Rotary shafts – gudgeons – housings – and flexible couplings for ro – Housing – With rolling body supporting shaft in housing
Reexamination Certificate
2001-02-13
2002-12-03
Swann, J. J. (Department: 3679)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Housing
With rolling body supporting shaft in housing
Reexamination Certificate
active
06488589
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus for driving a wheel of an automobile, and more particularly to a bearing unit for a wheel called a 3.5-generation hub unit in which a constant-velocity joint and hub unit are integrated into one unit. This apparatus is used for supporting a driven wheel that is supported by an independent-type suspension {front wheels for a FF car (front engine, front-wheel drive), rear wheels for a FR car (front engine, rear-wheel drive), rear wheels for a RR car (rear engine, rear-wheel drive) and all the wheels for a 4 WD car (4 wheel drive)} such that the driven wheel rotates freely with respect to suspension, as well as for rotating and driving the driven wheel.
2. Description of the Related Art
In order to support a wheel such that it can rotate freely with respect to the suspension, a wheel-support bearing unit, having an outer race and inner race that rotate freely by way of rolling members, is used. Moreover, in the independent-type suspension, the wheel-support bearing unit, which supports the driven wheel, is combined with a constant-velocity joint, and it must smoothly transmit the rotation of the drive shaft to the driven wheel (maintaining constant velocity) regardless of relative displacement between the differential gear and the driven wheel or the steering angle applied to the driven wheel.
FIG. 3
shows a typical apparatus for the driven wheel of an automobile in which the wheel-support bearing unit
1
is combined with the constant-velocity joint
2
.
Here, the wheel-support bearing unit
1
comprises an outer race
3
on the radially inside of which a hub
4
and inner race
5
rotate freely by way of a plurality of rolling members
6
. Of these, the outer race
3
is fastened to the knuckle
8
(see
FIG. 4
) of the suspension by a first flange
7
that is formed around the outer surface of the outer race
3
such that it does not rotate during operation. In addition, there are rows of outer-ring raceways
9
formed around the inner peripheral surface of the outer race
3
, and the hub
4
and inner race
5
are supported on the radially inside of this outer race
3
such that they are concentric with the outer race
3
.
On the outside end (the outside end in the width direction of the automobile when the bearing unit is installed in the automobile, the left end in
FIGS. 1
to
4
) around the outer peripheral surface of the hub
4
, there is a second flange
10
for supporting the wheel. Moreover, there is a first inner-ring raceway
11
formed around the outer peripheral surface in the middle of the hub
4
, and likewise, the inner race
5
fits around a small-diameter section
12
that is formed on the inside end (the inside end in the width direction of the automobile when the bearing unit is installed in the automobile, the right end in
FIGS. 1
to
4
), and a second inner-ring raceway
13
is formed around the outer peripheral surface of the inner race
5
. There is also a first spline hole
14
formed in the center of the hub
4
.
On the other hand, the constant-velocity joint
2
comprises an outer ring
15
for the constant-velocity joint, an inner ring
16
for the constant-velocity joint, and a spline shaft
17
. Of these, the outer ring
15
for the constant-velocity joint and the spline shaft
17
form a drive shaft member
18
. In other words, this spline shaft
17
is formed on the outside end of this drive-shaft member
18
, and it freely fits in the first spline hole
14
described above, and the outer ring
15
for the constant-velocity joint is formed on the inside end of the drive-shaft member
18
. At a plurality of locations in the circumferential direction around the inner peripheral surface of this outer ring
15
for the constant-velocity joint, there are outside engaging grooves
19
which are formed such that they are each orthogonal with respect to the circumferential direction. Moreover, in the center of the inner ring
16
for the constant-velocity joint there is a second spline hole
20
, and there are inside engaging grooves
21
that are formed such that they are each orthogonal with respect to the circumferential direction and are located around the outer peripheral surface of the inner ring
16
such that they correspond with the location of the aforementioned outside engaging grooves
19
. There are balls
22
located between these inside engaging grooves
21
and outside engaging grooves
19
, and they are supported by a retainer
23
such that they can roll freely along the engaging grooves
21
,
19
. The shape of each of the components of the aforementioned constant-velocity joint
2
are substantially the same as the well-known Rzeppa type constant-velocity joint, and is not essentially related to this invention, so a detailed description will be omitted here.
In the case of a constant-velocity joint
2
and the wheel-support roller-bearing unit
1
as described above, the spline shaft
17
is inserted into the first spline hole
14
in the hub
4
toward the outside from the inside (from right to left in the figure). Also, by screwing a nut
25
onto the male screw section
24
formed on the outside end of the spline shaft
17
on the part that protrudes from the outside end of the hub
4
, and then tightening the nut
25
, the hub
4
and the spline shaft
17
are fastened together. In this condition, the surface on the inside end of the inner race
5
comes in contact with the surface on the outside end of the outer ring
15
for the constant-velocity joint, so the inner race
5
does not move in a direction that would cause it to come apart from the small-diameter step section
12
. At the same time, the rolling members
6
are properly pre-loaded.
Furthermore, when installed in the suspension of an automobile, the male spline
27
that is formed on the outside end of the drive shaft
26
makes a spline fit with the second spline hole
20
that is formed in the center of the inner ring
16
for the constant-velocity joint. A stop ring
29
that fits in the installation groove
28
that is formed all the way around the outer peripheral surface on the outside end of the male spline
27
fits in an anchoring step section
30
that is formed around the edge on the opening on the outside end of the second spline hole
20
, and this prevents the male spline
27
from coming out from the second spline hole
20
. The output shaft section of the differential gear, not shown in the figure, is provided with the trunnion of a tripod-type constant-velocity joint, also not shown in the figure, and the inside end of the drive shaft
26
is connected to the center of the trunnion. As the automobile moves, the drive shaft
26
rotates at constant rpm, however, a thrust load is repeatedly applied in both axial directions due to the resistance of the tripod-type constant-velocity joint that occurs during rotation.
In the wheel drive apparatus for an automobile described above and shown in
FIG. 3
, the wheel-support roller-bearing unit
1
and constant-velocity joint
2
are fastened together by screwing and tightening a nut
25
to the screw section
24
, so the weight of the unit is large. In other words, it is necessary to lengthen the splint shaft
17
by the amount of the male screw section that is formed on the spline shaft
17
on the outside of the constant-velocity joint
2
, as well as a nut
25
is necessary. Therefore, the dimension in the axial direction, as well as the weight, of the wheel drive apparatus for an automobile increases by the amount of the screw section
24
and nut
25
.
In regards to this, as shown in
FIG. 4
, U.S. Pat. No. 4,881,842 discloses a more simple construction that makes it possible to fasten the wheel-support bearing unit and constant-velocity joint in a way such that the dimension in the axial direction is shortened and the weight is reduced. In this second example of prior construction shown in
FIG. 4
, the hub
4
is supported on the radially inside of the outer race
3
, which is fastened to the k
Kayama Shigeoki
Ouchi Hideo
Binda Greg
Crowell & Moring LLP
NSK Ltd.
Swann J. J.
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