Melvin M Winters

US Patent:

48798797, Nov 14, 1989

Filed:

Oct 5, 1988

Appl. No.:

7/253715

Inventors:

Joseph Marsala - North Chelmsford MA
Melvin M. Winters - Berrien Springs MI

International Classification:

G05D 2330
G05D 1500

US Classification:

62202

Abstract:

Apparatus for controlling a heating or cooling system of the type that includes an evaporator and a thermostatic expansion valve having a thermostatic bulb. The control apparatus comprises a thermoelectric heat pump device responsive to an electrical control signal for controlling transfer of thermal energy to and from the thermostatic bulb, at least one temperature sensing device associated with the heating or cooling system, and an electronic control circuit. The control circuit is responsive to the sensed temperature to provide the electrical control signal to the thermoelectric device for maintaining a desired operating condition of the evaporator. The thermoelectric device acts as a gate or heat pump for controlling flow of thermal energy to and from the thermostatic bulb with a relatively small amount of electrical energy input. Preferably, the thermoelectric heat pump device is positioned between the thermostatic bulb and the suction line of the evaporator so as to control transfer of thermal energy between the suction line and the thermostatic bulb. Preferably, the control apparatus senses the temperature difference between the suction line and the inlet line of the evaporator and maintains the temperature difference within prescribed limits.