Tire pressure detector for vehicle, determines air pressure reduction based on deviation in resonant frequencies of vibration component in wheel speed signal, obtained with respect to pneumatic pressure variation of tire

摘要

The filters (42,43) extract different resonant frequencies of vibration component in wheel speed signal, with respect to pneumatic pressure variation of tire, according to the temperature change in the tire. A determination unit (47) determines air pressure reduction based on the comparison of resonant frequency deviation and threshold value.