IE20020795A1

IE20020795A1 - Compact stove

Info

Publication number: IE20020795A1
Application number: IE20020795A
Authority: IE
Inventors: Derek Butler
Original assignee: Bs Mfg Ltd
Priority date: 2002-03-28
Filing date: 2002-10-04
Publication date: 2003-10-01
Also published as: EP1348910A1

Abstract

The present invention provides a compact stove that may be used for the warming of food or the like. The stove includes a burner unit that is mounted above a gas fuel reservoir. Control means are provided to effect a control of fuel from the reservoir, through flow means being in fluid communication with both the reservoir and the burner unit, and thereby control the heat generated at the burner unit. The stove further includes heat control means which are adapted to minimise a transfer of heat from the burner unit back towards the gas reservoir. <Figure 1>

Description

FIELD OF THE INVENTION This invention relates to a stove, generally of the catalytic type and often also referred to as a chaffing stove or unit or a bamboree. Of particular interest are portable stoves of the type having a burner to which a compressed gas reservoir is directly attached - the burner being for combustion of the compressed gas. Of special interest is a stove of a type that is easily carried by hand.

Chaffing stoves are primarily used in the cooking areas of restaurants to keep food warm following preparation in the kitchen, before the cooked food is brought to diners. Catalytic stoves of the type to which the present invention is directed are not generally used in the actual dining area. Further applications of the catalytic stove of the invention include use for cooking during outside pursuits, such as hiking, mountaineering, camping, or fishing, as well as therapeutic use and a multiplicity of non-food related functions.

BACKGROUND OF THE INVENTION ΏΡΕΝΤ0 PUBLIC INSPECTION The present invention relates to stoves generally and in particular those stoves of the type which bum gas fuel. Such stoves consist of two main parts - a reservoir which holds the gas fuel, and a burner unit which connects to the reservoir and serves for 25 burning fuel from the reservoir. Stoves of this kind may be portable, for example for use as camping stoves or as chaffing stoves of the type for maintaining cooked food at a temperature suitable for serving for eating. Of particular interest are compact stoves of tjie type that are readily portable. Such stoves often have a burner which is directly O i Attachable to a reservoir of gas. The burner and reservoir together form a self-supporting (ΐ Structure where the burner is arranged above the reservoir in the working orientation of Vot j. rLj tftie device. Normally such stoves do not require any additional support or equipment to ''i |tand upright and operate. In this respect, the stoves of the invention are distinguished $ % IE 0 2 0 7 9 5 from trolleys or tables and the like which may have one or more burners incorporated into a platform or some such other support for the material (normally food/water) to be heated.

There are many limitations associated with conventional stoves. Some suffer from the problem that the burner may easily be extinguished for example by a gust of wind etc. Other limitations include the fact that the vapour pressure in the gas reservoir can substantially fall off due to cooling when the gas expands from its compressed state. This may result in incomplete emptying of the reservoir or reduced amounts of gas being available for combustion. Also disadvantageous is the fact that the gas reservoir is often a disposable one - not designed for ease of re-filling/re-use. Blocking of the burner nozzle may occur due to deposits from heavier hydrocarbons in the gas fuel, while there may be also an inability to regulate the temperature produced by the burner to a desirable extent - in particular to maintain relatively low temperatures such as about 100°C. Further limitations that can occur include the undesirable transmission of heat to parts of the stove proximate the burner, so that for example materials which have high resistance to heat have to be employed.

US Patent No. 4,899,722 (Horewitch) describes a burner assembly for use with a chafing dish of the type supported by legs. The burner is inserted under the chafing dish, which is a large platform supported on legs and covered with a cooking cover or lid. The burner is described as having a unique support structure with a fuel source coupled to the burner head by conduit means of sufficient length to position the fuel source beside the chafing dish.

BRIEF SUMMARY OF THE INVENTION According to a first aspect of the invention, there is provided a stove for maintaining prepared food in a warm state, comprising: (a) a fuel reservoir, (b) a burner unit, (c) flow means communicating between the fuel reservoir and the burner ¢02 0795 unit; and (d) control means for regulating flow of fuel from the fuel reservoir to the burner unit, wherein the fuel reservoir is a gas tank, and means are provided for controlling heat transfer from the region of the burner unit to the interior of the gas tank.

The heat transfer controlling means suitably comprises a heat deflector located between the burner unit and the fuel reservoir. The heat deflector preferably further comprises heat activated deformation means.

Preferably, the burner unit and the flow means are separated by an air gap. The air gap may suitably be linear or circumferential.

In a further aspect, the invention is directed to a stove for maintaining prepared food in a warm state, comprising: (a) a fuel reservoir, (b) a burner unit, (c) flow means communicating between the fuel reservoir and the burner unit; and (d) control means for regulating flow of fuel from the fuel reservoir to the burner unit, wherein the fuel reservoir comprises a reinforcing pillar.

The reinforcing pillar suitably extends between a region of the reservoir in which said control means is incorporated, and a base region of the reservoir.

A gas fill valve may be accommodated in said pillar in the vicinity of the base region of the reservoir, and is preferably positively retained within said pillar. ¢02 07 9 5 A seal may be provided to substantially inhibit discharge of liquid gas through a fill valve air vent passage, during a gas filling operation.

Preferably, the reservoir is substantially cylindrical and the central pillar is centrally located within the reservoir along an axis of symmetry thereof. The reservoir may be a refillable gas tank of less than 250 ml capacity. The diameter of the tank is suitably substantially equal to the height of the stove.

In a further aspect of the invention, there is provided a stove wherein the fuel reservoir comprises a plastics material. The fuel reservoir preferably comprises a twopart structure consisting of a substantially cup-shaped body portion and a closure portion for co-operative sealing association with the body portion.

Interconnection of the closure portion and body portion of the fuel reservoir may effected by screwing together or by a bayonet-type coupling action.

The flow means suitably incorporates heat exchange features.

In any aspect of the invention the flow means preferably comprises a rotary valve assembly and the control means includes a rotary switch for displacement between end positions corresponding to full-flow and shut-off conditions.

In an alternative aspect of the invention, there is provided a stove for maintaining prepared food in a warm state, comprising: (a) a fuel reservoir, (b) a burner unit, (c) flow means communicating between the fuel reservoir and the burner unit; and (d) control means for regulating flow of fuel from the fuel reservoir to the burner unit wherein the burner unit includes at least two catalytic elements. ΙΕΟ2 07 9 5 The stove according to the invention may comprise a multiplicity of catalytic elements arranged one after the other in the direction of gas flow. Suitably, at least one of said catalytic elements has a greater diameter than the diameter of the element immediately preceding it in the direction of gas flow. The burner unit may have a stepped cross-section, each step serving to accommodate a catalytic element and at least one step being of greater diameter than the diameter of the step immediately preceding it in the direction of gas flow. In a stove according to the invention, the fuel reservoir is preferably a gas tank, and means are provided for transferring heat from the region of the burner unit to the interior of the gas tank.

