Double-acting cylinder gas piston structure of liquid-driven hydrogen compressor

Abstract

The utility model discloses a kind of double-acting cylinder air piston structures of liquid-driven hydrogen compressor, double-acting cylinder air piston structure includes piston rod, air piston, baffle ring, snap ring, elastic baffle ring, by setting multiple layers ladder shaft structure on piston rod, baffle ring is embedded in the second groove on piston rod, baffle ring and first boss are respectively positioned to the air piston assembled in axial two sides, then utilize snap ring to baffle ring limit, elastic baffle ring one side is embedded in third groove and is positioned to snap ring, to form the air piston combination structure of mutual limit, compared with the air piston of conventional structure thread connection is more convenient to disassemble and assemble, whole machine does not need to disassemble, only need to remove air end cover after sequentially removing elastic baffle ring, snap ring, baffle ring, air piston split structure in the spare part required to replace, under the premise of meeting sealing performance, maintenance replacement convenience is greatly improved, save cost, with broad application prospect.

Description

Technical Field

[0001] This utility model relates to the technical field of piston structure in a liquid-driven hydrogen compressor. More specifically, this utility model relates to a double-acting cylinder piston structure for a liquid-driven hydrogen compressor. Background Technology

[0002] Existing liquid-driven hydrogen compressors use an axial fit between the piston and piston rod, employing a shaft retaining ring to limit the piston's movement. Therefore, the material and load-bearing capacity of the retaining ring are critical, and it is typically secured with threads to prevent loosening. In practical operation, the complex working conditions can easily lead to piston loosening, affecting the lifespan of the seals and causing damage to the cylinder's inner wall. Furthermore, replacing the seals requires disassembling parts of the compressor cylinder, making the operation complex and difficult to perform on-site, such as at hydrogen refueling stations. Summary of the Invention

[0003] One object of this invention is to solve at least the problems described above and to provide at least the advantages that will be explained later.

[0004] Another objective of this invention is to provide a double-acting cylinder piston structure for a liquid-driven hydrogen compressor, in order to solve the technical problem that the piston structure in the prior art is fixed by bolts, resulting in a poor service life.

[0005] To achieve these objectives and other advantages according to this invention, this invention provides a double-acting cylinder piston structure for a liquid-driven hydrogen compressor, comprising: The piston rod has a working end for compression at its head and a driving end at its tail. The working end is machined axially to form a multi-layered stepped shaft structure with the diameter of each layer increasing sequentially from the head to the tail. The number of stepped shaft layers is 2-3. The stepped shaft with the largest diameter layer is offset from the outer wall of the adjacent piston rod to form a first boss. A first groove is formed radially inward on the side near the first boss. A sealing ring is provided in the first groove. A second boss is machined radially outward on the head side of the stepped shaft with the smallest diameter layer. The outer diameter of the second boss is not greater than the outer diameter of the adjacent stepped shaft layer. A second groove is formed between the end faces of the second boss and the adjacent stepped shaft layer. The pneumatic piston is a split assembly structure fitted onto the piston rod, comprising a right split piston and a left split piston arranged sequentially towards the first boss. The right split piston abuts against the first boss. An annular groove is formed on the outer ring of the right split piston facing the left split piston. A convex ring is fitted on the end of the left split piston facing the annular groove. In the axial direction of the piston rod, the length of the convex ring is less than the depth of the annular groove to form a sealing groove on one side of the tail end of the annular groove. The side of the left split piston facing the second boss and the side of the second groove away from the second boss are arranged radially flush. Support rings are also fitted on the outer sides of the right split piston and the left split piston respectively. The retaining ring is a split structure. The radial inner side of the retaining ring is fitted with the second groove and embedded in the second groove. The outer diameter of the retaining ring is larger than the diameter of the stepped shaft of the corresponding layer. The side of the retaining ring facing the first boss abuts against the corresponding side end face of the left split piston. The outer side of the retaining ring is provided with a third groove radially inward. A retaining ring, which surrounds the outside of the retaining ring, is used to limit the retaining ring in the radial direction; An elastic retaining ring, which is fitted onto the third groove, is used to axially limit the retaining ring of the piston. A closed seal is installed inside a sealing groove.

[0006] Preferably, the second boss includes a tooth structure that is circumferentially spaced, and the tooth structure axially limits the end face of the head of the retaining ring.

