Torodial continuous variable transmission

Details Torodial continuous variable transmission Torodial continuous variable transmission

2000-02-03

2001-06-26

Wright, Dirk (Department: 3681)

Planetary gear transmission systems or components

Nonplanetary variable speed or direction transmission...

Nonplanetary transmission is friction gearing

Reexamination Certificate

active

06251039

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toroidal continuous variable transmission adapted for the vehicle such automobiles.
2. Description of the Prior Art
In most toroidal continuous variable transmissions conventionally used incorporated in the transmission systems in automotive vehicles, the input and output shafts are arranged in a single row along the common centerline. To cope with many restrictions on the layout of the transmission systems, a countershaft having a gear meshed with an output gear connected to an output disk is arranged parallel to an input shaft astride the toroidal transmission mechanism while a spur gear mechanism is arranged-between the countershaft and the output shaft. For getting the rotation of the output disk to the output shaft, thus, either engaging or disengaging a clutch incorporated in the automotive power train brings the output shaft any one of the forward, reverse and neutral. Nevertheless, this prior construction raises major problems of rendering the continuous variable transmission too bulky in its diameter to mount efficiently the transmission to the automotive vehicle.
Among continuous variable transmissions having toroidal continuous variable transmission mechanisms is known a continuous variable transmission, as shown in
FIG. 3
, in which the input and output shafts are arranged in a single row on the common centerline and the rotation of the input shaft may be transmitted to the output shaft with forward speeds, neutral and reverse by speed-changing operation of the toroidal transmission mechanism without no provision of the countershaft so that the continuous variable transmission is reduced in the diametric dimension. Refer to, for example, the disclosure in U.S. Pat. No. 5,607,372.
The continuous variable transmission shown in
FIG. 3
is a continuous variable transmission including therein a toroidal continuous variable transmission mechanism of double cavity type. The toroidal continuous variable transmission mechanism is comprised of a first toroidal transmission unit
8
and a second toroidal transmission unit
9
, which are arranged on an input shaft
1
in opposition to each other. The first toroidal transmission unit
8
includes a first input disk
2
, a first output disk
3
arranged confronting the first input disk
2
, and pivoting power rollers
6
to transmit torque from the first input disk
2
to the first output disk
3
, while the second toroidal transmission
9
has a second input disk
4
, a second output disk
5
arranged confronting the second input disk
4
, and pivoting power rollers
7
to transmit torque from the second input disk
4
to the second output disk
5
. The power rollers
6
,
7
are each for rotation on its own rotating axis
11
and also supported by a trunnion, not shown, for pivoting motion about its associated pivotal axis
12
that is normal to the rotating axis
11
and normal to the plane surface of this paper. This makes it possible to pivot the power rollers
6
,
7
in cooperation with each other whereby the speed ratio may be varied infinitely in accordance with pivoting angles of the power rollers
6
,
7
about the pivotal axes
12
.
While the torque transmission between any paired confronting input and output disks
2
,
4
and
3
,
5
through the power rollers
6
,
7
depends on a shearing force or traction (viscous-frictional force) of hydraulic fluid, the desired tractive effort should require much contact force acting along the axis of the transmission at areas where the power rollers
6
,
7
come in rolling-contact with the input and output disks
2
,
4
and
6
,
7
. To cope with this, the prior toroidal transmission mechanism is commonly provided with a loading cam
10
, or means for adjusting a contact pressure of the power rollers
6
,
7
against the disks, depending on the magnitude of the torque that is applied to the input disks
2
,
4
from the input shaft
1
. In the prior transmission illustrated, a pair of output disks
3
,
5
are made integrally with one another. Reference letters A and B in the accompanying drawing denotes rotational directions of the input and output shafts, respectively. The input shaft
1
extends to the output end, passing through the input and output disks
2
,
4
and
3
,
5
of the toroidal transmission mechanisms
8
,
9
. A hollow drive shaft
15
integral with the output disks
3
,
5
fits over the input shaft
1
for free rotation and also supports thereon the second input disk
4
for rotation.
The torque applied to the input shaft
1
from the engine is transmitted to the first input disk
2
through the loading cam
10
and, at the same time, transmitted to the second input disk
4
past the input shaft
1
. Rotation of the first input disk
2
by the transmitted torque causes the first power rollers
6
rotate so as to turn the first output disk
3
. On the other hand, the torque transmitted to the second input disk
4
drives the second output disk
5
through the second power rollers
7
. It will be understood that the first and second output disks
3
,
5
are made in an integral structure to rotate together in unison. When the power rollers
6
,
7
are pivoted about their pivotal axes for a desired angle in synchronized relation with one another in the event during which the torque is transmitted, the rolling-contact locations of the power rollers
6
,
7
with the input and output disks
2
,
4
and
3
,
5
moves infinitely, thereby resulting in making the transmission ratio vary in a continuous manner.
Arranged downstream of the second toroidal transmission unit
9
is a drive mechanism
46
that is in coaxial relation with both of the input shaft
1
and hollow drive shaft
15
and establishes a power train between the input shaft
1
and the hollow shaft
15
. The drive mechanism
46
is comprised of a first sun gear
47
integral with the input shaft
1
, a carrier
48
mounted on the input shaft
1
and also connected integrally with the second input disk
4
, a torque tube
52
supported for rotation on an extension
14
of the input shaft
1
, a second sun gear
53
provided on the torque tube
52
at the upstream end thereof, and a pinion
49
commonly referred as step-gear. The pinion
49
is supported for rotation at a middle journal thereof and has a gear
50
meshed with the first sun gear
47
and another gear
51
meshed with the second sun gear
53
, the gears
50
and
53
being arranged on axially opposite ends of the middle journal, one to each end. With the construction as described just above, as the first sun gear
47
is opposite in rotating direction to the carrier
48
, the pinion
49
revolves around the first sun gear
47
, spinning on its own axis, to thereby rotate the torque tube
52
in the same rotating direction as the hollow drive shaft
15
.
Rotation of the drive mechanism
46
is transmitted through the torque tube
52
to an output gearing mechanism
54
consisting of first and second planetary gearsets
55
and
56
. The first planetary gearset
55
comprises a third sun gear
57
attached to the torque tube
52
, a first pinion
58
supported for rotation on a mount member
60
fixed to a stationary case and meshing with the third sun gear
57
, and a first ring gear
59
in mesh with the first pinion
58
. The second planetary gearset
56
includes a fourth sun gear
61
attached to the torque tube
52
, a second pinion
62
supported for rotation to a carrier
64
, and a second ring gear
59
connected to the extension
14
of the input shaft
1
and meshing with the second pinion
62
. The first ring gear
59
of the first planetary gearset
55
and the carrier
64
of the second planetary gearset
56
extend downstream so as to be selectively connected to the output shaft
40
via either a high-range clutch
65
or low-range clutch
66
.
When engaging the high-range clutch
65
whereas disengaging the low-range clutch
66
, the transmission ratio becomes the high-range operation. In contrast, when the low-range clutch
6

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