JPH11351145A - Needle roller bearing for swash plate compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict lopsided wear of a contact area between a holder and a shaft. SOLUTION: A holder 3 is completed through the processes of pressing an SPC thin steel plate (molding into a basic section shape), punching a pocket 3a, welding at both ends (W portions), heat treatment (soft nitriding) and barrel machining in sequence. The surface roughness of the inner diameter face (the inner diameter face of an inner diameter portion 3c3) of the holder 3 completed in this way is 1.0 μmRa or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a needle roller bearing for a swash plate type compressor for performing a suction / compression operation of a working medium in an air conditioner of an automobile or the like.

[0002]

2. Description of the Related Art At present, a cooling system used in an automobile is a vapor compression system. A vapor compression refrigeration cycle is composed of a compressor, a condenser, a liquid receiver, an expansion valve, and an evaporator, and a working medium (refrigerant) is provided in the closed refrigeration cycle.
Circulates from a low heat source (vehicle air) to a high heat source (outside air)
Cooling is performed by transferring heat to

[0003] As a compressor which is a component of the refrigeration cycle, a swash plate type compressor as illustrated in FIGS. 5 to 7 is used.

In the swash plate type compressor shown in FIG. 5, a piston 1 is rotated by rotating a double-sided inclined plate 11 fixed to a rotating shaft 10.
2 is a type (both swash plate type) in which a refrigerant is sucked and compressed by sliding back and forth in the axial direction within the cylinder chamber 13a. The cylinder block 13 includes a plurality of cylinder chambers 13a.
Are formed at equal circumferential intervals, and the double-headed pistons 12 are accommodated in the respective cylinder chambers 13a so as to be slidable in the axial direction. Shoe 14 is interposed between both sides of the swash plate 11 and the piston 12, and the rotational movement of the swash plate 11 is converted into a reciprocating movement of the piston 12 via the shoes 14.

[0005] When power is input to the rotating shaft 10, the rotating shaft 10 and the swash plate 11 rotate integrally, and the rotation is supported by the needle roller bearings 15 and 16. That is,
Since the swash plate 11 (and the rotating shaft 10) is loaded with an axial load accompanying the compression operation of the refrigerant via the piston 12, this is supported by the thrust needle roller bearing 15,
The radial load of the rotating shaft 10 (and the swash plate 11) is supported by a radial needle roller bearing 16.

The swash plate type compressor shown in FIG. 6 reciprocally slides a piston 22 through a rod 24 (provided with a shoe) by a single-sided inclined plate 21 fixed to a rotating shaft 20 (single-swash plate). ), And the load is supported by the thrust needle roller bearing 25 and the radial needle roller bearing 26.

The swash plate compressor shown in FIG. 7 reciprocates a piston 32 via a rod 34 (provided with a shoe) by a swash plate 31 attached to a rotating shaft 30 so as to be angularly displaceable. The load is supported by thrust needle roller bearings 35 and radial needle roller bearings 36.

The lubrication of the needle roller bearings 15, 16 (25, 26, 35, 36) incorporated in the swash plate compressor as described above is performed by a lubricant contained in the refrigerant circulating in the refrigeration cycle. , The amount of lubricant is relatively small,
In addition, since the liquefaction and vaporization of the lubricant are repeated by the suction and compression operations of the compressor, the lubrication conditions inside the bearing are severe.

[0009]

In the swash plate type compressor as described above, the needle roller bearings for supporting the rotating shaft in the radial direction (the needle roller bearings 16, 26, 3 shown in FIGS. 5 to 7).
As 6), shell-type needle roller bearings are often used from the viewpoint of space saving and cost reduction. Usually, a track surface is provided directly on the outer peripheral surface of a rotating shaft without using an inner ring. In addition, the cage is often made of thin steel plate, and if necessary,
Either roller guide or shaft guide is selected.

