Combined sealing piston structure of hydraulic drive piston compressor

Abstract

The invention discloses a combined sealing piston structure of a hydraulic drive piston compressor, which comprises a piston main body, two sealing structures and a limiting mechanism are arranged at the end part of the piston main body, 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 first sealing structure firstly plays a role in sealing the inner wall of the air cylinder, and when the first sealing structure plays a role in sealing, a gap exists between the second sealing structure and the inner wall of the air cylinder under the action of the limiting mechanism; when the first sealing structure loses efficacy, the limiting mechanism relieves limitation on the second sealing structure under pushing of air pressure, and the sealing effect is achieved through expansion deformation. According to the piston designed by the invention, the spring plugs are sequentially activated in the working process through the limiting structure, so that the sealing duration of the piston is effectively prolonged, and the safety and economical efficiency of system operation are improved.

Description

Technical Field

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

[0002] The liquid-driven piston compressor is a new type of compression method that uses a pan-seal seal to replace the piston ring seal of the traditional reciprocating piston compressor. It is mainly used in the compression of flammable gases such as hydrogen and air. As the main sealing component on the piston, the effective operating time of the pan-seal determines the operating time of the liquid-driven piston compressor. However, due to the influence of high pressure, high temperature, gas source impurities, interference fit and other factors, the sealing effect of conventional pan-seals is poor and the sealing time is short. High-pressure flammable gases such as hydrogen are prone to explosion after leakage due to their wide flash point range, causing safety problems. In daily use, the frequent start-up and shutdown of the unit due to the pan-seal, manual maintenance and replacement, increase the maintenance and operation costs, and make the unit less economical.

[0003] Traditional reciprocating piston compressors use piston rings to seal the gap between the cylinder and the piston, limiting the amount of blowby from the high-pressure gas in the cylinder to the crankcase. Considering the thermal expansion of metal and the convenience of installation, piston rings generally have cutouts. When the gas is compressed, the high-pressure gas enters the piston groove through the cutout, exerting a circumferential expansion force on the inner wall of the piston ring to stretch the piston ring, so that the piston ring fits tightly against the cylinder wall to achieve the sealing function. Generally, two or three piston rings are arranged on the piston, and the cutouts are staggered at a certain angle to form a labyrinth seal to further reduce leakage.

[0004] Since traditional reciprocating piston compressors use piston rings in high-pressure and oily environments, the opening of the piston ring is filled with oil, resulting in a small amount of leakage. Since hydrogen requires an oil-free working environment, the leakage of the piston ring is greater than 10% when there is no oil lubrication, which is far more than the design allows. In addition, the sealing working environment of the liquid-driven piston compressor has a high pressure difference and heavy load, which causes the sealing components to wear out greatly, resulting in the existing piston sealing time being about 1000 hours, which is far less than the market demand of 4000-8000 hours. Therefore, the current liquid-driven piston compressor mainly uses a pan-seal to seal the gap between the cylinder and the piston, and the pan-seal sealing lip is stretched open by spring tension and gas force, so that the pan-seal sealing lip fits tightly with the cylinder wall to achieve the sealing function.

[0005] During the design process, in order to ensure that the sealing lip of the pan-seal fits tightly against the cylinder wall, the spring tension will make the sealing lip size of the pan-seal larger than the inner wall size of the cylinder, so during the assembly process, the pan-seal and the sealing surface are generally interference fit. When the spring force is large, the interference is large. If the pan-seal is placed in the cylinder for a long time, the spring will yield and deform, resulting in the spring force and gas force being unable to open the pan-seal sealing lip. In order to reduce the leakage, when multiple arrangements of piston rings are used, due to interference fit and thermal expansion, multiple pan-seal lips will be worn at the same time, so that when the pan-seal closest to the gas side fails, multiple pan-seals at the rear are also on the verge of failure. It is impossible to achieve the effect of extending the sealing time through multiple arrangements, so currently liquid-driven piston compressors generally use a single pan-seal for sealing.

