GB2204676A

GB2204676A - Cooking hobs

Info

Publication number: GB2204676A
Application number: GB08719096A
Authority: GB
Inventors: Gunter Krohn
Original assignee: Cramer GmbH and Co KG
Current assignee: Cramer GmbH and Co KG
Priority date: 1987-05-09
Filing date: 1987-08-12
Publication date: 1988-11-16
Anticipated expiration: 2007-08-12
Also published as: GB2204676B; DE3715540A1; DE3715540C2; FR2614975A1; FR2614975B1; GB8719096D0

Description

- 1 2 2 0 l.' In c "' 7.8 V COOKING STOVE WITH RADIANT GAS BURNERS AND

VITREOUS CERAMIC COVERPLATEr E. G.p FOR CARAVANS This invention relates to a cooking stove, more particularly - but not exclusively - for a caravan, having a f ramey a false bottom with a fume extraction channel on its underside. a plurality of radiant gas burners, a thermal insulating layer of refractory material lying on the false bottom, and a coverplate of vitreous ceramic, in which the radiant gas burners are set in seating apertures in the false bottom,, the thermal insulating layer has apertures for the radiant gas burners and channel- forming fume escape apertures leading therefrom, the coverplate is attached to the frame,, lies on the thermal insulating layer and thereby provides top cover for the channel-forming fume escape apertures#, the fume escape apertures lead to the mouth of the fume extraction channel. and the fume extraction channel terminates at a chimney connection union. It is self-evident that the chimney connection union can be connected to a ductr for example a corrugated flue ducty which opens into a chimney or releases the fumes directly. The distance between the surfaces of the radiant gas burners and the coverplate is several millimetres, up to about 10 mm.

In a known cooking stove of this type the -fume escape apertures are connected to a common f ume extraction channel having no internal obstructions and of a cross-section such that the fumes can be extracted when all the radiant gas burners are consuming the maximum amounts of fuel gas.

Neverthelessr problems arise when the radiant gas burners are operated simulataneously at very different settings. Th e radiant gas burner set at a low gas/air mixture flow rate produces an unsteady and unstable flame, which from time to time will suddenly and unexpectedly go out. It is known in fact that unsteadiness at low gas/air mixture flow rates can be counteracted by dividing the burner into combustion zones, each supplied by a separate gas/air mixture nozzle (DE-PS 24 40 701). However. despite this flame stabilisation the problem referred to still arises when a plurality of radiant gas burners are operated simultaneously at very different settings.

The object of the invention is to provide a cooking stove of the type described with means whereby a radiant gas burner can be adjusted to a low heat output when another burner or other burners in the same stove are operated at a high heat ouput and supplied with a large flow rate of gas/air mi xt ur e.

According to the present invention, the f ume extraction channel has the same number of compartments as there are radiant gas burners, each compartment serves a single fume escape aperture, and the chimney connection union overlaps with the cross-section of each compartment.

The invention arises from the realisation that when the fume extraction channel has no internal obstructions, the flame from the radiant gas burner on a low setting is choked by fumes from another burner or other burners set at high gas/air mixture flow rates. This applies particularly to a cooking stove installed in a caravan since in this case the suction effect at the chimney connection union is frequently inadequate. The problem can surprisingly be eliminated without altering the external dimensions of the fume extraction channel by com par tmentali sing the fume extraction channel in conformity with the invention. The significant features of the invention are that every compartment terminates at the chimney connection union and that the suction effect is equally active in every compartment.

The preferred constructive embodiment of the invention provides that the fume extraction channel is formed from sheet with a trough-shaped jacket element, endf aces and a rectangular entry port,, at least one compartment-forming separating sheet is set horizontally in the f ume extraction channelt being extended over the breadth of the f ume extraction channel but kept shorter than the length of the f ume extraction channels, while the separating sheet abuts on one endf ace of the fume extraction channel and is bent up at the opposite end so as to terminate flush with the rim of the e'ntry port. This embodiment is highly advantageous-in both performance and manufacturing aspects. As regards perf ormance, the advantage consists primarily in that the entry port connecting the fume extraction channel to the fume escape apertures in the thermal insulating layer can be made quite broad,, to conform to the external dimensions of the fume extraction channel, so that pressure losses which would impair performance can be avoided even when the fume escape channels in the thermal insulating layer are comparatively narrow. AS regards manufacturingi the advantage consists primarily in that two or more separating sheets can be inserted one over another into the open-topped trough with ease, and then be secured to the jacket element by welding or brazing. In the preferred embodiment of the invention, the chimney connection union is disposed on the endface of the fume extraction channel and overlaps the cross-section of each of the compartments. moreover, no complicated means are required in order to seal the compartments. For preference, the false bottom is provided with an aperture matching the entry port to the fume extraction channeli And the thermal insulating layer consists of mineral wool, which extends over the open-topped fume extraction channel, while the bent-up end of each separating sheet abuts as a sealing lip on the thermal insulating layer. It is self-evident that a plurality of compartments can be sealed against the thermal insulating layer in this way. Since according to the invention the false bottom can also be designed with an aperture matching the entry port to the fume extraction channel,, it is within the scope of the invention to combine the fume extraction channel and the false bottom to form a single component. This contributes further to a reduction in manufacturing co st S.

