JP2008180090A - Compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To impart sufficient follow-up capability to swing generated with slide to slide members located on a border between regions having pressure values different from each other, and thereby to enhance sealing performance in the regions, in a compressor. <P>SOLUTION: A polytetrafluoroethylene composition containing crosslinked polytetrafluoroethylene is used for at least one of the slide members arranged between the regions having pressure values different from each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a compressor used in a vehicle air conditioner or the like.

  In consideration of the influence on the environment, development of an air conditioning apparatus using carbon dioxide gas as a refrigerant gas is proceeding. Generally, in this type of air conditioner, it is necessary to compress the carbon dioxide gas at a pressure higher than the pressure when compressing the refrigerant gas with a conventional air conditioner using a refrigerant gas.

  The compressor has a mechanism in which a metal member and a non-metal member slide, and among these mechanisms, there is a mechanism in which the gas pressure is different across the sliding mechanism. Examples of this type of mechanism include cylinders and piston rings, rotating shafts and lip ring type seals. In this type of mechanism, since both members slide, it is particularly required that the frictional resistance between both members be low. In addition, from the viewpoint of durability, high wear resistance is particularly required for non-metallic members. Furthermore, since there is a pressure difference across the sliding mechanism, high sealing performance is required for the sliding portion.

  In a conventional compressor that compresses refrigerant gas, for example, polytetrafluoroethylene (PTFE) is used as a non-metallic member. However, PTFE does not have sufficient spring elasticity. For this reason, when PTFE is used for the sliding member of the compressor, when a swing such as a shaft swing occurs between the members, a gap is generated between the members because PTFE cannot sufficiently follow the swing, As a result, gas leakage may occur between members. This gas leakage is particularly problematic in a compressor using carbon dioxide gas as the refrigerant gas because the gas needs to be compressed at a high pressure.

  Patent Document 1 is a conventional document disclosing a piston ring made of PTFE-containing material. Further, Patent Document 2 is a conventional document disclosing a lip ring made of PTFE-containing material.

JP 2006-283634 JP 2004-44745 A

  The present invention has been made in view of such a situation, and a problem to be solved by the present invention is to swing the sliding member on the boundary of the region where the pressures are different from each other. It is to provide a technique for providing sufficient followability, thereby improving the sealing performance of the region.

  In order to solve the above-described problems, the present invention provides the following compressor. That is, the present invention relates to a polytetrafluoroethylene composition (PTFE composition) in which at least one sliding member provided between regions having different pressures in the compressor includes crosslinked polytetrafluoroethylene (crosslinked PTFE). Is provided. The compressor characterized by comprising. The other sliding member that is in sliding contact with the sliding member made of the PTFE composition containing cross-linked PTFE is made of, for example, metal.

  A sliding member made of a PTFE composition containing cross-linked PTFE includes, for example, a lip ring that slides with respect to a rotating shaft. In this case, the rotating shaft passes from one of the two regions having different pressures to the other, and the lip ring prevents gas from leaking from the high pressure region to the low pressure region along the rotating shaft. Since the PTFE composition containing cross-linked PTFE has spring elasticity, it has a high followability with respect to the oscillation of the rotating shaft.

  Another example of a sliding member made of a PTFE composition containing crosslinked PTFE is a piston ring that slides relative to a cylinder. In this case, the cylinder bore is a high pressure region, and the space between the cylinder inner wall and the piston is a low pressure region.

  The PTFE composition containing crosslinked PTFE may further contain a solid lubricant. Examples of solid lubricants include graphite and molybdenum disulfide.

  The PTFE composition containing crosslinked PTFE may further contain an antiwear additive. Examples of antiwear additives include spherical carbon, carbon fibers, metal oxides, and ceramics.

  The PTFE composition containing crosslinked PTFE may further contain a friction modifier. Examples of friction modifiers include metal sulfides, lead and zinc.

  A PTFE composition comprising crosslinked PTFE has spring elasticity, a low coefficient of friction, and high wear resistance. For this reason, the sliding member which consists of a PTFE composition containing crosslinked PTFE has high followability to swinging, little friction during sliding, and long life. Therefore, according to the compressor of the present invention, it is possible to prevent an air gap from being generated between the sliding members due to the swinging associated with the sliding, and gas leakage between the regions having a pressure difference. Moreover, the sealing performance between the regions having a pressure difference can be maintained in a good state for a long period while suppressing energy loss during sliding. These effects can be compatible.

