Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
1999-12-23
2001-07-17
Herrmann, Allan D. (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C029S898130, C384S568000, C384S569000, C384S625000, C476S042000
Reexamination Certificate
active
06261203
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toroidal type continuously variable transmission which may be used as a transmission unit constituting a vehicular transmission or may be assembled as transmissions into various types of industrial machines.
2. Description of the Related Art
Study on the application of a toroidal type continuously variable transmission (as shown in
FIGS. 8 and 9
) into a transmission unit constituting a vehicular transmission progresses. An example of the toroidal type continuously variable transmission is disclosed in Japanese Utility Model Unexamined Publication Sho.62-71465.
In a conventional toroidal type continuously variable transmission shown in
FIGS. 8 and 9
, an input-side disk
2
is concentrically supported to an input shaft
1
. An output shaft
3
is also disposed concentrically with an input shaft
1
. An output-side disk
4
is fastened to the inner end of the output shaft
3
. In the inside of a casing in which the toroidal type continuously variable transmission is stored, there are located a pair of trunnions
6
,
6
. The trunnions
6
,
6
are swingable about their respective pivot shafts
5
,
5
respectively disposed at position 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.
8
. This physical relation is hereinafter referred to as “torsional relation”.
Each of the trunnions
6
,
6
located distant from the center axis of the input-side disk
2
and the output-side disk
4
is provided with each of the pivot shafts
5
,
5
on the outer side surfaces of the two end portions thereof to be perpendicular to a direction of the center axis thereof and be concentrically with each other. The base end portions of displacement shafts
7
,
7
are respectively supported in the central portions of the trunnions
6
,
6
and if the trunnions
6
,
6
are swung about the pivot shafts
5
,
5
respectively, the inclination angles of the displacement shafts
7
,
7
can be adjusted freely. On the peripheries of the two displacement shafts
7
,
7
supported on the two trunnions
6
,
6
, there are rotatably supported a plurality of power rollers
8
,
8
respectively. The power rollers
8
,
8
are respectively interposed between the inner surfaces
2
a
and
4
a
, opposed to each other, of the input-side disk
2
and the output-side disk
4
. The inner surfaces
2
a
and
4
a
are formed as concave surfaces which can be obtained by rotating an arc having the pivot shaft
5
as a center thereof. And, the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
, which are formed as spherical-shaped convex surfaces are respectively in contact with the inner surfaces
2
a
and
4
a.
Between the input shaft
1
and input-side disk
2
, there is interposed a pressure device
9
of a loading cam type, while the input-side disk
2
is elastically pressed toward the output-side disk
4
by the pressure device
9
. The pressure device
9
is composed of a cam plate
10
rotatable together with the input shaft
1
, and a plurality of (for example, four pieces of) rollers
12
,
12
which are respectively rollably held by a retainer
11
.
On one side surface (in
FIGS. 8 and 9
, on the left side surface) of the cam plate
10
, there is formed a drive-side cam face
13
being a curved surface which extends over the circumferential direction of the cam plate
10
. And, on the outer surface (in
FIGS. 8 and 9
, on the right side surface) of the input-side disk
2
, there is also formed a driven-side cam face
14
having a similar shape. The plurality of rollers
12
,
12
are each rotatably supported about their respective shafts which extend in the radial direction with respect to the center of the input shaft
1
.
The above-structured toroidal type continuously variable transmission operates in the following way. When the cam plate
10
is rotated with the rotation of the input shaft
1
, the drive-side cam face
13
presses the plurality of rollers
12
,
12
against the driven-side cam face
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 faces
13
and
14
are pressed against the plurality of rollers
12
,
12
, so that the input-side disk
2
is rotated. The rotation of the input-side disk
2
is transmitted through the plurality of power rollers
8
,
8
to the output-side disk
4
, so that the output shaft
3
fastened to the output-side disk
4
is rotated.
Next, a description will be given of a case of changing of a rotational speed ratio (speed change ratio) of the input and output shafts
1
and
3
. At first, when decelerating the rotational speed between the input shaft
1
and the output shaft
3
, the trunnions
6
,
6
are swung about the pivot shafts
5
,
5
in a predetermined direction, respectively. Then, the displacement shafts
7
,
7
are respectively inclined so that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
, as shown in
FIG. 8
, can be respectively contacted with a near-center portion on the inner surface
2
a
of the input-side disk
2
and with a near-outer-periphery portion on the inner surface
4
a
of the output-side disk
4
.
Also, on the other hand, when accelerating the rotational speed between the input and output shafts
1
and
3
, the trunnions
6
,
6
are respectively swung about the pivot shafts
5
,
5
in the opposite direction to the predetermined direction. Then, the displacement shafts
7
,
7
are respectively inclined so that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
, as shown in
FIG. 9
, can be respectively contacted with a near-outer-periphery portion on the inner surface
2
a
of the input-side disk
2
and a near-center portion on the inner surface
4
a
of the output-side disk
4
. When the inclination angles of the displacement shafts
7
,
7
are set in the middle of the inclination angles shown in
FIGS. 8 and 9
, then there can be at obtained an intermediate transmission ratio between the input and output shafts
1
and
3
.
A specific example of the toroidal type continuously variable transmission is shown in
FIGS. 10 and 11
. This transmission is disclosed in Japanese Utility Model Unexamined Publication No. Hei. 1-173552. As shown, an input-side disk
2
and an output-side disk
4
are rotatably supported around a cylindrical input shaft
15
with the aid of needle roller bearings
16
,
16
inserted therebetween. As shown in
FIGS. 12
to
14
in detail, each of the needle roller bearings
16
,
16
is constructed with a plurality of needle rollers
54
,
54
and cage-like window type retainers
55
for holding rollably those needle rollers
54
,
54
. In this case, the outer circumferential surface of the input shaft
15
serves as a cylindrical inner raceway
56
of the needle roller bearing
54
, and the inner circumferential surfaces of the input-side and output-side disks
2
,
4
serve as the outer raceway
57
of the needle roller bearing
54
.
A cam plate
10
is spline engaged with the outer peripheral surface of the end portion (in
FIG. 10
, the left end portion) of the input shaft
15
and is prevented, by a flange portion
17
, from moving in a direction away from the input-side disk
2
. Further the cam plate
10
and rollers
12
,
12
constitute a pressure device
9
of a loading cam type. The pressure device
9
, in accordance with the rotation of the input shaft
15
, rotates the input-side disk
2
while it is pressing against the input-side disk
2
toward the output-side disk
4
. An output gear
18
is coupled to the output-side disk
4
by means of keys
19
,
19
so that the output-side disk
4
and the output gear
18
are synchronously rotated.
A pair of trunnions
6
,
6
, in particular, their respective
Fujinami Makoto
Goto Nobuo
Higuchi Seiji
Itoh Hiroyuki
Shimizuya Masayoshi
Herrmann Allan D.
NSK Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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