which can lead to increased wear over time without oil lubrication. If the diaphragm seal lip is thickened, the interference fit with the cylinder of the liquid-driven piston compressor will increase the risk of structural failure due to the limited yield strength of the diaphragm seal material. Therefore, the actual service life of diaphragm seals in existing technical solutions is less than 1,000 hours, significantly lower than the expected lifespan of 8,000 hours for liquid-driven piston compressors in hydrogen refueling stations.

[0007] There are also technical solutions currently using an axially distributed multi-channel pan-seal structure 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-seals simultaneously contact the inner wall of the cylinder during the reciprocating motion of the piston and cause wear. Therefore, when the front pan-seal is working normally, the rear pan-seal will also be worn. Therefore, the effect of improving the service life of the piston seal of the liquid-driven piston compressor is limited, and the expected service life is still unable to 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 a sealing operation, the second sealing structure will not produce wear between the second sealing structure and the inner wall surface of the cylinder as the piston moves back and forth periodically; 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 sequentially installed in the mounting groove respectively; 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 in contact 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 that matches the first gasket, and the end face of the mounting groove is also arranged to be a conical surface that matches the second gasket.

[0015] A more preferred technical solution is to provide annular notches on the inner ring and outer ring of the second gasket, respectively, with the annular notches on both sides being 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 seal and a third gasket, 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.

[0018] A more preferred technical solution is that the retaining ring unit includes a retaining ring and a support 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 alternating 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 Diagram of the piston seal structure of the liquid-driven piston compressor of the present invention;

[0023] Figure 2 Diagram of the second seal structure 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 according to the present invention.

[0025] Illustration: 1- retaining ring, 2- support sleeve, 3- dirt retaining ring, 4- general plug seal, 5- third gasket, 6- retaining ring, 7- spring, 8- conical gasket, 9- double conical gasket, 10- support 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 understood 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 this 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 expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to a fixed connection, an indirect connection via an intermediate medium, internal communication between two components, or an interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0029] In the description of this 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 accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

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

[0032] Embodiment 1:

[0033] See also Figure 1A piston sealing structure for a liquid-driven piston compressor comprises: 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 a sealing operation, the second sealing structure will not produce wear between the second sealing structure and the inner wall surface of the cylinder as the piston moves back and forth periodically; 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 sequentially installed in the mounting groove respectively; and are limited by a retaining ring unit.

[0036] When the first Variseal seal is operating normally, the second seal does not provide sealing, preventing simultaneous wear. When the first Variseal seal fails, the second seal, compressed by gas pressure, compensates for radial clearance and achieves a complete seal. This increases the reliability and service life of the seal, thereby enhancing 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 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 in contact with the sealing ring and the retaining spring.

[0038] The sealing ring includes a first washer and a second washer. The first washer is a convex conical washer with the conical surface positioned on the side facing the second washer. The second washer is a double-conical washer that mates with the first washer. The end surface of the mounting groove is also configured as a conical surface that mates with the second washer. Annular notches are defined on the inner and outer rings of the second washer, with the two notches arranged diagonally. The annular notch on the outer ring of the second washer is located closer to the first washer.

[0039] The double-cone gasket 9 in the second sealing structure of the present invention is designed to have annular gaps on both sides, such as Figure 2As shown, the conical surfaces on either side cooperate with the piston 11 and conical washers 8 on either side. Conical washers 8 are connected to retaining springs 6 via springs 7. The initial force of spring 7 ensures that conical washers 8 and bi-conical washers 9 do not move axially, maintaining their operating positions. During normal operation of the first-stage Varisconical seal, gas is sealed in front of the first seal, while the second seal is unaffected by the gas pressure within the cylinder. In the present invention, under the initial force of spring 7, the bi-conical washers in the second seal form a clearance fit with the inner wall of cylinder 12, leaving a small gap between the washers and the inner wall. This ensures that, when the first seal is operating normally, the second seal does not wear against the inner wall of the cylinder due to the periodic reciprocating motion of the piston.

[0040] During the operation of a liquid-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 seal structure is constantly worn due to the friction between the first seal structure and the inner wall of the cylinder. When the wear reaches a certain level, the first seal structure fails. Figure 3 As shown, high-temperature and high-pressure gas leaks through the first sealing structure to the retaining spring 6. 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 of the cylinder 12 to produce an interference fit, thereby achieving a sealing effect.

[0041] This invention employs two sealing structures, a pan-seal and a spring-double-cone washer, designed along the piston axis. When the first seal is operating normally, a gap exists between the second seal and the cylinder wall, preventing it from sealing and causing wear. When the first seal fails, gas leaks into the second seal, where it seals effectively under the influence of gas pressure. These two seals operate alternately, effectively extending the service life of the piston seal in a hydraulically driven piston compressor. Furthermore, if piston length permits, multiple spring-double-cone seals can be added behind the pan-seal, enabling multiple seals to operate simultaneously, significantly extending the seal life of the hydraulically driven piston compressor.

[0042] It should be noted that in this embodiment, the first sealing structure comprises a pan-seal 4 and a third gasket 5. The third gasket abuts the retaining spring, and the pan-seal abuts the third gasket. The pan-seal is held in place by a retaining ring unit, which comprises a retaining ring 1 and a support sleeve 2, with a contamination ring 3 mounted on the support sleeve. In this embodiment, the first sealing structure primarily relies on the pan-seal to achieve its sealing effect. The pan-seal, or pan-seal ring, is a high-performance seal consisting of a special V-shaped spring within a U-shaped ring. Appropriate spring force combined with system gas pressure pushes the sealing lip outward and gently presses against the metal surface being sealed, producing an excellent seal. The spring's actuation can overcome slight eccentricity of the metal mating surfaces and wear of the sealing lip, maintaining the desired 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 principles of the present invention should be included in the scope of protection 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 functioning as a seal, the second sealing structure does not wear against the inner wall of the cylinder due to the periodic reciprocating motion of the piston; when the first sealing structure fails, the second sealing structure expands and deforms under air pressure to function as a seal; The piston is provided with a mounting groove, and the first sealing structure and the second sealing structure are sequentially mounted in the mounting grooves respectively and are limited by a retaining ring unit; 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 in contact with the sealing ring and the retaining spring. 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 that matches the first gasket. The end surface of the mounting groove is also arranged to be a conical surface that matches 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.

2. A piston sealing structure for a liquid-driven piston compressor according to claim 1, characterized in that: The annular notch on the outer ring of the second washer is arranged close to the first washer.

3. The piston sealing structure for a liquid-driven piston compressor according to claim 2, characterized in that: The first sealing structure includes: a pan seal and a third gasket, 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.

4. The piston sealing structure for a liquid-driven piston compressor according to claim 1, characterized in that: The retaining ring unit includes a retaining ring and a supporting sleeve.

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