Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2001-12-07
2004-09-28
Footland, Lenard A. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S589000
Reexamination Certificate
active
06796714
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a rolling-bearing unit for wheel support for supporting an automobile wheel such that it rotates freely with respect to the suspension.
2. Description of the Related Art
A rolling-bearing unit for wheel support is used for supporting automobile wheels such that they rotate freely with respect to the suspension.
FIG. 6
shows a first example of a rolling-bearing unit for wheel support that was previously considered for this purpose. This rolling-bearing for wheel support comprises an outer-race
1
, a hub
2
and a plurality of rolling elements
3
a
,
3
b
. Of these, the outer-race
1
has a double row of outer-ring raceways
4
a
,
4
b
formed around its inner peripheral surface and an installation section
5
formed around its outer peripheral surface for fastening to the suspension. Moreover, the hub
2
is located radially on the inside of the outer-race
1
such that it is concentric with the outer-race
1
.
There is a flange
6
formed around the outer peripheral surface on the outside end (This is the outside end in the axial direction which is on the outside in the width direction of the vehicle when the bearing is installed in the automobile, and is the left end in the figures.) of this hub
2
for supporting and fastening to the wheel, and a double row of inner-ring raceways
7
a
,
7
b
are formed around its outer peripheral surface. In addition, there is a plurality of rolling elements
3
between the inner-ring raceways
7
a
,
7
b
and the outer-ring raceways
4
a
,
4
b
, and they are held in place by synthetic resin or metallic retainers
8
such that they rotate freely.
The construction shown in FIG.
6
and
FIG. 7
is provided for supporting a wheel of a relatively heavy vehicle, so tapered rollers are used as the rolling elements
3
a
,
3
b
, and the cross-sectional shape of the outer-ring raceways
4
a
,
4
b
and the inner-ring raceways
7
a
,
7
b
is formed in a straight manner.
Moreover, the hub
2
is formed by combining a hub body
9
and a pair of inner-races
10
a
,
10
b
, and the aforementioned inner-ring raceways
7
a
,
7
b
are formed around the outer peripheral surface of these inner-races
10
a
,
10
b
. In order to combine the hub body
9
with the pair of inner-races
10
a
,
10
b
, a support step section
11
is formed around the outer peripheral surface of the hub body
9
from the middle to the inside end (This is the inside end in the axial direction which is the end toward the middle in the width direction of the vehicle when the bearing is installed in the automobile, and is the right end in the figures.). The pair of inner-races
10
a
,
10
b
is tightly fitted around (pressure fitted) around this support step section
11
through interference fit. Furthermore, a crimped section
13
that is formed by plastically deforming a cylindrical section
12
is formed on the inside end of the hub body
9
, and the inside end surface of the inner-race
10
b
on the axial inside is retained by the crimped section
13
. A step section
14
is located on the outside end of the support step section
11
, and by holding the pair of inner-races
10
a
,
10
b
between the crimped section
13
and the step section
14
, the inner-races
10
a
,
10
b
are fastened to the hub body
9
. Also, with the inside end of the inner-race
10
b
held by the crimped section
13
, a pre-load is applied to the bearing section comprising the rolling elements
3
and raceways
4
,
7
. Construction, in which the technique of holding the inside end of the inner-race with a crimped section is applied to a tapered roller bearing, is disclosed, for example, in International Patent Publication WO 98/58762.
As shown in
FIG. 7
, for the rolling-bearing unit for wheel support that is the object of this invention, the inner-ring raceway
7
a
may also be formed directly around the outer peripheral surface in the middle section of the hub body
9
of the hub
2
. In this case, a support step section
11
on which one inner-race
10
b
is fitted and fixed is formed on only the inside end of the outer peripheral surface of the hub body
9
, and a step section
14
a
for coming in contact with the outside end of this inner-race
10
b
is formed on the hub body
9
itself.
It will be noted that in the case of the pair of inner-races
10
a
,
10
b
shown in
FIG. 6
, the surface of the inside end of the outside inner-race
10
a
corresponds to the aforementioned step section
14
a.
Moreover, in the example shown in the figures, there is a spline hole
15
formed in the center of the hub body
9
of the rolling-bearing unit for supporting the drive wheels. Furthermore, there are seal rings (assembled seal rings)
16
a
,
16
b
between the inner peripheral surface on both ends of the outer-race
1
and the inner-races
10
a
,
10
b
, and they cover the openings on both ends of the space
17
where the rolling elements
3
a
,
3
b
are located.
In the case of the second example shown in
FIG. 7
, the seal ring
16
a
, which covers between the outside end of the outer-race
1
and the middle section of the hub
2
, is fitted around the outside end of the outer-race
1
.
When a rolling-bearing unit for wheel support that is constructed in this way is installed in an automobile, the aforementioned installation section
5
is connected to and fastened to a knuckle or the like of the suspension, and fastens a wheel to the flange
6
. In this way, the wheel is supported such that it rotates freely. Also, a spline shaft that is an accessory of a constant-velocity joint (not shown in the figure) is inserted in the spline hole
15
such that the wheel can be rotated and driven freely by way of the hub body
9
.
A technique for simplifying the work of forming the crimped section
13
for fastening the inner-races
10
a
,
10
b
to the hub body
9
, where the inner-races
10
a
,
10
b
are fitted around the outer peripheral surface of the hub body
9
, is disclosed in West German Patent No. DE3418440A1, and is shown in FIG.
8
and FIG.
9
. In the case of the construction disclosed in this disclosure, in order to form the crimped section
13
for retaining the surface on the inside end of the inner-race
10
b
, concave grooves
18
a
,
18
b
are formed in the circumferential direction around the inner and outer peripheral surfaces on the outside end of the cylindrical section
12
that is formed on the inside end of the hub body
9
. Of these, the concave groove
18
b
that is formed around the outer peripheral surface of the outside end of the cylindrical section
12
, is a small-diameter section as explained later. Since the concave grooves
18
a
,
18
b
are formed to reduce the thickness of the cylindrical section
12
, which becomes the bent section when forming the crimped section
13
, it is easy for the cylindrical section
12
to deform plastically. Therefore, it is possible perform processing of the crimped section
13
without heating the cylindrical section
12
.
The construction shown in FIG.
8
and
FIG. 9
is for supporting the wheel of a relatively lightweight automobile, so balls are used as the rolling elements
3
a
,
3
b
, and the cross-sectional shapes of the outer-ring raceways
4
a
,
4
b
and inner-ring raceways
7
a
,
7
b
are formed in an arc-shape manner.
In the case of the prior art construction shown in FIG.
6
and
FIG. 7
, the relationship between the diameter of the inner-ring raceway
7
a
,
7
b
that is formed around the outer peripheral surface of the inside inner-race
10
b
and the diameter of the crimped section
13
is not particularly regulated, so it was difficult to maintain durability as well as reduce the size and weight. The reason for this is as follows. A large outward axial load is applied to the surface on the inside end of the inner-race
10
b
when forming the crimped section
13
. In addition, when this axial load is applied to the large-diameter-side collar
27
that is formed around the outer peripheral surface on the inside end of the inner-race
10
b
,
Ohkuma Takeo
Shibuya Eishi
Crowell & Moring LLP
Footland Lenard A.
NSK Ltd.
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