Abstract:The continuously variable transmission (CVT) is an ideal solution of mechanical transmission. As the development of modern industry and vehicle technology, the CVT is expected to realize the adaptive shifting when the load changes. For the roller flat disk CVT, which is a kind of traction CVT that the output shaft is coaxial with the shifting direction of the shifting component, a screw-spring adaptive shifting mechanism (ASM) of load torque was proposed and the dynamic analysis was conducted. Firstly, the structure model of roller flat disk CVT with screw-spring ASM was described. Then, the kinematic model was established by using analytical method, the contact model was established with Hertz contact theory, and the dynamic model was conducted through the separation analysis method, respectively. Finally, the change regular of side-slip force between roller and flat disk, as well as the transformation law of roller during adaptive shifting of different load torque were mainly analyzed, and the effect of balance spring stiffness coefficient on shifting process was also studied. Simulation experiment was also carried out to verify the transformation law of roller during the adaptive shifting process. The results showed that: In the process of adaptive shifting, the side-slip force is basically constant when the side-slip coefficient is higher than 0.55; The adaptive shifting process is actually a vibration process, and the stiffness coefficient and the load variety could directly affect the dynamic response characteristics; When the initial load conditions are different, the same output load only affects the amplitude of the vibration, but there is no significant effect on the offset of the roller in the speed stabilization state. The simulation results of the transformation law during adaptive shifting process are consistent with the trend of the calculated results, but there is a clear difference between the stable time. The simulation results are closer to the actual situation.