Thermostatic expansion valve with electronic controller

Claim 1

A refrigerant control system comprising: (a) pump means including condenser means providing a source of pressurized liquid refrigerant; (b) expansion valve means with a body having an inlet and outlet including conduit means operative to communicate pressurized liquid refrigerant from said pump means to the inlet thereof and having a valve member disposed in said body and movable therein for controlling flow of said liquid to said outlet for expansion; (c) blower means operative for circulating air over said condenser means; (d) evaporator means having an inlet and outlet and connected for receiving refrigerant flow at the inlet thereof from the outlet of said valve means and operative to absorb heat from a compartment to be refrigerated and effect vaporization of said refrigerant for discharge at the outlet thereof; (e) said valve means body including a continuous passage therethrough connected to receive refrigerant flow from said evaporator means outlet and discharge refrigerant flow to the inlet of said pump means; (f) said valve means further including actuator means responsive to the temperature of the refrigerant in said continuous passage operable for moving said valve member; (g) first thermistor means disposed in said inlet of said valve means body and including current limiting resistance means electrically in series with said thermistor means; (h) first circuit means operative to provide a flow of current to said thermistor means sufficient to cause boiling of refrigerant coming into contact therewith including means operative to determine the temperature of said flow at said boiling; (i) (h) second circuit means operative to compare said temperature with saturation values in a look-up table and convert said temperature to saturation pressure, said second circuit means operative to cycle said blower means responsive to said pressure; (j) second thermistor means disposed at the outlet of said evaporator for sensing the temperature of the flow of refrigerant thereof; and (k) second circuit means receiving a signal from said second thermistor means and operative to energize said pump means when said sensed temperature is greater than a predetermined "ON" temperature and operative to deenergize said pump means when said sensed temperature is less than a predetermined "OFF" temperature.