[0006] Existing liquid-driven piston compressors generally use a single pan seal for sealing. After a period of use, the pan seal fails due to wear of the pan seal lip. The machine often needs to be disassembled for repair, resulting in high maintenance costs and low overall machine operating efficiency.

[0007] When multiple pan-plug seals are used for sealing, multiple pan-plug seal lips will be worn at the same time due to interference fit, which increases the cost while only slightly improving the sealing time. The problem of simultaneous wear of multiple pan-plug seals cannot be solved, resulting in a short effective operating time of the unit and low work efficiency. Summary of the invention

[0008] The object of the present invention is to provide a combined sealed piston 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 combined sealed piston structure of a liquid-driven piston compressor, comprising:

[0011] A piston body, wherein the end of the piston body is provided with two sealing structures and a limiting mechanism, wherein the two sealing structures are respectively 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;

[0012] The first sealing structure first seals the inner wall of the cylinder. When the first sealing structure plays a sealing role, a gap exists between the second sealing structure and the inner wall of the cylinder due to the action of the limiting mechanism. When the first sealing structure fails, the limiting mechanism releases the restriction on the second sealing structure under the push of air pressure, and expands and deforms to play a sealing role.

[0013] In some embodiments, the piston body is provided with two steps with smaller diameters on the side facing the end, which are the first step and the second step. The second sealing structure is installed on the first step, and the first sealing structure is installed on the second step. The end of the piston body is provided with a retaining ring which serves as a limit.

[0014] In some embodiments, the first sealing structure includes: a first pan-seal, wherein the first pan-seal is provided on the second step.

[0015] In some embodiments, the first sealing structure further includes: a first gasket, which is disposed at the top corner of the second step and abuts against the first pan-plug seal to reduce wear of the first pan-plug seal.

[0016] In some embodiments, the second sealing structure includes a second pan-seal, and the second pan-seal is disposed on the first step.

[0017] In some embodiments, the second pan-seal is provided with an annular limiting groove and an annular receiving groove on the side in contact with the cylinder wall, the limiting groove is arranged between the sealing lip of the second pan-seal and the receiving groove; the size of the limiting groove is larger than the size of the receiving groove; the size of the limiting mechanism is larger than the size of the limiting groove, and the limiting mechanism is configured as follows: when the first sealing structure has not failed, when the limiting mechanism is sleeved in the limiting groove, there is a gap between the sealing lip of the second pan-seal and the inner wall of the cylinder; when the first sealing structure fails, the limiting mechanism is pushed into the receiving groove by air pressure, and at the same time, the sealing lip of the second pan-seal contacts with the inner wall of the cylinder.

[0018] In some embodiments, the limiting mechanism includes an O-ring and a wear-resistant ring, and the wear-resistant ring is a concave opening structure, and the O-ring is wrapped into a whole through the opening structure.

[0019] In some embodiments, the limiting groove and the receiving groove are designed to be an inverted triangle structure.

[0020] In some embodiments, the second sealing structure further includes: a second gasket, which is disposed on the first step and abuts against the second pan-plug seal to reduce wear of the second pan-plug seal.

[0021] In some embodiments, a third step is provided between the second step and the piston end, the diameter of the third step is smaller than the diameter of the second step, and a contamination ring support and a contamination ring are installed on the third step.

[0022] Compared with the prior art, the present invention has the following technical effects:

[0023] (1) The piston designed in the present invention activates the pan-seal in sequence during operation through the limiting structure, thereby effectively extending the piston sealing time and improving the safety and economy of the system operation.

