GB2317684A - An ignition system of a gas heating appliance - Google Patents

Abstract

A control system of or for a gas heating appliance comprises first flame failure valve 41 which requires the application of operator initiable force (directly or via remote control means) on a displacing means thereof to open it and which may thereafter be maintained open by a "flame present" signal from a flame sensor 47, associated with a pilot light jet and/or associated with a main gas burner of the appliance which is operatively connected to the flame failure valve 41 to maintain such open only when a flame is present, and an electronic spark ignition circuit 46 actuable/energisable upon the application of said force, such as by operation of said displacing means by the operator into the open position of the flame failure valve to initiate spark ignition, characterised by the feature that a time delay cut-off means 54,46 is connected to the flame failure valve and actuable also by the displacement of the displacing means, so that said time delay cut-off holds the flame failure valve open for a predetermined time.

Description

AN IGNITION SYSTEM OF A GAS HKATING APPLIANCE The present invention relates to an ignition system of a gas heating appliance including a flame failure device comprising a valve which requires the application of an external physical force of an operative/user to open it, but which may thereafter be maintained open by "flame present" signals from a flame sensor, such as a small electric current from a thermocouple, and is a modification or improvement of the subject of our UK Patent 2233756 UK Patent 2233756 discloses a gas heater appliance of the kind described above having a variable flow valve (12) in gas series with the flame failure valve (11), and a common manual operator (22, 24, 25 and 32), movement of which to an "ignition" setting applies the force required to open the flame failure valve (11), places the variable flow valve (12) at an "ignition" flow rate and initiates spark ignition. The flame failure device of the valve (11) referred to above comprises an electro-magnet (17) which is energisable to maintain an armature (18) adjacent thereto when it has been physically displaced by an operator/user displacing physically an opening member or push rod (21) which also acts to lift the valve head (19) off its seat and open the valve (11). When the current to the electromagnet (17) is disconnected, the valve (11) is biased such as by means of a spring into the closed position so as to act as a fail-safe device and such a valve will be referred to herein and is known as a "magnetic-valve" or "Magvalve". Such Mag-valves are well known and very reliable in their closing operation once the current to the electromagnet is disconnected. Also, such Mag-valves require only a small current, normally direct current, to operate.

It is known for control valves to be provided in gas appliances actuable by means of a solenoid powered by an AC mains electricity supply and are operable such that when energised the solenoid causes the valve closure member to lift off its seat and be kept open as long as the main supply is maintained. However, such solenoid valves tend to be somewhat unreliable in that residual magnetism may build up in the housing or surrounding materials such that they do not close properly once the power source is cut off and it is a safety requirement as a precaution that two such solenoid devices be provided adjacent each other which leads to additional costs and bulk.

In British Patent in the name of Carver there is disclosed a gas appliance including a rechargeable battery wherein the battery is rechargeable by means of current derived from the thermocouple located in the burner region.

There is an ever increasing requirement for improved safety of operation of gas appliances and also with this a requirement for simplicity of operation of the controls.

According to the present invention a control system of or for a gas heating appliance comprises a magneticvalve or Mag-valve, which comprises a flame failure valve of the type which requires the application of the external force of an operator/user on a push member thereof to open it but which may thereafter be maintained open by a "flame present" signal from a flame sensor, and a flame sensor associated with a pilot light jet and/or associated with a main gas burner of the appliance which is electrically connected to the Mag-valve to maintain such open only when a flame is present, and an electronic spark ignition circuit actuable/energisable upon the pushing of said push member by the operator into the open position of the Mag valve to initiate spark ignition, characterised by the feature that a power supply circuit with time delay cut off is connected to the Mag-valve and energisable also by the pushing of the push member by a user or otherwise displacing the push member so that said supply circuit with time delay cut off holds the Mag-valve open for a predetermined time.

It will be appreciated that the heating appliance defined above maintains the Mag-valve in the open position for a predetermined period to permit ignition by the electronic ignition means but which is de-energised after a predetermined period whereupon if no current is flowing from the flame sensor, the Mag-valve automatically cuts off the gas supply in the event of failure of ignition.