In a second alternative aspect, the invention is directed to a stove for maintaining prepared food in a warm state, comprising: (a) a fuel reservoir, (b) a burner unit, (c) flow means communicating between the fuel reservoir and the burner unit; and (d) control means for regulating flow of fuel from the fuel reservoir to the burner unit, wherein the fuel reservoir is a gas tank, and means are provided for transferring heat from the region of the burner unit to the interior of the gas tank.

At least the burner unit and the flow means are suitably made of metal and a metallic heat transfer element located in the interior of the gas tank is in heat transfer relationship with the flow means. The flow means preferably includes a valve assembly and the heat transfer element may comprise a spring-like member associated with an end region of the valve assembly extending into the interior of the gas tank. Heat deflector means are suitably located between the burner unit and the fuel reservoir.

IE 0 2 0 7 9 5 In a third alternative aspect, a stove for maintaining prepared food in a warm state according to the invention comprises: (a) a fuel reservoir, (b) a burner unit, (c) flow means communicating between the fuel reservoir and the burner unit; and (d) control means for regulating flow of fuel from the fuel reservoir to the burner unit, wherein heat deflector means are located between the burner unit and the fuel reservoir.

The heat deflector means may comprise a substantially annular member substantially surrounding the flow means, while the fuel reservoir may be a refillable gas tank of less than 250 ml capacity.

In a fourth alternative aspect of the invention, a stove for maintaining prepared food in a warm state comprises: (a) a fuel reservoir, (b) a burner unit, (c) flow means communicating between the fuel reservoir and the burner unit; and (d) control means for regulating flow of fuel from the fuel reservoir to the burner unit, wherein the fuel reservoir is a refillable gas tank of less than 250 ml capacity.

In a particular embodiment, the fuel reservoir has a capacity of between 100 ml and 250 ml. The diameter of the tank is suitably substantially equal to the height of the stove.

A fifth alternative aspect of the invention provides a stove for maintaining prepared food in a warm state, comprising: ¢02079 (a) a fuel reservoir, (b) a burner unit, (c) flow means communicating between the fuel reservoir and the burner unit; and (d) control means for regulating flow of fuel from the fuel reservoir to the burner unit, wherein the diameter of the tank is substantially equal to the height of the stove.

The largest dimension of the tank is preferably less than 120 mm.

In any aspect of the invention, the fuel reservoir preferably comprises a plastics material. Suitably, the fuel reservoir comprises a two-part structure consisting of a substantially cup-shaped body portion and a closure portion for co-operative sealing association with the body portion. Interconnection of the closure portion and body portion of the fuel reservoir may be effected by screwing together, or alternatively by a bayonet-type coupling action. The closure portion may define a base region of the fuel reservoir, or alternatively a top region of the fuel reservoir.

Preferably, at least the flow means incorporates heat exchange features, which may be external cooling fins. Further, the flow means suitably comprises a rotary valve assembly, while the control means may includes a rotary switch for displacement between end positions corresponding to full-flow and shut-off conditions, the control means also optionally enabling adjustment of the rate of release of fuel from the reservoir. Filter means may also be disposed in the flow path for fuel from the reservoir to the burner unit.

There is thus provided by the invention, a catalytic stove which is especially cost-effective, both in respect of manufacture, by virtue of its simple construction and use of low-cost materials, and also in respect of use, because of its employment of a gaseous fuel and the controllability of heat delivery resulting from this. The unit of the IE02 07 9 5 invention incorporates a control feature by which the heat generation can be accurately regulated to match the requirements at any particular time.

The stove of the invention overcomes many of the drawbacks of conventional stoves by including one or more of the following features: a re-usable reservoir for the gas fuel - the reservoir can easily be refilled and reused; a nozzle arrangement that is less prone to blockage by heavy hydrocarbons; a heat transmitter for transmitting heat to the gas to compensate for lowering temperature due to expansion of the gas, thus at least partially rectifying any drop in the vapour pressure of the gas that might otherwise occur; an easily controlled temperature output; a simply constructed yet versatile stove which may be constructed of inexpensive yet durable materials.

Thus the invention provides in a first aspect a split nozzle system that controls the amount of heat conducted back into the body of the burner. This facilitates a compact construction of the burner. The controlled conduction feedback system draws heat back into the gas tank. As gas boils off from the tank, the tank is however cooled, so that an equilibrium is established by which the gas reservoir is maintained at a temperature of approximately 20°C, whereby the vapour pressure of the gas may be maintained. The split nozzle system avoids excessive return conduction of heat, which may prevail if a one piece nozzle system is used, unless the axial extent of the nozzle is increased.

In a further aspect, the deflector substantially precludes or prevents radiant heat from reaching the top of the tank, thereby further ensuring that overheating of the tank is avoided. Deformation of the deflector when heated may also enable the air cap between the components of the split nozzle system to be increased, as the nozzle warms up, by increasing the axial spacing between the components of the split nozzle. ^020735 The invention further provides a filling valve of a construction such that it cannot not be expelled from the tank. This feature is combined with sealing of the tank by a flange or lid member with a peripheral sealing component around its perimeter being supported by a central nut locking the top or lid portion of the tank to the base of the tank by means of a central structural or reinforcing pillar. This pillar also accommodates the filling valve. This central reinforcement assists in spreading forces within the tank and preventing deflection of the plastics components of the tank while under pressure.

BRIEF DESCRIPTION OF THE DRAWINGS Various embodiments of the invention will now be described having regard to the accompanying drawings in which: Figure 1 shows a cross-sectional view of a stove unit according to a first preferred embodiment of the invention, Figure la is perspective view of the stove unit of figure 1 with the top cover removed, Figure 2 is a cross-sectional view of the burner head and switch arrangement of the stove of Figure 1, Figure 2a is a perspective view of the burner head and switch arrangement of the stove of Figure 1, Figure 3 is a cross-sectional view of a gas release valve for use with a stove of the present invention, Figure 4 shows a perspective view of the gas release valve of Figure 3, Figure 5 is a cross-sectional view of a combined fill valve and fuel tank central pillar assembly for use with a stove of the present invention, Figure 6 shows a pictorial representation of a stove unit according to a second embodiment of the invention, Figure 7 is a cross-sectional view of the stove of Figure 6, Figure 8 is an exploded view of the stove of Figure 6, Figure 9 shows a pictorial representation of a stove unit according to an alternative embodiment of the invention, Figure 10 is a cross-sectional view of the stove unit of Figure 9, Figure 11 shows a cross-sectional view of a further embodiment of a stove according to the invention, Figure 12 shows a perspective view of the stove of Figure 11, Figure 13 shows a perspective view of a nozzle for use with a stove of the present invention and in particular with the stove of Figure 11, Figure 14 shows a cross-sectional view of the nozzle of Figure 13, Figure 15 shows a perspective view of a nozzle connector for use with a stove of the present invention and in particular the nozzle of Figure 13, Figure 16 shows a cross-sectional view of the nozzle connector of Figure 15, Figure 17 shows a perspective view of a fill valve assembly for use with a stove of the present invention and in particular with the stoves of figures 6,9 and 11, Figure 18 shows a cross-sectional view of the fill valve assembly of Figure 17, Figure 19 shows in cross-section an alternative embodiment of a stove in accordance with the invention, Figure 20 is a perspective view of the stove of Figure 19, Figure 21 is a cross-sectional view of a further and particularly favoured embodiment of a stove unit according to the invention, and Figure 22 is a cross-sectional view of a combined nozzle, fuel tank central pillar, and fill valve assembly for use with the stove of Figure 21.

