The development of hybrid and electric vehicles in recent years has contributed to the vehicle in-cabin quietness; there is further need to reduce brake noises. Especially, the brake moan, low frequency noise which is audible inside the vehicle. It is known from experience that moan is the coupling of brake and suspension modes. However, the generating mechanism has not been clarified up to now. By analysing the natural vibration modes of the brake and suspension, we found the generating mechanism and examined the noise reduction technology.

Naotaka Nishida, Toru Matsushima, TOYOTA MOTOR CORPORATION, JAPAN