Abstract: The tire pressure, speed and acceleration monitoring system of the present invention has a transducer mounted to the wheel of a motor vehicle and a controller mounted to a non-rotating part of the vehicle. The transducer is passive and receives its power from an interrogation signal from the controller. The transducer replies with a pressure signal. The tire pressure may be frequency encoded. This is accomplished by having a resonant circuit whose resonant frequency depends on the tire pressure. Speed and acceleration are calculated by determining when the transducer passes the receiver of the controller. Since the range of the transducer is very limited, the transducer will only respond to an interrogation signal when the transducer is next to the controller receiver. The transducer has a tire pressure fill valve.

Abstract: A system for detecting the air pressure in each wheel and for effecting inflation or deflation in each wheel while the vehicle is operating including a controller (30) and a high pressure reservoir (34) mounted on each wheel. Each controller includes a magnet (45) that is positioned responsive to the pressure in the associated tire and a stationarily mounted solenoid detector (32) senses the position of the magnet and generates a signal which is fed to a data processor (97) for the generation of an output signal to the vehicle operator indicating the pressure in the tire. Additionally, through actuation of the control, a current is passed through a coil (62) on the solenoid detector to actuate the magnet (45) in an individual wheel for opening a valve and allowing air to flow through the tube (39) into the tire for raising the tire pressure, or to allow the exhaust of air to lower the tire pressure.