| 摘要 |
<p>An apparatus and method for detecting a decrease of the air pressure in a tire for a four-wheel vehicle. Letting the rotational angular velocities of four tires are F1, F2, F3, F4, a judgement value dF is expressed by the following equation (A): dF=(F1+F4)/(F2+F3). The judgement value dF is a ratio of the sum (F1+F4) of the rotational angular velocities of one pair of tires on a diagonal to that (F2+F3) of the rotational angular velocities of the other pair. When the air pressures in the four tires are all normal, (F1+F4)=(F2+F3), so that dF=1. When the pressure in any one of the tires decreases, dF¸1. Therefore, when the judgement value is compared with a predetermined value, a decrease in the air pressure in a tire is detected.</p> |
