IES20010908A2

IES20010908A2 - An operating mechanism for sequentially operating a fuel gas valve and an ignition means of a gas powered appliance, and a gas powered appliance incorporating the operating mechanism

Info

Publication number: IES20010908A2
Application number: IE20010908A
Authority: IE
Inventors: Alfred Peter Oglesby; John Paul Oglesby; John Joseph Storey
Original assignee: Oglesby & Butler Res & Dev Ltd
Priority date: 2000-10-16
Filing date: 2001-10-16
Publication date: 2002-06-12
Also published as: US20040029060A1; EP1327105A1; WO2002033319A1; AU2001295844A1

Abstract

A hot melt glue gun comprising a main housing (5) having a glue stick accommodating bore (8) extending there through and terminating in a dispensing nozzle (9) through which melted glue is dispensed. A catalytic combustion element (16) is located in a combustion chamber (15) for raising the temperature of the main housing (5) to an appropriate temperature for melting the glue stick. Fuel gas is supplied to the catalytic combustion element (16) through a fuel gas valve (20) having a spindle (40) extending there from. A piezo electric ignition unit (27) generates an EMF for generating a spark across a pair of electrodes (25) in the combustion chamber (15) for igniting the fuel gas to initially burn with flame combustion to raise the temperature of the catalytic element (16) to its ignition temperature. An operating member (51) and an integral camming member (52) are slide able in the direction of the arrow D from an inoperative state to an operative state for sequentially operating the fuel gas valve (20) from a closed to an open state, and then the piezo electric ignition unit (27) for igniting the fuel gas in the combustion chamber (15). An idle camming surface (55) of the camming member (52) engages a cam follower (53) of the spindle (40) of the fuel gas valve (20) with the fuel gas valve (20) in the closed state, and an operating camming surface (59) engages the cam follower (53) with the fuel gas valve (20) in the open state. <Figures 1 & 4>

Description

The present invention relates to an operating mechanism for sequentially operating a fuel gas valve for delivering fuel gas to a gas burner of a gas powered appliance, and an ignition means for igniting the fuel gas at the gas burner, and the invention also relates to a gas powered appliance incorporating the operating mechanism.

Gas powered appliances, for example, gas powered glue guns, soldering irons, hair dryers, curling tongs, sandwich makers and the like, and indeed, gas cookers require the gas supplied to the burner to be ignited before combustion or other forms of conversion of the gas to heat can take place. Gas powered appliances can be broadly divided into two categories, those which convert fuel gas to heat by flame combustion, and those which convert fuel gas to heat by a catalytic reaction of a catalytic combustion element. In the latter type of gas powered appliance, the catalytic combustion element must first be raised to its ignition temperature before the catalytic action can commence whereby the fuel gas is converted to heat.

Various techniques are known for raising a catalytic combustion element to its ignition temperature, for example, it is known to raise the temperature of the catalytic combustion element by an electrically powered heating element, although more * commonly the gas catalytic combustion element is raised to its ignition temperature by initially igniting the fuel gas to burn with a flame which in turn raises the catalytic combustion element to its ignition temperature. On the catalytic combustion element reaching its ignition temperature the flame is extinguished. Extinguishing of the flame may be automatic, or may be carried out by momentarily interrupting the flow of fuel gas to the catalytic combustion element.

PCT Specification No. PCT-A-WO 97/38265 of Oglesby, et al discloses a gas powered soldering iron in which a soldering tip of the lering iron is heated by a mbustion chamber OPEN TO PUBLIC INSPECTION UNDER SECTION 28 AND RULE 23 VA June JNL No. Of 090g adjacent the soldering tip. The catalytic combustion element is initially raised to its ignition temperature by igniting the fuel gas to burn with a flame within the catalytic combustion element. As the catalytic combustion element progressively reaches its ignition temperature the fuel gas is converted to heat by catalytic reaction with the catalytic combustion element and the flame is starved of fuel gas, and thus is automatically extinguished.

