JP2012057474A - Refrigerant compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a highly-reliable and long-life hermetic refrigerant compressor using a bearing material having high wear resistance and seizure resistance by preventing wear and seizure of a bearing part even in a state where there is a possibility that lubricating oil is not supplied temporarily with a refrigerant containing no chlorine, such as an HFC system or HC system refrigerant.SOLUTION: In the hermetic refrigerant compressor for a refrigeration cycle, at least one bearing for a rotating shaft and a crank uses a member with a bearing bush press-fitted into a bearing member and the surface then finished, the bearing bush being formed by molding a composite body, in which an alloy sintered layer containing no lead and a self lubricating material are combined with a flat back plate, in a cylindrical shape.

Description

  The present invention relates to a refrigerant compressor.

  With closed-type refrigerant compressors, with the use of HFC and natural refrigerants as a countermeasure for the global environment, the internal pressure of the compressor becomes high in the compressor operating atmosphere and the load on the bearing is increasing. Since the shaft and the rotating shaft are in direct contact with each other, boundary lubrication is likely to occur. In addition, the boundary lubrication state occurs even when the compressor is started or when excessive refrigerant is mixed. Under such boundary lubrication conditions, conventional metal bearings, resin bearings, surface-treated shafts, and the like were prone to seizure and burring. As a method of reducing the bearing load, there is a means of increasing the inner diameter of the bearing or extending the length of the bearing. However, a hermetic compressor with a built-in motor has limitations because the space required for the bearing is limited. It was.

  As means for improving the wear resistance and seizure resistance of the bearing portion, the bearing portion that supports the orbiting scroll of the scroll compressor is known, and the following examples are known. As a means for solving the problem of running out of oil at startup, Patent Document 1 discloses that an oil retaining portion is provided in order to speed up the oil supply to the metal bearing. Patent Document 2 discloses a method of forming a bearing with an oil-impregnated ceramic material.

  Patent Document 3 also uses a self-lubricating material such as PTFE (Teflon (registered trademark, hereinafter the same)) resin as the material of the eccentric bush mechanism for driving the orbiting scroll to avoid metal contact. Means are shown that do not cause seizure. Further, Patent Document 4 describes impregnation of a bronze alloy in order to make it easy to form an oil film in the lubricating oil in the pores of the carbonaceous substrate which is difficult to seize even in the boundary lubrication state, and further, the composition and structure of the bronze alloy, the amount of impregnation By adjusting so that the friction coefficient can be reduced and the wear resistance can be obtained, a bearing having excellent sliding characteristics can be obtained, and a highly reliable refrigerant compressor can be obtained. Furthermore, in refrigerant compressors that are exposed to unlubricated or harsh sliding conditions, when used in carbonaceous substrates and lubricating oils that have a low coefficient of friction and good wear resistance even in non-lubricated or harsh sliding states In addition, in order to prevent the lubricating oil from being discharged through pores remaining in the carbonaceous base material containing carbon and making it difficult to form an oil film, a refrigerant compressor using a member in which a carbonaceous base material is melt-impregnated with a bronze alloy is used. Therefore, a highly reliable and long-life refrigerant compressor can be provided by keeping the coefficient of friction small under no-lubrication or severe sliding conditions and minimizing wear.

JP 62-70682 A (Patent Document 1) JP 63-268993 A (Patent Document 2) Japanese Utility Model Publication No. 59-114477 (Patent Document 3) JP 2002-213356 A (Patent Document 4)

  In Patent Document 1 and Patent Document 2 described above, when a bush type bearing is made of ceramic, there are drawbacks such as that it cannot be made thin due to its brittleness, difficult to process, and expensive. Furthermore, the publication discloses a conventional method in which a self-lubricant such as ethylene tetrafluoride or molybdenum disulfide is applied or impregnated on the surface of a metal bearing based on copper, aluminum, tin, or lead. Since the base is made of metal, when the oil runs out, the metals come into contact with each other and the wear resistance and seizure resistance are not sufficient. Further, since the self-lubricant is applied to the surface or impregnated from the surface, it is easy to come off by sliding and has a drawback that it is difficult to exert a sufficient effect over a long period of time.

  Patent Document 3 discloses a means for avoiding metal contact and causing seizure by using a self-lubricating material as an eccentric bush mechanism material for driving the orbiting scroll, but PTFE (Teflon) is a high temperature. It is easy to cause thermal deformation creep. Although the bearing ambient temperature of the compressor is around 100 ° C., the bushing itself generates heat due to sliding, so that the temperature is considerably higher than the ambient temperature, and creep occurs when subjected to a load at this temperature. In order to increase the deformation strength, means for impregnating the sintered alloy with PTFE (Teflon) is also shown. However, as described above, metal contact is inevitable.

  Moreover, although patent document 4 can provide a highly reliable and long-life refrigerant compressor, the problem of the cost increase of bearing material cost arises.

  The present invention prevents wear and seizure of the bearing portion even in a state where the lubricating oil may not be temporarily supplied in a refrigerant not containing chlorine, such as an HFC or HC refrigerant, and has high wear resistance. It is to provide a highly reliable and long-life hermetic refrigerant compressor using a bearing material having heat resistance and seizure resistance at low cost.