[0024] (2) The wear-resistant ring and the O-ring in the structure designed by the present invention adjust the contact area according to the pressure to prevent the activation failure of the flood seal, and has a wide range of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Structure diagram of liquid-driven piston compressor;

[0026] Figure 2 The piston structure diagram of the hydraulic driven piston compressor;

[0027] Figure 3 Structural diagram of the second pan-seal (not working);

[0028] Figure 4 The second pan-seal (working) structure diagram;

[0029] Figure 5 This is a schematic diagram of the dimensions when the second pan seal is not working;

[0030] Figure 6 This is a schematic diagram of the dimensions of the second pan seal when it is working;

[0031] Illustration: cylinder end cover 1, pressure valve cover 2, water-cooled cylinder liner 3, cylinder 4, bolt 5, air valve 6, piston 7, piston rod 8, retaining ring 9, dirt containment ring support 10, dirt containment ring 11, first flood seal 12, first gasket 13, second flood seal 14, second gasket 15, support ring 16, piston body 17, flood seal body 18, spring 19, receiving groove 20, wear-resistant ring 21, O-ring 22. DETAILED DESCRIPTION

[0032] 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.

[0033] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] The following will be combined Figure 1-Figure 3 , a liquid-driven piston compressor combined sealing piston structure involved in the 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.

[0038] Embodiment 1:

[0039] See also Figure 1-Figure 6 The structure of the liquid-driven piston compressor composed of the liquid-driven piston compressor combined sealing piston structure of the present invention is as follows Figure 1 As shown, it includes a cylinder end cover 1, a compression valve cover 2, a water-cooled cylinder sleeve 3, a cylinder 4, a bolt 5, a gas valve 6, a piston 7, and a piston rod 8. The hydraulic mechanism pushes the piston rod 8 to move and then pushes the piston 7 to compress the gas; when the gas in the cylinder 4 reaches the exhaust pressure, the lower gas valve (exhaust valve) opens, the piston reaches the top dead center position and changes direction to make the piston rod move in the opposite direction together with the piston, and the exhaust process ends and the expansion process begins; when the pressure in the cylinder drops to the suction pressure, the upper gas valve (suction valve) opens and the suction process begins, the piston reaches the bottom dead center position and changes direction to make the piston rod move in the opposite direction together with the piston, and the suction process ends and the compression process begins.

[0040] The present invention designs the piston 7 with multiple sealing mechanisms, such as Figure 2As shown. It includes a retaining ring 9, a support sleeve 10, a dirt-receiving ring 11, a first flood seal 12, a first gasket 13, a second flood seal 14, a second gasket 15, a support ring 16 for preventing the piston from deflecting, and a piston body 17. The structure of the second flood seal 14 is as shown in FIG. Figure 3 As shown, it includes a pan plug body 18, a spring 19, a receiving groove 20, a wear-resistant ring 21, and an O-ring 22.

[0041] The end of the piston body is provided with two sealing structures and a limiting mechanism, the two sealing structures are respectively the first sealing structure and the second sealing structure; the piston body is provided with two steps with smaller diameters on the side facing the end, respectively the first step and the second step, the second sealing structure is installed on the first step, and the first sealing structure is installed on the second step; the end of the piston body is provided with a retaining ring for limiting. A third step is provided between the second step and the end of the piston, the diameter of the third step is smaller than that of the second step, and a dirt ring support and a dirt ring are installed on the third step. The dirt ring is used to collect impurities in the cylinder.

[0042] Among them, the sealing structure close to the end of the piston is the first sealing structure; the first sealing structure first plays a role in sealing the inner wall of the cylinder. When the first sealing structure plays a sealing role, a gap exists between the second sealing structure and the inner wall of the cylinder under the action of the limiting mechanism; when the first sealing structure fails, the limiting mechanism releases the restriction on the second sealing structure under the push of air pressure, and expands and deforms to play a sealing role.

[0043] In some embodiments, the first sealing structure includes: a first pan-seal, the first pan-seal sleeve is arranged on the second step. The first sealing structure also includes: a first gasket, the first gasket is arranged at the top corner of the second step, abuts against the first pan-seal, and is used to reduce the wear of the first pan-seal.

[0044] In some embodiments, the second sealing structure includes a second pan-plug seal and a second gasket, wherein the second gasket is disposed on the first step and abuts against the second pan-plug seal to reduce wear of the second pan-plug seal.