[0007] Preferably, the retaining ring has an L-shaped cross-section in the axial section, including an axial portion and a radial portion. The radial portion abuts against the corresponding end face of the left split piston. The third groove is formed on the axial portion, and one side of the tail end of the retaining ring abuts against the radial portion.

[0008] Preferably, the stepped shaft has three layers, namely the first layer, the second layer, and the third layer stepped shaft from the smallest diameter end to the largest diameter end. The left split piston is sleeved on the outside of the second layer stepped shaft, and the right split piston is sleeved on the outside of the second layer stepped shaft and the third layer stepped shaft. A fourth groove is formed radially inward at the end of the second layer stepped shaft that abuts against the third layer stepped shaft, and a sealing ring is provided in the fourth groove.

[0009] Preferably, the left split piston has one support ring on its outer side, and the right split piston has two support rings on its outer side.

[0010] Preferably, the elastic retaining ring has an opening in the circumferential direction, and the elastic retaining ring extends radially outward on the side opposite to the opening to form an arc-shaped segment.

[0011] Preferably, a limiting ring channel is provided at intervals on the outer side wall of the piston rod near the first boss. The bottom of the limiting ring channel is integrally formed and connected to the corresponding position of the side wall of the piston rod. There is a gap between the side of the limiting ring channel near the first boss and the right split piston. In the radial direction, a limiting ring cavity is formed between the limiting ring channel and the side wall of the piston rod. An axial air passage is opened from the outside to the inside at the center of the smaller diameter end of the piston rod. Multiple radial air passages are opened radially outward at the bottom of the axial air passage. The radial air passages are evenly spaced in the circumferential direction. An air outlet is provided through the radial outer side of the radial air passage. The air outlet is connected to the bottom of the limiting ring cavity. A rubber ring is filled in the limiting ring cavity. The radial thickness of the rubber ring is not less than the width of the limiting ring cavity. An arc-shaped groove is provided along the annular depression at the bottom of the rubber ring. The thickness of the rubber ring is less than the distance between the bottom of the limiting ring cavity and the right split piston.

[0012] This utility model has at least the following beneficial effects: This utility model discloses a double-acting cylinder piston structure for a liquid-driven hydrogen compressor, comprising a piston rod, a piston, a retaining ring, a retaining ring, and an elastic retaining ring. By setting a multi-layered stepped shaft structure on the piston rod, the retaining ring is embedded in the second groove on the piston rod. The retaining ring and the first boss limit the assembled piston on both sides axially. Then, the retaining ring provides circumferential limitation. The elastic retaining ring is embedded in the third groove on one side, further limiting the retaining ring axially. This forms a mutually limiting piston assembly structure. The overall structure is easier to assemble and disassemble than conventional threaded piston structures, eliminating the need for a complete unit. Disassembly is simple: just remove the gas end cover, and from the end of the hydraulically driven compressor, sequentially remove any part of the gas piston components, including the elastic retaining ring, snap ring, retaining ring, and the split gas piston structure, until the replacement part is found. After replacement, reassemble. This significantly improves maintenance and replacement convenience while maintaining sealing performance, saving costs. Additionally, a rubber ring is installed at the bottom of the gas piston, and the piston rod has interconnected axial and radial air passages and a limiting ring cavity. This design supports the deformation of the rubber ring and, together with the closed seal and sealing ring, provides support to the gas piston from different directions, enhancing the operational stability of the gas piston structure and improving operational performance. This novel double-acting cylinder gas piston structure is suitable for hydraulically driven piston compressors and has broad application prospects in hydrogen energy, oilfield, and other booster equipment.

[0013] Other advantages, objectives and features of this invention will be partly apparent from the following description, and partly understood by those skilled in the art through study and practice of this invention. Attached Figure Description

[0014] Figure 1 This is an axial cross-sectional view of a gas piston structure according to an embodiment of the present invention; Figure 2 This utility model Figure 1 A top view of the piston structure near the cylinder end cover. Figure 3 This is an axial sectional view of the gas piston structure according to another embodiment of the present invention; Figure 4 For the present utility model Figure 3 Exploded view of a gas piston structure; Figure 5 This is an axial cross-sectional view of the airway configuration according to another embodiment of the present invention.

