Rotary shafts – gudgeons – housings – and flexible couplings for ro – Housing – With rolling body supporting shaft in housing
Reexamination Certificate
2001-10-10
2004-03-30
Binda, Greg (Department: 3679)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Housing
With rolling body supporting shaft in housing
C464S906000, C384S589000
Reexamination Certificate
active
06712707
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bearing device for a driving wheel for rotatably supporting a driving wheel of an automobile on an automobile body.
2. Description of the Related Art
Different types of bearing devices for driving wheels of automobiles have been proposed depending on use. For example, a bearing device shown in
FIG. 4
has as major structural elements a hub ring
101
, an inner ring
102
, rolling elements
103
and
104
of double rows, an outer ring
105
, and a constant velocity universal joint
106
.
The hub ring
101
is formed with an outboard raceway
107
on its outer peripheral surface and provided with a wheel-mounting flange
109
for mounting a wheel. Hub bolts
110
for fixing a wheel disk are provided on a wheel-mounting flange
109
at equal intervals in a circumferential direction. The inner ring
102
is fitted onto a small-diameter stepped portion
111
formed on an outer peripheral surface of an inboard-side end portion of the hub ring
101
, and an inboard raceway
108
is formed on an outer peripheral surface of the inner ring
102
.
The inner ring
102
is pressed into position with an appropriate interference in order to prevent its creeping. Raceways of double rows are constituted by the outboard raceway
107
formed on the outer peripheral surface of the hub ring
101
and by the inboard raceway
108
formed on the outer peripheral surface of the inner ring
102
. The inner ring
102
is pressed onto the small-diameter stepped portion
111
of the hub ring
101
, and a joint outer ring
121
is inserted into the hub ring
101
from its inboard side in an axial direction. Then, the joint outer ring
121
is fastened with the hub ring
101
. With this process, an end portion of the inner ring
102
is butted against a shoulder portion
128
of the joint outer ring
121
, so that the inner ring
102
is prevented from loosening and preload to a bearing portion
115
is controlled.
On an inner peripheral surface of the outer ring
105
, raceways
112
and
113
of double rows are formed, which oppose to the raceways
107
and
108
of the hub ring
101
and the inner ring
102
, and the outer ring
105
is provided with an automobile-body-mounting flange
114
for mounting a bearing device on automobile body. The flange
114
is fixed with bolts to a knuckle extending from a suspension device of the automobile body.
The bearing portion
115
is of a double-row angular ball bearing structure in which the rolling elements
103
and
104
are provided between a group of the raceways
107
and
108
formed on outer peripheral surfaces of the hub ring
101
and the inner ring
102
and a group of raceways
112
and
113
formed on an inner peripheral surface of the outer ring
105
, and the rolling elements
103
and
104
in each row are supported by cages
116
and
117
at equal intervals in a circumferential direction.
At opening portions of both ends of the bearing portion
115
, a pair of seals
118
and
119
sealing an annular space formed by the outer ring
115
, the hub ring
101
and the inner ring
102
is fitted into an inside of the hole at an end portion of the outer ring
105
so as to prevent leakage of grease filled inside and ingress of water or foreign matters from outside.
The constant velocity universal joint
106
comprises the joint outer ring
121
provided at one end of the shaft
139
and formed with the track groove
120
on its inner peripheral surface, a joint inner ring
141
on an outer peripheral surface of which a track groove
140
opposing to the track groove
120
of the joint outer ring
121
is formed, balls
142
installed between the track groove
120
of the joint outer ring
121
and the track groove
140
of the joint inner ring
141
, and a cage
143
provided between the joint outer ring
121
and the joint inner ring
141
for supporting the balls
142
.
The joint outer ring
121
has a mouth portion
122
accommodating the joint inner ring
141
, the balls
142
and the cage
143
, and a shaft portion
123
, extending in an axial direction from the mouth portion
122
and being formed with a serrated portion
124
on its outer peripheral surface. The shaft portion
123
is inserted into a through-hole of the hub ring
101
so that they are fitted together through serrated portions
124
and
125
formed on the outer peripheral surface of the shaft portion
123
and an inner peripheral surface of the through-hole, respectively. Then, the constant velocity universal joint
106
is fixed to the hub ring
101
by tightening a nut
127
on an external thread portion
126
formed on an end of the shaft portion
123
. Preload of the bearing portion
115
is controlled by axial forced applied by tightening the nut
127
.
In the bearing device in
FIG. 4
, preload of the bearing portion
115
is controlled by tightening torque of the nut
127
, while in the bearing device shown in
FIG. 5
in which a swaging process is employed in assembling it, preload control by fastening torque of the nut
127
is not required.
In this bearing device, a projection end portion of the small-diameter stepped portion
111
of the hub ring
101
is swaged by plastically deforming it toward an outside-diameter side, and the hub ring
101
and the inner ring
102
are unitized together by the swaged portion, or a swaged portion
131
, by which the inner ring
102
is prevented from loosening and preload of the bearing portion
115
is controlled. Therefore, when engaging a bolt
133
into a threaded hole
132
formed on the shaft portion
123
of the joint outer ring
121
after inserting the shaft portion
123
through the though-hole of the hub ring
101
, the joint outer ring
121
is fixed to the hub ring
101
with tightening torque that is necessary and sufficient to prevent the joint outer ring
121
from loosening.
On the other hand, in a bearing device using balls as the rolling elements
103
and
104
, because the contact angle is set to about 35°, loads acting on the inner ring
102
in a direction of forming a contact angle are also taken at the swaged portion
131
of the hub ring
101
butted against the shoulder portion
128
of the joint outer ring
121
. Here, the term “contact angle” means the angle measured between the lines of action of force transmitted to the rolling elements
103
and
104
by the raceways
107
and
108
, and a plane (or a radial plane) perpendicular to the axis of a bearing.
Accordingly, the small-diameter stepped portion
111
of the hub ring
101
and the raceway
108
of the inner ring
102
tend to be deformed by loads acting in a direction of forming a contact angle. With increasing amount of deformation of the small-diameter stepped portion
111
of the hub ring
101
, the possibility of breakage of the hub ring
101
and fretting between the hub ring
101
and the inner ring
102
increases. Further, an increased amount of deformation of the raceway
108
of the inner ring
102
tends to cause deterioration of rolling service life, rise in temperature on the raceway
108
, and loss in axial force (or preload) caused by fretting between the inner ring
102
and the shoulder portion
128
of the joint outer ring
121
. When the small-diameter stepped portion
111
of the hub ring
101
and the raceway
108
of the inner ring
102
become to tend to undergo deformation as described above, strain produced inside the bearing may cause deterioration of service life of the bearing device.
SUMMARY OF THE INVENTION
An object of the invention is to improve the service life of a bearing device by preventing strain from being generated inside the bearing device, in which the strain is caused by deformation of a hub ring and an inner ring by loads acting in a direction of forming a contact angle.
A bearing device for a driving wheel of the invention includes an outer member on an inner peripheral surface of which raceways of double rows are formed, an inner member on an outer peripheral surface of which raceways opposing to the raceway
Ogura Hiroyuki
Takubo Takayasu
Torii Akira
Arent Fox Kintner & Plotkin & Kahn, PLLC
Binda Greg
NTN Corporation
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