GAS HEATING APPLIANCE

Abstract: The present invention relates to a gas burner particularly suited for gas heating applicances for cooking food. In particular the present invention comprises a generally circular moulded body (100) including gases inlet (106) and an internal cavity (114). The internal cavity (114) is covered by a substantially transparent glass cap (108), which also bounds on the gas outlets (116). In this fashion, due to the transparency of the glass cap (108) at low flame improve controllability and safety are achieved by visual feedback of the flame size.

Description: GA S HEATING APPLIANCE TECHNICAL FIELD This invention relates to a substantially transparent cap for a heating appliance particularly though not solely for use as a gas burner cooktop. BACKGROUND ART There are a number of methods known in the art for providing heating in a cook top. One of the preferred methods is using a gas burner due to the ability to deliver high levels of heating when required and also relatively fine levels of control. It is typical of such gas burners that the finest levels of control will be desired at the low end of the output range. Various methods have been postulated in order to implement fine control in the lower output range. For example, US 5,009,393 discloses a gas turn down valve with a relatively gradual control characteristic which provides a greater level of control especially at lower outputs compared to traditional gas valves. In a further improvement described in Korean Patent 9,208,198 an electromechanical actuator is used to rotate the gas valve in order to achieve fine levels of control across the entire range of output. However, while these prior art systems do provide improved control, it would be desirable to have a simple system which by way of visual feedback allowed fine control at low levels of burner output. DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a gas burner which goes someway to achieving the above mentioned desiderata or which will at least give the public a useful choice. Accordingly in a first aspect the present invention consists in gas burner comprising: a body portion including a gas inlet and an open inner cavity in fluid communication with said gas inlet, a substantially transparent cover means adapted to engage or attach to said body portion and thereby substantially cover said inner cavity and, a plurality of gas outlets substantially adjacent the boundary formed between said cover means and said body portion and in fluid communication with said inner cavity. To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. BRIEF DESCRIPTION OF THE DRAWINGS One preferred form of the present invention will now be described with reference to the accompanying drawings in which; Figure 1 is a cut-away view of the gas burner according to the preferred embodiment of the present invention, Figure 2 is a plan view of the body portion according to the preferred embodiment of the present invention, Figure 3 is a perspective view of the substantially transparent glass burner cap according to the preferred embodiment of the present invention, Figure 4 is a plan view of the gas burner at a low flame setting according to the preferred embodiment of the present invention, Figure 5 is a plan view of the gas burner on a high flame setting according to the preferred embodiment of the present invention, Figure 6 is a side view of the wok-style burner, and Figure 7 is a plan view of the wok-style burner. BEST MODE FOR CARRYING OUT THE INVENTION Referring now to Figure 1 and 2 a gas burner is shown according to the referred embodiment of the present invention. The gas burner is formed of a body portion 100 including a gas inlet 102 and an internal cavity 104 such that the gas flows from the gas supply 106 into the internal cavity 104. The top of the internal cavity 104 is closed off with a substantially transparent glass cap 108 which attaches overtop of and overhangs the body portion 100. The gas then flows from the internal cavity out through outlet channels 112 formed on the top face 114 of the body portion 100 to the outlet ports 116 where the gas is ignited and heats the cooking vessel (not shown). Referring to Figure 3 w e see the burner cap 108 in more detail. The cap 108 may optionally include a central co le 150 designed to fit down the internal cavity (104, Figure 1) of the body portion (100, Figure 1). On the underside is a flat annular face 152 designed to sit firmly upon the upper face (114, Figure 1) of the body portion. The cap 108 also includes an outer flange 156, which overhangs the body portion (100, Figure 1). The outer flange 156 is designed to diffuse the flames before they contact the heating vessel. The glass cap itself is composed of a typical ceramic type glass. Such glass is designed with a significant resistance to thermal shock and high contact temperature, such as expected when exposed to a gas fuelled flame. A Borosilicate based glass would be particularly appropriate. The present invention is shown in use in Figures 4 to 5. At low flame, seen in Figure 4 the actual flame 200 is only seen by virtue of the cap 202 being transparent. At high flame the flames 204 extent past the outer flange 206, and are evenly distributed around the circumference. By virtue of the flames being visible at low flame more accurate control and greater safety is possible over prior art burners. A further improvement would be to mould designs or text onto the underside of the glass cap. This would allow the top face to be easily cleaned. The manufacturers name or other designs would then be visible from above. It will be appreciated that by providing a low thermally conductive material such as the glass cap as opposed to the conventional cast iron, or highly thermally conductive caps, that the performance of the gas burner may improve. At low flame with a highly thermally conductive cap there is the potential for "quelching" or partial extinction of the flame. This results in partial combustion with the by-product of higher CO emissions. With the low thermal conductivity of the glass cap according to the present invention, the potential for "quelching" is much reduced. Therefore the burning is more controlled, more efficient and the CO emissions are potentially reduced, especially at low outputs. Another advantage to the present invention relates to the fact that with glass or other transparent thermally retardant material as the burner cap, the need for a separate coating operation of the burner cap is eliminated. Traditionally with cast iron or cast aluminium burner caps, due to the fact that they are constantly in contact with combusting illustrated in a configuration for a wok-style burner. In this case the main body 210 is substantially composed as described in the preceeding embodiments, having outlets 212 on the outer periphery 214 of a raised portion 211 inset from the edge of the main body 210. However rather than having the inner cavity completely open, the main body includes a covered centre section 216 extending approximately 2/3 the radius of the outer periphery 214 to form an inner periphery 218 to the raised portion. Included on the inner periphery are a further set of outlet ports 220 to provide flames towards the centre of the wok to provide more even heating and to ensure that the centre of the wok is sufficiently hot as is often desirable when cooking with a wok. Also shown in Figures 6 and 7 is the trivet plate 222 which supports the wok (not shown) above the flames. The trivet 222 supports the wok about an annular path 224 which allow the wok (not shown) to be readily moved and removed, ensuring adequate flame contact to the underside of the wok and minimal flame contact on the trivet. The substantially transparent glass cap 226 as described in the previous embodiments is in this case embodied in an annular ring with tapered portions (or rounded edges) at its inner 228 and outer 230 peripheries. Again the cap 226 is composed of a similar material and at low flame ensures full visibility of the flame. At high flame as shown in Figure 6, the flames can be seen both inwardly and outwardly of the raised portion 211. It will be readily apparent to one skilled in the art the advantages to the system described above and as defined in the appended claims.

