JP2009062871A - Reciprocating compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plunger type reciprocating compressor capable of preventing leakage of compressed gas outward with a simple constitution. <P>SOLUTION: This plunger type reciprocating compressor is provided for compressing gas in a compression space formed between a plunger 104 and a cylinder 101 by reciprocating motion of the plunger, and has a plurality of rod packings arranged in the plunger axis direction so as to slide by being brought into close contact with an outer peripheral surface of the plunger for preventing leakage of the gas compressed in the compression space from an outer peripheral part of the plunger, and a plurality of packing cases for storing the respective rod packings. Annular packing elastically contacting with the rod packing is incorporated into a storage surface of the rod packing inside of the packing cases. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reciprocating compressor that handles flammable gas and the like, and particularly relates to a reciprocating compressor that is suitable at an ultrahigh pressure of 30 MPa or more.

  An example of a conventional plunger type reciprocating compressor is described in Japanese Patent Application Laid-Open No. 2004-116330. In the compressor described in this publication, the working gas in the compression chamber formed between the plunger and the cylinder is compressed by the reciprocating motion of the plunger. In order to prevent the gas compressed in the compression chamber from leaking from the outer peripheral portion of the plunger, a plurality of circular rod packing seals that slide in close contact with the outer peripheral surface of the plunger are stacked in the axial direction of the plunger.

  A general example of the rod packing seal structure of the conventional reciprocating compressor is shown in FIG. In FIG. 5, the rod packing is closely attached to the rod 4 so that the left side 4 of the rod (plunger) 1 is the cylinder side and the gas compressed in the compression chamber does not leak to the low pressure side 5. In one set of rod packings, a low-pressure side packing 2b and a high-pressure side packing 2a are paired, which are mounted in each packing case 3, and a plurality of cases are mounted in the axial direction of the rod.

  The low-pressure side packing 2b is generally called a tangential cut packing, and is composed of three ring pieces having a tangential dividing surface within a cross section perpendicular to the axis. The high-pressure side packing 2a is generally called a radial cut packing, and is composed of three ring pieces having a dividing surface in the radial direction within a right angle. The purpose of forming the ring with three split rings is to allow the inner circumferential surface of the packing to follow the rod surface even when the inner surface of the packing is worn by sliding during operation. Accordingly, the shape and dimensions are taken into consideration so that a gap is formed in the circumferentially divided surface at the initial operation for both the low pressure side packing and the high pressure side packing.

  The leakage path of the compressed gas may be a sliding surface between the inner periphery of the packing and the outer periphery of the rod, and a contact surface between the low pressure side rod packing and the packing case. In order not to form the latter leakage flow path, the inner tangential packing is arranged in the passage leading from the outer periphery to the inner periphery of the low pressure side rod packing. And it arrange | positions so that radial packing may not overlap with its own opening gap so that the inner peripheral part opening gap of a tangential packing may be plugged up. For this reason, a method for constraining the relative position in the circumferential direction is required. Generally, the low-pressure tangential cut packing forms pins and pin holes on the relative surfaces of each other to fix the circumferential position.

JP 2004-116330 A

  The conventional reciprocating compressor described in Patent Document 1 and FIG. 5 uses a technique in which a plurality of metal or resin rod packings are arranged between a cylinder and a plunger to minimize compressed gas leakage. .

  By the way, there is generally an appropriate tolerance between the rod packing and the plunger, and there is a system that lubricates depending on the compressor application to create an oil film and suppress leak gas, and a seal that allows some leakage in a completely dry state Although there is a method, this compressor uses a seal method by lubrication that minimizes leakage from the gap between the plunger and rod packing, but this seal method also causes gas to break down to the low pressure side due to the destruction of the oil film. The amount of leaked gas does not become zero.

  The path of leakage gas from the rod packing is roughly divided into two systems between the rod packing inner peripheral surface and the plunger outer peripheral surface, and between the rod packing back surface and the packing case contact surface. Leakage in the former system occurs at a portion where the rod packing floats in contact with the movement of the plunger as it moves up or down, or does not conform to the shape mismatch or floating. On the other hand, the leakage of the latter system is caused by friction when the sliding direction changes by 180 ° at the top dead center and bottom dead center of the plunger, and the left and right side surfaces and the back surface of the rod packing are separated from the contact surface of the packing case. It happens when you can. Past experience has shown that the leakage from the contact surface due to friction is relatively high in compressors with low plunger vertical motion (short pitch). If the compressed gas is not discharged but leaks, it leads to low efficiency of the compressor, resulting in an economical burden on the user side of the compressor.

