JP2006144845A - Supporting structure for compressor main spindle and needle roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent surface damage of a steel retainer of a needle roller bearing used for a supporting structure for a compressor main spindle; and to make a life of the needle roller bearing longer by improving fatigue strength and destruction strength of the whole retainer. <P>SOLUTION: The steel retainer 4 of the needle roller bearing 1 supporting radial load to the compressor main spindle 11 is made of a steel plate having a carbon content in a range of 0.15-1.10 weight%. The surface damage of the retainer 4 such as wear and seizure can be prevented by applying induction heat treatment composed of induction hardening and induction annealing on the whole retainer including its wall-thickness direction, and longer life is given to the needle roller bearing 1 by improving fatigue strength and destruction strength of the whole retainer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a support structure for a compressor main shaft and a needle roller bearing used in the support structure.

  A compressor such as an air conditioner employs a support structure in which a compression operation member is operated by a main shaft that is rotationally driven at high speed, and a radial load of the main shaft is supported by needle roller bearings arranged in the compressor. Yes (see, for example, Patent Document 1). Needle roller bearings have the advantage that high load capacity and high rigidity can be obtained for a small bearing projection area, and the support structure for the compressor main shaft can be designed compactly.

  In particular, compressors used in automotive air conditioners are required to have improved durability, and in recent years, in order to increase the cooling efficiency of air conditioners in consideration of energy saving and environmental considerations, compressor bearings and other There is a movement to reduce the amount of oil used for internal lubrication. Originally, low-viscosity oil is used for lubrication inside the compressor. Combined with this reduction in the amount of oil, needle roller bearings used for the support structure of the compressor spindle that is driven to rotate at high speed. Has been used under severe lean lubrication conditions.

  On the other hand, many needle roller bearings that support a radial load have needle rollers held by a steel cage. This steel cage can be roughly classified according to its production process. A machined cage produced by machining a pipe material, a press cage for forming a circular blank punched from a plate material by a press process including a drawing process, and a belt There is a welding cage in which a plate is cut into a standard length, and this is bent into an annular shape and welded at both ends. All of these steel cages are formed such that the pocket portion for accommodating the needle rollers is partitioned by the column portion by pocket removal.

  These steel cage materials include steels for low carbon mechanical structures such as S15C having a carbon content of 0.15% by mass or less, SCM415, in consideration of cutting workability and press workability in the manufacturing process. Low carbon cold-rolled steel sheets such as SPC, and low carbon cold-rolled steel sheets such as SPC are often used. In order to prevent surface damage such as wear and seizure, carburizing treatment, carbonitriding treatment, Surface heat treatment such as soft nitriding is performed (see, for example, Patent Document 2). In some cases, carbonitriding is performed as pre-heat treatment or surface hardening such as induction hardening or impact hardening is performed on a portion of the pocket portion that comes into contact with the rolling element (for example, see Patent Document 3). Further, the steel is subjected to surface chemical treatment such as metal plating treatment such as silver or copper, or oxide film treatment such as manganese phosphate treatment (see, for example, Patent Document 4) to improve wear resistance and seizure resistance. Some of the cages are surface modified.

Japanese Patent No. 2997047 (2nd page, Fig. 10-12) Japanese Patent Laid-Open No. 10-46318 (page 3-4) JP 2000-205274 A (page 2-3) Japanese Patent Laid-Open No. 11-303875 (page 2-3)

  In the needle roller bearing used in the compressor main shaft support structure described above, the cage roller moves so that the needle roller slides into the pocket portion with a large contact pressure. When the needle roller bearing has an inner ring or an outer ring raceway, the raceway also makes sliding contact with the inner diameter surface or outer diameter surface of the cage. For this reason, in the case where needle roller bearings are used under severe lean lubrication conditions, such as the support structure of the compressor main shaft of an automotive air conditioner, the sliding contact portions of the steel cage are worn or burned. There is a problem that surface damage such as sticking is more likely to occur. Wear powder generated by wear may be caught between the raceway surfaces of the needle roller and the raceway, and early peeling may occur on the raceway surface or the surface of the needle roller. In addition, there is a problem that the needle roller repeatedly contacts with a large contact pressure on the column portion that divides the pocket portion, so that the entire cage including the column portion is likely to be broken due to fatigue or deformation.

