SYSTEM FOR MONITORING TIRE AIR PRESSURE

摘要

A system capable of monitoring the air pressure within the tire without providing a pressure sensor, capable of transmitting a detection signal through a wire, having no influence of noise, and highly reliable because of stable signal transmission. Bearings adapted for use in wheels and provided with rotation detection devices (1) for detecting the rotational speed of the rotating rings of the bearings are used as the bearings (2) for supporting the wheels (21) of a vehicle. The system is provided with an air pressure estimation means (24) for estimating the air pressure within the tires by comparing with each other rotational speed signals outputted from the rotation detection devices (1) of the bearings (2). The rotation detection devices (1) are provided with multiplication means (4) for multiplying output pulses outputted from sensors (3).