Compressor

Abstract

A compressor (10) comprises: a cylinder (21) that has a cylinder chamber (31); a piston (27) that reciprocates inside the cylinder (21); a head cover (41) that closes one end surface of the cylinder (21); a head cover presser (61) that is disposed on the side opposite to the cylinder (21) with respect to the head cover (41); and binding tools (15) that connect the head cover presser (61) and the cylinder (21) and biases the head cover presser (61) and the head cover (41) toward the cylinder (21).

Description

Compressor

[0001] The present invention relates to a compressor used to compress a fluid such as hydrogen.

[0002] A reciprocating compressor has been proposed in which the end face of the cylinder is blocked by a block, and the block has an intake valve and a discharge valve inside, with a gas inlet and outlet on the opposite side of the block from the compression chamber (Japanese Patent Laid-Open No. 2006-52709, hereinafter referred to as Patent Document 1).

[0003] As in Patent Document 1, forming a fluid flow path inside the block may accelerate deterioration of the block due to contact with the fluid. In particular, when the fluid is hydrogen, hydrogen embrittlement must be taken into consideration. To address hydrogen embrittlement, heat-resistant steel such as SUH660 is suitable for use as the block material. However, such heat-resistant steel is expensive and difficult to process, which increases the cost of the compressor.

[0004] The surface of the block that comes into contact with the fluid is exposed to high pressure. If there is a location on the contact surface where stress is likely to concentrate, there is a risk that the block will be damaged from that location. An object of the present invention is to provide a compressor that can reduce costs while suppressing deterioration, even when deterioration due to contact with the fluid is a concern.

[0005] A first aspect of the present invention is a compressor comprising: a cylinder having a cylinder chamber; a piston that reciprocates inside the cylinder; a head cover that closes one end face of the cylinder; a head cover retainer that is arranged on the opposite side of the cylinder with the head cover as a reference; and a fastener that connects the head cover retainer to the cylinder and urges the head cover retainer and the head cover toward the cylinder.

[0006] The cylinder chamber is a space where the fluid is compressed. The center portion of the head cover may be configured to fit inside the cylinder. The piston may be driven by any method, such as a hydraulic cylinder or an electric motor.

[0007] The head cover retainer does not have to contact the cylinder. The head cover retainer and the head cover may be adjacent to each other. Some kind of intervening object may be sandwiched between the head cover retainer and the head cover.

[0008] The fastener is connected to the head cover retainer and biases the head cover retainer toward the cylinder. The head cover is pressed against the head cover retainer and tightly contacts the cylinder. The fastener is, for example, a tie rod. The end of the tie rod is inserted into the head cover retainer.

[0009] The flow passages in the head cover are holes that connect the cylinder chamber and the external space. One end of the flow passage opens into the cylinder chamber. The other end of the flow passage opens into the side of the head cover, etc. The flow passages can be arranged in any manner. The number of flow passages is also arbitrary. Each flow passage may be simply linear, or may be bent along the way.

[0010] The recess is a depression created by cutting away a portion of the surface that opens to the cylinder chamber near the center. The recess reduces the difference in thickness between the center and outer edge of the head cover. Therefore, even during sudden temperature changes, the temperature difference between the center and outer edge of the head cover is reduced, allowing expansion and contraction to proceed smoothly. In addition, by opening one end of the flow path to the recess, the flow path can be shortened.

[0011] The convex portion is provided on the tip surface of the piston. When the piston approaches the head cover, the convex portion fits into the concave portion. This reduces the minimum volume of the cylinder chamber and promotes high pressure of the fluid. The concave and convex portions are shaped so as not to interfere with the movement of the piston.

[0012] A fillet is a chamfer provided at the corner between the inner circumferential surface and the bottom surface of a recess. The fillet connects the inner circumferential surface and the bottom surface of the recess in an arc shape, eliminating sharp corners. The fillet alleviates stress concentration at the outer edge of the bottom surface of the recess when the fluid is compressed.

[0013] One end of the flow path may open to the surface of the fillet. By forming the flow path at a substantially right angle to the surface of the fillet, the flow path is inclined with respect to the direction of movement of the piston. In this case, the flow path may be bent midway, and the other end of the flow path may open to the side surface of the head cover.

[0014] The connection port is provided at a position where the flow path opens to the external space. A check valve or the like is incorporated into the connection port. The exhaust hole is formed inside the head cover. One end of the exhaust hole opens to the inner peripheral surface of the connection port. The other end of the exhaust hole opens to the contact surface with the head cover retainer. A relief groove is formed in the contact surface with the head cover of the head cover retainer. The relief groove is positioned according to the exhaust hole. The relief groove prevents the exhaust hole from being blocked.

[0015] According to the compressor of the present invention, even in cases where deterioration due to fluid is a concern, it is possible to reduce costs while suppressing deterioration.

