Patent ID: 6407661
Filing Date: 2002-06-18
Classification: B60C

Abstract:
An apparatus for alarming decrease in tire air-pressure which alarms decrease of internal pressure of a tire on the basis of a rotational information obtained by tires attached to a four-wheeled vehicle, comprising:rotational information detecting means for detecting a rotational information of each of the tires; memory means for storing the rotational information of each of the tires; calculation processing means for calculating a reciprocal number of a turning radius from the rotational information of the tires attached to a driving shaft among the rotational information of the respective tires and calculating a judged value from the rotational information of the respective tires; first judging means for comparing the judged value with a reference value at every regions of the turning radius on the basis of a relation between the reciprocal number of the turning radius and the judged valve so as to judge decrease in internal pressure; and second judging means for canceling a judgement of decrease of internal pressure when a difference between the judged value in the right turning region and the judged value in the left turning region is different from a difference between a reference judged value in the right turning region and a reference judged value in the left turning region which are obtained at a time of initializing run.