Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2001-12-04
2003-11-18
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S533000
Reexamination Certificate
active
06648517
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a retainer for a rolling bearing such as a deep groove ball bearing used in a motor requiring low vibrations and low noises.
A deep groove ball bearing, which is used to support a bearing portion or a rotary portion in various rotary machines, comprises an inner ring having an inner ring raceway of a deep groove formed in the outer peripheral surface thereof, an outer ring disposed concentrically with the inner ring and having an outer ring raceway of a deep groove formed in the inner peripheral surface thereof, and a plurality of balls rollably interposed between the inner and outer rings. The respective balls are rollably held by a retainer, and lubricant such as grease and other kinds of lubricant oil are filled into a space between the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring, in such a manner that the inner and outer rings are allowed to rotate with respect to each other due to the rolling movements of the balls.
Here, as conventional examples of the above-mentioned retainer, there are known retainers which are disclosed in, for example, JP-A-9-144762 shown in
FIG. 9
(which is hereinafter referred to as a prior application art 1), and JP-A-7-208482 shown in
FIGS. 10 and 11
(which is hereinafter referred to as a prior application art 2).
Firstly,
FIG. 9
shows a retainer
2
which is disclosed in the prior application art 1. This retainer is a crown-shaped member formed of, for example, synthetic resin by injection molding and comprises a plurality of pockets
4
formed in the proper positions thereof such as on the circumference thereof; and, on one side of the axial direction of each of the pockets
4
, there is formed an annular-shaped base portion
6
and, on the other side of the pocket axial direction, there is formed an opening
8
set smaller than the diameter of a ball (not shown). The adjoining pockets
4
are separated by a pillar portion
10
, a pair of elastically deformable pawls
12
respectively extend in an arc-shaped manner from the leading end of the pillar portion
10
and cooperate together in defining the opening
8
, and the opening
8
is set smaller than the diameter of a ball (not shown). And, the peripheral edge of the pocket
4
is formed in a concave-shaped spherical surface and, on the leading-end-side area of each pocket
4
, there is provided a projecting portion
12
a
. The projecting portion
12
a
has an arc-shaped section and is disposed along the width-direction curvature of the peripheral surface of the pocket
4
. Due to provision of the projecting portion
12
a
, when a ball is stored in the pocket
4
, the projecting portion
12
a
is elastically contacted with the ball, thereby restricting the self-oscillation of the ball.
Also,
FIGS. 10 and 11
show a retainer
16
which is disclosed in the prior application art 2. In the case of the retainer
16
, between a pair of pawls
19
disposed on one side X of the axial direction of the retainer
16
, there are interposed a plurality of pockets
18
at proper positions such as on the circumference thereof having openings
18
a
, while the dimension of the opening width W of each of the openings
18
a
is set smaller than the diameter D of a ball
20
.
Each pocket
18
includes two side wall surfaces
18
b
respectively disposed on the two sides of the circumferential direction thereof and a bottom wall surface
18
c
disposed opposed to the opening
18
a
of the pocket
187
and, the side wall surface
18
is formed as a concave-shaped spherical surface having a radius of curvature R
1
the center of curvature of which is a point O
1
, while the bottom wall surface
18
c
is formed as a flat surface extending at right angles to the axial direction of the pocket
18
. The radius of curvature R
1
of the side wall surface
18
b
is larger than the radius D/2 of the ball
20
. And, the center O
2
of the ball
20
in the intermediate portion thereof (where the ball
20
is situated in the center of the pocket
18
and is contacted with neither the side wall surfaces
18
b
nor the bottom wall surface
18
c
) is shifted by a dimension S toward one side X of the axial direction of the pocket
18
from the center of curvature O
1
of the side wall surfaces
18
b
, and the ball
20
is shifted toward the opening
18
a
side. The retainer
16
can be moved from this shifted state by a dimension A toward the other side Y of the axial direction thereof and by a dimension B in the circumferential direction thereof until it is contacted with the ball
20
and, at the same time, can be moved by a dimension C toward one side X of the axial direction until the bottom wall surface
18
c
is contacted with the ball
20
.
However, in the prior application art 1, in the process in which the retainer
2
is formed by injection molding, in a step of removing a metal mold, the projecting portion
12
a
interferes with the metal mold, which makes it difficult to manufacture the metal mold. Also, when storing the ball into the retainer
2
, while pressure contacting the ball against the leading ends of the pair of pawls
12
disposed in the openings
8
to thereby spread out them elastically, the ball is stored from the opening
8
into the pocket
4
. Such provision of the projecting portions
12
a
on the pair of pawls
12
reduces the dimension of the opening
8
, thereby raising a fear that the pawls
12
can be damaged or broken when pressure contacting the ball
20
with the leading ends of the pair of pawls
12
.
Also, in the prior application art 2, when the retainer
16
is moved toward one direction X of the axial direction in
FIG. 11
, there is eliminated a clearance for holding the lubricant held between the bottom wall surface
18
c
and ball
20
to thereby worse the lubricating state of the retainer
16
, which increases sliding friction between the bottom wall surface
18
c
and ball
20
. This raises a fear that the pawls
19
can be self-oscillated, which makes it impossible to reduce the noises of the retainer to a satisfactory degree, so that its improvement has been desired.
SUMMARY OF THE INVENTION
The present invention aims at eliminating the above-mentioned drawbacks found in the conventional retainers for a rolling bearing. Accordingly, it is an object of the invention to provide a retainer for a rolling bearing which is structured such that, in the leading end portions of the pawls defining the pocket, there are not provided the projecting portions having disadvantageously influences on the manufacture of a metal mold for injection molding the retainer and on the storing operation of the ball or rolling element into the retainer, and also which can restrict the axial-direction movement of the retainer with respect to the rolling element to thereby be able not only to prevent generation of noises in the retainer but also to enhance the lubricating property of the retainer.
In attaining the above object, according to the invention, there is provided a retainer for a rolling bearing, formed in a circular-ring shape as a whole, comprising: a plurality of pockets formed at a plurality of portions thereof in the circumferential direction thereof for storing and holding rolling elements with the pocket surfaces of the pockets; and, a plurality of openings respectively formed on one side of the axial direction of the respective pockets, each of the openings having an opening width set smaller than the diameter of the rolling element, wherein the ratio of an axial clearance &dgr;, which is formed between the rolling surface of the rolling element in the above axial direction and the pocket surface, to the diameter Da of the rolling element is set in the range of &dgr;/Da=−0.01~0.02 (i.e., &dgr;/Da is in the range between −0.01 and 0.02).
In case where the value of &dgr;/Da exceeds 0.02, when the retainer is going to move in the axial direction with respect to the rolling element, there is a fear that the axial clearance &dgr; increases excessively to cause
Hamamoto Magozou
Ishiwada Hiroshi
Momono Tatsunobu
Mutoh Yasushi
Noda Banda
Hannon Thomas R.
NSK Ltd.
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