-1 P/00/011 28/5/91 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Noel Bourke Actual Inventor Noel Bourke Address for service is: WRAYS Ground Floor, 56 Ord Street West Perth WA 6005 Attorney code: WR Invention Title: COOKING DEVICE The following statement is a full description of this invention, including the best method of performing it known to me:- -2 "Cooking Device" Field of the Invention The present invention relates to a cooking device. More particularly, the cooking device of the present invention utilises at least solar energy to achieve a desired 5 cooking temperature. Background Art Solar energy has been harnessed for the purpose of cooking for many years. Solar cooking devices work by absorbing and retaining heat from the sun through the use of dark surfaces. To date, there have been three main types of "solar 10 cookers", these are box cookers, curved concentrator cookers and panel cookers. Box cookers generally comprise a box having a lid with a reflective surface to reflect heat onto the interior base of the box. The interior base is generally a dark surface, often painted black. The interior sides of the box may also be reflective to help concentrate heat to the centre, but often they will also be a dark coloured 15 surface to absorb and retain heat from sunlight. A pot can be placed into the box which heats up to temperatures sufficient to cook food. Box cookers are cheap and easy to construct and use. However, they are generally inefficient as their ability to collect heat is dependent on their size. Simply making them larger means that the area they are required to heat becomes larger. Also, their upper 20 temperatures are relatively limited being about 1500C, although generally most solar cookers may not get much higher than about 100*C - 1200C. Thus, cooking times can also be quite long. There are a number of variations of curved concentrator cookers, or 'parabolic' cookers. These cookers comprise a curved reflective surface, which directs heat 25 to a centre point. Parabolic cookers are capable more rapid cooking times and higher temperatures when compared with box cookers. However, they require -3 frequent adjustment and they raise greater safety concerns, particularly with regard to eye protection. Parabolic cookers are generally also quite large and storage can be an issue. Panel cookers are arguably the most popular of the solar cookers. These cookers 5 incorporate features of both parabolic and box cookers. They generally comprise a series of reflective panels forming a base and curved walls which reflect heat back down onto black or dark coloured cooking surfaces (such as a pan). These cookers can be folded for easy storage and are easy to construct. Funnel cookers are generally formed from a sheet of reflective material which is 10 curled into a funnel to direct light down to the apex, where the item to be cooked is placed. Again, these are easy to construct and store, but they are not generally as efficient. With many of these cookers, in order to obtain higher temperatures one simply makes the reflective surface bigger. However, the shape of these cookers often 15 means that larger reflective surfaces make the cooker much more difficult to work with (more cumbersome), less adjustable or significantly less portable. With parabolic cookers in particular they are much more difficult to store because of their large shape and size. The cooking device of the present invention has one object thereof to substantially 20 overcome one or more of the abovementioned problems associated with the prior art, or to at least provide a useful alternative thereto. The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part 25 of the common general knowledge as at the priority date of the application. Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to '-4 imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. It is understood that the term "remote" in respect of the remote heat collector, is intended to mean that the remote heat collector does not itself form the cooking 5 surface. The term "insulating material" is intended to depict materials which retain heat and/or reduce the rate of heat transfer including, for example, fibreglass batts or bricks. Disclosure of the Invention 10 In accordance with the present invention there is provided a solar cooking device comprising: a cooking surface; a remote solar heat collector; and a heat transfer passage, 15 wherein the heat transfer passage is located adjacent at least a portion of the remote solar heat collector and extends to a point adjacent at least a portion of the cooking surface, the remote solar heat collector further being angled with respect to the cooking surface so as to maximise capture of sunlight and retention of heat. 20 Preferably, the remote heat collector is angled with respect to the cooking surface so as to maximise capture of sunlight and retention of heat. Still preferably, the cooking surface is provided in the form of a second heat collector. Still more preferably, the second heat collector extends from the 'remote heat 25 collector.
-5 Still more preferably, the second heat collector extends from the remote heat collector. A third heat collector is preferably arranged so as to be substantially perpendicular to the second heat collector. 5 Preferably, the third heat collector forms a rear wall extending up from the second heat collector. More preferably, the remote, second and third heat collectors are integrally formed. Preferably, side walls extend along the length of the secondary heat collector to 10 connect with the rear wall or third heat collector, forming a cooking chamber. The side walls preferably comprise a front edge extending upwards at substantially the same angle relative to the cooking surface as the remote heat collector, terminating at an upper edge. Preferably, the side walls are also formed from heat collecting material. 15 Insulating material preferably extends along an external surface of the rear wall and side walls of the cooking chamber. Insulating material preferably extends along an internal surface of the remote heat collector. A double glazed glass door is preferably positioned over the remote heat collector 20 and/or the cooking surface. Preferably, the heat transfer passage is formed by a space between the glass of the door covering the heat collector and the remote heat collector.
