Land vehicles: wheels and axles – Wheel – Hub
Reexamination Certificate
2000-02-16
2003-02-25
Stormer, Russell D. (Department: 3617)
Land vehicles: wheels and axles
Wheel
Hub
C188S01800A, C188S2180XL, C029S898090, C384S544000
Reexamination Certificate
active
06523909
ABSTRACT:
This application claims the benefits of Japanese Application Nos. 11-038329 and 11-372393 which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement of a bearing unit for supporting a wheel of an automobile as well as a rotary body for braking such as a rotor or a drum, and to an improvement of a method of manufacturing such bearing unit for the wheel.
2. Related Background Art
A wheel
1
constituting a traveling wheel of an automobile and a rotor
2
constituting a disk brake classified as a braking device, are rotatably supported by a knuckle
3
as a component of a suspension on the basis of, for example, a structure shown in FIG.
4
. To be more specific, a circular support hole
4
is formed in the knuckle
3
. An outer ring
6
defined as a static ring constituting a bearing unit
5
for a wheel, to which the present invention is applied, is fixed to within the support hole
4
a
by use of a plurality of bolts
7
. On the other hand, the wheel
1
and the rotor
2
are fixedly joined through a plurality of studs
9
and a plurality of nuts
10
to a hub
8
as a component of the wheel bearing unit
5
.
Outer ring double raceways
11
a
,
11
b
each serving as a static-side raceway surface are formed in an inner peripheral surface of the outer ring
6
, and a joint flange
12
is provided on an outer peripheral surface thereof. The thus configured outer ring
6
is fixed to the knuckle
3
by joining the joint flange
12
to the knuckle
3
with the bolts
7
.
By contrast, a fitting flange
13
is provided at a portion protruding from an aperture of an outer side end (the term “outer or external” implies an outside portion in a widthwise direction in a state of being assembled to the automobile, i.e., the left side in each drawing. In contrast, the term “inner or internal” implies a central portion in the widthwise direction in the state of being assembled to the automobile, viz., the right side in each of the components.) of the outer ring
6
. The wheel
1
and the rotor
2
are fixedly joined through the studs
9
and the nuts
10
to one single surface (an external surface in the illustrated example) of the fitting flange. Further, an inner ring raceway
14
a
is formed in a portion, facing to the more external raceway
11
a
of the outer ring double raceways
11
a
,
11
b
, of the outer peripheral surface of the intermediate portion of the hub
8
. Moreover, the inner ring
16
is fixedly fitted onto a small-diameter stepped portion
15
provided at an inner side end of the hub
8
. Then, the inner ring raceway
14
b
formed in the outer peripheral surface of the inner ring
16
is disposed facing to the more internal raceway
11
b
of the outer ring double raceways
11
a
,
11
b.
Balls
17
,
17
each defined as a rolling member are provided in a rollable manner by pluralities between the outer ring raceways
11
a
,
11
b
and the inner ring raceways
14
a
,
14
b
in a state of being held by retainers
18
,
18
. Based on this construction, a double-row angular ball bearing with a back face combination is structured, the hub
8
is rotatably supported in the outer ring
6
, and a radial load and a thrust load are supported in a sustainable manner. Note that seal rings
19
a
,
19
b
are provided between inner peripheral surfaces of two side ends of the outer ring
6
, an outer peripheral surface of an intermediate portion of the hub
8
and an outer peripheral surface of an inner side end of the inner ring
16
, thus cutting off a space accommodating the balls
17
,
17
from the outside space. Further, in the illustrated example, the wheel bearing unit
5
is structured for a drive wheel (corresponding to a rear wheel of a FR car and an RR car, a front wheel of an FF car, and whole wheels of a 4WD car), and hence a central portion of the hub
8
is formed with a spline hole
20
. Then, a spline shaft
22
of a constant velocity joint
21
is inserted into the spline hole
20
.
When using the roll bearing unit
5
for the wheel described above, as shown in
FIG. 4
, the outer ring
6
is fixed to the knuckle
3
, and the rotor
2
and the wheel
1
assembled with an unillustrated tire are fixed to the fitting flange
13
of the hub
8
. Further, the rotor
2
of those components is combined with an unillustrated support and an unillustrated caliper which are fixed to the knuckle
3
, thus constituting a disk brake for braking. When braking, a pair of pads provided with the rotor being interposed therebetween are pressed against the two side surfaces of the rotor
2
.
It is a known fact that vibrations called judder followed by disagreeable or annoying noises often occur when braking the wheels of the automobile. One of a variety of known causes of those vibrations may be an ununiform state of frictions between the side surface of the rotor
2
and the lining of the pad, however, deflections of the rotor
2
are also known as another large cause. More specifically, the side surface of the rotor
2
should be fundamentally right-angled to a rotational center of the rotor
2
, however, a perfect perpendicularity is hard to obtain due to an inevitable manufacturing error. As a result, the side surface of the rotor
2
inevitably deflects more or less in directions of the rotational axis (right and left directions in
FIG. 4
) when the automobile travels. If such deflections (displacement quantities in the right and left directions in
FIG. 4
) increase, and if the linings of the pair of pads are pressed against the two side surfaces of the rotor
2
for braking, the judder occurs. Then, the contact between both surfaces of the rotor
2
and the respective linings of the pad becomes non-uniformed, wherein a partial abrasion of the linings is caused.
It is of much importance for restraining the judder occurred by such causes to decrease (axial) deflections of the side surface of the rotor
2
(to enhance the perpendicularity of the side surface to the central axis of rotation). Then, it is required that a perpendicularity of a fitting surface (one side surface of the fitting flange
13
) of the fitting flange
13
to the rotational center of the hub
8
and a surface accuracy of the fitting surface itself be enhanced for restraining those deflections. Factors for exerting influences upon Us the perpendicularity and the surface accuracy might exist by pluralities, however, the factors having an especially large influence may be a parallelism between the fitting surface and the raceway surface (between the outer ring raceways
11
a
,
11
b
and the inner ring raceways
14
a
,
14
b
) with respect to the perpendicularity, and a thermal process deformation with respect to the surface accuracy. Further, for enhancing the parallelism of those factors, among the constructive elements of the hub
8
, there must be a necessity for setting highly accurately a positional relationship between the one side surface of the fitting flange
13
, the inner ring raceway
14
a
formed in the outer peripheral surface of the intermediate portion and the small-diameter stepped portion
15
provided at the inner side end, and configurations and dimensions of those components. If the accuracy of the configurations and the dimensions of the inner ring raceway
14
a
and of the small-diameter stepped portion
15
among those elements are enhanced in the above relationship with the fitting surface, the perpendicularity of the fitting surface to the rotational center of the hub
8
can be enhanced. Moreover, if removing the thermal process deformation out of the fitting surface, the surface accuracy of this fitting surface can also be enhanced.
A technology for preventing the deflection of the fitting flange
13
which might conduce to the deflection of the rotor
2
may be what is disclosed in, e.g., Japanese Patent Application Laid-Open Publication No. 10-217001. The prior art disclosed in this Publication does not, however, deal with anything about thermally processing the respective components, wherein the
Kaneko Takeyasu
Kawase Yasunori
Miyazaki Hiroya
Nakamura Yuji
Crowell & Moring LLP
NSK Ltd.
Stormer Russell D.
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