[0016] 1 is a perspective view of a compressor according to a first embodiment; FIG. 2 is a longitudinal sectional view of a compressor according to a second embodiment; FIG. 3 is an assembly diagram of a compressor according to a second embodiment;

[0017] 1 , a compressor 10 of this embodiment includes a drive unit 11, a drive rod 17, a base plate 13, a piston 27, a cylinder 21, a jacket 23, a head cover 41, a head cover retainer 61, a fastener 15, a joint 33, and a check valve 59. The drive unit 11 generates reciprocating motion of the piston 27. The drive unit 11 is powered by hydraulic pressure or the like. The piston 27 and the drive unit 11 are connected via a drive rod 17.

[0018] The cylinder 21 is cylindrical. The jacket 23 is cylindrical and surrounds the outside of the cylinder 21. The cylinder 21 and the jacket 23 are arranged concentrically. A gap is formed between the cylinder 21 and the jacket 23. The cylinder 21 and the jacket 23 are placed on the surface of the base plate 13.

[0019] The head cover 41 has a flange portion 43 and a fitting portion 45. The flange portion 43 closes the end faces of the cylinder 21 and the jacket 23. The flange portion 43 has a circular cross section with the same diameter as the jacket 23. The fitting portion 45 protrudes from one end face side of the flange portion 43. The fitting portion 45 is fitted into the inner circumferential surface of the cylinder 21. The space defined by the cylinder 21, the piston 27, and the head cover 41 is the cylinder chamber 31. The fluid to be compressed is, for example, hydrogen.

[0020] A seal 55 is disposed on the outer peripheral surface of the fitting portion 45. The seal 55 seals the gap between the cylinder 21 and the head cover 41. Coolant is supplied between the cylinder 21 and the jacket 23. The jacket 23 has a connection port 25. A fitting 33 is attached to the connection port 25. The fitting 33 serves as an inlet and an outlet for the coolant.

[0021] The fitting portion 45 has a recess 47 on its end surface. The recess 47 is recessed in a direction away from the piston 27. The recess 47 reduces the thickness of the center of the head cover 41, thereby reducing the difference in thickness between the center and the outer edge of the head cover 41. If the head cover 41 is heated, the temperature difference between the center and the outer edge of the head cover 41 is reduced.

[0022] The head cover 41 has a flow path 51. One end of the flow path 51 opens to the bottom surface of the recess 47. The other end of the flow path 51 opens to a side surface of the flange portion 43. The flange portion 43 has a connection port 53 on its side surface. A check valve 59, for example, is attached to the connection port 53. By opening one end of the flow path 51 to the bottom surface of the recess 47, the flow path 51 is shortened. This reduces the effect of the flow path 51 being exposed to high pressure.

[0023] A seal 28 is disposed on the outer peripheral surface of the piston 27. The seal 28 is in close contact with the inner peripheral surface of the cylinder 21. The piston 27 has a protrusion 29 on its tip surface. When the piston 27 comes closest to the head cover 41, the protrusion 29 fits into the recess 47, minimizing the volume of the cylinder chamber 31.

[0024] The head cover retainer 61 is disposed on the opposite side of the cylinder 21 with respect to the head cover 41. The head cover retainer 61 has the same shape as the base plate 13. The head cover retainer 61 comes into contact with the head cover 41 and covers the head cover 41. The outer edge of the head cover retainer 61 protrudes from the head cover 41.

[0025] The fastener 15 is disposed so as to surround the outside of the jacket 23. The fastener 15 extends in the axial direction of the cylinder 21. One end of the fastener 15 is integrated with the base plate 13. The other end of the fastener 15 is inserted into a fixing hole 63 of the head cover retainer 61. By screwing a nut 16 onto the fastener 15 protruding from the fixing hole 63, the head cover retainer 61 is urged toward the cylinder 21. At the same time, the head cover 41 is urged toward the cylinder 21. This seals the cylinder chamber 31. The fastener 15 is, for example, a tie rod.

[0026] The head cover retainer 61 does not come into contact with the fluid being compressed. Therefore, deterioration caused by the fluid is suppressed. The head cover retainer 61 does not need to be made of an expensive material. The head cover 41 does not need to be connected to the fastener 15. Therefore, the head cover 41 can be made smaller. Even if an expensive steel material such as SUH660 is used for the head cover 41, reducing the size of the head cover 41 allows for cost reduction.

[0027] An exhaust hole 57 opens in the connection port 53 at the end of the flow path 51. The exhaust hole 57 extends toward the head cover retainer 61. The head cover retainer 61 has an escape groove 67. The escape groove 67 is arranged on the contact surface with the head cover 41 and communicates with the exhaust hole 57. The exhaust hole 57 opens to the outside via the escape groove 67.

[0028] Figure 2 shows details of the head cover 41 of Figure 1. In Figure 2, the head cover 41 is turned upside down compared to Figure 1. The flange portion 43 has a larger diameter than the fitting portion 45. The fitting portion 45 fits into the inner circumferential surface of the cylinder 21. A recess 47 is hollowed out and opens at the end face of the fitting portion 45. The fitting portion 45 is cylindrical. A flow path 51 opens on the side surface of the flange portion 43. At this opening, the flange portion 43 has a connection port 53.

