JP2000027870A - Alternator ball bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a large surface pressure based on an edge load from acting on the rolling surface of each ball by setting the curvature radiuses of the sectional forms of inner and outer ring raceway tracks to specified ratios to the diameter of the ball. SOLUTION: In an alternator ball bearing where the ratio D/d of the pitch circle diameter D of a plurality of balls 14 to the diameter (d) of each ball 14 is within the range of 3.0-5.0, the curvature radius r9a of an inner ring raceway track 9a is regulated within the range of 50.9-51.2% of the outer diameter (d) of the ball 14. Further, the curvature radius r11 of an outer ring raceway track 11 is regulated within the range of 53.0-53.7% of the outer diameter (d) of the ball 14 as in the past. The curvature radius r9a of the inner ring raceway track 9 is limited to a relatively larger value than in the past in this way, whereby the rolling surface of each ball 14 never runs out from the inner ring raceway track 9a even if each ball 14 is slightly displaced. Accordingly, the rolling fatigue life can be improved even in the use under a sever condition as a large vibration acts thereon with high rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The ball bearing for an alternator according to the present invention is used for rotatably supporting a rotor of an alternator, which is a generator for an automobile, with respect to a housing to which a stator is fixed.

[0002]

2. Description of the Related Art The structure of an alternator for generating electric power necessary for an automobile by using an engine for driving the automobile as a driving source is described in, for example, Japanese Patent Application Laid-Open No. 7-139550. FIG. 3 shows an alternator 1 described in this publication. The alternator 1 rotatably supports a rotating shaft 3 inside a housing 2 by a pair of ball bearings 4, 4. A rotor 5 and a commutator 6 are provided at an intermediate portion of the rotating shaft 3. A driven pulley 7 is fixed to a portion of the rotating shaft 3 protruding outside the housing 2 at one end (the right end in FIG. 3). Housing 2
Is fixed to an engine (not shown), and an endless belt (not shown) is wrapped around the driven pulley 7 to transmit the rotation of the crankshaft of the engine to the rotating shaft 3 via the endless belt. Further, a portion existing around the rotor 5 inside the housing 2 includes:
The stator 8 is fixed. The alternator 1 configured as described above rotates the rotating shaft 3 provided with the rotor 5 by the rotation of the engine, and generates an electromotive force in the stator 8 facing the rotor 5.

As a ball bearing 4 for an alternator for rotatably supporting a rotating shaft 3 on a housing 2 by using the alternator 1 as described above, generally, a deep groove as shown in FIG. Uses ball bearings. This ball bearing 4
Has an inner ring 10 having a deep groove type inner ring raceway 9 having an arcuate cross section on the outer peripheral surface and rotating at the time of use, and a deep groove outer ring raceway 11 having an arcuate cross section on the inner peripheral surface. And an outer ring 12 that does not rotate at times. And, the inner raceway 9
A plurality of balls 14 are rotatably provided between the outer ring raceway 11 and a plurality of balls 14 held in pockets provided in a retainer (not shown).

[0004] Incidentally, the inner ring raceway 9 and the radius of curvature r _9, r ₁₁ of the cross section of the outer raceway 11 is greater than the respective 50% of the diameter d of the balls _{14 (r 9, r 11>} 0.5d) Thus, the friction between the inner raceway 9 and the outer raceway 11 and the rolling surface of each ball 14 is reduced. Further, and significantly (r _11> r ₉₎ than the radius of curvature r ₉ of the inner ring raceway 9 radius of curvature r ₁₁ of the outer ring raceway 11. The reason for this is that the area of the contact ellipse existing in the contact portion between the rolling surface of each ball 14 and the inner raceway 9, the rolling surface of each ball 14 and the outer raceway 1
This is to prevent the area of the contact ellipse existing in the contact portion with the bearing member 1 from being largely different from each other, so that the rolling fatigue life between the inner raceway 9 and the outer raceway 11 does not greatly differ.

