Rotary machine having single row four contact point bearing

Details Rotary machine having single row four contact point bearing Rotary machine having single row four contact point bearing

1999-11-23

2001-06-12

Lorence, Richard M. (Department: 3681)

192 clutches and power-stop control

Clutches

Operators

C192S11000B, C384S516000

Reexamination Certificate

active

06244408

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
This Application is based on and incorporates herein by reference Japanese Patent Application No. Hei. 10-350308 filed on Dec. 9, 1998.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotary machine and an electromagnetic clutch suitable for use in a compressor of an automotive air conditioning system, and a belt transmission adjusting the driving belt tension of a vehicle.
2. Description of Related Art
FIG. 4
shows a conventional electromagnetic clutch
100
used for a compressor of an automotive air conditioner. The electromagnetic clutch
100
includes a pulley
101
, a rotor
102
, an electromagnetic coil
103
, an armature
104
and a hub
105
. The pulley
101
and the rotor
102
rotates by receiving a rotational force from a vehicle engine through a belt
110
, and the armature
104
is placed to face the rotor
102
with a predetermined slight gap therebetween. The armature
104
is connected to a compressor shaft
121
through the hub
105
. When the electromagnetic coil
103
is energized, the armature
104
couples to the rotor
102
, and the rotation of the rotor
102
is transmitted to the compressor shaft
121
through the armature
104
and the hub
105
.
A bearing
106
is provided between the inner periphery of the rotor
102
and a cylindrical boss portion
122
of the compressor
120
. The bearing
106
rotatably supports the rotor
102
.
In general, the bearing
106
, used in the electromagnetic clutch of the compressor, is a double row angular contact ball bearing. Such a bearing
106
includes an inner race
106
a
, an outer race
106
b
, and a plurality of balls
106
c
arranged in double rows between the inner and outer races
106
a
and
106
b
, and has a contact angle &agr;. Each ball
106
c
contacts both inner and outer races
106
a
,
106
b
at one point respectively. Here, in
FIG. 5
, numerals
201
-
208
denote the contact points between the balls
106
c
and the inner and outer races
106
a
,
106
b.
However, in the above described electromagnetic clutch, the bearing
106
creates unwanted noise. This bearing noise especially occurs when the rotation speed of the compressor
120
is low, the temperature around the compressor
120
is low, grease in the bearing
106
leaks, or the viscosity of the grease is low.
As shown in
FIG. 4
, an action line E of a tension D of the belt
110
axially diverts from the radial central line F of the bearing
106
. In the bearing
106
, slight gaps (about 40&mgr;) are provided between the balls
106
c
and the inner and outer races
106
a
,
106
b
in the radial direction. Thus, a moment caused by the tension D of the belt
110
makes the outer race
106
b
incline in the counter clockwise direction. Similarly, the pulley
101
and the rotor
102
are made to incline.
Here, as the balls
106
c
are arranged in double row, even when the outer race
106
b
inclines, the top ball
106
c
in the left row in
FIG. 5
contacts both inner and outer races
106
a
,
106
b
at the contact points
201
,
202
. Similarly, the bottom ball
106
c
in the right row contacts both inner and outer races
106
a
,
106
b
at the contact points
207
,
208
.
However, when the outer race
106
b
inclines in the counter clockwise direction in
FIG. 5
, gaps between the inner and outer races
106
a
and
106
b
expand at the lower left row and the upper right row. Thus, as shown in
FIG. 6
, gaps occur between the lower side ball
106
c
′ and the inner and outer races
106
,
106
b
at the left row, and the lower side ball
106
c
′ rotates in accordance with the outer race
106
b
rotating in an arrow G direction. As a result, the lower side ball
106
c
′ falls from the inner race
106
a
to the outer race
106
b
due to the gravity and centrifugal forces, and collides with the outer race
106
b
, thereby creating unwanted noise.
Additionally, as shown in
FIG. 7
, there arise gaps between the upper side ball
106
c
″ and the inner and outer races
106
a
at the right row. Thus, the upper side ball
106
c
″ falls due to gravity and collides with the inner race
16
a
, also creating unwanted noise.
When the vehicle engine operates at high rotation speed, the centrifugal force increases, so that the balls
106
c
always contact the outer race
106
b
. Thus, the noise caused by the collisions between the balls
106
c
and the races
106
a
,
106
b
is not generated. Therefore, the above described noise problem especially exists when the bearing
106
is used at a low rotation speed, or is used with a rotation source operating from a low rotation speed through a high rotation speed, such as on a vehicle engine.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a rotary machine, especially an electromagnetic clutch, being capable of preventing the noise caused by the collision between ball bearings and inner and outer races of a bearing assembly.
According to a first aspect of the present invention, a bearing used for a rotary machine includes an inner race, an outer race, and a plurality of balls provided between the inner and outer races. The plurality of balls are arranged in single row, and each of the balls contacts both inner and outer races at two contact points respectively.
Thus, even when the outer ring inclines due to an external force, although each ball detaches from the inner race at one contact point, it continuously contacts the inner race at the other contact point. Similarly, although each ball detaches from the outer race at one contact point, it continuously contacts the other contact point.
Accordingly, the ball does not fall due to the gravity, thereby preventing generation of the noise caused by the collision between the ball and the races.
According to a second aspect of the present invention, radius of curvatures of the raceway surfaces, which contact the ball, are larger than the radius of the ball at portions where the raceway surfaces contact the ball.
Thus, each ball can contact both inner and outer races at two contact points respectively.
According to a third aspect of the present invention, a space between the inner and outer races, where the ball is disposed, is sealed by a seal member, and grease is charged into the space.
The grease works as a cushion between the balls and the inner and outer races to reduce a noise caused by collision between the balls and the races. Further, the space to which the grease is charged is sealed by the seal member, so that the grease does not leak, thereby continuously reducing the noise.
According to a fourth aspect of the present invention, an action line of the external force axially diverts from a radial central line. Thus, when the outer race inclines, the ball contacts both inner and outer races at least at one point respectively.


REFERENCES:
patent: 3762516 (1973-10-01), Matsushita et al.
patent: 4210890 (1980-07-01), Olsen
patent: 5232076 (1993-08-01), Nakagawa et al.
patent: 6010420 (2000-01-01), Niki et al.
patent: 6116786 (2000-09-01), Takata et al.
patent: 19633699 (1997-02-01), None
patent: 6-66330 (1994-03-01), None
patent: 9-119510 (1997-05-01), None

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