[0029] Figure 3 is a vertical cross-sectional view of the head cover 41 of Figure 2. The recess 47 is hollowed out from the end face of the fitting portion 45 toward the flange portion 43. The corner between the bottom surface of the recess 47 and the inner circumferential surface of the recess 47 is smoothly connected via an arc-shaped fillet 49. The fillet 49 alleviates stress concentration even when the cylinder chamber 31 becomes highly pressurized.

[0030] Two flow paths 51 are arranged opposite each other across the center of the head cover 41. One end of each flow path 51 opens into the fillet 49. The flow paths 51 are formed at approximately right angles to the surface of the fillet 49. Each flow path 51 is bent midway and opens into the side surface of the flange portion 43. An exhaust hole 57 opens into the inner peripheral surface of the connection port 53.

[0031] By forming the flow passage 51 from the surface of the fillet 49, the flow passage 51 extends so as to form a large intersection angle with the moving direction of the piston 27. Therefore, even when the flow passage 51 is bent midway and extended toward the side surface of the flange portion 43, the intersection angle at the bending point is large. By making the intersection angle large in this way, stress concentration at the bending point of the flow passage 51 is alleviated even when the flow passage 51 is exposed to high pressure.

[0032] Figure 4 is an assembly diagram of Figure 1. The head cover retainer 61 is fixed to the base plate 13 via the fastener 15. The head cover retainer 61 comes into contact with the head cover 41. The head cover 41 is biased by the head cover retainer 61 to close the cylinder 21 and the jacket 23. The head cover 41 has a flow path 51 that serves as an intake path for the fluid to be compressed and a flow path 51 that serves as a discharge path for the compressed fluid.

[0033] One end of each flow path 51 opens to the cylinder chamber 31. A check valve 59 is attached to the other end of each flow path 51. If fluid leaks around the check valve 59, the fluid is discharged to the outside through the exhaust hole 57 and the relief groove 67. This prevents damage to the check valve 59.

[0034] A gap is formed between the cylinder 21 and the jacket 23. Coolant is supplied to this gap to cool the area around the cylinder chamber 31. A joint 33 is attached to the jacket 23. The joint 33 serves as an inlet and outlet for the coolant. When the piston 27 approaches the head cover 41, the protrusion 29 of the piston 27 fits into the recess 47.

[0035] Second Embodiment As shown in Fig. 5 , a compressor 110 of this embodiment has a shortened flow path 51 in a head cover 141. The flow path 51 may extend in the direction of movement of the piston 27. The flow path 51 is the shortest path that penetrates the flange portion 43. One end of the flow path 51 opens to the fillet 49. The other end of the flow path 51 has a connection port 53.

[0036] The head cover retainer 161 comes into contact with the head cover 141. To prevent the head cover retainer 161 from blocking the flow path 51, the head cover retainer 161 has a piping hole 65.

[0037] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention, and all technical matters included in the technical ideas described in the claims are the subject of the present invention. The above-described embodiments are preferred examples, but a person skilled in the art can realize various alternatives, modifications, variations, or improvements from the contents of the disclosure of this specification, and these are included in the technical scope described in the appended claims.

[0038] REFERENCE SIGNS LIST 10, 110 Compressor 11 Drive unit 13 Base plate 15 Fastening device 16 Nut 17 Drive rod 21 Cylinder 23 Jacket 25 Connection port 27 Piston 28 Seal 29 Convex portion 31 Cylinder chamber 33 Joint 41, 141 Head cover 43 Flange portion 45 Fitting portion 47 Concave portion 49 Fillet 51 Flow path 53 Connection port 55 Seal 57 Exhaust hole 59 Check valve 61, 161 Head cover retainer 63 Fixing hole 65 Piping hole 67 Relief groove

Claims

1. A compressor comprising: a cylinder having a cylinder chamber; a piston that reciprocates inside the cylinder; a head cover that closes one end face of the cylinder; a head cover retainer that is positioned on the opposite side of the cylinder with the head cover as the reference; and a fastener that connects the head cover retainer to the cylinder and urges the head cover retainer and the head cover toward the cylinder.

2. The compressor according to claim 1, wherein the head cover has a flow path that serves as an intake path or a discharge path for the fluid compressed in the cylinder chamber.

3. The compressor according to claim 1 or 2, wherein the head cover has a recess on the surface that opens into the cylinder chamber, the recess being recessed in a direction away from the piston.

4. The compressor according to claim 3, wherein the piston has a protrusion that fits into the recess.

5. The compressor according to claim 3 or 4, wherein the recess has a fillet on the outer edge of the bottom surface.

6. The compressor according to claim 5, wherein one end of the flow path opens into the surface of the fillet.

7. A compressor as set forth in any one of claims 2 to 6, wherein the flow path has a connection port at an end remote from the cylinder chamber, the head cover has an exhaust hole extending from the inner circumferential surface of the connection port towards the head cover retainer, and the head cover retainer has an escape groove that connects the exhaust hole to the outside.

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