GB2345128A - Gas oven - Google Patents

Abstract

The gas oven has heat supplied to an oven cavity (<B>202</B>) by means of a burning gas flame from a gas burner (<B>222</B>). Nozzles (<B>223</B>) are provided for directing a jet of air towards the burning flame to facilitate the distribution of heat within the cavity. A centrifugal fan (<B>205</B>) supplies air under pressure to the nozzles (<B>223</B>), and to cooling air passages (<B>208, 210, 212</B>). A deflector (<B>224</B>) causes mixing of hot and cool air within cavity (<B>202</B>).

Description

Gas Oven The present invention relates to a gas oven in which heat is supplied to an oven cavity by means of a buming gas flame.

An oven cavity A1 is shown in Figure A, having a gas bumer A2 configured to heat the oven cavity A1 to an appropriate cooking temperature.

A guard plate A3 is positioned in front of bumer A2 so as to present a more aesthetic appearance when a door A4 is opened and to prevent mechanical damage to the gas bumer A2 when cooking equipment is located within the cavity A1.

When in operation, air surrounding the gas bumer A2 is heated thereby causing it to ascend as indicated by arrow A5. Cooler air is then introduced towards the bumer A2 thereby continuing to apply force to the previously heated air, resulting in a substantially circular convection effect.

Thus, air ascends above the bumer A2, traverses across the top of the oven cavity towards the door A4, descends towards the bottom of the oven cavity and is then brought back towards the bumer A2 for it to be heated again, thereby maintaining the circulation.

An effect of the convection airflow shown in Figure A is that temperature differentials are created within the oven cavity which may result in foodstuffs contained within the oven cavity being cooked in a non-uniform way. In particular, the region designated A6 would become substantially warmer than the region identifie as A7.

It is known to include rotating fans within the oven cavity A1, thereby introducing a turbulent airflow within the cavity to ensure that the hot air in the region A6 is mixed with the relatively cooler air in the region A7. This in tum results in a more homogenous temperature distribution within the cavity, ensuring that foodstuffs are cooked evenly. In addition, the totality of heat received by the foodstuffs is increased overall which in tum reduces total cooking time.

A problem with the known approach of introducing a fan into the cooking cavity is that the overall mechanical complexity of the configuration is increased, thereby increasing the overall cost, increasing the number of components that may fail and introducing new problems in terms of keeping all of the mechanically operable components clean and reliable. The designers of ovens of this type are therefore presented with a problem in terms of how to produce a more uniform heat distribution within the oven cavity or cavities while minimising additional mechanical complexity.

According to a first aspect of the present invention, there is provided a gas oven in which heat is supplied to an oven cavity by means of a buming gas flame, comprising means for directing a jet of air towards said buming flame to facilitate the distribution of heat within said cavity.

Preferably, positive air pressure is received from a plenum chamber and said plenum chamber may be located behind the oven cavity. In a preferred embodiment, the plenum chamber receives air from atmosphere by means of a centrifugal fan and the plenum chamber may also be used to provide a supply of cooling air.

According to a second aspect of the present invention, there is provided a method of distributing heat within an oven cavity, comprising the steps of buming gas in the form of a heating flame; and directing the jet of air towards said buming flame, thereby facilitating the distribution of heat within said cavity.

The invention will now be described by way of example only, with reference to the previously identified drawings, in which: Figure 1 shows a gas cooking appliance; Figure 2 shows a cross-section of the cooking appliance shown in Figure 1; Figure 3 details a gas bumer of the type shown in Figure 2 and details a first embodiment of the present invention; Figure 4 details a second embodiment of the present invention; and Figure 5 details a third embodiment of the present invention.

A gas cooking appliance is shown in Figure 1, having a plurality of gas bumers 101, a first oven 102 and a second oven 103. The first oven 102 is of known design and includes facilities allowing it to be used as a grill. The lower oven 103 embodies the present invention and is designed to provide enhanced oven cooking by maintaining a substantially even distribution of heat within the oven cavity.

A cross section of the oven, viewed from the side, is shown in Figure 2. The arrangement of the cooking appliance is substantially similar to that described in United Kingdom Patent number 2 255 632 B. Two oven cavities 201,202 are provided, with cavity 201 being disposed above cavity 202. At the rear of both oven cavities there is provided a plenum chamber 203 with an air inlet 204 disposed to co-operate with a centrifugal fan 205; the direction of inward airflow being indicated by arrows 206.

Fan 206 draws air from around the cooker chassis as indicated by arrows 206 and then discharges this air into the plenum chamber 203 at positive pressure. Fan 205 is driven by an electric motor which may be an integral part of the fan. The motor has a control circuit that brings it into use when one or other of the ovens is activated. Energisation of the fan motor may take place immediately upon activation of an oven or a predetermined time delay may be introduced before energisation of the motor takes place.

Outlets 207 in the top wall of the plenum chamber 203 allow air from the plenum chamber to enter an outlet duct 208 above the upper oven cavity 201. Air flowing in duct 208 passes around a cooker control panel and thereby cools it. This cooling air leaves duct 208 to atmosphere via a series of outlet holes spaced across the front of the cover and above the control panel.

Second outlets 209 allow air from the plenum chamber 203 to pass into a second duct 210 positioned between the upper oven cavity 201 and the lower oven cavity 202. Duct 210 terminates in a series of outlet holes spaced across the front of the cover and aligned with the lower open end of a passageway between inner and outer door panels of the upper oven cavity door. Consequently, air leaves said passageway to atmosphere via the upper end of the door adjacent to the control panel and a scoop may be fitted to assist the flow of air from the duct into the passageway.

