Early ice-warning device
First Claim
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.
0 Assignments
0 Petitions
Accused Products
Abstract
An early warning signal is produced when there is a danger of ice forming on a road surface by means of a device comprising a temperature sensor for determining the ambient temperature, a sensor unit for determining the temperature and moisture of the road surface, a heatable sensor unit having a heating element and a moisture-detecting gap, and comparators for comparing the voltages supplied by the temperature sensors and the moisture sensors with reference voltages, comprises in addition thereto a sensor unit having a further moisture-detection gap, one or more elements for alternately cooling or heating this further moisture-detection gap, and a temperature sensor for determining the temperature of this further moisture-detection gap, as well as signal generators generating signals in response to the output signals of the comparators for indicating whether the road surface is dry, wet, or icy. The early warning signal is reliably given in advance of actual ice-formation solely as a function of the road surface temperature and of the condition of the moisture sensors. The response thresholds of those comparators which are associated with the moisture sensors are preferably varied as a function of the road surface temperature in order to allow for the influence exerted on the freezing point by thawing agents spread on the road surface.
-
Citations
9 Claims
-
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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
Specification