GB2197458A

GB2197458A - Fan-assisted gas-fired cooking oven

Info

Publication number: GB2197458A
Application number: GB08627058A
Authority: GB
Inventors: Graham Albert John Lake; David Gregson Young
Original assignee: Glynwed Consumer and Building Products Ltd
Current assignee: Glynwed Consumer and Building Products Ltd
Priority date: 1986-11-12
Filing date: 1986-11-12
Publication date: 1988-05-18
Anticipated expiration: 2006-11-12
Also published as: GB8627058D0; GB2197458B

Abstract

A gas burner (23) is provided above and towards the rear of the floor (12) of a cooking chamber (11) of a gas-fired oven (4). A fan chamber (35) housing a motor-driven fan (36) is positioned at or behind the cooking chamber and is operative to draw products of combustion from the burner (23), into the fan chamber (35) and circulate them back into the cooking chamber (11) from the rear of the cooking chamber by means of distribution outlets (44, 46, 46'). A cowl (43) surrounding the inlet (42) to the fan chamber (35) and a housing (27) and draught break (32) substantially surrounding the burner direct the products of he combustion to the inlet (42). Some distribution outlets (44) may be between an imperforate lower shelf (17') in the cooking chamber (11) and the floor (12) of the cooking chamber, the shelf (17') leading the products from the rear of the bottom of the cooking chamber (11) to the front of the underside of the shelf (17') in which region a deflector (45) provided on the door (8) of the oven (4) directs the products back over the top of the shelf. <IMAGE>

Description

SPECIFICATION Fan-assisted gas-fired cooking oven This invention relates to a fan-assisted gasfired cooking oven.

According to the present invention a fanassisted gas-fired cooking oven is provided having a cooking chamber above and towards the rear of a floor of which is a gas burner, and at or behind which cooking chamber there is a fan chamber in which a motor-driven fan is housed operative to draw products of combustion from the burner into the fan chamber and to circulate them back into the cooking chamber from the rear of that chamber by way of one or more distribution outlets opening from the fan chamber.

A cowl may be provided above the burner to direct the products of combustion from the burner into an inlet or inlets of the fan chamber. The cowl preferably extends across a substantial part of the width of the cooking chamber. The burner may be positioned behind a screen in the cooking chamber. The screen may form part of a housing around the burner inside the cooking chamber. Such a housing may be connected directly or indirectly to the inlet of the fan chamber. A draught break may be necessary between the burner and the inlet or inlets to reduce the effect of the fan on the performance of the burner. Aeration to control combusion conditions in the housing may be provided by, or be supplemented by, one or more air outlets opening, preferably upwardly, from the fan chamber into the housing behind the burner.

The distribution outlet is, or at least some of the outlets where there are several are, preferably positioned at or close to the floor at the rear of the cooking chamber. A shelf which is imperforate, or substantially imperforate, may be supported in the cooking chamber just above the level of the outlet or at least some of the outlets so that a duct is defined below the shelf which channels the products of combustion towards the front of the cooking chamber from the distribution outlet or outlets. A baffle may be provided, removably or as a fixture, at the front of the cooking chamber, conveniently on a door of the chamber, to direct the products back across the cooking chamber again. Where there are several distribution outlets there may also be outlets at upper and intermediate parts of the rear of the cooking chamber.

There may be one or more baffles in the fan chamber to assist distribution of the products to the distribution outlet or outlets, and preferably to straighten the flow of the products into the cooking chamber.

An exhaust outlet for the products to pass out of the cooking chamber after they have circulated in the chamber is conveniently positioned at or near the front of the roof of the chamber, and connects with a passage extending over the cooking chamber to a flue at the back of the oven. Thus the products impart heat to the roof of the chamber as they pass along the passage to the flue.

It is preferred that the distribution of the products from the fan chamber into the cooking chamber is entirely from the rear of the cooking chamber. There may be some distribution from the sides but distribution solely from the rear has the advantage that the width of the cooking chamber can be maximised in the oven, because then ducts do not have to be provided at the sides of the cooking chamber for the products to be taken to the sides from the fan chamber. The absence of such ducts, furthermore, enables a simpler oven construction to be achieved.