As described above, since this type of needle roller bearing is operated under severe lubrication conditions, when the shaft guide is selected as the guide type of the cage, the inner diameter surface of the cage rotates when the bearing rotates. Sliding contact with the outer peripheral surface of the shaft tends to cause uneven wear at the contact portion between the two. On the other hand, when the roller guide is selected as the guide type of the cage, the cage and the rotating shaft are not in contact with each other by design, but in the cage made of thin steel plate, due to the variation in dimensional tolerance, when the bearing rotates,
The inner diameter surface of the retainer may make sliding contact with the outer peripheral surface of the rotating shaft, and the same problem as described above may occur.

Accordingly, an object of the present invention is to provide a radial needle roller bearing of this type in which uneven wear of a sliding contact portion between a retainer and a rotary shaft is suppressed, thereby improving the life of the bearing.

[0012]

SUMMARY OF THE INVENTION To achieve the above object, the present invention is incorporated in a swash plate type compressor in which a piston is reciprocally slid in an axial direction in a cylinder by a rotating operation of a swash plate provided on a rotating shaft. In a needle roller bearing that supports a rotating shaft in a radial direction with respect to a fixed member, a roller is rotatably interposed between an outer ring fixed to the fixed member and a raceway surface of the outer ring and an outer peripheral surface of the rotating shaft. A plurality of needle rollers, and a cage made of a thin steel plate that holds the needle rollers at predetermined circumferential intervals, wherein a surface roughness of an inner diameter surface of the cage is 1.0 μmRa or less. Here, “Ra” is JISB
0601 indicates the center line average roughness.

The inner surface of the cage has a surface roughness of 1.0 μmR.
By setting it to a or less, aggressiveness to the outer peripheral surface of the rotating shaft is reduced, and uneven wear of the outer peripheral surface of the rotating shaft is suppressed, and at the same time, the frictional force of the contact portion is reduced. Uneven wear of itself is also suppressed.

The retainer may be formed by drawing a thin steel plate, but is formed into a required cross-sectional shape, and both ends of a flat thin steel plate having a plurality of pockets for accommodating needle rollers are welded to each other. It is preferable to use a welded cage formed as a ring from the viewpoint of simplifying the manufacturing process.

As the outer ring, it is preferable to use a shell-type outer ring made of a thin steel plate from the viewpoint of reducing the sectional height and cost. In this case, by setting the surface roughness of the raceway surface of the outer ring to 0.63 μmRa or less, an appropriate oil film is formed at a contact portion between the raceway surface of the outer ring and the rolling surface of the needle roller, and the raceway surface and the rolling surface are secured. Damage such as peeling and smearing of the moving surface can be prevented to extend the life.

Further, by providing inward flanges at both ends of the shell-type outer ring and forming at least one of the flanges into a tapered shape which is open toward the outer side of the bearing, the lubricant inside the bearing can be supplied to the inside of the bearing. The flowability can be enhanced, and the interference between the retainer and the flange can be prevented.

Furthermore, by providing at least one of both ends of the outer diameter surface of the shell type outer race with a tapered portion whose diameter is gradually reduced toward the outer side of the bearing, the coaxiality at the time of press-fitting the bearing into the fixed side member is reduced. When the fixed-side member is made of a soft material such as an aluminum material, the possibility of damaging the fixed-side member during the press-fitting operation can be eliminated.

[0018]

Embodiments of the present invention will be described below.

FIG. 1 shows a shell type needle roller bearing. This needle roller bearing supports, for example, a rotating shaft 10 rotatably in a radial direction with respect to a fixed member in a swash plate type compressor shown in FIG. The fixed side member is
In the configuration shown in FIG. 5, a member (13b) constituting the inner diameter wall of the cylinder block (13) is provided.
b) is usually formed of an aluminum material.

The needle roller bearing has a stationary member (13
b) a shell-type outer ring 1 press-fitted and fixed, a plurality of needle rollers 2 rotatably interposed between the raceway surface 1a of the outer ring 1 and the outer peripheral surface of the rotary shaft 10, and the needle rollers 2 And a retainer 3 made of a thin steel plate that is retained at equal circumferential intervals. Inward flanges 1b and 1c are formed at both ends of the outer race 1, respectively.
Needle roller 2 and retainer 3 are formed by these flange portions 1b and 1c.
Is restricted in the axial direction.

