Tire pressure sensor for motor vehicles

Claim 1

A tire pressure sensor for a vehicle, said vehicle having a plurality of vehicle wheels, each of said vehicle wheels having a wheel axis and a wheel rim on which a tire is mounted, said tire having a tire pressure and a running surface said tire pressure sensor comprising a pressure switch which is mounted on the circumference of the wheel rim of one of the vehicle wheels and which extends radially relative to the wheel axis, said pressure switch being actuable by the tire pressure and being provided with an electrically conductive diaphragm responding to and communicating with the tire pressure in the tire, said electrically conductive diaphragm being arranged parallel to the running surface of the tire, said diaphragm being provided with an added mass for increasing a switching threshold of the tire pressure sensor as a function of speed of the vehicle, said diaphragm having a contact, which is contacted by a contact surface, on a central area of the diaphragm for closing an electric circuit, when the tire pressure in the tire is large enough, wherein the state of the electric circuit is to be monitored without the use of wires by a signal generator, which is mounted in the vehicle and said signal generator includes an evaluating circuit; furthermore the added mass (30, 30a) is fastened at the diaphragm center, is free so as not to impede the motion of the diaphragm and is determined by a functional relationship between the variables Δp, r 2 , R and v 2 so as to be large enough to increase the switching threshold by a desired pressure differential Δp compared with the threshold value p o at a stationary state, at a predetermined radius r of the diaphragm, at a predetermined rotational radius R of the diaphragm, and at a predetermined rotational speed v of the diaphragm.