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US 4,356,961 AGranted
Dual deadband control system
AssigneeHoneywell Inc.
InventorGary A. Smith
Life of this patent
Estimating the term…
Abstract
A temperature control system utilizing a plurality of heating or cooling devices to maintain the temperature at a desired level, minimizing rapid multi-stage cycling by using dual deadband zones.
Claims21
In a condition control system including a plurality of condition control devices each operable from a first state to a second state to change the condition at a predetermined location, so as to maintain the condition proximate a predetermined value, the improvement comprising:
- condition responsive means including a condition sensor positioned at the predetermined location and the condition responsive means operable to produce a first signal which varies with changes of condition sensed by the condition sensor;
- control means connected to the condition responsive means to receive the first signal and operable to produce a control signal, the control signal having a first characteristic when the condition sensed by the condition sensor is greater than a first predetermined amount above the predetermined value, having a second characteristic when the condition sensed by the condition sensor is greater than a second predetermined amount above the predetermined value, having a third characteristic when the condition sensed by the condition sensor is less than a third predetermined amount below the predetermined value and having a fourth characteristic when the condition sensed by the condition sensor is less than a fourth predetermined amount below the predetermined value;
- and
- means for connecting the control means to the plurality of condition control devices to present the control signal thereto, a first of the condition control devices being turned from the first state to the second state upon receipt of a control signal of the first characteristic and being turned from the second state to the first state by a control signal of the third characteristic only when no other of the condition control devices is in the second state, a second of the condition control devices being turned from the first state to the second state upon receipt of a control signal of the second characteristic only when the first condition control device is in the second state, and the second of the condition control devices thereafter being turned from the first state to the second state and from the second state to the first state upon receipt of output signals of the third characteristic and first characteristic respectively so long as the first of the condition control devices remains in the second state.
1 more element
Apparatus for use with first and second condition control devices each operable upon receipt of a signal to change from a first state to a second state so as to change the value of the condition and a sensing device having an output indicative of the value of the condition comprising:
- means for connection to the sensing device to receive the output and operable to produce a condition signal of magnitude which varies with variations in the condition;
- means establishing first and second reference values indicative of the range in which the condition signal will be allowed to vary in order that the condition be maintained proximate a desired value;
- means establishing third and fourth reference values above and below the first and second reference values respectively;
- comparing means comparing the condition signal with the first, second, third and fourth reference values to produce a first output signal when the condition signal is greater than the first reference value, a second output signal when the condition signal is less than the second reference value, a third output signal when the condition signal is greater than the third reference value and a fourth output signal when the condition signal is less than the fourth reference value;
- and
- means for connecting the comparing means to the first and second condition control devices so that as long as the second condition control device is in the first state, the first condition control device will be changed from the first to the second state upon receipt of the first output signal and changed from the second state to the first state upon receipt of the second output signal, and so long as the first condition control device is in the second state, the second condition control device will be changed from the first state to the second state upon receipt of the second control signal, thereafter the second condition control device will be changed from the second state to the first state upon receipt of the second output signal and changed from the first state to the second state upon receipt of the first output signal.
3 more elements
Dependencies are inferred from the claim text.