Patent ID: 8577540
Filing Date: 2013-11-05
Classification: B60C

Abstract:
1. A method for detecting a tire having a decreased internal pressure by making a relative comparison of wheel speeds of tires attached to the respective wheels of a vehicle, comprising the steps of: detecting wheel rotation information of the respective tires of the vehicle; calculating, using a Central Processing Unit (CPU), wheel speeds based on the detected wheel rotation information; calculating a decreased pressure determination value by making a relative comparison of the calculated wheel speeds; and determining a tire having a decreased internal pressure when the resultant decreased pressure determination value exceeds a predetermined threshold value, wherein the method further comprises a step of setting a threshold value, in which the predetermined threshold value is set, during initialization, based on a decreased pressure sensitivity calculated from a relation between a load sensitivity and a decreased pressure sensitivity during vehicle turning that is calculated in advance in a calibration phase and a load sensitivity obtained through a turning running during initialization, and wherein the load sensitivity is calculated based on a relational expression between a ratio of the dynamic loaded radius change due to the load shift during turning to the dynamic loaded radius, the ratio being calculated based on a yaw rate and a lateral acceleration obtained from a yaw rate sensor and a lateral acceleration sensor mounted in the vehicle and wheel speeds of left and right wheels of the vehicle, and a lateral acceleration.