Tire pressure detecting apparatus for vehicle.

摘要

A tire pressure detecting portion includes a housing, provided within the tire, within which a piezoelectric element is provided so as to be deformed by the tire pressure, whereby the capacity of said piezoelectric element is changed in accordance with its deformation. The piezoelectric element is electrically connected with a first coil disposed within said tire. The first coil (13) is electromagnetically coupled with an excitation coil and a receiving coil, both of which are provided in the vehicle. The excitation coil is electrically connected with an oscillator for supplying the excitation coil with an excitation voltage whose frequency is changed with a predetermined range including a resonant frequency. The receiving coil is electrically connected with resonant frequency determining means. The resonant frequency determining means determines that the received voltage has the resonant frequency. As a result of such determination, pressure determining means determines the corresponding tire pressure based on a data map showing the relationship between said resonant frequency and said tire pressure.