Thus the appliance of the present invention avoids the need for the operator to hold down the push member for a pre-determined period during the ignition stages as the Mag-valve is automatically held open for a pre-determined period. This considerably facilitates use and operation of the appliance and enables use of a slider control.

The Mag-valve when de-energised automatically closes and is located in the gas inlet pipe or duct leading to a pilot light jet and/or the main gas burner and when closed cuts off the gas supply.

The main control of the gas flow for the heating appliance will comprise a variable flow valve which is -preferably in gas series with the Mag-valve and may be similar to that disclosed in our GB Patent 2233756 requiring rotary control or may be an integral structure with the Mag-valve.

Where the control system is similar to that illustrated in the drawings of our GB Patent 2233756, an ignition micro switch (such as 33 in Fig 1 of the Patent) which energises the electronic spark ignition system (not shown) and preferably according to the present invention will also energise the electro-magnet (17) of the Mag-valve for a predetermined period and, with successful ignition, the Mag-valve will be maintained open as a result of current flowing from the temperature probe (15) such as a thermocouple located adjacent the gas burner or adjacent a pilot light jet.

Preferably, the temperature probe will be associated with a pilot light jet and the push member of the Mag-valve or associated displacement means or member (22, 24, 25) therefor may be coupled/linked to control the variable flow valve and the displacement means or member biased to move in a direction slightly away from the push member when released and with said variable flow valve being such that when the displacement member is operatively displaced to open the Mag-valve, the variable flow valve is in a position where no gas flows to the main gas burner but gas does flow to the pilot light jet, and such that on release of the displacement member it is displaced under the action of the biasing means to a position where it also causes the variable flow valve to move into an open setting position and, preferably, its lowest setting position.

Thus during the sparking ignition, gas is controlled so as only to flow to the pilot light jet and not to the main gas burner.

If the flame failure device/valve can be held open for a predetermined period by means other than an electronic time delay circuit, then such should be considered as falling within the scope of the present invention, for example, a mechanical latching means/device may be provided and delayed time release device.

The Mag-valve may be energisable to be maintained open whilst a flame is present by current from a thermocouple located adjacent the pilot and/or main gas burner although instead of a thermocouple other devices such as temperature sensing thermostats or cut-outs (TTB's) may be provided adjacent the main burner - especially if no pilot is used although it is believed most likely the present invention will be utilised with a thermocouple being associated with an oxygen depletion sensing pilot jet (ODS pilot).

Where reference is made to the electronic spark ignition such as to be energised by microswitch 33 in Fig. 1 of Patent 2233756, whilst such may be controlled to operate for a pre-determined period, most electronic ignition systems currently used are of the "spark reignition" type system which continues sparking until a heat sensor determines ignition has taken place to de-energise the ignition circuit.

In a preferred embodiment the control system of the invention includes a second valve located downstream thereof between the first mentioned Mag-valve and the main burner, with said second valve being biassed to be normally open to allow gas flow to the burner and being also displaceable by said push member into its closed position.

Preferably time delay means are provided to hold said valve in its normally closed position for a predetermined time or until released by a flame present signal from a sensor adjacent the pilot flame and/or burner flame.

Also according to the present invention, the present invention relates to a gas heating appliance including an ignition control system including a normally open valve upstream of the main gas burner of the appliance which enables gas to normally flow to the burner, and wherein said normally open gas valve is such as to be capable of being held closed during ignition. Preferably said valve is a normally open Mag-valve (magnetically positionable valve) wherein the electro-magnet holds the valve closed. However, it is also envisaged possible instead to utilize a fluid filled flame failure but normally closed valve in place of the normally open valve and such as are often used in gas cookers such as in the oven wherein the fluid such as mercury or water or alcohol on being acted on by the heat of the ignited pilot, generates pressure to act to move the valve into the open position.