  As for the steel cages described in Patent Documents 2 to 4 described above, the surface modified so as to improve the wear resistance and seizure resistance is about prevention of surface damage such as wear and seizure. Although it has a certain effect, there is a problem that the fatigue strength and fracture strength of the entire cage cannot be increased.

  In addition, the means for modifying the surface of the steel cage by surface heat treatment such as carburizing, carbonitriding, and soft nitriding (Patent Documents 2 and 3) requires the atmosphere to be adjusted. Heat treatment equipment such as a furnace becomes larger, and the heat treatment time becomes longer in order to diffuse carbon and nitrogen. The heat treatment for adjusting the atmosphere is inefficient unless a large number of parts are processed at a time, which necessitates the production of large lots, increases the work in progress, and increases the lead time. Furthermore, waste oil treatment such as quenching oil is necessary, and there is a problem that the burden on the global environment cannot be ignored.

  On the other hand, means for modifying the surface of a steel cage by surface chemical treatment such as metal plating treatment and oxide film treatment (Patent Document 4) increases the surface treatment equipment for plating treatment and the like, and increases the plating film and oxidation. The processing time is increased to form a surface film such as a film and to secure the thickness. In addition, as in the case of the above surface heat treatment, large lot production is forced, work in progress increases, lead time becomes longer, and waste liquid treatment such as plating solution is also required, so the burden on the global environment is also increased. .

  In addition, in surface heat treatment and surface chemical treatment for surface modification, if the processing equipment stops due to a sudden power failure or some trouble, a large number of cages being processed become defective products, and recovery and restoration of the equipment Therefore, there is a problem that a lot of time and cost are wasted. Further, when small lot production is unavoidable, not only the production efficiency is reduced, but also foreign products may be mixed.

  Patent Document 3 describes means for subjecting a rolling bearing retainer having a roller bearing as an example to surface quenching by induction quenching or shock quenching. No heat treatment equipment such as a furnace is required. However, when the rolling bearing retainer described in Patent Document 3 is applied to a needle roller bearing retainer having a large number of pocket portions, it takes much time to quench only the surface of each pocket portion. In addition, there is a problem that the fatigue strength and fracture strength of the entire cage cannot be increased only by surface quenching.

  Therefore, the object of the present invention is to prevent the surface damage of the steel cage of the needle roller bearing used for the support structure of the compressor main shaft, and to increase the fatigue strength and breaking strength of the entire cage, so that the needle roller bearing Is to extend the service life.

  In order to solve the above problems, the present invention comprises a main shaft that rotationally drives a compression operation member of a compressor, and a needle roller bearing that supports the radial load of the main shaft within the compressor. In the support structure of the compressor main shaft in which the needle rollers are held by a steel cage, the entire structure including the thickness direction of the steel cage is subjected to induction heat treatment including at least induction hardening.

  In other words, by using high-frequency heat treatment equipment that does not require atmosphere adjustment and is compact and can handle small-lot production, the whole of the steel cage including the thickness direction is subjected to high-frequency heat treatment including induction hardening. Support structure of the compressor main shaft by handling the steel cage during heat treatment easily and efficiently, preventing surface damage such as wear and seizure, and increasing the fatigue strength and breaking strength of the entire cage The life of the needle roller bearing used in the machine can be extended. In addition, since high frequency heat treatment uses clean electrical energy, there is little burden on the global environment.

  By including induction tempering in the induction heat treatment, the heat treatment step can be inlined. Usually, the induction heat treatment includes induction hardening and induction tempering or furnace tempering, but if induction tempering is selected, induction hardening and induction tempering, both of which have a short processing time, can be easily inlined.

  The needle roller bearing may include at least one of the inner and outer races.

  The surface hardness and internal hardness of the steel cage are preferably in the range of HV350 to 700 in terms of Vickers hardness. The wear resistance and fatigue strength of the entire cage increase as the hardness increases, but if the hardness of the steel cage is less than HV350, sufficient wear resistance and fatigue strength cannot be ensured. In addition, since the fracture strength is high when the hardness is high, the steel is easily broken due to a decrease in toughness, and when the hardness is low, the steel cage is preferably broken by deformation. Therefore, the hardness of the steel cage is preferably HV400 to 650.