[0045] The second pan-seal is sleeved on the first step. The second pan-seal is provided with an annular limiting groove and an annular receiving groove on the side in contact with the cylinder wall, the limiting groove is arranged between the sealing lip of the second pan-seal and the receiving groove; the size of the limiting groove is larger than the size of the receiving groove; the size of the limiting mechanism is larger than the size of the limiting groove, and the limiting mechanism is configured such that: when the first sealing structure is not invalid, when the limiting mechanism is sleeved in the limiting groove, there is a gap between the sealing lip of the second pan-seal and the inner wall of the cylinder; when the first sealing structure is invalid, the limiting mechanism is pushed into the receiving groove by air pressure, and the sealing lip of the second pan-seal contacts the inner wall of the cylinder.

[0046] If the first pan seal is not invalid and the second pan seal is not working, Figure 3 As shown. Under the action of the elastic force of the spring inside the first pan-seal and the pressure of the gas, the outer diameter of the first pan-seal expands to fit tightly with the inner wall of the cylinder, so that the cylinder remains sealed. In the initial state, the wear-resistant ring 21 and the O-ring 22 of the second pan-seal are in the limit groove. The compressive strength of the O-ring is sufficient to limit the sealing lip of the pan-seal within the inner diameter of the cylinder. The material used is NBR. The maximum outer diameter of the sealing lip of the second pan-seal is limited so that it is always smaller than the inner diameter of the cylinder. The wear-resistant ring outside the O-ring is designed as an open structure to prevent the failure of the limiting function due to the friction and deformation of the O-ring with the cylinder after it expands due to heat during movement; when the first pan-seal fails and the high-pressure gas leaks to the second pan-seal, as shown Figure 4 The gas pressure and friction of the high-pressure gas push the O-ring 22 and the wear-resistant ring 21 to the receiving groove 20, and the second flood seal is activated. Under the action of gas force and spring force, the outer wall surface of the sealing lip is tightly fitted with the inner wall of the cylinder to achieve a sealing effect.

[0047] The space between the limit groove and the receiving groove is designed as an inverted triangle structure, which facilitates the gas to push the wear-resistant ring 21 and the O-ring 22 into the receiving groove 20, and prevents the wear-resistant ring 21 and the O-ring 22 from returning to the initial position through friction. When the pan seal is not subjected to external force, the elastic force of the spring inside the pan seal should be sufficient to expand the outer diameter of the pan seal to fit tightly with the inner wall of the cylinder, so that the cylinder remains sealed. As the main friction component, the wear ring is made of PTFE material. The wear ring is designed as a concave structure to increase the contact area with the O-ring.

[0048] According to the different working pressures of the environment in which they are used, the contact surface between the wear ring and the O-ring will also be adjusted accordingly. The higher the pressure, the larger the contact area. To prevent the gas force from being too small to push the wear ring and the O-ring, resulting in the failure of the second flood seal to be activated, or the friction of the wear ring is too large, pushing the wear ring and the O-ring into the storage groove, activating the second flood seal in advance, and failing to activate in sequence and extend the sealing time; considering that the gas will be heated to 200°C during the operation of the unit, the contamination ring is made of CFRP material, which has the advantages of low density, small thermal expansion coefficient, and good heat-resistant ablation performance.

[0049] The following example illustrates the process of the limiting mechanism being blown from the limiting slot to the receiving slot;

[0050] During the design, the radius size of the groove where the O-ring is located when not working is 51mm, the radius size of the O-ring is 50*56mm, the radius size of the wear-resistant ring is 56*59.5mm, the radius size of the storage groove is 50.1mm, and the radius of the cylinder is 60mm.

[0051] Consider the O-ring and the wear ring as a whole (limiting mechanism), and the size of the limiting mechanism is 50*59.5mm. Since the O-ring is a plastic structure, deformation is allowed. At the same time, the wear ring is an open structure, which also allows deformation.

