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Tire pressure variation detector

  • US 4,071,724 A
  • Filed: 04/20/1976
  • Issued: 01/31/1978
  • Est. Priority Date: 04/21/1975
  • Status: Expired due to Term
First Claim
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1. A tire pressure variation detector connected to an information-transmitting electrical circuit by on-off elements, said detector comprising a body adapted to be fastened in an opening of a wall of an airtight wheel rim for a pneumatic tire having two beads and an inside wall and containing an inner tube having an outside wall, said wall of the wheel rim extending between the two beads of the tire, said body comprising a portion intended to enter into contact with the inner tube and having a stiff elastic element bearing a movable electrical contact intended to enter into contact with a stationary electrical contact borne by another portion of said body, the two electrical contacts being electrically insulated from each other and constituting said on-off elements of said information-transmitting electrical circuit, the stiffness of the elastic element being such that the two electrical contacts touch each other when the inner tube is inflated to normal inflation air pressure and move away from each other when air pressure increases in a space outside the inner tube, said space outside the inner tube being formed by the inside wall of the tire, the outside wall of the inner tube and said wall of the wheel rim, the detector being characterized by the fact that the body is fastened in airtight manner in the opening of the wall of the wheel rim and comprises, in the portion thereof intended to enter into contact with the inner tube, a cavity which contains the stationary electrical contact and which is closed by a flexible airtight diaphragm which serves as the elastic element, said cavity being connected to said space outside the inner tube by a channel provided in the body of the detector.

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