JPH11351246A - Thrust needle roller bearing for swash plate type compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability by reducing the variance of the contact of a needle roller with a bearing ring of a thrust needle roller bearing to be built in and used for a swash plate type compressor. SOLUTION: A thrust needle roller bearing is provided with a first bearing ring 20a to be fitted to a stationary member, a second bearing ring 20b to be rotated together with a rotary member, a plurality of needle rollers 30 built in between the first bearing ring 20a and the second bearing ring 20b, and a holder 40 to hold a plurality of needle rollers 30 with equal intervals in the circumferential direction, and a maximum contact stress part (a) of the needle rollers 30 with the first bearing ring 20a is approximately agreed with a maximum contact stress part (b) of the needle rollers 30 with the second bearing ring 20b in the radial direction of the bearing rings.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thrust needle roller bearing, and more particularly, to a thrust load applied to a main shaft of a swash plate type compressor used for an air conditioner (car air conditioner) of an automobile. Needle thrust roller bearings for

[0002]

2. Description of the Related Art A compressor for a car air conditioner receives a driving force from an engine, draws in heat in a cabin by an evaporator, sucks and compresses a low-temperature and low-pressure refrigerant gas, and compresses the high-temperature and high-pressure gas. It is responsible for sending out to the capacitor. FIG. 5 exemplifying a schematic configuration of a swash plate type compressor.
7 to FIG. 7, FIG. 5 shows a double swash plate type, FIG. 6 shows a single swash plate type, and FIG.

The swash plate type compressor (1) shown in FIG.
The piston reciprocates via a shoe sliding on a swash plate. A main shaft (4) to which a swash plate (3) is fixed is mounted in a housing (2) via a radial bearing (5). Supported rotatably. A plurality of cylinder bores (6) are formed in the housing (2) at equal intervals in the circumferential direction, and a double-headed piston (7) is slidably accommodated in each bore (6). A recessed portion (8) is provided at the center of each piston (7) so as to straddle the outer periphery of the swash plate (3).
A spherical seat is formed on an axially facing surface of the concave portion (8), and a spherical or hemispherical shoe (9) is seated. A shoe (9) is interposed between the swash plate (3) and the piston (7) to smoothly convert the rotational movement of the swash plate (3) into a reciprocating movement of the piston (7).

The swash plate (3) is fixed to the main shaft (4) and rotates together with the main shaft (4). Since the swash plate (3) functions to reciprocate the piston (7) as described above, a thrust load is generated in the axial direction of the main shaft (4). Therefore, the swash plate (3) and the housing (2)
A thrust bearing (10) is interposed between this and the other. As this thrust bearing, a needle roller bearing is generally used.

[0005]

The compressor for a car air conditioner is lubricated by oil (refrigeration oil) circulating in the cycle together with the refrigerant. That is, refrigerating machine oil is mixed in the refrigerant, and the oil is carried by the refrigerant circulating in the system. It is well known that freon-based refrigerants have the property of dissolving oil well. Lubrication is performed by supplying the oil dissolved in the refrigerant to the friction portion.

[0006] However, the larger the amount of oil is, the better for lubrication, but the oil circulating together with the refrigerant has a negative effect on the cooling performance. Therefore, an appropriate amount of circulating oil must be selected. It is sealed so that the oil circulation rate is several percent. Therefore, the bearings used in the compressor are under stricter lubrication conditions than general oil lubrication because the refrigerant is mixed therein and the amount of the lubricant is reduced. As a result, peeling damage may occur on the raceway,
There is a problem that early peeling occurs.

[0007] In addition, since the race of the thrust needle roller bearing is generally formed by pressing a thin steel plate, the accuracy is relatively lower than that obtained by cutting, and in addition, as a result of heat treatment, warpage occurs. May occur.
Warpage of the bearing ring leads to contact with the needle rollers, that is, variation in the maximum contact stress portion. Here, with reference to FIG. 3, the maximum contact stress portion (a) between one of the races (20a) and the needle rollers (30) of the pair of races (20a) (20b), If the position of the maximum contact stress portion (b) between the other bearing ring (20b) and the needle roller (30) does not match in the radial direction of the bearing ring, as shown in FIG. A force acts to tilt the needle roller (30) with respect to the normal rotation axis. As a result, the needle rollers (30) are skewed to cause seizure, or to cause problems such as early removal of the needle rollers and the raceway surface.

