PURPOSE: To provide a device which can estimate and inform running capability time and distance from a tendency of reduction of tire pressure when a tire is punctured.
CONSTITUTION: Tire pressure is detected at a tire pressure detection section 1. The tire pressure detection section 1 may be constituted out of a device which detects tire pressure directly or in such a way that change amount of spring constant of torsional spring between a rim side section and a belt side section of a wheel is assumed by a disturbance observer and tire pressure is assumed based on the change amount. Whether reduction gradient of tire pressure exceeds the reference value of an air leak judgment reference value memory 74 or not is judged in an air leak judging section 70. If it exceeds the reference value, running capability time and running capability distance are judged based on reduction gradient of tire pressure, car speed detected by a car speed detection section 4, and an allowable lower limit pressure value table 76 and displayed in a running capability amount display section 5 in a running capability amount judging section 72.
KOJIMA HIROYOSHI
KAWAI HIROYUKI
HIRAIWA NOBUO
ASANO KATSUHIRO
UMENO KOJI
TAKAHASHI TOSHIMICHI
TOYOTA CENTRAL RES & DEV