US 4,230,444 A · Method and apparatus for fuel ignition system including complete cycling of flame relay prior to trial for ignition

Abstract

When a call for heat is established, a flame relay is actuated for a predetermined time by means of a cycling timer. Upon this initial actuation, the flame relay inhibits a checking relay and initializes a trial-for-ignition (or simply "ignition") timer. After the cycling timer times out and the flame relay has been completely cycled, which established operativeness of the flame relay and flame sensing circuitry, the checking relay is enabled and actuated for the ignition period. The checking relay then actuates the pilot valve and a spark generator to start a pilot flame. If a flame is sensed, before the ignition timer times out, the flame relay actuates the main valve and establishes a holding current for the ignition timer so that the checking relay continues to be energized. If a flame is not sensed during the trial period, the ignition timer disables the checking relay, thereby de-energizing the pilot valve before the main valve is opened. If there is a fault in the flame relay or flame sensing circuitry, the checking relay is inhibited from operating. Both timers are preferably electronic timing circuits using capacitors in such a manner that circuit faults do not cause system malfunction. In an alternative embodiment, separate flame sensing circuits control the operation of the flame relay and the ignition timer.

Claims23

Dependent claims

In a fuel ignition system including a pilot valve operable when energized to supply fuel to a burner for ignition by sparks provided by a spark generating means to provide a pilot flame, and a main valve operable when energized to supply fuel to said burner for ignition by the pilot flame, a control arrangement comprising:

activate means for generating a start signal to initiate an ignition cycle;
timing circuit means including a capacitor which is charged to a given value at the start of the ignition cycle and then discharged, permitting said timing circuit means to generate an enabling signal during a trial for ignition interval defined by the discharge time of said capacitor;
first switching means for controlling the operation of said pilot valve;
actuating means responsive to said enabling signal to enable said first switching means to energize said pilot valve during said trial for ignition interval;
said timing circuit means normally terminating said enabling signal at the end of said trial for ignition interval to disable said actuating means whereby said first switching means is disabled, and flame sensing means operable when a flame is provided at said burner during said time interval to generate a control signal for application to said timing circuit means to cause said timing circuit means to continue to provide its enabling signal after the end of said trial for ignition interval to maintain said actuating means and thus said first switching means operated after said trial for ignition interval, said flame sensing means including control means and second switching means controlled by said control means to be enabled when a flame is sensed during said trial for ignition interval to energize said main valve.

2 more elements

In a fuel ignition system including a pilot valve for supplying fuel to a burner for ignition to provide a pilot flame, and a main valve for supplying fuel to said burner for ignition by the pilot flame, a control arrangement comprising:

ignition timing means operable from an initial state to provide a timing signal for a predetermined interval of time and to terminate said timing signal at the end of said time interval;
first switching means enabled by said timing signal to energize said pilot valve;
second switching means;
flame sensing means operable when a flame is provided during said time interval to enable said second switching means to prevent said ignition timing means from terminating its timing signal and to energize said main valve;
and cycle timing means effective at the start of an operating cycle to enable said second switching means to set said ignition timing means to its initial state and to then disable said second switching means;
said first switching means preventing energization of said main valve while said second switching means is enabled by said cycle timing means.

3 more elements

Apparatus for controlling the operation of a pilot valve actuated by a pilot valve solenoid and a main valve actuated by a main valve solenoid to supply fuel to a pilot outlet and a main burner for ignition, said apparatus comprising:

first switching means;
cycle timer circuit means responsive to a call for heat signal for enabling said first switching means for a predetermined time period and for disabling said first switching means at the end of said predetermined time period;
ignition timer circuit means responsive to the operation of said first switching means for generating a timing signal representative of a desired trial-for-ignition period;
second switching means;
and circuit means responsive to said timing signal and to the disabling of said first switching means for enabling said second switching means to energize said pilot valve solenoid to cause fuel to flow to said pilot outlet.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for fuel ignition system including complete cycling of flame relay prior to trial for ignition

Life of this patent

Method and apparatus for fuel ignition system including complete cycling of flame relay prior to trial for ignition

Life of this patent

Abstract

Claims23