Importance

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Abstract

A pulse controlled refrigeration expansion valve for multiple evaporators and method of controlling the valve is disclosed. The refrigeration system on which this invention is typically used includes a single source of pressurized refrigerant and a plurality of evaporators. Each evaporator has an expansion valve associated therewith which is preferably an on/off (open/closed) direct controlled solenoid valve. The valve is periodically energized (opened) and de-energized (closed) in response to a parameter (e.g., superheat) of its respective evaporator such that the ratio of energization time/de-energization time during each period (e.g., 4 seconds) of operation of the valve is varied in response to the system parameter(s) and such that the on/off solenoid valve functions as a modulated refrigerant flow control expansion valve. A temperature sensor is provided which senses the temperature of the space being refrigerated by a respective evaporator (e.g., the interior of a freezer cabinet in a supermarket) so that upon the temperature of the refrigerated space controlled by the respective valve being within a predetermined temperature range, the temperature sensor will override the control for the solenoid valve thus closing the valve and stopping the flow of refrigerant through the respective evaporator while refrigerant continues to flow to other evaporators.

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First Claim