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a plunger-type reciprocating compressor that can prevent leakage of compressed gas to the outside with a simple configuration.

  The present invention for achieving the above-mentioned object is a plunger-type reciprocating compressor that compresses a gas in a compression chamber formed between a plunger and a cylinder by a reciprocating motion of the plunger, and the gas compressed in the compression chamber is the plunger A plurality of rod packings arranged in the plunger axial direction so as to slide in close contact with the outer peripheral surface of the plunger so as to prevent leakage from the outer peripheral portion of the plunger, and a plurality of packing cases for storing each rod packing, An annular packing that elastically contacts the rod packing is incorporated in a storage surface of the rod packing inside the packing case.

  In addition, a chamber is installed between a plurality of packing cases, a gap between the packing case and the outer peripheral surface of the plunger is connected to the chamber, and leakage gas is guided to the chamber to expand the volume. You may do it.

  The annular packing may be incorporated in the rod packing so as to be elastically contacted in the movement direction of the plunger.

  According to the present invention, since the amount of leaked gas can be reduced, the compression efficiency can be greatly increased, and the running cost can be reduced, so that the reliability can be increased.

An embodiment of a reciprocating compressor according to the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a cylinder in which a rod packing of a plunger type reciprocating compressor is arranged. The plunger-type reciprocating compressor pressurizes hydrogen used in the fuel cell, and the pressure reaches 70 Mpa. Therefore, a leak prevention device is provided for sealing high-pressure gas and preventing leakage to the outside of the compressor.

  As the rod-shaped plunger 104 moves in the axial direction in the cylinder ring 102 forming the compression chamber 100, the working gas is compressed in the compression chamber 100 located at the tip of the plunger 104. The plunger 104 receives a reciprocating force from the right end of FIG. 1 via a crankshaft connected to a drive source (not shown), a connecting rod connected to the crankshaft, and an intermediate rod connected to the connecting rod. Reportedly.

  A cylinder head 103 is attached to the end surface of the cylinder ring 102 so that the compression chamber 100 is formed at the left end of the plunger 104. A valve 107 connected to the compression chamber 100 is provided inside the cylinder head 103, and the valve 107 includes a hydrogen gas suction port 105 and a discharge port 106. By the movement of the plunger 104 in the right direction, hydrogen gas is sucked from the suction port 105 through the suction valve inside the valve 107 and guided to the compression chamber 100. As the plunger 104 moves leftward, the suctioned hydrogen gas is compressed in the compression chamber 100, and the compressed hydrogen gas is discharged from the discharge port 106 via the discharge valve inside the valve 107.

Next, the structure of the seal part of the cylinder 101 will be described.
The compressed hydrogen gas has an extremely high pressure and tends to flow from the gap between the sliding surface between the inner peripheral surface of the cylinder ring 102 and the outer peripheral surface of the plunger 104 to the frame side 201. Is arranged in the axial direction so as to be in pressure contact with the outer peripheral surface of the plunger 104, and the pressure is gradually reduced to prevent gas leakage. High pressure side packing cases 31 to 34 and low pressure side packing cases 35 to 38 for housing the rod packing are arranged in the cylinder 101.

  As shown in FIG. 4, a pin 31d and a pin hole 31c are disposed in the high pressure side packing case so that the cut surfaces of the scroll cut type rod packing 31a with oil groove and the scroll cut type rod packing 31b without oil groove do not overlap. They are arranged side by side by being restrained by fitting. The rod packing cases 32 to 34 have the same configuration. Further, the low pressure side rod packing cases 35 to 38 have the same configuration as that of the high pressure side packing cases 31 to 34 and a structure in which a backup ring 44 is further arranged behind.

  This will be described in detail with reference to FIG. FIG. 2 is an enlarged cross-sectional view of the low-pressure side packing case shown in FIG. In FIG. 2, packing cases 35 and 37 are arranged in the axial direction on the outer peripheral surface of the plunger 104, and a chamber case 36 is arranged therebetween. A hollow chamber 36 a is formed on the plunger 104 side of the chamber case 36. Since the lower ends of the packing cases 35 and 37 slide with the outer peripheral surface of the plunger 104, there are slight gaps 35a and 37a. These gaps communicate with the chamber 36a. The chamber 36a acts to guide the leaked gas through the gap 35a to expand the volume and reduce the pressure to guide the next rod packing.