Specific means for solving the problems are as follows.
(1) In a refrigerant compressor of a refrigeration cycle in which refrigerant is compressed by compression means driven by a crank of a rotating shaft and liquefaction and evaporation are repeated, at least one bearing for the rotating shaft and crank is a back metal. A refrigerant compressor characterized in that a cylindrically-shaped wound bush consisting of a two-layer structure of a copper-based alloy sintered layer in which a solid lubricant is dispersed is used as a bearing material.
(2) The hermetic refrigerant compressor characterized in that the solid lubricant contained in the bearing material according to claim 1 is made of graphite.
(3) The hermetic refrigerant compressor characterized in that the solid lubricant contained in the bearing material according to claim 1 is formed of graphite.
(4) The hermetic refrigerant compressor according to claim 1, wherein HFC refrigerant and HC refrigerant are used as the refrigerant.

  The refrigerant sealed in the compressor of the present invention is a refrigerant that does not contain chlorine, such as an HFC or HC refrigerant, and the lubricity of the refrigerant cannot be determined. A carbon material can be raised as a material that is difficult to seize even in the boundary lubrication state, but it is very expensive, and a low hardness may lead to an increase in the amount of wear. Further, the carbon material is a sintered material, and if there are pores, the refrigerating machine oil penetrates into the pores and the oil film forming ability is reduced, so pore impregnation is necessary. Examples of the impregnating material include lead, antimony, and the like, which are low melting point materials. As a bearing material, bronze-impregnated carbon is excellent in wear resistance and seizure resistance, but is very expensive. As a low-cost bearing material, a wound bush can be raised, but a normal material is a material obtained by coating an alloy sintered material with a resin. However, when the resin coating is operated under a high load condition, seizure of the sliding portion occurs.

  As an improvement measure, the bronze alloy sintered material contains graphite as a solid lubricant and aims at the same effect as the bronze-impregnated carbon material.

  This is because the rotating shaft is tilted by the bearing due to the action of fluid pressure during compression of the compressor, and graphite is uniformly distributed in the bronze alloy even when an oil film cannot be formed. Wear and seizure can be prevented by solid lubrication. In addition, when the sliding condition is severe such as a non-lubricated state at the time of start-up or the like, a highly reliable bearing can be provided without causing deformation or deterioration even when the bush becomes a high temperature state due to sliding heat.

  According to the present invention, in a bearing portion of a hermetic refrigerant compressor where it is difficult to supply lubricating oil or there is a possibility that lubricating oil may not be temporarily supplied, wear and seizure are prevented by using a material having excellent lubricity. However, the durability of the compressor can be remarkably enhanced. In addition, it is extremely useful for improving the reliability of air conditioners, refrigerators, and water heaters in response to sudden oil shortages. Furthermore, since the machinability is good, it is possible to cope with mass productivity and to reduce the cost.

It is a longitudinal cross-sectional schematic diagram of the scroll compressor using the bearing bush material of this invention. It is a fragmentary sectional view which shows the internal structure of the bearing bush material of this invention. 3 shows the results of wear tests conducted on various metals and alloy materials in order to confirm the wear resistance of the bronze powder constituting the bearing bush material of the present invention. It is an evaluation result of seizure resistance and wear resistance of the bearing material of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, a scroll type compressor which is a kind of hermetic compressor will be described as an example. The scroll-type compressor is connected to the inside of the hermetic container (1) through a crankshaft (6) with a compression mechanism disposed above and a motor (8) disposed below. The compressor section includes a fixed scroll (4) in which a spiral wrap (4b) is erected on the end plate (4a) and a revolving scroll (3) in which the spiral wrap (3b) is erected on the end plate (3a). The suction port (4c) and the discharge port (4d) are disposed in the outer peripheral portion of the fixed scroll (4) and the central portion, respectively. The crankshaft (6) is supported by the center bearing portion (5a) of the frame (5), and the crank (6a) protruding from the tip of the crankshaft (6) is inserted into the bearing portion (3c) of the orbiting scroll (3). Is engaged. The Oldham coupling (7a) as an anti-rotation mechanism is a joint that the orbiting scroll (3) orbits without rotating with respect to the fixed scroll (4). ) And the keyway (5c) of the frame (5). Therefore, when the crankshaft (6) is rotated by the lower motor (8), the orbiting scroll (3) does not rotate due to the eccentric rotation of the crank (6a), but performs the orbiting motion with respect to the fixed scroll (4). The refrigerant gas sucked from 4c) is compressed, and the compressed gas is discharged from the discharge port (4d). The orbiting scroll (3) is provided with a bearing portion (3c), and the frame (5) is provided with a bearing portion (5a), both of which are supplied with circulating lubricating oil. When the pressure is high, the supply of lubricating oil is insufficient, and damage such as wear and seizure is likely to occur.