-6 Alternatively, the heat transfer passage can extend along the length of the internal surface of the remote heat collector. Preferably, a seal prevents the door from coming into direct contact with the remote heat collector, cooking surface and/or the third heat collector. 5 Preferably, the double glazed glass door comprises a frame of a material other than glass to minimise damage to the door. The material may comprise one or more of metal or wood. When closed, the door of the remote heat collector and the second heat collector enables the cooking chamber to be enclosed, like an oven. 10 Preferably, at least one reflector is used to direct heat in the form of sunlight onto the or each heat collector. Preferably, the at least one reflector is hingedly connected to the, or each door frame. The at least one reflector preferably comprises either a silver or mirrored reflective 15 surface. Still preferably, the position or angle of the at least one reflector is adjustable. The at least one reflector can preferably be used as a cover for the, or each door. Preferably, the cooking device further comprises an electrical heating element located within the heat transfer passage, beneath the cooking surface. 20 A fire chamber is preferably located beneath the heating element. Preferably, the fire chamber is in the form of an insulated box having an access door at its rear, and at least one air vent, and at least one exhaust vent.
-7 Preferably, the cooking device is encased in an outer casing which extends from a collector seat of the or each heat collector, encasing the heating element, fire chamber and insulation, terminating at the access door to the fire chamber. The double glazed glass door covering each heat collector is preferably hingeably 5 connected to the outer casing. Preferably, the cooking device comprises wheels so that it's position can be readily altered. Preferably, the or each heat collector comprises a sheet of metal painted black. More preferably, the or each heat collector is formed from a sheet of zinc and 10 aluminium alloy, which has been painted black. Still preferably, the, or each heat collector is formed from copper or aluminium, painted black. Brief Description of the Drawings The present invention will now be described, by way of example only, with 15 reference to a first and second embodiment thereof and the accompanying drawings, in which: Figure 1 is a cross sectional view of a cooking device in accordance with a first embodiment of the present invention; Figure 2 is a perspective view of the cooking device of Figure 1, showing 20 the remote heat collector and the cooking chamber; and Figure 3 is a further side view of a cooking device of Figure 1, showing the doors in place; - 8 Figure 4 is a cross sectional view of a cooking device in accordance with a second embodiment of the present invention. Best Mode(s) for Carrying Out the Invention In Figures 1 to 3 there is shown a cooking device 10 in accordance with a first 5 embodiment of the present invention, the cooking device 10 comprising a cooking surface 12, a remote heat collector 14 and a heat transfer passage 16. The remote heat collector 14 is arranged so as to be, at least in part, remote relative to the cooking surface 12. The heat transfer passage 16 is adjacent to the remote heat collector 14 and 10 extends beneath the remote heat collector 14 to a point adjacent to the cooking surface 12. The heat transfer passage 16 contains air which becomes heated by the remote heat collector 14. As this air is heated it rises up the passage to the cooking surface 12, aiding to heat the cooking surface 12. The heat transfer passage 16 also extends beneath the cooking surface 12 to facilitate substantially 15 uniform heating. Beneath the heat transfer passage 16 there is located insulating material 18 in the form of, for example, insulation batts, or bricks. The cooking surface 12 is provided in the form of a second heat collector, for example it is an extension of the remote heat collector 14. A third heat collector 20 forms a rear wall adjacent to the cooking surface 12, for example the third heat 20 collector 20 is substantially perpendicular to the cooking surface 12. Side walls 22 extend along the length of the cooking surface 12 to connect with the third heat collector 20, thereby forming a cooking chamber 24, as depicted in Figure 2. The side walls 22 comprise a front edge 26 that extends upwards at substantially the same angle as, and in line with, the remote heat collector, terminating at an upper 25 edge 28. The side walls 22 are also formed from heat collecting material and a layer of insulating material 27 extends along the surface of the side walls 22 and third cooking chamber 20, which is external to the cooking chamber 24, as depicted in Figure 2.