Because' the burner is above the floor of the cooking chamber the floor can be at a lower level than would be possible if the burner were to be positioned below the floor. Thus, the height of the cooking chamber may be increased, or in the case, for example, of the oven being incorporated in a cooker of waist height, since the floor can be at a lower level, a grill and a hob may be provided above the cooking chamber without the height of the chamber being unduly restricted. With the burner above the floor, it may be unnecessary for thermal insulation to be provided under the floor.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a simplified, partly-sectioned front view of a domestic cooker incorporating a fan-assisted gas-fired oven in accordance with the present invention, and Figure 2 is a vertical section through the oven on the line 2-2 of Figure 1.

The cooker is of waist height suitable for inclusion in a system of domestic kitchen units. It has a casing 1 supported on adjustable feet 2 and casters 3, and housed in the casing are a fan-assisted gas-fired cooking oven 4, a gas-fired grill 5 above the oven and a hob 6 above the grill having an arrangement of gas-fired burners 7. The oven and grill both have access doors 8 and 9 respectively. Controls for all of the hob, grill and oven burners are at a control panel 10 extending across the front of the hob 6.

The oven 4 has a cooking chamber 11 which is bounded by a floor panel 12, two opposite side panels 13, a rear panel 14 and roof panel 15, and is closed at the front by the oven door 8. A series of vertically spaced, horizontally extending groove formations 16 in the side panels 13 support removable shelves 17,17'. The bottom shelf 17' is imperforate.

There is an exhaust outlet 18 in the roof panel 15, Figure 2, near the front of the cook ing chamber 11 which opens into a passage 19 extending over the roof panel to a flue, not shown, at the back of the casing 1. Thermal insulation 20 is provided between the passage 19 and the grill 5.

Immediately in front of the rear panel 14 the floor panel 12 has a central raised portion 21, Figure 2, containing a rectangular opening 22 which extends transversely of the cooking chamber 11. In that opening 22, above the general level of the floor panel 12, an oven burner 23 is mounted together with an associated spark igniter 24, and flame failure device 24'. A gas supply pipe 25 extends to the burner 23 below the floor panel. A thermostat, not shown, feeds gas to the gas supply pipe 25 and has a temperature sensor in the upper part of the oven chamber.Supported on and sealed by a soft seal 26 to the raised portion 21 around the opening 22 is an upstanding housing 27 which has a front wall forming a screen 28 in front of the burner, and two side walls 29 which extend from the screen to the rear panel 14 beyond the ends of the burner and are sealed by soft seals 30 to the rear panel. Thus the burner is surrounded by the housing 27 and adjacent part of the rear panel which together define an open-topped burner chamber 31 containing the burner. An upper portion of the screen 28 is inclined rearwardly and upwardly over the burner to form a draught break 32 which is directed towards but spaced from the rear panel and partially restricts the top of the burner chamber 31. A viewing window 33 in the screen enables the burner to be seen from the front of the cooking chamber.

The rear panel 14 is detachably secured in front of a back wall 34 of the casing 1. Together the rear panel and back wall 34 define an enclosed fan chamber 35 in which a centrifugal fan 36 operates which is rotated about a horizontal axis normal to the rear panel and back wall. Screws 37 engaged with brackets 38 welded to the back wall 34 secure the rear panel in position on the back wall. A soft seal 39 fitted around the rear edge of a rearwardly extending peripheral flange 14' of the rear panel seals the panel to the back wall.

Long screws 40 retained by nuts 41 to the rear panel extend across the space between the panel and the back wall at intermediate positions to act as spacers which ensure that the rear panel is properly spaced from the back wall at all times, even if there should be some distortion of the rear panel, and will not be fouled by the fan 36.

The fan 36, which is driven by an electric motor, not shown, mounted inside a cover, not shown, behind the back wall 34 of the casing with other electrical equipment of the oven, is positioned centrally with respect to the width of the cooking chamber although it is offset towards the lower half of the cooking chamber. Opposite the eye of the fan 36 an inlet 42 in the rear panel opens into the fan housing a little above the level of the top of the draught break 32 over the burner chamber 31. The inlet 42 may be a single large aperture, possibly covered with a perforate guard, or it may comprise a plurality of smaller holes formed in the rear panel, as indicated in Figure 1.A cowl 43 is provided on the rear panel over the inlet 42 which extends for a substantial part of the width of the cooking chamber and further than the length of the burner chamber 3 1. The bottom of the cowl 43 projects forwards from the rear panel a distance substantially equal to the distance of the rear edge of the draught break 32 from the rear panel, and it is spaced above the draught break. Products of combustion from the burner 23 rising from the burner chamber are drawn into the fan chamber 35 through the inlet 42 by the fan, the cowl 43 ensuring that most of the products are directed into the fan chamber. The draught break reduces the effect of the draw at the inlet 42 on the performance of the burner.

