Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2001-01-31
2003-04-29
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S450000
Reexamination Certificate
active
06554480
ABSTRACT:
BACKGROUND OF THE INVENTION
A single row deep groove radial ball bearing according to the present invention is used to support a rotary member such as a pulley and to removably support an offset load.
Automotive accessories such an alternator and a compressor are driven to rotate by an engine for driving a vehicle. Due to this, an endless belt is extended between follower pulleys fixed to end portions of rotating shafts of the automotive accessories and a drive pulley fixed to an end portion of a crankshaft of the driving engine, and the rotating shafts are constructed to be driven to rotate based on the circulation of the endless belt.
FIG. 5
illustrates the construction of a rotational driving portion of a rotating shaft
1
of a compressor constituting an automotive air conditioner. The rotating shaft is rotatably supported by rolling bearings, not shown, within a casing
2
. A follower pulley
4
is rotatably supported around the circumference of a supporting tube portion
3
provided on an outer circumference of an end portion of the casing
2
by a single row deep groove radial ball bearing
5
. The follower pulley
11
is formed into an annular configuration, on the whole, which has substantially a U-shaped cross section, and a solenoid
6
which is fixed to an end face of the casing
2
is disposed within an internal space of the follower pulley
4
. On the other hand, a mounting bracket
7
is fixed to a portion protruding from the casing
2
at an end portion of the rotating shaft
1
, and an annular plate
21
of a magnetic material is supported on the circumference of the mounting bracket
7
via a plate spring
8
. The annular plate
21
is spaced away from the follower pulley
4
, as shown in
FIG. 5
, when the solenoid
6
is not energized, while when the solenoid
6
is energized, the annular plate
21
is drawn toward the follower pulley
4
so as to be secured thereto, so that a rotational force is free to be transmitted from the follower pulley
4
to the rotating shaft
1
.
With the rotational supporting device as described above, there maybe a case where a transverse central position (a chain line &agr; in
FIG. 5
) of the endless belt wound around an outer circumference of the follower pulley
4
is not allowed to coincide with a transverse central position (a chain line &bgr; in
FIG. 5
) of the single row deep groove radial ball bearing
5
. In such a case, a moment load in proportion to a deviating amount (offset amount) &dgr; between the transverse central positions of the two members is applied to the single row deep groove radial ball bearing
5
based on the tension of the endless belt. Then, a central axis of an inner ring
9
and a central axis of an outer ring
10
which constitute the single row deep groove radial ball bearing
5
do not coincide with each other (they are inclined).
With a mechanism like one as described above, when the central axes of the inner ring
9
and the outer ring
10
do not coincide with each other, there occurs an unbalanced wear of the endless belt which is wound around the outer circumference of the follower pulley
4
, this making it difficult to secure the durability of the endless belt. In addition, the inclination of the central axes also makes it impossible to secure a certain gap between the annular plate
21
and the follower pulley
4
, resulting in a possibility that these two members
21
,
4
come into friction with each other. In the event that such a friction occurs, abnormal wear and abnormal noise are likely to be generated unfavorably. With a view to preventing the occurrence of these inconveniences, it is considered to reduce an angular gap of the single row deep groove radial ball bearing
5
in order to make it difficult that the central axes of the inner ring
9
and the outer ring
10
discord with each other.
Then, in order to reduce the angular gap for the aforesaid purpose, the following (1) to (4) procedures will be contrived.
(1) Radius of curvatures of cross-sectional shapes of an inner ring raceway
11
formed in an outer circumferential surface of the inner ring
9
and an outer ring raceway
12
formed in an inner circumferential surface of the outer ring
10
are made small (they are to be reduced so as to approximate 50% of the outside diameter of balls
13
constituting the single row deep groove radial ball bearing
5
).
(2) As shown in
FIG. 6
, the raceway surface of one or both of an inner ring raceway
11
a
in an outer circumferential surface of an inner ring
9
a
and an outer ring raceway
12
a
in an inner circumferential surface of an outer ring
10
a
is formed into a combined surface, and rolling surfaces of balls
11
are brought into contact with both the raceway surfaces at three or four points.
(3) As shown in
FIG. 7
, the heights of shoulder portions
14
a
,
14
b
existing on transverse (in left and right directions in
FIG. 7
) sides of the raceway surface of one or both of an inner ring raceway
11
b
in an outer circumferential surface of an inner ring
9
b
and an outer ring raceway
12
b
in an inner circumferential surface of an outer ring
10
b
are made higher as indicated by a solid line than a general height indicated by a chain line in the same figure.
(4) As shown in
FIG. 8
, a plural row radial ball bearing
15
is used in which a plurality of balls
13
,
13
are provided between a plurality of inner ring raceways
11
c
,
11
c
formed in an outer circumferential surface of an inner ring
9
c
and between a plurality of outer ring raceways
12
c
,
12
c
formed in an inner circumferential surface of an outer ring
10
c
, respectively.
The conventionally known and contrived constructions for reducing the angular gap as described above have the following problems.
First of all, in the case of the construction described under (1), although the angular gap can be reduced, the contact ellipses existing at abutting portions of the rolling surfaces of the respective balls and the inner ring raceway
11
and the outer ring raceway
12
become larger. Then, the contact ellipses dislodge from the inner ring raceway
11
and the outer ring raceway
12
when the central axes of the inner ring
9
and the outer ring
10
are only inclined slightly by virtue of a moment load. In this state, the rolling fatigue life of the rolling surface becomes extremely short. Thus, the construction described under (1) is not desirable as the allowable moment load becomes small. Note that while the configurations of the contact portions can be ellipse no more (resulting in a configuration in which part of the ellipse becomes lost) when the contact portions between the rolling surfaces and the raceway surfaces reach the transverse end edges of the raceway surfaces, for the purpose of description, a state like this will be referred to as “the contact ellipse dislodges from the raceway surface” in this specification.
Next, with the construction described under (2), the rolling surfaces of the balls
13
and the inner ring raceway
11
a
and the outer ring raceway
12
a
come to contact with each other at a plurality of contact positions, and moreover, in a state in which the engine is driven while the moment load is applied, since the contact positions become asymmetrical relative to the rotating axis of the ball
13
, there occur much wear and heat based on slippage at the contact points, which is not desirable.
Next, with the construction described under (3), since the space between the shoulder portions
14
a
,
14
a
on the outer circumferential surface of the inner ring
9
b
and the shoulder portions
14
b
,
14
b
on the inner circumferential surface of the outer ring
10
b
becomes narrow, the diametrical thickness of a retainer
16
for holding the balls
13
becomes thin. Thus, as the thickness of the retainer
16
becomes thin, since it is difficult to secure the durability of the retainer
16
, in consideration of the durability of the retainer
16
, the effect of reducing the angular gap using the procedure described under (3) is limited.
Furthermore, with the cons
Gotoh Fusasuke
Ishiguro Hiroshi
Ohata Toshihisa
Hannon Thomas R.
NSK Ltd.
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