Toroidal-type continuously variable transmission

Details Toroidal-type continuously variable transmission Toroidal-type continuously variable transmission

2000-09-22

2002-08-27

Herrmann, Allan D. (Department: 3682)

Friction gear transmission systems or components

Friction gear includes idler engaging facing concave surfaces

Toroidal

C476S040000

Reexamination Certificate

active

06440034

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toroidal-type continuously variable transmission for use as a transmission unit for a car transmission or as a transmission for various kinds of industrial machines and, in particular, to such toroidal-type continuously variable transmission which is improved in the durability thereof as well as in the stability of the speed change operation thereof.
2. Description of the Related Art
Conventionally, it has been studied to use such a toroidal-type continuously variable transmission as shown in
FIGS. 4 and 5
as a transmission unit for a car transmission. In the conventional toroidal-type continuously variable transmission, for example, as disclosed in JP-A-62-71465U, an input side disk
2
is supported concentrically with an input shaft
1
, while an output side disk
4
is fixed to the end portion of an output shaft
3
which is disposed concentrically with the input shaft
1
. In the interior portion of a casing in which the toroidal-type continuously variable transmission is stored, there are disposed trunnions
6
,
6
which can be respectively swung about their associated pair of pivot shafts
5
,
5
which are respectively set at positions along an imaginary plane that is perpendicular to an imaginary line connecting the respective axes of the input and output shafts
1
and
3
, and distanced from the intersection of the imaginary plane and imaginary line, as shown in FIG.
4
. This physical relation is hereinafter referred to as “torsional relation (torsional position)”.
That is, in the case of the trunnions
6
,
6
, the pivot shafts
5
,
5
are arranged on the outer surfaces of the two end portions of the respective trunnions
6
,
6
in such a manner that the pivot shafts
5
,
5
are concentric with each other. The base end portions of displacement shafts
7
,
7
are supported on the respective middle portions of the trunnions
6
,
6
and, by swinging the trunnions
6
,
6
about their respective pivot shafts
5
,
5
, the inclination angles of the displacement shafts
7
,
7
can be freely adjusted. On the peripheries of the displacement shafts
7
,
7
respectively supported on the trunnions
6
,
6
, there are rotatably supported a plurality of power rollers
8
,
8
. And, the plurality of power rollers
8
,
8
are respectively held by and between the mutually opposing inner surfaces
2
a
,
4
a
of the input side and output side disks
2
,
4
. The mutually opposing inner surfaces
2
a
,
4
a
each has a cross section formed as a concave surface which can be obtained by rotating an arc with the pivot shaft
5
as the center thereof. On the other hand, the power rollers
8
,
8
respectively have peripheral surfaces
8
a
,
8
a
each of which is formed as a spherically convex surface. And, the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
are respectively contacted with the inner surfaces
2
a
,
4
a.
Between the input shaft
1
and the input side disk
2
, there is interposed a pressure device
9
of a loading cam type. Thus, the input side disk
2
can be elastically pushed toward the output side disk
4
by the pressure device
9
. The pressure device
9
comprises a cam plate
10
rotatable together with the input shaft
1
, and a plurality of rollers
12
,
12
(for example, four rollers) which are respectively held by a retainer
11
. On one side surface (in
FIGS. 4 and 5
, the left side surface) of the cam plate
10
, there is formed a drive-side cam surface
13
which comprises a curved surface extending in the circumferential direction of the cam plate
10
. Further, on the outer surface (in
FIGS. 4 and 5
, the right side surface) of the input side disk
2
there is formed a driven-side cam surface
14
which is similar in shape to the drive-side cam surface
13
. And the plurality of rollers
12
,
12
are supported in such a manner that they can be freely rotated about their respective axes extending in the radial direction with respect to the center of the input shaft
1
.
When the above-structured toroidal-type continuously variable transmission is in operation, in case where the cam plate
10
is rotated due to the rotation of the input shaft
1
, the drive-side cam surface
13
of the cam plate
10
presses the plurality of rollers
12
,
12
against the driven-side cam surface
14
formed on the outer surface of the input side disk
2
. As a result of this, the input side disk
2
is pressed against the plurality of power rollers
8
,
8
and, at the same time, the drive-side and driven-side cam surfaces
13
,
14
and the plurality of rollers
12
,
12
are pressed against each other, thereby causing the input side disk
2
to be rotated. And, the rotation of the input side disk
2
is transmitted to the output side disk
4
through the plurality of power rollers
8
,
8
, with the result that the output shaft
3
fixed to the output side disk
4
can be rotated.
Of cases in which the rotation speed ratio (transmission ratio) between the input shaft
1
and output shaft
3
is to be changed, at first, when decreasing the rotation speed ratio between the input shaft
1
and output shaft
3
, the trunnions
6
,
6
may be swung about their respective pivot shafts
5
,
5
in a given direction. And, the displacement shafts
7
,
7
are inclined in such a manner that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
, as shown in
FIG. 4
, can be respectively contacted with the near-center portion of the inner surface
2
a
of the input side disk
2
and with the near-outer-periphery portion of the inner surface
4
a
of the output side disk
4
. On the other hand, when increasing the rotation speed ratio, the trunnions
6
,
6
may be swung about their respective pivot shafts
5
,
5
, in the opposite direction. And, the displacement shafts
7
,
7
are inclined in such a manner that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
, as shown in
FIG. 5
, can be respectively contacted with the near-outer-periphery portion of the inner surface
2
a
of the input side disk
2
and with the near-center portion of the inner surface
4
a
of the output side disk
4
. In case where the inclination angles of the displacement shafts
7
,
7
are set in the middle of the inclination angles in
FIGS. 4 and 5
, there can be obtained a middle rotation speed ratio between the input shaft
1
and output shaft
3
.
Now,
FIGS. 6 and 7
show an example of a more specific structure of a toroidal-type continuously variable transmission which is disclosed in JP-A-1-173552U. In this structure, an input side disk
2
and an output side disk
4
are rotatably supported on the peripheries of a circular-pipe-shaped input shaft
15
through their respective needle roller bearings
16
,
16
. Also, a cam plate
10
is spline engaged with the outer peripheral surface of the end portion (in
FIG. 6
, the left end portion) of the input shaft
15
, while a collar portion
17
prevents the cam plate
10
from moving in a direction in which it parts away from the input side disk
2
. And, the cam plate
10
and rollers
12
,
12
cooperate together in forming a pressure device
9
of a loading came type which, in accordance with the rotation of the input shaft
15
, rotates the input side disk
2
toward the output side disk
4
while pressing the input side disk
2
. And, an output gear
18
is connected to the output side disk
4
through keys
19
,
19
, whereby the output side disk
4
and output gear
18
can be rotated in synchronism with each other.
In the pair of trunnions
6
,
6
, the two end portions of the respective trunnions
6
,
6
are supported on a pair of support plates
20
,
20
in such a manner that they can be swung as well as can be shifted in the axial direction thereof (that is, in
FIG. 6
, in the front and back direction; and, in
FIG. 7
, in the right and left direction). That is, between the outer peripheral surfaces of pivot shafts
5
,
5
fixedly secured to the two end portions of the respective trunnio

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