Toroidal type continuously variable transmission

Details Toroidal type continuously variable transmission Toroidal type continuously variable transmission

2000-10-26

2004-01-27

Joyce, William C. (Department: 3682)

Friction gear transmission systems or components

With friction enhancing fluid

C476S040000

Reexamination Certificate

active

06682457

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement in a toroidal type continuously variable transmission used as a transmission for a motor vehicle, for example, in order to realize a structure which can transmit great power and has sufficient endurance by adequately supplying oil to a power transmitting portion as needed.
2. Related Background Art
Application of a toroidal type continuously variable transmission as schematically shown in
FIGS. 8 and 9
to a transmission of a motor vehicle has been investigated. For example, as disclosed in Japanese Utility Model Application Laid-Open No. 62-71465, in the toroidal type continuously variable transmission, an input side disc
2
is coaxially supported with an input shaft
1
, and output side disc
4
is secured to an end of an output shaft
3
coaxially disposed with the input shaft
1
. Within a casing containing the toroidal type continuously variable transmission, trunnions
6
, which rock around pivot shafts
5
located at positions twisted with respect to the input shaft
1
and the output shaft
3
, are disposed between the input side disc
2
and the output side disc
4
in an axial direction.
That is to say, the trunnions
6
are provided at their outer surfaces with the pivot shafts
5
, which are coaxial with each other. Further, proximal ends of displacement shafts
7
are supported on intermediate portions of the trunnions
6
so that inclination angles of the displacement shafts
7
can be adjusted by rocking the trunnions
6
around the pivot shafts
5
. Power rollers
8
are rotatably supported around the displacement shafts
7
supported by the trunnions
6
. The power rollers
8
are pinched between opposed inner surfaces
2
a
and
4
a
of the input and output side discs
2
and
4
. Each of the inner surfaces
2
a
,
4
a
has, in section, a concave surface obtained by rotating an arc around the pivot shaft
5
. Peripheral surfaces
8
a
of the power rollers
8
having spherical convex surfaces are contacted with the inner surfaces
2
a
,
4
a.
An urging device
9
of loading cam type is disposed between the input shaft
1
and the input side disc
2
so that the input side disc
2
can be elastically biased toward the output side disc
4
by the urging device
9
. 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
rotatably held by a holder
11
. A cam surface
13
made concave and convex alternately in a circumferential direction is formed on one side surface (right side surface in
FIGS. 8 and 9
) of the cam plate
10
, and a cam surface
14
having a similar configuration is formed on an outer surface (left side surface in
FIGS. 8 and 9
) of the input side disc
2
. The plurality of rollers
12
are supported for rotation around axes oriented radially with respect to the centerline 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 cam surface
13
urges the plurality of rollers
12
against the cam surface
14
formed on the outer surface of the input side disc
2
. As a result, the input side disc
2
is urged against the plurality of power rollers
8
and, at the same time, the input side disc
2
is rotated due to the urging between the cam surfaces
13
,
14
and the plurality of rollers
12
. The rotation of the input side disc
2
is transmitted to the output side disc
4
through the plurality of power rollers
8
, thereby rotating the output shaft
3
secured to the output side disc
4
.
In a case where a rotational speed ratio (transmission ratio) between the input shaft
1
and the output shaft
3
is changed, when deceleration (speed reduction) is effected between the input shaft
1
and the output shaft
3
, the trunnions
6
are rocked in predetermined directions around the pivot shafts
5
. And, the displacement shafts
7
are inclined so that, as shown in
FIG. 8
, the peripheral surfaces
8
a
of the power rollers
8
abut against a portion near the center of the inner surface
2
a
of the input side disc
2
and a portion near the peripheral of the inner surface
4
a
of the output side disc
4
, respectively. On the other hand, when acceleration (speed increase) is effected, the trunnions
6
are rocked in opposite directions around the pivot shafts
5
. And, the displacement shafts
7
are inclined so that, as shown in
FIG. 9
, the peripheral surfaces
8
a
of the power rollers
8
abut against a portion near the peripheral of the inner surface
2
a
of the input side disc
2
and a portion near the center of the inner surface
4
a
of the output side disc
4
, respectively. When the inclination angles of the displacement shafts
7
are selected to an intermediate value between FIG.
8
and
FIG. 9
, an intermediate transmission ratio can be obtained between the input shaft
1
and the output shaft
3
.
FIGS. 10 and 11
show an example of a more concrete toroidal type continuously variable transmission described in Japanese Utility Model Application Laid-Open No. 1-173552. An input side disc
2
and an output side disc
4
are rotatably supported around a cylindrical input shaft
15
via needle bearings
16
. Further, a cam plate
10
is spline-connected to an outer peripheral surface of the input shaft
15
at an end thereof (left end in FIG.
10
), and the cam plate is prevented from being shifted away from the input side disc
2
by means of a flange
17
. The cam plate
10
and rollers
12
constitute an urging device
9
for rotating the input side disc
2
while urging it toward the output side disc
4
as the input shaft
15
is rotated. An output gear
18
is joined to the output side disc via keys
19
so that the output side disc
4
and the output gear
18
are rotated in a synchronous manner.
Pivot shafts
5
provided on both ends of a pair of trunnions
6
are supported by a pair of support plates
20
for rocking movement and axial displacement (in a direction perpendicular to the plane of
FIG. 10 and a
left-and-right direction in FIG.
11
). Displacement shafts
7
are supported in circular holes
21
formed in intermediate portions of the trunnions
6
. The displacement shafts
7
have parallel and eccentric support shaft portions
22
, and pivot shaft portions
23
. The support shaft portions
22
are rotatably supported in the circular holes
21
via radial needle bearings
24
. Further, power rollers
8
are rotatably supported around the pivot shaft portions
23
via radial needle bearings
25
.
Incidentally, the pair of displacement shafts
7
are disposed at positions diametrically opposed with respect to input shaft
15
. Further, directions along which the pivot shaft portions
23
of the displacement shafts
7
are eccentric with respect to the support shaft portions
22
are the same directions (opposite directions in
FIG. 11
) with respect to the rotational directions of the input and output side discs
2
,
4
. Further, the eccentric directions are substantially perpendicular to the installation direction of the input shaft
15
. Accordingly, the power rollers
8
are supported for slight displacement in the axial direction (left-and-right direction in FIG.
10
and direction perpendicular to the plane of
FIG. 11
) of the input shaft
15
. As a result, even if the power rollers
8
tend to be displaced in the axial direction of the input shaft
15
due to elastic deformation of the constructural parts caused by a great load acting on the constructural parts during the rotational force transmitting condition, such displacement can be absorbed without applying great or excessive force to the various parts.
Further, thrust ball bearings
26
and thrust needle bearings
27
are disposed between the outer surfaces of the power rollers
8
and the inner surfaces of the intermediate portions of the trunnions
6
, and the thrust ball bearings
26
are located near the p

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