-9 The remote heat collector 14, cooking surface 12 and third heat collector 20 are all integrally formed. For example, each is formed from a single sheet of heat collecting material. Heat collecting material can comprise a sheet of metal painted black, for example a sheet of zinc/aluminium alloy, or copper or 5 aluminium. The remote heat collector 14 is angled relative to the cooking surface 12 so as to maximise the capture of sunlight regardless of the time of day. A first reflector 30 and a second reflector 32 can be positioned so that sunlight can be concentrated onto each of the remote heat collector 14 and cooking surface 12. The reflector 10 30 is, for example, hingedly connected to the cooking device 10 at a first end 33, and its position can be altered by an adjustable chain 34, or rope from which a remote end 35 of the reflector is suspended. The second reflector 32 is, for example, pivotably connected to the cooking device 10, with its position being altered by movement about the pivot. The reflectors 30 and 32 are formed from 15 reflective material, for example each comprises a silver or mirrored surface. The cooking device 10 further comprises an electrical heating element 36 to supplement the heat provided by the heat collectors 14, 12 and 20, as required. The heating element 36 is located within the heat transfer passage 16, below the cooking surface 12 and it connects with a thermostat 38, which is located on an 20 external surface of the cooking device, as depicted in Figure 2. The cooking device 10 still further comprises a fire chamber 40, located beneath the electrical heating element 36. The fire chamber 40 is provided in the form of an insulated box, having an insulated access door 42 at its rear, an air vent 44 to assist combustion and at least one exhaust vent 46. The insulating material 25 includes, for example, bricks to insulate the fire chamber 40 and fibreglass batts to insulate the access door 42. The air vent 44 is located at the base of the fire chamber 40, and is fitted with a baffle to restrict air movement and retain ash. A fire grate 48 is located above the air vent 44. The at least one exhaust vent 46 has a chimney in the form of a conduit 50 that extends outwards and upwards, as - 10 depicted in Figures 2 and 3, of the cooking device, to direct smoke and exhaust gases to atmosphere. The conduit 50 extends to a height, for example, well above head height of a user. The conduit 50 is also detachable and is fitted internally with an electric fan 52, which is powered by, for example, a photovoltaic 5 cell connected externally to the cooking device. In Figure 3 there is shown a cooking device 10, with first and second double glazed glass doors 54 and 56 respectively, covering each of the remote heat collector 14 and the cooking chamber 24. The doors 54 and 56 further comprise a frame 58 formed from a material other than glass, for example wood or metal. 10 The doors 54 and 56 are hingedly connected to the cooking device. When closed, the doors 54 and 56 aid heat retention, and enable the cooking chamber 24 to act in the form of an oven. However, the doors 54 and 56 can be opened to allow access to the heat collectors 14, 12 and 20, and in particular the cooking chamber 24. 15 The remote heat collector 14, the cooking surface 12 and the third heat collector 20 are all retained by a collector seat 60 which extends along the perimeter of the heat collectors 14, 12 and 20. The collector seat 60 secures the heat collectors 14, 12 and 20 to the cooking device 10 and also aids to insulate the edge of the heat collectors 14, 12 and 20. A seal 62 extends along the top of the collector 20 seat 60 so as to form a seal between the doors 54 and 56 and the collector seat 60. Both the seal 62 and the collector seat 60 prevent any part of the heat collectors 14, 12 and 20 from coming into direct contact with the doors 54 and 56. The reflectors 30 and 32 shown in Figure 1 can be hinged directly to the door frames 58 and the reflectors 30 and 32 can be used as a cover for the doors 54 25 and 56 for weather protection when not in use, and to aid heat retention. In Figure 4 there is shown a second embodiment of a cooking device 70 of the present invention. Like numbers depict like features as disclosed in Figures 1 to 3. The cooking device 70 has a heat transfer passage 72 extending along an - 11 upper side of the remote heat collector 14, between the glass panel of the door 54 and the surface of the remote heat collector 14. The small volume of air that is trapped within the heat transfer passage 72 is heated quickly by the sun and heat is quickly transferred up the length of the remote heat collector 14 to the cooking 5 surface 12. The internal surface of the heat collector 14 is in contact with insulating material 74 for example, fibreglass batts, which enables the heat collector 14 to retain heat for longer and maintain a higher temperature. This insulating material 76 extends along the length of the internal surface of the heat collector 14 and may be a different type of material used as the insulating material 10 18. Alternatively, the insulating materials 76 and 18 may be of the same composition. A second heat transfer passage 78 extends below the cooking surface 12. The second heat transfer passage 78 also houses the heating element 36. It is understood that the substantially small volume of the heat transfer passage 15 16 and/or 72 relative to the surface area of at least the remote heat collector 14, enables the cooking device 10 to achieve a desired temperature at a faster rate when compared to cooking devices of the prior art. This is because the volume to surface area ratio is much smaller in the cooking device 10 and 70 of the present invention when compared with, for example, the box cookers of the prior art. That 20 is, the surface area of the remote heat collector 14 and/or the cooking surface 12 can be increased with relatively small changes in volume of the heat transfer passage 16 and/or 72. Increasing the size of the heat collector in a conventional box cooker means the size of the entire box must increase, thereby resulting in a substantial increase in the volume of air within the box which also needs to be 25 heated. It is envisaged that the use of the heat transfer passage 16 and/or 72, together with the remote heat collector 14 of a larger than average size, enables the cooking device 10 and 70 of the present invention to achieve higher temperatures than would normally be achieved by conventional solar cookers. For example, the -12 heat collector 14 has been known to achieve temperatures as high as about 2050C, with average annual temperature of about 1690C. It is further envisaged that in addition to the electrical heating element 36 and the fire chamber 40, the cooking device 10 and 70 may also utilise gas as a heat 5 generating energy source when solar energy is unavailable. The doors 54 and 56 may be fitted with door stays, which hold the doors in the open position, for example, to allow ease of access to the cooking chamber. It further envisaged that the cooking device 10 or 70 may be located on a trolley or comprise a base with wheels as depicted in Figures 1, 2 and 3 so that its 10 position can be altered to ensure that the remote heat collector 14 has the greatest exposure to the sun. It is understood that the remote heat collector 14 may not necessarily be in direct connection or contact with the cooking surface. It is still further envisaged that the cooking device 10 is covered in a casing for 15 aesthetic purposes. The doors 54 and 56 may also be directly hinged to this casing. Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.