Patent ID: 6769264
Filing Date: 2004-08-03
Classification: F04C,F24F,F25B,Y02B

Abstract:
A system to control the degree of superheat of an air conditioner, comprising:a compressor controlled in a pulse width modulation manner according to duty control signals; a condenser, an electronic expansion valve and an evaporator constituting a refrigeration cycle together with said compressor; means for sensing properties to calculate the degree of superheat of said evaporator; and a control unit to regulate opening of said electronic expansion valve according to the calculated degree of superheat; wherein said property sensing means includes an entrance temperature sensor situated at the entrance of said evaporator and an exit temperature sensor situated at the exit of said evaporator, and said degree of superheat is determined by the difference between mean entrance and exit temperatures of said evaporator sensed by said entrance temperature sensor and said exit temperature sensor for a period of time corresponding to a duty cycle period of said compressor.