JP2003287035A - Thrust needle bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thrust needle bearing wherein long longevity is secured even when a lubricating condition is bad. <P>SOLUTION: To abrasion resistance is improved and to the long longevity of the thrust needle bearing 10 is secured as surface roughness of raceway surfaces 11, 12 on which a roller 13 rolls is made 0.4 μm or less measured by a cutting level differential Rδc. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thrust needle bearing suitable for use in a car air conditioner compressor or the like.

[0002]

2. Description of the Related Art A variable capacity compressor is known as one type of car air conditioner compressor. Generally, in a variable displacement compressor, a drive shaft is rotatably fitted in a housing, a swash plate is connected to the drive shaft in a variable inclination angle, and a wobble plate slides on the swash plate. It is installed freely. A thrust bearing is arranged between the swash plate and the wobble plate. Wobble board,
One ends of the plurality of piston rods are attached at equal intervals in the circumferential direction, and the other ends of the piston rods are connected to the piston. The piston is provided so as to slide inside a cylinder provided in the housing, and compresses and discharges the refrigerant gas flowing into the bore of the cylinder. In other words, when the swash plate rotates, the wobble plate
A so-called rasping operation is performed, and the piston is reciprocated in the axial direction via the piston rod to compress and discharge the refrigerant gas.

[0003]

By the way, since the drive shaft receives a large force through the swash plate during operation of the car air-conditioning compressor, a thrust bearing for supporting the drive shaft in the thrust direction with respect to the housing is required. Becomes However, since the thrust bearing is arranged on the pulley unit side that is connected to the drive shaft and receives the rotation amount from the belt, it is located far from the supply source of the lubricating oil that is supplied in the form of mist, and therefore, There is a problem that the oil film formation between the rolling elements and the raceway surface becomes worse. If the thrust bearing is operated under such a bad lubrication condition, there is a possibility that the raceway raceway surface may be prematurely worn or the like, which causes a problem such as abnormal noise.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a thrust needle bearing capable of ensuring a long life even if the lubrication condition is bad.

[0005]

A thrust needle bearing of the present invention has a race raceway surface and a rolling element rolling on the race raceway surface, and the surface roughness of the race raceway surface is
The cutting level difference Rδc is set to 0.4 μm or less.

[0006]

In the conventional thrust needle bearing, the arithmetic mean roughness Ra defined as the surface roughness of the raceway surface is
(Or the maximum height Ry or the ten-point average roughness Rz) is positioned as an important factor that determines the life of the thrust needle bearing, and the material and processing accuracy are improved so as to improve the surface roughness. Was being done.

However, even with a thrust needle bearing in which the roughness of the raceway surface is kept within the design tolerance by the arithmetic mean roughness Ra, etc., it is generally considered that the lubricating condition is bad under high load and low speed rotation, for example, for car air conditioners. It has been found that premature wear may occur when used to receive the thrust force of the compressor drive shaft. However, in order to further improve the values of the arithmetic mean roughness Ra of the raceway surface,
This is not possible with normal processing, and special processing that requires time and labor such as grinding and superfinishing is required, which leads to an increase in cost.

On the other hand, the present inventors are erroneous in the conventional recognition that the raceway surface cannot be processed unless it is ground or the like, and such misconception is caused by the arithmetic mean roughness Ra.
I thought that it might be because the roughness of the raceway surface is regulated by etc. Furthermore, the present inventors have paid attention to the surface roughness flatness of the raceway surface, and have taken note of the cutting level difference Rδc (80% −3).
%) Is 0.4 μm or less, the wear resistance of the raceway surface can be improved without improving the arithmetic mean roughness Ra, etc., and moreover, ordinary processing is sufficient, so low cost is achieved. It was deduced that it is possible to provide various thrust needle bearings based on the results of the wear test described later.

Here, the cutting level difference Rδc means the load length rate tp (C
o) and the cutting height excluding the load length rate tp (Cn) of the oil sump portion, which is (tp (Co) -tp (C
n)). This is also referred to as a plateau rate Hp.
Here, the load length rate tp (Co) for the initial wear in the load curve of the surface roughness is 3% as an empirical value, and the load length rate tp (Cn) of the oil sump portion is the same as 80. % Is used, but not limited to this.

The cutting level difference Rδc will be specifically described. It is assumed that the surface to be measured is actually measured and a roughness curve (referred to as an extraction curve) as shown in FIG. 5 is obtained. Such an extraction curve is cut out with a certain reference length L, and the length of the cut portion of the surface cut by a straight line parallel to the average line and located a predetermined distance (called a cutting level C) below the maximum value The sum expressed as a percentage of the total length L is called a load length ratio tp, which can be expressed by the following formula. tp = (100 / L) Σbi (%) (i = 1 to N) (1)

Further, a relation between all the cutting levels C (%, which can also be expressed by μm) in the extraction curve and the load length tp (%) at the cutting level is called a load curve. Is shown in FIG. In the load curve, the load length ratio tp (Co) after the specified initial wear
(%) And the load length ratio tp (Cn) (%) after long-term wear
The difference between the cutting heights of and is called the cutting level difference Rδc, that is, (tp (Co) −tp (Cn)). The range of the cutting level difference Rδc is called a plateau, and the flatter and longer the plateau, the more improved the wear resistance. The range of 0% -Co is
It is an initial worn portion, and the range of Cn-100% corresponds to an oil pool.

