Combustion – Process of combustion or burner operation – Starting or shutdown procedure
Patent
1989-10-12
1992-02-04
Jones, Larry
Combustion
Process of combustion or burner operation
Starting or shutdown procedure
431 72, 126 39N, 25112901, 25112902, 25112904, F23N 520
Patent
active
050855743
ABSTRACT:
A fail-safe gas valve driver circuit controlling the gas supply line of a gas burner, which circuit in its essential circuit elements (FIG. 1) includes an appropriate switching means (S1) effectively feeding a pulsed DC wave form into the rest of the valve relay driver circuit, operatively consisting only of a capacitor (C1) in series with a gas valve relay (K1), which in turn is in parallel with a diode (D1). In operation, the valve relay coil is energized by charging the capacitor with the switch connected to a positive DC voltage source (V.sub.dc ; FIG. 1A), and then grounding the positive end of the capacitor (switch connected to ground) applying a negative voltage across the coil of the relay (FIG. 1B). When the capacitor is again connected to the positive DC voltage source by the switch, the current in the relay coil is sustained by the diode (FIG. 1C). The switch is operated at a sufficiently high rate so the current in the relay coil has insufficient time to decay significantly during the charging cycle of the capacitor before being replenished during the capacitor discharge cycle. With this circuitry the gas supply valve (G.V.) will always go to, or be maintained in, a closed position, regardless of what component(s) of the valve relay driver circuit might fail or deteriorate. Any inadvertent supply of gas to the burner due to any component failure is avoided without any component redundancy. Two exemplary, transistor switching circuits are described (FIGS. 2 & 3).
REFERENCES:
patent: 3902839 (1975-09-01), Matthews
patent: 3986814 (1976-10-01), De Mere
patent: 4034235 (1977-07-01), Wade
patent: 4413303 (1983-11-01), Cheary et al.
patent: 4828484 (1985-05-01), Youtz
patent: 4836770 (1989-06-01), Geary
patent: 4842510 (1989-06-01), Grunden et al.
patent: 4865538 (1989-09-01), Scheele et al.
patent: 4872828 (1989-10-01), Mierzwinski et al.
Hamilton Standard Controls Inc.
Jones Larry
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