Electric expansion valve control for a refrigeration system

Abstract

A refrigeration system including a condenser having a condenser inlet and a condenser outlet, a compressor fluidly connected to the condenser inlet, and an evaporator including an evaporator inlet and an evaporator outlet. The evaporator outlet is fluidly connected to the compressor. A compressor speed sensor senses an operational speed of the compressor. An electric expansion valve (EEV) is fluidly connected to the condenser outlet and the evaporator inlet. The EEV includes a valve member that is selectively positioned to establish a desired opening to pass refrigerant from the condenser to the evaporator. A controller is electrically connected to the EEV and the compressor speed sensor. The controller establishes the desired opening of the valve member based on one of a cooling mode superheat value and a heating mode super heat value, and the operational speed of the compressor.

What is claimed is: 
     
         1 . A refrigeration system comprising:
 a condenser including a condenser inlet and a condenser outlet;   a compressor fluidly connected to the condenser inlet;   an evaporator including an evaporator inlet and an evaporator outlet, the evaporator outlet being fluidly connected to the compressor;   a compressor speed sensor that senses an operational speed of the compressor;   an electric expansion valve (EEV) fluidly connected to the condenser outlet and the evaporator inlet the EEV including a valve member that is selectively positioned to establish a desired opening to pass refrigerant from the condenser to the evaporator; and   a controller electrically connected to the EEV and the compressor speed sensor, the controller establishing the desired opening of the valve member based on one of a cooling mode superheat value and a heating mode super heat value, and the operational speed of the compressor.   
     
     
         2 . The refrigeration system according to  claim 1 , further comprising:
 a first sensor that detects a temperature of refrigerant passing into the compressor;   a second sensor that detects a temperate of refrigerant passing through the evaporator; and   a third sensor that detects a temperature of refrigerant passing through the condenser, wherein the cooling mode superheat value comprises a difference between temperatures sensed and the first and second sensors, and the heating mode superheat values comprises a difference between the first and third sensors.   
     
     
         3 . A method of controlling refrigerant flow in a refrigeration system, the method comprising:
 sensing a temperature of refrigerant entering a compressor of the refrigeration system;   detecting a temperature of refrigerant at an evaporator of the refrigeration system;   sensing a temperature of refrigerant at a condenser of the refrigeration system;   calculating one of a cooling mode superheat value and a heating mode superheat value;   determining an operational speed of the compressor; and   establishing a degree of opening of an electric expansion valve (EEV) based on the one of the cooling mode superheat value and the heating mode superheat value, and the operational speed of the compressor.   
     
     
         4 . The method of  claim 3 , wherein establishing the degree of opening of the EEV includes establishing the degree of opening based in the one of the cooling mode superheat value and the heating mode superheat value, and adjusting the degree of opening based on the operational speed of the compressor.