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Tire-pressure monitor for vehicles

  • US 5,134,880 A
  • Filed: 05/06/1991
  • Issued: 08/04/1992
  • Est. Priority Date: 01/30/1989
  • Status: Expired due to Fees
First Claim
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1. Tire-pressure monitor for vehicles, comprising a pressure switch which is to be fixed to the periphery of the wheel rim of vehicle wheels radially to the wheel axis, is to be actuated by the tire pressure and has a reference-pressure chamber which is closed off towards the tire by an electrically conductive diaphragm which is arranged parallel to the tread of the tire and carries an additional mass provided for increasing the switching threshold as a function of speed, and a contact which is inserted in an electrically insulated manner into the reference-pressure chamber and against which, when air pressure in the tire is sufficient, a contact area at the centre region of the diaphragm bears for closing an electric circuit, in which arrangement the state of the electric circuit is to be monitored in a cordless manner by a receiver fixed to the vehicle and having an analysing circuit, characterized in that the diaphragm (21) is free towards the tire (11) and the additional mass (30, 30a, 30b) is applied over the surface to at least one diaphragm side and is also made of a material whose modulus of elasticity is less than 1/10th of the modulus of elasticity of the diaphragm (21).

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