To improve the quietness of electric vehicles and self-driving vehicles, it is an urgent task to construct an efficient method for reducing road noise and drumming noise generated by the road surface while driving. On the other hand, due to the increase in wheel diameter and improvement in braking force recently, the resonance tonal noise generated around the wheel at extremely low speed owing to the frictional vibration generated in the brake disc has become one of the problems. This resonance impairs the comfortability in the vehicle cabin, and there is a possibility that drivers or occupants recognize it as an abnormal noise or malfunction of the vehicle. Research on the noise generation from the disk brake system of the vehicle have been carried out by many researchers but there are few researches focused on the noise generation by the resonance of the wheel. In this study, we used a commercial vehicle and measured the tonal noise generated around the wheel when the vehicle was moving low speed and the braking force was slightly working. Further, we simultaneously measured the vibrational acceleration on the wheel surface and performed modal analysis and operational transfer path analysis to investigate the mechanism of the noise generation. Results showed that the low-frequency tonal noise was emitted firstly and then the higher-frequency one was emitted. It is also found that the lower- and higher-one were generated with corresponding to the vibrational acceleration of the wheel near the ground and near the brake caliper.

Wheel,Automobile;,Tonal noise;,OTPA;,Brake