Test element, mounted on the wheel of a motor vehicle, for monitoring the interior pressure of a tyre

摘要

The invention relates to the monitoring of the air pressure inside the tyre of a motor vehicle which must not drop below a predetermined threshold value; otherwise, undesired flexing occurs in the tyre which is associated with internal material abrasion and an increase in the temperature of the tyre even up to unacceptably high values. For such monitoring, a test element which responds in the microwave range and consists of a dipole and one or two chips which contain a pressure switch and a diode for halfwave rectification are mounted on the rim inside the tyre. When the test element receives radiation with the possibly pulse-coded fundamental frequency, the dipole can be excited to transmit back the first harmonic which is evaluated in the receiver. <IMAGE>