That is, since the shape of the outer raceway 11 in the circumferential direction is concave on the side of each ball 14, the contact ellipse of the contact portion between the outer raceway 11 and the rolling surface of each ball 14 is formed. The diameter in the circumferential direction increases. On the other hand, the shape of the inner ring raceway 9 in the circumferential direction is such that the contact ellipse of the contact portion between the inner ring raceway 9 and the rolling surface of each ball 14 is convex because the side of each ball 14 is convex. The diameter in the circumferential direction decreases. Therefore, when equal to the radius of curvature r _9, r ₁₁ of the cross section of the inner ring raceway 9 and the outer ring raceway 11, the contact ellipse existing in the contact portion between the rolling surface and the inner ring raceway 9 of the balls 14 Is considerably smaller than the area of the contact ellipse existing in the contact portion between the rolling surface of each ball 14 and the outer raceway 11, and the rolling fatigue life of the inner raceway 9 is longer than that of the outer raceway 11. It is considerably shorter than the life.

Therefore, conventionally, the radius of curvature r ₁₁ of the outer raceway 11 is made larger than the radius of curvature r ₉ of the inner raceway 9, and the contact between the outer raceway 11 and the rolling surface of each ball 14 is brought into contact. The diameter of the ellipse in the axial direction is reduced, and the diameter of the contact ellipse in the contact portion between the inner raceway 9 and the rolling surface of each ball 14 is increased in the axial direction of the ellipse. Is not generated. For example, the ratio D / d between the pitch circle diameter D of the plurality of balls 14 and the diameter d of each of the balls 14, which is a general ball bearing for an alternator for an automobile, which is an object of the present invention, is 3.0. If despite the range of 5.0, 53.0 to 53.7% of the diameter d of the balls 14 the radius of curvature r ₁₁ of the outer ring raceway 11 {r ₁₁ =
(0.53 to 0.537) d｝, and the radius of curvature r ₉ of the inner raceway 9 is 50.5 to 5 of the diameter d of each ball 14.
0.8% {r ₉ = (0.505 to 0.508) d} was set.

[0007]

The alternator ball bearing 4 is used under severe conditions such as high rotation and large vibration. Therefore, based on the existence of the bearing gap in the alternator ball bearing 4, the inner ring 10 and the outer ring 1
2 is relatively displaced in the axial direction, or
As shown exaggeratedly in FIG. 4, these inner ring 10 and outer ring 12
The operation may be performed in a state where the central axes of the inner ring 10 and the outer ring 12 are not coincident (the planes α and β perpendicular to the central axes of the inner ring 10 and the outer ring 12 form an angle θ other than 0). Then, when the alternator ball bearing 4 is operated in such a state, the rolling surface of each ball 14 may deviate from the inner raceway 9.

That is, as described above, the radius of curvature r ₉ of the cross section of the inner raceway ₉ is 50.5 to 5 times the diameter d of each ball 14.
Since the diameter d is 0.8%, which is close to the diameter d, even when each of the balls 14 is slightly displaced with respect to the inner raceway 9,
The rolling surface of each of the balls 14 comes off the inner raceway 9 and rides on the shoulder 13 at the edge of the inner raceway 9. When the ball 14 rides on the shoulder 13 in this manner, a large surface pressure based on edge load acts on the rolling surface of each of the balls 14 to significantly reduce the rolling fatigue life of the rolling surface. Not preferred. The present invention has been made in view of the above-described circumstances, and aims to improve the rolling fatigue life of an alternator ball bearing used under severe conditions.

[0009]

The ball bearing for an alternator of the present invention has an inner ring raceway having an arc-shaped concave cross section on the outer peripheral surface, similar to the above-described conventional alternator ball bearing, and rotates during use. And an outer ring having an outer raceway having a cross section concave in an inner peripheral surface and having an arc-shaped cross section, the outer raceway not rotating even during use, and a plurality of balls rotatably provided between the inner raceway and the outer raceway. . The ratio D / d of the pitch circle diameter D of the plurality of balls to the diameter d of each of the balls is 3.0 to 5.0.
In the range. In particular, in the alternator ball bearing of the present invention, the radius of curvature of the cross-sectional shape of the inner raceway is set to 50.9 to 51.2% of the diameter d of the ball, and the cross-sectional shape of the outer raceway is determined. The radius of curvature is 5 times the diameter d of the ball.
It is set to 3.0 to 53.7%.

