GB2313650A

GB2313650A - Thermocouple bypass

Info

Publication number: GB2313650A
Application number: GB9621306A
Authority: GB
Inventors: George Josif
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-10-11
Filing date: 1996-10-11
Publication date: 1997-12-03
Anticipated expiration: 2016-10-11
Also published as: GB2313650B; GB9621306D0

Abstract

At start-up knob 4 is depressed to lift valve disc 9 from seat 8 to allow gas to flow from a conduit 1 to an appliance via outlet 16. Upon release of the knob the valve is held open by an electromagnet since a timing unit 25 applies a current to a coil 13 of the electromagnet. The timing unit applies a current for a predetermined period of time. If the thermocouple is heated sufficiently during the time period it will provide sufficient current to coil 13 to retain the valve in the open position when the timed current is released. The timer supplies a current which is sufficient to hold the valve open but which is not sufficient to move the valve from the closed to the open position.

Description

"A thermocouple bypass system" THIS INVENTION relates to a thermocouple bypass system and more particularly to a thermocouple bypass system for use in gas heaters or the like which do not include a pilot light.

Typically, the gas supply for a gas heater is regulated by a thermocouple. Indeed, various Standards Regulations require the use of thermocouples so as to provide a safety cut-off to prevent gas escaping should a gas flame be extinguished.

A heated thermocouple provides an electric current to the coil of an electromagnet to energise the electromagnet. The electromagnet is operable to retain a spring biased plunger which is biased to close a valve seat between the gas supply and an outlet port of a gas tap. In the case of gas heaters with pilot lights such as in domestic boiler systems and the like, the thermocouple maintains the plunger in an open condition to provide a supply of gas through the gas tap. However, as soon as the temperature of the thermocouple drops below a predetermined temperature, i.e. the thermocouple is no longer being heated, the electric current which energises the electromagnet drops and becomes insufficient to hold the plunger against the force of the biassing spring. The force of the spring pushes the plunger back to close the valve seat thereby safely cutting off the gas supply from the outlet port.

In some applications, it is convenient not to use a pilot light. Such applications include domestic gas heaters, radiant heaters, gas heaters for cooking purposes and gas burners for the kebab industry.

Some radiant gas heaters have a single gas supply which provides gas to a number of gas taps which are each connected to a separate heating panel. Since such a system has no pilot light, to ignite all of the heating panels, it is necessary to push in the ON/OFF knob of the respective gas tap to push back the valve disc from the valve seat manually to allow a flow of gas from the gas supply conduit, through the gas tap and out of the outlet port.

The gas supply can then be ignited to heat the heating panel as well as a thermocouple associated with that gas tap. The ON/OFF knob must be kept pressed in until such time as the thermocouple has reached a predetermined temperature at which the current produced by the thermocouple is sufficient to energise the electromagnet and hold back the plunger against the force of the return spring. This is usually for a period of 10 to 15 seconds.

After this time, the ON/OFF knob can be released. The plunger is retained by the electromagnet, energised by the thermocouple current, thereby keeping the gas supply to the heating panel open.

It is extremely inconvenient and time consuming to turn on and ignite each of, for example, five gas taps, individually, one after the other. Accordingly, it is an object of the present invention to provide a thermocouple bypass system which solves the above-mentioned problem and does not suffer from the above-mentioned disadvantages.

Accordingly, one aspect of the present invention provides a thermocouple bypass system for a gas supply, which system comprises a timer unit connected to a current source and operable to provide a current from said current source to energise an electromagnet for a predetermined time to hold open a valve of a regulator unit fed by a gas supply thereby providing a supply of gas from the regulator unit for the predetermined time.

Another aspect of the present invention provides a method of bypassing a thermocouple in a gas supply system having a valve for controlling said supply of gas and a thermocouple for producing an energising current, when heated to a predeterminded temperature, to energise an electromagnet for holding open said valve, which method comprises the steps of: providing a current source for a predetermined time; energising the electromagnet with the current source; and manually opening the valve, the opened valve being held open by the energised electromagnet for the predetermined time thereby providing a supply of gas for the predetermined time.

In order that the present invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: FIG. 1 is a schematic representation of a gas tap incorporating a thermocouple bypass system embodying the present invention, parts of the gas tap and thermocouple bypass system being shown in cross-section, the valve of the system being shown in an open position; and FIG. 2 is a schematic circuit diagram of a thermocouple bypass system embodying the present invention for use with a plurality of gas taps.

