Friction gear transmission systems or components – Condition responsive ratio change – Fluid control
Reexamination Certificate
2000-07-11
2002-12-03
Joyce, William C (Department: 3682)
Friction gear transmission systems or components
Condition responsive ratio change
Fluid control
C476S010000, C476S040000
Reexamination Certificate
active
06488607
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toroidal type continuously variable transmission used as a speed changing unit constituting an automatic transmission of a vehicle. Particularly, the present invention aims to achieve excellent transmitting efficiency and durability by synchronizing various power transmitting portions with each other when a quick speed changing operation is effected.
2. Related Background Art
As an automatic transmission of a motor vehicle, usage of a toroidal type continuously variable transmission as schematically shown in
FIGS. 1 and 2
has been investigated. For example, as disclosed in Japanese Utility Model Application Laid-Open No. 62-71465, in the toroidal type continuously variable transmission, an input side disc
2
is supported coaxially with an input shaft
1
, and an output side disc
4
is secured to an end of an output shaft
3
disposed coaxially with the input shaft
1
. Within a casing
5
(refer to
FIG. 4
which will described later) containing the toroidal type continuously variable transmission, trunnions
7
pivoted around pivot shafts
6
arranged positions twisted with respect to the input shaft
1
and the output shaft
3
.
Each trunnion
7
is provided at its outer surface (on both ends thereof) with a pair of coaxial pivot shafts
6
. Central axes of the pivot shafts
6
do not intersect with the central axis of the discs
2
,
4
but are located at twisted positions perpendicular to the central axis of the discs
2
,
4
. Further, each trunnion
7
supports a proximal half portion of a displacement shaft
8
so that an inclined angle of the displacement shaft
8
can be adjusted by rocking the trunnion
7
around the pivot shafts
6
. Around a distal half portion of the displacement shaft
8
supported by each trunnion
7
, a power roller
9
is rotatably supported. The power rollers
9
are disposed between inner surfaces
2
a
,
4
a
of the input and output side discs
2
,
4
.
The opposed inner surfaces
2
a
,
4
a
of the input and output side discs
2
,
4
have concave surfaces of arcuate section obtained by rotating arcs or similar curves around the input and output shafts. Peripheral surfaces
9
a
of the power rollers
9
are spherical convex surfaces that abut against the inner surfaces
2
a
,
4
a
. Further, an urging device
10
such as a loading cam is disposed between the input shaft
1
and the input side disc
2
, so that the input side disc
2
can be rotated while elastically urging it toward the output side disc
4
by the urging device
10
.
When the toroidal type continuously variable transmission having the above-mentioned construction is used, as the input shaft
1
is rotated, the urging device
10
rotates the input side disc
2
while urging it against the plural power rollers
9
. Rotation of the input side disc
2
is transmitted to the output side disc
4
via the plural power rollers
9
, thereby rotating the output shaft
3
secured to the output side disc
4
.
When a rotational speed ratio (transmission ratio) between the input shaft
1
and the output shaft
3
is changed, and particularly when the speed reduction is effected between the input shaft
1
and the output shaft
3
, the trunnions
7
are rocked around the pivot shafts
6
to incline the displacement shafts
8
so that, as shown in
FIG. 1
, the peripheral surfaces
9
a
of the power rollers
9
abut against portions of the inner surface
2
a
of the input side disc
2
near the center thereof and portions of the inner surface
4
a
of the output side disc
4
near the outer periphery thereof.
Conversely, when the speed increase is effected, the trunnions
7
are rocked to incline the displacement shafts
8
so that, as shown in
FIG. 2
, the peripheral surfaces
9
a
of the power rollers
9
abut against portions of the inner surface
2
a
of the input side disc
2
near the outer periphery thereof and portions of the inner surface
4
a
of the output side disc
4
near the center thereof. When the inclined angles of the displacement shafts
8
are selected to an intermediate values between FIG.
1
and
FIG. 2
, an intermediate speed ratio can be obtained.
FIGS. 3 and 4
show in more detail a toroidal type continuously variable transmission as disclosed in Japanese Utility Model Application No. 63-69293 (Japanese Utility Model Application Laid-Open No. 1-173552). An input side disc
2
and an output side disc
4
are rotatably supported around a cylindrical tubular input shaft
11
. Further, an urging device
10
is disposed between an end of the input shaft
11
and the input side disc
2
. On the other hand, an output gear
12
is connected to the output side disc
4
so that they are rotated in sychronism with each other.
Coaxial pivot shafts
6
provided on both ends of a pair of trunnions
7
are supported by a pair of support plates (yokes)
13
for rocking movement and axial movement (movement perpendicular to the plane of
FIG. 3
; movement in an up-and-down direction in FIG.
4
). The trunnions
7
support proximal half portions of displacement shafts
8
at their intermediate portions. In each displacement shaft
8
, the proximal half portion and a distal half portion are eccentric from each other. The proximal half portions are rotatably supported by the intermediate portions of the trunnions
7
, and power rollers
9
are rotatably supported by the distal half portions. Further, a synchro-cable
27
is mounted between the ends of the trunnions
7
with cross belting so that inclined angles of the trunnions can be synchronized mechanically.
The pair of displacement shafts
8
are diametrically opposed with respect to the input shaft
11
. Further, the eccentric directions of the proximal half portions and the distal half portions of the displacement shafts
8
are the same (opposite directions vertically in
FIG. 4
) with respect to the rotational directions of the input and output side discs
2
,
4
. Further, the eccentric directions are substantially perpendicular to the installation direction of the input shaft
11
. Accordingly, the power rollers
9
are supported for slight movement in the installation direction of the input shaft
11
.
Further, between the outer peripheral surfaces of the power rollers
9
and intermediate portions of the inner surfaces of the trunnions
7
, there are disposed, in order from the power rollers
9
, thrust ball bearings
14
and thrust needle bearings
15
. The thrust ball bearings
14
serve to support thrust loads acting on the power rollers
9
and to permit rotations of the power rollers
9
. Further, the thrust needle bearings
15
serve to support thrust loads applied from the power rollers
9
to outer races
16
of the thrust ball beatings
14
and to permit the distal half portions of the displacement shafts
8
and the outer races
16
to rock around the proximal half portions of the displacement shafts
8
. Further, the trunnions
7
can be shifted along axial directions of the pivot shafts
6
by means of hydraulic actuators (for example, hydraulic cylinders)
17
.
In case of the toroidal type continuously variable transmission having the above-mentioned construction, the rotation of the input shaft
11
is transmitted to the input side disc
2
via the urging device
10
. The rotation of the input side disc
2
is transmitted to the output side disc
4
via the pair of power rollers
9
, and the rotation of the output side disc
4
is picked up by the output gear
12
.
When a rotational speed ratio between the input shaft
11
and the output gear
12
is changed, the pair of trunnions
7
are displaced by the actuators
17
in opposite directions (for example, the right power roller
9
in
FIG. 4
is displaced downwardly and the left power roller
9
in
FIG. 4
is displaced upwardly). As a result, directions of tangential forces acting between the peripheral surfaces
9
a
of the power rollers
9
and the inner surfaces
2
a
,
4
a
of the input and output side discs
2
,
4
are changed. As such directions are cha
Imanishi Takashi
Machida Hisashi
Tanaka Hirohisa
Joyce William C
Miles & Stockbridge P.C.
NSK Ltd.
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