Claims
- 1. Burner control apparatus for use with a fuel burner installation having an operating control switch which is actuated to produce an ignition request signal, an air flow switch which provides an air flow signal to indicate the presence of an adequate air flow through the burner, and means responsive to said burner control apparatus for controlling fuel flow, said burner control apparatus comprising:
- an electronic timing circuit for providing an ignition cycle having successive timing intervals including in sequence a purge interval, a pilot ignition interval, a pilot stabilization interval and a main fuel ignition interval;
- air means for providing an air flow through the burner during said ignition cycle;
- lockout means, responsive to a lockout signal applied thereto for a predetermined time, for terminating burner operation and stopping fuel flow to said burner installation;
- means, responsive to said operating control switch, for activating said timing circuit, including:
- a first photocoupler having a light source connected in parallel with said air flow switch and providing an output signal across its output terminals when said air flow switch is open;
- a second photocoupler having a light source connected in series with said air flow switch and providing an output signal across its output terminals when said air flow switch is closed;
- means, operative in response to an ignition request signal, for initially applying power to the timing circuit to begin an ignition cycle only if said first photocoupler output signal is present; and
- means, operative in response to an ignition request signal, for applying a lockout signal to said lockout means until the occurrence of said second photocoupler output signal;
- whereby said timing circuit is disabled to prevent further ignition cycle operation if said air flow switch is closed before said air means is operative and said lockout means is actuated to prevent further ignition cycle operation if said air flow signal is not present within a predetermined time after said air means is operative.
- 2. The apparatus of claim 1 wherein said air means includes a blower relay for applying power to a blower;
- and wherein the control apparatus further includes means for actuating said blower relay in response to the presence of a lockout signal and for maintaining said blower relay in an actuated condition thereafter.
- 3. The apparatus of claims 1 or 2 wherein said means for initially applying includes:
- a third photocoupler having a light source connected in series with said operating control switch, and having output terminals connected in series with the output terminals of said first photocoupler;
- power circuit means, responsive to a signal applied to a control terminal, for providing power on an output terminal to said timing circuit; and
- means for applying power through the series-connected output terminals of said first and third photocouplers to the control terminal of said power circuit means so that power is applied to said timing circuit in response to an ignition request signal only when said air flow switch is initially open.
- 4. The apparatus of claim 3 wherein one output terminal of said third photocoupler is connected to said power circuit means control terminal and the second output terminal of said third photocoupler is connected to said power circuit means output terminal by a diode having a polarity such that a signal is applied to said power circuit means control terminal through said diode and third photocoupler after said air flow switch closes.
- 5. The apparatus of claim 4 wherein the timing circuit includes a capacitor which is discharged to time said purge interval;
- and further including means connected to said capacitor and responsive to said first photocoupler output signal for preventing said capacitor from discharging until said air flow switch closes and removes said first photocoupler output signal.
Parent Case Info
This application is a continuation-in-part of my application Ser. No. 9,307 filed Feb. 5, 1979, entitled Burner Control System, now U. S. Pat. No. 4,243,372.
US Referenced Citations (8)
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
9307 |
Feb 1979 |
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