In-wheel drive system design with dynamic vibration absorption based on the adaptive transmission mechanism

The extra unsprung mass introduced by the propulsion motors becomes an unavoidable issue for electric wheel drive systems, resulting in deteriorated ride comfort and tire adhesion stability. This study presents an innovative wheel drive system based on the dynamic vibration absorber (DVA) to suppress the unsprung mass vibration, improving the suspension dynamic performance. Specifically, we apply the principle of adaptive transmission to generate an extra degree of freedom (DoF), enabling the propulsion motor to work as the DVA. Innovative solutions with different topologies are exploited and an appropriate one is selected for a specific chassis platform. Based on the quarter-suspension dynamics with 3 DoF, the optimal design regarding the component sizing and stiffness/damping characteristics of unsprung mass suspension is carried out to minimize the vertical body acceleration and dynamic tire load through the genetic algorithm. In practical application, bench tests of the prototype prove that the proposed electric wheel drive system has reasonable driving efficiency and torque tracking performance, which verifies the feasibility of the proposed structure.