Rolling bearing unit with rotating speed detector

Details Rolling bearing unit with rotating speed detector Rolling bearing unit with rotating speed detector

1997-06-23

2001-04-03

Raevis, Robert (Department: 2856)

Measuring and testing

Simulating operating condition

Marine

C073S493000, C073S494000, C324S166000, C384S448000

Reexamination Certificate

active

06209389

ABSTRACT:

FIELD OF THE INVENTION
This invention is related to a rolling bearing unit with rotating speed detector to rotatably support the vehicle wheels with respect to the suspension apparatus and to detect the rotating speed of the vehicle wheels.
DESCRIPTION OF THE PRIOR ART
Various constructions for a rolling bearing unit with rotating speed detector to detect rotating speed of a vehicle wheel are known up to now in order that the vehicle wheel is supported with respect to the suspension freely rotatably while an anti-lock brake system (ABS) or a traction control system (TCS) is controlled.
The rotating speed detector which is installed in the rolling bearing unit with rotating speed detector has a tone wheel which rotates with the vehicle wheel and a sensor which outputs a signal changing in proportion to the rotating speed of the tone wheel.
Various types of tone wheels and sensors are known up to now. The rotating speed detector of the passive type which uses the tone wheel made of magnetic material such that the voltage generated in the coil of the sensor changes according to the rotation of the tone wheel is used widely, because it does not use expensive components.
The passive type of the rotating speed detector which comprises an annular sensor to make the output of the sensor larger as shown, for example, in HATSUMEI KYOKAI Technical Report Publication No. 94-16051 is known in the prior art.
FIGS. 4 and 5
show the rolling bearing unit with rotating speed detector as disclosed in this Technical Report Publication.
A hub
1
has an axially outer end portion which is formed with a flange
2
for wheel fixture on its outer peripheral face, a mid-portion which is formed with an inner ring raceway
3
a
and a stepped portion
4
on its outer peripheral face, and an axially inner end portion which has an inner ring member
5
provided on its outer peripheral face.
The term “axially outer” in the specification means the outer side in a widthwise direction when installed in the vehicle; left in figures, and the term “axially inner” means the center side in a widthwise direction when installed in the vehicle; right in figures.
The inner ring member
5
is formed with an inner ring raceway
3
b
and externally fitted to the outer peripheral face of the hub
1
with an axially outer end face thereof abutted against the stepped portion
4
.
A male-threaded portion
6
is formed on the axially inner end portion of the hub
1
. The inner ring member
5
is fixed at a predetermined location on the outer peripheral face of the hub
1
by means of a nut
7
which is threaded onto the threaded portion
6
and tightened, thus constituting an inner ring assembly together with the hub
1
.
There is also the case where, instead of directly forming the inner ring raceway
3
a
on the outer peripheral face of the hub
1
, it is formed as an inner ring member (not shown) separate from the hub
1
, and externally fitted to the hub
1
together with the inner ring member
5
.
An outer ring member
8
located around the hub
1
has a mid-portion which is provided with an attachment portion
9
on an outer peripheral face thereof, for fixing the outer ring member
8
to a suspension unit (not shown).
An inner peripheral face of the outer ring member
8
is formed with outer ring raceways
10
a
,
10
b
opposite to the inner ring raceways
3
a
,
3
b
respectively.
A plurality of rolling elements
11
, specifically balls, are respectively provided between the two inner ring raceways
3
a
,
3
b
and the pair of outer ring raceways
10
a
,
10
b
, so that the hub
1
is rotatable inside the outer ring member
8
.
In the case of a hub unit for heavy vehicles, tapered rollers are used for the rolling elements instead of the balls shown
FIGS. 4 and 5
.
A seal ring
12
is fitted between the inner peripheral face at the axially outer end of the outer ring member
8
, and the outer peripheral face of the hub
1
, to cover the opening at axially outer end of the space in which the plurality of rolling elements
11
are provided between the inner peripheral face of the outer ring member
8
and the outer peripheral face of the hub
1
.
A tone wheel
13
has a base end portion (left end in
FIGS. 4 and 5
) which is externally fixed to a portion on an axially inner end of the inner ring member
5
which is spaced away from the inner ring raceway
3
b.
The tone wheel
13
is made of magnetic metal plate such as steel plate, and is entirely annular or short-cylindrical. The tone wheel
13
comprises a smaller-diameter section
14
and a larger-diameter section
15
that are continuous through a stepped section
16
and concentric with each other. This kind of tone wheel
13
is fixed to and supported by the inner ring member
5
, such that the larger-diameter section
15
is fitted around the outer peripheral face on the axially inner end portion of the inner ring member
5
, so that the stepped section
16
comes in contact with the axially inner edge of the inner ring member
5
. Therefore, the smaller-diameter section
14
is supported so that it is concentric with the inner ring member
5
.
There are several through holes
17
formed around the smaller-diameter section
14
at equal intervals in the circumferential direction to form a first cut-out section where the magnetic characteristics change alternately at equal intervals in the circumferential direction.
These through holes
17
are identical in shape and specifically rectangular shaped to extend in the axial direction (left and right in FIGS.
4
and
5
). Only the cross section of one of the through holes
17
is shown in figures for simplicity.
An opening portion at the axially inner end portion of the outer ring member
8
is covered with a cover
18
made for example by deep drawing a metal sheet such as stainless steel plate, or aluminum alloy plate into the form of a bottomed cylinder.
An annular synthetic resin block
21
in which is embedded an annular sensor
20
is fixed and retained within the cylindrical portion
19
of the cover
18
. This sensor
20
comprises a permanent magnet
22
, a stator
23
made of magnetic material such as steel plate, and a coil
24
. By embedding the permanent magnet
22
, stator
23
and coil
24
in the synthetic resin block
21
, the sensor
20
can be made generally annular.
Of these components which make up the sensor
20
, the permanent magnet
22
is formed in a generally annular or circular ring shape and magnetized so that its magnetic orientation is in the radial direction. The inner peripheral face of this permanent magnet
22
is faced, through a small clearance
25
, to the outer peripheral face of a base portion of the smaller diameter section
14
of the tone wheel
13
where the through holes
17
are not formed.
The stator
23
is formed in a generally annular shape and has a radially outer cylindrical section
26
and a radially inner cylindrical section
27
connected to each other through a radial section in a substantially J-shaped cross section. The inner peripheral face on the axially outer end of the radially outer cylindrical section
26
of the stator
23
is very near or comes in contact with the outer peripheral face of the permanent magnet
22
. Moreover, the inner peripheral face of the radially inner cylindrical section
27
of the stator
23
is faced to a tip portion of the tone wheel
13
where the through holes
17
are formed.
Furthermore, a plurality of notches
28
with an axial open end are formed in a second cut-out section around the radially inner cylindrical section
27
of the stator
23
, so that they are located around the cylindrical section
27
circumferentially with the same pitch as the through holes
17
. This pitch is referred to as center-angle pitch. Accordingly, the radially inner cylindrical section
27
is formed so that it is comb-toothed.
The coil
24
is formed by winding a conductive wire around a non-magnetic bobbin
29
so that it is annular shaped, and it is located on the inner peripheral side of the radially outer cylindrical section
26
of t

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