| 摘要 |
It is an object of the present invention is to detect a tire air pressure indirectly, and to improve a precision in detection. A tire air pressure detecting device includes a speed sensor for outputting a signal corresponding to a rotational speed of a tire, and an electronic control unit which inputs the signal therein from the speed sensor to perform predetermined arithmetic operations. The electronic control unit calculates a wheel speed on the basis of the output signal of the speed sensor, and performs a frequency analysis for the calculated vehicle speed so as to derive the a resonance frequency of the unsprung mass in the upward, downward, forward and backward directions. Then, on the basis of this resonance frequency, the tire air pressure is detected. <IMAGE> |
