Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
1999-09-08
2001-07-03
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C324S207250
Reexamination Certificate
active
06254276
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is related to a rolling bearing unit with a rotational speed sensor, which is utilized to rotatably support a road wheel with reference to a suspension apparatus while detecting the rotational speed of the road wheel.
The road wheel is rotatably supported by a rolling bearing unit with reference to a suspension apparatus. In addition, the rotational speed of the road wheel must be detected in order to control an anti-lock braking system (ABS) and traction control system (TCS). Accordingly, recently the rolling bearing unit with rotational speed sensor, that is the rolling bearing unit having a rotational speed sensor installed therein, is broadly used to rotatably support the road wheel while detecting the rotational speed of the road wheel.
Japanese Utility Model Publication JITSUKAI HEI No. 7-31539 discloses one example of the prior art structures of the rotational speed sensor, which is also referred to as rpm detector in this specification, for use in such an object. An object of this publication is to provide a rolling bearing unit with rotation speed sensor wherein it is possible to take out only the rotation speed sensor from the hub cap for exchange and maintenance, to make short the axial size of the bearing unit, and to stabilize the sensor performance.
The rolling bearing unit of this publication comprises an inner ring member
202
(see
FIGS. 77-79
) onto the outer peripheral surface of which a pulser ring
204
is fixed fitted, the inner ring member
202
being fitted to a hub
201
at its end, and pressed by a nut
203
for fixing, an outer ring member
205
to which a hub cap
209
is attached, the hub cap
209
having a bottomed recess portion
209
a
enclosing the nut
203
, a flanged portion
209
b
extending radially outward from the end of the bottomed recess portion
209
a
, an engagement portion
209
c
, and a cylindrical portion
209
d.
The engagement portion
209
c
is formed at the end of the flanged portion
209
b
to abut the end face of the outer ring member
205
. The cylindrical portion
209
d
extends axially from the engagement portion
209
c
to be fitted into the end of the outer ring member
205
.
Removably fixed to the flanged portion
209
b
of the hub cap
209
is a sensor mount member
211
to which a rotation member detecting sensor
210
is integrally connected. The sensor mount portion
211
is positioned in the stepped space
214
defined by the bottomed recess portion
209
a
and the flanged portion
209
b.
The inner ring member
202
has a mount portion
201
a
for fixing a road wheel, and a raceway
202
a
on its peripheral surface, and functions as a rotating shaft.
The outer ring member
205
has a mount portion
205
a
for connecting to a vehicle body, and a raceway on its inner peripheral surface. Rolling members are provided between the hub
201
and the outer ring member
205
. Provided at one end of the hub is a pulser ring
204
which faces the rotation number detection sensor
210
with a slight clearance between them, and is fitted onto the outer peripheral surface of the inner ring member
202
.
In this structure, a pair of bolts and nuts
12
,
13
are used to securely fix a sensor
10
to a cover
9
of the rolling bearing unit (see e.g.
FIG. 3
of the publication). This step is carried out in the assembling site of the rolling bearing unit with rotational speed sensor but inconvenient to need a long process time. In addition, the disengagement and engagement of the bolts and nuts for repairing the rotational speed sensor in the rolling bearing unit are also troublesome. This leads to cost-up in the production and repair.
U.S. Pat. No. 4,946,295 which is incorporated in the present specification by reference, discloses another example of the bearing unit with rpm detector where the sensor is easily-engaged and disengaged with and from the bearing unit for easy inspection and repair. No special tool is used to install the sensor at the end of the stationary outer ring. However, no seal device is installed in this structure to protect the encoder and sensor from outside. Specifically, the seal ring
10
in this structure is used for isolating the space for installing the rolling members
3
from outside, but not for isolating the encoder and sensor from outside. Accordingly, for example, when it rained, water drops may be kept attached to the clearance between the encoder
19
and sensor
8
, which may lead to damages of the encoder and/or sensor if the automobile is started with the attached water drops frozen.
JP Patent Publication TOKUKAI HEI No. 9-1964945 discloses another example of the bearing unit with rpm detector, where the holder
26
with the sensor
12
a
embedded therein can be easily installed and removed with respect to the cover
23
fixed to the outer ring
2
a
without any special tool. However, some improvements are required in assembling the bearing unit with rpm detector. Specifically the cylindrical support body
27
must be placed in alignment with the holder
26
in phase in a circumferential direction. Therefore, the holder must often be rotated inside the cylindrical support body, but due to the presence of the elastically compressed O-ring on the cylindrical support body, the force to rotate the holder is substantially large to easily worsen the assembly performance of the bearing unit with rpm detector. In addition to the assembly performance, the performance of the rotational speed sensor must be taken into consideration with respect to the installation of the holder into the cover of the bearing unit.
The mechanism of the rotational speed sensor is detailed later referring to
FIGS. 73
to
76
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a rolling bearing unit with rotational speed sensor in which the engagement and disengagement of the sensor to the cover is carried out easily and instantly to reduce the cost.
Another object of the present invention is to provide a rolling bearing unit with rotational speed sensor in which the sensor holder is sealingly mounted to the cover of the bearing unit with the assembly performance of the holder into the cover improved.
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Mitsue Naoki
Morita Kouichi
Ouchi Hideo
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Hannon Thomas R.
NSK Ltd.
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