  As shown in FIG. 2, the bearing bush material of the present invention has a structure in which the surface of the back metal (9) is impregnated and sintered with bronze alloy powder (10) as an alloy sintered layer and graphite (11) as a solid lubricating material. Yes. The bearing bush material having such a structure is processed into a cylindrical shape to be wound bushes (3e) and (5b), and after pressing into the orbiting scroll (3) and the frame (5), an appropriate amount of the surface is removed by grinding, Finished to a specified dimensional accuracy. The winding bushes (3e) and (5b) are made of graphite, so the surface of the rotary shaft and the surface of the winding bushes (3e) and (5b) must be in perfect metal contact even when they are in solid contact. Therefore, seizure hardly occurs. Further, since the bearing of the present invention has a structure in which a bronze alloy powder (10) and graphite (11) are impregnated and fired on a back metal (9), the plate thickness can be constituted by 1.5 to 3.0 mm or press-fitted. There are no cracks or cracks of time. Therefore, the bearing bush can be made thinner than the case where the bearing bush is made of a ceramic or carbon stripping material.

  The bearing ambient temperature of the hermetic refrigerant compressor is around 100 ° C., and the actual bearing portion is several tens of degrees Celsius higher than the ambient temperature and is 120 to 160 ° C. PTFE is used as a self-lubricating resin in general winding bushes. Is used. However, when a high surface pressure is applied in a non-lubricated state, such as when the compressor is started, the temperature of the bearing portion becomes 200 ° C. or higher, and the bearing strength of a resin such as PTFE is significantly reduced due to thermal deformation. The bearing bush of the present invention contains graphite as a solid lubricant in a bronze alloy and is impregnated and fired with heat resistance and self-lubricating properties, so it is not worn or seized even in a non-lubricated state at start-up. There is no thermal deformation. Therefore, when sliding conditions are severe such as a non-lubricated state at the time of start-up, a highly reliable bearing can be proposed without causing deformation or deterioration even when the bearing bush material becomes hot due to sliding heat.

  FIG. 3 is a graph showing the results of the mixed lubrication of R410A refrigerant + POE oil in the case of impregnating a carbonaceous substrate with various alloys (see Table 1) for the purpose of evaluating the performance of the bronze alloy powder (10) which is an alloy sintered layer. It shows the wear amount after a load resistance test in which a sliding speed of 2 m / s and a surface pressure of up to 100 MPa were applied at a load speed of 0.15 MPa / s.

  A sintered metal using bronze (90% copper, 10% tin) has the least amount of wear. In addition, there are Sb, bronze + V, and Ti. However, since Sb is an applicable substance of the PRTR method and V and Ti are expensive, it is considered that a bronze alloy is desirable for the alloy sintered layer.

  FIG. 4 summarizes the wear amount of the test piece after the load resistance test for the graphite-containing copper-based sintered material of the present invention (Example 2) and the bearing bush material containing PTFE resin (Comparative Example 9) as a lubricating layer. It is a result. The test conditions were as follows: maximum surface pressure: 98 N, overload speed 0.15 MPa, speed 1.2 m / s, ambient temperature 80 ° C., refrigerant: R410A and refrigerating machine oil: POE oil. As a result, when the wear amount of the fixed piece is compared, the bearing bush material having the graphite-containing copper-based alloy sintered material of this example is 23.7 μm in Example 2 and 33.7 μm in Comparative Example 9, The amount of wear is suppressed to about 2/3 or less compared to the comparative example.

  As described above, if the above-described bearing bush material is used as a bearing material, it can be applied to a hermetic refrigerant compressor that uses HFC refrigerant or HC refrigerant having poor lubricity because it does not contain chlorine. High performance and high reliability can be provided. Furthermore, the present invention can be applied to an air conditioner, a refrigerator, and a water heater using the above-described hermetic refrigerant compressor, and can provide high performance and high reliability.

DESCRIPTION OF SYMBOLS 1 Airtight container 2 Balance weight 3 Orbiting scroll 3a, 4a End plate 3b, 4b Wrap 3c, 5a Bearing part 3d, 5c Key groove 3e, 5b Rolling bush 3f, 5d Bearing material 4 Fixed scroll 4c Inlet 4d Discharge port 5 Frame 6 Crank Shaft 6a Crank 7 Oldham ring 7a Oldham joint 8 Motor 9 Back metal 10 Bronze alloy powder 11 Graphite

Claims (4)

  In a refrigerant compressor of a refrigeration cycle in which refrigerant is compressed by compression means driven by a crank of a rotating shaft and repeatedly liquefied and evaporated, at least one bearing for the rotating shaft and crank disperses a back metal layer and a solid lubricant. A refrigerant compressor using a wound bush formed of a two-layer structure of a copper-based alloy sintered layer formed into a cylindrical shape as a bearing material.   The hermetic compressor according to claim 1, wherein the copper-based sintered alloy is made of copper and tin.   2. The hermetic refrigerant compressor according to claim 1, wherein the solid lubricant contained in the bearing member is formed of graphite.   2. The hermetic refrigerant compressor according to claim 1, wherein an HFC refrigerant and an HC refrigerant are used as the refrigerant.

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