Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
1998-07-01
2001-01-16
Fenstermacher, David (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C476S042000
Reexamination Certificate
active
06174257
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a toroidal type continuously variable transmission for use, for example, as an automatic transmission for an automobile. More particularly, it relates to improvements in a power roller and a thrust bearing for supporting the power roller.
2. Related Background Art
It has been studied to use a toroidal type continuously variable transmission as schematically shown in
FIGS. 8 and 9
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 side disc
2
supported concentrically with an input shaft
1
, and an output side disc
4
fixed to the end portion of an output shaft
3
disposed coaxially with the input shaft
1
. Trunnions
6
,
6
rockable about pivot shafts
5
,
5
transverse to the input shaft
1
and the output shaft
3
are provided inside a casing containing the toroidal type continuously variable transmission therein.
The trunnions
6
,
6
have the pivot shafts
5
,
5
provided on the outer sides of the opposite end portions thereof. Also, the base end portions of displacement shafts
7
,
7
are supported on the central portions of the trunnions
6
,
6
and the trunnions
6
,
6
are rocked about the pivot shafts
5
,
5
to thereby make the angles of inclination of the displacement shafts
7
,
7
adjustable. Power rollers
8
,
8
are rotatably supported around the displacement shafts
7
,
7
supported on the trunnions
6
,
6
. The power rollers
8
,
8
are held between the input side and output side discs
2
and
4
. The inner sides
2
a
and
4
a
of the input side and output side discs
2
and
4
which are opposed to each other have their cross-sections each forming a concave surface generated by rotating an arc centered on a pivot shaft
5
about the input shaft
1
or the output shaft
3
. The peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
are formed into spherical convex surfaces and bear against the inner sides
2
a
and
4
a.
A loading cam type pressing device
9
is provided between the input shaft
1
and the input side disc
2
, and the input side disc
2
is resiliently pressed toward the output side disc
4
by this pressing device
9
. The pressing device
9
is comprised of a cam plate
10
rotatable with the input shaft
1
, and a plurality of (e.g. four) rollers
12
,
12
held by a holder
11
. A cam surface
13
which is an uneven surface in a circumferential direction is formed on one side (the left side as viewed in
FIGS. 8 and 9
) of the cam plate
10
, and a similar cam surface
14
is formed on the outer side (the right side as viewed in
FIGS. 8 and 9
) of the input side disc
2
. The plurality of rollers
12
,
12
are supported for rotation about radial axes 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 cam surface
13
presses the plurality of rollers
12
,
12
against the cam surface
14
on the outer side of the input side disc
2
. As the result, the input side disc
2
is pressed against the power rollers
8
,
8
and at the same time, the input side disc
2
is rotated on the basis of the pressing of the pair of cam surfaces
13
,
14
against the plurality of rollers
12
,
12
. This rotation of the input side disc
2
is transmitted to the output side disc
4
through the power rollers
8
,
8
to thereby rotate the output shaft
3
fixed to the output side disc
4
.
When the rotational speed ratio (the transmission gear ratio) between the input shaft
1
and the output shaft
3
is to be changed and deceleration is first to be done between the input shaft
1
and the output shaft
3
, the trunnions
6
,
6
are rocked about the pivot shafts
5
,
5
and the displacement shafts
7
,
7
are inclined so that as shown in
FIG. 8
, the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
may bear against the portion toward the center of the inner side
2
a
of the input side disc
2
and the portion toward the outer periphery of the inner side
4
a
of the output side disc
4
, respectively. When conversely, acceleration is to be done, the displacement shafts
7
,
7
are inclined so that as shown in
FIG. 9
, the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
may bear against the portion toward the outer periphery of the inner side
2
a
of the input side disc
2
and the portion toward the center of the inner side
4
a
of the output side disc
4
, respectively. If the angles of inclination of the displacement shafts
7
,
7
are made medium between
FIGS. 8 and 9
, a medium transmission gear ratio will be obtained between the input shaft
1
and the output shaft
3
.
Further,
FIGS. 10 and 11
of the accompanying drawings show a 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 side disc
2
and an output side disc
4
are rotatably supported around an input shaft
15
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. 10
) of the input shaft
15
, and is prevented from moving away from the input side disc
2
by a flange portion
17
. The cam plate
10
and rollers
12
,
12
together constitute a loading cam type pressing device
9
for rotating the input side disc
2
while pressing it toward the output side disc
4
on the basis of the rotation of the input shaft
15
. An output gear
18
is coupled to the output side disc
4
by keys
19
,
19
so that the output side disc
4
and the output gear
18
may rotate in synchronism with each other. The output gear
18
and a gear or the like, not shown, meshing with the output gear
18
together constitute a power output mechanism to output the rotation of the output disc.
Pivot shafts
5
,
5
provided at the opposite end portions of a pair of trunnions
6
,
6
are supported on a pair of yokes
20
,
20
for rocking movement and displacement in an axial direction (the front to back direction as viewed in
FIG. 10
or the left to right direction as viewed in FIG.
11
). The pair of yokes
20
,
20
are in the form of metallic plates having sufficient rigidity, and have circular holes formed in the central portions thereof fitted on support posts
24
a
,
24
b
secured to the inner surface of a casing
22
or the side of a cylinder case
23
provided in the casing
22
, whereby they are supported for rocking movement and displacement in the axial direction of the pivot shafts
5
,
5
. Circular support holes
25
,
25
are formed in the opposite end portions of the yokes
20
,
20
, and the pivot shafts
5
,
5
are supported in the support holes
25
,
25
by radial needle bearings
27
,
27
provided with outer races
26
,
26
. On the basis of these constructions, the trunnions
6
,
6
are supported in the casing
22
for rocking movement about the pivot shafts and displacement in the axial direction of the pivot shafts
5
,
5
.
Displacement shafts
7
,
7
are supported in circular holes
52
,
52
formed in the intermediate portions of the trunnions
6
,
6
supported in the casing
22
in the manner described above. These displacement shafts
7
,
7
have support shaft portions
28
,
28
and pivot shaft portions
29
,
29
parallel to each other and eccentric with respect to each other. The support shaft portions
28
,
28
are rockably supported inside the circular holes
52
,
52
through radial needle bearings
30
,
30
. Power rollers
8
,
8
are rotatably supported around the pivot shaft portions
29
,
29
through radial anti-friction bearings such as radial needle bearings
31
,
31
.
The pair of displacement shafts
Fujinami Makoto
Goto Nobuo
Imanishi Takashi
Kato Hiroshi
Mitamura Nobuaki
Fenstermacher David
NSK Ltd.
Vorys Sater Seymour and Pease LLP
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