The accruing advantages are to be seen above all in the improved controllability of radiant gas burners. The design of the cooking stove of the invention is such that one pan can be kept warm on a low gas flame at the same time as another or other radiant gas burners is or are set at a high flame, for boiling or frying for example. This improvement in the versatility of the stove has been attained without c altering its external geometry. This is important above all for use in caravansi, where compactness is a special advantage.

An embodiment of the invention will now be described, purely by way of example, with reference to the accompanying diagrammatic drawings, in which:- Figure I is a persepective view of the cooking stove, with the coverplate removed and the stove partly sectioned; and Figure 2 is a corresponding view of the false bottom and attached fume extraction channel.

The cooking stove shown in the drawings is destined specifically for the cooking alcove in a caravan. Its basic const r ucti on com. pr i se s a f ram e 1, a f al se bottom 2 with a f um e extraction channel 3 on its underside, a thermal insulating layer 4 of mineral wool lyingon the false bottom, a plurality of radiant gas burners 5j, and a coverplate 6 of vitreous ceramic. The frame 11, the false bottom 2 and thd fume extraction channel 3 are made from sheet material. The f al se bottom 2 has seating apertures 7 in which the radiant gas burners 5 are set. The thermal insulating layer 4 is designed with apertures 8 for the radiant gas burners 5 and channel-forming fume escape apertures 9 leading therefrom. The coverplate 6 is attached to the frame 1 and lies on the thermal insulating layer 4. This provides top cover for the apertures 8 and the channel-forming fume escape apertures 9. It is within the scope of the invention to widen the gas escape apertures 9 locally to provide simmering zones, as shown at 9A.

On comparing Figures 1 and 2, it will be seen that the fume extraction channel 3 has the same number of compartments 10 as there are radiant gas burners 59, each compartment 10 being connected to a single gas escape aperture g. Furthermore, the f ume extraction channel 3 has a troughshaped jacket element 11, endfaces 12a# 12b and a rectangular entry port 13. A compartment-forming separating sheet 14 is set horizontally in the f ume extraction channel 3, being extended over the breadth B of the fume extraction channel 3 but kept shorter than the length of f ume extraction channel 3. The separating sheet 14 abuts on one endface 12a of the fume extraction channel 3 and is bent up at the other end 15 so as to terminate flush with the rim 16 of the entry port 13. Moreover, a chimney connection union 17, which overlaps with the cross-section of each compartment 109, will be seen at the endface 12a where the separating sheet 14 terminates# and can be conected to a corrugated flue pipe (not shown). The thermal insulating layer 4 of mineral wool extends over the open-topped fume extraction channel 3P while the bent-up end 15 of the separating sheet 14 abuts as a sealing lip on the thermal insulating layer 4. It is obvious that additional compartments can be formed and sealed in the same way. it is within the scope of the invention to combine the f ume extraction channel 3 and the f al se bottom 2 to f orm a single component, or to f orm them separately and provide the f al se bottom with an aperture matching the entry port 13 to the fume extraction channel.

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Claims

1. A cooking st-ove having a frame, a false bottom with a fume extraction channel on its underside, a plurality of radiant gas burnersp a thermal insulating layer of refractory material lying on the false bottomy and a coverplate of vitreous ceramic#, in which the radiant gas burners are set in seating apertures in the false bottom# the thermal insulating layer has apertures for the radiant gas burners and channel-forming fume escape apertures leading theref rom, the coverplate is attached to the frame, lies on the thermal insulating layer and thereby provides top cover for the channel-forming fume escape apertures,, the fume escape apertures lead to the mouth of the fume extraction channel, and the fume extraction channel terminates at a chimney connection uniont and in which the fume extraction channel has the same number of compartments as there are radiant gas burners, each compartment serves a single fume escape aperture, and the chimney connection union overlapz with the crosssection of each compartment.

2. A cooking stove as in Claim 1, wherein the fume extraction channel is formed from sheet with a trough-shaped jacket element, endfaces and a rectangular entry port, at least one compartment-forming separating sheet is set horizontally in the f ume extraction channel, being extended over the breadth of the f ume e xtraction channel but kept shorter than the length of the fume extraction channel,, while the separating sheet abuts on one endf ace of the f ume extraction channel and is bent up at the opposite end so as to terminate flush with the rim of the entry port.

3. A cooking stove as in Claim 2r wherein the chimney connection union is disposed on the endface of the f ume extraction channel and communicates with all the compartments bounded by a separating sheet.

4. A cooking stove as in Claim 2 or Claim 3, wherein the false bottom has an aperture matching the entry port to the fume extraction channel#, and the thermal insulating layer consists of mineral wood,, which extends over the open-topped f ume extraction channelf while the bent-up end of the separating sheet abuts as a sealing lip on the thermal insulating layer.

5. A cooking stove as in Claim 2 or Claim 3, wherein the fume extraction channel and the false bottom are combined to form a single component.

6. A cooking stove substantially as hereinbefore described with reference to the accompanying drawings.

S Published 1988 at The Patent Office, State House, 66.71 High Holborn, London WCIR 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3F.D. Printed by Multiplex techniques ltd, St Mary CraY, Kent. Con- 1/87.

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