Toroidal continuously variable transmission

Details Toroidal continuously variable transmission Toroidal continuously variable transmission

1999-08-25

2001-05-15

Estremsky, Sherry (Department: 3681)

Friction gear transmission systems or components

Friction gear includes idler engaging facing concave surfaces

Toroidal

C476S040000

Reexamination Certificate

active

06231473

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a toroidal continuously variable transmission for vehicles.
BACKGROUND OF THE INVENTION
Tokkai Hei 7-158711 published by the Japanese Patent Office in 1995 discloses a toroidal continuously variable transmission (toroidal CVT) for vehicles wherein the ratio of a rotation speed of an input disk relative to the rotation speed of an output disk, i.e., a speed ratio, is continuously varied by varying the gyration angles of a pair of power rollers gripped between the input disk and the output disk.
The power rollers are respectively supported by trunnions. When the trunnions are respectively displaced in an axial direction by hydraulic actuators, the gyration angles of the power rollers vary accordingly.
SUMMARY OF THE INVENTION
In order to grip the power rollers between the input disk and the output disk in the toroidal CVT, a thrust load must be made to act on the input disk and output disk. In general, the thrust load in proportion to the torque input into the transmission is generated by loading cams.
Further, as the loading cams do not generate the thrust load when the torque input into the transmission is zero, a preloading mechanism is provided apart from the loading cams, and a predetermined preload is exerted on the input disk and output disk. In the aforesaid prior art, the preloadig mechanism comprises two belleville springs (a pair of coned disk springs) which directly push the input disk.
However, the position of the input disk in the axial direction changes according to the gyration angles of the power rollers inserted between the input disk and output disk. In the position in which the input disk has retreated to its maximum extent, a large compression force acts on the belleville springs and the springs come into close contact
If the input torque becomes large in this state, the input disk deforms and the belleville springs and input disk rub against each other. The belleville springs will wear out, if such a phenomenon frequently occurs.
It is therefore an object of this invention to prevent a large force from acting on the belleville springs of the preloading mechanism, and to prevent the belleville springs from rubbing against a disk so as to prevent wear of the belleville springs.
In order to achieve the above object, this invention provides a toroidal continuously variable transmission comprising an input disk, an output disk, a power roller gripped between the input disk and the output disk, a loading mechanism which generates a thrust load according to an input torque input into the transmission, and applies the thrust load to the disks, an elastic member which comes in contact with a specific disk of the disks and applies a preload to the disks and a limiting member which limits a displacement of the specific disk in a compressing direction of the elastic member.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.


REFERENCES:
patent: 4893517 (1990-01-01), Nakano
patent: 5027669 (1991-07-01), Nakano
patent: 5651750 (1997-07-01), Imanishi et al.
patent: 5679090 (1997-10-01), Imanishi
patent: 5984826 (1999-11-01), Nakano
patent: 7-158711 (1995-06-01), None
patent: 41-1201254 (1999-07-01), None

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