Abrading – Abrading process – Ring – tube – bushing – sleeve – or cylinder abrading
Reexamination Certificate
2001-02-13
2003-06-03
Rachuba, M. (Department: 3682)
Abrading
Abrading process
Ring, tube, bushing, sleeve, or cylinder abrading
C451S052000, C451S063000
Reexamination Certificate
active
06572452
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement in input and output discs for a toroidal type continuously variable transmission used as a transmitting unit of a transmission of an automobile or transmissions for various industrial machines, and a method for manufacturing or working such discs.
2. Related Background Art
Use of various toroidal type continuously variable transmissions as shown in
FIGS. 5 and 6
as transmission for automobiles has been investigated. In such a toroidal type continuously variable transmission, for example, as disclosed in Japanese Patent Application Laid-Open No. 11-141637 (1999), an input disc
2
is supported coaxially with an input shaft
1
, and an output disc
4
is secured to an end of an output shaft
3
disposed coaxially with the input shaft
1
. Within a casing containing the toroidal type continuously variable transmission, there are provided trunnions
6
rocked around pivot shafts
5
arranged at twisted positions with respect to the input shaft
1
and the output shaft
3
.
The trunnions
6
are provided at their outer surfaces with the pivot shafts
5
at both ends thereof. Further, the trunnions
6
support proximal ends of displacement shafts
7
at their centers so that inclination angles of the displacement shafts
7
can be adjusted by rocking the trunnions
6
around the pivot shafts
5
. Around the displacement shafts supported by the trunnions
6
, power rollers
8
are rotatably supported. The power rollers
8
are pinched between the input disc
2
and the output disc
4
. Opposed inner surfaces
2
a,
4
a
of the input and output discs
2
,
4
have concave surfaces obtained by rotating an arc or a similar curved line around the input and output shafts
1
,
3
respectively. Peripheral surfaces
8
a
of the power rollers
8
formed as spherical convex surfaces abut against the inner surfaces
2
a,
4
a.
Between the input shaft
1
and the input disc
2
, there is provided an urging device
9
such as a loading cam which serves to elastically bias the input disc
2
toward the output disc
4
. The urging device
9
comprises a cam plate
10
rotated together with the input shaft
1
, and a plurality (for example, four) of rollers
12
held by a holder
11
. One surface (left surface in
FIGS. 5 and 6
) of the cam plate
10
has a cam surface
13
as a circumferential uneven surface, and an outer surface (right surface in
FIGS. 5 and 6
) of the input disc
2
has a similar cam surface
14
. The plurality of rollers
12
are supported for rotation around axes radially to the center of the input shaft
1
.
In use of the toroidal type continuously variable transmission having the above-mentioned construction, when the cam plate
10
is rotated as the input shaft
1
is rotated, the plurality of rollers
12
are urged against the cam surface
14
provided on the outer surface of the input disc
2
by means of the cam surface
13
. As a result, the input disc
2
is urged against the plurality of power rollers
8
, and, at the same time, the input disc
2
is rotated due to the engagement between the cam surfaces
13
,
14
and the plurality of rollers
12
. The rotation of the input disc
2
is transmitted to the output disc
4
via the plurality of power rollers
8
, thereby rotating the output shaft
3
secured to the output disc
4
.
In a case where a rotational speed ratio (transmission ratio) between the input shaft
1
and the output shaft
3
is changed, first of all, when speed reduction is achieved between the input shaft
1
and the output shaft
3
, by rocking the trunnions
6
around the pivot shafts
5
, as shown in
FIG. 5
, the displacement shafts
7
are inclined so that the peripheral surfaces
8
a
of the power rollers
8
abut against a portion near the center on the inner surface
2
a
of the input disc
2
and a portion near the periphery on the inner surface
4
a
of the output disc
4
, respectively. On the other hand, when speed increase is achieved, by rocking the trunnions
6
around the pivot shafts
5
, as shown in
FIG. 6
, the displacement shafts
7
are inclined so that the peripheral surfaces
8
a
of the power rollers
8
abut against a portion near the periphery on the inner surface
2
a
of the input disc
2
and a portion near the center on the inner surface
4
a
of the output disc
4
, respectively. If the inclination angles of the displacement shafts
7
are selected to have middle values between FIG.
5
and
FIG. 6
, a middle transmission ratio can be obtained between the input shaft
1
and the output shaft
3
.
Fundamental structure and function of the toroidal type continuously variable transmission are as mentioned above, and a more concrete construction of such a toroidal type continuously variable transmission is well-known, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 11-141637. Further, a toroidal type continuously variable transmission of so-called double cavity type in which two input discs and two output discs are disposed side by side in a power transmitting direction to increase a power to be transmitted is also well-known, for example, as disclosed in Japanese Patent Applications Laid-Open Nos. 1-229158 (1989) and 4-69439 (1992).
Since the more concrete construction of such a toroidal type continuously variable transmission is well-known and does not directly relate to the gist of the present invention, explanation thereof will be omitted. However, in any case, configurations and features (surface roughness) of the inner surfaces
2
a,
4
a
of the input and output discs
2
,
4
must be formed correctly as desired. The reason is that the inner surfaces
2
a,
4
a
must transmit great torque while abutting against the peripheral surfaces
8
a
of the power rollers
8
and the contacting conditions between the surfaces
2
a,
4
a
and
8
a
are rolling contact including slip due to spin.
Accordingly, in order to extend a service life of the surfaces
2
a,
4
a,
8
a
against rolling fatigue and to allow great torque to be transmitted, the contact portions of the surfaces
2
a,
4
a,
8
a
must have traction oil films each having a proper thickness. The accuracy of configurations of the inner surfaces
2
a,
4
a
are required for optimizing the contacting conditions between the surfaces
2
a,
4
a
and
8
a,
and the regulation of surface roughness of the surfaces
2
a,
4
a,
8
a
to the desired value is required for optimizing the thickness of the traction oil films.
To this end, conventionally, there has been proposed a finishing operation in which the inner surfaces
2
a,
4
a
of the input and output discs
2
,
4
are polished by a grindstone having a desired feature (surface roughness) to finish the configurations and features (surface roughness) of the inner surface
2
a,
4
a
as desired. The grindstone which can be used in such a finishing operation is disclosed, for example, in Japanese Patent Application Laid-Open No. 8-252770 (1996).
FIGS. 7 and 8
show a grindstone
15
and a method for effecting a finishing operation on an inner surface
16
a
of a disc
16
used as an input disc or an output disc of a toroidal type continuously variable transmission by using this grindstone
15
, disclosed in the above patent gazette.
A working surface
17
of the grindstone
15
is an arc surface having a sectional configuration corresponding to a sectional configuration of the inner surface
16
a.
When the inner surface
16
a
is polished by such a grindstone
15
, the disc
16
is rotated around a center axis shown by the dot and chain line a in
FIG. 8
while urging the working surface
17
against the inner surface
16
a.
In this case, a shoe is slidingly contacted with a portion of a cylindrical surface
18
formed in outer periphery of the disc
16
at a position opposed to the grindstone
15
in a radial direction, thereby preventing radial displacement of the disc
16
(out-of-center during the working) in opposition to the urging force of the grindstone
15
.
In case of the
Hatase Seiichiro
Tanaka Masami
Miles & Stockbridge P.C.
NSK Ltd.
Rachuba M.
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