Patent ID: 7337625

Claim:
A control system for providing controlled expansion of a liquid refrigerant from a source, under command of a controller to maintain a heat exchanger/evaporator at a selected temperature level, and comprising: a first expansion valve comprising a solenoid actuated valve having a fixed orifice size and operated by the controller at a selected duty cycle rate; a second expansion valve coupled in series with the first expansion valve and having a variable orifice size responsive to control signals from the controller, and a temperature responsive sensor coupled to the second expansion valve, the sensor including a closed bulb positioned to be responsive to the temperature of the heat exchanger/evaporator and including a coupling feeding back a corrective pressure to the second expansion valve, whereby the first expansion valve enables meeting maximum flow demands and the second expansion valve militates against the flow of liquid into the heat exchanger/evaporator portion of the refrigeration loop.