Tyre pressure sensor for motor vehicles

摘要

A tyre pressure sensor (10) for motor vehicles is proposed which is to be attached to the circumference of a wheel rim and has a switching element which is to be acted on by the air pressure in the tyre and is arranged in a reference pressure chamber (11). In order to be able to monitor a plurality of threshold values of the tyre pressure by means of a tyre pressure sensor which is cost-effective to manufacture, it is proposed to close off the reference pressure chamber (11) with respect to the tyre pressure by means of a diaphragm which consists of a ceramic film (13) and bears on its inside a plurality of contact faces (17, 18) which are arranged offset from the outer edge with different spacing and are each connected via a conductor track (19, 20) to an oscillating circuit (21). They interact with appropriately arranged countercontact faces (22, 23) which are arranged in the state of rest a short distance apart on the face of the reference pressure chamber (11) lying opposite the contact faces and are also connected to the oscillating circuit (21). Using this tyre pressure sensor, the tyre pressure can be monitored within a desired bandwidth by the different threshold values of the tyre pressure sensor (10) and the functional reliability of the tyre pressure sensor can be tested (Figure 1). <IMAGE>