JP2009281232A - Piston ring for piston reciprocating type compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston ring for a piston reciprocating type compressor capable of automatically showing excellent sealing performance in any of compression stroke and suction stroke. <P>SOLUTION: The annular piston ring is installed in a groove on a piston outer circumference surface and is slidably pressed on a cylinder bore inner circumference surface. A section shape of the piston ring includes a part having a shape in which angle D1 of a surface forming a part of the piston ring at high pressure fluid existing side in a cylinder to an cylinder bore inner circumference surface and angle D2 of a piston ring surface at a low pressure fluid existing side positioned at an opposite side of the high pressure fluid existing side with a part of the piston ring put therebetween to the cylinder bore inner circumference surface satisfy a relation D1>D2, in both of compression stroke and suction stroke. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a piston ring of a piston reciprocating compressor, and more particularly, to a piston reciprocating compressor capable of exhibiting good sealing performance with a cylinder bore inner peripheral surface in both a compression stroke and a suction stroke. It relates to the piston ring.

  In a piston reciprocating compressor, an annular groove is usually formed on the outer peripheral surface of a piston that is reciprocated in a cylinder, and an annular piston ring that is slidably pressed against the inner peripheral surface of the cylinder bore is formed in the groove. It is installed. This piston ring provides a seal between the high-pressure side and the low-pressure side of the piston that is reciprocated in the cylinder. For example, in order to improve the volume efficiency of the compressor, the leakage of high-pressure gas to the outside of the cylinder is reduced. The In addition, the compressed fluid (for example, refrigerant gas) often contains lubricating oil to lubricate the compressor itself and each part in the system in which the compressor is incorporated. By improving the sealing performance of the compressor, for example, an appropriate amount of lubricating oil in the crank chamber of a compressor having a lubricating part can be secured, and the amount of lubricating oil flowing out from the compressor (so-called OCR (Oil Circulation Ratio)) can be reduced. Or

In order to improve the sealing performance of the piston ring, for example, Patent Document 1 shows that an annular seal ring is attached to the groove on the outer peripheral surface of the piston and the seal ring protrudes when pressure is applied. No specific protrusion mechanism is shown. Further, Patent Document 2 describes a combination ring made up of a pair of outer ring and inner ring, but there are problems such as a large number of parts and low mountability.
JP-A-10-153170 JP 2000-352464 A

  A general structure of a piston ring composed of a single seal ring is, for example, as shown in FIG. In FIG. 4, reference numeral 101 denotes a piston that is reciprocally inserted into the cylinder 102. An annular piston ring 104 is mounted in an annular groove 103 formed on the outer peripheral surface of the piston 101. Sealing with the inner peripheral surface of the cylinder bore 105 is performed. Reference numeral 106 denotes a cylinder block, 107 denotes a valve plate in which a suction hole 108 and a discharge hole 109 are formed. The valve plate is sucked into the cylinder 102 through the suction hole 108 from the suction chamber 111 formed in the cylinder head 110. A fluid (for example, a refrigerant gas) is compressed as the piston 101 reciprocates, and the compressed fluid is discharged from the cylinder 102 into the discharge chamber 112 through the discharge hole 109.

  However, the above structure has the following problems. 4 is schematically shown in FIG. 5, the pressure acting on the piston ring 104 varies as shown in FIG. 6 between the compression stroke and the suction stroke. That is, in the intake stroke, the piston ring 104 is applied with a low-pressure side cylinder pressure Pcyl (= suction pressure Ps) on one side, and a high-pressure side crank chamber pressure Pc is applied on the other side. This is the state. At this time, an angle D1 formed by a surface forming a part of the piston ring 104 on the high pressure fluid existence side in the cylinder 102 with respect to the inner peripheral surface of the cylinder bore 105 is different from the high pressure fluid existence side between the piston ring 104 and the cylinder ring 105. Since the piston ring surface located on the opposite side on the low pressure fluid existence side is larger than the angle D2 formed with respect to the inner peripheral surface of the cylinder bore 105 (that is, because D1> D2), the piston ring 104 is provided with the piston ring 104. Fluid pressure acts in the direction of pressing toward the inner peripheral surface of the cylinder bore 105, and the high and low pressure sides on both sides of the piston ring 104 are well sealed.

