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Device and process for controlling air pressure in tires

  • US 4,953,394 A
  • Filed: 10/07/1988
  • Issued: 09/04/1990
  • Est. Priority Date: 10/08/1987
  • Status: Expired due to Fees
First Claim
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1. Apparatus for monitoring the air pressure in a pneumatic tire carried by the rim of a vehicle wheel which comprises:

  • a pneumatic tire having a tire air space;

    a vehicle wheel having a rim carrying said tire along an axis;

    a sensing element arranged at the rim which can be deformed and acted upon by tire pressure;

    a permanent magnet as a measurement value generator connected to the sensing element;

    a measurement value sensor in operative relationship to the permanent magnet arranged in the region of rotary movement of the wheel and fixed to the vehicle in a stationary position;

    an evaluation circuit connected to the measurement value sensor;

    wherein the sensing element is in the form of a bellows mounted with a substantially axis-parallel direction of movement; and

    wherein the permanent magnet which is connected to the sensing element is displaceable in axis-parallel relationship at the outside of the tire in dependence on the tire pressure, wherein at normal tire pressure the permanent magnet remains in a position close to the measurement value sensor with a greater spacing therebetween at reduced tire pressure, said apparatus including an attachment housing on the rim with said bellows projecting from said attachment housing into the tire air space, a bistable rocker member for moving said permanent magnet and an axial rod connecting said bellows with said rocker member, wherein said permanent magnet is mounted in axis-parallel relationship.

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