Forward parameter optimization design for actuator of electromechanical continuously variable transmission

Abstract

An electromechanical continuously variable transmission (EMCVT) with an actuator containing two direct current (DC) motors is proposed to improve the transmission efficiency of a continuously variable transmission (CVT) by reducing the power consumed by the CVT actuator. To enhance the EMCVT efficiency, the ratio and driven pulley clamping force are adjusted using an electromechanical actuator. It is required that the adjustable range of the driven pulley clamping force of the EMCVT is maximized and the operating power of the DC motors in the actuator is minimized. However, this adjustable range is limited when the actuator is designed for the maximum required driven pulley clamping force. To ameliorate this issue, the electromechanical actuator is optimized in this paper. The structure and operating principles of the EMCVT are illustrated, and the main actuator part models are built. Accordingly, the design principle of the main actuator parts is determined. The required clamping force for four standard driving cycles is considered, and the structural parameters of Belleville springs in the actuator are optimized using a genetic algorithm. Two DC motors are suitably selected, and the mechanical transmission system of the actuator is determined. The optimization results show that the adjustable range of the driven pulley clamping force is increased by over 80% for a high CVT ratio and that the energy consumed by the actuator is reduced for ECE and EUDC driving cycles by ~ 56% and ~ 28%, respectively, as compared to the energy consumed by the actuator before optimization.