Patent ID: 8997561
Filing Date: 2015-04-07
Classification: B60C,G01M

Abstract:
1. An apparatus for detecting a decrease in tire pressure based on a resonance frequency of a tire installed in a vehicle, comprising: rotation information detection means for detecting rotation information of the tire, resonance frequency estimate means for estimating the resonance frequency of the tire from the rotation information of the tire, and judgment means for judging the decrease in the tire pressure by comparison between the resonance frequency estimated by the resonance frequency estimate means and a reference frequency preliminarily determined by learning at the time of initialization, wherein an effective speed region when the reference frequency is determined at the time of the initialization is a first speed and less, the first speed being the upper limit of the effective speed region, and wherein the apparatus further comprises effective speed region change means for extending the upper limit of the effective speed region from the first speed to a second speed which is larger than the first speed at the time of shifting to judgment of the decrease in the pressure after learning of the reference frequency is completed.