DEVICE FOR DETECTING TYRE PRESSURE

摘要

A device for detecting a tire pressure drop below a controlled value during drive of a vehicle comprises a magnetic member fixed to and rotating with the wheel rim and a switch element fixed to the wheel axle and responsive to an operative orientation of the magnetic field produced by the magnetic member which is carried by a pivotal shaft. A plunger responsive to the tire pressure drop locks the shaft and thereby the magnetic member in an inoperative position as long as the tire pressure is sufficiently high but releases the shaft as soon as the tire pressure drops, whereupon a spring turns the shaft with the magnetic member into the operative position in which the fixed switch element is actuated by the magnetic field at each turn of the wheel. The plunger is mounted in a guide sleeve extending tangentially to the wheel rim and the considerable frictional resistance due to centrifugal forces and impeding a correct operation of the plunger and of its biasing spring is eliminated by providing a low friction guiding surface.