Claims: CLAIMS 1. A gas burner comprising: a body portion including a gas inlet and an open inner cavity in fluid communication with said gas inlet, a substantially transparent cover means adapted to engage or attach to said body portion and thereby substantially cover said inner cavity and, a plurality of gas outlets substantially adjacent the boundary formed between said cover means and said body portion and in fluid communication with said inner cavity. 2. A gas burner as claimed in claim 1 wherein said cover means is substantially composed of glass. 3. A gas burner as claimed in claim 1 wherein said cover means is composed of a glass mixture with substantial resistance to thermal shock. 4. A gas burner as claimed in claim 1 wherein said cover means is composed of glass ceramic. 5. A gas burner as claimed in claim 1 wherein said cover means is composed of a silica based glass mixture. 6. A gas burner as claimed in claim 1 wherein said cover means in composed of a borosilicate glass mixture. 7. A gas burner as claimed in any one of the preceeding claims wherein said plurality of gas outlets comprises a number of channels formed in what is in use the upper face of said body portion, said channels running from the inner cavity of said body portion to the outer circumference of said body portion. 8. A gas burner as claimed in any one of claims 1 to 6 wherein said plurality of gas outlets comprises a number of channels formed in what is in use the lower face of said cover means, said channels running from (when said cover means is in place atop said body portion) the inner cavity of said body portion to the outer circumference of said body portion. 9. A gas burner as claimed in any one of claims 1 to 6 wherein said plurality of gas outlets comprise a plurality of holes in said body portion, extending from said inner cavity to the exterior. 10. A gas burner as claimed in any one of the preceeding claims wherein said cover means includes lettering or designs moulded into or printed onto what is in use the underside of said cover means. 11. A gas burner as claimed in any one of the preceeding claims wherein said body portion includes a centre portion and said inner cavity comprising an annular cavity around said centre portion, said plurality of gas outlets comprising inner outlets facing inwardly substantially toward the centre of said burner and outer outlets facing substantially outwardly of said burner, and said cover means comprising a substantially transparent annular ring substantially covering said annular cavity. 12. A gas burner as claimed in any one of the preceeding claims wherein said cover means including a tapered portion on the outer circumference thereof. 13. A gas burner substantially as herein described with reference to and as illustrated by the accompanying figures.

Inventors: BROWN SIMON DENZIL, BROWN, SIMON, DENZIL
Applicants: BROWN SIMON DENZIL, FISHER & PAYKEL, BROWN, SIMON, DENZIL, FISHER & PAYKEL LIMITED
Application year: 2000
Main classification: F24C3
IPC codes: F23D14, F24C3, F24C15