MODULATED TEMPERATURE CONTROL FOR ENVIRONMENTAL CHAMBER

A temperature-controlled environmental chamber includes a resistance heater controlled by a solid state relay and a refrigeration unit including an electronically controlled suction throttling valve connected in the refrigerant line between the evaporator and the inlet of the compressor. A temperatu...

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Bibliographische Detailangaben
Hauptverfasser:	DRINKWINE, DUANE C, BENEVELLI, JOHN A, MURRAY, MICHAEL L
Format:	Patent
Sprache:	eng ; fre
Schlagworte:	AIR-CONDITIONING, AIR-HUMIDIFICATION, VENTILATION, USE OF AIRCURRENTS FOR SCREENING ARRANGEMENTS OR ADAPTATIONS OF HEATING, COOLING, VENTILATING,OR OTHER AIR-TREATING DEVICES SPECIALLY FOR PASSENGER OR GOODSSPACES OF VEHICLES BLASTING COMBINED HEATING AND REFRIGERATION SYSTEMS CONTROLLING HEAT PUMP SYSTEMS HEATING LIGHTING LIQUEFACTION SOLIDIFICATION OF GASES MANUFACTURE OR STORAGE OF ICE MECHANICAL ENGINEERING PERFORMING OPERATIONS PHYSICS RANGES REFRIGERATION MACHINES, PLANTS OR SYSTEMS REFRIGERATION OR COOLING REGULATING SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES TRANSPORTING VEHICLES IN GENERAL VENTILATING WEAPONS
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Beschreibung
Zusammenfassung:	A temperature-controlled environmental chamber includes a resistance heater controlled by a solid state relay and a refrigeration unit including an electronically controlled suction throttling valve connected in the refrigerant line between the evaporator and the inlet of the compressor. A temperature controller senses the temperature in the chamber and compares it to a set point temperature and outputs a pulse-width modulated control signal indicative of the difference between the two temperatures. The control signal directly controls the heater relay for substantially continuous variation between minimum and maximum heating conditions. The control signal is converted to an analog signal for controlling the throttling valve of the refrigeration unit for substantially continuous variation between maximum and minimum cooling conditions, so that the amount of cooling provided is inversely proportional to the amount of heating provided. A hot gas bypass is provided for maintaining a minimum input pressure on the condenser and a refrigerant bypass is provided to maintain the input temperature of the compressor below a predetermined maximum.