  As described above, the rod packings 31a and 31b and the backup ring 44 are arranged in the packing cases 35 and 37 side by side. Then, annular storage grooves 39 and 40 are formed in the packing case so as to face the side surfaces of the backup ring 44, and annular packing (O-rings) 39a and 40a are stored in these grooves, respectively. The O-rings 39a and 40a maintain the airtightness by always elastically contacting the backup ring 44 in the movement direction of the plunger 104. Since the surface of the O-ring does not slide due to the movement of the plunger 104, there is no wear, so that the airtightness can be kept good for a long time.

  Next, the path of the leakage gas in the rod packing part and the correspondence at the O-ring in the embodiment of the present invention will be described. FIG. 3 is a cross-sectional view for explaining the path of leakage gas in the rod packing portion. FIG. 3 (1) shows the state of the plunger pushing process in which the plunger 104 has moved to the left, and FIG. The state of the plunger pulling process which moved to the right is shown.

  In the plunger pushing process of FIG. 3A, the rod packings 31a and 31b and the backup ring 44 (referred to as rod packing or the like) are moved to the left by the friction caused by the pushing movement of the plunger 104. A slight gap 35c is formed between the right side surface of the container and the storage surface inside the packing case 35. Further, a slight gap 35b is also formed between the back surface of the rod packing or the like and the storage surface inside the packing case 35. This is due to the fact that the rod packing or the like contracts inward due to elasticity, or the friction during the reciprocating motion of the plunger. This is caused by distortion of the rod packing or the like.

  In the plunger pulling step shown in FIG. 3 (2), the entire rod packing and the like are moved to the right by the friction caused by the pulling movement of the plunger 104, and slightly on the left side surface of the rod packing 31a and the storage surface inside the packing case 35. A gap 35d is generated.

  In the above situation, when the plunger 104 reciprocates, the operations of (1) and (2) in FIG. 3 are repeated, and the compressed gas sequentially flows through the gas leakage flow path including the gaps 35a, 35b, and 35c. Thus, it gradually leaks every time it reciprocates. This gas leakage flow path is the same for the packing case 37.

  In the present embodiment, as shown in FIG. 2, a backup ring 44 is installed behind the rod packing 31b, an O-ring is provided behind the rod packing 31b, and elastic contact is made with the backup ring 44. Since the gap 35c shown in FIG. 5 is sealed (closed), the gas leakage channel can be eliminated. The same applies to the packing case 37. Accordingly, gas leakage can be prevented even when the plunger 104 reciprocates.

  Further, by installing the chamber 36 between the packing cases 35 and 37, the leakage gas is expanded to reduce the pressure and then guided to the next rod packing, so that the leakage gas sealing effect is further improved. It can be made. Since the surface of the O-ring does not slide due to the movement of the plunger 104, there is no wear, so that the airtightness can be kept good for a long time.

It is a longitudinal cross-sectional view of the cylinder which has arrange | positioned the rod packing of the reciprocating compressor of this invention Example. It is an expanded sectional view of the packing case part of the embodiment of the present invention. It is sectional drawing explaining the path | route of the leaking gas in the rod packing part of this invention Example. It is a top view of the rod packing of the Example of this invention. It is explanatory drawing of the rod packing seal structure of the conventional reciprocating compressor.

Explanation of symbols

31-37 ... packing case, 31a, 31b ... rod packing, 36 ... chamber, 39, 40 ... annular groove, 39a, 40a ... annular packing (O-ring), 44 ... backup ring, 100 ... compression chamber, 101 ... cylinder, 102 ... Cylinder ring, 103 ... Cylinder head, 104 ... Plunger.

Claims (3)

In a plunger-type reciprocating compressor that compresses gas in a compression chamber formed between a plunger and a cylinder by reciprocating movement of the plunger,
A plurality of rod packings provided in the plunger axial direction so as to slide in close contact with the outer peripheral surface of the plunger so as to prevent the gas compressed in the compression chamber from leaking from the outer peripheral portion of the plunger, and each rod A reciprocating compressor comprising a plurality of packing cases for storing packings, and an annular packing that is in elastic contact with the rod packing is built in a storage surface of the rod packing inside the packing case.   The reciprocating compressor according to claim 1, wherein a chamber is installed between a plurality of packing cases, a gap between the packing case and the outer peripheral surface of the plunger is communicated with the chamber, and leakage gas is passed to the chamber. A reciprocating compressor characterized in that it is configured to guide and expand its volume.   3. The reciprocating compressor according to claim 1, wherein the annular packing is built in the rod packing so as to elastically contact the rod packing in a movement direction of the plunger.

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