The outer race 1 is formed by, for example, deep drawing from SCM thin steel plate (forming into a cup shape) → punching the bottom of the cup (forming the flange 1b) → heat treatment (carburizing or carbonitriding).
→ Annealing the periphery of the cup entrance → Barreling → Bending the periphery of the cup entrance (forming the flange 1c)
The configuration shown in FIG. 1 is completed. The surface roughness of the raceway surface 1a of the outer ring 1 thus completed is 0.63 μm Ra.
It is as follows. The bending process of the flange portion 1c is performed after the needle rollers 2 and the retainer 3 are assembled into the raceway surface 1a.

As shown in FIG. 2, the cage 3 is provided with a plurality of pockets 3a for accommodating the needle rollers 2 at equal circumferential intervals.
The both sides of the pocket 3a in the axial direction are annular portions 3b, and the both sides in the circumferential direction are pillar portions 3c. The column 3c is
b, axial portions 3c1 extending continuously in the axial direction, respectively.
And an inclined portion 3c2 extending obliquely from the axial portion 3c1, and an inner diameter portion 3c3 connecting the inclined portions 3c2 on both sides in the axial direction on the inner diameter side. In each pocket 3a, the circumferential dimension between the opposed inner diameter portions 3c3 is smaller than the diameter of the needle roller 2, so that the inner diameter portion 3c3 functions as a roller stopper. When the bearing rotates, the inclined portion 3c2 comes into contact with the rolling surface of the needle roller 2 on a pitch circle.

The retainer 3 is, for example, pressed from a thin SPC steel plate (forming a basic sectional shape) → punching out the pocket 3a → welding both ends (W portion shown in FIG. 2) → heat treatment (nitrocarburizing treatment) → barrel Through the process of processing, the form shown in FIG. 2 is completed. The surface roughness of the inner diameter surface of the cage 3 completed in this way (the inner diameter surface of the inner diameter portion 3c3) is 1.0 μm.
mRa or less.

As shown in FIG. 1, in this embodiment, a roller guide is adopted as a guide type of the retainer 3. Therefore, when the bearing rotates, the retainer 3 is guided by the needle rollers 2 and does not come into contact with the outer peripheral surface of the rotary shaft 10 by design. However, the inner diameter of the retainer 3 is In some cases, it may come into contact with the outer peripheral surface of the cable 10. However, since the inner surface of the retainer 3 has a surface roughness of 1.0 μm Ra or less, uneven contact hardly occurs at the contact portion even when the contact between them occurs.

In the embodiment shown in FIG. 3, the flange 1c '(the flange on the side to be bent) at one end of the outer ring 1 opens with a taper angle θ1 toward the outside of the bearing, and A tapered portion 1d is provided on the outer diameter surface of one end of the outer ring 1 with a taper angle gradually decreasing toward the outside of the bearing with a taper angle θ2. The taper angle θ1 and the taper angle θ2 are, for example, about 5 °.

By forming the flange portion 1c 'of the outer race 1 into the tapered shape as described above, the flowability of the lubricant into the bearing can be increased. Also, by providing the tapered portion 1d as described above on the outer diameter surface at one end of the outer ring 1, it is easy to secure coaxiality when the bearing is pressed into the fixed-side member (13b), and to fix the bearing. When the side member (13b) is formed of a soft material such as an aluminum material, there is no need to worry about damaging the fixed side member (13B) during the press-fitting operation.
The flange 1b at the other end of the outer ring 1 (the flange on the side where deep drawing is performed) may have the same tapered shape as described above, and the outer diameter surface at the other end of the outer ring 1 may also be formed. A tapered portion similar to the above may be provided.

The above-mentioned flange portion 1c 'and tapered portion 1d
Can be formed simultaneously using a jig 5 as shown in FIG. 4, for example. The jig 5 is provided with a bottom wall 5a having a taper angle θ1 and a peripheral wall 5b having a taper angle θ2, and the outer ring 1 (the needle roller 2 and the retainer 3 are incorporated) or a jig. When one end 1e (partially annealed) of the outer ring 1 is pushed into the jig 5 while rotating the jig 5, the one end 1e is moved from the peripheral wall 5b of the jig 5 to the bottom wall. 5c guides and bends, and the flange part 1c 'and the taper part 1d are formed simultaneously.

