Patent ID: 6828905
Filing Date: 2004-12-07
Classification: B60C,G08C

Abstract:
System for monitoring and signalling by radio a pressure or a change in pressure in pneumatic tyres of wheels (1) on vehicles (2), consisting of a receiver unit (9) provided in or on the vehicle (1) to which at least one antenna (6, 7), is associated, and of a electronic unit (3), arranged in the pneumatic tyre, for measuring, evaluating and transmitting tyre pressure signals, hereinafter referred to as â€œwheel-mounted electronic unitâ€ , comprisinga battery (24) as current source, a pressure sensor for picking up the pressure prevailing in the pneumatic tyre, an evaluation circuit for evaluating the measured pressure signals supplied by the pressure sensor, and a transmitter (21) which is controlled by the evaluation circuit and which transmits to the receiver unit (9) signals that contain information regarding the pressure in the tyre and/or the condition of the wheel-mounted electronic unit (3), the wheel-mounted electronic unit (3) being activated at time intervals (t0) for a period of time (T1) shorter than the time intervals (t0) and remaining otherwise in a current-saving state, characterised in that an interrogator (14) is provided on the vehicle (1) and that there is associated to the wheel-mounted electronic unit (3) on the same wheel (1) a receiver (4) which is responsive to interrogation signals sent out by the interrogator (14) and which draws the energy required for its function not from the battery (24) but from the interrogation signals as such,and that the receiver (4) has a trigger circuit (25) the output of which is connected to a trigger input of the wheel-mounted electronic unit (3) so that the latter is activated by triggering and returns to its current-saving state at the end of the before-mentioned period of time (T1).