Such a thrust needle bearing is suitable for use in a car air conditioner compressor.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a car air conditioner compressor using a thrust needle bearing according to the present embodiment. FIG. 2 is an enlarged cross-sectional view of the thrust needle bearing.

In FIG. 1, a variable capacity compressor, which is a compressor for a car air conditioner, is a housing 1
The drive shaft 2 is rotatably fitted to the swash plate 3, the swash plate 3 is connected to the drive shaft 2 in a variable inclination angle, and the wobble plate 4 is slidably attached to the swash plate 3. A thrust bearing 5 is arranged between the swash plate 3 and the wobble plate 4. One end of a plurality of piston rods 6 is attached to the wobble plate 4 at equal intervals in the circumferential direction, and the other end of the piston rod 6 is connected to a piston 7. This piston 7
Is provided so as to slide inside a cylinder 1a provided in the housing 1, and the refrigerant gas flowing into the bore of the cylinder 1a is compressed and discharged.
The right end of the drive shaft 2 in FIG. 1 is connected to a pulley 8 via a clutch mechanism CM, and a thrust plate 9 is press-fitted to the pulley 8 side outer periphery of the drive shaft 2 so as to rotate integrally,
A thrust needle bearing 10 is arranged between the thrust plate 9 and the housing 1.

In FIG. 2, the thrust needle bearing 10
Is a race 11 attached to the thrust plate 9, a race 12 attached to the housing 1, and both races 1
It is composed of a plurality of rollers 13 which are rolling elements arranged between 1 and 12 so as to be rollable, and a cage 14 which holds the rollers 13 at equal intervals in the circumferential direction.

When the clutch mechanism CM is turned on, the operation of the car air conditioner compressor is started. In this case, when the pulley 8 is driven by a belt (not shown), the drive shaft 2
When the swash plate 3 is rotated, the wobble plate 4 makes a so-called rasping motion, causing the piston 7 to reciprocate in the axial direction via the piston rod 6.
The refrigerant gas is compressed and discharged.

At this time, from the piston 7 to the drive shaft 2,
The compression force of the refrigerant gas is transmitted as a thrust force, and the thrust needle bearing 10 supports the thrust force between the thrust plate 9 and the housing 1. The blow-by gas generated by the operation of the piston 7 flows in the direction of the arrow in FIG. 1, and each part is lubricated using the mist-like lubricating oil contained in the blow-by gas. Since 10 is located away from the piston 7, the lubrication condition is severe. On the other hand, the thrust needle bearing 10 according to the present embodiment secures a long life by setting the cutting level difference Rδc to an appropriate value.

The wear test conducted by the present inventors will be described below. Test conditions (1) Test bearing size (inner diameter x outer diameter x height): φ4
0 × φ60 × 5 (mm) (2) Axial load (thrust force): 3,500
N (3) Rotational speed: 1000min ^-1 (4) Test time: 24h

Table 1 shows the results of the bearing test in which the arithmetic mean roughness Ra of the raceway surface is equal but the cutting level difference Rδc is changed in the wear test according to the above conditions. FIG. 3 is a roughness curve obtained by measurement before the test on the race raceway surface of the numbered bearing, and FIG. 4 is a roughness curve obtained by measurement before the test on the raceway surface of the numbered bearing. It is a curve.

[Table 1]

According to the results of this test, even if the arithmetic mean roughness Ra of the raceway surface is 0.1, the cutting level difference Rδ is equal.
In bearings with c of 0.6 μm and 0.5 μm, wear occurred on the raceway surface and the rollers. On the other hand, with respect to the bearings having the cutting level difference Rδc of 0.4 μm and 0.2 μm, neither wear was observed on the raceway surface or the rollers. To analyze this, the cutting level difference Rδc (80% -3%)
Is 0.4 μm or less, even if the arithmetic mean roughness Ra is
Even if the same is applied, it is considered that the contact area of the rollers on the raceway surface becomes large, so that the contact surface pressure can be reduced and the wear resistance can be improved.

Although the present invention has been described above with reference to the exemplary embodiments, the present invention is not limited to the above-described exemplary embodiments, and it goes without saying that modifications and improvements can be made within the scope of the invention. Is. For example, the thrust needle bearing according to the present invention can be used not only in the compressor for car air conditioners but also in various automobiles, industrial machines and the like.

[0022]

The thrust needle bearing of the present invention has a raceway surface and rolling elements that roll on the raceway surface. The surface roughness of the raceway surface is determined by the cutting level difference R.
Since δc is 0.4 μm or less, wear resistance is improved,
A long life can be secured.

[Brief description of drawings]

FIG. 1 is a sectional view of a car air conditioner compressor using a thrust needle bearing according to the present embodiment.

FIG. 2 is an enlarged sectional view of a thrust needle bearing.

FIG. 3 is a roughness curve obtained by measurement before a test on a raceway surface of a bearing having a number.

FIG. 4 is a roughness curve obtained by measurement before a test on a raceway surface of a bearing having a number.

FIG. 5 is a diagram for explaining a cutting level difference Rδc.

[Explanation of symbols]

1 housing 2 drive shaft 3 swash plate 4 wobble board 6 piston rod 7 pistons 9 Thrust plate 10 Thrust needle bearing

Claims (2)

[Claims] 1. A raceway raceway surface and rolling elements rolling on the raceway raceway surface are provided, and a surface roughness of the raceway raceway surface is set to 0.4 μm or less at a cutting level difference Rδc. And thrust needle bearing. 2. The thrust needle bearing according to claim 1, which is used in a compressor for a car air conditioner.