Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
2000-11-13
2003-10-28
Knight, Anthony (Department: 3676)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S562000, C277S571000, C384S448000, C384S486000
Reexamination Certificate
active
06637754
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a sealing device in a wheel bearing for an automobile or the like and, more particularly, to the sealing device of a kind integrated together with an encoder grid.
2. Description of the Prior Art
The wheel bearing including, as shown in
FIG. 37
, a sealing device
105
interposed between an inner member
101
and an outer member
102
rotatable to each other through a circular row of rolling elements
103
has been well known in the art. The sealing device
105
shown therein includes an encoder grid
106
integrated together therewith. In this connections see the Japanese Laid-open Patent Publication No. 6-281018. The prior art sealing device
105
includes generally L-sectioned first and second annular sealing plates
107
and
108
fitted respectively to the inner and outer members
101
and
102
with an elastically deformable sealing lip member
109
secured to the second annular sealing plate
108
so as to intervene between the first and second annular sealing plates
107
and
108
. The first annular sealing plate
107
is generally referred to as a slinger. The encoder grid
106
is made of an elastic material mixed with a powder of magnetic particles and is bonded by vulcanization to the first annular sealing plate
107
. This encoder grid
106
is of an annular configuration having a plurality of pairs of magnetically opposite poles alternating over the circumference thereof and is cooperable with a magnetic sensor
110
disposed externally in face-to-face relation with the encoder grid
106
for detection of the encoder grid
106
.
The first annular sealing plate
107
serving as the slinger and the inner member
101
serving as a rotatable member are engaged with each other under interference fit at an engagement interface
111
. However, it has been found that a small quantity of water often ingresses externally into the wheel bearing through the engagement interface
111
. Once water ingresses, the first and second annular sealing plates
107
and
108
gather rust, resulting a premature wear of the sealing lip member
109
. Also, the grease is prematurely degraded to such an extent as to result in reduction of the lifetime of the wheel bearing.
In view of the foregoing, it has been suggested to reconfigure the encoder grid
106
so that a portion of the elastic material forming the encoder grid
106
extends to an inner peripheral surface of the first annular sealing plate
107
to thereby increase the sealability at the engagement interface
111
. However, since the elastic material forming the encoder grid
106
is mixed with the powder of magnetic particles, not only becomes the encoder grid
106
expensive to manufacture, but a required sealing performance is difficult to attain. Also, formation of a relatively thick rubber layer at the engagement interface
111
between the first annular sealing plate
107
and the inner member
101
results in an insufficient engagement therebetween with the consequence that there is a high risk of the first annular sealing plate
107
being separated from the wheel bearing and/or displaced internally of the wheel bearing.
Although instead of the intervention of the elastic material the first annular sealing plate
107
may be made of a soft material to thereby increase the adherence, such soft material is normally of a non-magnetic nature and, therefore, the first annular sealing plate
107
made of such material will fail to provide a magnetic core for the encoder grid
106
, resulting in an insufficient density of magnetic fluxes.
The first annular sealing plate
107
may exhibit a sufficient resistance to rusting if it is made of magnetic stainless steel (for example, SUS
430
MA) of a kind having a resistance to rusting comparable to that of SUS
304
, rather than a generally utilized magnetic material such as SUS
430
of a kind lacking a sufficient resistance to rusting. The magnetic stainless steel referred to above may be SUS
430
MA consisting of a stainless steel such as SUS
430
mixed with niobium, Ni or the like to increase the resistance to rusting. As regards the magnetic flux density, SUS
430
MA is comparable to SUS
430
. However, not only is the magnetic stainless steel referred to above expensive, but even though such material is employed for the first annular sealing plate
107
, ingress of water cannot be sufficiently prevented, and therefore, reduction of the lifetime of the wheel bearing as a result of degradation of the grease in contact with water cannot be avoided sufficiently.
FIG. 38
illustrates another prior art wheel bearing. In this figure, components identical with or similar to those shown in
FIG. 37
are shown by like reference numerals used in FIG.
37
. The sealing device
105
shown in
FIG. 38
is shown as employed in the rolling bearing of a type having an inner race rotatable relative to an outer race. The sealing device
105
includes a slinger
107
press-fitted to an outer peripheral end face of the inner race
101
, a core metal
108
press-fitted to an inner peripheral end face of the outer race
102
in face-to-face relation with the slinger
107
, a sealing member
109
fitted to the core metal
108
and held in sliding contact with the slinger
107
, and a rubber magnet
106
bonded by vulcanization to the slinger
107
. The rubber magnet
106
referred to above is a pulse generating ring generally used for speed control of a vehicle such as, for example, an automobile. The slinger
107
is of a structure including an cylindrical body
107
a
having an outer edge formed integrally with a radial flange
107
b
that protrudes radially outwardly towards the outer race
102
. The core metal
108
is of a structure including a cylindrical body
108
a
press-fitted to the inner peripheral end face of the outer race
102
and formed integrally with an radial flange
108
b
that protrudes radially inwardly towards the inner race
101
from an inner end thereof adjacent the circular row of the rolling elements
103
. An outer end
108
aa
of the hollow cylindrical body
108
a
is slightly radially inwardly bent to accommodate the sealing member
109
.
The sealing device
105
of the structure shown in FIG.
38
and described above is mounted in position inside the rolling bearing in the manner which will now be described. After the sealing device
105
has been assembled separate and independent of the rolling bearing, the sealing device
105
is press-fitted into the rolling bearing with the slinger
107
mounted on the inner race
101
and the core metal
108
fitted inside the outer race
102
. During the press-fitting of the sealing device
105
, a plurality of the sealing devices
105
stacked on a support table
114
as shown in
FIG. 39
are delivered one by one into a chute by means of a handling unit of an automatic press-fitting machine and is then picked up to be press-fitted in the rolling bearing.
However, since the sealing device
105
shown in
FIG. 38
is of a design integrated together with the rubber magnet
106
, stacking on the support surface
114
(
FIG. 39
) the plural sealing devices
105
with the core metal
108
held in contact with the support surface
114
and with the slinger
107
, bonded by vulcanization with the corresponding rubber magnet
106
, positioned on one side of such core metal
108
remote from the support surface
114
results in contact of the rubber magnet
106
on the slinger
107
in one of the sealing devices
105
with the core metal
108
of the next adjacent sealing device
105
positioned immediately above such one of the sealing devices
105
. Considering that the rubber magnet
106
exerts a magnetic force of attraction, the rubber magnet
106
in one of the sealing devices
105
attracts the core metal
108
in the next adjacent sealing device
105
positioned immediately above such one of the sealing devices
105
and, accordingly, a trouble often occurs in delivering the sealing devices
105
one by one by means of the handl
Funahashi Eiji
Kametaka Koji
Niki Motoharu
Norimatsu Takayuki
Ohtsuki Hisashi
Knight Anthony
NTN Corporation
Peavey E
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