Johnson Controls Gmbh

Johnson Service Company

Russell B Matthews

Thomas E Hayes

George Rudich, Jr

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 establishes 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.

Apparatus for fuel ignition system including complete cycling of flame

A control circuit for a fuel supply and ignition control system controls the operation of pilot and main valves of the system and of a motor which controls the positioning of a vent stack damper plate to normally close the vent stack and to open the vent stack at the start of each ignition cycle. At the start of each ignition cycle, a start relay is operated to energize the pilot valve and a spark generator for a trial for ignition interval defined by the excursion time of the damper plate as it is driven to the open position. When the pilot fuel is ignited, a flame sensing circuit operates a flame relay which completes a holding path for the pilot valve and when the damper plate reaches the fully open position, limit switches connect the main valve to the holding path and deenergize the drive motor and the start relay. If a pilot flame is not sensed before the end of the trial for ignition period, one of the limit switches deenergizes the pilot valve, and the start relay prevents reenergization of the drive motor, locking out the system. The control circuit includes a relay checking arrangement whereby start-up is prevented if for any reason the flame relay is operated at the start of an ignition cycle.

Fuel ignition and stack damper control circuit

A fuel supply and ignition control system for controlling the operation of pilot and main valves in an intermittent pilot type system. At the start of an ignition cycle, the pilot valve is operated to supply fuel to a pilot outlet for ignition by sparks generated by a spark generating circuit. When the pilot fuel is ignited, the pilot flame bridges the spark gap, and a flame sensing network, which is connected in circuit with the spark electrodes, generates a flame signal which is applied to an enabling circuit which responsively effects operation of the main valve. The enabling circuit includes a controllable switching device which in one embodiment, is maintained disabled in the absence of a flame signal and is enabled to cause a flame relay to operate and energize the main valve when a flame signal is provided. In another embodiment, the controllable switching device is enabled in the absence of a flame signal and causes an SCR device to conduct, providing a low impedance energizing path for the pilot valve operate winding and a shunt path around the main valve operate winding. When a flame bridges the spark gap, the flame signal disables the switching device so that the SCR device is rendered non-conducting, interrupting the shunt path around the main valve winding allowing the main valve to operate.

Fuel supply and ignition control system employing flame sensing via

An ignition system for use with a source of dc (or full-wave-rectified) power without the need for an inverter includes a flame sensing relay and a checking relay interlocked to achieve lockout if the proper starting sequence or timing are not met or if a flame-out occurs during operation. The checking relay is energized in response to a call-for-heat signal to isolate the flame detection circuitry from its source and commence a trial-for-ignition period in the flame detection circuitry which includes a timing circuit. The timing circuit actuates the flame-sensing relay during the trial-for-ignition period. The flame sensing relay energizes the fuel valve and a spark generator to ignite the fuel. If a flame is detected during the trial-for-ignition period by a flame probe, the timing circuit is disabled and operation continues until the call for heat is terminated as long as the flame is sensed. Another circuit senses flame at the spark gap and disables the spark gap generator after a flame is established. If a flame-out or fuel interruption occurs, the spark generator is re-energized, and the timing circuit is enabled to commence a re-ignition timing period, after which the flame relay is disabled and the system is locked out if ignition is not proved. Once locked out, the system can be re-started only by cycling the thermostat or a remote switch. A minimum re-cycle time is defined by a charging circuit connected to the timing circuit when either switch is re-cycled.

Direct ignition system for gas appliance with DC power source

A control arrangement for a fuel ignition system having pilot and main valves in which the energization of the operate windings of the pilot and main valves, which are connected in series, is controlled by a silicon controlled rectifier. The SCR is enabled at the start of each ignition cycle by trigger pulses provided by a pulse generating circuit and when enabled, the SCR provides a shunt circuit path around the main valve winding permitting the pilot valve winding to be energized at its operating level effecting pilot valve operation and preventing the main valve from operating. When a pilot flame is provided, a capacitor of a flame sensing network is charged by flame rectified current, generating an inhibit signal for the pulse generating circuit which causes the SCR to be cut off, interrupting the shunt path to allow the main valve winding to be energized, effecting main valve operation. A trial for ignition timer diactivates the pilot valve and locks out the system if the pilot fuel fails to be lit before the end of a trial for ignition interval, the ignition timer being rendered ineffective in response to disabling of the SCR when a pilot flame is sensed. In one embodiment, the ignition timer comprises a time delay relay which is resettable by cycling the thermostat contacts open and closed. In another embodiment, the ignition timer comprises a thermal cutout switch mounted on the pilot valve and heated by the pilot valve operate winding.