Referring to Figure 1, a gas supply conduit 1 provides a flow of gas. A gas tap 2 is secured to the gas supply conduit 1, an inlet port 3 of the gas tap 2 being aligned with a corresponding aperture in the gas supply conduit 1 to allow a flow of gas from the gas supply conduit 1, through the inlet port 3 into the gas tap 2.

The gas tap 2 is provided with an ON/OFF knob 4 which acts as a tap to control the flow rate of gas through the inlet port 3 into the gas tap 2. The gas tap 2 has an outlet 5 which connects with an inlet 6 of a regulator unit 7. The inlet 6 includes a valve seat 8 which is closable by a valve disc 9 carried on a spring biased plunger 10. The plunger 10 is biased such that the value disc 9 closes the valve seat 8. The plunger 10 is biased by a helical spring 11 surrounding the plunger 10. The plunger 10 is slidable along the regulator unit 7 in a direction towards or away from the valve seat 8. The movement of the plunger 10 is limited away from the valve seat 8 by an electromagnet 12.

The electromagnet has an electromagnet coil 13 which can be energised by the current from a thermocouple 14.

The ON/OFF knob 4 is provided with a push rod 15 which passes through the gas tap 2 and partially through the outlet 5 so as to be able to contact the valve disc 9 of the plunger 10 when in its closed position. If the ON/OFF knob 4 is pushed, then the push rod 15 pushes against the valve disc 9 of the plunger 10 and pushes the plunger 10 back into the regulator unit 7 thus opening the valve seat 8 to allow gas to flow from the gas tap 2 into the regulator unit 7 and out of an outlet port 16 of the regulator unit. A gas heater (not shown) or other gas appliance can be connected to the outlet port 16 of the regulator unit 7.

An interruptor block 17 comprising an earthed outer shell 18 and a central conductive core 19 is screwed into the rear of the regulator unit 7 such that the central conductive core 19 is in electrical contact with the electromagnet coil 13 in the regulator unit 7. A terminal lead 20 is held in the interruptor block 17 and makes electric contact with the central conductive core 19. The cathode and anode of the thermocouple 14 are also connected to the interruptor block 17. The cathode 21 of the thermocouple 14 is electrically connected to the outer shell 18 of the interruptor block 17 and the anode 22 of the thermocouple 14 is electrically connected to the central conductive core 19 of the interruptor block 17.

Thus, the thermocouple 14 is electrically connected, via the terminal lead 20 to the electromagnet coil 13.

The probe end 23 of the thermocouple 14 is located remote from the interruptor block 17 and adjacent, for example, a respective heating panel (not shown) of a gas heater, so as to be heated thereby.

The above described system can operate in exactly the same manner as a conventional thermocouple regulated gas tap. However, in accordance with the present invention, a thermocouple bypass system is provided to allow the effect of the thermocouple to be bypassed.

The terminal lead 20 in the interruptor block 17 is connected to an outlet terminal 24 of a timer unit 25. The output terminal 24 can be connected to a number of terminal leads 20 in respective bypass systems although only one is illustrated in Figure 1. A number of terminal leads 200, 20', 20" ...20" are shown connected to the output terminal 24 of Figure 2. The timer unit 25 is connected to a power source 26 such as a battery, mains transformer or the like.

A switch 27 is connected in series between the timer unit 25 and the power source 26. The positive terminal of the power source 26 is earthed.

In operation, the closure of switch 27 starts the timer unit 25 which provides a negative current supply on its output terminal 24 to the terminal lead 20. Since the terminal lead 20 is connected via the central conductive core 19 of the interruptor block 17 to the electromagnet coil 13, the electromagnet coil energises the electromagnet 12. The negative current provided at the output terminal 24 is sufficient to hold the plunger 10 against the force of the spring 11 once the plunger 10 has been bought into contact with the electromagnet 12. However, the current is insufficient to pull the plunger 10 back from the valve seat in its closed position toward the electromagnet 12.

The timer unit 25 is operable to provide the current supply at its output terminal 24 for a predetermined length of time. This length of time can be pre-set during the manufacture of the timer unit and is adjustable at the point of manufacture. However, preferably, the pre-set time cannot be altered by a user.

It has been found that a convenient pre-set time is approximately 20 seconds.