PCT Specification No. PCT-A-WO 95/02788 also of Oglesby, et al discloses a gas powered soldering iron in which a soldering tip of the soldering iron is heated by a gas catalytic combustion element located in a combustion chamber adjacent the soldering tip. The gas catalytic combustion element is initially raised to its ignition temperature by flame combustion whereby the fuel gas is burnt in the combustion chamber in a flame for raising the temperature of the gas catalytic combustion element to its ignition temperature. On the gas catalytic combustion element reaching its ignition temperature the flame is extinguished by momentarily interrupting the fuel gas supply to the flame.

In the soldering irons disclosed in the two PCT specifications Nos. PCT-A-WO 97/38265 and PCT-A-WO 95/02788 a piezo electric ignition unit is provided for generating an EMF which is applied across a spark gap defined by a pair of electrodes in the combustion chamber for igniting the fuel gas to initially burn with a flame. The fuel gas is supplied to the combustion chamber through a fuel gas valve. Operating mechanisms are provided for operating the fuel gas valve and the piezo electric ignition unit so that an adequate supply of fuel gas has been delivered to the combustion chamber before a spark is generated for igniting the fuel gas.

Otherwise, if the timing of the spark was such that the spark was generated before there was an adequate supply of fuel gas in the combustion chamber, the spark would fail to ignite the fuel gas to burn with a flame.

While the operating mechanisms disclosed in the two PCT specifications Nos. PCTA-WO 97/38265 and PCT-A-WO 95/02788 facilitate sequential operation of the fuel gas valve and the ignition unit, nonetheless, there is a need for an improved IE 0 1 09 0 8 operating mechanism for sequentially operating a fuel gas valve and an ignition means for sequentially supplying fuel gas and igniting the fuel gas in a gas burner.

The present invention is directed towards providing such an operating mechanism, and the invention is also directed towards a gas powered appliance incorporating the operating mechanism.

According to the invention there is provided an operating mechanism for sequentially operating a fuel gas valve for delivering fuel gas to a fuel gas burner and an ignition means for igniting the fuel gas at the burner, wherein the operating mechanism comprises a camming member moveable between an inoperative state and an operative state, a cam follower co-operable with the camming member and with the fuel gas valve for operating the fuel gas valve from a closed state isolating the gas burner from the fuel gas, to an open state for delivering fuel gas to the gas burner in response to the camming member being moved from the inoperative state to the operative state, and an activating member associated with the camming member and being co-operable with the ignition means and being moveable with the camming member for operating the ignition means when the camming member is in the operative state sequentially after the fuel gas valve has been operated into the open state, for igniting the fuel gas at the gas burner.

Preferably, the camming member is moveable in the operative state after the fuel gas valve has been operated into the open state for subsequently operating the ignition means.

Advantageously, the camming member defines an activating camming surface for co-operating with the cam follower for operating the fuel gas valve between the closed state and the open state.

Preferably, the camming member defines an operating camming surface for cooperating with the cam follower for retaining the fuel gas valve in the open state. ΙΕ018918 In one embodiment of the invention the operating camming surface is an elongated surface for facilitating further movement of the camming member in the operative state for operating the ignition means after the fuel gas valve has been operated into its open state, and preferably, the activating member co-operates with the ignition means for operating the ignition means during the further movement of the camming member and the activating means when the camming member is in the operative state.

In another embodiment of the invention the camming member defines a detent between the activating camming surface and the operating camming surface for releasably retaining the cam follower in engagement with the operating camming surface.

In a further embodiment of the invention the camming member is an elongated member, the respective activating and operating camming surfaces being sequentially defined longitudinally along the camming member.

Preferably, the camming member defines an idle camming surface for engaging the cam follower when the camming member is in the inoperative state, and advantageously, the activating camming surface is located between the operating camming surface and the idle camming surface.

Ideally, the respective idle camming surface, the activating camming surface and the operating camming surface define a single continuous camming surface.

