JP2002333030A - Thrust needle roller bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thrust needle roller bearing for preventing the skewing of a needle roller and improving its life. SOLUTION: The thrust needle roller bearing 1 comprises a pair of thrust races 11, 12 for contacting the needle roller 14, the thrust race 12 on the side of a good lubricating condition having a surface roughness set to be larger than that of the thrust race 11 on the side of a bad lubricating condition depending on a difference in actual lubricating condition.

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 in which needle rollers are disposed between a pair of thrust traces mounted on opposing surfaces of two relatively rotating objects that face each other in the rotation axis direction. The present invention relates to an improvement for preventing a needle roller from skewing and improving a bearing life.

[0002]

2. Description of the Related Art In a motor vehicle, general industrial equipment, or the like, a thrust bearing for receiving a thrust load of a rotating body has a needle-like shape between a pair of thrust traces mounted on opposing surfaces of two relatively rotating objects facing each other in the direction of the rotation axis. Thrust needle roller bearings in which rollers are arranged have become widespread.

[0003] The above thrust needle roller bearing usually supplies lubricating oil to a gap between a pair of thrust traces and forms a lubricating oil film on a contact surface of the needle rollers, thereby forming a gap between the rollers and the thrust trace. And at the same time suppress heat generation due to frictional heat and the like. In the case of a conventional thrust needle roller bearing, a pair of thrust traces that come into contact with the needle rollers have a common surface roughness regardless of the use conditions of the bearing or the difference in the outer form of each thrust trace. I have.
In general, the surface roughness of each thrust trace is
It is about 0.1 Ra.

[0004]

However, in the actual use situation of the thrust needle roller bearing, the difference in the outer shape of each thrust trace, the shape of the facing surface of two objects equipped with the thrust trace, and further, The lubricating oil flow in the gap between the pair of thrust traces (ie, the gap around the needle roller) can be biased due to the positional relationship between the lubricating oil supply and discharge ports, etc.
As a result, there is a difference in the lubrication state between the respective thrust traces, and one thrust trace can obtain a good lubrication state, but the other thrust trace often has a poor lubrication state.

The lubricating oil film is formed well on the contact surface of the thrust trace on the side with good lubrication, and the coefficient of sliding friction on the needle rollers is small, but the contact surface of the thrust trace on the side with poor lubrication is good. In this case, a lubricating oil film cannot be formed satisfactorily, and the coefficient of sliding friction against rollers increases. Then, the difference in the coefficient of sliding friction generated between the two thrust traces causes skew of the rollers, and this skew causes the oil film to be cut off on the contact surface, resulting in a problem that the life of the bearing is shortened.

As a method for preventing the occurrence of such skew of the needle rollers, it is conceivable to manage the lubrication method so that the lubrication state of the pair of thrust traces becomes equal. However, in that case, many improvements are required for the equipment, such as devising the arrangement of the supply and discharge ports of the lubricating oil, dispersing the supply and discharge ports, and detecting the distribution of the lubricating oil pressure between the pair of thrust traces. Therefore, practical application is difficult.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thrust needle roller bearing capable of preventing occurrence of skew and extending the life of the bearing.

[0008]

According to the present invention, there is provided a thrust needle roller bearing according to the present invention, which comprises a pair of thrust traces mounted on opposing surfaces of two relatively rotating objects opposed to each other in the direction of the rotation axis. In a thrust needle roller bearing in which the needle rollers are arranged at different positions, the lubrication state is determined according to the difference in the lubrication state of each thrust trace so that the substantial sliding friction coefficient of the pair of thrust traces with respect to the needle rollers is equal. The surface roughness of the thrust trace on the good side is set larger than the surface roughness of the thrust trace on the poor lubrication state.

The actual coefficient of sliding friction between the thrust trace and the needle roller depends on the surface roughness of the contact surface of the thrust trace and the lubrication condition on the contact surface. Therefore, as described above, by providing a difference in the surface roughness of the pair of thrust traces in contact with the needle rollers so as to compensate for the difference in the lubrication state, substantial sliding friction between the pair of thrust traces is achieved. The coefficients can be made uniform, and the skew of the needle rollers can be prevented by eliminating the difference in the coefficient of sliding friction that causes skew. In addition, since the countermeasure for this is simply to make the surface roughness of each thrust trace different, the countermeasure cost can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a thrust needle roller bearing according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing one embodiment of a thrust needle roller bearing according to the present invention.

The thrust needle roller bearing 1 of this embodiment has a pair of thrust thrusters mounted on opposing surfaces 3a, 5a of the two objects 3, 5 which rotate relative to each other around a rotation axis 7 in the direction of the rotation axis. Races 11 and 12 and a plurality of needle rollers 14 provided between these thrust races 11 and 12
And a retainer 16 for positioning and holding the plurality of needle rollers 14 at predetermined intervals around the rotation axis 7 between the pair of thrust traces 11 and 12.

