| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-precision tire pneumatic pressure detection device without using temperature information. SOLUTION: Signals near 15 Hz and 40 Hz are respectively extracted with first and second filter parts 42, 43 from a wheel speed signal which a wheel speed calculation part 41 calculates by a signal from a wheel speed sensor 3a. Respective signals extract first and second resonance frequency of a peak frequency with the first and second resonance frequency parts. A deviationΔF between the extracted first and second resonance frequency is calculated in a frequency deviation calculation part 46, and when the difference from an initial valueΔF0 of the deviation in normal tire pneumatic pressure pre-memorized in a initial value memory part 48, exceeds a predetermined threshold, the device determines at a determining part 47 the lowering of the tire pneumatic pressure, and raises an alarm to a driver with an alarm device 5. COPYRIGHT: (C)2004,JPO
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