Modulated temperature control for environmental chamber
First Claim
1. Apparatus for controlling the air temperature of a served space which is equipped with a heat source and a cold source, said apparatus comprising:
- temperature sensing means for sensing the temperature in the served space, comparator means for comparing the sensed temperature to a predetermined set point temperature and generating a control signal indicative of the difference between the two temperatures, and control means coupled to said comparator means and to the heat source and the cold source and responsive to only said control signal for controlling the operation of the heat source and the cold source in a push-pull manner such that the amount of cooling provided is inversely proportional to the amount of heating provided.
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Accused Products
Abstract
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.
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Citations
20 Claims
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1. Apparatus for controlling the air temperature of a served space which is equipped with a heat source and a cold source, said apparatus comprising:
- temperature sensing means for sensing the temperature in the served space, comparator means for comparing the sensed temperature to a predetermined set point temperature and generating a control signal indicative of the difference between the two temperatures, and control means coupled to said comparator means and to the heat source and the cold source and responsive to only said control signal for controlling the operation of the heat source and the cold source in a push-pull manner such that the amount of cooling provided is inversely proportional to the amount of heating provided.
- View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. Apparatus for controlling the air temperature of a served space which is equipped with a heat source and a cold source, said apparatus comprising:
- temperature sensing means for sensing the temperature in the served space, comparator means for comparing the sensed temperature to a predetermined set point temperature and generating a control signal indicative of the difference between the two temperatures, heating control means coupled to said comparator means and to the heat source and responsive to only said control signal for controlling the operation of the heat source in a continuous manner between minimum and maximum heating conditions, refrigeration control means coupled to said comparator means and to the cold source and responsive to only said control signal for controlling the operation of the cold source in a continuous manner between maximum and cooling conditions, whereby when said control signal causes an increase in either heating or cooling it causes a corresponding decrease in the other.
- View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method for controlling the air temperature of a served space which is equipped with a heat source and a cold source, said method comprising the steps of:
- sensing the temperature in the served space, comparing the sensed temperature to a predetermined set point temperature, and controlling the output of the heat source and the cold source in accordance with only the amount and direction of separation between the sensed and set point temperatures in a push-pull manner such that the amount of the cooling provided is inversely proportional to the amount of heating provided.
- View Dependent Claims (16, 17, 18, 19, 20)
Specification