Preferably, the camming member and the activating member are moveable in one continuous movement between the inoperative state and the operative state, and in the operative state.

In one embodiment of the invention the camming member and the activating member are moveable from the inoperative state to the operative state, and in the operative state in one single direction, and are moveable from the operative state to ΙΕβ 1 09 Β8 the inoperative state in the reverse direction. Preferably, the camming member and the activating member are moveable between the inoperative state and the operative state, and in the operative state with linear motion. Advantageously, the camming member and the activating member are moveable between the inoperative state and the operative state, and in the operative state with rectilinear motion.

In one embodiment of the invention the camming member and the activating member are carried on an operating member, the operating member being moveable between the inoperative state and the operative state, and in the operating state for in turn moving the camming member and the activating member between the inoperative and operative states, and in the operative state, respectively. Preferably, the operating member, the camming member and the activating member are formed as a single one-piece integral unit.

In one embodiment of the invention the operating member is an elongated member, the camming member extending longitudinally from one end thereof, and the activating member extending transversely from the operating member at the other end thereof. Preferably, the camming member extends contiguously from the operating member.

In another embodiment of the invention a thumb engaging member is provided on the operating member for facilitating urging of the operating member between the inoperative and operative states, and in the operative state for operating the ignition means.

In one embodiment of the invention the activating member is adapted for operating an ignition means provided by a piezo electric ignition unit.

Additionally the invention provides a gas powered appliance comprising a gas burner, a fuel gas valve for supplying fuel gas to the gas burner, and an ignition means for igniting the fuel gas at the fuel gas burner, wherein an operating mechanism according to the invention is provided for sequentially operating the fuel IE 0 1 09 0 8 gas valve and the ignition means for igniting the fuel gas at the gas burner.

Further the invention provides a gas powered appliance comprising a gas burner, a fuel gas valve for supplying fuel gas to the gas burner, and an ignition means for igniting fuel gas at the fuel gas burner, wherein an operating mechanism is provided for sequentially operating the fuel gas valve and the ignition means for igniting the fuel gas at the gas burner, the operating mechanism comprising a camming member moveable between an inoperative state and an operative state, a cam follower cooperable with the camming member and with the fuel gas valve for operating the fuel gas valve from a closed state isolating the gas burner from the fuel gas, to an open state for delivering fuel gas to the gas burner in response to the camming member being moved from the inoperative state to the operative state, and an activating member associated with the camming member and being co-operable with the ignition means and being moveable with the camming member for operating the ignition means when the camming member is in the operative state sequentially after the fuel gas valve has been moved into the open state, for igniting the fuel gas at the gas burner.

In one embodiment of the invention the ignition means is a piezo electric ignition unit comprising a piezo electric crystal for generating an EMF for in turn generating an ignition spark across a pair of electrodes located adjacent the gas burner, and an operating plunger urgeable into the ignition unit for operably engaging the piezo electric crystal for generating the EMF, the activating member being co-operable with the operating plunger for urging the operating plunger into the ignition unit when the camming member and the activating member are in the operative state and are being further moved in the operative state, for in turn generating the EMF.

In another embodiment of the invention the piezo electric ignition unit is located adjacent the operating member and is oriented so that the operating plunger is urgeable into the piezo electric ignition unit in a direction parallel to the direction of movement of the operating member between the inoperative state and the operative state. ΙΕΟ 1 Ο 9 Ο 8 In a further embodiment of the invention the fuel gas valve comprises a valve housing and an operating spindle extending therefrom for operating the fuel gas valve between the closed and the open states, the operating spindle being cooperable with the cam follower and being moveable by the cam follower from the closed state to the open state in response to the camming member being moved from the inoperative state to the operative state.

Preferably, the operating spindle is slideable in the valve housing between the closed and the open states.

Advantageously, the camming member is slideably mounted relative to the valve housing and the cam follower is carried on the operating spindle.

Ideally, the operating spindle extends transversely of and is moveable in a direction transversely of the direction of movement of the camming member between the respective inoperative and operative states.

