| 摘要 |
According to the tire air-pressure reduction detecting apparatus and method of the present invention, when a vehicle travels, the detected rotational angular speeds Fi of the tires Wi are multiplied by correction coefficients Ci to correct initial differences. Vehicle speed V0 is calculated based on angular speeds Fi0, and is put in a relationship formula f(V) to obtain a front/rear wheel ration f(V0) corresponding to the speed V0. Based on the front/rear wheel ratio f(V1) corresponding to a speed V1 at which the correction coefficients Ci have been obtained, and the ration f(V0), there is obtained a variation of the front/rear wheel ratio f(V0)/f(V1), by which rotational angular speeds F3, F4 are then multiplied. The products are used for detecting a reduction in the air pressure of a tire Wi, thereby to calculate a judgement value D. When D satisfies the conditions: D<-DTH1 or D>DTH2 it is judged that there is a tire Wi with reduced air pressure. Such processing eliminates the influence of speed variations or forward/backward acceleration, such that the rotational angular speeds of the front and rear tires can be obtained more accurately. It is therefore possible to detect a reduction in air pressure with high precision regardless of vehicle speed or forward/backward acceleration.
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