JP2003172339A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems of a vehicular alternator rolling bearing used under a harsh environment, wherein self-heating of a bearing is increased, seizure is often occurred, and life is short, due to giving priority to the performance of rolling fatigue life by setting the minimum value of a remaining clearance of the bearing slightly negative. <P>SOLUTION: In this rolling bearing lubricated by grease and used for an alternator, a remaining clearance is set to be not less than 15 μm. Therefore, self-heating is decreased, and a life of the rolling bearing can be extended. By suppressing heating in such a way, a life of grease filled in the bearing can be improved, and the life of the rolling bearing for the alternator can also be extended in such a point. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing for an electric vehicle accessory and, more particularly, to a rolling bearing suitable for an alternator bearing whose temperature and speed are increasing. . 2. Description of the Related Art In recent years, as automobiles have become smaller and lighter, engine accessories have also been required to be smaller and lighter and to have higher performance and higher output. Therefore, when the engine is running,
For example, a high vibration caused by high-speed rotation and a high load of 4 G to 20 G due to gravitational acceleration simultaneously act on a bearing for an alternator via a belt. In addition, the usage environment often becomes high temperature, and it is used in a severe environment. [0003] As described above, in a rolling bearing for an alternator used in a severe environment, grease is sealed inside and used. The minimum clearance is set slightly negative to give priority to rolling fatigue life. [0004] As described above, in a rolling bearing used in a severe environment, similarly to the conventional rolling bearing, the minimum value of the residual clearance is set to a slightly minus value to reduce the rolling fatigue. When the life performance is prioritized, self-heating of the bearing increases, seizure occurs frequently, and the life is shortened at that point. Accordingly, it is a primary object of the present invention to provide a rolling bearing suitable for an alternator, in which the life can be extended by appropriately setting the residual clearance. [0006] In order to solve the above-mentioned problems, the present invention provides a rolling bearing lubricated with grease and used for an alternator, wherein a residual clearance is set to 15 µm or more. It is what it was. By setting the residual clearance of the rolling bearing for an alternator in this way, self-heating of the bearing can be suppressed and the seizure life can be improved. Embodiments of the present invention will be described with reference to the drawings. Various types of alternator rolling bearings to which the present invention is applied have been conventionally proposed and used. Among them, FIG. 3 proposes that the alternator drive shaft is rotated by an engine, which is proposed by the present applicant. Of the power transmission device 1 provided with a driving pulley for the power transmission. In the power transmission device 1, a sleeve 3 provided with an internal thread 2 screwed to a male thread of a drive shaft of an alternator (not shown) is provided on the inner periphery of a center hole, and a pulley which rotates by rotating a belt driven by a crankshaft of an engine. 4, one-way clutch 5 and radial bearings 6, 7 on both sides thereof.
And are arranged. In this embodiment, the one-way clutch 5
A roller 10 is disposed between an outer ring 8 for a clutch, which is fixed in a pulley 4 and has a cam surface on the inner periphery, and an inner ring 9 for a clutch, fixed on the outer periphery of the sleeve 3. And a spring (not shown) for urging in one direction. The radial bearings 6 and 7 as support bearings rotatably support the sleeve 3 and the pulley 4. With this configuration, the driving force is transmitted by locking the load torque generated during driving by the clutch, and when the engine speed fluctuations and minute angular speed fluctuations occur, the one-way clutch 5 overruns. This shuts off power transmission. This mechanism prevents phenomena such as slippage and squeal of the belt, and improves the life of the belt. As a bearing used in the above-described power transmission device, for example, a bearing shown in an enlarged view in FIG. 4 is used. In this rolling bearing, the minimum value of the residual clearance is set slightly negative to give priority to the performance of the rolling fatigue life. That is, the rolling bearing 21 is
Is press-fitted into a housing 28 fixed to the outside,
The rolling element 24 is held by the retainer 25 so as to roll between the raceway surface 30 of the outer ring 22 as a fixed wheel and the raceway surface 31 of the inner ring 23 as a rotating wheel. A rolling element 24 and a retainer 25 are provided between the outer ring 22 and the inner ring 23.
