TYRE PRESSURE SENSOR FOR MOTOR VEHICLES

PCT No. PCT/DE88/00634 Sec. 371 Date Jun. 4, 1990 Sec. 102(e) Date Jun. 4, 1990 PCT Filed Oct. 16, 1988 PCT Pub. No. WO89/05239 PCT Pub. Date Jun. 15, 1989.The tire pressure sensor (13) for monitoring vehicle tires is fastened radically relative to the wheel axis at the circumference of a wheel rim and includes a reference pressure chamber (20) with a contact pin (22) which cooperates with an electrically conductive diaphragm (21) closing the reference pressure chamber (20) toward the tire. An added mass (30) is fastened freely at the diaphragm center for raising the switching threshold of the tire pressure sensor (13) as a function of speed and is dimensioned in such a way that the switching threshold is raised by a desired pressure differential ( DELTA p) relative to the switching threshold po at standstill at a predetermined radius r of the diaphragm (21), a predetermined rotational radius R of the diaphragm (21) and a predetermined rotational speed v of the diaphragm (21). The required added mass (m) results from the equation m=f( DELTA p, r2, R, v2), advantageously m=( pi /4)r2{[R/v2] DELTA p - p.a}k wherein p is the material density of the diaphragm, a is the diaphragm thickness and the factor k is between 1.1 and 1.5.