In one embodiment of the invention the ignition means is carried on a mounting bracket extending from the valve housing of the fuel gas valve.

In another embodiment of the invention the fuel gas burner comprises a combustion chamber having a gas powered catalytic combustion element located therein for converting the fuel gas to heat by flameless catalytic reaction, and a fuel gas nozzle is located adjacent the combustion chamber for delivering fuel gas into the combustion chamber, the fuel gas nozzle being adapted for facilitating initial flame ignition of the fuel gas for raising the temperature of the gas catalytic combustion element to its ignition temperature.

Preferably, the fuel gas nozzle and the gas catalytic combustion element are arranged so that as the gas catalytic combustion element reaches its ignition temperature and commences to convert fuel gas to heat by flameiess combustion, IE 0 1 09 0 8 the flame is starved of fuel gas and extinguished.

In one embodiment of the invention the gas powered appliance is a glue gun.

In another embodiment of the invention the gas powered appliance is a soldering iron.

In a further embodiment of the invention the gas powered appliance is a hair dryer.

In a still further embodiment of the invention the gas powered appliance is a hair curling tongs.

In another embodiment of the invention the gas powered appliance is a sandwich maker.

The advantages of the invention are many. The operating mechanism according to the invention is particularly suitable for use with portable hand held gas powered devices, for example, gas powered tools such as glue guns, soldering irons, hair dryers, sandwich makers and the like, although the operating mechanism is also suitable for non-portable gas powered appliances, for example, domestic gas cookers, ovens and the like. A particular advantage of the invention is that it provides a relatively simple operating mechanism for sequentially operating a fuel gas valve and an ignition means. In particular, the operating mechanism ensures that sufficient fuel gas will be available at the gas burner for ignition by the time the ignition means is operated for igniting the fuel gas. This, thus, avoids unnecessary wastage of gas, which would otherwise occur if the ignition means was operated before sufficient fuel gas was available at the burner, since a number of attempts would be required to ignite the fuel gas, thus leading to leakage and loss of fuel gas before the fuel gas would be successfully ignited.

The invention will be more clearly understood from the following description of a preferred embodiment thereof, which is given by way of example only, with reference IE 0 1 0 9 0 β to the accompanying drawings, in which: Fig. 1 is a partly diagrammatic partly cross-sectional side eievational view of a glue gun according to the invention illustrating an operating mechanism also according to the invention for sequentially operating a fuel gas valve and an ignition device of the glue gun, Fig. 2 is a transverse cross-sectional side eievational view of the operating mechanism of Fig. 1, Fig. 3 is a view similar to Fig. 2 of the operating mechanism of Fig. 2 illustrated in a different position, and Fig. 4 is a view similar to Fig. 2 of the operating mechanism of Fig. 2 illustrated in a further different position.

Referring to the drawings, there is illustrated a gas powered appliance, which in this embodiment of the invention is provided by a portable hand held gas powered hot melt glue gun according to the invention indicated generally by the reference numeral 1. The glue gun 1 comprises a casing 2 of plastics material which forms a main portion 3 and a handle portion 4 extending downwardly from the main portion 3. A main housing 5 of heat conductive material, typically, aluminium is located in the main portion 3 of the casing 2. A glue stick accommodating bore 8 of diameter suitable for receiving a stick of hot melt glue for melting therein extends through the main housing 5, and terminates in a downstream dispensing nozzle 9 through which melted glue is dispensed. An urging mechanism 10 having a stick engaging member 11 for engaging the end of a glue stick is slideably carried in the main housing 5, and is slideable in the direction of the arrow A for urging a glue stick into and through the glue accommodating bore 8 for in turn discharging melted glue through the dispensing nozzle 9. The urging mechanism 10 is slideable in the reverse direction, namely, in the direction of the arrow B for accommodating a fresh glue stick into the glue stick accommodating bore 8. This aspect of hot melt glue ΙΕο 1 Ο 9 08 guns will be well known to those skilled in the art.