  However, in the compression stroke, the surface side of the piston ring 104 having a small angle with respect to the inner peripheral surface of the cylinder bore 105 is the high pressure fluid existence side (the existence side of the fluid compressed in the cylinder 102: the high pressure side cylinder pressure Pcyl). The crank chamber pressure Pc on the low pressure side is applied to the surface side having a large angle with respect to the inner peripheral surface of the other cylinder bore 105, and this state is maintained up to the top dead center of the piston 101. Therefore, an angle D1 formed by a surface forming a part of the piston ring 104 on the high pressure fluid existence side in the cylinder 102 with respect to the inner peripheral surface of the cylinder bore 105 is opposite to the high pressure fluid existence side between the piston ring 104 and the piston ring 104. The relationship between the piston ring surface on the side of the low pressure fluid existing side and the angle D2 formed with respect to the inner peripheral surface of the cylinder bore 105 is opposite to the suction stroke, that is, D2> D1. Therefore, the fluid pressure in the direction in which the piston ring 104 is pressed toward the inner peripheral surface side of the cylinder bore 105, which has acted in the suction stroke, does not act, and the sealing performance of the piston ring 104 is reduced accordingly, and the high pressure side to the low pressure side. There is a risk that high pressure gas will leak. At the same time, the lubricating oil contained in the fluid cannot be properly sealed, so that it is not possible to secure an appropriate amount of lubricating oil in the crank chamber or increase the amount of lubricating oil flowing out (OCR) from the compressor. There is.

  Therefore, in view of the prior art as described above, the problem of the present invention is that in the case of either the compression stroke or the suction stroke, which consists of a single piston ring without causing an increase in the number of parts and causing no problem in the mounting property. Another object of the present invention is to provide a piston ring for a piston reciprocating compressor that can automatically exhibit excellent sealing performance.

  In order to solve the above problems, a piston ring of a piston reciprocating compressor according to the present invention is mounted in a groove formed in an outer peripheral surface of a piston reciprocated in a cylinder of the compressor, An annular piston ring that is slidably pressed against the surface, and the piston ring has a cross-sectional shape in which a part of the piston ring is located on the high pressure fluid presence side in the cylinder during both the compression stroke and the suction stroke. An angle D1 formed by the surface to be formed with respect to the inner peripheral surface of the cylinder bore, and a piston ring surface on the low pressure fluid existing side located on the opposite side of the high pressure fluid existing side with a part of the piston ring interposed therebetween The angle D2 formed with respect to is characterized by having a shape portion satisfying the relationship of D1> D2.

  In such a piston ring, a single piston ring has an angle D1 of the piston ring surface on the high-pressure fluid existing side> an angle D2 of the piston ring surface on the low-pressure fluid existing side for both the compression stroke and the intake stroke. Since it has a shape that satisfies the relationship, fluid pressure is applied in both the compression stroke and the suction stroke, that is, substantially over the entire range during piston reciprocation, in the direction that presses the piston ring toward the inner peripheral surface of the cylinder bore. This allows the piston ring to automatically exhibit excellent sealing performance at all times during piston operation. As a result, leakage of the high-pressure fluid from the high-pressure side to the low-pressure side can be suppressed, and the lubricating oil contained in the fluid can be properly sealed.

  In the piston ring of the piston reciprocating compressor according to the present invention, as the cross-sectional shape of the piston ring, for example, as shown in an embodiment described later, a U shape, a V shape, an X shape, a Y shape, Either a W shape or a combination of any of them can be employed. By adopting such a cross-sectional shape, the piston ring according to the present invention can be easily configured as a single ring structure instead of a combination ring.

  Further, in order to reduce the weight of the whole compressor, it is possible to adopt a form in which the cylinder is made of aluminum or an aluminum alloy.

  Further, the material of the piston ring itself is not particularly limited, but a material that can exhibit resistance to a fluid (for example, a refrigerant), for example, a property of low swelling, and high resistance to a lubricating oil or the like is preferable. As such a material, for example, at least one material selected from the group consisting of polytetrafluoroethylene, polyetheretherketone, polyphenyleneamide, and polyamideimide can be used. In particular, a material having a high temperature at which bending occurs due to an applied load and a high melting point is preferable depending on use conditions. From this aspect, a cross-linked product of the above materials is more preferable. By using such a material, stable performance can be maintained even at high operating temperatures, and when the cylinder is made of aluminum or an aluminum alloy, high wear resistance can be obtained for the cylinder. A low coefficient of friction can be realized.