[0010]

According to the alternator ball bearing of the present invention constructed as described above, the radius of curvature of the inner ring raceway is 50.9 to 51.2 of the diameter d of the ball, which is a large value as compared with the conventional art.
%, The rolling surface of each ball does not deviate from the inner ring raceway to the extent that each ball is slightly displaced with respect to the inner ring raceway, and the rolling surface is located at the edge of the inner ring raceway. It doesn't ride on existing shoulders. Therefore, even when the ball is used under severe conditions such as high rotation and large vibration is applied, a large surface pressure based on edge load is prevented from acting on the rolling surface of each of the balls. The rolling fatigue life of the rolling surface can be ensured.

[0011]

1 and 2 show an embodiment of the present invention. Ball bearing 4 for alternator of the present invention
a is an inner ring 10a which has an inner ring raceway 9a having an arcuate cross section on its outer peripheral surface and rotates during use, and an arcuate cross section is similar to the above-described conventional ball bearing 4 (FIGS. 3 to 5). Outer ring 12 having outer ring track 11 on the inner peripheral surface and not rotating during use
And a plurality of balls 14 rotatably provided between the inner raceway 9 and the outer raceway 11. In addition, each of these balls 14
Are held one by one in a pocket provided in a holder (not shown). Such an alternator ball bearing 4a is configured such that the inner ring 10a is connected to the rotating shaft 3 of the alternator 1.
(See FIG. 3), and the outer ring 12 is fixed to the housing 2 of the alternator 1
The rotor 5 of the alternator 1 is rotatably supported on the housing 2 to which the stator 8 is fixed by fixing the rotor 5 to the inside of the alternator 1 directly or through a member fixed to the housing 2 (see FIG. 3). . In the present invention, the pitch circle diameter D of the plurality of balls 14 and the diameter d of each ball 14
And the ratio D / d with respect to the alternator ball bearing 4 in the range of 3.0 to 5.0.

In particular, in the case of the alternator ball bearing of the present invention, the radius of curvature r _9a of the inner raceway 9a is set to 50.9 to 51.2% of the outer diameter d of the ball 14 ｛r _9a = (0.509). ~
0.512) d｝, and the radius of curvature r ₁₁ of the outer raceway 11 is set to 53.
_{0~53.7% {r 11 = (0.53~0.537} ) d}
The range is regulated.

According to the alternator ball bearing of the present invention configured as described above, the radius of curvature r _9a of the inner raceway 9 is determined by:
Since the value is set to 50.9 to 51.2% of the outer diameter of the ball 14, which is a relatively large value as compared with the related art, the inner ring raceway 9a
On the other hand, to the extent that the balls 14 are slightly displaced, the rolling surfaces of the balls 14 do not deviate from the inner raceway 9a. There is no running on part 13. Therefore, even when used under severe conditions such as high rotation and large vibrations are applied, a large surface pressure based on edge load is prevented from acting on the rolling surface of each ball 14, The rolling fatigue life of the rolling surface can be ensured.