  The carbon content of the steel cage is preferably in the range of 0.15 to 1.10% by mass. When the carbon content is less than 0.15% by mass, the surface hardness of the steel cage cannot be sufficiently secured only by high-frequency heat treatment. Further, when the carbon content is increased, workability and weldability are lowered, so the carbon content is preferably 1.10% by mass or less, and preferably 0.50% by mass or less. If the carbon content is 0.30% by mass or less, carbon can be completely dissolved in the iron matrix, and induction tempering and furnace tempering in induction heat treatment can be omitted.

  The compressor main shaft support structure of the present invention is a compact and small lot for needle roller bearings that support the radial load of the main shaft, including the thickness direction of the steel cage, without adjusting the atmosphere. Since induction heat treatment including induction hardening is performed using induction heat treatment equipment that can also handle production, handling of steel cages during heat treatment is performed easily and efficiently, such as wear and seizure. In addition to preventing surface damage, the fatigue strength and breaking strength of the entire cage can be increased, and the life of the needle roller bearing used in the support structure for the compressor main shaft can be extended. In addition, since high-frequency heat treatment uses clean electrical energy, the burden on the global environment can be reduced.

  By including induction tempering in the induction heat treatment, the heat treatment step can be inlined.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a compressor of an automotive air conditioner that employs a support structure for a compressor main shaft according to a first embodiment. This compressor is a double swash plate type compressor that reciprocates a piston 14 as a compression operation member through a shoe 13 that slides on the swash plate 12 by rotation of a swash plate 12 fixed to the main shaft 11. The main shaft 11 that is rotationally driven at high speed is supported by the two needle roller bearings 1 with a radial load and a thrust needle roller bearing 16 with a thrust load in a housing 15 in which refrigerant is present.

  A plurality of cylinder bores 17 are formed in the housing 15 at equal intervals in the circumferential direction, and double-headed pistons 14 are reciprocally accommodated in the bores 17. Each piston 14 is formed with a recess 14a so as to straddle the outer periphery of the swash plate 12, and a spherical shoe 13 is seated on a spherical seat 18 formed on the axially opposed surface of the recess 14a. Some of the shoes 13 are hemispherical, and support the piston 14 so as to be relatively movable with respect to the rotation of the swash plate 12. Thereby, the conversion from the rotational movement of the swash plate 12 to the reciprocating movement of the piston 14 is performed smoothly.

  As shown in FIG. 2, the needle roller bearing 1 that supports the radial load of the main shaft 11 has needle rollers 3 arranged along the raceway surface 2 a of the outer ring 2 held by a steel cage 4. is there. This retainer 4 is a press retainer formed by press working. As shown in FIG. 3, after a circular blank punched from a steel plate is squeezed into a cup shape by a drawing process, bottoming and edge cutting are performed in the forming process. Then, the edge is bent into a cylindrical body with hooks at both ends, and the pocket portion 4a for storing the needle rollers 3 is punched so as to be partitioned by the pillar portion 4b in the pocket removing process, and then the cylinder is formed in the finish molding process. A step is formed at the center of the body.

  The material steel plate of the cage 4 is structural carbon steel S50C having a carbon content of 0.50% by mass, and after being pressed as shown in FIG. The product is subjected to induction heat treatment including induction hardening and induction tempering so that the surface hardness of the product is in the range of HV400 to 650 in terms of Vickers hardness. The material steel plate of the cage 4 may be any material as long as the carbon content falls within the range of 0.15 to 1.10% by mass, and may be other structural carbon steel or tool steel such as SK5. When the carbon content of the raw steel plate is 0.30% by mass or less, induction tempering may be omitted. Further, the induction heat treatment can be performed after the cage 4 is assembled integrally with the outer ring 2 and the needle rollers 3, and furnace tempering may be performed instead of induction tempering.

  FIG. 4 shows a modification of the shape of the steel cage 4. 4 (a) and 4 (b) are examples of a welded cage in which a press cage or a strip with a pocket removed is cut into a standard length, and this is bent into an annular shape and welded at both ends. ) Is an example of a welded cage in which steps are formed by roll forming and pockets are removed, and the ends are welded in the same manner, and FIGS. 4 (d) and 4 (e) are cut out from the pipe material. This is an example of a machined cage. The needle roller bearing 1 using these modified examples and the cage 4 according to the embodiment can have no bearing ring as it is.

