Kikuo Okamura

Study of Transmission Performance of 2K-H Type CVT

The purpose of this study is to improve the transfer performance of 2K-H type CVT (Continuously Variable Transmission) by changing of an axial thrust generating unit and a shape of rolling element. An efficiency of CVT is obtained from relation between axial thrust and output torque by the experiment. In the experiment, compared with a compression spring, the use of the loading cam was useful for the axial thrust generating unit. When a contact area of CVT was changed by the shape of rolling element, the efficiency was influenced by aspect ratio of the contact area. As this result, a maximum efficiency of 2K-H type CVT was attained by an optimum loading cam and a minimum aspect ratio.

Power Transfer Characteristic of Ring-Cone 3K Type CVT

In this paper, we discuss an experimental and theoretical investigation of the basic performance on the transmission efficiency of 3K type CVT with a ring and cones. The analysis was carried out using a formula on efficiency of the planetary gear and a theoretical formula on the contact area which is based on elasto-plasticity model of traction fluid. The transmission efficiency was calculated by the experimental results obtained from the rotations and the torques on the input shaft and the output shaft. As a result, we found the theoretical result corresponded to the experimental result on the transmission efficiency of CVT. Moreover, the efficiency decreased due to the influence of the bearing loss, when the load torque decreased. The speed ratio, which is calculated by considering the slip on the contact area, was showing a tendency to decrease with the increase of the load torque. It was also confirmed that an analysis method was valid with the calculation of the power transmission efficiency of 3K type CVT.