Abstract: For use with trucks, aircraft and other motor vehicles, circuit apparatus signals, from within a pneumatic tire to a display near the operator, an abnormal tire pressure or temperature. A monitoring transmitter within the tire utilizes a negative coefficient thermistor maintained in thermal contact with the tire to sense an abnormal high temperature, and a bellows-type pressure sensor, internally pressurized to approximately the normal tire pressure, to sense abnormal high or low pressures. If one of these abnormal conditions is sensed, power is supplied from a long-lifetime battery to an FM transmitter modulated by a different selected frequency for each tire, selected by a potentiometer marked for each frequency. These circuit elements are on a circuit board secured to the inside of the tire by an overlaying elastic adhesive material which absorbs shock and thermally insulates the thermistor from the air within the tire.
April 27, 1979
Date of Patent:
June 8, 1982
John D. Frazier, Wilmur G. Grandfield, Michael G. Brainerd