Seals 26 are disposed on both sides of the seal, and a grease 29 is sealed in the inside to prevent foreign matter from entering from outside. In such alternator bearings, as described above, as the size and weight of automobiles are reduced in recent years, engine accessories are also required to be reduced in size and weight and to have high performance and high output. At times, high vibration caused by high-speed rotation and a high load of 4 G to 20 G due to gravitational acceleration simultaneously act on this bearing via the belt. In addition, the usage environment is often high temperature, and since it is arranged outside the vehicle, it is used in a severe environment. As described above, in a rolling bearing for an alternator filled with grease used in a harsh environment, the self-heating of the bearing was conventionally large, seizure occurred frequently, and the life was short. As a result of repeated intensive studies and repeated experiments to elucidate the cause, the major cause was that the minimum value of the residual clearance was set slightly negative in the conventional rolling bearing, giving priority to the performance of rolling fatigue life. In order to obtain an appropriate residual clearance, an experiment as described later was performed to obtain an appropriate residual clearance value. In the experiment, the bearing size was J
An experiment was performed using a bearing having an IS nominal number of 6303, urea grease sealed as grease, and a bearing temperature set at 180 ° C. In the experiment, as shown in FIG. 1, the radial clearance was gradually increased from 0, and data on a life ratio when the clearance was 0, that is, life ratio data on the clearance 0 was obtained. As a result, when the radial clearance, that is, the residual clearance is set to 15 μm or more, at least the clearance becomes zero.
It was found that the service life was at least twice as long as that at the time. In addition, as a grease, a thickener: diurea C, base oil; ether-based synthetic oil, base oil viscosity: 40 ° C .;
0, mm ² / sec 100 ° C .; 13, environmental load substance;
No rust preventive agent; small, mixed stabilizing agent; 282 can also be used. Further, as shown in FIG. 2, the radial clearance was gradually increased from 0, and data was obtained as the ratio of the bearing temperature to the ambient temperature at that time. As a result, it was found that the radial bearing clearance, that is, the residual clearance, decreased rapidly up to 15 μm, and thereafter decreased gradually. From these experimental results, it was found that the residual clearance was 15
It was found that it is preferable to set the thickness to at least μm. By setting such a value, the self-heating of the bearing can be reduced, the seizure life can be improved, and a long-life rolling bearing can be obtained. Further, by suppressing the heat generation in this way, it is possible to improve the life of the grease sealed in the bearing. The present invention is configured as described above.
By appropriately setting the residual clearance, self-heating of the bearing can be reduced, the seizure life can be improved, and a long-life rolling bearing can be obtained. In addition, by suppressing heat generation in this way, it is possible to improve the life of grease sealed in the bearing, and in this aspect, it is possible to prolong the life of the rolling bearing for the alternator.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing experimental data as a basis for obtaining a numerical value of a residual clearance according to the present invention, and particularly a graph showing a bearing life ratio due to a difference in radial clearance. FIG. 2 is a graph showing experimental data as a basis for obtaining a numerical value of a residual clearance according to the present invention, and in particular, is a graph showing a bearing temperature increase ratio due to a difference in radial clearance. FIG. 3 is a cross-sectional view showing an example of a rolling bearing for an alternator to which the present invention is applied. FIG. 4 is an enlarged sectional view of the rolling bearing. [Description of Signs] 1 Power transmission device 2 Female screw 3 Sleeve 4 Pulley 5 One-way clutch 6, 7 Radial bearing 8 Clutch outer ring 9 Clutch inner ring 10 Roller 11 Clutch retainer

Claims (1)

Claims 1. A rolling bearing lubricated with grease and used for an alternator, wherein a residual clearance is set to 15 µm or more.