As previously mentioned, once the electromagnet 12 has been energised by the closing of switch 27, the electromagnet 12 will remain energised during the pre-set time, 20 seconds. Once the switch 27 has been closed, the user then pushes in the ON/OFF knob 4 to cause the push rod 15 to push against the plunger 10 and force the plunger 10 back in contact with the electromagnet 12. The ON/OFF knob 4 can also be turned at the same time as pushing it in to a desired heat setting. The plunger 10 is retained by the electromagnet 12 and gas flows from the gas supply conduit 1, through the gas tap 2, through the outlet 5 and inlet 6 into the regulator unit 7 and out of the outlet port 16 to the heating panel. The gas at the heating panel is ignited and begins to heat up the probe end 23 of the thermocouple 14. The ON/OFF knob can be immediately released since the plunger 10 is now being retained in an open position by the electromagnet 12 thereby maintaining the flow of gas out of the outlet port 16. Thus, the user is free to turn on any other taps 2 which may be connected to the gas supply conduit 1 in a similar manner. All the other gas taps 2 in the same system are fed by other output terminals 24 from the same timer unit 25.

Once the pre-set time has elapsed, the timer unit 25 removes the current supply from the output terminals 24.

Thus, the terminal lead 20 is no longer causing the electromagnet 12 to be energised. However, by this time the probe end 23 of the thermocouple will have been adequately heated by the heating panel and will itself be generating a sufficient current to energise the electromagnet 12. As previously described, the anode 22 of the thermocouple 14 is electrically connected to the electromagnet coil 13 via the terminal lead 20 and the central conductive core 19 of the interruptor block 17.

Thus, although current is no longer being supplied by the output terminal 24, current is now being supplied by the thermocouple 14 thereby retaining the plunger 10 and keeping the valve seat 8 open to allow the supply of gas out of the outlet port 16.

The use of the thermocouple bypass system means that a user does not need to hold in each ON/OFF knob 4 of a series of gas taps 2 for the time taken (approximately 10-15 seconds) for each thermocouple 14 to heat up to a high enough temperature to provide a sufficient current to energise the electromagnet 12. This leaves the user free to turn on a number of gas taps connected to the thermocouple bypass system to allow all the gas taps to be turned on in quick succession. As shown in Figure 2, it is necessary to ensure that the output terminal 24 are independent of one another to prevent any cross-feeding of current between a series of thermocouples 14.

It is apparent that the use of the thermocouple bypass system renders pilot lights redundant for the purpose of heating a thermocouple.

The thermocouple bypass system is entirely failsafe in that should there be any power failure or the like, then no current supply will be provided at the output terminal 24 thereby closing the valve seat 8 unless the electromagnet 12 is being energised independently by the thermocouple 14.

Although the system has been described using a separate timer unit 25 and switch 27, it is envisaged that a timer switch can be used, which timer switch remains closed for a pre-set time to allow current to be provided on an output terminal 24 of the timer switch to respective electromagnet coils 13.

Claims

1. A thermocouple bypass system for a gas supply, which system comprises a timer unit connected to a current source and operable to provide a current from said current source to energise an electromagnet for a predetermined time to hold open a valve of a regulator unit fed by a gas supply thereby providing a supply of gas from the regulator unit for the predetermined time.

2. A thermocouple bypass system according to Claim 1, wherein an interruptor block is located between and electrically connected to a thermocouple and the regulator unit, the current source being provided by an output terminal of the timer unit electrical connected by a terminal lead to a part of the interruptor block.

3. A thermocouple bypass system according to Claim 2, wherein the terminal lead is electrically connected to an electromagnet coil of the electromagnet and to a thermocouple.

4. A thermocouple bypass system according to Claim 3, wherein the thermocouple is operable to produce a current sufficient to energise the electromagnet once heated to a predetermined temperature.

5. A thermocouple bypass system according to any preceding claim, wherein a plunger is provided which is moveable from a closed position in which the valve is closed to an open position in which the valve is open, the plunger being biassed into the closed position.

6. A thermocouple bypass system according to Claim 5, wherein the current supplied by the timer unit to the electromagnet is sufficient to retain the plunger in the open position but is insufficient to move the plunger from the closed position to the open position.

7. A thermocouple bypass system according to Claim 5 or 6, wherein a gas tap is provided having an inlet for connection to the gas supply and an outlet for connection to the valve of the regulator unit, the gas tap having a push rod which is operable to engage the plunger and to move the plunger from the closed position to the open position.

8. A thermocouple bypass system according to Claim 7, wherein the gas tap has an ON/OFF knob connected to the push rod to control the flow rate of gas through the tap.

