Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
2001-04-02
2002-05-14
Bonck, Rodney H. (Department: 3681)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
Reexamination Certificate
active
06387010
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power roller unit and an output disc unit for a toroidal type continuously variable transmission and more particularly, it relates to a power roller unit and an output disc unit which can make an assembling operation easy as for a toroidal type continuously variable transmission used, for example, as a transmission for a motor vehicle or a transmissions for various industrial machines, and can improve performance thereof by improving accuracy.
2. Related Background Art
As a transmission for a motor vehicle, use of a toroidal type continuously variable transmission as shown in
FIGS. 21 and 22
has been investigated. For example, as disclosed in Japanese Utility Model Application Laid-open No. 62-71465 (1987), in the toroidal type continuously variable transmission, an input disc
2
is supported in coaxial with an input shaft
1
and an output disc
4
is secured to an end of an output shaft
3
disposed coaxially with the input shaft
1
. Within a casing containing the toroidal type continuously variable transmission, there are provided trunnions
6
rockable around pivot shafts
5
disposed in twisted relations to the input shaft
1
and the output shaft
3
.
That is to say, the pivot shafts
5
are provided on outer surfaces of these trunnions
6
at both ends thereof in a coaxial relation. Intermediate portions of the trunnions
6
support proximal ends of displacement shafts
7
so that, when the trunnions
6
are rocked around the pivot shafts
5
, inclined angles of the displacement shafts
7
can be adjusted. Power rollers
8
are rotatably supported around the displacement shafts
7
supported by the trunnions
6
. The power rollers
8
are interposed between opposed inner surfaces
2
a,
4
a
of an input disc
2
and of an output disc
4
. Each of the inner surfaces
2
a,
4
a
has a concave surface obtained by rotating an arc around each pivot shaft
5
. Peripheral surfaces
8
a
(formed as spherical convex surfaces) of the power rollers
8
abut against the inner surfaces
2
a,
4
a.
An urging device
9
of loading cam type is disposed between the input shaft
1
and the input disc
2
so that the input disc
2
can be urged elastically toward the output disc
4
by the urging device
9
. The urging device
9
comprises a cam plate
10
rotated together with the input shaft
1
, a plurality (for example, four) of rollers
12
rotatably retained (held) by a retainer (holder)
11
. A drive cam surface (circumferential uneven (convex and concave) surface)
13
is formed one side (left side surface in
FIGS. 21 and 22
) of the cam plate
10
, and a driven cam surface
14
having similar configuration is formed on an outer surface (right side surface in
FIGS. 21 and 22
) of the input disc
2
. The plurality of rollers
12
are supported for rotation around shafts directed radially with respect to a center of the input shaft
1
.
In use of the toroidal type continuously variable transmission having the above-mentioned construction, when the cam plate
10
is rotated as the input shaft
1
is rotated, the drive cam surface
13
urges the plurality of rollers
12
against the driven cam surface
14
formed on the outer surface of the input disc
2
. As a result, the input disc
2
is urged against the power rollers
8
, and, at the same time, the input disc
2
is rotated by the urging force between the drive and driven cam surfaces
13
,
14
and the plurality of rollers
12
. The, rotation of the input disc
2
is transmitted to the output disc
4
through the power rollers
8
, thereby rotating the output shaft
3
secured to the output disc
4
.
When a rotational speed ratio (transmission ratio) between the input shaft
1
and the output shaft
3
is changed, and particularly when speed reduction is effected between the input shaft
1
and the output shaft
3
, the trunnions
6
are rotated in predetermined directions around the pivot shafts
5
. And, the displacement shafts
7
are inclined so that the peripheral surfaces
8
a
of the power rollers
8
abut against a center side portion of the inner surface
2
a
of the input disc
2
and a peripheral side portion of the inner surface
4
a
of the output disc
4
, respectively, as shown in FIG.
21
. On the other hand, when speed increase is effected, the trunnions
6
are rotated in reverse directions around the pivot shafts
5
. And, the displacement shafts
7
are inclined so that the peripheral surfaces
8
a
of the power rollers
8
abut against a peripheral side portion of the inner surface
2
a
of the input disc
2
and a center side portion of the inner surface
4
a
of the output disc
4
, respectively, as shown in FIG.
22
. When the inclination angles of the displacement shafts
7
are selected to intermediate values between FIG.
21
and
FIG. 22
, an intermediate transmission ratio can be obtained between the input shaft
1
and the output shaft
3
.
FIGS. 23 and 24
show an example of a more concrete toroidal type continuously variable transmission disclosed in Japanese Utility Model Laid-open No. 1-173552 (1989). An input disc
2
and an output disc
4
are rotatably supported around a circular tubular input shaft
115
via needle bearings
16
, respectively. A cam plate
10
is spline-connected to a peripheral surface of an end (left end in
FIG. 23
) of the input shaft
15
and is prevented from shifting a way from the input disc
2
by a flange
17
. The cam plate
10
and a plurality of rollers
12
constitute an urging device
9
of loading cam type for rotating the input disc
2
while urging the input disc toward the output disc
4
on the basis of rotation of the input shaft
15
. An output gear
18
is coupled to the output shaft
4
via keys
19
so that the input disc
4
and the output gear
18
can be rotated in a synchronous manner.
Both ends of a pair of trunnions
6
are supported by a pair of support plates
20
for rocking movement and displacement movement in an axial direction (direction perpendicular to the plane of
FIG. 23
; left-and-right direction in FIG.
24
). That is to say, radial needle bearings (first radial bearings)
22
are provided between outer peripheral surfaces of pivot shafts
5
secured to the both ends of the trunnions
6
and inner peripheral surfaces of circular holes
21
formed in both ends of the support plates
20
. Outer peripheral surfaces of outer races
23
of the radial needle bearings
22
are spherical convex surfaces so that these races are inserted within the circular holes
21
for rocking movement and axial displacement movement.
Displacement shafts
7
are supported within circular holes
24
formed in intermediate portions of the trunnions
6
supported between the pair of support plates
20
for rocking movement and axial displacement movement in this way. The displacement shaft
7
have support shaft portions
25
and pivot shaft portions
26
which are parallel with each other and eccentric (offset) from each other. The support shaft portions
25
are rotatably supported within the circular holes
24
via radial needle bearings (second radial bearings)
27
. Power rollers
8
are rotatably supported around the pivot shaft portions
26
via radial needle bearings (third radial bearings)
28
.
Incidentally, the pair of displacement shafts
7
are diametrically opposed with each other with respect to the input shaft
15
. Directions of offset of the pivot shaft portions
26
of the displacement shafts
7
with respect to the support shaft portions
25
are the same (left and right opposite directions in
FIG. 24
) with respect to the rotational direction of the input and output discs
2
,
4
. Further, the offset directions are substantially perpendicular to the direction of the input shaft
15
. Accordingly, the power rollers
8
are supported for a slight displacement movement in the direction of the input shaft
15
. As a result, even if the power rollers
8
tend to displace along the axial direction (left-and-right direction in
FIG. 23
; directio
Fujinami Makoto
Goto Nobuo
Itoh Hiroyuki
Kato Hiroshi
Machida Hisashi
Bonck Rodney H.
Miles & Stockbridge P.C.
NSK Ltd.
Parekh Ankur
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