The gas heating appliance of the present invention and particularly the electric/electronic controls therefor will preferably be connectable to a battery or batteries and preferably to at least one rechargeable battery which is rechargeable from an electric energy generator/thermoelectric generator such as a thermocouple energised by the flame of the appliance. Mag-valves have the advantage of operating on a very low current such as 200 to 250 milliamps and it is envisaged according to the present invention that once flame ignition has taken place an electric switching control preferably the recharging circuit will receive power from the thermocouple but will coupled such that the recharging current never takes current from the Mag-valve to accidentally close such.

Preferably a current limiter which does not use much power is utilised to ensure the battery is not drained. If appropriate, a second thermocouple may be provided solely for the purpose of charging the battery. It is important .the Mag-valve supply is not interrupted at all by the recharging current since such could inadvertently act to cause it to close.

Also according to the present invention there is provided a gas valve for use in a gas appliance wherein the valve closure member of the valve is biassed into a normally open position and wherein holding means are provided to hold the valve closure member in the closed position for a predetermined time or for as long as said holding means are energised. The holding means may be a mechanical timed release device or other means but preferably is an electro-magnet and the valve operates with the action of a Mag-valve.

The invention will be described further, by way of example, with reference to the accompanying drawings in which: Figs. 1A, 1B and 1C are schematic illustrations of a known thermo-electric valve/Mag-valve which might be incorporated in a gas appliance of the present invention and wherein an electric energising circuit will be actuable upon displacement of the push button to maintain a power supply to the electro-magnet of the Mag-valve for a predetermined period to permit ignition to take place; Fig. 2 is a schematic illustration of a known control valve with thermocouple and to which a battery may be connected to the second thermocouple position; Figs. 3, 4 and 5 correspond to Figs. 1, 2 and 3 of GB 2233756 but in Fig. 3 there is a schematic illustration of the additional energising circuit with time delay cutoff for the electro-magnet (17) according to the present invention.

In Figs. 1A, 1B and 1C, there is schematically illustrated a thermoelectric valve/Mag-valve comprising a housing 1 divided into two chambers 2 and 3 with a gas inlet 4 and a gas outlet 5 to the gas burner (not shown).

The housing 1 is divided into the two chambers 2,3 by the dividing wall 6 forming a valve seat 7 for the spring biased valve closure member 8 of the Mag-valve 9 with the dividing wall 6 also acting as a through passage 10 to the second chamber 3 of the housing 1 with the dividing wall 6 also acting as an outlet duct means 11 to a pilot light jet 12. The Mag-valve/electro-magnet 9 connected by electric leads 13 to a thermocouple 14 located to be in the position of the flame 15 of the pilot 12 and when heated energises the electro-magnet.

In Fig. 1A the valve is shown in the closed position with the spring 8A biasing the valve closure member 8 of the Mag-valve 9 against its seat 7. A push member is provided comprising a button 16 which may be manually or foot operated by the user of the appliance (not shown) and which has a shaft leading to an enlarged head 17' displaceably mounted in a sleeve 18 with a spring 19 biasing the button 16 outwardly into the position shown in Fig. 1A and acting against one partially closed end 18' of the sleeve 18 and against the button 16. The sleeve 18 is fixedly sealed in the end of the housing 1 and the stem 17 is sealed by means (not shown) to prevent the escape of gas. Around the outside of the sleeve 18 but within the housing 1 forming the second chamber 3 of the housing 1 a compression spring 20 is provided which acts on a second valve closure member 21 through which the stem 17 is slidingly and sealably displaceable and the second valve closure member 21 is biased into its valve closing position (Fig. 1B) against a valve seat 21' at the other end of the interconnecting duct 10 as shown in Fig. 1B. The relative strengths of springs 19 and 20 and are such that the push member 16 will normally assume the position shown in Fig. 1 but when the button 16 is displaced as shown in Fig. 1B to open the Mag-valve 9, the second valve closure member 21 is biased against the valve seat 21' in the second chamber 3 to seal such so that gas flows through the first chamber 2 and via duct 11 to the pilot jet 12 in this position.

