Temperature control method and apparatus
AssigneeNational Forge Company
InventorsDonald E. Witkin, Arnold G. Bowles
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Abstract
The disclosed invention describes an apparatus and method for bringing a system having high interactive portions to a predetermined temperature distribution. The invention includes a difference controller which provides, through two separate drivers, a fixed total amount of energy to the system being controlled. If the system being controlled also has a long cycle time, second and third temperature controllers may be used to bring the system to the equilibrium temperature with a minimum amount of overshoot. The invention is particularly advantageous when used in connection with a high pressure, high temperature vessel useful in growing quartz crystals.
Claims7
A method for controlling the temperature difference between two locations is an interactive system comprising the steps of
- sensing a first temperature at the first location,
- sensing a second temperature at the second location,
- applying fist and second output energy in response to the difference between the first and second sensed temperatures to first and second heater elements associated with the first and second locations respectively;
- and
- maintaining the total energy applied to said first and second heater elements substantially constant.
A method for bringing a system from which heat is lost and having a long thermal lag time to an equilibrium temperature comprising the steps of
- sensing the temperature of said system,
- applying a first output energy in response to said sensed temperature to a first heater element, said output energy when the temperature of the system is near the equilibrium temperature being significantly smaller than the available output energy,
- applying a second output energy to a second heater element in response to said sensed temperature, and
- reducing the second output energy when said temperature exceeds a predetermined value.
Dependencies are inferred from the claim text.