US3701137A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transistorized thermocouple flame detector
Assignee: Control Design Inc
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Filing: 1970-09-29
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Granted: 1972-10-24
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Expires: 1990-09-29
Abstract
Abstract A system for detecting the presence of a burner flame in which the flame heats a thermocouple which is connected to the emitter of a transistor. The transistor is connected to conduct heavily when the thermocouple is cold and to conduct less heavily when the thermocouple is hot. A circuit which generates periodic pulses of voltage is connected to the transistor to cause it to conduct heavily upon the occurrence of each pulse, thus causing a substantial change in the conduction of the transistor only when the thermocouple is hot. This change in conduction generates a control voltage which is used to activate a control relay to control the flow of fuel to the burner.
Inventors
- 👤 William H Hulsman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 03:39
CPC Classifications
F; F23; F23N; F23N5/00; F23N5/02; F23N5/10; F23N5/102
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
173 words
In a flame monitoring system having a burner adapted to support a flame, a thermocouple adapted to be heated by said flame and a control system responsive to the voltage generated in said thermocouple, comprising: a. a transistor having a plurality of electrodes including a voltage controllable electrode, said thermocouple being connected directly to said voltage controllable electrode to impose its voltage on said voltage controllable electrode; b. first means for imposing a voltage on electrodeS of said transistor of a magnitude to cause said transistor to conduct heavily in absence of voltage being generated in said thermocouple; c. the connection from said thermocouple to said voltage controllable electrode being poled to decrease the conduction of said transistor upon generation of a voltage in said thermocouple; d. second means for supplying periodic voltage pulses to electrodes of said transistor of a magnitude to cause said transistor to conduct heavily during each such impulse; and e. third means responsive to substantial changes in conduction of said transistor to indicate the presence of said flame.
Claim 2
Dependent Claim
173 words
In a flame monitoring system having a burner adapted to support a flame, a thermocouple adapted to be heated by said flame and a control system responsive to the voltage generated in said thermocouple, comprising: a. a transistor having a plurality of electrodes including a voltage controllable electrode, said thermocouple being connected directly to said voltage controllable electrode to impose its voltage on said voltage controllable electrode; b. first means for imposing a voltage on electrodeS of said transistor of a magnitude to cause said transistor to conduct heavily in absence of voltage being generated in said thermocouple; c. the connection from said thermocouple to said voltage controllable electrode being poled to decrease the conduction of said transistor upon generation of a voltage in said thermocouple; d. second means for supplying periodic voltage pulses to electrodes of said transistor of a magnitude to cause said transistor to conduct heavily during each such impulse; and e. third means responsive to substantial changes in conduction of said transistor to indicate the presence of said flame.
Claim 3
Dependent Claim
117 words
A system as in claim 1 in which the electrodes of said transistors comprise a base, an emitter and a collector and in which a power terminal and a ground terminal adapted to be connected to a source of current are provided and in which: a. the thermocouple is connected between said emitter and said ground terminal; b. said first means comprises a circuit for deriving a first voltage from said terminals and impressing said voltage on said base and for deriving a second voltage from said terminals and for connecting said second voltage to said collector through a relatively high load resistance; and c. said second means is connected between said base and said ground terminal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |