| 摘要 |
<p>According to the tire air-pressure reduction detecting apparatus and method of the present invention, when a vehicle actually travels, the detected rotational angular speeds Fi of the tires Wi are multiplied by correction coefficients Ci to correct the initial differences (Step N2), the vehicle speed V0 is calculated based on rotational angular speeds Fi0 thus obtained (Step N3), and the speed V0 is put in a formula of relationship f(V) to obtain a front/rear wheel ratio f(V0) corresponding to the speed V0 (Step N4). 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 front/rear wheel ratio 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 (Step N5). The products are put in a judging formula for detecting a reduction in the air pressure of a tire Wi, thereby to calculate a judgement value D. When D satisfies the following conditions: D < - DTH1 or D > DTH2 it is judged that there is a tire Wi reduced in air pressure. Such a 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 the vehicle speed or forward/backward acceleration. <IMAGE></p> |