Solid state ignition control

An arrangement for a direct ignition type fuel ignition system includes a capacitive timing network which enables a flame relay to operate during a trial for ignition interval, energizing a fuel valve to supply fuel to a burner for ignition, and a flame sensing circuit which causes the flame relay and the fuel valve to be maintained operated only if a flame is sensed before the end of the trial for ignition interval. In the absence of a flame, a diode, back biased by the timing signal, decouples the flame sensing circuit from the timing network. When a flame is established, a further diode, back biased by a control signal provided by the flame sensing circuit, decouples the timing network from the flame sensing circuit. In an embodiment wherein the charging time of a capacitor defines the trial for ignition interval, a fast reset circuit provides rapid discharge of the timing capacitor when power is removed from the timing network. In another embodiment, wherein the discharge time of a capacitor defines the trial for ignition interval, a checking relay, energized over normally closed contacts of the flame relay, operates to disconnect the capacitor from a source of charging current and complete a discharge path for the capacitor enabling the timing network to generate the timing signal. The checking relay is prevented from operating, thereby maintaining the system locked out, if the flame relay is operated at the start of an ignition cycle.

Fuel ignition control arrangement having a timing circuit with fast reset

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.

Fuel ignition control system

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.

Method and apparatus for fuel ignition system including complete cycling

A control arrangement for a pilot ignition type fuel ignition system includes a first switch device which effects energization of a pilot valve at the start of an operating cycle to supply fuel to a pilot outlet for ignition to provide a pilot flame. The first switch device is enabled by a control circuit which in turn is enabled over a path provided by a second switch device. The second switch device is enabled by a flame sensing circuit when a pilot flame is established and operates to effect energization of a main valve and to interrupt the enabling path for the control circuit, and a further flame sensing circuit maintains the first switch device, and thus the pilot valve, operated following operation of the second switch device.

Fuel ignition control arrangement employing dual flame sensors

A control arrangement for a direct ignition type fuel ignition system including a timing circuit having a timing capacitor which charges in response to application of power to the system defining a trial for ignition interval during which a controlled switching device is enabled to operate a flame relay to energize a fuel valve to supply fuel to a burner for ignition by sparks provided by a spark generator, the controlled switching device being disabled, deenergizing the flame relay when the timing capacitor becomes fully charged before the fuel is ignited, and the controlled switching device being maintained enabled through the action of a flame sensing circuit which is coupled to the timing circuit only when a flame is established. The control arrangement includes a reset circuit having a discharge network which enables rapid discharge of the timing capacitor whenever the system is deactivated, the discharge network being normally decoupled from the timing capacitor, and being coupled to the timing capacitor when power is disconnected from the reset circuit. In one embodiment, the fuel valve is energized over a path provided by contacts of the flame relay and contacts of a checking relay, which is energized over normally closed contacts of the flame relay at the start of each operating cycle, the checking relay also enabling the timing circuit and the spark generator.

A fuel ignition system of the pilot ignition type including a control circuit for operating pilot and main valves of a redundant valve assembly, the control circuit having control relays which provide an interlock on start-up to prevent the energization of the valves under certain failure conditions, the control circuit including a flame sensing circuit which is operable to prevent start-up of the system when a flame is provided as the result of a leak condition for the pilot valve, and to terminate an ignition cycle causing complete shut off of fuel whenever a flame is provided as the result of a leak condition for the main valve.

Fuel ignition system having interlock protection and electronic valve

A control circuit for a fuel ignition system of the direct ignition type for providing an interlock on start-up to prevent the energization of a fuel supply valve of the system under certain failure conditions includes an interlock relay which is energized, after a predetermined delay, over normally closed contacts of a flame relay to control a timing network to cause a flame sensing circuit to enable the flame relay to energize the valve during a trial for ignition interval defined by the timing network, the flame sensing circuit maintaining the flame relay, and thus the valve, energized when a flame is provided during the trial for ignition interval, the energization of the valve and the interlock relay being prevented if the normally closed contacts of the flame relay are open on start-up, and the delayed operation of the interlock relay preventing lockout of the system following momentary loss of power.

Direct ignition system with interlock protection

A self-checking fuel ignition system of the pilot ignition type including a sampling flame sensor which effects periodic testing of the operability of a spark generating circuit to provide ignition sparks, and an energizing circuit which operates independently of the spark generating circuit but under the control of the flame sensor, to control the operation of fuel valves of the system and to effect the shut down of the system for loss of flame or ignition spark.

Proven pilot fuel ignition system with sampling flame sensor

A control arrangement for a fuel ignition system including redundant pilot and main valves, includes a thermal heat sensor mounted on a heat exchanger or in an exhaust stack of main burner apparatus and having a heating element which is energized in response to operation of thermostatically controlled contacts to close associated contacts to effect energization of the pilot valve permitting fuel to be supplied to a pilot outlet and the main valve which is operated when a pilot flame is established, the heating element being deenergized when the main valve is operated and the heat sensor being responsive to heat from the main burner to maintain the contacts closed maintaining the pilot valve energized. The heat sensor responds to a flame out condition to deenergize the pilot valve, thereby interrupting fuel flow to main valve.

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Goshen, IN, United States of America

Russell B Matthews