Evaluation of Influence of Motorized Wheels on Contact Force and Comfort for Electric Vehicle

Volatile oil prices and increased environmental sensitivity together with political concerns have moved the attention of governments, automobile manufacturers and customers to alternative power trains. From the actual point of view the most promising concepts for future passenger cars are based on the conversion of electrical into mechanical energy. In-wheel motors are an interesting concept towards vehicle electrification that provides also high potentials to improve vehicle dynamics and handling. Nevertheless in-wheel motors increase the unsprung mass worsening vehicle comfort and safety. All kinds of motorized-wheel structures are analyzed. For the unitary motorized wheel, since increasing the unsprung mass of vehicle, it adds adverse effects on the vehicle road holding performance and vehicle comfortableness. To decrease the adverse effect for unsprung mass increasing, a method by attaching the motor in the wheel through springs and dampers of exclusive use is brought out. It is verified that the vibration of EV with suspended-motor motorized-wheel is better than the EV with detached-motorized wheel. For high cost of suspended in-wheel motor, The effect of increasing of unsprung mass by using integral motor is analyzed by simulation with whole vehicle model. The more unsprung mass of integral motor deteriorates the vehicle comfort and vibration performance at low excitation frequency of road. But it is improved by using integral motor at higher excitation frequency of road, while unsprung mass is increased by using integral motor. The fluctuation amplitude of vibration at high frequency is much more big than at low frequency. In this view, the conclusion that in-wheel motor integrated into wheels is acceptable structural concept for electric vehicle with motorized wheels with lower cost than suspended in-wheel motor is achieved