Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
1998-10-29
2001-01-16
Footland, Lenard A. (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
Reexamination Certificate
active
06174258
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toroidal-type continuously variable transmission (CVT) and, more particularly, to a continuously variable transmission in which the material of a trunnion is strengthened and the surfaces of certain portions are hardened by a simplified method.
2. Related Background Art
As an automotive transmission, a toroidal-type continuously variable transmission shown in FIG.
1
and disclosed in Japanese Utility Model Application Laid-Open No. 62-71465 has been used. In the transmission as shown in
FIG. 1
, an input-side disk
12
is supported coaxially with an input shaft
11
, and an output-side disk
14
is fixed to the end of an output shaft
13
disposed coaxially with the input shaft
11
.
Trunnions
16
are provided with an axis (shaft) portion
15
, which lies at a torsional position with respect to the input shaft
11
and the output shaft
13
, at the outer side at both ends, and the base of a displacement shaft
17
is supported at the center of the trunnion
16
. Thereby, the trunnion
16
is swayed or rocked around the axis portion
15
so that the tilt angle of the displacement shaft
17
can be adjusted freely. A power roller
18
, which is held between the input-side disk
12
and the output-side disk
14
, is rotatably supported by the displacement shaft
17
. Opposed inside surfaces
12
a
and
14
a
of the input-side disk
12
and the output-side disk
14
each has a cross section consisting of a concave surface obtained by rotating an arc around the axis of the disks
12
,
14
, and the peripheral surface
18
a
of power roller
18
is formed into a spherical convex surface which abuts on the inside surfaces
12
a
and
14
a.
Behind the input-side disk
12
, there is provided a loading cam type pressing device
19
, which elastically presses the input-side disk
12
toward the output-side disk
14
. The pressing device
19
is made up of a cam plate
20
rotating together with the input shaft
11
and a plurality of rollers
22
retained by a retainer
21
. On one side surface of the cam plate
20
is formed a cam face
23
in the circumferential direction, and a similar cam face
24
is also formed on the outside surface of the input-side disk
12
. The plurality of rollers
22
are arranged between the cam faces
23
and
24
in the radial direction with respect to the center of the input shaft
11
.
When the cam plate
20
is rotated as the input shaft
11
rotates, the plural rollers
22
are pressed on the cam face
24
of the input-side disk
12
by the cam face
23
. As a result, the input-side disk
12
is pressed on the power roller
18
and rotated, and the rotation of the input-side disk
12
is transmitted to the output-side disk
14
via the power roller
18
, so that the output shaft
13
is rotated.
When deceleration is performed between the input shaft
11
and the output shaft
13
, the trunnion
16
is swayed in one direction around the axis portion
15
, and the displacement shaft
17
is tilted so that the peripheral surface
18
a
of the power roller
18
abuts on the center-side portion of the inside surface
12
a
of the input-side disk
12
and the outer periphery-side portion of the inside surface
14
a
of the output-side disk
14
. When acceleration is performed, the displacement shaft
17
of the trunnion
16
is swayed in the other direction, by which the peripheral surface
18
a
of the power roller
18
is allowed to abut on the outer periphery-side portion of the inside surface
12
a
of the input-side disk
12
and the center-side portion of the inside surface
14
a
of the output-side disk
14
.
A more detailed description will now be given with reference to
FIGS. 2 and 3
. As as shown in
FIGS. 2 and 3
, an input-side disk
102
and an output-side disk
104
are rotatably supported around a tubular input shaft
115
, each via a needle bearing
116
. Also, a cam plate
110
is spline-engaged with the outer peripheral surface of the end of the input shaft
115
, and the movement thereof in the direction apart from the input-side disk
102
is inhibited by a collar
117
. A loading cam type pressing device
109
, which is made up of the cam plate
110
and rollers
112
, rotates the input-side disk
102
based on the rotation of the input shaft
115
while pressing it toward the output-side disk
104
. An output gear
118
is connected to the output-side disk
104
via a key
119
, so that both the elements are rotated synchronously.
A pair of trunnions
106
are supported by a pair of support plates
120
at a pivot portion
105
at both ends so as to be freely swayed around the pivot portion and displaced in the axial direction, and support a displacement shaft
107
at a circular hole
123
portion formed at an intermediate portion. Each of the displacement shafts
107
has an eccentric support shaft portion
121
and a pivotal shaft portion
122
, and both the displacement shafts are in parallel to each other. The support shaft portion
121
is rotatably supported on the inside of the circular hole
123
via a needle bearing
124
, and rotatably supports a power roller
108
at the pivotal shaft portion
122
via a needle bearing
125
.
The paired displacement shafts
107
are provided at 180 degrees opposite positions opposed to each other. Also, the direction in which the pivotal shaft portion
122
is eccentric with respect to the support shaft portion
121
is the same as the direction in which the input-side disk
102
and the output-side disk
104
rotate, and the eccentric direction is substantially perpendicular to the installation direction of the output shaft
115
. Therefore, the power roller
108
is supported in the installation direction of the input shaft
115
so as to be slightly displaced freely. As a result, even if the power roller
108
tends to be displaced in the axial direction of the input shaft
115
due to the dimensional accuracy, elastic deformation, etc. of component, this displacement can be absorbed without applying an excessive force to the component.
Also, between the outside surface of the power roller
108
and the intermediate portion inside surface of the trunnion
106
, there are provided a thrust ball bearing
126
and a thrust needle bearing
127
in that order from the power roller
108
side. The thrust ball bearing
126
, which allows the rotation of the power roller while carrying the load in the thrust direction applied to the power roller
108
, is made up of a plurality of balls
129
, an annular retainer
128
for rotatably retaining the balls, and an annular outer ring
130
.
The thrust needle bearing
127
is made up of an annular race
131
shown in detail in
FIGS. 4 and 5
, a retainer
132
, and needles
133
, and the race
131
and the retainer
132
are combined so as to be slightly displaced freely in the rotational direction. The thrust needle bearing
127
is held between the inside surface of the trunnion
106
and the outside surface of the outer ring
130
in such a state that the race
131
abuts on the inside surface of the trunnion
106
. Further, a driving rod
136
is connected to one end of the trunnion
106
, and a driving piston
137
provided on the intermediate portion outer peripheral surface of the driving rod
136
is fitted in a driving cylinder
138
in an oil tight manner.
At the time of operation of the above toroidal-type CVT, the rotation of the input shaft
115
is transmitted to the input-side disk
102
via pressing device
109
, transmitted to the output-side disk
104
via the paired power rollers
108
, and taken out from an output gear
118
. When the rotational speed ratio between the input shaft
115
and the output gear
118
is changed, the paired driving pistons
137
are displaced in directions reverse to each other, by which the paired trunnions
106
are displaced in reverse directions. As a result, the direction of a tangential force acting on the contact portion between the peripheral surface
108
a
of the power roller
108
and the inside surf
Goto Nobuo
Imanishi Takashi
Kato Hiroshi
Mitamura Nobuaki
Footland Lenard A.
Kim Chong H.
NSK Ltd.
Vorys Sater Seymour and Pease LLP
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