DETAILED DESCRIPTION OF THE DRAWINGS As shown in Figures 1 to 20, a stove 1 preferably of the catalytic stove type, according to certain embodiments of the invention, has a catalyst head or burner unit 4 in which heat is developed by combustion of a gaseous fuel, a fuel storage tank 1, and a gas release valve assembly 8 provided with a control feature or switch 3 for turning the stove 1 on and off, and, in certain end-uses of the stove, regulating gas flow during use. Furthermore, the assembly defines a substantially rigid structure which imparts a selfsupporting nature to the stove with the base 30 of the reservoir acting as a stand for the entire unit 1. ΙΕθ2ο?95 In the present embodiments, the burner head or unit 4 operates substantially in accordance with catalytic principles, but nonetheless incorporates a number of innovative technical features directed to the specific objective of achieving a relatively low cost of production. The burner head 4 comprises a burner expansion region 17 and a nozzle portion, which may be a Venturi nozzle. The nozzle portion may be selfcleaning in a manner which will be described in more detail below. The burner head 4 operates in catalytic manner by employing catalytic material 16a and 16b, or 116a, 116b and 116c respectively. The catalytic material 16a and 16b, or 116a, 116b and 116c ensures that the flame, once ignited, will not extinguish, even under windy conditions, as the catalytic material will cause the gas to re-ignite immediately the flame is extinguished by a gust of wind or such like.

The burner unit 4 can only be turned off following ignition, by termination of gas flow to catalytic elements 16a and 16b, or 116a, 116b and 116c. Such termination of gas flow leads to the flame being extinguished.

In a preferred embodiment of the invention, as shown in Figures 1 to 5, the burner head 4 has a stepped construction, each step holding an individual catalyst disc 16a, 16b of equal diameter. The burner 4 of the invention preferably has a minimum of two steps associated with its expansion region 17, but as many as five steps may be provided. Multiple steps of increasing step size in the direction of flow of the gas through the head portion 17 may be provided to facilitate expansion of the gas flow. One or more lateral heat dissipating fins 20 may be provided on the exterior of the burner head 4. The heat dissipating fins 20 may contribute in an innovative manner to the successful performance of the stove 1 of the invention.

The temperature of the catalytic elements 16a, 16b is controllable within a temperature range of between 100°C and 1300°C. The catalyst may emit primarily infrared radiation, for example, in the temperature range of 100°C to 700°C. The stove 1 can thus be used as a source of infra-red radiation, for example for use in therapies such as therapeutic healing. ^020/95 In the embodiment shown in Figures 1 and 2, a deflector in the form of a flat annular deflector disc 6 is attached to the base of the burner head 4 to extend perpendicularly to the flow axis of the head 4. The disc 6 acts to prevent excessive heat from the burner head 4 reaching the tank or reservoir 2. Thus radiant heat emanating from the burner head 4, or from any food-containing vessel supported on the head 4, is prevented from heating the top 31 of the tank 2. The top of the tank 2 accommodates or houses, in the present embodiment, a switch or control feature 3 substantially coextensive in area with the tank top surface 31. The deflector 6 ensures that the top 31 of the tank 2 and the overlying switch arrangement 3 are not subjected to overheating. The efficiency of the catalytic stove 1 is also improved by radiant heat from a chafing dish or other food vessel supported on or located above the burner head 4 being directed back to the dish or vessel. Disc 6 thus has dual functionality, acting not only as a heat shield to protect the gas container 2, but also as a deflector, for returning radiant heat towards the burner head 4 and food container. The deflector disc 6 is usually between 60 mm and 100 mm in outer diameter.

As shown in Figures 1 to 2b, the deflector 3 and burner head 4 arrangement are supported at a substantially defined distance above the top surface of the switch 3 on legs or posts 10. This arrangement results in a vertical air gap being defined between the burner head portion 4 and an upper portion 8 of a gas discharge or release valve assembly. The upper portion 8 extends upwards through the tank top surface 31. Gas passing from the portion 8 to the burner head 4 traverses the air gap, while heat conduction from the burner head 4 back into the body of the tank 2 is reduced. There is no heat conduction across the air gap. The only transfer of heat across this air gap is by radiation. The spacers, posts or legs 10 support the deflector disc 6 at a predetermined spacing above the switch top surface. Each spacer 10 is secured to the deflector disc 6 by a domed bolt 10a. The lower end of each spacer 10 is bolted to the switch or control feature 3 overlying the upper surface 31 of the tank 2.

A suitable material for the deflector disc 6 is a heat reflecting material, preferably a metal. In a favoured embodiment, the deflector disc 6 is formed from a metal which deforms or buckles under the actions of heat, such as brass or copper. The IE Ο 2 07 9 5 disc 6 may alternatively be bimetallic. When the disc 6 heats up, controlled buckling or deformation occurs, so that as the deflector deforms, the centre of the deflector disc 6 is displaced vertically, i.e. in the direction of the axis of gas flow. Upward displacement of the disc, away from the tank portion 2 of the stove 1, raises the burner head 4 so that the air gap between the burner head 4 and the gas discharge portion 8 is increased in a controlled manner. The air gap may increase, as the unit heats up, from 1 mm to 2 mm or 3 mm.

The objective is thereby achieved of getting as much heat as possible into the gas fuel in the tank 2 at the start of the operation, in order to warm it up as quickly as possible to encourage gasification. As soon as the gas in the tank 2 is warmed up sufficiently, the widening of the gap controls and reduces the extent of the heat transfer from the burner head 4 back into the tank 2.

A gas release or discharge valve assembly for use with the present invention is shown in Figures 3 and 4. A cross-sectional view is shown in Figure 3. The majority of the lower portion of the assembly is mounted in the upper part of the fuel storage tank 2 and is hidden from external view, as will be apparent from Figure 1.

