US3741709A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Solid state safety control for fuel burning apparatus
Assignee: Desa International LLC
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Filing: 1972-01-11
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Granted: 1973-06-26
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Expires: 1992-01-11
Abstract
Abstract A solid state flame sensing control circuit for a fuel burning device incorporates a thermal sensitive circuit breaker, a heating coil to energize the circuit breaker, a variable resistance device arranged to monitor and respond to a given physical condition or absence of the flame of the fuel burning device and a thyrister type unit which when energized permits sufficient current to pass through the heating coil to trip the circuit breaker. The elements are so connected that as long as the variable resistance device senses a proper flame condition the thyrister will be non-conductive; the thyrister becoming conductive when the variable resistance device, dependent on its nature, senses an absence of flame or a flame shift, or a temperature condition of such flame within the combustion chamber of the fuel burning device indicative of an absence of or improper burning. In preferred embodiment means are also provided to render the circuit insensitive to normal flame flicker.
Inventors
- 👤 L Clark
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:58
CPC Classifications
F; F23; F23N; F23N5/00; F23N5/02; F23N5/08; F23N5/082; F23N5/20; F23N5/203
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
189 words
A safety control circuit for a fuel burning device of the type producing a flame in normal operation and having electrical power means, said circuit comprising first and second leads connected to said electrical power means and connectible to a power source for energizing said electrical power means, a thermal sensitive circuit breaker connected to one said lead having in connection therewith means for tripping breaker contacts included therein, a device of the thyrister category connected to said tripping means, a variable resistance device operatively related to said thyrister device and arranged to monitor and sense a flame condition in the fuel burning device to which it is applied, means including a device having a defined firing voltage included to render said thyrister device nonresponsive to said variable resistance device when the latter is energized by a predetermined flame condition during proper combustion conditions in the related fuel burning device and responsive to a deenergizing of said variable resistance device in instances of improper flame, flame absence or failure, faulty ignition or improper combustion in said fuel burning device to trip said tripping means and open said breaker contacts.
Claim 2
Dependent Claim
189 words
A safety control circuit for a fuel burning device of the type producing a flame in normal operation and having electrical power means, said circuit comprising first and second leads connected to said electrical power means and connectible to a power source for energizing said electrical power means, a thermal sensitive circuit breaker connected to one said lead having in connection therewith means for tripping breaker contacts included therein, a device of the thyrister category connected to said tripping means, a variable resistance device operatively related to said thyrister device and arranged to monitor and sense a flame condition in the fuel burning device to which it is applied, means including a device having a defined firing voltage included to render said thyrister device nonresponsive to said variable resistance device when the latter is energized by a predetermined flame condition during proper combustion conditions in the related fuel burning device and responsive to a deenergizing of said variable resistance device in instances of improper flame, flame absence or failure, faulty ignition or improper combustion in said fuel burning device to trip said tripping means and open said breaker contacts.
Claim 3
Dependent Claim
37 words
The structure as set forth in claim 1 characterized by said device having a defined firing voltage being arranged to render said circuit insensitive to ordinary momentary changes in flame condition in the related fuel burning device.
Claim 4
Dependent Claim
27 words
The structure as set forth in claim 1 characterized by said device having a defined firing voltage being a neon tube or other device having equivalent function.
Claim 5
Dependent Claim
32 words
Apparatus as set forth in claim 1 characterized by said tripping means including a heater type coil in series with said thyrister and said variable resistance device being connected across said thyrister.
Claim 6
Dependent Claim
25 words
Apparatus as set forth in claim 4 characterized by said thyrister being a silicon controlled rectifier and said variable resistance device being a photo-sensitive device.
Claim 7
Dependent Claim
41 words
Apparatus as set forth in claim 1 characterized by said device having a defined firing voltage including means rendering the circuit insensitive to momentary change in flame condition connected between a gate of said thyrister device and said variable resistance device.
Claim 8
Dependent Claim
32 words
Apparatus as set forth in claim 6 including complementary resistor means in said circuit, connected between said tripping means and said variable resistance device and said tripping means and said thyrister device.
Claim 9
Dependent Claim
50 words
Apparatus as set forth in claim 4 characterized by said thyrister device bieng inserted in a third lead across said first and second leads in series with said tripping means and said variable resistance device being connected between said third lead and the other of said first and second leads.
Claim 10
Dependent Claim
28 words
Apparatus as set forth in claim 8 wherein said thyrister device is a silicon controlled rectifier and said variable resistance device is a photo-sensitive device sensing flame condition.
Claim 11
Dependent Claim
91 words
A structure as set forth in claim 9 including a resistor interposed between and in series with said heating coil and said rectifier, a fourth lead containing a second resistor and said photo-sensitive devicE in series, one end of said fourth lead being connected to said third lead between said heating coil and the said first resistor, the other end of the said fourth lead being connected to said second lead and the gate of said rectifier being connected to said fourth lead between said second resistor and said photosensitive device.
Claim 12
Dependent Claim
50 words
A structure as set forth in claim 10 characterized by said device having a defined firing voltage including a break-over device in a fith lead connecting between said gate and said fourth lead and providing means operable to render said circuit insensitive to ordinary flame flicker or momentary flame displacement.
Claim 13
Dependent Claim
24 words
A structure as set forth in claim 11 wherein said break-over device comprises a neon tube or the like having a defined firing voltage.
References Cited (Backward Citations)
US3537804A
Cited
US3672811A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |