US3869597A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-regulating proportionally controlled heating apparatus and technique
Assignee: National Aeronautics and Space Administration
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Filing: 1974-02-27
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Granted: 1975-03-04
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Expires: 1994-02-27
Abstract
Abstract A self-regulating proportionally controlled heating apparatus and technique is provided wherein a single electrical resistance heating element having a temperature coefficient of resistance serves simultaneously as a heater and temperature sensor. The heating element is current-driven and the voltage drop across the heating element is monitored and a component extracted therefrom which is attributable to a change in actual temperature of the heating element from a desired reference temperature, so as to produce a resulting error signal. The error signal is utilized to control the level of the heater drive current and, thereby, the actual heater temperature in a direction to reduce the noted temperature difference. The continuous nature of the process for deriving the error signal feedback information results in true proportional control of the heating element without the necessity for current-switching which may interfere with nearby sensitive circuits, and with no cyclical variation in the controlled temperature.
Inventors
- 👤 Maxwell G Strange
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:13
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/24; G05D23/2401
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
154 words
A self-regulating controlled heating apparatus, said apparatus comprising: an a electrical resistance heating element having a temperature coefficient of resistance; current generator means coupled to said heating element for continuously current driving said heating element, said current generator means being responsive to an error signal to modify the level of the current drive; and error signal generator means coupled to said heating element, said error signal generator means monitoring the voltage drop across said heating element and deriving an error signal therefrom representative of only that component of the voltage drop attributable to a change in actual temperature of said heating element from a desired reference temperature; said error signal generator means further being connected in a feedback loop to said current generator means such that said error signal continuously effects a modification of the level of the current drive from said current generator means to return said heating element to said reference temperature.
Claim 2
Dependent Claim
154 words
A self-regulating controlled heating apparatus, said apparatus comprising: an a electrical resistance heating element having a temperature coefficient of resistance; current generator means coupled to said heating element for continuously current driving said heating element, said current generator means being responsive to an error signal to modify the level of the current drive; and error signal generator means coupled to said heating element, said error signal generator means monitoring the voltage drop across said heating element and deriving an error signal therefrom representative of only that component of the voltage drop attributable to a change in actual temperature of said heating element from a desired reference temperature; said error signal generator means further being connected in a feedback loop to said current generator means such that said error signal continuously effects a modification of the level of the current drive from said current generator means to return said heating element to said reference temperature.
Claim 3
Dependent Claim
137 words
A heating apparatus as defined in claim 1, wherein said error signal generator means comprises: difference amplifier means for generating an output voltage representative of the difference between the voltage drop across said heater element and a voltage proportional to the level of the heater element current drive; divider means for generating an output voltage representative of the quotient of a division of said output voltage of said difference amplifier means by a voltage proportional to the instantaneous level of the heater element current drive, said output voltage thereby being proportional to the actual temperature of said heater element; and means for generating an output voltage representative of the difference between said output voltage of said divider means and a voltage representative of the desired temperature of said heater element, said output voltage defining said error signal.
Claim 4
Dependent Claim
31 words
A heating apparatus as defined in claim 2, wherein said current generator means comprises voltage-to-current converter means responsive to said error signal output voltage to generate said heater element current drive.
Claim 5
Independent Claim
129 words
A method of effecting continuous and proportional self-control of the temperature of an electrical heating element having a temperature coefficient of resistance, said method comprising the steps of: continuously current-driving the resistance heater element; simultaneously monitoring the voltage drop across the resistance heater element; electrically offsetting the monitored voltage drop by an amount proportional to the heater drive current; electrically dividing the offset voltage drop by a term similarly proportional to the instantaneous heater drive current, to thereby provide a signal voltage representative of the actual heater temperature; electrically comparing the actual temperature signal voltage with a value representative of the desired heater temperature to provide a difference signal; and modifying the heater drive current in response to the difference signal in a direction to reduce said difference signal.
Claim 6
Independent Claim
129 words
A method of effecting continuous and proportional self-control of the temperature of an electrical heating element having a temperature coefficient of resistance, said method comprising the steps of: continuously current-driving the resistance heater element; simultaneously monitoring the voltage drop across the resistance heater element; electrically offsetting the monitored voltage drop by an amount proportional to the heater drive current; electrically dividing the offset voltage drop by a term similarly proportional to the instantaneous heater drive current, to thereby provide a signal voltage representative of the actual heater temperature; electrically comparing the actual temperature signal voltage with a value representative of the desired heater temperature to provide a difference signal; and modifying the heater drive current in response to the difference signal in a direction to reduce said difference signal.
Claim 7
Dependent Claim
112 words
In a heating apparatus wherein an electrical resistance heating element having a temperature coefficient of resistance is continuously driven by a current source having a variable output level, the improvement of a means for monitoring the actual temperature of the heating element, said improvement comprising; means for monitoring the voltage drop across the resistance heater element while the heater element is being currentdriven; means for electrically offsetting the monitored voltage drop by an amount proportional to the heater drive current; and means for electrically dividing the offset voltage drop by a term similarly proportional to the instantaneous heater drive current, to thereby provide a signal voltage representative of the actual heater temperature.
Claim 8
Dependent Claim
112 words
In a heating apparatus wherein an electrical resistance heating element having a temperature coefficient of resistance is continuously driven by a current source having a variable output level, the improvement of a means for monitoring the actual temperature of the heating element, said improvement comprising; means for monitoring the voltage drop across the resistance heater element while the heater element is being currentdriven; means for electrically offsetting the monitored voltage drop by an amount proportional to the heater drive current; and means for electrically dividing the offset voltage drop by a term similarly proportional to the instantaneous heater drive current, to thereby provide a signal voltage representative of the actual heater temperature.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-03 | 1978-09-02 | 1979-03-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-03 | 1982-09-02 | 1983-03-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-03 | 1986-09-02 | 1987-03-04 | $7700.00 | Window Closed / Lapsed |