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DEVICE FOR AUTOMATICALLY DETECTING ABNORMAL CONDITIONS IN VEHICLE TIRES

  • US 3,852,717 A
  • Filed: 11/01/1972
  • Issued: 12/03/1974
  • Est. Priority Date: 11/22/1971
  • Status: Expired due to Term
First Claim
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1. In a device for automatically detecting the loss of pressure and the abnormal increase of temperature within a pneumatic tire of wheeled vehicle, having a normally closed pressure switch to be opened when pressure in the tire is below a predetermined pressure value;

  • a normally closed temperature switch to be opened when temperature of the tire is above a predetermined temperature value;

    coupling means comprising a primary coil and a secondary coil, the secondary coil being secured concentrically on an axle of the vehicle for rotation therewith and being electrically connnected in series with said pressure switch and said temperature switch, the primary coil being secured rigidly with respect to the frame of the vehicle and concentrically with respect to the secondary coil so that the primary coil exhibits an inductance change upon open of said switches; and

    warning means;

    a clock pulse generator to produce clock pulses;

    a first flip-flop connected to said clock pulse generator for providing, as its output, frequency division of said clock pulses;

    a second flip-flop connected to said first flip-flop for providing, as its output, further frequency division of said clock pulses;

    resistor electrically connecting said second flip-flop to said primary coil of said coupling means;

    comparator gate means responsive to a voltage at a junction point between said resistor and said primary coil of said coupling means for providing a pulse output when said voltage is above a reference voltage;

    AND logical function gate means connected to said first flipflop and to said comparator gate means to receive outputs thereof, respectively, said AND logical function gate means being operable to provide a pulse output responsive to coincidence of inputs thereto; and

    means responsive to said output pulse of said AND logical function gate means for energizing said warning means.

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