Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
2001-09-18
2004-10-05
Bucci, David A. (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C384S470000, C384S614000
Reexamination Certificate
active
06800046
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a toroidal-type continuously variable transmission which is used, for example, as a transmission unit in an automatic transmission for a vehicle or as a transmission for various kinds of industrial machines.
As a transmission unit for use in an automatic transmission of a vehicle, such a toroidal-type continuously variable transmission as generally shown in
FIGS. 6 and 7
has been studied and enforced in some sectors of a car industry. This toroidal-type continuously variable transmission is structured such that, for example, as disclosed in Japanese Utility Model Unexamined Publication No. Sho.62-71645, an input side disk
2
is supported concentrically with an input shaft
1
and an output side disk
4
is fixed to the end portion of an output shaft
3
. On the inner surface of a casing in which a toroidal-type continuously variable transmission is stored, or, on support brackets disposed within the casing, there are disposed trunnions
6
,
6
which can be respectively swung about their associated pivot shafts
5
,
5
disposed at twisted positions with respect to the input shaft
1
and output shaft
3
.
That is, the trunnions
6
,
6
are disposed as follows. Namely, their respective pivot shafts
5
,
5
are disposed on the outer surfaces of the two end portions of the trunnions
6
,
6
in such a manner that they are concentric with each other as well as extend at right angles or substantially at right angles to the direction of the input and output shafts
1
and
3
. Also, there are disposed displacement shafts
7
,
7
on their respective trunnions
6
,
6
in such a manner that the base end portions of the displacement shafts
7
,
7
are supported on the central portions of their respective trunnions
6
,
6
. In case where the trunnions
6
,
6
are swung about their associated pivot shafts
5
,
5
, the inclination angles of the displacement shafts
7
,
7
can be adjusted freely. Further, on the peripheries of the displacement shafts
7
,
7
supported on their respective trunnions
6
,
6
, there are supported power rollers
8
,
8
in such a manner that they can be rotated. And, the power rollers
8
,
8
are held by and between the input side and output side disks
2
,
4
. The mutually opposing inner surfaces
2
a
,
4
a
of the input side and output side disks
2
,
4
are each formed in a concave surface whose section shows an arc shape with a point on the center axis of the pivot shaft
5
as a center thereof. And, the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
, which are respectively formed as spherically convex surfaces, are contacted with the inner surfaces
2
a
,
4
a
of the input side and output side disks
2
,
4
.
Also, between the input shaft
1
and input side disk
2
, there is interposed a pressing device
9
of a loading cam type in such a manner that the pressing device
9
pushes elastically the input side disk
2
toward the output side disk
4
. The pressing device
9
is composed of a cam plate
10
rotatable together with the input shaft
1
and a plurality of (for example,
4
) rollers
12
,
12
respectively held by a retainer
11
. On one side surface (in
FIGS. 6 and 7
, on the left side surface) of the cam plate
10
, there is formed a cam surface
13
which is a concavo-convex surface extending in the circumferential direction of the cam plate
10
. On the outer surface (in
FIGS. 6 and 7
, on the right side surface) of the input side disk
2
as well, there is formed a cam surface
14
which is similar to the cam surface
13
. And, the plurality of rollers
12
,
12
are supported in such a manner that they can be rotated about an axis extending in a radial direction with respect to the center of the input shaft
1
.
When the above-structured toroidal-type continuously variable transmission is in use, in case where the cam plate
10
is rotated with the rotation of the input shaft
1
, the cam surface
13
presses the plurality of rollers
12
,
12
against the 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, in accordance with the mutually pressing actions between the pair of cam surfaces
13
,
14
and the plurality of power rollers
8
,
8
, the input side disk
2
is rotated. And, the rotation of the input side disk
2
is transmitted through the plurality of power rollers
8
,
8
to the output side disk
4
, thereby rotating the output shaft
3
which is fixed to the output side disk
4
.
Now, description will be given below of a case where the rotation speeds of the input shaft
1
and output shaft
3
are changed. First, to decelerate the rotation speed between the input shaft
1
and output shaft
3
, the trunnions
6
,
6
may be respectively swung in a given direction about their associated pivot shafts
5
,
5
. And, as shown in
FIG. 6
, the displacement shafts
7
,
7
may be respectively inclined in such a manner that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
can be respectively contacted with the near-to-center portion of the inner surface
2
a
of the input side disk
2
and with the near-to-outer-periphery portion of the inner surface
4
a
of the output side disk
4
. On the other hand, in the case of acceleration, the trunnions
6
,
6
may be respectively swung in the opposite direction to the above given direction. And, as shown in
FIG. 7
, the displacement shafts
7
,
7
may be respectively inclined in such a manner that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
can be respectively contacted with the near-to-outer-periphery portion of the inner surface
2
a
of the input side disk
2
and with the near-to-center portion of the inner surface
4
a
of the output side disk
4
. By the way, in case where the inclination angles of the displacement shafts
7
,
7
are set in the intermediate angles between those shown in
FIGS. 6 and 7
, there can be obtained an intermediate gear change ratio between the input shaft
1
and output shaft
3
.
Further,
FIG. 8
shows a toroidal-type continuously variable transmission disclosed in Japanese Utility Model Unexamined Publication No. Sho.62-199557, which is a further concrete version of the transmission for a vehicle. Specifically, in this toroidal-type continuously variable transmission, the rotation of a crank shaft provided in the engine of the vehicle is transmitted through a clutch
15
to an input shaft
16
to thereby rotate a cam plate
10
which is spline engaged with the intermediate portion of the input shaft
16
. And, due to the operation of a pressing device
9
including the cam plate
10
, an input side disk
2
is pushed and rotated to the left in
FIG. 8
toward an output side disk
4
. The rotation of the input side disk
2
is transmitted to the output side disk
4
through power rollers
8
,
8
.
The output side disk
4
is supported on the periphery of the input shaft
16
by a needle roller bearing
17
. Also, a cylindrical-shaped output shaft
18
, which is formed integral with the output side disk
4
, is supported on the interior of a housing
19
by a ball bearing
20
of an angular type. On the other hand, one end (in
FIG. 8
, the right end) of the input shaft
16
is rotatably supported on the interior of the housing
19
by a roller bearing
21
. At this time, the other end thereof is rotatably supported on the interior of the housing
19
by a ball bearing
22
of an angular type through a sleeve
23
.
Also, a transmission gear
26
, which is an integral body of a drive side advancing gear
24
and a drive side retreating gear
25
, is spline engaged with the outer peripheral surface of the output shaft
18
. When advancing the vehicle, the transmission gear
26
is moved to the right in
FIG. 8
to thereby bring the drive side advancing gear
24
into direct meshing engagement with a driven side advancing gear
28
disposed in the intermediate portion of a
Kobayashi Norihisa
Nogi Takashi
Bucci David A.
McAnulty Timothy
NSK Ltd.
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