A combustion chamber 15 is formed in the main housing 5 for accommodating a hollow cylindrical gas catalytic combustion element 16 for converting fuel gas to heat by catalytic reaction for heating the main housing 5, and in turn for melting a glue stick in the glue stick accommodating bore 8.

A rechargeable fuel gas reservoir 17 located in the handle portion 4 of the casing 2 stores fuel gas in liquid form. A recharging valve 18 in the reservoir 17 facilitates recharging of the reservoir 17 with liquid fuel gas.

A fuel gas valve 20 comprising a valve housing 21 supplies fuel gas from the reservoir 17 to a pressure regulator (not shown) for regulating the pressure and a flow regulator (also not shown) for regulating flow rate of the fuel gas. The pressure and flow regulators are located in a regulator housing 22. A venturi mixer (also not shown) in the regulator housing 22, downstream of the pressure and flow regulators mixes the fuel gas with air, and the fuel gas/air mixture is delivered into the combustion chamber 15 through a fuel gas nozzle 24. The fuel gas jet 24 is located centrally in the catalytic combustion element 16 and adjacent the upstream end thereof. A pair of electrodes 25 in the combustion chamber 15 are spaced apart to form a spark gap across which a spark is generated for initially igniting the fuel gas/air mixture to burn in a flame within a bore 26 of the catalytic combustion element 16 for raising the gas catalytic combustion element 16 to its ignition temperature. The electrodes 25 are located relative to the catalytic combustion element 16 for progressively raising the catalytic combustion element to its ignition temperature, so that as the catalytic combustion element 16 progressively reaches its ignition temperature the flame is progressively starved of fuel gas, and thus is automatically extinguished. The operation of such an arrangement for raising a catalytic combustion element to its ignition temperature and subsequently automatically extinguishing the flame by starving the flame of fuel gas is described in PCT Specification No. PCT-A-WO 97/38265.

An ignition means, in this embodiment of the invention a piezo electric ignition unit 27 is mounted in the main portion 3 of the casing 2 on a mounting bracket 28 which extends upwardly from the valve housing 21 of the fuel gas valve 20. The piezo electric ignition unit 27 is of the type which comprises a piezo electric crystal (not shown), which on having a force applied in one axial direction generates an EMF across a pair of opposite faces which are aligned transversely to the direction in which the force is being applied. A pair of conductors 30 extending from the piezo electric ignition unit 27 apply the EMF to the electrodes 25 for generating the spark across the spark gap. An operating plunger 31 extending into the piezo electric ignition unit 27 is urgeable into the unit 71 in the direction of the arrow C from a reset position, illustrated in Figs. 1 to 3, for applying the force to the piezo electric crystal (not shown) for generating the EMF. A compression spring (not shown) located within the piezo electric ignition unit 27 urges the operating plunger 31 outwardly of the piezo electric ignition unit 27 for returning the operating plunger 31 to the reset position after an EMF has been generated. Such piezo electric ignition units and their operation will be well known to those skilled in the art.

Turning now to the fuel gas valve 20, a sub-housing 35 extends from the valve housing 21 into the reservoir 17, and defines a valving chamber 36. An inlet port 37 in the sub-housing 35 accommodates fuel gas from the reservoir 17 into the valving chamber 36 and forms a valve seat 38 within the valving chamber 36. An elongated spindle 40 extending from and through a hollow interior region 41 formed in the valve housing 21 is slideable in the valve housing 21 in the directions of the arrows F and G for operating the fuel gas valve 20 between a closed and an open state. The spindle 40 carries a valving member 43 which co-operates with the valve seat 38 for selectively closing the inlet port 37 for in turn operating the fuel gas valve 20 in the closed state. A compression spring 44 acting between an upper wall 45 and an annular flange 46 extending around the spindle 40 urges the spindle 40, and in turn the valving member 43 into the closed state with the valving member 43 in sealing engagement with the valve seat 38. An O-ring seal 47 co-operating with the spindle 40 seals the valving chamber 36 from the hollow interior region 41 of the valve housing 21. An O-ring seal 48 in the upper wall 45 of the valve housing 21 co12 operates with the spindle 40 for preventing leakage of fuel gas from the hollow interior region 41 which may inadvertently leak past the O-ring seal 47.