The main parts of the assembly are an upper flow portion 8 defined by a sleeve and a nozzle connector portion 51 which has an internal cavity 52. An orifice holder 53 is accommodated in the cavity 52. The orifice holder 53 has two main functions, namely first of all to provide a domed end 55 in which there is defined an orifice (not shown) through which the gas passes, and secondly to hold an orifice filter 54 which filters the gas exiting through the orifice. This orifice acts as the jet for combustion of the gas. The dome shape 55 provides for clean burning of the gas fuel, as deposits are less likely to collect about the orifice. An O-ring 56 is provided so that the sleeve portion 50 is sealingly engageable in the nozzle connector 51. An external serrated portion 77 enables co-operation of the gas control valve assembly with corresponding serrations 27 on the switch portion 3 for rotation of the gas release valve between open and closed end positions and optionally also to vary and control or regulate the rate of gas discharge from the reservoir. ΙΕΟ 2 07 9 5 The entire gas valve assembly structure is adapted to be received into a corresponding mounting arrangement 61 provided in a central pillar 60 of the tank 2, as shown in Figure 5. The central pillar 60 is held in position by a nut which locks the top and bottom of the tank 2 together. This detachable feature of the assembly allows for removal of the nozzle and gas valve assembly for servicing and/or replacement of the filter 54.

As best seen in Figure 1, a switch portion 3 overlies the upper surface 34 of the fuel tank 2, which is not normally visible to the user. The switch portion 3 engages around the external periphery of the gas valve assembly such as by way of serrations or splines 27, so that rotation of the switch 3 effects corresponding rotation of the nozzle and gas valve. A retaining nut 5 secures the switch portion 3 onto the gas release valve.

The gas discharge valve is rotatable relative to the mounting znaagemeat 61 prov ided m the central pillar 60 of the tank 2, in order to open and dose the gas flow path. There is sealing between the gas valve assembly and the mounting arrangement 61 by an O-ring 64 disposed between the respective internal surfaces of the gas valve assembly and the mounting arrangement 61. Internal 0-rings 58,59 are provided in grooves along the periphery of the gas valve assembly to establish sealing between the outer surface of the gas valve assembly and the internal surface of the mounting arrangement 61.

To switch the flow on and off and to control or regulate the flow rate of the fuel, the entire burner head 4, deflector 6, switch 3 and nozzle arrangement may be rotated through 270°between respective end positions. This rotary movement is accomplished by manual rotation of the external switch portion 3.

Figures 2 and 2a show the combined switch 3, burner head 4, and deflector 6 assembly in greater detail. Suitably, the switch 3 is disc shaped with a downwardly extending peripheral skirt 22, the disc portion of the switch 3 having a diameter approximately equal to that of the tank 2. The downwardly extending peripheral skirt 22 ¢^2 07 9 5 15 is substantially coaxial with a cylindrical outer wall of the gas tank 2. The peripheral skirt region 22 is provided with raised radially projecting vertical grips or ribs 23 for ease of gripping for manual turning.

The switch arrangement 3 described enables close and accurate regulation of the supply of fuel from the tank 2 of the unit to the burner head 4 and thereby facilitates adjustment of the heat release from the stove 1 to the items to be heated. In this way, not only is economy in usage of fuel achieved, but in chaffing use, the degree of heating applied to the food to be kept warm can be matched exactly to requirements, so that the correct temperature is maintained, but there is minimal continuing cooking of the prepared dishes. Thus excellent chaffing performance is provided by the unit 1 of the invention.

The srove unit 1 contains a gas supply for providing the requisite heat output by combiaixxi of the gas in the vidnhy of the catalyst discs 16a and 16b. The gas is held in liquid form in the tank 2.

The main body of the tank 2 according to the first embodiment of the invention, as shown in Figures 1 to 5, is of a two part construction 2a, 2b. A plastic cupshaped portion or tank body 2a with a substantially flat base forms the base and sides of the tank, closed off at its upper end by an upper closure portion or tank lid 2b.

Top portion 2b is defined by a generally disc-shaped part 11 with an integral downwardly-depending skirt 12, which extends into the cup-shaped base 2a in the assembled condition of the gas tank 2. In the embodiment of Figure 1, the tank top 2b is connected to the tank body 2a by a bayonet fitting. A bayonet assembly 36 may serve to connect the lid 2b to the tank body 2a and is most suitably one-way, i.e. once the tank top 2b and body or base 2a have been assembled by a relative twisting movement, they cannot readily be separated again. Reverse movement of the bayonet arrangement 36 is inhibited to preclude reopening the tank 2 in this manner. Sealing between the two tank portions 2a, 2b is completed by a sealing ring 13 held in a recess on the periphery of the downwardly-directed skirt 12 of the upper closure portion 2b near its lower edge. The ¢0 2 07 9 centre of the top surface of the upper closure portion 2b is provided with an aperture through which the tank’s central pillar 60 extends in an upwardly direction.

The particular shape of the tank 2 represented in Figure 1 is not definitive. In alternative embodiments, a dome shaped upper surface may be provided.

As seen in Figure 1, an overall tank cover 14 is further provided to enclose the burner region during transport or storage. The top cover 14 is arranged to snap down onto the tank portion perimeter over the control switch 3.

In any embodiment of the invention, in order to provide an economical and visually attractive construction, the tank 2 for the liquid gas is made from a plastics material. The capacity of the unit 1 as represented in the drawings is substantially 160 ml. A preferred diameter for the tank 2 is 95 mm and the overall height of the entire unit 1, from the base of the tank 2 to the top of the burner head 4, is suitably 95 · 101 mm.

A particular novel feature of the container or tank 2 of the stove unit 1 of the invention is that it is refillable through a fill valve 7 provided in the base of the tank 2. A refilling feature is believed not to have been hitherto provided in a container of the dimensions or proportions applied in the present instance.

Figure 5 shows a fill valve assembly 70 according to the preferred embodiment of the present invention, in more detail. The valve comprises a housing 71 and valve spool 73 displaceable against a compression spring 76. An internal O-ring 75 provides internal sealing and external O-rings 74 provide sealing between the fill valve assembly and valve-receiving portion of the tank 2. An external serrated portion 71 enables retention of the valve portion within the tank base against rotation.

The filler valve in the present embodiment is modified to preclude possible discharge of liquid gas during filling operation by way of the air venting feature of the filling valve structure. The avoidance of such unwanted discharge of liquid gas is ΙΙζΰ 2 achieved, inter alia, by the provision of an additional sealing member within the filling valve structure. When the filling valve is depressed, gas flows into the valve through an axial channel within the valve member and flows out to the sides of the valve member at suitable windows or transversely directed openings. In this way, gas enters into the interior of the tank. Air to be vented exits through a further transverse passage, above the liquid level of the gas in the inverted disposition of the tank, this air exit passage being located near the outer or tank base end of the valve. The vented air then reaches the external ambient environment through a small air gap defined between the sliding member of the valve and an outer sleeve of the valve structure. This air gap is of controlled dimensions to regulate the rate of exit of the air. The seal provided in the present embodiment of the filling valve precludes any liquid gas from being entrained in this air flow.

