Toroidal continuously variable transmission

Details Toroidal continuously variable transmission Toroidal continuously variable transmission

2002-05-23

2004-05-04

Fenstermacher, David (Department: 3682)

Friction gear transmission systems or components

Friction gear includes idler engaging facing concave surfaces

Toroidal

C476S040000

Reexamination Certificate

active

06729997

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a toroidal continuously variable transmission for a vehicle, and specifically to a link support structure of a toroidal continuously variable transmission.
BACKGROUND ART
To meet demands for increased shift comfort, improved driveability, and reduced fuel consumption and exhaust emissions, there have been proposed and developed toroidal continuously variable transmissions often abbreviated to “toroidal CVTs”, in which a transmission ratio is steplessly variable within limits. On such toroidal CVTs, engine power (torque) is transmitted from an input disk to an output disk via a traction oil film formed between a power roller and each of the input and output disks, using a shearing force in the traction oil film at high contact pressure. The input and output disks coaxially oppose each other. Generally, a pair of power rollers are disposed between the input and output disks. One such toroidal CVT has been disclosed in Japanese Patent Provisional Publication Nos. 9-317837 (hereinafter is referred to as JP9-317837 corresponding to U.S. Pat. No. 5,893,815) and JP2001-182793 (corresponding to U.S. Patent Publication No. US2001/0016534 A1).
FIG. 8
shows a partial cutaway view of the front side of a so-called double cavity type toroidal CVT (disclosed in JP9-317837 corresponding to U.S. Pat. No. 5,893,815) that a first variator (a front toroidal CVT mechanism) and a second variator (a rear toroidal CVT mechanism) are set in tandem and coaxially arranged in the interior space of a toroidal CVT casing
1
. As shown in
FIG. 8
, the front toroidal CVT mechanism has a pair of trunnions
14
,
14
each serving as a power roller support for power roller
8
being in contact with a torus surface of each of the input and output disks under preload (under a loading force). In
FIG. 8
, the axis denoted by O
1
is a common rotation axis of the input and output disks, the axis denoted by O
2
is a trunnion axis, and the axis denoted by O
3
is a rotation axis of the power roller. Owing to the grip force (the loading force) acting on the power roller, there is a tendency for the power roller to be driven out from between the input and output disks. To avoid this, upper ends of trunnions
14
are mechanically linked to each other by means of an upper link
16
, while lower ends of trunnions
14
are mechanically linked to each other by means of a lower link. FIGS.
9
and
10
A-
10
B show a conventional link support structure as disclosed in JP9-317837 (corresponding to U.S. Pat. No. 5,893,815) or U.S. Pat. Publication No. US2001/0016534 A1. As clearly shown in
FIG. 9
, upper link
16
is formed therein with two pairs of trunnion support holes h
1
, h
1
, h
1
, h
1
, each pair h
1
, h
1
associated with the two trunnions included in one of the first and second variators. A substantially square hole h
2
is formed in the upper link and located midway between upper-left and lower-left trunnion support holes h
1
, h
1
, supporting the trunnion pair
14
,
14
included in the first variator. In the same manner, a substantially square hole h
2
is formed in the upper link and located midway between upper-right and lower-right trunnion support holes h
1
, h
1
supporting the trunnion pair
14
,
14
included in the second variator. Upper link
16
is pivotally supported by way of a pair of link posts or a pair of link supports
11
,
11
, passing through the respective square hole h
2
, h
2
. In
FIG. 9
, reference sign h
3
denotes a central rectangular hole, which is provided to avoid the interference between the upper link and the output disks of the first-and second variators. Link support
11
is securely connected to toroidal CVT casing
1
by means of a bolt A. Concretely, upper link
16
is pivotally supported by way of two pairs of pins
12
a
,
12
a
,
12
a
,
12
a
, which are aligned with each other in the direction of common rotation axis O
1
of the input and output disks. The lower link support structure is the same as the upper link.
FIG. 10A
is a side view of the upper link portion, taken in the direction of common rotation axis O
1
of the input and output disks.
FIG. 10B
shows analytical mechanics (vector mechanics) for a force &ggr; applied from the right-hand trunnion to the upper link and a reaction force &dgr; applied from the left-hand trunnion to the upper link and a force &egr; applied to pin
12
a
, during transmission-ratio changing. As is generally known, during ratio changing, in order to obtain a desired transmission ratio determined based on the magnitude of a gyration angle of the power roller, each power roller is vertically shifted or displaced from a neutral position (anon-ratio-changing position shown in
FIG. 10A
) at which power-roller rotation axis O
3
intersects the center of rotation (common rotation axis O
1
) of the input and output disks. The shifting operation of the power roller pair is created by shifting one of the trunnion pair
14
,
14
in a first direction &agr; of trunnion axis O
2
perpendicular to power-roller rotation axis O
3
via a hydraulic servo mechanism with a servo piston, and by shifting the other trunnion in a second direction &bgr; opposite to the first direction &agr; via a hydraulic servo mechanism in synchronism with the shifting operation of the one trunnion. That is, the two trunnions are shifted in phase in the opposite trunnion-axis directions &agr; and &bgr; during ratio changing. A jointed portion between each of the trunnions and the upper link must be designed to permit the previously-noted vertical displacement or offset of the power roller from the neutral position and a change of the gyration angle of the power roller. Thus, as shown in
FIGS. 10A and 10B
, the jointed portion is constructed as a combination joint comprised of a bearing B fitted to the upper end portion of trunnion
14
and a spherical joint C fitted onto the bearing B. As best seen in
FIG. 9
, the conventional link support structure is a pin-support structure composed of pins
12
a
,
12
a
,
12
a
,
12
a
axially aligned with each other in the direction of common rotation axis O
1
. In case of such a pin-support structure, pins
12
a
,
12
a
,
12
a
,
12
a
function to restrict translating motions in three different directions, namely a longitudinal direction along common rotation axis O
1
of the input and output disks, a vertical direction along trunnion axis O
2
, and a lateral direction (a left-and-right direction) normal to both the longitudinal direction along input/output-disk rotation axis O
1
and the vertical direction along trunnion axis O
2
. The conventional pin-support structure has several drawbacks discussed hereunder.
As can be seen in
FIG. 10B
, during ratio changing that trunnions are shifted in phase in the opposite directions &agr; and &bgr;, there is a tendency that trunnion
14
is relatively inclined with respect to upper link
16
with an intersection angle, which is an angle of deflection at the intersection point between the straights of the upper link and the trunnion. Assuming that the right-hand trunnion of
FIG. 10B
is brought into spot-contact with the upper link at an interference point or a contact point f with an intersection angle during ratio changing, a force &ggr; acts on the upper link via contact point f. In case of the pin-support structure that the central portion of the upper link is pin-connected to toroidal CVT casing
1
, pin
12
a
serves as a fulcrum point of a lever, contact point f serves as a power point (or a point of application), and a frictional contact portion between the inner peripheral wall surface of the support hole of upper link
16
and a combination joint (in particular, a spherical joint C) of a jointed portion between the left-hand trunnion of FIG.
10
B and upper link
16
serves as a point of action. Owing to force &ggr; acting on the upper link via contact point f, a reaction force &dgr; acts on the frictional contact portion (serving as a point of action) between upper link
16
and the left-hand trunnion. On the other hand,

Affiliated with

Also associated with

Rating

Toroidal continuously variable transmission does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Toroidal continuously variable transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Toroidal continuously variable transmission will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3259063