The present invention can be similarly applied to a shaft guide type needle roller bearing, and the structure of a swash plate type compressor incorporated therein is as shown in FIGS. 5, 6, and 7. Not limited.

[0029]

The present invention has the following effects.

(1) The inner surface of the cage has a surface roughness of 1.0
By setting the diameter to not more than μmRa, the aggressiveness of the outer peripheral surface of the rotating shaft is reduced, the uneven wear of the outer peripheral surface of the rotating shaft is suppressed, and the frictional force of the contact portion is reduced. Uneven wear of itself is also suppressed.

(2) The surface roughness of the raceway surface of the outer ring is set to 0.63
By ensuring that it is not more than μmRa, an appropriate oil film is formed at the contact portion between the raceway surface of the outer ring and the rolling surface of the needle roller, and damage such as peeling and smearing of the raceway surface and the rolling surface is prevented. Can be.

(3) Inward flanges are provided at both ends of the outer ring,
In addition, since at least one of the flanges has a tapered shape that opens toward the outside of the bearing, the flowability of the lubricant into the bearing can be increased.

(4) At least one of the two ends of the outer diameter surface of the outer ring is provided with a tapered portion whose diameter is gradually reduced toward the outer side of the bearing, thereby ensuring coaxiality when the bearing is pressed into the fixed side member. When the fixed-side member is formed of a soft material such as an aluminum material, the fear of damaging the fixed-side member during the press-fitting operation can be eliminated.

(5) As a result of extending the life of the needle roller bearing, the suction and compression operations of the swash plate type compressor are stably performed over a long period of time, and the reliability thereof is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a shell-type needle roller bearing according to an embodiment.

FIG. 2 is a sectional view of a cage.

FIG. 3 is a partial sectional view showing a shell-type needle roller bearing according to another embodiment.

FIG. 4 is a cross-sectional view showing an embodiment in which a tapered flange portion and a tapered portion are formed.

FIG. 5 is a cross-sectional view showing one configuration example of a swash plate compressor.

FIG. 6 is a cross-sectional view showing one configuration example of a swash plate type compressor.

FIG. 7 is a cross-sectional view showing one configuration example of a swash plate type compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer ring 2 Needle roller 3 Cage 10 Rotary shaft 13b Fixed side member

Claims (6)

[Claims] 1. A swash plate type compressor in which a piston is reciprocally slid in an axial direction in a cylinder by a rotating operation of a swash plate provided on a rotating shaft, and the rotating shaft is supported in a radial direction with respect to a fixed member. A needle roller bearing, comprising: an outer ring fixed to the fixed member; a plurality of needle rollers rotatably interposed between a raceway surface of the outer ring and an outer peripheral surface of the rotary shaft; and a needle roller. A needle roller bearing for a swash plate compressor, comprising: a cage made of a thin steel plate which is held at a predetermined circumferential interval; and wherein a surface roughness of an inner surface of the cage is 1.0 μmRa or less. 2. A weld holding device in which the cage is formed into a required cross-sectional shape and both ends of a flat thin steel plate formed with a plurality of pockets for accommodating needle rollers are welded to each other to form an annular body. The needle roller bearing for a swash plate type compressor according to claim 1, which is a compressor. 3. The needle roller bearing for a swash plate compressor according to claim 1, wherein said outer ring is a shell-type outer ring made of a thin steel plate. 4. The surface roughness of the raceway surface of the outer ring is 0.63.
4. The needle roller bearing for a swash plate type compressor according to claim 3, wherein the diameter is not more than μmRa. 5. The outer ring has an inward flange at both ends,
4. The needle roller bearing for a swash plate compressor according to claim 3, wherein at least one of the flanges has a tapered shape that opens toward the outside of the bearing. 6. The needle roller bearing for a swash plate compressor according to claim 3, wherein a tapered portion whose diameter is gradually reduced toward the outside of the bearing is provided on at least one of both ends of the outer diameter surface of the outer ring.