The filler valve is also mounted in a central structural pin, preferably of brass, when enables positive retention of the filler valve within the structural unit, so that it cannot blow out of the tank and stove assembly. The central structure also acts a central supporting pillar, extending throughout the axial extent of the tank and linking the lid to the base, so that lid and base are securely fastened together in the assembled condition of the stove. Thus the filler valve is assembled as part of the overall assembly operation and is not inserted as an independent unit following completion of the remaining assembly operations.

The pillar structure carries central forces within the assembled tank to improve its structural stability under pressurisation and provides reinforcement of the substantially cylindrical tank along its central axis of symmetry, coupling the tank lid or flange to the base of the tank. The pillar is held in place but a nut which engages against the lid or flange. Suitable sealing features ensure gas-tightness of the assembled stove structure and in particular of the central pillar with respect to the tank or reservoir. In the present construction, the valve is part of the central pillar assembly and is retained positively against possible expulsion from the tank under extreme conditions. The filler valve is thus not dependent on any kind of non-retum claw type engagement, following initial insertion, and neither is it dependent on any kind of latching holding arrangement such as a circlip or other spring clip feature.

The central pillar 60 includes an external O-ring seal 63 for sealing engagement of the central pillar within the tank lid 2b when the central pillar is assembled with the tank lid 2b. An adjuster screw may also be provided in the gas flow path.

Refilling can be effected using standard butane or propane containers. Each such standard container of capacity 300 ml provides approximately two refills for the tank of the unit of the invention.

The liquefied gas used is preferably butane or a propane/butane mix ratio of 30:70 to 1:100. A particular statutory requirement for the pressure resistance of propane/butane containers is 20 bar. The designs of tank provided in conjunction with the present invention are expected to be pressure resistant up to 50 to 60 bar.

In order to achieve this strength, the material of the tank is suitably a particularly tough plastics material, for example a glass-filled nylon with a glass transition temperature greater than 60 degrees Celsius. Alternatively, nylon may be used on its own, with no glass-filling. Typical wall thickness is 4 mm to 5 mm, and the range of wall thickness is normally at least 3 mm to 6 mm. In general, it is anticipated that the minimum wall thickness will not be less than 3 mm, while the maximum wall thickness is unlikely to require to be greater than 6 mm. Above 6 mm, the balance between economy and strength becomes less favourable.

The structure of the tank as described herein is resistant to any pressure exerted by the liquid gas within the tank. At ambient pressure, the contents of the tank in liquid form in fact exert a pressure of no greater then 4-6 bar, but because of the relatively large quantity of fuel held within the tank, the consequences of any inadvertent leakage or fracture of the tank are nonetheless potentially hazardous, possibly explosive. Hence the necessity for the tank to possess appropriate strength and to be substantially leak5 proof. The tank may be finished in a choice of colours, or alternatively, the finished unit may be coated in a shiny metallic material or otherwise metallised.

Figures 6 to 20 describe alternative embodiments of a stove according to the invention.

In these embodiments, the burner unit 4 is directly connected to a fuel storage tank 2 by way of a valve assembly 8 provided with a control feature or switch 3 for turning the stove 1 on and off, and, in certain end-uses of the stove, regulating gas flow during use. The burner unit 4 is mounted directly on the reservoir and in particular is securely attached thereto to define a substantially rigid assembly. The mounting of the burner 4 directly on the reservoir allows for a very compact arrangement of the stove of the invention. Furthermore the substantially rigid assembly imparts a self-supporting nature to the stove with the base 30 of the reservoir acting as a stand for the entire unit.

In the present embodiments, the burner head or unit 4 operates substantially in accordance with catalytic principles, but nonetheless incorporates a number of innovative technical features directed to the specific objective of achieving a relatively low cost of production. The burner 4 comprises a portion 17. The burner 4 operates in catalytic manner by employing catalytic material 16a and 16b, or 116a, 116b and 116c respectively. The catalytic material 16a and 16b, or 116a, 116b and 116c ensures that the flame, once ignited, will not extinguish, even under windy conditions, as the catalytic material will cause the gas to re-ignite immediately the flame is extinguished by a gust of wind or such like.

The burner unit 4 can only be turned off (i.e. to extinguish the flame), following ignition, by termination of gas flow to catalytic elements 16a and 16b, or 116a, 116b and 116c.

In one embodiment of the invention, the burner 4 has a stepped construction, each step holding an individual catalyst disc 16a, 16b of equal diameter. The burner 4 of the invention preferably has a minimum of two steps in its portion 17 but as many as five steps may be provided. The provision of multiple steps is to provide for expansion of the gas flow. The increasing step size is in the direction of flow of the gas through the portion 17. It is a further feature of the invention that the burner 4 can be removed from the valve assembly 8 in one piece by virtue of, for example, a screw connection to the valve assembly 8.

The temperature of the catalytic elements is controllable within a temperature range of between 100°C and 1300°C. The catalyst may emit primarily infra-red radiation for example in the temperature range of 100°C to 700°C. The stove can thus be used as a source of infra-red radiation, for example for use in therapies such as therapeutic healing.

A cylindrical jet 15, is positioned within the burner 4, beneath the catalytic discs 16a, 16b, or 116a, 116b, 116c. The jet or conduit provides a pathway for flow of gas from the tank or reservoir to the burner 4.

In the embodiment of Figures 6-8 , a deflector in the form of a flat annular deflector disc 6 is positioned horizontally externally of head 4 and below the burner 4. The disc acts to deflect heat from the tank or reservoir 2, for example to prevent radiant heat emanating from the burner head 4, or any food-containing vessel supported on the head 4, from heating the top 31 of the tank 2. The top of the tank 2 houses, in the present embodiment, a switch or control feature 3 substantially coextensive in area with the tank top surface 31. The deflector 6 ensures that the top 31 of the tank 2 and the switch arrangement 3 overlying it does not overheat. The efficiency of the catalytic stove 1 is also improved, by re-radiating the radiant heat from a chafing dish or other food vessel back to the dish or vessel. The deflector disc 6 is usually between 60 mm and 100 mm in diameter. A suitable material for the deflector disc 6 is a heat reflecting material, such as (a reflective) metal. Disc 6 thus has dual functionality, acting as a heat shield to protect the gas container, and also as a deflector, for returning radiant heat towards the burner and food container.

