Tire Pressure Monitor System Using Rotational Speed Signal from Wheel Speed Sensor of ABS System

摘要

Traveling with insufficient tire inflating pressure will lead to excessive fuel consumption, uneven wear of tires and worsening of vehicle stability and controllability. Since lowering of tire inflating pressure is caused rather by natural leak than by puncture, a system for detecting lowering of inflating pressure of each tire is needed. In view of such background, we have succeeded in developing a system of detecting lowering of inflating pressure independently for each tire according to the wheel speed sensor signal in the ABS (Anti-Lock Brake System). This system assumes lowering of tire spring constant as lowering of the inflating pressure by estimating the spring constant variation using an external disturbance observer, with attention paid to the tire spring constant having correlation with the tire inflating pressure. It, therefore, allows detection of not only tire puncture but also natural leak. Since existing sensors are used, it can be realized with little increase in cost.