Planetary gear transmission systems or components – Nonplanetary variable speed or direction transmission... – Nonplanetary transmission is friction gearing
Reexamination Certificate
1999-07-27
2001-03-20
Wright, Dirk (Department: 3681)
Planetary gear transmission systems or components
Nonplanetary variable speed or direction transmission...
Nonplanetary transmission is friction gearing
Reexamination Certificate
active
06203466
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to improvements in a continuously variable transmission apparatus incorporating therein, for example, a toroidal type continuously variable transmission utilized as a transmission for an automobile, and realizes compact structure capable of securing the durability of the constituent members of the toroidal type continuously variable transmission.
2. Related Background Art
For example, it has been studied to use a toroidal type continuously variable transmission as schematically shown in
FIGS. 6 and 7
of the accompanying drawings as a transmission for an automobile. This toroidal type continuously variable transmission, as disclosed, for example, in Japanese Laid-Open Utility Model Application No. 62-71465, has an input disc
2
supported concentrically with an input shaft
1
, and has an output disc
4
fixed to the end portion of an output shaft
3
disposed concentrically with the input shaft
1
. Inside a casing containing the toroidal type continuously variable transmission, there are provided trunnions
6
,
6
pivotatally moved about pivots
5
,
5
on axes transverse to the input shaft
1
and the output shaft
3
.
That is, the pivots
5
,
5
of each trunnion are provided coaxially with each other on the outer sides of the opposite end portions of the trunnion. Also, the base end portions of displaceable shafts
7
,
7
are supported on the central portions of the trunnions
6
,
6
, and the trunnions
6
,
6
are pivotally moved about the pivots
5
,
5
, whereby the angles of inclination of the displaceable shafts
7
,
7
are made adjustable. Power rollers
8
,
8
are rotatably supported around the displaceable shafts
7
,
7
supported on the trunnions
6
,
6
. These power rollers
8
,
8
are sandwiched between the input and,output discs
2
and
4
. The inner sides
2
a
and
4
a
of these input and output discs
2
and
4
which are opposed to each other have their cross-sections forming concave surfaces obtained with arcs centering about the pivots
5
rotated about the center axes of the discs. The peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
which are formed into spherical convex surfaces, are made to bear against the above-mentioned inner sides
2
a
and
4
a
, respectively.
A loading cam type pressing device
9
is provided between the input shaft
1
and the input disc
2
, and by this pressing device
9
, the input disc
2
can be resiliently pressed toward the output disc
4
. This pressing device
9
is comprised of a cam plate
10
rotated with the input shaft
1
, and a plurality of (e.g. four) rollers
12
held by a holder
11
. A cam surface
13
which is an uneven surface extending in the circumferential direction is formed on one side (the left side as viewed in
FIGS. 6 and 7
) of the cam plate
10
, and a similar cam surface
14
is also formed on the outer side (the right side as viewed in
FIGS. 6 and 7
) of the input disc
2
. The plurality of rollers
12
,
12
are supported for rotation about radial shafts relative to the center of the input shaft
1
.
When during the use of the toroidal type continuously variable transmission constructed as described above, the cam plate
10
rotates with the rotation of the input shaft
1
, the plurality of rollers
12
are pressed against the cam surface
14
formed on the outer side of the input disc
2
by the cam surface
13
. As a result, the input disc
2
is pressed against the plurality of power rollers
8
,
8
and at the same time, on the basis of the pair of cam surfaces
13
,
14
and the plurality of rollers
12
,
12
being urged against each other, the input disc
2
is rotated. The rotation of this input disc
2
is transmitted to the output disc
4
through the plurality of power rollers
8
,
8
, whereby the output shaft
3
fixed to this output disc
4
is rotated.
When the rotational speed ratio (transmission gear ratio) between the input gear
1
and the output gear
3
is to be changed and deceleration is to be effected between the input shaft
1
and the output shaft
3
, the trunnions
6
,
6
are pivotally moved about the pivots
5
,
5
and the displaceable shafts
7
,
7
are inclined so that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
may bear against that portion of the inner side
2
a
of the input disc
2
which is toward the center thereof and that portion of the inner side
4
a
of the output disc
4
which is toward the outer periphery thereof, as shown in FIG.
6
. When conversely, acceleration is to be effected, the trunnions
6
,
6
are pivotally moved and the displaceable shafts
7
,
7
are inclined so that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
may bear against that portion of the inner side
2
a
of the input disc
2
which is toward the outer periphery thereof and that portion of the inner side
4
a
of the output disc
4
which is toward the center thereof, as shown in FIG.
7
. Also, if the angle of inclination of the displaceable shafts
7
,
7
is made medium between
FIGS. 6 and 7
, a medium transmission gear ratio will be obtained between the input shaft
1
and the output shaft
3
.
FIGS. 8 and 9
of the accompanying drawings show a more specific example of the toroidal type continuously variable transmission described in the microfilm of Japanese Utility Model Application No. 63-69293 (Japanese Laid-Open Utility Model Application No. 1-173552). An input disc
2
and an output disc
4
are rotatably supported around a tubular input shaft
15
through needle bearings
16
and
16
, respectively. Also, a cam plate
10
is spline-engaged with the outer peripheral surface of an end portion (the left end portion as viewed in
FIG. 8
) of the input shaft
15
and blocks the movement away from the input disc
2
by a flange portion
17
. This cam plate
10
and rollers
12
,
12
together constitute a pressing device
9
for rotating the input disc
2
on the basis of the rotation of the input shaft
15
while pressing it toward the output disc
4
. An output gear
18
is coupled to the output disc
4
by keys
19
,
19
so that the output disc
4
and the output gear
18
may be rotated in synchronism with each other.
The opposite end portions of a pair of trunnions
6
,
6
are supported on a pair of support plates
20
,
20
for pivotal movement and displacement in the axial direction thereof (the front to back direction as viewed in
FIG. 8
, and the left to right direction as viewed in FIG.
9
). Displaceable shafts
7
,
7
are supported in circular holes
21
,
21
formed in the intermediate portions of the trunnions
6
,
6
. These displaceable shafts
7
,
7
have support shaft portions
22
,
22
and pivotal support shaft portions
23
,
23
parallel to each other and eccentric with respect to each other. The support shaft portions
22
,
22
are rotatably supported inside the circular holes
21
,
21
through radial needle bearings
24
,
24
. Also, power rollers
8
,
8
are rotatably supported around the pivotal support shaft portions
23
,
23
through discrete radial needle bearings
25
,
25
.
The pair of displaceable shafts
7
,
7
are provided at positions opposite by 180° with respect to the input shaft
15
. Also, the directions in which the pivotal support shaft portions
23
,
23
of these displaceable shafts
7
,
7
are eccentric with respect to the support shaft portions
22
,
22
are the same direction (left and right converse directions as viewed in
FIG. 9
) with respect to the direction of rotation of the input and output discs
2
and
4
. Also, the direction of eccentricity is a direction substantially orthogonal to the direction of disposition of the input shaft
15
. Accordingly, the power rollers
8
,
8
are supported for some displacement in the direction of disposition of the input shaft
15
. As the result, even when the power rollers
8
,
8
tend to be displaced in the axial direction of the input shaft
15
(the left to right direction as viewed in
FIG. 8
, and the front
Imanishi Takashi
Ishikawa Kouji
Itoh Hiroyuki
Machida Hisashi
Miyata Shinji
NSK Ltd.
Vorys Sater Seymour and Pease LLP
Wright Dirk
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