INFLATION PRESSURE MONITOR FOR VEHICLE TYRES

PCT No. PCT/DE89/00624 Sec. 371 Date May 6, 1991 Sec. 102(e) Date May 6, 1991 PCT Filed Oct. 3, 1989 PCT Pub. No. WO90/08663 PCT Pub. Date Aug. 9, 1990.A tire-pressure monitor (13) comprising a pressure switch to be fixed to the periphery of the wheel rim (12) of vehicle wheels radially to the wheel axis is proposed, which pressure switch consists of a reference-pressure chamber (20) which is closed off towards the tire by an electrically conductive diaphragm (21). To close an electric circuit the diaphragm (21), when tire pressure is sufficient, is pressed onto a contact pin (22) inserted in an insulated manner into the reference-pressure chamber (20). To achieve an increase in the switching threshold as a function of speed, which increase can be determined in a defined manner, the diaphragm (21), free towards the tire, is provided with an elastic additional mass (30) which is applied over the surface to one diaphragm side and whose modulus of elasticity, in relation to that of the diaphragm (21) is less than one tenth.