The spindle 40 extends into the regulator housing 22 and is slideable therein. A central fuel gas accommodating bore (not shown) extends centrally through the spindle 40 for accommodating fuel gas from the valving chamber 36 to the pressure regulator (not shown) in the regulator housing 22. A transverse bore 49 extending transversely through the spindle 40 communicates with the central bore (not shown) for accommodating fuel gas into the central bore from the valving chamber 36. The diameter of the spindle 40 in the valving chamber 36 is such as to permit flow of fuel gas from the inlet port 37 between the spindle and the sub-housing up to the transverse bore 49.

An operating mechanism also according to the invention and indicated generally by the reference numeral 50 is located in the casing 2 and extends outwardly therefrom for facilitating sequential operation of the fuel gas valve 20 and the piezo electric ignition unit 27 for supplying fuel gas to the combustion chamber 15 and then for igniting the fuel gas in the combustion chamber 15 to burn with flame combustion for progressively raising the temperature of the catalytic combustion element 16 to its ignition temperature. The operating mechanism 50 comprises an elongated operating member 51 which is moveable with rectilinear motion in the direction of the arrow D from an inoperative state illustrated in Figs. 1 and 2 with the fuel gas valve 20 in the closed state to an operative state illustrated in Figs. 3 and 4 with the fuel gas valve 20 in the open state. The operating member 51 is then further moveable with rectilinear motion in the direction of the arrow D in the operative state for operating the piezo electric ignition unit 27 for generating the EMF for in turn generating a spark between the electrodes 25. A support member 42 extending from the valve housing 21 slideably supports the operating member 51.

An elongated camming member 52 extends longitudinally from and contiguously with the operating member 51 for co-operating with a cam follower 53 secured to a circumferentially extending flange 54 on the spindle 40, for operating the fuel gas ΙΕΟ 1 09 II valve 20 between the closed and the open state. The camming member 52 defines an idle camming surface 55 which is engageabie with the cam follower 53 when the camming member 52 and the operating member 51 are in the inoperative state and the fuel gas valve 20 is in the closed state. An activating camming surface 56 inclines upwardly from the idle camming surface 55 for co-operating with the cam follower 53 for urging the cam follower 53, and in turn the spindle 40 upwardly in the direction of the arrow F for disengaging the valving member 43 from the valve seat 38, for in turn operating the fuel gas valve 20 from the closed state to the open state as the operating member 51 and the camming member 52 are being urged in the direction of the arrow D from the inoperative state towards the operative state. The activating camming surface 56 terminates in a ridge 57, and the camming surface then inclines slightly downwardly at 58 to an elongated camming surface 59 for engaging the cam follower 53 when the camming member 52 and the operating member 51 are in the operative state, for in turn operating the fuel gas valve 20 in the open state. The ridge 57 of the camming member 52 acts as a detent for retaining the cam follower 53 in engagement with the operating camming surface 59 for retaining the fuel gas valve 20 in the open state.

A transversely extending activating member 60 extends transversely from the operating member 51 for engaging the operating plunger 31 of the piezo electric ignition unit 27 when the operating member 51 and the camming member 52 have moved into the operative state with the cam follower 53 engaging the operating camming surface 59 adjacent the ridge 57, see Fig. 3. Thus, further movement of the operating member 51 in the direction of the arrow D causes the activating member 60 to urge the operating plunger 31 into the piezo electric ignition unit 27 for in turn generating the EMF for generating the spark across the electrodes 25, see Fig. 4. A thumb grip 61 is provided on the activating member 60 for facilitating urging of the operating member 51 in the direction of the arrow D from the inoperative to the operative states. The activating member 60 can be gripped for urging the operating member 51 and the camming member 52 in the direction of the arrow E from the operative state to the inoperative state so that the ridge 57 forming the detent passes beneath the cam follower 53, and the cam follower 53 is returned IE01S908 to engage the idle camming surface 55 for closing the fuel gas valve 20.