When the button 16 is displaced into the housing as shown in Fig. 1B, an actuating member 16' acts on a microswitch 22 and closes a Mag-valve energising circuit (not shown in great detail and simply schematically) and energises the electro-magnet 9' of the Mag-valve 9 for a predetermined period via an energising and time delay circuit 23 and at the same time electronic spark ignition is initiated by a reignition circuit (not shown) such that when the pilot 12 is ignited as flame 15 and the thermocouple 14 heated sufficiently, a current will flow from the thermocouple 14 to maintain the Mag-valve 9 open for as long as the pilot jet is lit.

In Fig. 1B, the push member/button is shown having been released and the pilot light ignited and gas permitted to flow to the main gas burner (not shown).

In Fig. 2 a standard circuit for a dual thermocouple is illustrated which can be modified by replacing the second thermocouple with an energising circuit 24 with time delay to produce a control according to the invention.

In Fig. 3 as a modification of Fig. 1 of GB 2233756 the micro switch 33 is schematically illustrated connected to an electronic spark ignition circuit 25 and also to a Mag-valve energising circuit 26 with time delay.

A Mag-valve normally has very precisely machined surfaces which abut when in the open position.

A preferred embodiment of the invention is schematically illustrated in Fig. 4 and is an ignition system of a gas appliance (not shown) and comprises a valve housing 40 including two flame failure devices in the form of two thermo-electric/Mag-valves 41 and 42 with normally closed valve 41 being in the gas supply passages 43, 44 controlling gas flow to a pilot jet 45 which will be located adjacent a spark ignition device (not shown) controlled electronic circuitry 46 on a PCB/Printed Circuit Board 46' . A thermocouple 47 acts as a flame sensor and when heated sends signals via a splitter 48 to hold open the valve 41 and allow gas to flow to the pilot 45 and also to the main burner (not shown) in the direction of arrow 48 preferably via a thermostatic valve 49 if valve 42 is open.

Valve 41 is a standard flame failure valve which is connected to be held open as long as a signal comes from thermocouple 47 or until the signal is interrupted by breaking the circuit with an "off" switch 50 which is preferably biassed into the close position since momentary interruption of the signal for the thermocouple 47 will release valve 41 which then shuts off the gas supply to the appliance by closure 41' being biassed onto seat 41'' (as shown in Fig. 4).

A push-member 51 has two parallel actuator arms 52, 53 linearly displaceable therewith as arm 52 is larger than arm 53 since on depression of push member 51 (manually or by foot of a user) or otherwise e.g. by actuation of a solenoid acting on member 51 (possibly via an infra-red futra service remote control device) arm 52 will open valve 41 and at the same time close a switch 54 on the control circuit 46 which will initiate sparking of a sparking device 55 and also energise a power supply circuit 56 and time delay cut-off circuit of the control device 46 to hold valve 41 open for a predetermined time (say 15 seconds) whereupon the valve 41 will close unless a signal is being generated by the thermocouple to keep valve 41 open.

Splitter 48 and the control ensures there is no interruption in the hold-open signal to valve 41 when the time delay circuit transfers control of valve 41 to the thermocouple signal. Thus the operational concept of Fig. 4 so far is similar to that of Figs. 1A - lC.

The significant and inventive development in Fig. 4 is the provision of a normally open gas Mag-valve 42 not hitherto known and which is spring-biassed (or otherwise) into the open position as shown permitting gas to flow through passage 57 to passage 58 and on to the main burner.

The valve 42 is closable by arm 53 being depressed via member 51 and thereupon the control circuit 46 is also energised via switch 54 to send a signal via circuit 59 on splitter 60 to an electro-magnetic part 60 of the valve 42 to hold the valve 42 closed with closure valve 42' against seat 42'' for as long as the time delay cut-off circuit operates. Thus, when the predetermined period of the time delay circuit expires, if the appliance is functioning properly and there is a proper gas supply, the pilot flame at the pilot jet 55 should have ignited and thus if this has occurred on ceasing to energise the electromagnet 42' of valve 42, the valve closure member 42' will be released into the open position thereby allowing gas to flow to the main gas burner and be ignited by the pilot flame. The splitter 60 is provided for It will be appreciated that a relatively quick and simple r- session and release of actuator member 51 (without -nificant hold-down with delay) or ignition as such a place valve 41 in its held open position and valve n its held closed position and energise the con circuit to hold them there for a predetermined period and initiate sparking, the ignition of the appliance is effected in safe, simple and economic manner. Valve 41 can be a standard Mag-valve as exists already and new valve 42 is one which can be simply and economically manufactured. Hitherto expensive tapered plug valves can be avoided. The embodiment has the advantage that it can be operated by a battery electric power supply, if desired, which has considerable economic advantages. Such battery or batteries can be rechargeable by a thermocouple as mentioned previously.

