초록 ▼

Sensor and reference wires are directly exposed to the airflow past a vehicle. The wires are electrically conductive, and each has a resistance varying with its temperature. A continuous fixed voltage is passed through the reference wire. A short pulse of greater constant voltage is passed through t

Sensor and reference wires are directly exposed to the airflow past a vehicle. The wires are electrically conductive, and each has a resistance varying with its temperature. A continuous fixed voltage is passed through the reference wire. A short pulse of greater constant voltage is passed through the sensor wire, the voltage of sufficient magnitude to cause the rapid heating of the sensor wire during the pulse. The resultant rate of heat of the sensor wire, and its final temperature at the end of the pulse, is determined by whether ice or water is on the sensor wire. Circuitry is provided to generate an ice present signal when the difference in current flow during the pulse through the sensor wire and through the reference wire is of such magnitude and sign as to indicate that ice was in contact with the sensor wire. Due to water\s heat of fusion, the effect of ice on the sensor wire is readily distinguished from the effect of water. In one embodiment a probe assembly is provided which includes a probe tube extending at an angle to the direction of movement of the vehicle. The sensor and reference wires are positioned in separate thread grooves for protection and wound repeatedly around a portion of the probe tube. A heater is fitted in a hollow cavity of the probe tube to facilitate melting of ice which forms on the sensor wire.

대표청구항 ▼

An ice detection apparatus for determining whether weather conditions are ice forming, comprising: pulse voltage means for supplying a pulse of fixed first voltage when enabled; sensor means, directly exposed to said weather conditions and electrically connected to said pulse voltage means, for pres

An ice detection apparatus for determining whether weather conditions are ice forming, comprising: pulse voltage means for supplying a pulse of fixed first voltage when enabled; sensor means, directly exposed to said weather conditions and electrically connected to said pulse voltage means, for presenting an electrical resistance in accordance with the temperature of said sensor means; continuous voltage means for supplying a continuous fixed second voltage; reference means, exposed to the ambient temperature to which said sensor means is exposed and electrically connected to said continuous voltage means, for presenting an electrical resistance indicative of said ambient temperature; comparator means, electrically connected to said sensor means and said reference means, for generating an ice-present signal when the resistance of said sensor means during said pulse, when compared to the resistance of said reference means, indicates that ice was in contact with said sensor means during said pulse; heater means, thermally coupled to said sensor means and reference means, for heating said sensor means and reference means when enabled, to melt ice in contact with said sensor means and reference means; ambient temperature detection means, electrically connected to said reference means, for generating a start detection signal when the resistance of said reference means indicates said ambient temperature is sufficiently low to allow water to freeze; high temperature detection means, electrically connected to said reference means, for generating a reset signal when said heater means is enabled and the resistance of said reference means indicates that said heater means has heated said reference means and sensor means to a temperature sufficiently high so as to melt ice in contact with said sensor means; and control means, receiving said reset signal and said start detection signal, for repetitious spaced enabling of said pulse voltage means while receiving said start detection signal, and for enabling said heater means upon receiving said ice-present signal until receiving said reset signal.