  In addition, the fluid used in the piston reciprocating compressor in the present invention is not particularly limited, but particularly when the fluid used is a refrigerant, the present invention can exhibit excellent sealing performance.

  In addition, the present invention can be applied to piston reciprocating compressors for all uses, but it is required to have excellent sealing performance and high durability of the piston ring, especially when incorporated in a system and mass-produced. It is suitable for application to a compressor used in a vehicle air conditioner.

  As described above, according to the piston ring of the piston reciprocating compressor according to the present invention, a single piston ring configuration does not cause an increase in the number of parts, a problem of mounting property, and a large cost increase. In addition, in both the compression stroke and the suction stroke, the fluid pressure acting on the piston ring can be used to automatically exert an excellent sealing performance, suppressing the leakage of high pressure fluid from the high pressure side to the low pressure side. As a result, the volumetric efficiency of the compressor can be improved and the proper sealing performance can be demonstrated for the lubricating oil contained in the fluid. It is possible to reduce the amount of lubricating oil outflow (OCR).

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a piston ring of a piston reciprocating compressor for compressing a refrigerant gas incorporated in a vehicle air conditioner or the like according to an embodiment of the present invention, and corresponds to part A of FIG. Shows the part. In FIG. 1, reference numeral 1 denotes a piston of a piston reciprocating compressor, and the piston 1 is inserted into a cylinder 2 so as to freely reciprocate. An annular groove 3 is formed on the outer peripheral surface of the piston 1, and an annular piston ring 4 is mounted in the groove 3, so that an inner peripheral surface of the cylinder bore 5 formed in the cylinder block 6 is formed. Sealing between them is performed. In this embodiment, the cross-sectional shape of the piston ring 4 is U-shaped, and the tips of both U-shaped arms are arranged so as to be slidable on the inner peripheral surface of the cylinder bore 5, respectively. The part can be sealed between both sides of the arm.

  In the present embodiment, the cylinder 2 is made of aluminum or an aluminum alloy, and the overall weight of the compressor is reduced. As a material of the piston ring 4, polytetrafluoroethylene, polyetheretherketone, polyphenyleneamide can be used as a material having a high resistance to a refrigerant, a small swelling property, and a high resistance to a lubricating oil. At least one material selected from the group consisting of polyamideimides, in particular, a cross-linked product thereof is used. By constituting the piston ring 4 from such a material, high wear resistance and a low friction coefficient can be obtained for the cylinder 2 made of aluminum or an aluminum alloy.

  In the structure according to the embodiment as described above, a sealing action using the fluid pressure in the cylinder 2 as shown in FIG. 2 is automatically obtained. As shown in FIG. 2, in the compression stroke, one arm portion (piston head side arm portion) of the piston ring 4 having a U-shaped cross-sectional shape has a high-pressure fluid existing side (the fluid compressed in the cylinder 102). The angle D1 formed by the surface of the piston ring 4 on the existing side: the cylinder pressure Pcyl on the high pressure side with respect to the inner peripheral surface of the cylinder bore 5 is applied to the other side with the U-shaped arm portion in between. The surface of the piston ring 4 that is the surface of the cylinder is larger than the angle D2 formed with respect to the inner peripheral surface of the cylinder bore 5 (D1> D2), and this state is maintained until the top dead center of the piston 1. Due to the relationship of D1> D2, fluid pressure acts on the piston ring 4 in a direction in which the piston ring 4 is constantly pressed toward the inner peripheral surface of the cylinder bore 5 during the compression stroke, and the relationship of D1> D2 is maintained. The high and low pressure sides on both sides of the arm portion of the letter-shaped piston ring 4 are well sealed.

  In the intake stroke, as shown in FIG. 2, the high pressure fluid is on the crank chamber pressure Pc side, and the low pressure fluid is on the piston head side cylinder pressure Pcyl (= intake pressure Ps) side, contrary to the compression stroke. However, in the other arm portion (crank chamber side arm portion) of the piston ring 4 having a U-shaped cross-sectional shape, an angle D1 formed by the surface of the piston ring 4 on the high-pressure fluid existing side with respect to the inner peripheral surface of the cylinder bore 5 Is larger than the angle D2 formed by the surface of the piston ring 4 which is the other side of the cylinder pressure Pcyl on the low pressure side and the U-shaped arm portion with respect to the inner peripheral surface of the cylinder bore 5, and D1> D2 The relationship is established, and this state is maintained until the bottom dead center of the piston 1. Due to the relationship of D1> D2, fluid pressure acts on the piston ring 4 in a direction in which the piston ring 4 is constantly pressed toward the inner peripheral surface of the cylinder bore 5 during the intake stroke, and the relationship of D1> D2 is maintained. The high and low pressure sides on both sides of the arm portion of the letter-shaped piston ring 4 are well sealed.

