INITIAL CORRECTION FACTOR COMPUTING APPARATUS AND APPARATUS UTILIZING THE SAME

摘要

An apparatus for computing correction factors for correcting the output from a rotational frequency mechanism which is adapted to detect the rotational frequency of a tire fixed to a vehicle, and a slip percentage calculating apparatus and a tire pressure decrease detecting apparatus which utilize such a computing apparatus. In response to the operation of an initialization switch during an experimental linear coasting of a vehicle, the rotational frequency of a tire is detected. An initial correction factor is determined on the basis of this rotational frequency. This initial correction factor is stored in E<2>PROM. When the vehicle travels normally, the rotational frequency is initially corrected on the basis of the initial correction factor (at S2). The slip percentage is calculated on the basis of the initially corrected rotational frequency (at S3). A judgement value required to detect a decrease in the tire pressure is corrected on the basis of the slip ratio (at S9). Since an initial correction factor representative of only a relative difference between the effective rolling radii of the tires is obtained, the initial difference is eliminated accurately from the rotational frequency.