Patent ID: 7305318
Filing Date: 2007-12-04
Classification: B60C

Abstract:
1. A process of detecting decrease in tire air-pressure based on wheel rotational velocities obtained from tires mounted on a vehicle, which comprises the steps of: detecting wheel rotational velocities of the respective tires; repeatedly performing a relative comparison between the detected wheel rotational velocities to thereby obtain judgment values for decrease in tire air-pressure; storing the judgment values in an average preparation buffer; calculating an average value of the judgment values stored in the average preparation buffer; writing the average value and the number of the judgment values into a nonvolatile memory at a predetermined timing; expanding the average value that is written in the nonvolatile memory into the average preparation buffer in duplicate corresponding to the number of judgment values; calculating a subsequent average value of a prescribed number of judgment values that are stored in the average preparation buffer; comparing the subsequent average value with a predetermined threshold value, to thereby obtain a judgment of whether or not a decrease in tire air-pressure has occurred; and providing notification of the judgment of whether or not a decrease in tire air-pressure has occurred.