Means to measure, indicate and regulate thickness of ice layer in refrigeration system

Claim 1

In a refrigeration system: a compressor; a first electric motor for driving said compressor; an evaporator for receiving refrigerant from said compressor, said evaporator having a portion which is submersible in water in a tank and is susceptible to formation of a layer of ice thereon; a compressor motor controller operable to energize and de-energize said first electric motor; and means for measuring, indicating and regulating the thickness of said layer of ice and comprising: a movable probe extendible into the water in said tank for contacting said layer of ice, said probe being reciprocably movable during one cycle of operation from a starting position, to an ice contacting position and back to said starting position; a potentiometer responsive to movement of said probe to provide a signal proportional to probe position; a second electric motor energizable to effect movement of said probe; timing means to effect energization of said second electric motor at periodic intervals of time to effect one cycle of operation of said probe for each periodic energization of said second electric motor; an indicator device operable to provide an indication of the thickness of said layer of ice; and an electrical control circuit comprising a peak hold circuit to derive a peak value signal received from said potentiometer during each cycle of operation of said probe and to maintain said peak value signal for a predetermined interval of time after said each cycle of operation; and for providing a signal to operate said indicator device and to operate said compressor motor controller for said first electric motor.