[0015] The following are the reference numerals in the instruction manual's attached diagrams: 1. Retaining ring, 2. Elastic retaining ring, 3. Snap ring, 4. Gas piston, 5. Piston rod, 6. Sealing ring, 7. Support ring, 8. Closed seal, 9. Sealing ring, 10. Axial air passage, 11. Radial air passage, 12. Limiting ring passage, 13. Limiting ring cavity, 14. Rubber ring, 15. Air outlet, 16. Arc-shaped recess. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0017] It should be noted that in the description of this utility model, the terms "horizontal", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0018] like Figure 1-5 As shown, this utility model provides a double-acting cylinder piston structure for a liquid-driven hydrogen compressor, comprising: The piston rod 5 has a working end for compression at its head and a driving end at its tail. The working end is machined axially to form a multi-layer stepped shaft structure with the diameter of each layer increasing sequentially from the head to the tail. The number of stepped shaft layers is 2-3. The stepped shaft with the largest diameter layer is offset from the outer wall of the adjacent piston rod 5 to form a first boss. A first groove is formed radially inward on the side near the first boss. An O-ring seal 6 is provided in the first groove to prevent gas from leaking from the rod chamber to the rodless chamber. A second boss is machined radially outward on the head side of the stepped shaft with the smallest diameter layer. The outer diameter of the second boss is not greater than the outer diameter of the adjacent stepped shaft layer. A second groove is formed between the end faces of the second boss and the adjacent stepped shaft layer. The air piston 4 is a split assembly structure that is sleeved on the piston rod 5, which facilitates the installation of the closed seal 8. It includes a right split piston and a left split piston arranged sequentially towards the first boss. The right split piston abuts against the first boss. The outer ring of the right split piston facing the left split piston has an annular groove. The left split piston has a convex ring at the end facing the annular groove. In the axial direction of the piston rod 5, the length of the convex ring is less than the depth of the annular groove, so as to form a sealing groove on one side of the tail end of the annular groove. The side of the left split piston facing the second boss and the side of the second groove away from the second boss are arranged radially flush. The outer sides of the right split piston and the left split piston are also fitted with support rings 7 respectively. The retaining ring 1 is a split structure. The radial inner side of the retaining ring 1 is fitted with the second groove and embedded in the second groove. The outer diameter of the retaining ring 1 is larger than the diameter of the stepped shaft of the corresponding layer. The side of the retaining ring 1 facing the first boss abuts against the corresponding side end face of the left split piston. The outer side of the retaining ring 1 is provided with a third groove radially inward. A retaining ring 3 is disposed on the outside of the retaining ring 1 and is used to limit the retaining ring 1 in the radial direction; The elastic retaining ring 2 is sleeved on the third groove and is used to limit the circumferential movement of the piston 4 to the retaining ring 3. The retaining ring 1 cooperates with the elastic retaining ring 2 to limit the circumferential movement of the retaining ring 3. The retaining ring 3 is a split structure and needs to be cut after the whole assembly is completed.

[0019] The closed seal 8 is installed in the sealing groove as the main sealing structure.

[0020] During actual operation, the piston 4 is subjected to axial force on the retaining ring 1 to prevent it from falling off, while the retaining ring 3 is not subjected to force and only provides circumferential restraint to prevent it from falling off. The retaining ring 3 does not contact the left side of the piston 4, leaving a gap. After opening the cylinder end cover, the assembly sequence is as follows: piston rod 5, sealing ring 6, right split piston, closed seal 8, left split piston, retaining ring 1, retaining ring 3, shaft elastic retaining ring 2, and support ring 7. Then, the cylinder end cover is screwed on, and the cylinder does not need to be disassembled as a whole.

[0021] The double-acting cylinder piston 4 structure of the liquid-driven hydrogen compressor of this utility model includes a piston rod 5, a piston 4, a retaining ring 1, a retaining ring 3, and an elastic retaining ring 2. By setting a multi-layer stepped shaft structure on the piston rod 5, the retaining ring 1 is embedded in the second groove on the piston rod 5. The retaining ring 1 and the first boss limit the assembled piston 4 on both sides in the axial direction. Then, the retaining ring 3 is used to limit the retaining ring 1 circumferentially. The elastic retaining ring 2 is embedded in the third groove on one side and then limits the retaining ring 3 axially, thereby forming a mutually limiting piston 4 assembly. The integrated structure of the piston 4 is easier to disassemble and assemble than the conventional threaded connection structure. After removing the gas end cover, the piston 4 parts can be removed sequentially from the end of the liquid-driven compressor. The elastic retaining ring 2, retaining ring 3, retaining ring 1, and any part of the piston 4 split structure can be removed to the part that needs to be replaced. After replacement, the parts can be reassembled. Under the premise of meeting the sealing performance, the convenience of maintenance and replacement is greatly improved, and the cost is saved. The double-acting cylinder piston 4 structure of this utility model is suitable for liquid-driven piston compressors and can be used in booster equipment in hydrogen energy, oil fields and other fields, with broad application prospects.