Accordingly, an object of the present invention is to improve the durability of a thrust needle roller bearing used in a compressor for an air conditioner by reducing the variation in the contact position between the needle roller and the race. To make it happen.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, a thrust needle roller bearing for a swash plate type compressor according to the present invention supports a thrust load acting on a main shaft rotatably supported in a compressor housing. A thrust needle roller bearing for rotating a rotating member together with a first bearing ring, a second bearing ring attached to a stationary member, between the first bearing ring and the second bearing ring A plurality of incorporated needle rollers, comprising a retainer for holding the plurality of needle rollers at equal intervals in the circumferential direction, the maximum contact stress site between the needle rollers and the first raceway, The maximum contact stress portion between the needle roller and the second race is substantially matched in the radial direction of the race. As a result, the needle rollers come into contact with the first and second races at substantially the same radial position, and the force component for breaking the normal posture of the needle rollers is reduced as much as possible. Therefore, skew is less likely to occur in the needle rollers, and a stable rolling posture can be maintained.

The maximum contact stress portion can be arranged at any position in the radial direction of the bearing ring, but since the circumferential speed of the bearing ring is smaller on the inner diameter side than on the outer diameter side, the position of the needle roller In order to stabilize, it is advantageous that the maximum contact stress portion is located closer to the inner diameter side of the bearing ring as in the second aspect of the present invention.

As a specific means for setting the maximum contact stress portion at a desired position, for example, as in the invention of claim 3, the raceway ring is made of a thin steel plate, and the portion where the raceway surface is formed is replaced with the raceway surface. The ring is gradually inclined from the small diameter side to the large diameter side in the radial direction of the ring. When the maximum contact stress portion is located closer to the inner diameter side of the bearing ring (claim 2), as in the invention of claim 4, the inclination direction of the raceway surface is set to the larger diameter side of the bearing ring. The more it goes, the further away from the needle rollers.
Further, the inclination angle of the raceway surface is preferably set to 1.0 degree or less.

[0012]

FIG. 1 shows an embodiment of a thrust needle roller bearing (10) used in the swash plate type compressor (1) exemplified in FIG. 5 described above. This thrust needle roller bearing (10) is configured by incorporating a plurality of needle rollers (30) held by a retainer (40) between a pair of races (20a) (20b). One bearing ring (20a) has a cylindrical portion (24a) on the outer diameter side, and the other bearing ring (20b) has a cylindrical portion (24b) on the inner diameter side. By caulking these cylindrical portions (24a) (24b) at several locations around the thrust needle roller bearing (10), unit handling becomes possible.

One of the races (20a) is attached to, for example, a housing (2) as a stationary member, and is made of a thin steel plate, and one surface is a raceway surface (22a). The other race (20b) that contacts the swash plate (3) is made of a thin steel plate and has a raceway surface (22b) formed on one surface.

The raceway surface (22a) of the race (20a) (20b)
(22b) has a surface hardened layer formed by carbonitriding or carburizing and quenching. The durability can be improved by forming a surface hardened layer on the raceway surface (26) by heat treatment such as carbonitriding or carburizing and quenching. In this case, it is preferable that the amount of retained austenite in the surface layer of the bearing ring (22) be 15% by volume or more.

A plurality of needle rollers (30) that roll on the raceway surfaces (22a) (22b) are respectively rotatably accommodated in pockets of the retainer (40). The retainer (40) is formed by molding a thin steel plate into a shape as illustrated in FIG.

FIG. 2 shows an enlarged cross-section through the column of the retainer (40). As shown by the solid line in the drawing, it is expected that the needle rollers (30) and the raceway surfaces (22a) (22b) are in uniform line contact over the entire length of the needle rollers (30). However, as described above, the maximum contact stress portion usually varies in practice due to factors such as warpage of the bearing ring. As shown in FIG.
If the maximum contact stress portions (a) and (b) between the needle rollers (30) and the raceway surfaces (22a) and (22b) are shifted in the radial direction of the race, the needle rollers (30) may cause skew. Become. Therefore, it is desirable that both the maximum contact stress portions (a) and (b) coincide in the radial direction of the bearing ring. FIG.
(B) shows a case where the maximum contact stress portions (a) and (b) are made to coincide with each other at the longitudinal center portion of the needle roller (30).
As shown by the two-dot chain line in FIG.
a) The distance between the opposing raceway surfaces (22a) and (22b) of (20b) is set to be larger on the inner diameter side than on the outer diameter side, so that the needle roller (30) and each The maximum contact stress portion with the raceway surfaces (22a) (22b) can be located closer to the inner diameter side of the raceway.

