Wireless sensor monitors tire pressure

July 12, 2001
A relatively recent U.


A relatively recent U.S. law (H.R. 5164) mandates that new cars soon be equipped with devices that inform drivers of the pressure in a car or truck's tires. Schrader Electronics is ready with its remote tire-pressure monitoring system. It consists of four tire-valve mounted sensors and transmitters, four detectors, and an onboard receiver. The sensors measure tire pressure, send that data to the nearest detector, which transfers the information on to the receiver and instrument cluster for processing and display. Detectors mount in each wheel well. An auto-rotation feature reconfigures the system whenever a tire changes position, such as after rotation or when new tires are mounted. This means the detector locates it assigned transmitter and continued to monitor pressure without manual reprogramming.

The sensors weigh 34 g, and have a 10-yr battery and 150,000-mile life. They measure pressures up to 150 psi with 0.2-psi resolution and 2% accuracy. The receiver compensates for barometric pressure and altitude changes, and collects data from all wheels whether the vehicle is moving or stationary.

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