A DESIGN FOR CONTINUOUSLY VARIABLE TRANSMISSION CONSISTING OF LINKS, CRANKS, CAMS, AND FREEWHEELS

Toshihiro Yukawa∗

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Keywords

Continuously variable transmission, fourbar linkage, slidercrank mechanism, freewheel, oneway clutch, cam, frictional force

Abstract

This paper describes a continuously variable transmission (CVT) consisting of links, cranks, cams, and freewheels. Generally, power transmission mechanism such as the CVT has been used in vehicles or construction machineries, etc. Conventional CVTs are mainly classified as belt-type or toroidal-type CVTs based on the difference between their fundamental conduction mechanisms. The proposed CVT consists of closed-loop linkages, three-dimensional cams, and irreversible mechanisms such as freewheels, and it does not depend on any frictional conduction forces in the mechanism. This CVT can provide high functions that create no noise, is durable, and offers high transmission efficiency. All units, in which each slider-crank mechanism is installed, are connected in parallel at both the input and output shafts in the CVT. On the output side, each crankshaft in each unit is connected mechanically at a common output axis through freewheels. The main purpose of this paper is to design the outer shape of the cam inside the CVT unit, design it for each gear ratio, and then build a CVT in which multiple units are arranged in parallel. In this CVT, the continuous rotation input from the input shaft can continuously rotate the output shaft regardless of the arbitrary gear ratio, and the output shaft rotates in proportion as the rotation speed of the input shaft in relation to the arbitrary gear ratio. In this paper, we derive a mathematical linkage model for the slider-crank mechanism installed in the CVT. In particular, we analyse the geometry of the relationship between the link mechanisms and the three-dimensional cam. As this conduction mechanism is not composed of frictional components, it provides high transmission efficiency.

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