In the embodiment of Figures 6 to 8, the burner 4 and deflector 6 arrangement are fixedly attached to each other and are together releasable attached to a substantially standard gas valve 8. In the embodiment of Figures 9-10, no deflector 6 is provided, but otherwise the arrangement is generally similar, having the burner 104 and the valve 108. Within the valve 8, a fixed flow nozzle is provided, resulting in an economical and cheap construction. The nozzle is a Venturi type. The nozzle also contains a replaceable filter 18. The nozzle of Venturi construction is designed so as to be self-cleaning. A major problem with many conventional nozzle types is that they have a tendency to block with dust. This may happen due to heavier hydrocarbon impurities in the gas collecting about the orifice of the nozzle due to their generally lower expulsion velocity from the nozzle. These hydrocarbon deposits can attract dust and other particles and may eventually block the nozzle orifice. One particular method of avoiding such blockage is to adopt the nozzle arrangement shown in the present invention where the expanding fuel flow path (stepped in the embodiments shown) allows the heavier hydrocarbons to fall away from the orifice of the nozzle.

The entire nozzle, valve 8 and burner 4 assembly can be readily taken apart for servicing and/or replacement of the filter 18 and any other component as may be required. The valve 8 is provided with lateral heat dissipating fins 19 about its upper cylindrical portion 8a which extends upwardly toward the top of the burner 4. A second set of larger more spaced apart fins 20 are provided closer to the top end 32 of the burner. The heat dissipating fins, in particular the set 20 on the burner head, contribute in an innovative manner to the successful performance of the stove of the invention. The lower portion 8b of the valve assembly 8 is mounted in the upper part of the fuel storage tank 2 and is hidden from external view, as will be apparent from the Figures.

It will be appreciated that the top end 32 of the head of the burner unit acts as a stand, seat or support on which an item to be heated may be placed - for example a kettle or heating dish or tray.

The flow of fuel from the tank 2 to the burner 4, is controlled by relative rotation of the burner 4, and the tank 2. For example, in the embodiment shown in Figures 6 to 10, the entire upper end of the burner structure, namely the upper valve portion 8a and burner head 4, may be rotated through 270°, to switch the flow on and off and to control or regulate the flow rate of the fuel. The switch is thus displaceable between respective end positions. This rotary movement is accomplished by an external switch portion 3, of the tank 2, mounted to surround the valve assembly 8 a short distance below the heat dissipating fins 19.

In particular, the switch portion 3 engages around the external periphery of the valve assembly 8, such as by way of splines, so that rotation of the switch effects corresponding rotation of the valve. Rotation of the valve controls the flow rate of gas through the valve and thus from the tank 2 to the burner. Suitably, the switch 3 is disc shaped with a downwardly extending peripheral skirt 22, the disc portion of the switch having a diameter approximately equal to that of the tank 2. The downwardly extending peripheral skirt 22 is substantially coaxial with a cylindrical outer wall 33 of the gas tank 2. The switch portion 3 overlies the upper surface 34 of the fuel tank 2, which is not normally visible to the user. The peripheral skirt region 22 is provided with raised radially projecting vertical grips or ribs 23 for ease of gripping for manual turning. End stops 24 to limit the rotational displacement of the control disc 3 are provided on the underside of the switch portion 3 for co-operation with upstanding projections or lugs 25 extending from the upper portion or top surface 34 of the tank 2. These technical features of the switch 3 are hidden from external view in the assembled structure as seen in Figure 6. A retaining nut 5 is provided to secure the switch portion 3 on the valve 8.

The entire valve 8 and burner 4 assembly structure is screw threadingly connected to a mounting arrangement in an upper portion of a fuel storage portion of the apparatus, i.e. the tank 2. This detachable feature of the assembly allows for compact storage of the stove 1, in particular during hiking, camping etc. The tank 2 contains a gas supply for providing the requisite heat output by combustion of the gas in the vicinity of the catalyst discs 16a and 16b, or 116a, 116b and 116c. The gas is held in liquid form in the tank 2.

The main body of the tank 2 according to the embodiment of the invention shown in Figures 6-8 is of a two part construction 2a, 2b. A plastic cup-shaped portion 2a with a concave base forms the base and sides of the tank, closed off at its upper end by an upper closure portion 2b which is screwed into the main body or cup-shaped lower portion 2a of the tank 2. Top portion 2b is defined by a dished or concave generally disc-shaped part with an integral downwardly-depending skirt, which extends into the cup-shaped base 2a in the assembled condition of the gas tank. The screwing-in takes place by way of a deep cut thread 26 provided on the downward peripheral skirt of closure portion 2b, which thread is resistant to any pressure exerted by the liquid gas within the tank 2. Sealing between the two portions is completed by a sealing ring 11 held in a recess on the periphery of the downwardly-directed skirt of the upper closure portion 2b near its lower edge. The top surface of the upper closure portion 2b is, as already noted, concave. The centre of the concavity is provided with an aperture to furnish the mounting arrangement into which the valve assembly 8 fits and in which it is secured by a nut 9. The nut 9 further comprises an annular receiving portion or lip at its base, onto which a heat transmitter such as a spring may be attached, as will be described below.

The lower portion 8b of the valve assembly 8 extends through the mounting arrangement into the interior of the tank 2. A hole is provided horizontally through the lower end of the valve, through which a cylindrical wick 13 is fed. Inside the tank 2, this lower portion 8b of the valve is surrounded by a bell-shaped heat spring 12, the top of which is associated with the body of the tank and the valve assembly 8 by means of the receiving portion of the nut 9. The heat spring 12 defines a conductive feedback system ΙΕΟ 2 0 7 9 5 which returns heat from the burner and valve assembly back into the heat tank 2. As the gas boils off, it cools. The conductive feedback system keeps the gas reservoir at temperatures around 20U, thus helping the gas to maintain its vapour pressure.

The design of the individual parts of the stove according to this embodiment of the invention allows for ease of assembly as described below.

The pre-assembled gas valve 8 is lowered into the central aperture of the upper closure portion of the tank and is secured at its base by the nut 9. The heat spring may then be attached to the nut/valve assembly. The wick 13 is fed through its corresponding hole at the base of the valve 8, and the assembled upper closure portion 2b of the tank is subsequently screwed into the lower cup-shaped portion 2a of the tank. The switch portion 3, followed by the valve nut, is lowered over the upper part of the valve which is now extending from the top of the tank 2. The switch comes to rest on the top surface of the tank. Tightening of the nut secures the switch to the valve. Finally, the burner and deflector arrangement is attached to the top of the valve. The assembled stove is now ready for filling before operating.