One object 5 has a shaft 5 along a rotation axis 7.
b, and a flange portion 5c connected to the end of the shaft portion 5b. The surface of the flange portion 5c is a mounting surface of the thrust trace 12. Also, the other object 3 is
A bulging portion 3c having an opposing surface 3a on which the thrust trace 11 is mounted is provided on the outer periphery of the cylindrical portion 3b that fits loosely on the shaft portion 5b of the object 5. One of these two objects 3 and 5 is driven to rotate about the rotation axis 7 and the other is non-rotating and supports a thrust load from the rotating side via the thrust needle roller bearing 1.

The lubricating oil is supplied to the thrust needle roller bearing 1 through a gap 9 between the two objects 3 and 5 from the center side to the outer diameter side as shown by arrows A and B in the figure.

The thrust trace 12 mounted on the object 5 is a simple donut-shaped flat plate that is in close contact with the facing surface 5a.
However, the thrust trace 11 attached to the object 3 has a structure in which a flange portion 11b protruding in the axial direction extends from an inner peripheral edge of a donut-shaped flat plate portion 11a in close contact with the facing surface 3a.

The retainer 16 includes a pair of retaining plates 16a, 16a.
b. A pair of holding plates 16a, 16b
Is a press-formed product of a metal plate, and a pair of thrust traces 1
At the same time as having a ring shape orbiting the space sandwiched between the needle rollers 1 and 12, pockets for accommodating and holding the needle rollers 14 are formed at regular intervals in the circumferential direction. Each of the holding plates 16a and 16b has a required rigidity by bending the flange portions 17 and 18 at the inner edge and the outer edge.

In the case of this embodiment, the lubricating oil flowing between the pair of thrust traces 11 and 12 from the gap 9 on the center side of the two objects 3 and 5 protrudes from the cylindrical portion 3b of the object 3 and the thrust trace 11 Of the thrust trace 11 and the flange portions 17 and 18 of the cage 16 are close to each other, so that the opening on the contact surface side of the thrust trace 11 is small.
The lubrication state on the first side is worse than the lubrication state on the thrust trace 12 side. In the case of the present embodiment, the supply amount of the lubricating oil to the thrust needle roller bearing 1 is such that the lubrication state on the thrust trace 12 side is good and the lubrication state on the thrust trace 11 side is slightly deteriorated. Set as appropriate.

In other words, in consideration of the difference in the lubrication state between the thrust traces 11 and 12, the present embodiment provides:
The surface roughness of the thrust trace 12 on the good lubrication state is reduced so that the pair of thrust traces 11 and 12 have substantially the same coefficient of sliding friction with respect to the needle rollers 14. Is set to be larger than the surface roughness.

Usually, in a thrust needle roller bearing, the actual coefficient of sliding friction between each thrust trace and the needle roller depends on the surface roughness of the contact surface of each thrust trace and the lubrication state on the contact surface. It changes according to. Therefore, as in the above-described embodiment, the pair of thrust traces 11 and 12 that come into contact with the needle rollers 14 are adjusted so as to compensate for the difference in the lubrication state.
When the surface roughness is different, the substantial coefficient of sliding friction between the pair of thrust traces 11 and 12 can be made uniform, and thus the difference in the coefficient of sliding friction that causes skew can be eliminated. The skew of the needle rollers 14 can be prevented. In addition, since the countermeasure for this is simply to make the surface roughness of each thrust trace different, the countermeasure cost can be reduced. Therefore, the occurrence of skew can be prevented at low cost, and the bearing life can be improved.

The above pair of thrust traces 11,
The specific outer shape of the twelfth, the shape of the two objects 3 and 5, the supply direction of the lubricating oil, and the like are not limited to the above-described embodiment, and the design can be appropriately changed without departing from the spirit of the present invention. Needless to say, there is.

[0020]

According to the thrust needle roller bearing of the present invention, by providing a difference in the surface roughness of a pair of thrust traces in contact with the needle rollers so as to compensate for the difference in the lubrication state, the thrust trace is provided. It is possible to make the substantial sliding friction coefficients uniform between them, and to eliminate the difference in the sliding friction coefficient that causes skew, thereby preventing the needle rollers from skewing. In addition, since the countermeasure for this is simply to make the surface roughness of each thrust trace different, the countermeasure cost can be reduced. Therefore, the occurrence of skew can be prevented at low cost, and the bearing life can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of a thrust needle roller bearing according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thrust needle roller bearing 3,5 Object 3a, 5a Opposed surface 7 Rotation axis 11,12 A pair of thrust trace 11b Flange part 14 Needle roller 16 Cage 17,18 Flange part

Claims (1)

[Claims] 1. A thrust needle roller bearing in which a needle roller is disposed between a pair of thrust traces mounted on opposing surfaces of two objects that rotate relative to each other in the direction of the rotation axis, wherein the needle rollers of the pair of thrust traces are provided. In accordance with the difference in the lubrication state of each thrust trace, the surface roughness of the thrust trace with the better lubrication state is changed to the surface of the thrust trace with the poorer lubrication state so that the substantial sliding friction coefficient with respect to Thrust needle roller bearings characterized in that they are set larger than the roughness.