Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
1999-07-09
2001-06-26
Bucci, David A. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
Reexamination Certificate
active
06250811
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a tone wheel built-in constant velocity joint for transmitting rotational force to a driven wheel such as the rear wheel of the FR vehicle (front engine rear wheel drive vehicle) or the RR vehicle (rear engine rear wheel drive vehicle), the front wheel of the FF vehicle (front engine front wheel drive vehicle), and the whole wheels of the 4WD vehicle (four wheel drive vehicle), while detecting the rotational speed of the driven wheel.
BACKGROUND OF THE INVENTION
The constant velocity joint is used to transmit the rotational force taken out of the engine through the transmission.
JP Patent Publication KOKAI NO. H7-317754 discloses a conventional rolling bearing unit for vehicle wheel having a constant velocity joint, where the constant velocity joint is combined with the rolling bearing unit, so that the driven wheel is rotatably supported by the suspension while the rotational force is transmitted to the driven wheel.
FIG. 8
shows the conventional structure disclosed in this publication. An outer ring or race
1
is supported by the suspension so as not to rotate when incorporated in the vehicle, and formed with a first mount flange
2
on its outer peripheral surface to be supported by the suspension and with outer ring raceways
3
in double rows on its inner peripheral surface. A hub
4
is provided on the radially inside of the outer ring
1
, and formed with a second mount flange
5
on its outer peripheral surface at the axially outer end (left end in the drawings) to support a vehicle wheel (not shown), with inner ring raceways
6
in double rows on its outer peripheral surface at the axially middle portion, and with a housing
8
for the constant velocity joint
7
at the axially inner end (right end in the drawings). A plurality of rolling members
9
are provided between the outer ring raceways
3
and the inner ring raceways
6
to rotatably support the hub
4
inside the outer ring
1
.
The terms “axially outer” and “axially outside” mean the widthwise outside when installed in the vehicle while the terms “axially inner” and “axially inside” mean the widthwise inside when installed in the vehicle in the present specification.
Substantially cylindrical covers
10
made of a metal plate such as stainless steel and annular seal rings
11
made of elastic member such as elastomer e,g. rubber are provided between the opposite opening portions of the outer ring
1
and the outer peripheral surface at the middle portion of the hub
4
. The covers
10
and seal rings
11
isolate the portion where the rolling members
9
are located, from outside, and prevent the grease in this portion from leaking out to the outside, and the foreign matter such as rain water, dust from entering this portion.
The constant velocity joint
7
comprises, in addition to the housing
8
, an inner ring or inner joint member
12
and balls
13
, which are a rotation or torque transmitting member, respectively. The balls
13
are rotatably supported by a cage
14
. Engaged in a spline joint with the inside of the inner ring
12
is the end of the drive shaft (not shown) which is rotated through the transmission by the engine.
Formed on the outer peripheral surface of the inner ring
12
are a plurality of (e.g. six) inner engagement grooves
15
in arcuate cross section which are circumferentially arranged with a uniform interval to extend at right angles with reference to the circumferential direction.
Formed on the inner peripheral surface of the housing
8
facing the inner engagement grooves
15
are a plurality of outer engagement grooves
16
in arcuate cross section which are circumferentially arranged to extend at right angles with reference to the circumferential direction.
The balls
13
can roll along the inner and outer engagement grooves
15
,
16
when supported by the pockets
17
of the cage
14
, respectively.
When installing into the vehicle the rolling bearing unit integral with the constant velocity joint as constructed above, the outer ring
1
is supported by the suspension through the first mount flange
2
while for example the front wheel, that is a driven wheel, is connected to the hub
4
through the second mount flange
5
. The end portion of the drive shaft (not shown) is engaged in a spline joint with the inside of the inner ring
12
of the constant velocity joint to be rotatably driven by the engine through the transmission.
When the vehicle is moving, the rotation of the inner ring
12
is transmitted to the hub
4
through the balls
13
to rotate the driven wheel, e.g. front wheel.
There is a problem that the conventional rolling bearing unit for vehicle wheel as shown in
FIG. 8
is hard to make the unit compact and lightweight. The reason is as follows;
In the constant velocity joint
7
integrally combined with the rolling bearing unit, six inner engagement grooves
15
, six outer engagement grooves
16
and six balls
13
are used. In this case, in order to transmit the required torque keeping the rolling fatigue life of the inner engagement grooves
15
and outer engagement grooves
16
and of the rolling contact surfaces of the balls
13
of the constant velocity joint, the outer diameter of the balls
13
of the constant velocity joint
7
must be large in a degree. Accordingly, in the conventional rolling bearing unit for the vehicle wheel, the diameter of the circumscribing circle of the outer engagement grooves
16
determined by the size of the diameter of the circumscribing circle of the balls
13
is larger than the diameter of the inner ring raceways
6
on the outer peripheral surface at the middle portion of the hub
4
.
Therefore, in the conventional rolling bearing unit for the vehicle wheel, the rolling bearing section comprising the outer ring
1
, hub
4
and rolling members
9
and the section of the constant velocity joint
7
are arranged in series in the axial direction as shown in FIG.
8
. However, in this series arrangement, the whole axial size of the rolling bearing unit for the vehicle wheel is larger, and by that amount, the whole apparatus weight is larger. The weight increase of the rolling bearing unit increases the unspring weight of the vehicle, which would worsen the ride comfortability and fuel consumption performance. Therefore, making the rolling bearing unit for the vehicle wheel compact and lightweight is required.
Under such a situation, the present inventors invented the rolling bearing unit for the vehicle wheel combined with the constant velocity joint disclosed in JP Patent Application No. H9-191433.
In the rolling bearing unit for the vehicle wheel combined with the constant velocity joint of this patent application, as shown in
FIG. 9
, the number of the inner engagement grooves
15
on the outer peripheral surface of the inner ring or inner joint member
12
, the outer engagement grooves
16
on the inner peripheral surface of the housing
8
a
of the constant velocity joint
7
a,
which is provided on the axially inner end of the hub
4
a,
and the balls
13
between the inner and outer engagement grooves
15
and
16
are seven or more (e.g. 8-12), respectively, so that the load applied to the balls
13
during use of the rolling bearing unit is smaller than in the conventional structure. By that amount, the outer diameter of the balls
13
is made smaller, so that the diameter of the circumscribing circle of the balls
13
arranged in an annular shape, and the diameter of the circumscribing circle of the outer engagement grooves
16
are made smaller than the diameter of at least the axially inside one of the inner ring raceways
6
which are formed on the outer peripheral surface of the middle portion of the hub
4
a
. In addition, the axially inside one of the inner ring raceways
6
is made to overlap part (the left part in
FIG. 9
) of the outer engagement grooves
16
in the radial direction.
The operation to rotatably support the vehicle wheel to the suspension by the rolling bearing unit of this application is substantially the same to that of t
Mitsue Naoki
Mizukoshi Yasumasa
Onose Yoshiaki
Ouchi Hideo
Bucci David A.
Crowell & Moring , L.L.P.
Hansen Colby
NSK Ltd.
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