Once the thumb has been removed from the thumb grip 61, the outward spring urging of the operating plunger 31 returns the operating plunger 31 to the reset position, and also urges the operating member 51 and the camming member 52 in the direction of the arrow E to a normal operating position in the operative state where the cam follower 53 is engaged by the operating camming surface 59 adjacent the ridge 57 for operating the fuel gas valve 20 in the open state, see Fig. 3. The ridge 57 is positioned on the camming member 52 so that when the operating member 51 has been urged in the direction of the arrow D from the inoperative state to the operative state, and the cam follower 45 has engaged the operating camming surface 59, and has just cleared the ridge 57, the operating member 51 is in the normal operating position, and the activating member 60 is just about to engage the operating plunger 31 of the piezo electric ignition unit 27 in its reset position. Thus, further movement of the operating member 51 in the direction of the arrow D in its operative state urges the operating plunger 31 into the piezo electric ignition unit 27 for generating the EMF, for in turn generating the spark across the electrodes 25.

In use, to operate the glue gun 1 a glue stick is inserted into the glue stick accommodating bore 8, and is urged inwardly into the bore 8 in the direction of the arrow A by the urging mechanism 10. The operating mechanism 50 is operated by engaging the thumb grip 61 with a thumb of the user, and urging the operating member 51 in the direction of the arrow D from the inoperative state to the operative state for in turn operating the fuel gas valve 20 from the closed state to the open state. Fuel gas is supplied through the fuel gas valve 20, the pressure and flow regulators and the venturi mixer (none of which are shown) in the regulator housing 22 where it is mixed with air and delivered to the nozzle 24 in the combustion chamber 15. Once the operating member 51 and the camming member 52 have been urged into normal operating position in the operative state, further urging of the operating member 51 in the direction of the arrow D causes the activating member 60 to urge the operating plunger 31 into the piezo electric ignition unit 27 for τ ο 9ββ generating an EMF, and in turn a spark across the electrodes 25, thereby igniting the fuel gas/air mixture to bum with a flame. On release of the operating mechanism 50 by the thumb of the user the operating member 51, and in turn the camming member 52 are urged in the direction of the arrow E to the normal operating position by the operating plunger 31 of the piezo electric ignition unit 27 returning to its reset position. The fuel gas/air mixture burning with a flame causes the temperature of the catalytic combustion element to progressively rise to its ignition temperature, and thus the catalytic combustion element 16 progressively commences to convert fuel gas to heat, and eventually starves the flame of fuel gas, thus extinguishing the flame.

Once the main housing 5 has been brought up to full heat by the catalytic combustion element 16 the glue stick commences to melt towards the nozzle 9. By urging the glue stick into the glue stick accommodating bore 8 by the urging mechanism 10, melted glue adjacent the dispensing nozzle 9 is discharged through the dispensing nozzle 9, and the glue stick commences to progressively melt from the dispensing nozzle 9 in an upstream direction through the glue stick accommodating bore 8. Thus, continuous pressure being applied to the urging mechanism 10 by a thumb of the user continuously discharges glue through the dispensing nozzle 9, When gluing has been completed and it is desired to switch off the glue gun 1, the thumb grip 61 is gripped between a thumb and forefinger of the user, and is urged in the direction of the arrow E from the operative state to the inoperative state, thus passing the ridge 57 beneath the cam follower 53, and returning the camming member 52 to the inoperative state, so that the cam follower 53 is in engagement with the idle camming surface 55. In this state the action of the compression spring 44 on the spindle 40 returns the spindle 40 in the direction of the arrow G to its closed state, thereby operating the fuel gas valve 20 in its closed state.