Whilst not specifically illustrated it is envisaged that the member 51 may have an extension which is coupled to the control of a thermostat 49 which controls the height of flame at the main gas burner and thus in addition to timer displacement of member 51 to effect an automatic ignition operation, rotation thereof can control the thermostatic valve 49 and temperature control of the appliance. Alternatively, a thermistor control circuit might be used instead of the thermostatic valve.

The embodiment of Fig. 4 has the added advantage that in the event of a power failure (for whatever reason) normal operation of ignition is still possible with the user holding down member 51 for a period and lighting the pilot with independent flame/spark means until the pilot flame or thermocouple 47 generates a signal to hold open valve 41 whereupon valve 42 is released to open and enable the gas burner to be fuelled and ignite.

As mentioned previously, it should be understood to be within the scope of the invention that instead of electro-magnetic holding of the valve 41 and/or valve 42 in there open and/or closed positions respectively, other means such as mechanical delay means may be used.

Claims (23)

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1. A control system of or for a gas heating appliance comprises a first flame failure valve which requires the application of operator initiatable force (directly or via remote control means) on a displacing means thereof to open the valve and which may thereafter be maintained open by a "flame present" signal from a flame sensor, and a flame sensor to be associated with a pilot light jet and/or associated with a main gas burner of the appliance which is operatively connected to the flame failure valve to maintain such open only when a flame is present, and an electronic spark ignition circuit actuable/energisable upon the application of said force (such as by operation of said displacing means by the operator to cause movement into the open position of the flame failure valve to initiate spark ignition) characterised by the feature that a time delay cut-off means is connected to the flame failure valve and actuable also by the displacement of the displacing means, so that said time delay cut-off holds the flame failure valve open for a predetermined time.

2. A control system as claimed in claim 1, which includes a second flame failure valve located downstream thereof between the first mentioned flame failure valve and the main burner, with said second valve being biassed to be normally closed and openable on the sensing of ignition of the pilot light jet to allow gas flow to the burner.

3. A control system as claimed in claim 1, which includes a second valve located downstream thereof between the first mentioned flame failure valve and the main burner, with said second valve being biassed to be normally open to allow gas flow to the burner and being also displaceable by displacing means into its closed position.

4. A control system as claimed in claim 3, in which time delay means are provided to hold said second valve in its normally closed position for a predetermined time or until released by a flame present signal from a sensor adjacent the pilot flame and/or burner flame.

5. A control system of or for a gas heating appliance comprises an electro-magnetic valve or "Mag-valve" or other first valve, which comprises a flame failure valve of the type which requires the application of the external action of an operator/user on a push or displaceable member thereof to open it but which may thereafter be maintained open by a "flame present" signal from a flame sensor, and a flame sensor associated with a pilot light jet and/or associated with a main gas burner of the appliance which is electrically connected to the magnetic-valve to maintain such open only when a flame is present, and an electronic spark ignition circuit actuable/erergisable upon the pushing of said push or displaceable member by the operator into the open position of the magnetic-valve to initiate spark ignition, characterised by the feature that a power supply circuit with time delay cut-off is connected to the electro-magnetic valve and energisable also by the pushing of the push or displaceable member by a user or otherwise displacing the push or displaceable member so that said supply circuit with time delay cut-off holds the electromagnetic valve open for a predetermined time.

