Frictional roller type continuously variable transmission

Details Frictional roller type continuously variable transmission Frictional roller type continuously variable transmission

1999-07-08

2001-03-06

Herrmann, Allan D. (Department: 3682)

Friction gear transmission systems or components

Fluid control

Of toroidal transmission

C476S042000

Reexamination Certificate

active

06196945

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a frictional roller type continuously variable transmission of which a typical example is a toroidal continuously variable transmission.
BACKGROUND TO THE INVENTION
A frictional roller type continuously variable transmission used as a toroidal continuously variable transmission is known for example by published application Jikkai-Sho-63-92859 in Japan.
A toroidal continuously variable transmission provides power to a pair of power rollers between an input disk and an output disk. The rotation of the input disk is transmitted to the output disk through the power rollers by a frictional force. Since the power rollers are gripped by a strong force which corresponds to the transmitted torque from the input and output disks, a large thrust force in the rotation axis direction of the power rollers is applied to the power rollers by the input and output disks.
The power rollers are supported by trunnions. Since the upper and lower section of the trunnion axis of the pair of trunnions are mutually connected by an upper link and a lower link, displacement due to the thrust force mentioned above is limited. However the trunnions deform about the points of support created by the respective links.
SUMMARY OF THE INVENTION
A servo-piston is mounted on the trunnion axis which comprises a hydraulic pressure servo-mechanism for displacing the trunnions in an axial direction and thus varying the angle of gyration of the power rollers. However when the trunnion axis deforms, the servo-piston also inclines and comes into contact with the inner peripheral face of the cylinder. Thus the sliding face and seal member may be damaged. In such a case, the movement of the servo-piston may be impaired or an oil leakage may occur. As a result, there will cause of reductions in speed ratio control performance.
The present invention has the object of preventing the piston sliding section from damage or an oil leakage even when the piston sliding section inclines as a result of deformation of the trunnion.
In order to achieve the above object the present invention provides a frictional roller type variable transmission. The transmission comprises a pair of power rollers gripped between an input disk and an output disk, the power rollers being able to gyrate, trunnions supporting the power rollers through an eccentric shaft and being slidable in a pivot axial direction orthogonal to the rotational axis of the power rollers, a link mechanism connecting upper and lower sections of each trunnion to support a thrust force applied to the power rollers due to a gripping force of the input disk and the output disk, a hydraulic cylinder provided with a servo-piston connected to a trunnion shaft so that said trunnion displaces in the pivot axial direction, a seal member which seals a hydraulic pressure supplied into the hydraulic cylinder housed in each sliding section of the hydraulic cylinder, the sliding sections diposed both ends of the servo-piston pass through a cylinder body, and a cylindrical gap being formed between a piston sliding outer periphery and a cylinder sliding inner periphery in the one of sliding sections which opposed to the link mechanism and the cylindrical gap positioned outwardly with respect to the seal member.
The details as well as other features and advantages of the invention are set forth in the remainder of the specification and are shown in the accompanying drawings.


REFERENCES:
patent: 4905529 (1990-03-01), Nakano
patent: 5538483 (1996-07-01), Kobayashi et al.
patent: 63-92859 (1988-06-01), None
patent: 7-217716 (1995-08-01), None

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