Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
2001-09-13
2004-04-06
Bucci, David A. (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C476S002000, C476S010000
Reexamination Certificate
active
06716135
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toroidal-type continuously variable transmission which can be used, for example, as a transmission unit for a transmission of a vehicle or as a transmission for various industrial machines.
2. Description of the Related Art
Conventionally, use of such a toroidal-type continuously variable transmission as shown in
FIGS. 5 and 6
as a transmission of a vehicle has been studied and used in some sectors of the vehicle industry. In this toroidal-type continuously variable transmission, for example, as disclosed in JP-62-714650, 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
which is disposed concentrically with the input shaft
1
. In the interior of a casing
5
(see
FIG. 8
which will be discussed later) in which a toroidal-type continuously variable transmission is stored, there are disposed trunnions
7
,
7
respectively swingable about their associated pivot shafts
6
,
6
which are disposed at positions respectively twisted with respect to the input shaft
1
and output shaft
3
.
On each of the trunnions
7
,
7
, there are disposed a pair of units (two units) of the above-mentioned pivot shafts
6
; more specifically, the pair of pivot shafts
6
are disposed on the outer surfaces of the two end portions of each trunnion
7
in such a manner that the two pivot shafts
6
,
6
are concentric with each other. The center axes of these pivot shafts
6
,
6
are present at twisted positions which do not cross with the center axes of the disks
2
,
4
but extend in a direction at right angles or substantially right angles with respect to the direction of the center axes of the disks
2
,
4
. Also, the base half sections of displacement shafts
8
,
8
are supported on the central portions of the trunnions
7
,
7
and thus, by swinging the trunnions
7
,
7
about the pivot shafts
6
,
6
, the inclination angles of the displacement shafts
8
,
8
can be adjusted freely. On the peripheries of the front half sections of the displacement shafts
8
,
8
which are respectively supported on their associated trunnions
7
,
7
, there are rotatably supported power rollers
9
,
9
, respectively. And, the power rollers
9
,
9
are held by and between the respective inner surfaces
2
a,
4
a
of the input side and output side disks
2
,
4
.
The section of each of the mutually opposing inner surfaces
2
a,
4
a
of the input side and output side disks
2
,
4
has an arc-shaped concave surface which can be obtained by rotating an arc with the pivot shaft
6
as the center thereof or by rotating a curved line which is approximate to such arc. And, the peripheral surfaces
9
a,
9
a
(each of which is formed as a spherically convex surface) of the power rollers
9
,
9
are respectively 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 loading cam device
10
, and the loading cam device
10
presses the input side disk
2
elastically toward the output side disk
4
, to thereby drive or rotate the input side disk
2
freely.
When the above-structured toroidal-type continuously variable transmission is in use, as the input shaft
1
is rotated, the loading cam device
10
rotates the input side disk
2
while pressing it against the plurality of power rollers
9
,
9
. And, the rotation of the input side disk
2
is transmitted through the plurality of power rollers
9
,
9
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, in case where deceleration is made between the input shaft
1
and output shaft
3
, the trunnions
7
,
7
are respectively swung about their associated pivot shafts
6
,
6
to thereby incline the displacement shafts
6
,
8
in such a manner that the peripheral surfaces
9
a,
9
a
of the power rollers
9
,
9
, as shown in
FIG. 5
, are 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, in the case of acceleration, the trunnions
7
,
7
are respectively swung about their associated pivot shafts
6
,
6
to thereby incline the displacement shafts
8
,
8
in such a manner that the peripheral surfaces
9
a,
9
a
of the power rollers
9
,
9
, as shown in
FIG. 6
, are 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
. By the way, in case where the inclination angles of the displacement shafts
8
,
8
are set in the intermediate between those shown in
FIGS. 5 and 6
, there can be obtained an intermediate gear change ratio between the input shaft
1
and output shaft
3
.
Further,
FIGS. 7 and 8
respectively show a further specific version of a toroidal-type continuously variable transmission which is disclosed in U.S. Pat. No. 4,955,246. Specifically, in this toroidal-type continuously variable transmission, an input side disk
2
and an output side disk
4
are rotatably supported on the periphery of a cylindrical-shaped input shaft
11
, respectively. Also, between the input side disk
2
and the end portion of the input shaft
11
, there is interposed a loading cam device
10
. On the other hand, to the output side disk
4
, there is connected an output gear
12
in such a manner that the output side disk
4
and output gear
12
can be rotated in synchronization with each other.
In the toroidal-type continuously variable transmission, there are disposed a pair of trunnions
7
,
7
. On the two end portions of each trunnion
7
, there are disposed pivot shafts
6
,
6
which are concentric with each other. The pivot shafts
6
,
6
are respectively supported on a pair of support plates
13
,
13
serving as support members in such a manner that they can be swung and can be shifted in the axial direction thereof (in
FIG. 7
, in the front and back direction; and, in
FIG. 8
, in the right and left direction). And, the base half sections of displacement shafts
8
,
8
are supported on the intermediate portions of the trunnions
7
,
7
. These displacement shafts
8
,
8
are structured such that the base half sections and front half sections thereof are eccentric with respect to each other. Also, the base half sections of the displacement shafts
8
,
8
are rotatably supported on the intermediate portions of the trunnions
7
,
7
, while power rollers
9
,
9
are rotatably supported on the front half sections of the displacement shafts
8
,
8
, respectively.
By the way, the pair of displacement shafts
8
,
8
are disposed at positions just 180° opposite to each other with the input shaft
11
between them. Also, the direction in which the base half sections and front half sections of the displacement shafts
8
,
8
are eccentric with each other is set as the same direction (in
FIG. 8
, the reversed right-and-left direction) with respect to the rotation direction of the input side and output side disks
2
,
4
. Further, this eccentric direction is a direction which extends substantially at right angles to a direction where the input shaft
11
is disposed. Therefore, the power rollers
9
,
9
are supported in such a manner that they can be shifted slightly with respect to the direction where the input shaft
11
is disposed.
Also, between the outer surfaces of the power rollers
9
,
9
and the inner surfaces of the intermediate portions of the trunnions
7
,
7
, there are interposed thrust ball bearings
14
,
14
and thrust needle roller bearings
15
,
15
sequentially in order starting from the outer surfaces of
Bucci David A.
NSK Ltd.
Smith Julie K.
Sughrue & Mion, PLLC
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