9. A gas supply system incorporating one or more thermocouple bypass systems according to any preceding claim.

10. A gas heater incorporating one or more thermocouple bypass systems according to any one of Claims 1 to 8.

11. A method of bypassing a thermocouple in a gas supply system having a valve for controlling said supply of gas and a thermocouple for producing an energising current, when heated to a predeterminded temperature, to energise an electromagnet for holding open said valve, which method comprises the steps of: providing a current source for a predetermined time; energising the electromagnet with the current source; and manually opening the valve, the opened valve being held open by the energised electromagnet for the predetermined time thereby providing a supply of gas for the predetermined time.

12. A method according to Claim 11, wherein the step of manually opening the valve comprises the step of moving a plunger from a closed position in which the valve is closed to an open position in which the valve is open, the plunger being biassed into the closed position.

13. A method according to Claim 12, wherein the plunger is moved from the closed position to the open position by a push rod which is engagable with the plunger to move the plunger toward the electromagnet.

14. A method according to any one of Claims 11 to 13, wherein the electromagnet is energised by a current supplied by a timer unit.

15. A method according to Claim 14, wherein the current supplied by the timer unit is sufficient to retain the plunger in the open position but is insufficient to move the plunger from the closed position to the open position.

16. A method of bypassing a thermocouple in a gas supply system substantially as hereinbefore described with reference to the accompanying Figures.

16. A thermocouple bypass system substantially as hereinbefore described with reference to and as shown in the accompanying Figures.

17. A method of bypassing a thermocouple in a gas supply system substantially as hereinbefore described with reference to the accompanying Figures.

18. Any novel feature or combination of features disclosed herein.

Amendments to the claims have been fled as follows CLAIMS 1. A thermocouple bypass system for a gas supply, which system comprises a timer unit connected to a current source and operable to provide a current from said current source to energise an electromagnet for a predetermined time to hold open a valve of a regulator unit fed by the gas supply in use thereby providing a supply of gas from the regulator unit for the predetermined time, an interruptor block being located between and electrically connected to the thermocouple and the regulator unit, the current source being provided by an output terminal of the timer unit electrically connected by a terminal lead to a part of the interruptor block.

2. A thermocouple bypass system according to Claim 1, wherein the terminal lead is electrically connected to an electromagnet coil of the electromagnet and to the thermocouple.

3. A thermocouple bypass system according to Claim 2, wherein the thermocouple is operable to produce a current sufficient to energise the electromagnet once heated to a predetermined temperature.

4. A thermocouple bypass system according to any preceding claim, wherein a plunger is provided which is moveable from a closed position in which the valve is closed to an open position in which the valve is open, the plunger being biassed into the closed position.

5. A thermocouple bypass system according to Claim 4, wherein the current supplied by the timer unit to the electromagnet is sufficient to retain the plunger in the open position but is insufficient to move the plunger from the closed position to the open position.

6. A thermocouple bypass system according to Claim 4, or 5, wherein a gas tap is provided having an inlet for connection to the gas supply and an outlet for connection to the valve of the regulator unit, the gas tap having a push rod which is operable to engage the plunger and to move the plunger from the closed position to the open position.

7. A thermocouple bypass system according to Claim 6, wherein the gas tap has an ON/OFF knob connected to the push rod to control the flow rate of gas through the tap.

8. A gas supply system incorporating one or more thermocouple bypass systems according to any preceding claim.

9. A gas heater incorporating one or more thermocouple bypass systems according to any one of Claims 1 to 7.

10. A method of bypassing a thermocouple in a gas supply system having a regulator unit incorporating a valve for controlling said supply of gas and a thermocouple for producing an energising current, when heated to a predeterminded temperature, to energise an electromagnet for holding open said valve, which method comprises the steps of: locating an interruptor block between and electrically connected to the thermocouple and the regulator unit; providing a current source from an output terminal of a timer unit electriclaly connected by a terminal lead to apart of the interruptor block for a predetermined time; energising the electromagnet with the current source; and manually opening the valve, the opened valve being held open by the energised electromagnet for the predetermined time thereby providing a supply of gas for the predetermined time.

11. A method according to Claim 10, wherein the step of manually opening the valve comprises the step of moving a plunger from a closed position in which the valve is closed to an open position in which the valve is open, the plunger being biassed into the closed position.

12. A method according to Claim 11, wherein the plunger is moved from the closed position to the open position by a push rod which is engagable with the plunger to move the plunger toward the electromagnet.

13. A method according to any one of Claims 10 to 12, wherein the electromagnet is energised by a current source supplied by a timer unit.

14. A method according to Claim 13, wherein the current supplied by the timer unit is sufficient to retain the plunger in the open position but is insufficient to move the plunger from the closed position to the open position.

15. A thermocouple bypass system substantially as hereinbefore described with reference to and as shown in the accompanying Figures.