  The present invention is characterized in that, in a sliding mechanism of a compressor, a polytetrafluoroethylene (PTFE) composition containing crosslinked polytetrafluoroethylene (PTFE) is used as at least one of members sliding with each other. .

  A PTFE composition containing cross-linked PTFE has a low coefficient of friction substantially equal to that of conventionally used PTFE, and is excellent in wear resistance as compared with conventional PTFE. Furthermore, PTFE compositions containing cross-linked PTFE have spring elasticity not found in conventional PTFE. For this reason, it is possible to follow the movement of the shaft and other movements, and as a result, it is possible to improve the sealing performance between the sliding members.

  Thereby, in this invention, it is possible to provide simultaneously the low frictional resistance equivalent to PTFE, the abrasion resistance higher than PTFE, and the high followability resulting from high elasticity, and as a result, especially high pressure Even a compressor that compresses gas can maintain high sealing performance over a long period of time while suppressing loss due to frictional resistance.

  As an example of a sliding member to which the present invention can be applied, a shaft seal device 100 and a piston part 200 of a swash plate compressor shown in FIG. 1 will be described below.

  A shaft seal device 100 that is Embodiment 1 of the present invention will be described. Referring to FIG. 2, the shaft seal device 100 includes a housing 1, a first seal member 2 disposed on the high pressure side, and a second seal member 3 disposed on the low pressure side. The shaft seal device 100 rotates the penetrating rotary shaft 4. Then, sliding occurs between the first seal member 2 and the rotating shaft 4 and between the second seal member 3 and the rotating shaft 4. During the operation of the compressor, in the figure, the left side of the housing 1 is the low pressure side region, and the right side is the high pressure side region.

  The housing 1 has a circular hole, and the first seal member 2 is held by the inner wall surface of the circular hole. The first seal member 2 is a rubber lip ring, and holds the second seal member 3 having a substantially L-shaped cross section in the drawing. The first seal member 2 is covered on the right side in the drawing, that is, in the high pressure side region so as to cover between the second seal member 3 and the rotary shaft 4, and its end portion is in contact with the rotary shaft 4. ing. The second seal member 3 is made of a PTFE composition containing cross-linked PTFE, and has a spirally concave groove on the sliding surface with the rotating shaft 4. A pumping effect is generated by this spiral groove, and a good sealing function is realized between the rotating shaft 4 and the rotating groove 4.

  In addition, it is preferable that the PTFE composition which comprises the 2nd sealing member 3 contains fillers, such as a solid lubricant, an abrasion resistance additive, a friction modifier, in addition to bridge | crosslinking PTFE. Examples of solid lubricants include graphite and molybdenum disulfide. Examples of antiwear additives include spherical carbon, carbon fibers, metal oxides, and ceramics. Examples of friction modifiers include metal sulfides, lead and zinc.

  According to the shaft seal device 100, the second seal member 3 is made of a PTFE composition containing cross-linked PTFE, and has spring elasticity not found in conventional PTFE, so has high followability to the shaft runout of the rotating shaft 4, As a result, it becomes possible to improve the sealing performance during the operation of the compressor. Moreover, since the 2nd sealing member 3 consists of a PTFE composition containing bridge | crosslinking PTFE and has higher abrasion resistance, the pump effect can be maintained for a long period of time. For this reason, it becomes possible to maintain the sealing performance by a pump effect for a long period of time. These effects can be realized while maintaining a low frictional resistance equivalent to that of the conventional PTFE second seal member.

  A piston portion 200 that is Embodiment 2 of the present invention will be described with reference to FIG. The piston part 200 is an enlarged view centering on one of the cylinder heads in the cross-sectional view of the swash plate compressor shown in FIG. 1. The piston part 200 includes a cylinder block 21, a cylinder head 22, a valve plate 23 and a piston 24. The cylinder head 22 has a suction chamber 25 and a discharge chamber 26, and the valve plate 23 has a suction hole 27 and a discharge hole 28 corresponding to these. In the piston portion 200, the high pressure side region corresponds to the cylinder bore 31, and the low pressure side region corresponds to the space on the left side of the piston ring 30 in the drawing in the space between the cylinder block 21 and the piston 24.