  FIG. 5 shows a compressor of an automotive air conditioner that employs the support structure for the compressor main shaft of the second embodiment. This compressor is a swash plate type compressor, and a swash plate 25 supported by a ball 23 and a thrust needle roller bearing 24 on an inclined surface 22a of the connecting member 22 by rotation of the connecting member 22 connected to the main shaft 21. The swinging motion of the swash plate 25 is converted into the reciprocating motion of the single-headed piston 27 via the piston rod 26. In the housing 28, the main shaft 21 is supported by a single needle roller bearing 1 with a radial load and a thrust load is supported by a thrust needle roller bearing 29 via a connecting member 22. The cage 4 of the needle roller bearing 1 is a steel cage in which high-frequency heat treatment is performed on the entire surface including the thickness direction, as in the first embodiment.

  FIG. 6 shows a compressor of an automotive air conditioner that employs the compressor spindle support structure of the third embodiment. This compressor is a swash plate type variable displacement compressor, and the inclination angle of the connecting member 32 connected to the main shaft 31 can be changed by sliding the sleeve 33 fitted in the main shaft 31 in the axial direction. ing. The swinging motion of the swash plate 35 supported on the connecting member 32 by the thrust needle roller bearing 34 is the reciprocating motion of the one-sided piston 37 via the piston rod 36 as in the second embodiment. Converted. In the housing 38, the main shaft 31 supports a radial load by two shell needle roller bearings 1 and a thrust load by a thrust needle roller bearing 39. The cage 4 of the needle roller bearing 1 is also a steel cage in which high-frequency heat treatment is performed on the entire surface including the thickness direction, as in the first embodiment.

1 is a longitudinal sectional view showing a compressor employing a compressor spindle support structure according to a first embodiment; 1 is a longitudinal sectional view showing the needle roller bearing of FIG. The conceptual diagram explaining the press work process of the steel cage of FIG. a, b, c, d, e are sectional views showing modifications of the steel cage of FIG. The longitudinal cross-sectional view which shows the compressor which employ | adopted the support structure of the compressor main shaft of 2nd Embodiment. The longitudinal cross-sectional view which shows the compressor which employ | adopted the support structure of the compressor main shaft of 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Needle roller bearing 2 Outer ring 2a Raceway surface 3 Needle roller 4 Cage 4a Pocket part 4b Column 11 Main shaft 12 Swash plate 13 Shoe 14 Piston 14a Recess 15 Housing 16 Thrust needle roller bearing 17 Bore 18 Spherical seat 21 Main shaft 22 Connecting member 22a Inclined surface 23 Ball 24 Thrust needle roller bearing 25 Swash plate 26 Piston rod 27 Piston 28 Housing 29 Thrust needle roller bearing 31 Main shaft 32 Connecting member 33 Sleeve 34 Thrust needle roller bearing 35 Swash plate 36 Piston rod 37 Piston 38 Housing 39 Thrust needle roller bearing

Claims (6)

  A compressor main shaft comprising a main shaft for rotationally driving a compression operation member of the compressor and a needle roller bearing for supporting the radial load of the main shaft in the compressor, and the needle roller of the needle roller bearing held by a steel cage. The support structure for the compressor main shaft is characterized in that the whole heat treatment including the thickness direction of the steel cage is subjected to induction heat treatment including induction hardening at least.   The support structure for a compressor main shaft according to claim 1, wherein the induction heat treatment includes induction tempering.   The support structure for a compressor main shaft according to claim 1 or 2, wherein the needle roller bearing includes at least one of the inner and outer races.   The support structure of the compressor main shaft according to any one of claims 1 to 3, wherein the steel cage has a surface hardness and an internal hardness in the range of HV350 to 700 in terms of Vickers hardness.   The support structure of the compressor main shaft according to any one of claims 1 to 4, wherein the steel cage has a carbon content in a range of 0.15 to 1.10 mass%.   The needle roller bearing used for supporting the radial load of the main shaft in the compressor main shaft support structure according to any one of claims 1 to 5.

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