Continuously variable transmission

Details Continuously variable transmission Continuously variable transmission

1998-08-03

2001-03-27

Fenstermacher, David (Department: 3682)

Friction gear transmission systems or components

Friction gear includes idler engaging facing concave surfaces

Toroidal

C476S042000

Reexamination Certificate

active

06206801

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a continuously variable transmission which can continuously change the transmission ratio between an input shaft and an output shaft, in various industrial machines including automobiles.
2. Related Background Art
Various types of continuously variable transmissions are used and one of them is a toroidal type continuously variable transmission. This is a transmission in which the opposed surfaces of an input disc mounted on an input shaft and an output disc mounted on an output shaft are formed by toroidal surfaces. A power roller is disposed between these toroidal surfaces, and by changing the rocked state (angle) thereof, the transmission gear ratio between the input shaft and the output shaft can be changed.
FIGS. 1 and 2
of the accompanying drawings show a conventional toroidal type continuously variable transmission described in Japanese Utility Model Laid-Open Application No. 1-173552. An input side disc
2
and an output side disc
4
are rotatably supported around a tubular input shaft
15
through needle bearings
16
. 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. 1
) of the input shaft
15
and is prevented from moving away from the input side disc
2
by a flange portion
17
. This cam plate
10
and rollers
12
together constitute a pressing device
9
of the loading cam type for rotating the input side disc
2
, on the basis of the rotation of the input shaft
15
while pressing the input side disc
2
toward the output side disc
4
. An output gear
18
is coupled to the output side disc
4
through a key
19
so that the output side disc
4
and the output gear
18
may be rotated synchronously with each other. The output gear
18
is rotatably supported by a bearing
41
.
The opposite end portions of a pair of trunnions
6
are supported by a pair of supporting plates
20
for rocking about an axis X—X and for displacement in X—X direction (the front to back direction as viewed in
FIG. 1
or the left to right direction as viewed in FIG.
2
). Displacement shafts
7
are rotatably supported in circular holes
23
formed in the intermediate portions of the trunnions
6
through needle bearings
24
. Also, power rollers
8
are rotatably supported around pivot shaft portions
22
through needle bearings
25
.
The pair of displacement shafts
7
are provided at opposite side positions relative to the input shaft
15
, and the pivot shaft portions
22
are eccentric relative to support shaft portions
21
. The direction of eccentricity is the same direction (the right to left direction as viewed in
FIG. 2
) in the rotational direction of the input side and output side discs
2
and
4
and a direction substantially orthogonal to the lengthwise direction of the input shaft
15
. Accordingly, the power rollers
8
are somewhat displaceable in the lengthwise direction of the input shaft
15
.
Thrust ball bearings
26
and thrust needle bearings
27
are provided between the outer side of the power rollers
8
and the inner side of the intermediate portions of the trunnions
6
. The thrust ball bearings
26
support a load in a thrust direction applied to the power rollers
8
, and yet permit the rotation thereof. The thrust needle bearings
27
support a thrust load applied from the power rollers
8
to outer races
30
, and yet permit the pivot shaft portions
22
and the outer races
30
to rock about the support shaft portions
21
.
Driving pistons
37
are secured to the outer peripheral surfaces of the intermediate portions of driving rods
36
coupled to one end portion (the left end portion as viewed in
FIG. 2
) of the trunnions
6
, and are fitted in an oil-tight manner in driving cylinders
38
. Consequently, the rotation of the input shaft
15
is transmitted to the input side disc
2
through the pressing device
9
, and the rotation of this input side disc
2
is transmitted to the output side disc
4
through the pair of power rollers
8
, and further the rotation of this output side disc
4
is output via the output gear
18
.
When the rotational speed ratio between the input shaft
15
and the output gear
18
is to be changed, the pair of driving pistons
37
are displaced in opposite directions. With this, the pair of trunnions
6
are displaced in opposite directions (for example, the lower power roller
8
in
FIG. 2
to the right and the upper power roller
8
to the left). As the result, the direction of a force in the tangential direction acting on the portions of contact between the peripheral surfaces
8
a
of these power rollers
8
and the inner sides
2
a
and
4
a
of the input side disc
2
and the output side disc
4
changes. With this change, the trunnions
6
rock in opposite directions about a pivot shaft X—X pivotally supported by the supporting plates
20
.
When the transmission of the rotational force is thus effected between the input shaft
15
and the output gear
18
, the power rollers
8
are displaced axially of the input shaft
15
on the basis of the resilient deformation of each constituent member, and the displacement shafts
7
are slightly pivotally moved about the support shaft portions
21
. As the result, the outer sides of the outer races of the thrust ball bearings
26
and the inner sides of the trunnions
6
are displaced relative to each other.
Further, there is known a structure (double cavity type) in which to increase transmittable torque, as shown in
FIG. 3
of the accompanying drawings, input side discs
52
A,
52
B and output side discs
54
A,
54
B are disposed at the opposite ends of an input shaft
65
to be parallel to one another with respect to the direction of transmission of power. These output side discs
54
A,
54
B are mounted around the input shaft
65
through bearings
66
to thereby make the rotation thereof relative to the input shaft
65
and the displacement thereof in the axial direction of the input shaft
65
possible. The input side discs
52
A,
52
B are supported for axial movement relative to the input shaft
65
and for rotation in a circumferential direction with the input shaft. An output gear
68
a
is rotatably supported on the intermediate portion of the input shaft
65
, and the output side discs
54
A,
54
B are spline-engaged with the opposite end portions of a cylindrical portion provided in the central portion of the output gear
68
a.
One (the left as viewed in
FIG. 3
) input side disc
52
A has its back abutted against a loading nut
89
through a belleville spring
95
having a great resilient force (in some case, abutted directly against the loading nut) to thereby substantially prevent the axial displacement thereof relative to the input shaft
65
. In contrast, the input side disc
52
B opposed to a cam plate
60
is supported on the input shaft
65
by a ball spline
90
A for axial displacement, and a belleville spring
91
and a thrust needle bearing
92
are provided in series between the back (the right surface as viewed in
FIG. 3
) of the input side disc
52
B and the front surface (the left surface as viewed in
FIG. 3
) of the cam plate
60
. The belleville spring
91
serves to impart a pre-load to the portions of contact between the inner sides
52
a
,
54
a
of the discs
52
A,
52
B;
54
A,
54
B and the peripheral surfaces
58
a
of power rollers
58
, and the thrust needle bearing
92
serves to permit the relative rotation of the input side disc
52
B and the cam plate
60
during the operation of a pressing device
59
.
As shown in
FIG. 3
, in a toroidal type continuously variable transmission of the so-called double cavity type, one or both of the input side discs
52
A,
52
B opposed to the cam plate
60
are supported for axial displacement relative to the input shaft
55
by ball splines
90
A,
90
B. The purposes of this are:
(i) To completely synchronize the rotations of the input side discs
52
A,
52
B with each other; and
(ii) To endow the function of item (i) above,

Affiliated with

Also associated with

Rating

Continuously variable transmission does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Continuously variable transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuously variable transmission will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2506785