Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
2000-07-14
2001-12-04
Bucci, David A. (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C476S040000, C476S042000, C411S283000, C411S462000, C411S544000, C411S937200
Reexamination Certificate
active
06325740
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 as a transmission for a car or as a transmission for various kinds of industrial machines.
2. Description of the Related Art
Conventionally, it has been studied that such a toroidal-type continuously variable transmission as shown schematically in
FIGS. 7 and 8
is used as a transmission for a car. In this toroidal-type continuously variable transmission, for example, as disclosed in JP-A-62-71465U, an input side disk
2
is supported concentrically with an input shaft
1
, while 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 portion of a casing in which the toroidal-type continuously variable transmission is stored, there are disposed trunnions
6
,
6
which are capable of swinging about their associated paired pivot shafts
5
,
5
disposed at a torsional position with respect to the input and output shafts
1
and
3
: specifically, the torsional position is a position which does not intersect the center axes of the input side and output side disks
2
,
4
and are perpendicular to the directions of the center axes of the input side and output side disks
2
,
4
.
That is, in each of the trunnions
6
,
6
which is disposed in the portion that is shifted from the center axes of the two disks
2
,
4
, on the outer surfaces of their respective two end portions, there are disposed the paired pivot shafts
5
,
5
in such a manner that they extend at right angles to the directions of the center axes of the two disks
2
,
4
and are concentric with each other. Also, on the middle portions of the trunnions
6
,
6
, there are supported the base end portions of displacement shafts
7
,
7
; and, the inclination angles of the displacement shafts
7
,
7
can be adjusted by swinging the trunnions
6
,
6
about their respective paired pivot shafts
5
,
5
. On the peripheries of the displacement shafts
7
,
7
thus supported on the trunnions
6
,
6
, there are rotatably supported power rollers
8
,
8
. And, the power rollers
8
,
8
are held by and between the mutually opposing inner surfaces
2
a
,
4
a
of the input side and output side disks
2
,
4
. Each of the inner surface
2
a
,
4
a
has a cross section formed as a concave surface which can be obtained when an arc having the pivot shaft
5
as the center thereof is rotated. 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.
Between the input shaft
1
and input side disk
2
, there is disposed a loading cam device
9
; that is, the loading cam device
9
is capable of driving the input side disk
2
rotationally while pressing the input side disk
2
elastically toward the output side disk
4
. The loading cam device
9
is composed of a loading cam
10
rotatable together with the input shaft
1
, and a plurality of (for example, four) rollers
12
,
12
which are rollably held by a retainer
11
. On one side surface (in
FIGS. 7 and 8
, the right surface) of the loading cam
10
, there is formed a cam surface
13
which is a curved surface extending in the circumferential direction of the loading cam
10
; and, on the outer surface (in
FIGS. 7 and 8
, the left surface) of the input side disk
2
as well, there is formed a cam surface
14
having a similar shape to the cam surface
13
. And, the plurality of rollers
12
,
12
are supported in such a manner that they can be rotated about their respective axes extending in the 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 loading cam
10
is rotated as the input shaft
1
is rotated, 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, due to the mutual pressing actions between the two cam surfaces
13
,
14
and the plurality of rollers
12
,
12
, 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
, so that the output shaft
3
fixed to the output side disk
4
can be rotated.
Now, description will be given below of a case where a rotation speed ratio (transmission ratio) between the input shaft
1
and output shaft
3
is changed. At first, when reducing the rotation speed ratio between the input shaft
1
and output shaft
3
, the trunnions
6
,
6
may be respectively swung in a given direction about their respective paired pivot shafts
5
,
5
. And, the displacement shafts
7
,
7
maybe inclined respectively in such a manner that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
, as shown in
FIG. 7
, can be respectively contacted with the near-center portion of the inner surface
2
a
of the input side disk
2
and the near-outer-periphery portion of the inner surface
4
a
of the output side disk
4
. On the other hand, when increasing the rotation speed ratio between the input shaft
1
and output shaft
3
, the trunnions
6
,
6
may be respectively swung in the opposite direction to the given direction about their respective paired pivot shafts
5
,
5
. And, the displacement shafts
7
,
7
may be inclined respectively in such a manner that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
, as shown in
FIG. 8
, can be respectively contacted with the near-outer-periphery portion of the inner surface
2
a
of the input side disk
2
and the near-center portion of the inner surface
4
a
of the output side disk
4
. Also, in case where the inclination angles of the displacement shafts
7
,
7
are set in the intermediate angles between the angles shown in
FIGS. 7 and 8
, there can be obtained an intermediate transmission ratio between the input and output shafts
1
,
3
.
Also,
FIGS. 9 and 10
show an example of a more specifically structured toroidal-type continuously variable transmission which is disclosed in JP-A-1-173552U. An input side disk
2
serving as a first disk and an output side disk
4
serving as a second disk are respectively supported on the periphery of a cylinder-like input shaft
15
serving as a rotary shaft in such a manner that they can be rotated through needle roller bearings
16
,
16
. That is, in the respective central portions of the input side and output side disks
2
,
4
, there are formed through holes
17
,
17
each having a circular cross section in such a manner that they respectively extend through the inside and outside surfaces of the input side and output side disks
2
,
4
in the axial direction (in
FIG. 9
, in the right and left direction) of the disks
2
,
4
. The needle roller bearings
16
,
16
are respectively interposed between the inner peripheral surfaces of the through holes
17
,
17
and the outer peripheral surface of the middle portion of the input shaft
15
. In the inner peripheral surfaces of the near-inside-surface end portions of the through holes
17
,
17
, there are formed securing grooves
18
,
18
; and, retaining rings
19
,
19
are secured to the securing grooves
18
,
18
respectively to thereby prevent the needle roller bearings
16
,
16
from slipping out from their respective through holes
17
,
17
toward the inside surfaces
2
a
,
4
a
of the input side and output side disks
2
,
4
. Also, the loading cam
10
is spline engaged with the outer peripheral surface of the end portion (in
FIG. 9
, the left end portion) of the input shaft
15
; and, a flange portion
20
of the loading cam
10
prevents the thus engaged loading cam
10
from moving in a direction where it parts away from the
Goto Nobuo
Ishikawa Kouji
Kobayashi Norihisa
Bucci David A.
Joyce William C
NSK Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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