Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
1999-09-23
2002-04-23
Bucci, David A. (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C476S046000, C403S354000
Reexamination Certificate
active
06375595
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
A toroidal type continuously variable transmission according to the present invention can be used, for example, as a speed change unit of a transmission of a motor vehicle or transmissions of various industrial machines.
2. Related Background Art
A toroidal type continuously variable transmission schematically shown in
FIGS. 7 and 8
has been investigated for use as a transmission of a motor vehicle. For example, as disclosed in Japanese Utility Model Laid-Open Application No. 62-71465, in such a toroidal type continuously variable transmission, an, input side disk
2
is supported in coaxial relationship with an input shaft
1
and an output side disk
4
is secured to an end of an output shaft
3
disposed in coaxial relationship with the input shaft
1
. Within a casing containing the torodial type continuously variable transmission, there are provided trunnions
6
rockable around pivot shafts
5
transverse to the input shaft
1
and the output shaft
3
.
Each trunnion
6
is provided at opposite end surfaces with the pivot shafts
5
in coaxial relationship with each other. Further, central portions of the trunnions
6
support proximal ends of displacement shafts
7
so that inclination angles of the displacement shafts
7
can be adjusted by rocking or swinging the trunnions
6
around the pivot shafts
5
. 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
and
4
a
of the input side disk
2
and the output side disk
4
. The inner surfaces
2
a
,
4
a
have concave surfaces obtained by rotating arcs having centers on the pivot shafts
5
. Peripheral surfaces
8
a
of the power rollers
8
having spherical convex shapes abut against the inner surfaces
2
a
,
4
a.
A pressing device
9
of loading cam type is disposed between the input shaft
1
and the input side disk
2
so that the input side disk
2
can be urged elastically toward the output side disk
4
by the pressing device
10
. The pressing device
9
comprises a loading cam (cam plate)
10
rotated together with the input shaft
1
, and a plurality (for example, four) of rollers
12
rotatably held by a holder
11
. One side surface (right side surface in
FIGS. 7 and 8
) of the loading cam
10
is constituted as a cam surface
13
having unevenness or undulation extending along a circumferential direction, and an outer surface (left side surface in
FIGS. 7 and 8
) of the input side disk
2
has a similar cam surface
14
. The plurality of rollers
12
are rotatably supported for rotation around axes extending radially with respect to the center line of the input shaft
1
.
In use of the toroidal type continuously variable transmission having the above-mentioned construction, when the loading cam
10
is rotated as the input shaft
1
is rotated, the plurality of rollers
12
are urged against the cam surface
14
formed on the outer surface of the input side disk
2
by the cam surface
13
. As a result, the input side disk
2
is urged against the plurality of power rollers
8
, and, at the same time, due to the frictional engagement between the cam surfaces
13
,
14
and the plurality of rollers
12
, the input side disk
2
is rotated. Rotation of the input side disk
2
is transmitted to the output side disk
4
through the plurality of power rollers
8
, thereby rotating the output shaft
3
secured to the output side disk
4
.
In a case where a rotational speed ratio (speed change ratio) between the input shaft
1
and the output shaft
3
is changed, when deceleration is effected between the input shaft
1
and the output shaft
3
, the trunnions
6
are rocked or swung around the pivot shafts
5
in predetermined directions, thereby inclining the displacement shafts
7
so that the peripheral surfaces
8
a
of the power rollers
8
abut against a portion of the inner surface
2
a
of the input side disk
2
near the center and a portion of the inner surface
4
a
of the output side disk
4
near its outer periphery, respectively, as shown in FIG.
7
. On the other hand, when acceleration is effected, the trunnions
6
are rocked around the pivot shafts
5
in opposite directions, thereby inclining the displacement shafts
7
so that the peripheral surfaces
8
a
of the power rollers
8
abut against a portion of the inner surface
2
a
of the input side disk
2
near its outer periphery and a portion of the inner surface
4
a
of the output side disk
4
near the center, respectively, as shown in FIG.
8
. If the inclination angles of the displacement shafts
7
are selected to an intermediate value between FIG.
7
and
FIG. 8
, an intermediate speed change ratio can be obtained.
FIGS. 9 and 10
show an example of a toroidal type continuously variable transmission, described in Japanese Utility Model Application Laid-Open No. 1-173552. An input side disk
2
and an output side disk
4
are rotatably supported around a cylindrical input shaft
15
via needle bearings
16
, respectively. Through holes
17
having circular cross-section are formed in central portions of the input side disk
2
and the output side disk
4
so that they pass through inner and outer surfaces of the disks
2
,
4
axially (in a left-and-right direction in FIG.
9
). The needle bearings
16
are disposed between inner peripheral surfaces of the through holes
17
and an outer peripheral surfaces of an intermediate portion of the input shaft
15
. Further, locking grooves
18
formed in inner peripheral surfaces of the through holes
17
near inner surfaces receive stop rings
19
to prevent the needle bearings
16
from dislodging from the through holes
17
toward the inner surfaces
2
a
,
4
a
of the disks
2
,
4
. A loading cam
10
is spline-connected to an end (left end in
FIG. 9
) of the input shaft
15
so that the loading cam is prevented from shifting away from the input side disk
2
by a flange
20
. The loading cam
10
and rollers
12
constitute a pressing device
9
for rotating the input side disk
2
while urging the input side disk toward the output side disk
4
in response to rotation of the input shaft
15
. An output gear
21
is coupled to the output side disk
4
via keys
22
so that the output side disk
4
and the output gear
21
are rotated in a synchronous manner.
The ends of a pair of trunnions
6
are supported by a pair of support plates
23
for rocking movement and axial displacement movement (in a front-and-rear direction in FIG.
9
and left-and-right direction in FIG.
10
). Circular holes
24
formed in intermediate portions of the trunnions
6
support displacement shafts
7
. The displacement shafts
7
have support shaft portions
25
and pivot shaft portions
26
which are parallel to each other and are eccentric from each other. The support shaft portions
25
are rotatably supported within the circular holes
24
via radial needle bearings
27
. Further, power rollers
8
are rotatably supported around the pivot shaft portions
26
via other radial needle bearings
28
.
The pair of displacement shafts
7
are disposed at positions diametrically opposed with respect to the input shaft
15
. Further, directions along which the pivot shaft portions
26
of the displacement shafts
7
are eccentric with respect to the support shaft portions
25
are the-same with respect to the rotational directions of the input side and output side disk
2
,
4
(opposite directions in FIG.
10
). Further, the eccentric directions are substantially perpendicular to the extending direction of the input shaft
15
. Accordingly, the power rollers
8
are supported for slight displacement along the extending direction of the input shaft
15
. As a result, due to elastic deformation of structural members caused by great load acting on the members in the rotational force transmitting condition, even when the power rollers
8
have tendency for displacing toward the axial direction (left-and-right direction in FIG
Imanishi Takashi
Ishikawa Kouji
Machida Hisashi
Bucci David A.
Joyce William C
Miles & Stockbridge P.C.
NSK Ltd.
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