[0022] In another technical solution, such as Figure 1-4 As shown, the second boss includes a toothed structure evenly spaced along the circumference, which axially limits the end face of the head of the retaining ring 1. The second boss facilitates operation and observation for alignment during installation, and reduces production costs.

[0023] In another technical solution, combined with Figure 3-4 As shown, the retaining ring 1 has an L-shaped cross-section in the axial section, including an axial portion and a radial portion. The radial portion abuts against the corresponding end face of the left split piston. The third groove is formed on the axial portion, and one side of the tail end of the retaining ring 3 abuts against the radial portion. The retaining ring 1 is made into an L-shaped stepped form. Its function is to increase the relative area of ​​the piston 4 impacting the retaining ring 1 during the reciprocating motion of the piston and piston 5 in actual operation, completely avoiding the contact surface of the retaining ring 3. The retaining ring 3 is not actually subjected to force, thereby ensuring the stability between the mutually limiting structures and improving service life.

[0024] In another technical solution, such as Figure 1-4 As shown, the stepped shaft has three layers, namely the first layer, the second layer, and the third layer stepped shaft from the smallest diameter end to the largest diameter end. The left split piston is sleeved on the outside of the second layer stepped shaft, and the right split piston is sleeved on the outside of the second layer stepped shaft and the third layer stepped shaft. A fourth groove is opened radially inward at the end of the second layer stepped shaft that abuts against the third layer stepped shaft, and a sealing ring 9 is provided in the fourth groove.

[0025] The three-tiered shaft is designed to distribute the impact force on the right split piston on two tiered surfaces. This facilitates the radial depth of the annular groove between the left and right split pistons, thereby increasing the radial dimension of the closed seal 8 and enhancing its elastic support and sealing performance on the left split piston side, right split piston side, and cylinder wall contact side.

[0026] In another technical solution, such as Figure 1-4 As shown, the left split piston has one support ring 7 on its outer side, and the right split piston has two support rings 7 on its outer side. By making the axial dimension of the left split piston shorter, the overall axial length of the piston 4 is reduced while ensuring airtightness and the telescopic movement performance of the piston 4, thus increasing the compression space.

[0027] In another technical solution, such as Figure 1-4 As shown, the elastic retaining ring 2 has an opening in the circumferential direction. The elastic retaining ring 2 extends radially outward on the side opposite to the opening to form an arc-shaped segment, which tightens the circumferential opening and strengthens the circumferential elastic fastening force on the retaining ring 1.

[0028] In another technical solution, such as Figure 5 As shown, a limiting ring channel 12 is provided at intervals on the outer side wall of the piston rod 5 near the first boss. The bottom of the limiting ring channel 12 is integrally formed and connected to the corresponding position of the side wall of the piston rod 5. In the radial direction, a limiting ring cavity 13 is formed between the limiting ring channel 12 and the side wall of the piston rod 5. A rubber ring 14 is filled in the limiting ring cavity 13. The radial thickness of the rubber ring 14 is equal to or slightly larger than the width of the limiting ring cavity 13, but to ensure that the rubber ring 14 can be smoothly installed into the limiting ring cavity 13 from left to right (lubricating oil can also be used during assembly). The center of the smaller diameter end of the piston rod 5 is axially... An axial air passage 10 is provided inside. Multiple radial air passages 11 are provided radially outward from the bottom of the axial air passage 10. The radial air passages 11 are evenly spaced in the circumferential direction. An air outlet 15 is provided on the radial outer side of the radial air passage 11. The air outlet 15 is connected to the bottom of the limiting ring cavity 13. An arc-shaped groove 16 is provided along the bottom of the rubber ring 14, that is, the side facing the bottom of the limiting ring cavity 13. The axial length of the rubber ring 14 is less than the distance between the bottom of the limiting ring cavity 13 and the right split piston. There is a gap between the side of the limiting ring groove 12 near the first protrusion and the right split piston to avoid direct contact.