FIG. 4 shows only the bearing ring (20b) in FIG. 2 and is somewhat exaggerated to explain the specific configuration of the raceway surface (22b). The bearing ring (20b) is
The annular portion forming b) is inclined with a downward gradient from the inner diameter side to the outer diameter side. As a result, the track surface (22b)
Also, the bearing ring (20b) is inclined with a downward slope from the inner diameter side to the outer diameter side. The inclination angle θ is preferably set to 1.0 degree or less. The degree of inclination of the raceway surface (22b) is 1.0
If the temperature exceeds the range, the contact with the needle roller may be an edge load, or the needle roller may hinder stable rolling. The inclination of the raceway surface (22b) is not limited to a linear inclination as shown, but may be a gentle convex curve or a concave curve.

[0018]

As described above, according to the present invention, the maximum contact stress portion between the needle roller and the first race is
By making the maximum contact stress portion of the needle roller and the second contact ring substantially coincide with each other in the radial direction of the bearing ring, the force for tilting the needle roller with respect to the normal rotation axis is reduced. Less likely to cause skew. Therefore, damages such as seizure are prevented, and the durability of the thrust needle roller bearing and thus the swash plate type compressor using the same are improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a thrust needle roller bearing.

FIG. 2 is an enlarged sectional view.

FIG. 3 is a sectional view (A) and front views (B) and (C) for explaining skew of a needle roller.

FIG. 4 is an enlarged sectional view of a bearing ring.

FIG. 5 is a longitudinal sectional view of a double-swash plate type swash plate compressor.

FIG. 6 is a longitudinal sectional view of a single-swash plate type swash plate compressor.

FIG. 7 is a longitudinal sectional view of a single-swash plate type variable displacement swash plate compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Swash plate type compressor 2 Housing (stationary member) 3 Swash plate (rotating member) 4 Main shaft (rotating member) 5 Radial bearing 6 Cylinder bore 7 Piston 8 Depression 9 Shoe 10 Thrust bearing 20a Track ring 22a Track face 20b Track ring 22b Track face 24 Flat plate part 26 Cylindrical part 30 Needle roller 40 Cage a, b Maximum contact stress area

Claims (6)

[Claims] 1. A thrust needle roller bearing for supporting a thrust load acting on a main shaft rotatably supported in a housing of a compressor, the thrust needle roller bearing comprising a first bearing ring rotating with a rotating member, and a stationary member. The second race attached to the, the plurality of needle rollers incorporated between the first and second races, and to maintain the plurality of needle rollers at equal intervals in the circumferential direction And a maximum contact stress site between the needle roller and the first race, and a maximum contact stress site between the needle roller and the second race, in the radial direction of the race. Thrust needle roller bearings for swash plate compressors, characterized in that they match. 2. The thrust needle roller bearing for a swash plate type compressor according to claim 1, wherein said maximum contact stress portion is located closer to the inner diameter side of the bearing ring. 3. The bearing ring according to claim 1, wherein the bearing ring is made of a thin steel plate, and a bearing surface in contact with the needle rollers is gradually inclined from a smaller diameter side to a larger diameter side in a radial direction of the bearing ring. Thrust needle roller bearing for swash plate type compressor. 4. The thrust needle roller bearing for a swash plate type compressor according to claim 3, wherein said raceway surface is inclined in a direction away from the needle rollers as it goes to the large diameter side of the race. 5. The thrust needle roller bearing for a swash plate type compressor according to claim 3, wherein an inclination angle of said raceway surface is 1.0 degree or less. 6. The thrust needle roller bearing for a swash plate type compressor according to claim 1, wherein the amount of retained austenite in the surface layer of said race is at least 15% by volume.