Rolling bearing unit for vehicle wheel

Details Rolling bearing unit for vehicle wheel Rolling bearing unit for vehicle wheel

1998-12-15

2001-02-20

Browne, Lynne H. (Department: 3629)

Rotary shafts, gudgeons, housings, and flexible couplings for ro

Housing

With rolling body supporting shaft in housing

C464S145000, C464S906000

Reexamination Certificate

active

06190262

ABSTRACT:

THE BACKGROUND OF THE INVENTION
The present invention relates to a rolling-bearing unit for a wheel which is called a fourth-generation hub unit and is used for supporting the driven wheels {front wheels for a FF vehicle (front-engine front-wheel drive vehicle), rear wheels for a FR vehicle (front-engine rear-wheel drive vehicle) and RR vehicle (rear-engine rear-wheel drive vehicle) and all wheels for a 4WD vehicle (four-wheel drive vehicle)} that are supported by an independent-type suspension such that they rotate rotate freely with respect to the suspension device.
In order to support the wheels such that they are able to freely with respect to the suspension device, various kinds of rolling-bearing units for wheels have been used which comprises an outer race and inner race that rotate freely by way of rolling members. Moreover, a rolling-bearing unit for wheels that is used in an independent-type suspension device for supporting the driven wheels, must be combined with a constant velocity joint and smoothly (maintaining constant velocity) transmit the rotation of the drive shaft to the wheels regardless of the relative displacement of the differential gear and drive shaft or of the steering angle applied to the wheels. This kind of rolling-bearing unit for wheels, which is combined with a constant velocity joint, and can be configured such that it is relatively compact and light weight, is called a fourth-generation hub unit, and has previously been known as disclosed in Patent Publication No. Toku Kai Hei 7-317754.
FIG. 1
shows the construction as disclosed in the aforementioned patent publication. With rolling-bearing unit installed in the vehicle, an outer race
1
(outer ring like member) is supported by the suspension device such that it does not rotate, and it has a first installation flange
2
formed around its outer peripheral surface for attaching it to the suspension device, and multiple rows of outer-ring raceways
3
formed around its inner peripheral surface. On the inside of this outer race
1
, there is a hub
6
which comprises a first inner-race member
4
and a second inner-race member
5
. Of these, the first inner-race member
4
is of a cylindrical shape and has a second installation flange
7
for supporting the wheel formed on one end side (left end side in FIG.
1
), and a first inner-ring raceway
8
formed around its other end side (right end side in
FIG. 1
) around its outer peripheral surface, respectively. With respect to this, the second inner-race member
5
has a cylindrical section
9
on one end (left end in
FIG. 1
) for fitting around and attaching to the first inner-race member
4
, and a housing portion
11
, on its other end (right end in FIG.
1
), which acts as the outer ring of a constant velocity joint
10
of the Rzeppa-type and a second inner-ring raceway
12
formed around its outer surface in the center section. Moreover, by placing multiple rolling member
13
between the outer-ring raceways
3
and the first and second inner-race raceways
8
,
12
, it is possible to support the hub
6
on the inside of the outer race
1
such that it can rotate freely.
Also, attachment grooves
14
,
15
are formed around the inner peripheral surface of the first inner-race member
4
and the outer peripheral surface of the second inner-race member
5
in the location where they come together, and a stopping ring
16
is placed in both of these attachment grooves
14
,
15
to prevent the first inner-race member
4
from coming out of the second inner-race member
5
. Furthermore, welding
18
is performed between the outer peripheral edge of one end face (left end face in
FIG. 1
) of the second inner-race member
5
and the inner peripheral edge of a step section
17
that is formed around the inner peripheral surface of the first inner-race member
4
, and it joins and fastens the first and second inner-race member
4
,
5
together.
Also, between the opening on both ends of the outer race
1
and the outer surface in the center of the hub
6
, there are cylindrical shaped covers
19
a
,
19
b
that are made of metal such as stainless steel, and ring shaped seal rings
20
a
,
20
b
that are made of an elastic material such as rubber or elastomer. These covers
19
a
,
19
b
and seal rings
20
a
,
20
b
isolate the area where the multiple rolling members
13
are located from the outside, and they present the grease in that section from leaking out, as well as foreign matter such as rain water or dirt from getting inside this section. Moreover, on the inside of the center section of the second inner-race member
5
, there is a partition plate
21
that closes off the inside of this second inner-race member
5
, and it helps maintain the rigidity of the second inner-race member
5
, as well as prevents foreign matter that gets inside this second inner-race
5
through the opening on the tip end (left end in
FIG. 1
) of this second inner-race member
5
from reaching the section of the constant velocity joint
10
that is located inside the housing
11
.
Moreover, the constant velocity joint
10
comprises the housing
11
, inner ring
22
, retainer
23
and multiple ball
24
. Of these, the inner ring
22
is driven and rotated by the engine by way of the transmission, and is attached to the tip end of the drive shaft (not shown in the drawings). Around the outer peripheral surface of this inner ring
22
there are six inside engagement grooves
25
which have a circular arc shaped cross section when cut along an imaginary plane that crosses the center axis of this inner ring
22
, and they are spaced at equal intervals around in the circumferential direction and are orthogonal to the circumferential direction. Also, around the inner peripheral surface of the housing
11
at locations that face the inside engagement grooves
25
, there are six outside engagement grooves
26
that also have a circular arc shaped cross section and arc orthogonal to the circumferential direction. Moreover, the retainer
23
is ring shaped with a circular arc shaped cross section and it is held in place between the outer peripheral surface of the inner ring
22
and the inner peripheral surface of the housing
11
. At six locations in the circumferential direction around this retainer
23
, at positions that is in alignment with the inside and outside engagement grooves
25
,
26
, there are pockets
27
, and a ball
24
is held in each of the six pockets
27
for a total of six balls
24
. These balls
24
are held in the pockets
27
, and are able to rotate freely along the inside and outside engagement grooves
25
,
26
.
When the rolling-bearing unit for wheels constructed as described above is installed in a vehicle, the outer race
1
is supported by the suspension device by the first installation flange
2
, and the driven wheel is attached to the first inner-race member
4
by the second installation flange
7
. Moreover, the tip end of the drive shaft (not shown in the drawings) is rotated and driven by the engine by way of the transmission, and it is connected to the inside of the inner ring
22
of the constant velocity joint by splines. When the vehicle is operated, the rotation of the inner ring
22
is transmitted to the hub
6
, which includes the second inner-race member
5
, by way of the multiple balls
24
, and rotates and drives the driven wheel.
In the case of the prior rolling-bearing unit for wheels shown in
FIG. 1
, it is difficult to make it compact and lightweight. The reason for this is as follows. When transmitting rotating power between the inner ring
22
and the housing
11
of the constant velocity joint
10
, the inside and outside engagement grooves
25
,
26
and the ball
24
displace relative to the direction of contact between the rolling contact surface of the ball
24
and one side surface in the circumferential of the engagement grooves
25
,
26
, as shown exaggeratedly in
FIGS. 2 and 3
. As a result of this relative displacement, the balls
24
are displaces such that they ride up toward the openin

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