Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2002-03-06
2004-02-17
Footland, Lenard A. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
Reexamination Certificate
active
06692153
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a wheel support bearing assembly for an automotive vehicle or the like and, more particularly, to the wheel support bearing assembly integrated with a magnetic encoder for detection of the number of revolution of a wheel.
2. Description of the Prior Art
As shown in
FIG. 23
, the wheel support bearing assembly is well known, which includes generally cylindrical inner and outer members
101
and
102
positioned one radially inside the other with an annular space defined therebetween, dual rows of rolling elements
103
interposed between the inner and outer members
101
and
102
and rollingly movably positioned within the annular space, an annular sealing device
105
accommodated within and positioned at one of opposite ends of the annular space, and an annular magnetic encoder
106
integrated together with the sealing device
105
. This known wheel support bearing assembly is disclosed in, for example, the Japanese Laid-open Patent Publication No. 6-281018.
In this known wheel support bearing assembly, the sealing device
105
includes generally L-sectioned first and second annular sealing plates
107
and
108
press-fitted onto an outer periphery of the inner member
101
and into a bore of the outer member
102
, respectively, and an annular sealing strip
109
secured to the second annular sealing plate
108
. The first sealing plate
107
is generally referred to as a slinger. The annular magnetic encoder
106
employed therein is in the form of an elastic member (also referred to as a multi-pole magnet)
111
made of a vulcanizable elastic material mixed with a powdered magnetic material and is bonded by vulcanization to the first sealing plate
107
. The multi-pole magnet
111
has a plurality of magnetic N- and S-poles alternately defined therein in a direction circumferentially thereof and is operatively associated with a magnetic sensor
110
disposed in face-to-face relation with the multi-pole magnet
111
to detect the number of revolutions of the wheel rotatably supported by the wheel support bearing assembly.
With the known wheel support bearing assembly of the structure discussed above, it has been found that in the event of ingress of foreign matter such as, for example, stones or rocks into a working gap delimited between the multi-pole magnet
111
and the magnetic sensor
110
, the multi-pole magnet
111
and, hence, the magnetic encoder
106
may be impaired, resulting in failure to detect the number of revolutions of the wheel properly.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide a wheel support assembly designed to prevent foreign matter from being caught in between the multi-pole magnet and the magnetic sensor and, if not at all, to render the multi-pole magnet to be little damaged.
In order to accomplish the foregoing object, the present invention in accordance with a first aspect thereof provides a wheel support bearing assembly which includes an outer member; an inner member positioned inside the outer member to define an annular space therebetween; at least one row of rolling element accommodated within the annular space and operatively interposed between the inner and outer members; a sealing device for sealing an open end of the annular space; and a protective cover made of a non-magnetic material.
The sealing device includes first and second annular sealing plates fitted to different members out of the inner and outer members. Each of the first and second sealing plate includes a generally cylindrical wall and a radial wall assembled together to represent a generally L-shaped section, the first and second sealing plates being positioned within the annular space in face-to-face relation with each other. The first sealing plate is fitted to a rotating member out of the inner and outer members with the radial wall of the first sealing plate positioned on one side adjacent an exterior of the bearing assembly. An annular multi-pole magnet having a plurality of different magnetic poles alternating in a direction circumferentially thereof is fitted to the radial wall of the first sealing plate. On the other hand, the second sealing plate includes a side sealing lip, slidingly engaged with the radial wall of the first sealing plate and opposedly extending radial sealing lips slidingly engaged with the cylindrical wall of the first sealing plate. The cylindrical wall of the second sealing plate is positioned adjacent a slight distance from a free edge of the radial wall of the first sealing plate with a slight radial gap defined therebetween. The protective cover referred to above is disposed exteriorly of the multi-pole magnet and positioned adjacent thereto with a predetermined air gap defined therebetween so that a number of revolution can be detected through the protective cover.
The multi-pole magnet referred to above may be in the form of a sintered magnet, or may be made of an elastic member, such as a rubber, or a plastics material mixed with a powdered magnetic material.
According to the first aspect of the present invention, since the protective cover is used and positioned exteriorly of the multi-pole magnet forming a part of the magnetic encoder so that the number of revolution can be detected through the protective cover, any possible “biting” of foreign matter in between the magnetic sensor for the detection of the number of revolutions and the multi-pole magnet can be prevented by the presence of the protective cover. Also, even if the foreign matter is caught in between the protective cover and the magnetic sensor, the foreign matter does not directly contact the multi-pole magnet and, therefore, the multi-pole magnet is hardly damaged. Also, since the protective cover is positioned adjacent the multi-pole magnet forming the part of the magnetic encoder with the predetermined air gap intervening therebetween, rotation of the multi-pole magnet will not be disturbed by the protective cover. Yet, since the protective cover is made of the non-magnetic material, detection of the magnetic encoder by the magnetic sensor will not be disturbed undesirably.
In the first aspect of the present invention, the protective cover may be fitted to one of the first and second members that serves as a stationary member. With this design, the protective cover does not rotate and, since the protective cover and the magnetic sensor, both held stationary, confront with each other, the foreign matter can advantageously be prevented from entering in between the protective cover and the magnetic sensor during rotation.
Preferably, a slight labyrinth gap is defined between the protective cover and one of the first and second members that serves as a rotating member. The presence of the labyrinth seal is effective to avoid any possible ingress of dusts into the annular space between the inner and outer members through between the protective cover and the rotating member without the rotation of the rotating member being disturbed.
Also, a sealing lip may be provided, which is integrated with a radial edge of the protective cover and held in sliding contact with an end face of one of the inner and outer members that serves as a rotating member. The provision of the protective cover with the sealing lip is effective to avoid any possible ingress of the dusts into the annular space between the inner and outer members through between the protective cover and the rotating member.
The protective cover may be fitted to an outer periphery of the outer member. In this case, since the protective cover is mounted on the outer periphery of the outer member, unlike the case in which the protective cover is mounted on an inner periphery of the outer member, any possible space for disposition of the protective cover at an open end of the annular space between the inner and outer members can be dispensed with and a sufficient sectional height of the sealing device including the first and second sealing plate can advantageously be s
Norimatsu Takayuki
Ohtsuki Hisashi
Footland Lenard A.
NTN Corporation
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