In a row near the bottom of the rear panel, at either side of the upstanding housing 27, are distribution outlets 44, Figure 1, for products to leave the fan chamber 35 to be circulated in the cooking chamber. Those outlets 44 are below the level of the bottom shelf 17' which, because it is imperforate, effectively channels the products underneath it to the front of the cooking chamber. A deflector 45, Figure 2, mounted on the oven door 8 serves, when the door is closed, to direct the products upwards and over the bottom shelf at the front of the cooking chamber, and back across the chamber. Further rows of outlets 46,46' are provided near the top of the rear panel and at an intermediate level just above the cowl 43.

Inside the fan chamber 35 there are baffles 47 and 48 respectively immediately above the bottom row of outlets 44 and directly below the intermediate row of outlets 46'. These baffles 47,48 project horizontally from the back of the rear panel and help to straighten flow of the products from the fan chamber out of the outlets. Further, vertically disposed, louvre baffles 49 on the back of the rear panel are positioned between the outlets 44 in the bottom row to assist in the distribution of the products by the fan to those outlets.

Also, at the rear panel are upwardly-directed vents 50, Figure 2, which open from the lower end of the fan chamber into the burner chamber 3 1 behind and just above the level of the burner. They assist in controlling the combustion conditions in the burner chamber.

The rear panel is made up of two back-toback plates, one a liner 51 facing into the cooking chamber and the other a metering plate 52 facing into the fan chamber. The liner 51 is formed with: oversize openings at all of the outlets 44,46,46' of the rear panel; the cowl 43, whch is pierced and pressed out of the liner to leave a large aperture around the inlet 42, and the vents 50. The metering plate 52 has the outlets formed in it, the inlet 42, and apertures at the vents 50. The baffles 47 and louvre baffles 49 are provided on the metering plate and may be formed out of the plate, or they may be attached to it. Because of the composite construction of the rear panel the inlet, outlets, baffles and louvre baffles can all be precisely formed and dimensioned, and the liner can be enamelled.

Illumination of the interior of the cooking chamber is provided by a lamp, not shown, which is mounted behind the back wall 34 of the casing with the electric motor of the fan inside the aforementioned cover, and shines through glass lenses 53,54 located in the back wall and rear panel respectively.

In use of the oven with the fan operating, the products of combustion from the burner are drawn out of the burner chamber into the fan chamber, and then distributed to the cooking chamber through the outlets in the rear panel. The interior of the fan chamber becomes pressurised, typically to about 1 millibar, whilst the fan is in operation. Products which pass through the bottom outlets 44, as previously explained, flow under the bottom shelf 17 to the front of the cooking chamber before circulating up through the cooking chamber. Air is circulated with the products as well through the fan chamber and cooking chamber, and there will be re-circulation of air and products from the cooking chamber into the fan chamber and out into the cooking chamber again. Access to the inlet of the fan chamber from the cooking chamber is over the draught break 32 and under the cowl 43.

The products finally leave the cooking chamber by way of the exhaust outlet 18 in the roof panel 15.

The fan can be selectively operated, automatically if desired. When the burner is operating without the fan products can pass directly into the cooking chamber from the burner chamber through the open top of the upstanding housing whilst some products will find their way through the fan chamber and into the cooking chamber that way.

The cowl and draught break assist in shielding the burner from matter which may fall into the cooking chamber during cooking.

Claims

1. A fan-assisted gas-fired cooking oven having a cooking chamber above and towards the rear of a floor of which is a gas burner, and at or behind which cooking chamber there is a fan chamber in which a motor-driven fan is housed operative to draw products of combustion from the burner through an inlet or inlets into the fan chamber and to circulate them back into the cooking chamber from the rear of that chamber by way of one or more distribution outlets opening from the fan chamber.

2. An oven according to claim 1 in which a cowl is provided above the burner to direct the products of combustion from the burner into the inlet or inlets of the fan chamber.

