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Early ice-warning device

  • US 4,222,044 A
  • Filed: 04/27/1978
  • Issued: 09/09/1980
  • Est. Priority Date: 05/04/1977
  • Status: Expired due to Term
First Claim
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1. A device for producing an early warning signal in anticipation of ice-formation on a road surface, of the type having ambient temperature sensing means, a first sensor unit comprising surface temperature sensing means and a first moisture detector, a second sensor unit comprising a second moisture detector and means for heating said second moisture detector, a group of comparators respectively connected to said first and second moisture detectors, first signal means for generating said early warning signal, second signal means for generating a signal when said road surface is wet, third signal means for generating a signal when ice has formed on said road surface, and means for actuating and deactuating said means for heating, wherein the improvement comprises:

  • a third sensor unit comprising a third moisture detector, means for determining the temperature of said third moisture detector, and alternate heating and cooling means;

    control means connected to said surface temperature sensing means, to said means for determining the temperature of said third moisture detector, and to the output of said second signal means, said control means being responsive to the difference between the temperature of said road surface and the temperature of said third moisture detector, and responsive to the output of said second signal means to provide electrical power to said alternate heating and cooling means when the road surface is wet;

    changeover means responsive to the temperature measured by said means for determining the temperature of said third moisture detector and to values measured by said first, second, and third moisture detectors for changing over the mode of operation of said alternate heating and cooling means to maintain a predetermined temperature difference between the temperature of the road surface and the temperature of said third moisture detector; and

    a first additional comparator connected to said third moisture detector and a second additional comparator connected to said means for determining the temperature of said third moisture detector, the inputs of said changeover means being connected to the outputs of said group of comparators and of said first and second additional comparators.

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