US4235587A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flame responsive control circuit
Assignee: Honeywell Inc
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Filing: 1979-04-09
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Granted: 1980-11-25
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Expires: 1999-04-09
Abstract
Abstract A flame responsive control circuit means has been disclosed which responds to the flame in a burner. The response is to the sudden rate of change of the resistance or impedance of a photocell upon the loss of flame. The two embodiments disclosed both utilize a rate of change sensing means to determine that a loss of flame has occurred. If a loss occurs, ignition is reinstituted immediately and the system either operates normally or locks itself out in a safety shut down.
Inventors
- 👤 Gregory M. Miles
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:26
CPC Classifications
F; F23; F23N; F23N5/00; F23N5/02; F23N5/08; F23N5/082; F23N5/20; F23N5/203; F23N2227/00; F23N2227/28; F23N2229/00; F23N2239/00; F23N2239/06
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
201 words
A flame responsive control circuit means adapted to be connected to flame responsive cell means to provide an improved, rapid response to the loss of a flame in burner means and to initiate ignition means upon said flame loss, including: rate of change sensing means having input means adapted to be connected to said cell means to respond to a change in the impedance of said cell means; said rate of change sensing means including amplifier means having output means connected to ignition control switch means; said rate of change sensing means being responsive to the application of an energizing potential to said control circuit means to cause said control circuit means and said ignition control switch means to initiate the operation of said ignition means; said rate of change sensing means further responsive to a rate of change in the impedance of said flame responsive cell means to also initiate said ignition means upon said cell means being first exposed to a flame and subsequently changing impedance rapidly due to the loss of said flame; and fuel control means connected to initiate a supply of fuel to said burner means in response to an absolute potential at said cell means.
Claim 2
Dependent Claim
201 words
A flame responsive control circuit means adapted to be connected to flame responsive cell means to provide an improved, rapid response to the loss of a flame in burner means and to initiate ignition means upon said flame loss, including: rate of change sensing means having input means adapted to be connected to said cell means to respond to a change in the impedance of said cell means; said rate of change sensing means including amplifier means having output means connected to ignition control switch means; said rate of change sensing means being responsive to the application of an energizing potential to said control circuit means to cause said control circuit means and said ignition control switch means to initiate the operation of said ignition means; said rate of change sensing means further responsive to a rate of change in the impedance of said flame responsive cell means to also initiate said ignition means upon said cell means being first exposed to a flame and subsequently changing impedance rapidly due to the loss of said flame; and fuel control means connected to initiate a supply of fuel to said burner means in response to an absolute potential at said cell means.
Claim 3
Dependent Claim
75 words
A flame responsive control circuit means as described in claim 1 wherein said fuel control means has output means including a solid state switch, a relay, and a safety switch heater element connected in a series circuit wherein current conduction of said solid state switch energizes said relay and said heater element; and a normally open relay contact operated by said relay to latch said relay into a further circuit upon operation of said relay.
Claim 4
Dependent Claim
44 words
A flame responsive control circuit means as described in claim 1 wherein said cell mens is paralled by a resistor whose value is higher than the resistance of said cell means when said cell means is exposed to a flame in a fuel burner.
Claim 5
Dependent Claim
35 words
A flame responsive control circuit means as described in claim 1 wherein said input means for said rate of change sensing means includes said cell means and a capacitor in different legs of a bridge.
Claim 6
Dependent Claim
36 words
A flame responsive control circuit means as described in claim 4 wherein said amplifier means includes time delay means to delay the de-energization of said ignition means upon said cell means sensing the presence of flame.
Claim 7
Dependent Claim
31 words
A flame responsive control circuit means as described in claim 5 wherein said ignition control switch means includes a relay having a normally open contact for control of said ignition means.
Claim 8
Dependent Claim
75 words
A flame responsive control circuit means as described in claim 6 wherein said fuel control means has output means including a solid state switch, a relay, and a safety switch heater element connected in a series circuit wherein current conduction of said solid state switch energizes said relay and said heater element; and a normally open relay contact operated by said relay to latch said relay into a further circuit upon operation of said relay.
Claim 9
Dependent Claim
43 words
A flame responsive control circuit means as described in claim 7 wherein said cell means is paralleled by a resistor whose value is higher than the resistance of said cell means when said cell means is exposed to a flame in a burner.
Claim 10
Dependent Claim
29 words
A flame responsive control circuit means as described in claim 8 wherein said cell means is a cadmium sulfide photocell; and said fuel burner means is an oil burner.
Claim 11
Dependent Claim
63 words
A flame responsive control circuit means as described in claim 1 wherein said input means for said rate of change sensing means includes a coupling capacitor between said cell means and an input for said amplifier means; and said amplifier output means change state in response to a current coupled through said capacitor upon a change in the impedance of said cell means.
Claim 12
Dependent Claim
31 words
A flame responsive control circuit means as described in claim 10 wherein said ignition control switch means includes a relay having a normally open contact for control of said ignition means.
Claim 13
Dependent Claim
75 words
A flame responsive control circuit means as described in claim 11 wherein said fuel control means has output means including a solid state switch, a relay, and a safety switch heater element connected in a series circuit wherein current conduction of said solid state switch energizes said relay and said heater element; and a normally open relay contact operated by said relay to latch said relay into a further circuit upon operation of said relay.
Claim 14
Dependent Claim
45 words
A flame responsive control circuit means as described in claim 12 wherein said cell means is paralled by a resistor by whose value is higher than the resistance of said cell means when said cell means is exposed to a flame in a fuel burner.
Claim 15
Dependent Claim
29 words
A flame responsive control circuit means as described in claim 13 wherein said cell means is a cadmium sulfide photocell; and said fuel burner means is an oil burner.
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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) | 1983-11-25 | 1984-05-26 | 1984-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-11-25 | 1988-05-26 | 1988-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-11-25 | 1992-05-26 | 1992-11-25 | $7700.00 | Window Closed / Lapsed |