[0029] When the piston rod 5 moves to the left and compresses the gas in the left cylinder chamber, some of the high-pressure gas enters from the axial passage 10, then passes through the radial passage 11 and the outlet 15, reaching the bottom of the limiting ring cavity 13 (i.e., Figure 5On the right side), the arc-shaped groove 16 of the rubber ring 14 is also filled with high-pressure gas, which exerts a force on the rubber ring 14 to the left, that is, towards the right split piston, and provides a leftward support to the right split piston. Thus, when the gas piston 4 works to the left, it can provide supplementary support and sealing for the closed seal 8 (main seal). The closed seal 8, the sealing ring 6, and the rubber ring 14 act on the right split piston from multiple directions. The limiting ring channel 12 itself has a gap with the right split piston, and under normal operation, it will not exert any force on the gas piston 4. At the same time, when the rubber ring 14 is subjected to a leftward force, it undergoes radial expansion deformation to ensure the sealing of the limiting ring cavity 13. Preferably, a chamfer is provided at the bottom of the limiting ring cavity 13 near the radially outer end. The distance between the left side of the chamfer and the right split piston is set to be equal to the axial thickness of the rubber ring 14. The chamfer serves two purposes: limiting the installation of the rubber ring and guiding the airflow. Alternatively, the radial air passage can be configured as an arc-shaped guide to the air outlet, which, together with the chamfer, better aligns with the arc-shaped concave passage. During assembly, before installing the air piston 4, the rubber ring 14 is first inserted into the limiting ring cavity 13, not exceeding the radial surface where the first boss is located, and then the air piston 4 and other components are installed step by step.

[0030] A method for using a double-acting cylinder piston structure in a liquid-driven hydrogen compressor includes the following steps: S1. The sealing ring 6 is assembled in the first groove on the piston rod 5; S2. The right split piston is fitted onto the stepped shaft from the side with the smaller diameter toward the first boss. The right split piston abuts against the first boss and its radial inner side fits against the outer wall of the stepped shaft at the corresponding position. Then, the closed seal 8 is installed in the sealing groove. Next, the left split piston is fitted onto the stepped shaft from the side with the smaller diameter toward the right split piston, so that the left split piston and the right split piston are spliced ​​into one piece, and the gas piston 4 is fully assembled. At this time, the end face of the left split piston facing away from the first boss and the adjacent side wall of the second groove are located on the same radial section. S3. The retaining ring 1 is assembled in the second groove, and then the retaining ring 3 is sleeved on the outside of the retaining ring 1. At this time, the side of the retaining ring 3 facing away from the first boss is located on the same radial section as the adjacent side wall of the third groove. S4. Insert the elastic retaining ring 2 into the third groove to complete the assembly of the entire gas piston 4 structure.

[0031] Replacing the seals (vulnerable parts) on the piston 4 of other double-acting cylinders requires disassembling the entire compressor end cover, cylinder, piston 4, and other parts. This places high demands on the on-site operating conditions (limited space, numerous tools required, etc.) and results in a long maintenance and replacement time of approximately 8-10 hours. This structure only requires the removal of the end cover and piston 4, has lower requirements on on-site conditions, and the disassembly and assembly time is approximately 2-3 hours. When applied to double-acting compressors, this structure can increase the compressor's compressed gas displacement by approximately 1.5 times while keeping parameters such as cylinder bore and number of compression stages unchanged.

[0032] The gas piston structure of this utility model is easy to disassemble and assemble. The gas piston 4 and piston rod 5 are well aligned in the cylinder. In addition to sealing and ensuring the pressure difference between the left and right ends of the gas piston 4, the sealing ring 6 can also compress and support the gas piston 4 with its own rubber material, ensuring that the gas piston 4 and piston rod 5 are on the same axis, reducing the wear of the support ring 7 and the closed seal 8, thereby improving the service life of the seals, reducing vibration, and ensuring the stable operation of the equipment.

