US 4,242,079 A · Fuel ignition control system

Abstract

A fuel ignition control system including a control arrangement for operating pilot and main valves of the system the pilot valve being operated to permit a pilot flame to be established, and the main valve being operated by a pilot flame sensing circuit which includes a controlled switching device enabled in response to the charging of a capacitor to a given value to effect the operation of the main valve, the charging of the capacitor being controlled by a further controlled switching device which supplies AC current to the capacitor in the absence of a pilot flame, preventing the capacitor from charging to the given value, and which supplies DC current to the capacitor when a pilot flame is established, permitting the capacitor to charge to the given value. In an embodiment wherein the main valve is energized by a relay controlled by the flame sensing circuit, the control arrangement includes an interlock arrangement which prevents start up of the system under certain failure conditions, such as welded relay contacts. In another embodiment, the system includes an igniter circuit which has a flame responsive enabling circuit which permits the igniter circuit to be enabled and disabled independently of the flame sensing circuit.

Claims12

Dependent claims

In a fuel ignition control system including valve means operable to supply fuel to a burner for ignition to establish a flame, a control arrangement comprising activate means including first switching means operable when enabled to prepare an energizing path for said valve means, and circuit means including energy storage means for causing current to flow over a circuit path including said first switching means and first normally closed contacts, for enabling said first switching means, and flame sensing means including second switching means operable to open said first contacts and to close second contacts to complete said energizing path to energize said valve means, said activate means further including resistance means connected in parallel with said first contacts to provide a holding path for said first switching means when said second switching means operates to open said first contacts.

In a fuel ignition control system including a pilot valve operable to supply fuel to a pilot outlet for ignition to establish a pilot flame, and a main valve operable to supply fuel to a main burner for ignition by the pilot flame, a control arrangement comprising:

activate switch means operable to effect the energization of said pilot valve;
first switching means operable when enabled to complete a first circuit path;
circuit means including energy storage means responsive to said activate switch means for causing current to flow over a second circuit path including said first switching means for enabling said first switching means;
flame sensing means including second switching means operable when a flame is sensed to interrupt said second circuit path and to connect said main valve to said first circuit path for energization;
and holding circuit means connected in circuit with said first switching means to enable said first switching means to be maintained operated when said second switching means operates to interrupt said second circuit path, said first switching means being prevented from operating over said holding circuit means when said second circuit path is interrupted at the time said activate switch means operates.

2 more elements

activate means including first switching means operable when enabled to complete a first circuit path for energizing said pilot valve, circuit means including energy storage means responsive to said activate means for causing current to flow over a second circuit path including said first switching means for enabling said first switching means, and flame sensing means including second switching means operable when a flame is sensed to interrupt said second circuit path and to connect said main valve to said first circuit path to energize said main valve, said activate means further including resistance means connected in circuit with said first switching means to enable said first switching means to be maintained operated when said second switching means operates to interrupt said second path said first switching means being prevented from operating when said first circuit path is interrupted at the time said activate means operates.

Dependencies are inferred from the claim text.

Fuel ignition control system

Life of this patent

Fuel ignition control system

Life of this patent

Abstract

Claims12