Figures 9 and 10 show a third embodiment 101 of the stove according to the invention. In this second embodiment, as shown in Figure 10 in particular, the stepped construction of the burner head 104 again narrows or tapers in a downward direction (in the opposing direction to the direction of flow of the gas), with each step holding an individual catalyst disc 116a, 116b, 116c. As shown in Figure 10, the burner head 104 has three steps and is provided with three catalytic discs 116a, 116b, 116c, each of increasingly greater diameter in the upward or ascending direction. The burner unit 104 of the invention preferably has a minimum of two steps, but as many as five steps may be provided. The provision of multiple steps with a widening or tapering outflow region in the upward direction is to provide for expansion of the gas flow. (Expansion occurs in the direction of flow). It is a further feature of the invention that this catalytic head 104 can be removed from the valve 108 in one piece by virtue of, for example, a screw connection to the valve 108. ¢02 0 7 9 5 Moving downward from the burner head 104, the feed tube or valve 108 is provided with lateral heat dissipating fins 119, as also is the lower region of the burner head 104 itself. The burner head fins are designated by reference 120. The use of the heat dissipating fins 119 in both sections contributes in an innovative manner to the successful performance of the unit 101 according to the invention.

Within the valve 108, a fixed flow nozzle 117 is provided, resulting in an economical and cheap construction. The valve region of the unit also contains a replaceable filter 118. The entire nozzle 117, valve 108 and catalyst head 104 assembly can be readily taken apart for servicing and/or replacement of the filter 118 and any other component as may be required. In particular, the lower end 108b of the valve is screw threadingly connected to a mounting arrangement fitted into the top of the tank 102 and adapted to secure and accommodate the nozzle portion 117 and the filter 118.

In order to control the flow of fuel from the tank 102 to the burner 104, the entire upper end of the burner structure, namely the valve 108 and burner head 104, may be rotated through 180° between end positions, to switch the flow on and off. This rotary movement is accomplished by an external adjustment knob 103 mounted to surround the lower end 108b of the valve 108 and engaging on the external periphery of the valve by way of splines or longitudinal protrusions 121. Referring again to Figure 9, a radially extending lug or tab 128 provides for displacement of the knob between the open and closed positions by manual engagement. End stops (not shown) to limit the rotational displacement are provided within the adjustment knob structure 103 for co-operation with at least one upstanding projection or lug 125 between the switch 103 and body of the tank 102. Suitably the switch 103 is of disc shape with a downwardly extending peripheral skirt 122, within which the other technical features of the knob arrangement are hidden from external view in the assembled structure as seen in Figure 9. The diameter of the switch 103 is approximately half that of the fuel tank 102.

This alternative embodiment does not feature the heat shield or deflector of the construction first described. The control switch arrangement is of lesser diameter than ΙΕ Π 2 0 7 g 5 that of the gas tank and requires therefore a lesser degree of shielding than does the larger switch of the first embodiment.

The main body of the tank 102 consists of an inverted cup-shaped portion 102a, closed off at its lower end by a closure portion 102b which is screwed into the main body or inverted cup part 102a of the tank. The screwing in takes place by way of a deep cut thread 126, which is resistant to any pressure exerted by the liquid gas within the tank 102. Sealing is further guaranteed by an O-ring or similar seal accommodated in a peripheral groove provided in the threaded annular skirt portion of closure 102b, which skirt portion carries the screw thread 126. At ambient pressure, the contents of the tank 102 in liquid form in fact exert a pressure of no greater then 4-6 bar, but because of the relatively large quantity of fuel held within the tank 102, the consequences of any inadvertent leakage or fracture of the tank 102 are nonetheless potentially hazardous, possibly explosive. Hence the necessity for the tank 102 to possess appropriate strength and to be substantially leak-proof.

The particular shapes of the tank 2 represented in Figures 6 to 10 is not definitive. In alternative embodiments, a dome shaped upper surface may be provided.

In any embodiment of the invention, in order to provide an economical and visually attractive construction, the tank for the liquid gas is made from a plastics material. The capacity of the unit as represented in the drawings is substantially 160 ml.

A preferred diameter for the tank is 95 mm and the overall height of the entire unit, from the base of the tank to the top of the burner, is also suitably 95 mm.

A particular novel feature of the container or tank of the unit of the invention is that it is refillable through a fill valve 7 at the base of the tank 2 which is believed not to have been hitherto provided in a container of the relatively large dimensions or proportions applied in the present instance. This refillable capability can be effected using standard butane or propane containers, each such standard container of capacity 300 ml providing approximately two refills for the tank of the unit of the invention. ο; The liquefied gas used is preferably butane or a propane/butane mix ratio of 30:70 to 1:100. A particular statutory requirement for the pressure resistance of propane/butane containers is 20 bar. The designs of tank provided in conjunction with the present invention are expected to be pressure resistant up to 50 to 60 bar.

In order to achieve this strength, the material of the tank is suitably a particularly tough plastics material, for example a glass-filled nylon. Alternatively, nylon may be used on its own, with no glass-filling. Typical wall thickness is 4 mm to 5 mm, and the range of wall thickness is normally at least 3 mm to 6 mm. In general, it is anticipated that the minimum wall thickness will not be less than 3 mm, while the maximum wall thickness is unlikely to require to be greater than 6 mm. Above 6 mm, the balance between economy and strength becomes less favourable.

The stracxure of rhe rank as described herein is resistant to any pressure exerted by the liquid gas within the tank. At ambient pressure, the contents of the tank in liquid form in fact exert a pressure of no greater then 4-6 bar, but because of the relatively large quantity of fuel held within the tank, the consequences of any inadvertent leakage or fracture of the tank are nonetheless potentially hazardous, possibly explosive. Hence the necessity for the tank to possess appropriate strength and to be substantially leakproof. The tank may be finished in a choice of colours, or alternatively, the finished unit may be coated in a shiny metallic material or otherwise metallised.

Figures 11 and 12 show a fourth embodiment of the invention, this being of generally similar construction to that of Figures 6 to 8. The same reference numerals are applied in the drawings as for Figures 6-8.

A nozzle assembly for use with the present invention is shown in Figures 13 and 14. The nozzle assembly is generally designated 40 and is shown in perspective view in Figure 13. A cross-sectional view is shown in Figure 14. The nozzle assembly is shown without the catalytic head. The main parts of the assembly are a body portion 41, having a cavity 42 defined therein. In the cavity 42 is housed a holder 43. The holder 43 has two main functions, namely first of all to hold a sintered filter 44 which filters ΙΕΠ2 07 g5 the gas coming through the nozzle assembly, and secondly to hold a domed piece 45. Dome 45 in turn has defined therein an orifice through which the gas passes. This orifice acts as the jet through which the gas is burned. An O-ring 46 is provided so that the nozzle is sealing engageable in the structure of the burner. The dome shape provides for clean burning of the gas fuel as deposits are less likely to collect about the orifice.

The remainder of the assembly includes fins 47 on the body and a head 48 for accommodation of the catalytic element(s).

