Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2001-04-19
2004-08-17
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S486000
Reexamination Certificate
active
06776531
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a transmission and a rolling bearing with seal plate for that transmission, and more particularly to improvements in the transmission (including a transaxle) for an automobile, truck, or a special kind of vehicle such as a tractor or fork lift, and to improvements in the rolling bearing with seat plate that is installed in that kind of transmission. The transmission which is the object of this invention, includes a manual transmission, as well as all kinds of automatic transmission such as planetary-gear type, belt type and toroidal type.
2. Description of the Related Art
An example of an automatic transmission that has a rolling bearing with seal plate installed in it as disclosed in U.S. Pat. No. 4,309,916, is shown in FIG.
3
. In the manual transmission, simply shown in
FIG. 3
, lubrication oil (transmission oil)
25
is stored in a casing
24
, and an input shaft
26
and output shaft
27
are arranged in the casing
24
such that they are concentric with each other and can freely rotate relative to each other. Moreover, there is also a transmission shaft
28
located inside the casing
24
such that it is parallel with respect to the input shaft
26
and output shaft
27
. The input shaft
26
, output shaft
27
and transmission shaft
28
are supported respectively by a rolling bearing
1
with seal plate such that they can rotate freely.
A drive gear
29
, which is a power transmission member on the drive side, is supported on the input shaft
26
. Also, on the output shaft
27
, there are follower gears
30
a
to
30
d
, which are power transmission members on the follower side, and they are each supported by a synchro mesh mechanism (not shown in the figure). During operation, only one of the aforementioned follower gears
30
a
to
30
d
rotates together with the output shaft
27
, and the other follower gears rotate relative to the output shaft
27
.
Moreover, at respective sections of the transmission shaft
28
which face the drive gear
29
and follower gears
30
a
to
30
d
, there are transmission gears
31
a
to
31
e
which are supported such that they rotate freely with the transmission shaft
28
. These transmission gears
31
a
to
31
c
are made to mesh with the drive gear
29
and follower gears
30
a
to
30
d
directly or by way of an idler gear
32
for moving back.
As described above, a plurality of rotating shafts and many gears are assembled in the automobile transmission. These rotating shafts and gears are supported by rolling bearings, such as ball bearings or cylindrical roller bearings, such that they rotate freely with respect to the housing and support shaft. On the inside of this kind of transmission, there is a lot of foreign matter, such as grinding scraps or grinding agent, that is caused in processing the gears or housing etc., and adheres to and remains on the gears or housing, or as abrasive material that is generated in the section where the gears mesh during operation. When this kind of foreign matter gets inside the rolling bearing, indentations are formed by the foreign matter on the rolling contact surfaces, and these indentations make it easier for the surfaces to become damaged due to fatigue. Therefore, conventionally, a rolling bearing
1
with seal plate, as shown in
FIG. 4
, is used as the rolling bearing for use in conditions where there exist much metallic foreign matter as described above.
This rolling bearing
1
with seal plate comprises: an inner race
3
having inner ring raceway
2
of the deep-groove type formed around its outer peripheral surface in the center in the axial direction (left and right direction in FIG.
4
), an outer race
5
arranged concentric with the inner race
3
and having an outer ring raceway
4
of the deep-groove type formed around its inner peripheral surface in the middle in the axial direction, and a plurality of rolling bodies or balls
6
located between the inner ring raceway
2
and outer ring raceway
4
such that they can rotate freely. These balls
6
are supported inside a plurality of pockets
8
which are formed in a retainer
7
, such that each ball
6
can rotate freely itself in each pocket
8
. Instead of the balls
6
, shown in the example in the figure, it is also possible to use cylindrical or tapered rollers as the rolling bodies.
Moreover, attachment grooves
9
are formed around the inner peripheral surface on both ends of the outer race
5
, and the outer peripheral edges of the seal plates
10
are attached to the attachment grooves
9
. These seal plates
10
are generally circular shaped and comprise a circular-shaped metal core
11
that is made of a metal plate such as a steel plate and an elastic member
12
such as a rubber-like elastomer which is reinforced by the metal core
11
. The outer peripheral edge of the elastic member
12
is made to protrude outward in the radial direction (up and down direction in
FIG. 4
) only a little from the outer peripheral edge of the metal core
11
, and this protruding section fitted into and attached to the attachment groove
9
.
On the other hand, the inner peripheral edge of the elastic member
12
is made to protrude sufficiently inward in the radial direction from the inner peripheral edge of the metal core
11
to form a seal lip
13
in the protruding section. In addition, seal grooves
14
are formed on the outer peripheral surface on both ends of the inner race
3
such that they are defined by an inner wall surface
15
and outer wall surface
16
, and the tip edge of this seal lip
13
comes in contact with the inner-wall surface
15
of seal grooves
14
. Here, the tip edge of this seal lip
13
is forked with reference to the axial direction, such that even when the inner race
3
or outer race
5
is displaced in the axial direction, the tip edge of this seal lip
13
is always in sliding contact with at least one of the inner wall surface
15
and outer wall surface
16
of the seal groove
14
.
With the rolling bearing
1
with seal plate, constructed as described above, relative rotation of the member around which the inner race
3
is attached and the member inside which the outer race
5
is attached is allowed by the rolling of the balls
6
. Moreover, the pair of seal plates
10
, whose outer peripheral edges are fitted into the inner peripheral surface on both ends of the outer race
5
, prevents the grease that is filled inside the space
17
where the balls
6
are located, from leaking out, and also prevents foreign matter on the outside such as dirt, oil, or water from getting into the space
17
where the balls
6
are located.
In the case of the seal plate
10
comprising the metal core
11
and the elastic member
12
made of a rubber-like elastomer or the like, not only is the cost high, but it is also difficult to make the seal plate
10
more lightweight and reusable (recyclable). In other words, weight of the seal plate
10
is increased by the amount of the metal core
11
that is used to reinforce the elastic member
12
. In addition, since the elastic member
12
is attached to the metal core
11
, the manufacturing cost increases, and the seal plate
10
becomes more difficult to reuse.
In the case of just reducing the manufacturing cost, it is considered to be possible to use inexpensive nitrile rubber (NBR) as the elastic member
12
. However, when NBR is used in the high-temperature conditions in an automobile transmission or in an environment with constant contact with oil, the material soon becomes hard and in poor condition, and thus there is a possibility that a proper seal cannot be maintained over a long period of time.
On the other hand, in the case of using an acrylic rubber or fluorine-contained rubber which comparatively does not easily become hard or degrade in high-temperature environment, the cost and weight increase and reusability becomes difficult, so from the aspect of protecting the environment, it is not preferred.
On the other hand, when the seal plate is made of synthetic resin,
Takeda Masao
Tsuchida Yuki
Uchiyama Takahiko
Hannon Thomas R.
NSK Ltd.
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