Transmission efficiency of a high speed half-toroidal CVT.

A high speed half-toroidal continuously variable power transmission, CVT, has been developed. The transmission consists of the CVT with a ratio range from 2.0 to 0.5 and of a final reduction gear-set of 4.78. Some design features of the CVT are minimum spin on the traction contact, application of ceramic materials to thrust ball bearings and loading-cam rollers, and 21 MPa electro hydraulic speed control servomechanism for keeping the output-shaft rotational speed at 3000 rpm against input rotational speed changes from 10000 to 20500 rpm and load torque from 0 to 175 Nm. The CVT works at a speed transmission efficiency of 98% and a torque transmission efficiency of 85% in whole input speed ranges. This paper describes that the experimental micro-slip can be predicted by the theoretical spin analysis.