Further, even if an assembling error (misalignment) occurs when assembling the ball bearing 4a to the alternator, the contact state between the inner raceway 9a and the rolling surface of each of the balls 14 is changed to a favorable state (rolling). (A state in which the surface does not contact the shoulder 13). Incidentally, less than 50.9% of the outside diameter d of the radius of curvature r _9a is the balls 14 of the inner ring raceway 9a (r _9a <
In the case of 0.509d), there is a possibility that the rolling surface of each of the balls 14 rides on the shoulder 13 in a use state normally considered for an alternator. On the contrary, if the radius of curvature r _9a of the inner ring raceway 9a exceeds 51.2% of the outer diameter d of the balls 14 (r _9a> 0.512d) is
The area of the contact portion between the inner raceway 9a and the rolling surface of each ball 14 becomes too small, and it becomes difficult to secure the rolling fatigue life of the inner raceway 9a. In other words, in the case of the present invention, the radius of curvature r _9a of the inner raceway 9a is restricted to the range of 50.9% to 51.2% of the outer diameter d of the ball 14, whereby each ball 14 This ensures both the securing of the rolling fatigue life of the rolling surface and the securing of the rolling fatigue life of the inner raceway 9a.

On the other hand, the radius of curvature r ₁₁ of the outer raceway 11 is originally 53.0 to 53.7% of the diameter d of each ball 14 which is relatively larger than the inner raceway 9.
Therefore, there is a low possibility that the rolling surface of each ball 14 rides on the shoulder 15 existing at the edge of the outer raceway 11. Furthermore, increasing the curvature radius r ₁₁ of the outer ring raceway 11 in this manner, to ensure the area of the contact portion between the outer ring raceway 11 and the rolling surface of the balls 14, outer ring raceway 11 and the rolling As described above, the rolling contact fatigue life of the moving surface can be ensured. As a result, the alternator ball bearing of the present invention sets the inner ring raceway 9a, the outer raceway 11 and the balls 14 by setting the radii of curvature _r9a , r11 of the inner raceway 9a and the outer raceway ₁₁ to appropriate ranges. The rolling fatigue life of the rolling surface can be secured, and the life of the ball bearing 4a as a whole can be secured. Incidentally, the present inventor described the present invention as a reference number 6203 (the inner ring inner diameter D _10a is 17 mm, and the outer ring outer diameter D ₁₂ is 4 mm).
When the test was performed on a deep groove ball bearing having a diameter of 0 mm and a width B of 12 mm), it was confirmed that the ball bearing had superior durability as compared with the conventional structure.

[0016]

Since the present invention is constructed and operates as described above, the rolling contact fatigue life of the alternator ball bearing used under severe conditions in terms of vibration and the like is secured and excellent durability is provided. It can contribute to the realization of an alternator.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing an example of an embodiment of the present invention in a neutral state.

FIG. 2 is a partial cross-sectional view showing a state in which a ball is displaced with respect to an inner ring, with an outer ring omitted.

FIG. 3 is a cross-sectional view showing an alternator incorporating an alternator ball bearing according to the present invention.

FIG. 4 is a partial cross-sectional view showing one example of a state in which the inner ring and the outer ring are relatively displaced in a state where their respective axes are not aligned with each other.

FIG. 5 is a partial cross-sectional view showing a state in which a ball is displaced with respect to an inner ring, with an outer ring omitted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Alternator 2 Housing 3 Rotating shaft 4, 4a Ball bearing 5 Rotor 6 Commutator 7 Follower pulley 8 Stator 9, 9a Inner ring track 10, 10a Inner ring 11 Outer ring track 12 Outer ring 13 Shoulder part 14 Ball 15 Shoulder part

Claims (1)

[Claims] 1. An inner ring which has an inner raceway having a cross section depressed in an arc shape on the outer peripheral surface and rotates during use, and an outer race which has an outer raceway having a cross section depressed in an arc shape on the inner peripheral surface and does not rotate during use. ,
A plurality of balls rotatably provided between the inner raceway and the outer raceway, wherein a ratio D / d of a pitch circle diameter D of the plurality of balls to a diameter d of each of the balls is 3; 0.0-5.0
In the alternator ball bearing according to the present invention, the radius of curvature of the cross-sectional shape of the inner raceway is set to 50.
9 to 51.2%, and the radius of curvature of the cross-sectional shape of the outer raceway is 53.0 to 53.7% of the diameter d of the ball.
Ball bearings for alternators, characterized in that: