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Vehicle tire pressure sensing device

  • US 3,938,076 A
  • Filed: 03/05/1974
  • Issued: 02/10/1976
  • Est. Priority Date: 03/06/1973
  • Status: Expired due to Term
First Claim
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1. A tire pressure sensing device adapted to sense a fall in the pressure in a tire below a predetermined value, comprising a casing disposed in a pressure chamber of said tire and fixedly mounted on a wheel rim cooperating with said tire, a flexible diaphragm dividing said casing into an atmospheric chamber vented to the atmosphere and a pressure chamber communicating with said pressure chamber of said tire, said diaphragm being deformable in response to the pressures in said pressure chamber of said casing, a stationary contact disposed in said pressure chamber of said casing, a leaf spring disposed in said pressure chamber of said casing and supported by said casing, said leaf spring being deformable in response to movements of said diaphragm, a movable contact fixedly mounted on said leaf spring and engageable with said stationary contact, in which said casing has formed on one end thereof a projection extending outwardly of said pressure chamber of said tire through said rim and is fixedly mounted on said rim through said projection, said projection having a passage for communicating said atmospheric chamber with the atmosphere, in which said leaf spring comprises a flat section rockably supported by said casing and a curved section connected at one end thereof to said flat section and supported at the other end thereof by said casing, said curved section engaging said diaphragm through a bracket, said movable contact being mounted on said flat section, in which said flat section of said leaf spring comprises two members made of materials having different coefficients of thermal expansion.

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