6. A control system as claimed in claim 5, when incorporated in a heating appliance, wherein the heating appliance defined above maintains the magnetic-valve in the open position for a predetermined period to permit pilot gas ignition by the electronic ignition means and which is de-energised after a predetermined period whereupon if no current is flowing from the flame sensor, the magneticvalve automatically cuts off the gas supply in the event of failure of ignition.

7. A control system as claimed in claim 5 or 6, in which first mentioned magnetic-valve when de-energised automatically closes and is located in the gas inlet pipe or duct leading to a pilot light jet and/or the main gas burner and when closed cuts off the gas supply.

8. A control system as claimed in any of claims 1 to 7, in which the main control of the gas flow for the heating appliance comprises a variable flow valve which is in gas series with the magnetic-valve.

9. A control system as claimed in claim 8, in which the main control valve is a rotary valve requiring rotary control or is an integral structure with the magneticvalve.

10. A control system as claimed in claim 9, wherein when the control valve is a rotary valve, and in which an ignition micro switch energises the electronic spark ignition system.

11. A control system as claimed in claim 10, in which the micro switch also energises the electro-magnet of the electro-magnetic valve for a predetermined period and, with successful ignition, the magnetic-valve is maintained open as a result of current flowing from a temperature probe.

12. A control system as claimed in claim 11, in which the temperature probe is a thermocouple located adjacent the gas burner or adjacent a pilot light jet.

13. A control system as claimed in claim 11 or 12, in which the temperature probe is associated with a pilot light jet and the push member of the magnetic-valve or associated displacement means or member therefor is coupled/linked to control the variable flow valve and the displacement means or member is biased to move in a direction slightly away from the push member when released1 and with said variable flow valve being such that when the displacement member is operatively displaced to open the magnetic-valve, the variable flow valve is in a position where no gas flows to the main gas burner but gas does flow to the pilot light jet, and such that on release of the displacement member it is displaced under the action of the biasing means to a position where it also causes the variable flow valve to move into an open setting position and, preferably, its lowest setting position, so that during the sparking ignition, gas is controlled so as to only flow to the pilot light jet and not to the main gas burner.

14. A control system as claimed in any of claims 5 to 13, in which the flame failure device/valve is held open for a predetermined period by an electronic time delay circuit, or a mechanical latching means/device and delayed time release device, or any other suitable retaining and time delay release device.

15. A control system as claimed in any of claims 1 to 14, in which the flame sensor is a thermocouple located adjacent the pilot and/or main gas burner or thermocouple other devices a temperature sensing thermostat or cut-out (TTB) or other device.

16. A control system as claimed in any of claims 1 to 15, in which the electronic spark ignition is controlled to or such as to operate for a predetermined period, or is of the "spark re-ignition" type system which continues sparking until a heat sensor determines ignition has taken place and then de-energises the ignition circuit.

17. A control system as claimed in any of claims 5 to 16, including a second valve located downstream of the first valve between the first mentioned valve and the main burner, with said second valve being biassed to be normally open to allow gas flow to the burner and being also displaceable by said push or displaceable member into its closed position.

18. A control system as claimed in claim 17, in which time delay means are provided to hold said second valve in its normally closed position for a predetermined time or until released by a flame present signal from a sensor adjacent the pilot flame and/or burner flame.

19. A gas heating or other gas fired appliance whenever incorporating the control system as claimed in any of claims 1 to 18.

20. A gas heating appliance including an ignition control system including a normally closed flame failure valve, a normally open valve upstream of the main gas burner of the appliance and downstream of said flame failure device, and which enables gas to normally flow to the burner, and wherein said normally open gas valve is such as to be capable of being held closed during ignition.

21. A gas valve for use in a gas appliance wherein the valve closure member of the valve is biassed into a normally open position and wherein holding means are provided to hold the valve closure member in the closed position for a predetermined time or for as long as said holding means are energised.

22. A valve as claimed in claim 21, in which the holding means is a mechanical timed release device or an electro-magnet, and the valve operates with the action of a magnetic-valve.

23. A control system substantially as herein described with reference to the accompanying drawings.