  Referring to FIG. 4 in which a region A surrounded by a dotted line in FIG. 3 is enlarged, the piston 24 has a groove 29 along the outer peripheral surface in the vicinity of the top dead center side end, and the piston ring 30 is fitted in the groove 29. Are combined.

  As shown in FIG. 5, the piston ring 30 has a conical ring shape whose outer diameter is larger than that of the piston 24, and is made of a PTFE composition containing cross-linked PTFE. The piston ring 30 reciprocates while being in contact with the inner wall of the cylinder block 21, and sliding occurs between them.

  In addition, it is preferable that the PTFE composition which comprises the piston ring 30 contains fillers, such as a solid lubricant, an abrasion resistance additive, a friction modifier, in addition to bridge | crosslinking PTFE. Examples of solid lubricants include graphite and molybdenum disulfide. Examples of antiwear additives include spherical carbon, carbon fibers, metal oxides, and ceramics. Examples of friction modifiers include metal sulfides, lead and zinc.

  According to the piston part 200, the piston ring 30 is made of a PTFE composition containing cross-linked PTFE. Therefore, the piston part 30 has spring elasticity not found in a conventional piston ring made of PTFE, and has high followability to the axial vibration of the piston 24. At the same time, since it has higher wear resistance than a conventional piston ring made of PTFE, wear is less and the effect of sealing blow-by gas can be maintained for a long time. Therefore, high sealing performance can be stably maintained for a long time. At the same time, since the frictional resistance is low as in the conventional PTFE, the energy loss due to friction accompanying the reciprocating motion of the piston can be suppressed to the same level as in the conventional case.

  As mentioned above, although this invention was demonstrated according to embodiment and an Example, this invention is not limited to this, It cannot be overemphasized that various deformation | transformation are possible within the scope of the present invention. .

It is a schematic cross section of the swash plate type compressor which is one embodiment of this invention. It is a schematic cross section for demonstrating the shaft seal apparatus 100 which is Example 1 of this invention. It is a schematic cross section for demonstrating the piston part 200 which is Example 2 of this invention. FIG. 4 is an enlarged view of a portion A surrounded by a dotted line in FIG. 3. 3 is a schematic cross-sectional view for explaining a piston ring 30. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 2 1st sealing member 3 2nd sealing member 4 Rotating shaft 21 Cylinder block 22 Cylinder head 23 Valve plate 24 Piston 25 Suction chamber 26 Discharge chamber 27 Suction hole 28 Discharge hole 29 Groove 30 Piston ring

Claims (9)

  In the compressor, at least one of the sliding members provided between regions having different pressures is made of a polytetrafluoroethylene composition containing crosslinked polytetrafluoroethylene.   2. The compressor according to claim 1, wherein the sliding member made of the polytetrafluoroethylene composition containing the crosslinked polytetrafluoroethylene is a lip ring that slides with respect to the rotating shaft. .   2. The compressor according to claim 1, wherein the sliding member made of the polytetrafluoroethylene composition containing the crosslinked polytetrafluoroethylene is a piston ring that slides with respect to the cylinder.   The compressor according to claim 1, wherein the polytetrafluoroethylene composition containing the crosslinked polytetrafluoroethylene further contains a solid lubricant.   The compressor according to claim 4, wherein the solid lubricant includes at least one of graphite and molybdenum disulfide.   The compressor according to claim 1, wherein the polytetrafluoroethylene composition containing the crosslinked polytetrafluoroethylene further contains an antiwear additive.   7. The compressor according to claim 6, wherein the anti-wear additive includes at least one of spherical carbon, carbon fiber, metal oxide, and ceramics.   The compressor according to claim 1, wherein the polytetrafluoroethylene composition containing the crosslinked polytetrafluoroethylene further contains a friction modifier.   The compressor according to claim 8, wherein the friction modifier includes at least one of metal sulfide, lead, and zinc.

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