Paper Title
Change of Transmitting Properties of Rubber V-Belt for CVT According to Difference of Stiffness

Abstract
The objective of this study is to clarify the influence of bending deformation of belt by thrust force in pulley groove on transmitting properties of CVT rubber V-belt for motorcycles. The power generated by AC motor was transmitted from the drive shaft to the driven shaft through the CVT unit. The thrust force of the driven pulley was applied by oil-pressure generated by the oil pump, and width of driving pulley was controlled by motor. Pulley thrust force, rotating speed and applied torque was measured by load cell, tachometers, and torque meters, respectively. The bending deformation of belt and pitch radius of belt during wrapping on driving pulley was measured by laser displacement sensor. Transmitting properties of low stiffness belt and that of high stiffness belt (transmitting efficiency, slip ratio) was evaluated.Effective wrapping of the belt in pulley groove was enlarged and transmitting efficiency was increased when bending stiffness in longitudinal direction was low.Radial displacement of the belt due to bending deformation by thrust force in pulley groove was reduced and slip ratio was decreased when bending stiffness in width direction was high, even when applied torque was changed. It was found that high transmitting properties of CVT rubber V-belt were obtained when the bending stiffness in the longitudinal direction of belt was low but bending stiffness in the width direction was high. Keywords - CVT(continuously variable transmission), Rubber V-belt, Transmitting properties, Transmitting efficiency, Slip ratio, Stiffness