  Thus, in both the compression stroke and the suction stroke, that is, substantially over the entire range during the reciprocating motion of the piston 1, the fluid pressure in the direction in which the piston ring 4 is pressed toward the inner peripheral surface of the cylinder bore 5 automatically acts. Thus, the piston ring 4 always exhibits excellent sealing performance while the piston 1 is in operation. As a result, leakage of the high pressure fluid from the high pressure side to the low pressure side is suppressed, and the lubricating oil contained in the fluid is also properly sealed. Further, since the piston ring 4 capable of exhibiting such excellent sealing performance is configured as a single piston ring rather than a combination ring, there is no significant increase in cost and the mounting property to the groove 3 is impaired. It will never happen.

  In the above-described embodiment, the piston ring 4 having a U-shaped cross-sectional shape is shown. However, as the cross-sectional shape of the piston ring, other shapes can also be adopted. As a result, the same performance as in the above embodiment can be obtained. For example, as shown in FIG. 3A, the piston ring 11 has a V-shaped cross section, and as shown in FIG. 3B, the piston ring 12 has an X-shaped cross section, as shown in FIG. Thus, a piston ring 13 having a Y-shaped cross section, a piston ring 14 having a W-shaped cross section as shown in FIG. 3D, and the like are possible. Furthermore, it is possible to make a cross-sectional shape combining any of these U-shape, V-shape, X-shape, Y-shape, and W-shape.

  The piston ring of the piston reciprocating compressor according to the present invention can be applied to any compressor, but is particularly suitable for application to a compressor used in a vehicle air conditioner.

It is a fragmentary sectional view of the piston ring part of the piston reciprocating compressor which concerns on one embodiment of this invention. It is explanatory drawing which shows each operation state of the piston ring of FIG. It is a schematic sectional drawing which shows the various cross-sectional shapes of the piston ring which concerns on this invention. It is a fragmentary sectional view around the piston ring part of the conventional piston reciprocating compressor. It is an expanded sectional view of the A section of FIG. It is explanatory drawing which shows each operation state of the piston ring of FIG.

Explanation of symbols

1 Piston 2 Cylinder 3 Groove 4, 11, 12, 13, 14 Piston ring 5 Cylinder bore 6 Cylinder block

Claims (6)

  An annular piston ring that is mounted in a groove formed on the outer peripheral surface of a piston that is reciprocated in a cylinder of a compressor and is slidably pressed against the inner peripheral surface of the cylinder bore, and has a cross-sectional shape of the piston ring However, for both the compression stroke and the suction stroke, an angle D1 formed by a surface forming a part of the piston ring with respect to the inner peripheral surface of the cylinder bore on the high-pressure fluid existing side in the cylinder, and a part of the piston ring The angle D2 formed by the piston ring surface on the low pressure fluid existence side located on the opposite side to the high pressure fluid existence side with respect to the inner peripheral surface of the cylinder bore has a shape portion satisfying a relationship of D1> D2. Piston ring of a piston reciprocating compressor.   2. The piston ring of a piston reciprocating compressor according to claim 1, wherein the piston ring has a U-shaped, V-shaped, X-shaped, Y-shaped, W-shaped or a combination of any of these in a cross-sectional shape. .   The piston ring of the piston reciprocating compressor according to claim 1 or 2, wherein the cylinder is made of aluminum or an aluminum alloy.   The piston reciprocation according to any one of claims 1 to 3, wherein the piston ring is made of at least one material selected from the group consisting of polytetrafluoroethylene, polyetheretherketone, polyphenyleneamide, and polyamideimide. Piston ring of dynamic compressor.   The piston ring of the piston reciprocating compressor according to any one of claims 1 to 4, wherein the working fluid is a refrigerant.   The piston ring of the piston reciprocating compressor according to any one of claims 1 to 5, wherein the compressor is used for a vehicle air conditioner.

Images