[0052] When the VanSeal is not in operation, Figure 5 The size of the initial position groove is larger than the inner diameter of the limiting mechanism (51-50=1mm), causing the limiting mechanism to be propped up by 1mm. However, the radius of the cylinder is 60mm (59.5+1=60.5>60), so at this time the limiting mechanism itself is compressed by 0.5mm and expands outward by 0.5mm to fit closely with the cylinder wall.

[0053] When the FanSeal is in working state, Figure 6 The size of the storage groove is larger than the inner diameter of the limiting mechanism (50.1-50=0.1mm), which causes the limiting mechanism to be propped up by 0.1mm. However, the inner diameter of the cylinder is 60mm (59.5+0.1=59.6>60), so the limiting mechanism cannot fit with the cylinder wall. At the same time, due to the interference fit, the limiting mechanism is fixed in the storage groove and will not move.

[0054] 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 combined sealed piston structure for a liquid-driven piston compressor, characterized in that: include: A piston body, wherein the end of the piston body is provided with two sealing structures and a limiting mechanism, wherein the two sealing structures are respectively 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 first sealing structure first seals the inner wall of the cylinder. When the first sealing structure plays a sealing role, a gap exists between the second sealing structure and the inner wall of the cylinder due to the action of the limiting mechanism. When the first sealing structure fails, the limiting mechanism releases the restriction on the second sealing structure under the push of air pressure, and expands and deforms to play a sealing role.

2. A combined sealed piston structure for a liquid-driven piston compressor according to claim 1, characterized in that: The piston body is provided with two steps with smaller diameters on one side facing the end, which are the first step and the second step. The second sealing structure is installed on the first step, and the first sealing structure is installed on the second step. The end of the piston body is provided with a retaining ring which serves as a limit.

3. A combined sealed piston structure for a liquid-driven piston compressor according to claim 2, characterized in that: The first sealing structure comprises: a first flood seal, wherein the first flood seal sleeve is arranged on the second step.

4. A combined sealed piston structure for a liquid-driven piston compressor according to claim 3, characterized in that: The first sealing structure further includes: a first gasket, which is arranged at the top corner of the second step and abuts against the first flood seal to reduce wear of the first flood seal.

5. The combined sealed piston structure of a liquid-driven piston compressor according to claim 2, characterized in that: The second sealing structure comprises a second flood seal, and the second flood seal sleeve is arranged on the first step.

6. A combined sealed piston structure for a liquid-driven piston compressor according to claim 5, characterized in that: The second pan-seal is provided with an annular limiting groove and an annular receiving groove on the side in contact with the cylinder wall, the limiting groove is arranged between the sealing lip of the second pan-seal and the receiving groove; the size of the limiting groove is larger than the size of the receiving groove; the size of the limiting mechanism is larger than the size of the limiting groove, and the limiting mechanism is configured as follows: when the first sealing structure has not failed, when the limiting mechanism is sleeved in the limiting groove, there is a gap between the sealing lip of the second pan-seal and the inner wall of the cylinder; when the first sealing structure fails, the limiting mechanism is pushed into the receiving groove by air pressure, and at the same time the sealing lip of the second pan-seal contacts the inner wall of the cylinder.

7. A combined sealed piston structure for a liquid-driven piston compressor according to claim 6, characterized in that: The limiting mechanism comprises an O-ring and a wear-resistant ring. The wear-resistant ring is a concave opening structure, and the O-ring is wrapped into a whole through the opening structure.

8. The combined sealed piston structure of a liquid-driven piston compressor according to claim 6, characterized in that: The space between the limiting groove and the receiving groove is designed to be an inverted triangle structure.

9. The combined sealed piston structure of a liquid-driven piston compressor according to claim 5, characterized in that: The second sealing structure further includes: a second gasket, which is arranged on the first step and abuts against the second pan-plug seal to reduce wear of the second pan-plug seal.

10. The combined sealed piston structure of a liquid-driven piston compressor according to claim 5, characterized in that: A third step is provided between the second step and the piston end, the diameter of the third step is smaller than the diameter of the second step, and a dirt containing ring support and a dirt containing ring are installed on the third step.

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