Apparatus and method for alarming decrease in tire air-pressure

Abstract

An apparatus for alarming decrease in tire air-pressure which detects the decrease in internal pressure of the tire based on wheel speed information obtained from wheels of a vehicle and accordingly alarms a driver. The apparatus comprises: a wheel speed information detecting means, a memory means for storing the wheel speed information of the respective tires, a calculating means for calculating a judged value based on a vehicle velocity and wheel speed information, and a judging means for determining a decrease in tire air-pressure based on correlation of the vehicle velocity and an outer diameter of the tire at the time of performing high-speed running. It is possible to determine a decompression of a tire based on the correlation also in case the judged value will not become large owing to increased influence of centrifugal force during high-speed running even though a tire is in a decompressed condition.

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