Figures 15 and 16 show a connector piece 60 for connecting the nozzle assembly of Figures 13 and 14 to the tank 2. When in place, the connector piece 60 is seated between the upper portion 2b of the tank 2 and the switch portion 3. The connector piece 60 has two main body parts - a first upper part 61 for engagement with the switch portico 3 and a second lower part 62 which engages with the upper part 2b of the tank 2. The arrangement of the connector piece 60 within the burner structure is best seen for example from Figure 7. The parts 61 and 62 are rotatable relative to each other to open and close gas flow. There is sealing between parts 61 and 62 by an O-ring 64 disposed between internal surfaces 65 of the connector. Internal 0-rings 65,67 are provided in grooves along the periphery of the part 61 to provide sealing between the outer surface of part 61 and the internal surface of part 62.

The connector piece 60 includes an external O-ring seal 63 for sealing placement of the connector within the overall assembly. The serrated or keyed rim engages within the top part 2a of the tank. An adjuster 68 is also provided in the gas flow path.

Figures 17 and 18 show a fill valve assembly 70 in more detail. The fill valve is generally indicated by the reference numeral 7 in earlier figures and is depicted in most detail in Figure 11. The valve comprises a housing 71 and valve spool 73 displaceable against a compression spring 76. An internal O-ring 75 provides internal sealing and external O-rings 74 provide sealing between the fill valve assembly and valve-receiving portion of the tank 2. An external serrated portion 77 enables retention of the valve portion within the tank base. ¢0 2 0 7 9 5 Referring now to the embodiment of Figures 19 and 20, this is generally similar to that of Figures 11 and 12 in having a substantially pot-shaped lower tank body portion 2b closed at its upper periphery by a tank lid or cover portion 2a. Those features of these drawings which are the same as those of earlier figures are indicated by the same reference numerals. The principal differences reside in the tank top 2a being connected to the tank body 2b by a bayonet fitting 36 rather than the screw thread 26 previously described, and the provision of an overall top cover 37, to enclose the burner region during transport or storage. The top cover 37 is arranged to snap down onto the tank portion perimeter over the control switch 3. The bayonet assembly 36 is most suitably one-way, i.e. once the tank top 2a and body or base 2b have been assembled by a relative twisting movement, they canoe* readily be separated again. Reverse movement of the bayonet arrangesaesr » a&shtted to preclude reopening the tank in this manner.

Figures 21 and 22 show a sixth, and particularly favoured, embodiment of the invention. This embodiment is generally similar to that of Figures 1 to 5 in that the deflector 3 and burner head 4 arrangement are suspended at a substantially defined distance above the top surface of the switch 3 on legs or posts 10. The principal difference resides in the upper flow portion 8 of the gas release valve assembly having an elongated projecting sleeve 50. The elongate sleeve 50 extends up through the centre of the switch portion 3, bridges the vertical space between the switch surface 3 and the deflector disc 6, and is received into the mouth of the head portion 17 at the base of the burner head 4. A circumferential air gap is formed between the external wall of the sleeve 50 and the interior wall of the portion 17 of the burner head.

In this embodiment, heat conduction from the burner head 4 back into the body of the tank 2 is reduced. There is no heat conduction across the air gap. The only transfer of heat across this air gap is by radiation.

Figure 22 is a cross-sectional view of a combined gas release valve assembly, fueltankcentral pillar 60, and fill valve assembly for use with the stove of Figure 21.

The central pillar 60 is effectively in two parts. The lower part 60a houses the fill valve assembly which is generally similar in construction to the fill valve arrangements already described, in particular in connection with Figures 1 to 5. The upper part 60b of the central pillar 60 houses a mounting arrangement 61 into which the gas release valve assembly is received. O-rings 58,59 are provided for sealing engagement of the gas release valve assembly within the mounting arrangement.

Those features of these drawings which are the same as those of in previous embodiments are indicated by the same reference numerals.

Claims

1. A stove for maintaining prepared food in a warm state, comprising: (a) a fuel reservoir, (b) a burner unit, (c) flow means communicating between the fuel reservoir and the burner unit; and (d) control means for regulating flow of fuel from the fuel reservoir to the burner unit, wherein the fuel reservoir is a gas tank, and means are provided for controlling heat transfer from the region of the burner unit to the interior of the gas tank.

2. A stove according to Claim 1. wherein said heat transfer «saroihag zscass composes a heat deflector located between the burner unit and the fuel ieservce

3. A stove according to Claim 2, wherein said heat deflector comprises heat activated deformation means.

4. A stove according to any preceding claim, wherein said burner unit and said flow means are separated by an air gap.

5. A stove according to Claim 4, wherein the air gap is linear.

6. A stove according to Claim 4, wherein the air gap is circumferential.

7. A stove for maintaining prepared food in a warm state, comprising: (a) a fuel reservoir, (b) a burner unit, (c) flow means communicating between the fuel reservoir and the burner unit; and (d) control means for regulating flow of fuel from the fuel reservoir to the burner unit, wherein the fuel reservoir comprises a reinforcing pillar.

8. A stove according to Claim 7, wherein said reinforcing pillar extends between a region of the reservoir in which said control means is incorporated and a base region of the reservoir.

9. 10 9. A stove according to Claim 8, wherein a gas fill valve is accommodated in said pillar in the vicinity of the base region of the reservoir. 10. A stove according to Gaim 9. ^ herein said fill valve is positively retained within said pillar. if

10. 11. A stove according to Gains 9 of Gaas 3 C. waertjn a seal is provided to substantially inhibit discharge of liquid gas through a fill valve air vent passage, during a gas filling operation. 20

11. 12. A stove according to any of Claims 8 to 11, wherein the reservoir is substantially cylindrical and the central pillar is centrally located within the reservoir along an axis of symmetry thereof.

12.

13. A stove according to Claim 7, wherein said fuel reservoir is a refillable gas tank 25 of less than 250 ml capacity.

14. A stove according to Claim 13, wherein the diameter of the tank is substantially equal to the height of the stove. 30

15. A stove according to any preceding claim, wherein the fuel reservoir comprises a plastics material. ¢02 07 35

16. A stove according to Claim 15, wherein the fuel reservoir comprises a two-part structure consisting of a substantially cup-shaped body portion and a closure portion for co-operative sealing association with the body portion. 5

17. A stove according to Claim 16, wherein interconnection of the closure portion and body portion of the fuel reservoir is effected by screwing together or by a bayonettype coupling action.

18. A stove according to any preceding claim, wherein at least the flow means 10 incorporates heat exchange features.

19. A stove according to any preceding claim, wherein the flow means comprises a rrxx—, νχΚτ assembly and the control means includes a rotary switch for displacement sac posmoss corresponding to full-flow and shot-off conditions. X. A stove substantially as described herein with reference to and as shown in any one or more of the accompanying drawings.