Disk for toroidal type continuously variable transmission

Abstract

The disk has a traction surface having a concave-arc-shaped cross section which is interposed between a small diameter end portion and a large diameter end portion. In the central portion of the end face of the disk on the small diameter end portion side, there is formed a through hole which extends through the disk up to the large diameter end portion side end face of the disk, while the inner peripheral surface of the through hole is used as an inside diameter surface of the disk. Here, when, among metal flows existing in the disk, a metal flow, which has such a positional relationship with respect to the surface of the disk that an angle θ formed between a metal flow on the traction surface side and the tangent of the traction surface is smaller than or equal to 30 degrees, is defined as a “metal flow along the disk surface”, the disk is structured such that the “metal flow along the disk surface” exists at least in the traction surface.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a disk for use in a toroidal type continuously variable transmission which can be used in vehicles, various kinds of industrial machines, and the like.[0003]2. Description of the Related Art[0004]A toroidal type continuously variable transmission comprises, for example, as shown in FIG. 15, input and output disks a and b which are disposed concentrically with each other, and a power roller c which is interposed between the respective traction surfaces f and i of the input and output disks a and b1.[0005]In the input disk a, between the small diameter end portion d and large diameter portion e thereof, there is formed a traction surface f the cross section of which provides a concave-arc shape and, in the output disk b1, similarly, between the small diameter end portion g and large diameter portion h thereof, there is formed a traction surface i the cross section of which provides a conca...

AI Technical Summary

Benefits of technology

[0011]The present invention aims at eliminating the drawbacks found in the disks used in the conventional toroidal type continuously variable transmission. Accordingly, it is an object of the invention to provide a disk for use in a toroidal type continuously variable transmission which not only can reduce the production cost thereof but also can realize a long life.

Problems solved by technology

However, in the conventional method for manufacturing the input and output disks a and b1, the yield of the material is poor and it takes long time to cut or shave the material, with the result that the production costs of the input and output disks a and b1 are soaring.

Also, because a metal flow (the flow of structure) k is arranged along the axial direction of the disk, in the traction surfaces f and i with which the power roller c is frictionally engaged with a large pressure, the metal flow k comes to an end and, actually, does not extend along the traction surfaces f and i. As a result of this, not only the material is easy to peel off in the portions of the traction surfaces f and i with which the power roller c is frictionally engaged, but also an impact crack or a fatigue crack is easy to occur in the input and output disks a and b starting at the broken portions of the metal flow k, thereby providing an obstacle to the long lives of the input and output disks a and b1.

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