Arrangement with a switch, mounted on the wheel of a motor vehicle, for monitoring the internal pressure of a tyre

摘要

The invention relates to an arrangement for monitoring a status variable in the interior of the wheel of a motor vehicle, which variable is emitted by one of the positions of a switch mounted there as long as the said position is within a desired range. When the position leaves this range, the switch assumes the other position which is inductively interrogated once per revolution of the wheel by a pulse transmitter mounted on the chassis by an oscillatory circuit mounted on the wheel being excited to produce damped oscillations whose degree of damping is determined by the switch position. This degree of damping is tapped off at least once in a fixed time interval after excitation at the damped oscillation received by the circuit of the chassis and is tested in an evaluation device, the position of the switch in the interior of the tyre being determined as a function of the size of the said damping and, if appropriate, a warning device for the driver being activated. The entire arrangement operates in the kilohertz range and can thus be easily realised by commercially available circuitry components. <IMAGE>