[0033] Although the embodiments of this utility model have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this utility model. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A double-acting cylinder piston structure for a liquid-driven hydrogen compressor, characterized in that, include: The piston rod has a working end for compression at its head and a driving end at its tail. The working end is machined axially to form a multi-layered stepped shaft structure with the diameter of each layer increasing sequentially from the head to the tail. The number of stepped shaft layers is 2-3. The stepped shaft with the largest diameter layer is offset from the outer wall of the adjacent piston rod to form a first boss. A first groove is formed radially inward on the side near the first boss. A sealing ring is provided in the first groove. A second boss is machined radially outward on the head side of the stepped shaft with the smallest diameter layer. The outer diameter of the second boss is not greater than the outer diameter of the adjacent stepped shaft layer. A second groove is formed between the end faces of the second boss and the adjacent stepped shaft layer. The pneumatic piston is a split assembly structure fitted onto the piston rod, comprising a right split piston and a left split piston arranged sequentially towards the first boss. The right split piston abuts against the first boss. An annular groove is formed on the outer ring of the right split piston facing the left split piston. A convex ring is fitted on the end of the left split piston facing the annular groove. In the axial direction of the piston rod, the length of the convex ring is less than the depth of the annular groove to form a sealing groove on one side of the tail end of the annular groove. The side of the left split piston facing the second boss and the side of the second groove away from the second boss are arranged radially flush. Support rings are also fitted on the outer sides of the right split piston and the left split piston respectively. The retaining ring is a split structure. The radial inner side of the retaining ring is fitted with the second groove and embedded in the second groove. The outer diameter of the retaining ring is larger than the diameter of the stepped shaft of the corresponding layer. The side of the retaining ring facing the first boss abuts against the corresponding side end face of the left split piston. The outer side of the retaining ring is provided with a third groove radially inward. A retaining ring, which surrounds the outside of the retaining ring, is used to limit the retaining ring in the radial direction; An elastic retaining ring, which is fitted onto the third groove, is used to axially limit the retaining ring of the piston. A closed seal is installed inside a sealing groove.

2. The double-acting cylinder piston structure of the liquid-driven hydrogen compressor as described in claim 1, characterized in that, The second boss includes a tooth structure that is evenly spaced along the circumference, which axially limits the end face of the head of the retaining ring.

3. The double-acting cylinder piston structure of the liquid-driven hydrogen compressor as described in claim 1, characterized in that, The retaining ring has an L-shaped cross-section in the axial section, including an axial part and a radial part. The radial part abuts against the corresponding end face of the left split piston. The third groove is opened on the axial part, and one side of the tail end of the retaining ring abuts against the radial part.

4. The double-acting cylinder piston structure of the liquid-driven hydrogen compressor as described in claim 1, characterized in that, The stepped shaft has three layers, namely the first layer, the second layer, and the third layer stepped shaft from the smallest diameter end to the largest diameter end. The left split piston is sleeved on the outside of the second layer stepped shaft, and the right split piston is sleeved on the outside of the second layer stepped shaft and the third layer stepped shaft. A fourth groove is opened radially inward at the end of the second layer stepped shaft that abuts against the third layer stepped shaft, and a sealing ring is provided in the fourth groove.

5. The double-acting cylinder piston structure of the liquid-driven hydrogen compressor as described in claim 1, characterized in that, The left split piston has one support ring on its outer side, and the right split piston has two support rings on its outer side.

6. The double-acting cylinder piston structure of the liquid-driven hydrogen compressor as described in claim 1, characterized in that, The elastic retaining ring has an opening in the circumferential direction, and the elastic retaining ring extends radially outward on the side opposite to the opening to form an arc-shaped segment.

7. The double-acting cylinder piston structure of the liquid-driven hydrogen compressor as described in claim 1, characterized in that, A limiting ring is provided at intervals on the outer side wall of the piston rod near the first boss. The bottom of the limiting ring is integrally formed and connected to the corresponding position of the side wall of the piston rod. There is a gap between the side of the limiting ring near the first boss and the right split piston. In the radial direction, a limiting ring cavity is formed between the limiting ring and the side wall of the piston rod. An axial air passage is opened from the outside to the inside at the center of the smaller diameter end of the piston rod. Multiple radial air passages are opened radially outward at the bottom of the axial air passage. The radial air passages are evenly spaced in the circumferential direction. An air outlet is provided through the radial outer side of the radial air passage. The air outlet is connected to the bottom of the limiting ring cavity. A rubber ring is filled in the limiting ring cavity. The radial thickness of the rubber ring is not less than the width of the limiting ring cavity. An arc-shaped groove is provided along the annular depression at the bottom of the rubber ring. The thickness of the rubber ring is less than the distance between the bottom of the limiting ring cavity and the right split piston.

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