Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2000-12-29
2001-12-11
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C324S207250
Reexamination Certificate
active
06328476
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a rolling bearing unit with an encoder which is used for rotatably supporting an automobile wheel with respect to the suspension, as well as for detecting the rotation speed of the wheel.
DESCRIPTION OF THE PRIOR ART
Various kinds of rolling bearing units with an encoder have been known in the art which detects the rotation speed of the wheel in order to rotatably support the wheel with respect to the suspension, while in order to be able to control an anti-lock brake system (ABS) or traction control system (TCS). For example,
FIG. 1
shows a structure as disclosed in U.S. Pat. No. 5,622,437.
The suspension has a knuckle
1
with a mount hole
2
formed therein, and a stationary race or outer race
3
is fitted into the interior of the mount hole
2
. On the inner diameter side of the outer race
3
, a pair of inner rings
6
a
,
6
b
are provided in a concentric relation with the outer race
3
, respectively, to form a rotatable race
5
together with a hub
4
. Outer ring raceways
7
in double rows are formed on the inner peripheral surface of the outer race
3
while inner ring raceways
8
are formed on the outer peripheral surface of the inner rings
6
a
,
6
b
, and rolling members such as balls
9
or conical rollers are provided between the outer ring raceways
7
and the inner ring raceways
8
, so that the rotatable race
5
is rotatably supported inside the outer race
3
.
A constant velocity joint
11
has an output shaft
12
which is spline-connected to the central hole
10
of the hub
4
to rotatably drive the rotatable race
5
. In addition, onto the outer periphery at one end of the inner ring
6
b
(right one in
FIG. 1
, an encoder of permanent magnet
13
is fixed and supported through a slinger
14
. This slinger
14
is formed in a generally annular shape with L-shaped cross section and fixedly fitted onto the end of the inner ring
6
b.
The permanent magnet
13
is magnetized in the axial directions (left and right directions in FIG.
1
). The magnetized directions are alternately changed with a uniform pitch. Accordingly, S-poles and N-poles are circumferentially alternately arranged with a uniform interval on the side surface of the permanent magnet
13
.
In addition, a seal ring
15
is fixedly fitted into the inner peripheral surface at one end of the outer race
3
, and has seal lips the tip end of which comes in sliding contact with the slinger
14
in the whole circumference.
The mount hole
2
, which is a support section of the outer race
3
with reference to the knuckle
1
, has a portion which a support plate
16
in a generally annular shape is fixed to and supported by. The support plate
16
has a portion to which a sensor unit
35
is mounted. The sensor unit
35
has elements such as Hall ICs embedded therein to change the output corresponding to the magnetic flux change. With the sensor unit
35
mounted to the portion of the support plate
16
, the detection section provided on the tip end of the sensor unit
35
faces the side surface of the permanent magnet
13
with a small clearance therebetween.
When using the rolling bearing unit with the encoder as mentioned above, a vehicle wheel is mounted to the rotatable flange
17
provided on the outer peripheral surface of the hub
4
. As the vehicle wheel rotates, the permanent magnet
13
fixedly fitted onto the inner ring
6
b
rotates, and then the output of the sensor facing the permanent magnet
13
changes. The frequency of the changing output of the sensor is proportional to the rotation speed of the vehicle wheel. Therefore, the output signals of the sensor is sent to a controller, not shown in the figure, it is possible to obtain the rotation speed of the wheel and to adequately control the ABS or TCS.
In the case of the prior art rolling-bearing unit with encoder that is constructed and functions as described above, the shape of the support plate
16
, that separates the permanent magnet
13
of the encoder from the outside, is complex. Therefore, the manufacturing cost of a rolling-bearing unit with encoder that includes this support plate
16
becomes expensive. Also, since this support plate
16
does not rotate even when the wheel rotates, there is little seal effect by this support plate
16
. This is because there is unavoidably a large gap around the tip end of the sensor unit
35
supported by the support plate
16
.
Regardless of the existence of this support plate
16
, it is easy for rain water and the like that is brought in by the wheel to get into the area where the permanent magnet
13
is located. As a result, there is a possibility that foreign matter, such as magnetic dust, could adhere to the permanent magnet
13
and lower the accuracy of the rotation speed detection device.
For a rolling-bearing unit that supports the wheel so that it can rotate freely with respect to the suspension device, it is possible to construct it such that the rotating race is provided on the outer race side, other than that the rotating race is provided on the inner race side as in the case of the prior art construction shown in FIG.
1
. However, for the prior art construction shown in
FIG. 1
, if the outer race is used as the rotating race, it is difficult to obtain adequate seal performance.
For example, a rolling-bearing unit having the rotation speed detector which is constructed as shown in
FIG. 1
installed therein and using the outer race as the rotating race, has been disclosed in U.S. Pat. No. 5,451,869. However, in the construction disclosed in U.S. Pat. No. 5,451,869, since the outer race is the only member that rotates and is located further outside in the radial direction than the encoder, it is difficult to effectively prevent matter from adhering to the encoder.
SUMMARY OF THE INVENTION
An object of the present invention, taking the problems as mentioned above into consideration, to provide a rolling bearing unit with encoder in low-cost construction wherein the outer race is the rotating race, and making it possible to effectively prevent foreign matter from penetrating into the encoder section.
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patent: 5476272 (1995-12-01), Hixson, II
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patent: 5611545 (1997-03-01), Nicot
patent: 5622437 (1997-04-01), Alff
patent: 5640087 (1997-06-01), Alff
patent: 5642042 (1997-06-01), Goossens et al.
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patent: 42 06 910 (1993-07-01), None
patent: 691 11 879 (1995-08-01), None
patent: 5-19265 (1993-05-01), None
Hosoda Masahiro
Miyazaki Hiroya
Nakamura Yuji
Ouchi Hideo
Crowell & Moring LLP
Hannon Thomas R.
NSK Ltd.
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