Ball bearing

Details Ball bearing Ball bearing

2000-10-18

2004-04-13

Joyce, William C. (Department: 3682)

Bearings

Rotary bearing

Antifriction bearing

C384S484000, C384S526000, C384S531000

Reexamination Certificate

active

06719459

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
This invention relate to a ball-bearing retainer (also referred to as cage) and ball bearing, particularly to an improvement of ball bearings used in various rotating mechanical devices and the retainers used in those ball bearings, and more particularly to providing inexpensively a structure to prevent lubrication grease enclosed inside the ball-bearing from leaking out, while at the same time makes it possible to suppress the generation of harmful noise called retainer noise.
BACKGROUND OF THE INVENTION
Ball bearings, such as the ball bearing
1
shown in
FIG. 1
, are widely used for supporting various rotating parts, such as the bearings of various rotating mechanical devices. This ball bearing
1
comprises an inner race
3
, that has a inner-race track (also referred to as raceway)
2
formed around its outer peripheral surface, an outer race
5
, that has an outer-race track
4
formed around its inner peripheral surface, which are located such that they are concentric, and a plurality of balls
6
that are located between the inner-race track
2
and outer-race track
4
such that they can rotate freely. In the example shown in the figure, the inner-race track
2
and outer-race track
4
are both formed in a deep groove shape in addition, the plurality of balls
6
are held in pockets
8
that are formed in the retainer
7
such that they can rotate freely.
The retainer
7
of the ball bearing
1
shown in
FIG. 1
is called a wave-shaped pressed retainer, and is formed by combining a pair of elements
9
that are obtained by pressing a some kind of metal sheet material into a wave-shaped circular ring. Both of these elements
9
are formed with concave sections
10
that form pockets
8
at a plurality of locations around in the circumferential direction.
This pair of elements
9
come together at sections that are separated from the concave sections
10
and are joined and fastened together by a plurality of rivets
11
at these sections to form the retainer
7
which is ring shaped and has the pockets
8
around in the circumferential direction.
The middle section on the inside surface of the concave sections
10
has a radius of curvature that is slightly larger than the radius of curvature of the outside surface or rolling surface of the balls
6
, and forms a partial spherical and concave retaining surface
12
. Therefore, when the pair of elements
9
come together, the concave sections
10
come together to form the pockets
8
.
The retainer
7
shown in
FIG. 2
, called a crown-shaped retainer, comprises a ring-shaped main section
13
that is made of synthetic resin, in which pockets
8
are formed at a plurality of locations around in the circumferential direction for holding the balls
6
such that they can rotate freely. In the case of this kind of crown-shaped retainer
7
, a plurality of elastic pieces
14
are arranged around the main section
13
such that there is a space between them, and the pockets
8
each is defined by the opposing side surfaces of a pair of elastic pieces
14
and a spherical-shaped concave section
15
that is formed between the pair of elastic pieces
14
on the surface on one side (top surface in
FIG. 2
) in the axial direction (vertical direction in
FIG. 2
) of the main section
13
.
The radius of curvature of this concave section
15
is slightly larger than the radius of curvature of the outer surface of the balls
6
. The side surfaces of the elastic pieces
14
and the concave section
15
form a concave retaining surface.
When assembling the ball bearing, the balls
6
are inserted in between the pair of elastic pieces
14
by elastically pressing open the space between the tip ends of the pair of plastic pieces
14
. As soon as balls
6
have been pressed into place, the elastic pieces
14
elastically return to their original shape to hold the balls
6
inside the pockets
8
, and these balls
6
are then held between the inner-race track
2
and outer-race track
4
(see
FIG. 1
) such that they rotate freely.
When using a ball bearing
1
equipped with the retainer
7
described above, the inner race
3
rotates freely with respect to the outer race
5
due to the rolling motion of the balls
6
. At this time, the balls
6
revolve around the inner race
3
as they rotate. Moreover, the retainer
7
rotates around the inner race
3
at the same speed that the balls
6
revolve around the inner race
3
.
Grease is filled in the section between the outer peripheral surface of the inner race
3
and the inner peripheral surface of the outer race
5
in order that they rotate smoothly with respect to each other. Also, together with preventing the generation of vibration or noise in the ball bearing
1
, the grease prevents trouble due to seizure etc. It is not shown in
FIG. 1
, however the openings on both ends in the axial direction of space
16
where the balls
6
are located between the outer peripheral surface of the inner race
3
and the inner peripheral surface of the outer race
5
are covered by a pair of seal plates
17
of the contact type as shown in
FIG. 6
, or of the non-contact type, and these seal plates
7
prevent grease from leaking from the space
16
as well as prevent foreign matter such as dirt from getting inside the space
16
.
The outer peripheral edges of the seal plates
17
fit into seal grooves all the way around the inner peripheral surface on both ends of the outer race
5
, and the inner peripheral edges come in contact with or come very close to the outer peripheral surface on both ends of the inner race
3
.
In the case of the ball bearing
1
with a retainer
7
as described above, vibration of the retainer
7
may be caused even when the ball bearing
1
is filled with or supplied with the required amount of lubricant, so noise or vibration, called ‘retainer noise’ may occur in the ball bearing
1
with this retainer
7
. The vibration of this kind of retainer
7
is due to large movement of the retainer
7
with respect to the balls
6
, which is caused by the sliding friction between the balls
6
and the retainer
7
.
Conventionally, generation of this kind of retainer noise was suppressed by making the gap between the inner surface of the pockets
8
and the rolling surface of the balls
6
smaller in order to reduce the amount of movement of the retainer
7
with respect to the balls
6
.
However, by just reducing the amount of movement of the retainer
7
with respect to the balls
6
, the grease
20
(see FIG.
5
and
FIG. 6
) filled in the space
16
where the balls
6
are located presses against the seal plate
17
from inside the space
16
, making it easy for the grease to leak out. Also, it becomes easy for retainer noise due to the shape of the inner peripheral surface of the pockets
8
to occur. The reason for this is explained using FIG.
3
and FIG.
4
.
In the case of the retainer
7
in the prior art structure, nearly the entire inner peripheral surface of the pockets
8
of the retainer
7
is a spherical concave shape having a radius of curvature that is slightly larger than the radius of curvature of the rolling surface (also referred to as rolling contact surface) of the balls
6
. Also, the edge
18
on the opening of the pockets
8
comes very close to the rolling surface of the balls
6
, as shown in
FIGS. 3 and 4
.
Moreover, by making the gap between the inner surface of the pockets
8
and the rolling surface of the balls
6
smaller in order to suppress the retainer noise, it becomes difficult for the grease
20
to enter the clearance
19
between the rolling surface of the balls
6
and the concave surface
12
of the retainer
7
(in the case shown in FIG.
1
), or between the rolling surface of the balls
6
and the side surfaces of the elastic pieces
14
and the concave section
15
(in the case of the retainer
7
shown in FIG.
2
).
In other words, the grease
20
, that adheres to the rolling surface of the balls
6
and that tries to get into this clearance
19
from the surrounding space as the balls
6

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