3. An oven according to claim 2 in which the cowl extends across at least a substantial part of the width of the cooking chamber.

4. An oven according to any preceding claim in which a draught break is provided between the burner and the inlet or inlets of the fan chamber to reduce the effect of the fan on the performance of the burner.

5. An oven according to any preceding claim in which the burner is provided at an opening in a raised portion of the floor in front of a rear panel of the cooking chamber.

6. An oven according to any preceding claim in which the burner is provided behind a screen in the cooking chamber.

7. An oven according to claim 6 in which the screen is part of a housing provided around the burner inside the cooking chamber.

8. An oven according to claim 7 as it depends from claim 4 in which the draught brake is defined by a part of the housing.

9. An oven according to claim 7 or claim 8 in which the housing entrains at least a substantial part of the products of combustion and guides them to flow towards the inlet or inlets of the fan chamber.

10. An oven according to any preceding claim in which one or more air outlets are provided leading from the fan chamber into the cooking chamber behind the burner.

11. An oven according to claim 10 as dependent on claim 8 in which the air outlets open into the housing.

12. An oven according to claim 10 or claim 11 in which the air outlets are upwardly directed from the fan, chamber.

13. An oven according to any preceding claim in which a distribution outlet is, or-at least some of the distribution outlets are, positioned at or close to the floor at the rear of the cooking chamber.

14. An oven according to any preceding claim in which a substantially imperforate shelf is supported in the cooking chamber just above the level of the outlet, or at least some of the outlets, so that a duct is defined below the shelf which channels the products of combustion towards the front of the cooking chamber from the distribution outlet or outlets.

15. An oven according to claim 14 in which a baffle is provided at the front of the cooking chamber to direct the products of combustion back across the cooking chamber again.

16. An oven according to claim 15 in which the baffle is provided on a door of the cooking chamber.

17. An oven according to claim 15 or claim 16 in which the baffle is removably mounted.

18. An oven according to any preceding claim in which there are several distribution outlets and in which some of the outlets are at upper and/or intermediate parts of the rear of the cooking chamber.

19. An oven according to any preceding claim in which baffles are provided in the fan chamber to assist distribution of the products of combustion to the distribution outlet or out lets.

20. An oven according to claim 19 in which the baffles in the fan chamber straighten the flow of products of combustion into the cook ing chamber.

21. An oven according to any preceding claim in which an exhaust outlet for the products of combustion to pass out of the cooking chamber after they have circulated in the chamber is positioned at or near the front of the roof of the cooking chamber, and con nects with a passage extending over the cooking chamber to a flue at the back of the oven so that the products impart heat to the roof of the chamber as they pass along the passage to the flue.

22. An oven according to any preceding claim in which the or each distribution outlet leading from the fan chamber to the cooking chamber opens into the cooking chamber at the rear of the cooking chamber.

23. An oven according to any of claims 1 to 21 in which there is some distribution of products of combustion to a side or sides of the cooking chamber.

24. An oven according to any preceding claim in which the fan chamber is substantially defined between a back wall of the oven and the rear face of a transverse rear panel which extends upwardly at the rear of the cooking chamber and defines the rear wall of the cooking chamber.

25. An oven according to claim 24 in which the fan chamber extends for substantially the entire height of the cooking chamber.

26. An oven according to claim 24 or claim 25 in which the back wall and rear panel are held spaced apart by spacers provided between them.

27. An oven according to any one of claims 24 to 26 in which the rear panel is removably mounted in the oven.

28. An oven according to anyone of claims 24 to 27 in which the rear panel comprises a liner plate facing into the cooking chamber and a metering plate facing into the fan chamber in back to back relationship, the metering plate having metering apertures with which apertures in the liner plate register to form the or each inlet and distribution outlet.

29. An oven according to claim 28 in which the cowl is formed from the liner plate to leave a large cowl aperture in the liner plate with which cowl aperture smaller inlet apertures provided in the metering plate are registered so as to form the inlet to the fan chamber.

30. An oven according to claim 28 or claim 29 in which baffles provided in the fan chamber to assist distribution of the products of combustion to the distribution outlet or outlets are formed from the metering plate.

31. A fan-assisted gas-fired cooking oven substantially as described and illustrated herein with reference to the accompanying drawings.