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Tire air pressure system

  • US 5,491,465 A
  • Filed: 11/14/1994
  • Issued: 02/13/1996
  • Est. Priority Date: 11/14/1994
  • Status: Expired due to Fees
First Claim
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1. An improved inflatable tire air pressure monitoring system of the type havinga valve stem having a valve core plunger, said valve stem attached to said tire;

  • a hub;

    a wheel having a valve stem hole, said tire mounted on said wheel so that said valve stem is disposed through said valve stem hole, and said wheel mounted on said hub;

    an electrical contact brush;

    means for attaching said brush proximate to said hub;

    an annunciator having a first terminal and a second terminal;

    an external direct current voltage source;

    means for electrically connecting said first terminal to the positive terminal said voltage source;

    means for electrically connecting said wheel to the negative terminal said voltage source; and

    means for electrically connecting said second terminal to said brush;

    wherein the improvement comprises;

    an electrically insulating annular disk having a planar first surface and a wire lead hole, said disk demountably and concentrically interposed between said wheel and said hub so that said first surface is proximate to said hub, and said wire lead hole disposed through said disk;

    a electrically conductive flattened ring attached to said first surface concentric with said disk, proximate to said wire lead hole, and disposed in sliding contact with said brush;

    an electrically conducting sensor housing having a cylindrical cavity, a stepped-bore aperture, a bushing hole, and a plurality of air passages, said aperture having a threaded valve stem bore and a threaded adjustment screw bore, said aperture disposed through said sensor housing so that said aperture is coaxial with said cylindrical cavity, said adjustment screw bore is adjacent to said cylindrical cavity, said bushing hole disposed through said sensor housing, coaxial with and adjacent to said cylindrical cavity opposing said adjustment screw bore, said valve stem bore threadably engaged with said valve stem, said air passages disposed through said sensor housing and proximate to said valve stem bore so that air may flow from said valve stem into said cylindrical cavity;

    an electrically conducting adjustment screw having a screw first end and a screw second end, said adjustment screw disposed in said adjustment screw bore, the length of said adjustment screw chosen so that said screw first end projects into said valve stem bore, contacts and depresses said valve core plunger and said screw second end projects into said cylindrical cavity;

    an electrically insulating bushing disposed within said bushing hole so that the axis of said bushing is coaxial with the axis of said cylindrical cavity;

    an electrically conducting piston head having a circumferential slot, said piston head disposed coaxially with respect to and within said cylindrical cavity, the diameter of said piston head chosen to be slightly less than the diameter of said cylindrical cavity;

    an electrically conducting piston shaft having a piston shaft first end and a piston shaft second end, said piston shaft first end attached to said piston head so that said piston shaft is normal to and coaxial with said piston head and said piston shaft second end is slidably disposed through said bushing;

    an electrically insulating, flexible, resilient O-ring, disposed surrounding said piston head in said circumferential slot, the thickness of said O-ring chosen so that said O-ring forms an airtight seal with respect to said cylindrical cavity while permitting sliding coaxial movement of said piston head with respect to said cylindrical cavity;

    means for biasing said piston head away from said bushing so that said piston head is electrically insulated from said sensor housing;

    means for electrically connecting said piston shaft second end to said ring; and

    means for electrically connecting said sensor housing to said wheel.

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