It is envisaged that in certain cases a specific return means may be provided for returning the operating member and the camming member to the normal operating position instead of relying on the return spring action of the operating plunger of the IF η ι 0 9 0 8 piezo electric ignition unit. Such a return means may, for example, be provided by a compression spring.

It will also be appreciated that while the regulator housing has been described as comprising a pressure and flow regulator, one or both of these may be dispensed with.

It is also envisaged that a thermostatic control mechanism may be provided for maintaining the temperature of the main housing at a predetermined temperature. Such a thermostatic control mechanism would include a temperature sensor located in the main housing 5 which would operate a flow control valve typically located in the regulator housing in response to the temperature sensed by the temperature sensor.

While the reservoir has been described as being a rechargeable reservoir, it will be appreciated that it Is not essential that the reservoir be rechargeable. Indeed, in certain cases, it is envisaged that the handle portion of the casing may be adapted for receiving a disposable reservoir.

While the operating mechanism has been described for use with a glue gun, it will be readily apparent to those skilled in the art that the operating mechanism may be used in any other gas powered tool or appliance, for example, a gas powered soldering iron, a gas powered hair dryer, a gas powered curling tongs, a gas powered sandwich maker, or indeed, a gas powered domestic cooker. It will of course be appreciated that the operating mechanism may be used with a gas powered appliance whether the gas is converted to heat by catalytic combustion or flame combustion.

Claims

1. An operating mechanism for sequentially operating a fuel gas valve (20) for delivering fuel gas to a fuel gas burner (16) and an ignition means (27) for igniting the fuel gas at the burner (16), characterised in that the operating mechanism (50) comprises a camming member (52) moveable between an inoperative state and an operative state, a cam follower (53) co-operable with the camming member (52) and with the fuel gas valve (20) for operating the fuel gas valve (20) from a closed state isolating the gas burner (16) from the fuel gas, to an open state for delivering fuel gas to the gas burner (16) in response to the camming member (52) being moved from the inoperative state to the operative state, and an activating member (60) associated with the camming member (52) and being co-operable with the ignition means (27) and being moveable with the camming member (52) for operating the ignition means (27) when the camming member (52) is in the operative state sequentially after the fuel gas valve (20) has been operated into the open state, for igniting the fuel gas at the gas burner (16).

2. An operating mechanism as claimed in Claim 1 characterised in that the camming member (52) is moveable in the operative state after the fuel gas valve (20) has been operated into the open state for subsequently operating the ignition means (27).

3. An operating mechanism for sequentially operating a fuel gas valve for delivering fuel gas to a fuel gas burner and an ignition means for igniting the fuel gas at the burner, the operating mechanism being substantially as described herein with reference to and as illustrated in the accompanying drawings.

4. A gas powered appliance comprising a gas burner (16), a fuel gas valve (20) for supplying fuel gas to the gas burner (16), and an ignition means (27) for igniting fuel gas at the fuel gas burner (16), characterised in that an operating mechanism (50) is provided for sequentially operating the fuel gas valve (20) and the ignition means (27) for igniting the fuel gas at the gas burner (16), the operating mechanism (50) comprising a camming member (52) moveable between an inoperative state and an operative state, a cam follower (53) co-operable with the camming member (52) and with the fuel gas valve (20) for operating the fuel gas valve (20) from a closed state isolating the gas burner (16) from the fuel gas, to an open state for delivering fuel gas to the gas burner (16) in response to the camming member (52) 5 being moved from the inoperative state to the operative state, and an activating member (60) associated with the camming member (52) and being co-operable with the ignition means (27) and being moveable with the camming member (52) for operating the ignition means (27) when the camming member (52) is in the operative state sequentially after the fuel gas valve (20) has been moved into the open state, 10 for igniting the fuel gas at the gas burner (16).

5. A gas powered appliance substantially as described herein with reference to and as illustrated in the accompanying drawings.