US3759654A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal operator for ignition proving system
Assignee: Robertshaw Controls Co
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Filing: 1971-11-12
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Granted: 1973-09-18
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Expires: 1991-11-12
Abstract
Abstract An improved operator is disclosed which greatly amplifies the relatively small expansion and contraction movements of a heat expansible wire connected in series with an electric igniter having a positive coefficient of resistance. As the igniter changes temperature its electrical resistance also changes causing a difference in current flow through the wire and accordingly an expansion or contraction thereof. Lever means attached to the wire amplify this movement and utilize it to selectively actuate switches controlling energization of both the electric igniter and an electrically actuated fuel valve providing fuel to a burner.
Inventors
- 👤 J Clifford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 20:51
CPC Classifications
F; F23; F23Q; F23Q1/00; F23Q1/02; F23Q1/06; F23Q3/00
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
174 words
In an ignition proving system for a fuel burner comprising input means connected to a source of electricity; electric igniter means positioned in igniting proximity to the burner, said electric igniter means having a positive temperature coefficient of resistance such that current flow therethrough is dependent on the temperature on the electric igniter; electrically actuated valve means adapted to control flow of fuel to the burner; and switch means connected between said input means and both said electric igniter means and said valve means; an improved thermal actuator means comprising current sensing means including a heat expansible wire connected in series with said electric igniter to be heated by current passing therethrough; said wire being attached at each end to a stationary support; and lever means pivotally connected to a support at one end, said lever means including an integral leg portion depending from a point intermediate the ends of said lever means and engaging said wire, and means for selectively actuating said switch means in response to expansion and contraction of said wire.
Claim 2
Dependent Claim
174 words
In an ignition proving system for a fuel burner comprising input means connected to a source of electricity; electric igniter means positioned in igniting proximity to the burner, said electric igniter means having a positive temperature coefficient of resistance such that current flow therethrough is dependent on the temperature on the electric igniter; electrically actuated valve means adapted to control flow of fuel to the burner; and switch means connected between said input means and both said electric igniter means and said valve means; an improved thermal actuator means comprising current sensing means including a heat expansible wire connected in series with said electric igniter to be heated by current passing therethrough; said wire being attached at each end to a stationary support; and lever means pivotally connected to a support at one end, said lever means including an integral leg portion depending from a point intermediate the ends of said lever means and engaging said wire, and means for selectively actuating said switch means in response to expansion and contraction of said wire.
Claim 3
Dependent Claim
107 words
The invention as claimed in claim 1 wherein said wire has a cool contracted state defining a first position for said lever means and a hot expanded state defining a second position for said lever means, said switch means including first and second switches, said first switch connected to energize said igniter means and said first and second switches connected in series to energize said valve means, said first switch being normally closed and said second switch being normally opened when said lever means is in said first position whereby said valve means will not be energized to open until after said igniter means reaches ignition temperature.
Claim 4
Dependent Claim
43 words
The invention as claimed in claim 1 wherein said electric ingiter means has a high resistance at ignition temperatures, further comprising voltage responsive means connected in parallel with said igniter means and operatively connected to hold said switch means in a predetermined condition.
Claim 5
Dependent Claim
44 words
The invention as claimed in claim 3 wherein said switch means comprises first and second switches, said first switch being operatively connected with said lever means and said voltage responsive means, said second switch being connected to be actuated by said lever means only.
Claim 6
Dependent Claim
33 words
The invention as claimed in claim 3 wherein said voltage responsive means includes a holding coil and an armature controlled by said coil and connected to hold said first switch in closed condition.
References Cited (Backward Citations)
US3619096A
Cited
US3660005A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-17 | 1977-03-19 | 1977-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-17 | 1981-03-19 | 1981-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-17 | 1985-03-19 | 1985-09-18 | $7700.00 | Window Closed / Lapsed |