Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
2000-04-05
2002-07-09
Herrmann, Allan D. (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C476S046000, C384S558000, C384S564000
Reexamination Certificate
active
06416439
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved toroidal-type continuously variable transmission to be used as a transmission for a car and, in particular, to such transmission having a structure which is easy to assemble and is able to sufficiently secure the load capacities of the support portions of trunnions employed therein.
2. Description of the Related Art
It has been studied to use such toroidal-type continuously variable transmission as shown in
FIGS. 13 and 14
as a transmission for a car. This toroidal-type continuously variable transmission is a transmission which is called a half-toroidal-type continuously variable transmission. In the half-toroidal-type continuously variable transmission, for example, as disclosed in Japanese Utility Model Unexamined Publication No. 62-71465 of Showa, 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
disposed concentrically with the input shaft
1
. In the inside of a casing with the toroidal-type continuously variable transmission stored therein and at the intermediate positions of the input side and output side disks
2
and
4
in the axial direction thereof, there are disposed two trunnions
6
,
6
. The two trunnions
6
,
6
can be swung about their respective pivot shafts
5
and
5
disposed at torsional positions which respectively lie in a direction at right angles (in
FIGS. 13 and 14
, the front and back direction) to the direction (in
FIGS. 13 and 14
, the right and left direction) of the input and output shafts
1
and
3
but do not intersect the axes of the input and output shafts
1
and
3
.
That is, in the two trunnions
6
,
6
, the pivot shafts
5
,
5
are disposed on the outer surfaces of their respective two end portions in such a manner that they are concentric with each other. Also, the respective base end portions of displacement shafts
7
,
7
are supported in the intermediate portions of the two trunnions
6
,
6
and, by swinging the two trunnions
6
,
6
about their respective pivot shafts
5
,
5
, the inclination angles of the two displacement shafts
7
,
7
can be freely adjusted. On the peripheries of the two displacement shafts
7
,
7
supported on their respective trunnions
6
,
6
, there are supported power rollers
8
,
8
in such a manner that they can be freely rotated. And, these power rollers
8
,
8
are respectively held by and between the mutually opposing inner surfaces
2
a
and
4
a
of the input side and output side disks
2
and
4
. The sections of the inner surfaces
2
a
and
4
a
are respectively formed in a concave-shaped surface which can be obtained by rotating an arc having the pivot shaft
5
as its center. And, the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
, which are respectively formed in a spherically convex-shaped surface, are in contact with the inner surfaces
2
a
and
4
a.
Between the input shaft
1
and input side disk
2
, there is disposed a pressure device
9
of a loading cam type, whereby the input side disk
2
can be elastically pressed toward the output disk
4
by the pressure device
9
. The pressure device
9
is composed of a cam plate
10
rotatable together with the input shaft
1
and a plurality of (for example, 4) rollers
12
,
12
which are rollably held by a retainer
11
. On one side surface (in
FIGS. 13 and 14
, the right side surface) of the cam plate
10
, there is formed a cam surface
13
which extends unevenly in the circumferential direction of the cam plate
10
; and, on the outer side surface (in
FIGS. 13 and 14
, the left side surface) of the input side disk
2
, there is also formed a cam surface
14
having a similar shape. And, the plurality of rollers
12
,
12
are rotatably supported 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 cam plate
10
is rotated with the rotation of the input shaft
1
, 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 pressure 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.
When changing a rotation speed ratio (change gear ratio) between the input shaft
1
and output shaft
3
, at first, in case where deceleration is carried out between the input shaft
1
and output shaft
3
, the trunnions
6
and
6
are swung about their respective pivot shafts
5
and
5
in a given direction. The displacement shafts
7
and
7
are respectively inclined in such a manner that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
are, as shown in
FIG. 13
, respectively contacted with the near-to-center portion of the inner surface
2
a
of the input side disk
2
and with the near-to-outer-periphery portion of the inner surface
4
a
of the outside disk
4
(Here, “near-to-A portion” means a portion which is located near to A). Contrary to the above, in case where acceleration is carried out, the trunnions
6
,
6
are swung about their respective pivot shaft
5
,
5
in the opposite direction to the above-mentioned given direction. And, the displacement shafts
7
,
7
are respectively inclined in such a manner that the peripheral surfaces
8
a
,
8
a
of the power rollers
8
,
8
are, as shown in
FIG. 14
, respectively contacted with the near-to-outer-periphery portion of the inner surface
2
a
of the input side disk
2
and with the near-to-center portion of the inner surface
4
a
of the outside disk
4
. Also, in case where the inclination angles of the displacement shafts
7
,
7
are respectively set in the middle of the angles shown
FIGS. 13 and 14
, a middle change gear ratio can be obtained.
Now,
FIGS. 15 and 16
show a more specific version of a toroidal-type continuously variable transmission which is disclosed in Japanese Utility Model Unexamined Publication No. 1-173552 of Heisei. An input side disk
2
and an output side disk
4
are rotatably supported on the periphery of a tubular input shaft
15
respectively through needle roller bearings
16
,
16
. Also, a cam plate
10
is spline engaged with the outer peripheral surface of the end portion (in
FIG. 15
, left end portion) of the input shaft
15
, while a flange portion
17
prevents the cam plate
10
from moving in a direction where it goes away from the input side disk
2
. And, this cam plate
10
cooperates together with a plurality of rollers
12
,
12
, so as to form a pressure device
9
which, based on the rotation of the input shaft
15
, can rotate the input side disk
2
while pressing the input side disk
2
toward the output side disk
4
. To the output side disk
4
, there is coupled an output gear
18
by keys
19
,
19
, so that the output side disk
4
and output gear
18
can be rotated synchronously.
The pivot shafts
5
,
5
, which are disposed in the respective two end portions of the pair of trunnions
6
and
6
, are respectively supported on a pair of support plates
20
and
20
in such a manner that they can be freely swung and shifted in their respective axial direction (that is, in
FIG. 15
, in the front and back direction; and, in
FIG. 16
, in the right and left direction). In other words, the pair of support plates
20
and
20
are disposed almost in parallel to each other within a housing
21
storing the main body portion of a toroidal-type continuously variable transmission in such a manner that they hold the in
Goto Nobuo
Higuchi Seiji
Itoh Hiroyuki
Kobayashi Norihisa
Tanaka Masami
Herrmann Allan D.
NSK Ltd.
Sughrue & Mion, PLLC
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