Rolling bearing unit and constant velocity joint for wheels

Details Rolling bearing unit and constant velocity joint for wheels Rolling bearing unit and constant velocity joint for wheels

1998-07-16

2002-04-09

Browne, Lynne H. (Department: 3629)

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

Coupling accommodates drive between members having...

Coupling transmits torque via radially spaced ball

C384S497000

Reexamination Certificate

active

06368223

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a rolling bearing unit and constant velocity joint for wheels, specifically a rolling bearing unit and constant velocity joint for rotatably supporting a front wheel of the automobile of the front engine front wheel drive (FF) type or four wheel drive (4WD) with respect to the suspension.
BACKGROUND OF THE INVENTION
In order to rotatably support a vehicle wheel or road wheel with respect to the suspension, various kinds of rolling-bearing units for wheels have been used wherein outer and inner races or rings can rotate freely by way of rolling members. Here, when a rolling-bearing unit for supporting the front wheel of the FF automobile or 4WD automobile, which is the driven wheel as well as the steering wheel, is combined with a constant velocity joint, it is necessary that rotation of the drive shaft be transmitted smoothly (maintaining uniform speed) to the vehicle wheel regardless of the steering angle applied to the vehicle wheel.
Also, when a rolling-bearing unit for supporting the driven wheel of the automobile with the independent type suspension is combined with a constant velocity joint, it is necessary that rotation of the drive shaft be transmitted smoothly (maintaining uniform speed) to the vehicle wheel regardless of the relative displacement between the differential gear and the driven wheel and of the steering angle applied to the vehicle wheel.
WO 97/24538 disclosed an eight ball constant velocity joint wherein (1) the ratio of the pitch circle diameter of the torque transmitting balls to the diameter of the torque transmitting balls is between 3.3 to 5.0, and (2) the ratio of the outer diameter of the outer joint member to the pitch circle diameter of the tooth profile of the inner joint member is set within the range from 2.5 to 3.5.
However, U.S. Pat. No. 5,221,233 had disclosed prior to WO 97/24538 an eight ball constant velocity joint, wherein determining the dimension relation of (1) and (2) above is an inherent setting matter under the limited conditions, which can be practically set by a person skilled in the art in the most optimum values taking into consideration the strength of the outer joint member, the strength of the inner joint member, and the strength of the cage.
In addition, in the eight ball constant velocity joint of WO 97/24538, (3) the cage has short and long pockets, the short pockets being arranged with a space of 180 degrees between them.
However, U.S. Pat. No. 5,509,856 (filed on Oct. 13, 1993, its German counterpart is published on Mar. 24, 1994) disclosed a technology of the six ball constant velocity joint where the width of the posts (webs or column sections) of the cage is sufficiently kept while being capable of incorporating the balls in it.
Specifically, since the balls already incorporated move circumferentially in the cage pockets when the cage is tilted to incorporate the remained balls, the pockets must be longer by that amount.
However, the last two balls for incorporation to be spaced apart from each other with a space of 180 degrees is not required to move circumferentially, so that the pockets spaced apart 180 degrees for the last two balls can be shorter. Therefore, the width of the posts (webs or column sections) of the cage can be wider to improve the cage strength.
On the other hand, U.S. Pat. No. 5,221,233 discloses a technology to make the number of balls eight to increase the load capacity. Upon combining these technologies, the former technology to make the incorporation convenient has no relation with the latter technology to increase the load capacity. Accordingly, there is no relation between the arrangement of shorter pockets spaced apart 180 degrees and the increase of balls from six to eight, and there is no special technical meaning in combining such technologies.
A relatively compact and lightweight rolling-bearing unit for wheels used with this kind of constant velocity joint has been disclosed in Japanese Patent Publication TokuKai-Hei No.7-317754.
FIG. 1
shows the construction of the bearing described in this disclosure. When installed in the vehicle or automobile, the outer race or ring
11
, which does not rotate when supported by the suspension, has a first installation flange
12
for supporting it to the suspension around its outer peripheral surface and a double row of outer-nag raceways
13
around its inner peripheral surface. Disposed on the inside of the outer race or ring
11
is a hub
16
which comprises a first inner race or ring
14
and a second inner ring
15
.
The first inner ring
14
has a second installation flange
17
for supporting the vehicle wheel on one end portion (left end portion in
FIG. 1
) and a first inner ring raceway
18
on the other end portion (right end portion in FIG.
1
), both of which are cylindrical shaped.
The second inner ring
15
has a cylindrical section
19
on one end portion (left end in
FIG. 1
) for fitting the first inner ring
14
thereon, a housing portion
52
, which is the outer member or ring of the constant velocity joint
1
(detailed later), on the other end portion (right end in FIG.
1
), and a second inner ring raceway
20
around the outer peripheral surface in the middle portion. By placing several rolling members
21
between the outer-ring raceways
13
and the first and second inner-ring raceways
18
,
20
, respectively, the hub
5
can rotate freely inside the outer ring
11
.
Moreover, a first attachment groove
22
is formed in the inner peripheral surface of the first inner ring
14
and a second attachment grooves
23
is formed in the outer peripheral surface of the second inner ring
15
, where the first and second attachment grooves
22
,
23
come together in alignment, and by placing a retaining ring
24
in both of these attachment grooves
22
,
23
, the first inner ring
14
is prevented from coming out of the second inner ring
15
.
Furthermore, the outer peripheral edge of one end face (left end face in
FIG. 1
) of the second inner ring
15
is joined to the inner peripheral edge of a stepped section
25
formed around the inner peripheral surface of the first inner ring
14
by a weld
26
, such that the first ring
14
and second inner ring
15
are joined together.
Also, a substantially cylindrical shaped cover
27
a
and a circular ring shaped seal ring
28
a
are located between the opening portion at one end of the outer ring
11
and the corresponding outer peripheral surface portion in the middle portion of the hub
16
while a substantially cylindrical shaped cover
27
b
and a circular ring shaped seal ring
28
b
are located between the opening portion on the other end of the outer a ring
11
and the corresponding outer peripheral surface portion in the middle portion of the hub
16
. The substantially cylindrical shaped covers
27
a
,
27
b
are made of metal such as stainless steel, and the circular ring shaped seal rings
28
a
,
28
b
are made of elastic material such as rubber or elastomer.
These covers
27
a
,
27
b
and seals
28
a
,
28
b
seal of the area where the rolling members
21
are located from the outside, which prevents the grease in this area from leaking out, and also rain water, dirt or other foreign matter from getting into this area.
Moreover, there is a partition plate
29
inside of the middle portion of the second inner ring
15
to close off the inside of the second inner ring
15
, which maintains the rigidity of the second inner ring
15
, and prevents foreign matter that has gotten into the inside of the second inner ring
15
through the opening on the one end (left end in
FIG. 1
) from reaching the constant velocity joint
1
located on the inside of the housing portion
52
.
The constant velocity joint
1
comprises an inner member or ring
2
, retainer or cage
9
and multiple balls (engagement balls)
4
in addition to the housing portion
52
. Of these components, the inner ring
2
is attached to the end of the drive shaft (not shown in the figures) which is driven and rotated by the engine by way of the

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