A third outlet 211 allows air from the plenum chamber 203 to enter a third outlet duct 212 beneath the lower oven cavity 202. Duct 212 terminates in a series of outlet holes 213 spaced across the front of the cooker and aligned with the lower open end of a passageway 214 between an inner door panel and an outer door panel of the lower oven cavity door. Consequently, air leaves passageway 214 at the upper end of the door and the flow of air from duct 212 may be assisted by the presence of a scoop.

The flow of air through the passageway, such as the lower door passageway 214, maintains the temperature of the outer door panels at a safe level, thereby minimising the risk of injury to anyone who may inadvertently touch the panel.

It is also known, as disclosed by the aforesaid patent, for combustion air required by a gas bumer present within the oven to receive at least some of its combustion air from the plenum chamber 203. The present invention takes this notion a stage further by making further use of the positive air pressure provided by the plenum chamber. Thus, in addition to ensuring complete and efficient combustion of gas within an oven cavity, positive air pressure is also used to stimulate the distribution of heat within the oven cavity in order to ensure that foodstuffs contained within the oven cavity are cooked evenly.

In particular, means are provided for directing a jet of air towards the buming flame so as to facilitate the distribution of heat within the cavity.

Upper oven cavity 201 includes a conventional gas bumer 221. Lower oven cavity 202 includes a gas burner 222 embodying the present invention.

Means are provided in the form of a noale 223 for directing a jet of air from the plenum chamber 203 towards a buming flame emanating from gas bumer 222. Air heated in the vicinity of the flame emitted by bumer 222 is directed towards a streamlined air deflector 224, thereby causing an enhanced mixing of hot and cool air within cavity 202 without introducing unnecessary turbulence.

In response to air emitted from nozzle 223 and under the influence of deflector 224, hot air is pushed forward in the direction of arrows 225. Once deflected in this way, the hot air will ascend evenly through the oven cavity, mixing with descending cooler air thereby significantly improving the distribution of the heating effect within the cavity, when compared to the configuration detailed in Figure A.

Gas bumer 222 extends linearly across the width of the back of the oven, as detailed in Figure 3. Gas bums behind deflector 224 and air is pushed in direction of arrows 301 in response to air received from two nozzles 223A and 223B. The nature of the air emitted by these nozzles is controlled by means of adjusting the nozzle size and adjusting the level of pressure generated within the plenum chamber 203. It should be noted that the flow of air is primarily intended to direct heated air in the vicinity of the gas flame and not to impact directly on the flame itself. However, it should be appreciated that the presence of air in the vicinity of the flame also assists with flame combustion, with care being taken not to reduce the temperature of the flame sufficiently so as to cause the flame to be extinguished.

An alternative embodiment is shown in Figure 4, having a gas bumer 423 substantially similar to that shown in Figure 3 and a deflector 424 again substantially similar to that shown in Figure 3. Two gas nozzles 401 and 402 are provided but on in this embodiment the ends of the nozzles are extended linearly across the width of the area of interest thereby causing the air to be directed in a more uniform manner at a preferred displacement from the gas bumer 423. In this way, the flow of air remains more uniform across the entire width of the oven, again enhancing heat uniformity during the cooking operation.

A second alternative embodiment is shown in Figure 5. Again, gas bumer 523 and deflector 524 are of substantially similar constructions to those shown in Figure 3. However, in this embodiment two outlet orifices 501 and 502, communicating with plenum chamber 203, are connected to a common outlet nozzle 503 having a plurality of small outlet orifices 504. In this way, the flow of air towards the gas flame is maintained substantially uniform across its width.

Claims (17)

Claims

1. A gas oven in which heat is supplied to an oven cavity by means of a buming gas flame, comprising means for directing a jet of air towards said buming flame to facilitate the distribution of heat within said cavity.

2. An oven according to claim 1, wherein positive air pressure is received from a plenum chamber.

3. An oven according to claim 2, wherein said plenum chamber is located behind the oven cavity.

4. An oven according to claim 2 or claim 3, wherein said plenum chamber receives air from atmosphere by means of a centrifugal fan.

5. An oven according to any of claims 2 to 4, wherein said plenum chamber also provides a supply of cooling air.

6. A gas oven according to claim 1, wherein a plurality of air directing means are provided.

7. An oven according to claim 1, wherein each air directing means includes an elongated exit nozzle.

8. An oven according to claim 1, wherein said means for directing a jet of air towards said burning flame comprises an elongate outlet nozzle extending for substantially the full width of the gas bumer.

9. An oven according to claim 8, wherein said elongate outlet nozzle receives air from a plurality of inlets.

10. An oven according to claim 9, wherein said plurality of gas inlets are received from a plenum chamber.

11. A method of distributing heat within an oven cavity, comprising the steps of buming gas in the form of a heating flame; and directing a jet of air towards said buming flame, thereby facilitating the distribution of heat within said cavity.

12. A method according to claim 11, wherein positive air pressure is received from a plenum chamber.

13. A method according to claim 12, wherein said plenum chamber is located behind the oven cavity.

14. An oven according to claim 12 or claim 13, wherein said plenum chamber receives air from atmosphere by means of a centrifugal fan.

15. A method according to any of claims 12 to 14, wherein said plenum chamber also provides a supply of cooling air.

16. A gas oven substantially as herein described with reference to any of Figures 1 to 3.

17. A method of distributing heat within an oven cavity substantially as herein described with reference to Figures 1 to 3.