EP0753706B1 - Smoke exhaust system, in particular exhaust hood - Google Patents

Abstract

The fume extraction system generates a continuous air curtain (F) along a truncated surface surrounding the extraction zone. The air is rotated and diverges as it descends along the surface. The induced fumes rise along a vortex column (F') located in the middle of the zone. The system comprise an upper dome (1) whose top (10) is located on the column axis (XX'). A lower dome (2), with the same axis, has its top displaced along the axis relative to the upper dome and has an opening (20) centred on the axis. A ventilation system (4) is placed on the axis between the tops of the upper and lower domes. The ventilation system comprises turbines for generating radial air in the air guide (3), delimited by the domes, and axial air induction in the zone through the opening. The upper and lower domes are directed downwards and widened so that the air speed vector leaving the guide has a vertical component and two horizontal components. There is a fume filtering system (5,6).

Description

The present invention relates to a suction system for fumes produced in a specific area.

The field of application concerned more particularly, although not exclusively, by the invention is that of the extractor hoods used above cooking appliances to filter odors and particles greasy from cooking food.

So that the suction of the fumes produced in the area of the cooking space is efficient, it seems desirable to isolate the cooking area from the outside.

It is already known to separate two given zones by a curtain flat air, namely a light curtain which prevents the passage of small particles such as dust, fine droplets, vapors or fumes.

It is known in particular in the Siemens patent FR-A-1535989 a exhaust system for fumes produced in a specific area comprising means for generating two continuous air curtains descending in divergence on either side of said area and means aspiration of the fumes.

The present invention proposes to generate a new type of air curtain which improves the suction phenomenon.

More specifically, the present invention relates to a system suction of fumes produced in a specific area, comprising means for generating a continuous curtain of air surrounding said zone according to an immaterial surface and a ventilation system characterized in that said means comprise an upper dome whose apex is located substantially on the axis of the column, a dome lower of the same axis whose vertex is offset along said axis by report at the top of the upper dome and has an opening substantially centered on said axis, and a ventilation system placed on the axis between the vertices of the upper and lower domes, said system ventilation comprising means for radially generating air in the air guide defined by the domes and axial air suction means included in the area, through the opening, the upper domes and being further downward and flared so that the vector speed of the air leaving the guide has a vertical component and two horizontal components.

In a preferred variant of the invention, the suction system further comprises a device for filtering the aspirated fumes.
The present invention also relates to an extractor hood for a cooking appliance comprising a suction system as defined above, in which the filtration device uses a filter for cooking odors and a filter for grease emanating from the cooking.

In the single appended figure, there is shown schematically a partial sectional view of possible constituent means of a system according to the invention.

The actual generation of the air curtain and descending along a frustoconical intangible surface according to the invention can be obtained very simply, by the use of two cupolas 1, 2 of same axis XX 'forming an air guide 3, and a ventilation system 4 placed in the air guide.

More specifically, the upper dome 1 has a vertex 10 placed on the axis XX 'and is oriented downwards and flared as shown the figure. The lower dome 2 has its apex on the axis XX ', and has also a flared shape down. The ventilation system 4 is placed on the axis XX 'between the two vertices, and includes means generating air radially in the air guide. The shapes of the two domes are such that the air flow leaving the air guide has a velocity vector with vertical and horizontal components, so that the air curtain can rotate down and diverge along a trunk cone, as shown schematically by the arrows F. More precisely, due to the frustoconical shape of the air curtain, the vector speed has a vertical component and two components horizontal.

At the air guide outlet, the walls of the domes must be tilted relative to the vertical to allow the vector speed of performing an angle α with the vertical, preferably between 10 and 45 degrees. The domes for example have the shape of caps spherical.

We can consider having domes forming an air guide 3 to constant section. However, preferably, the shapes of the domes will be chosen so as to delimit a section air guide converging towards the exit of the guide. Thus, the air contained in the guide is pressurized and exits at a higher speed, which gives the spinning air curtain better stability.

A grid 7 may be provided at the outlet of the air guide for the laminarization of the output flow, which limits turbulence.

In all cases, and in accordance with the present invention, the air included in the area bounded by the air curtain goes, due to the movement whirling and descending the air curtain, being trained in turn by rotation, by friction.

In addition, the ventilation system 4 vertically draws in the air located in said zone, through an opening 20 made at the top of the lower dome 2 and substantially centered on the axis XX '.

The two movements (rotation and upward translation) will combine to create an ascending type immaterial column vortex, symbolized by the arrow F '. So all the particles (odors, grease, dust, ...) present in the area delimited by the air curtain will be sucked through opening 20.

The ventilation system 4 can be constituted by any turbine with axial suction and radial air generation, for example by a turbine reaction or by a squirrel cage type turbine.

For application in the cooking sector, the previous ventilation can be supplemented by a filtration system fumes that have been sucked out.

As illustrated in the figure, this system can be composed of a filter for filtering odors, such as an activated carbon filter 5, and / or a filter to retain grease, such as an expanded metal filter 6.

A complete range hood for cooking appliance can be obtained by dressing the previous suction system with a bodywork (not shown), which will advantageously carry the suction system controls and any lighting.

The advantages provided by the present invention are in particular The following :

By artificially recreating a vortex phenomenon by the combination of upward suction and rotational movement obtained by the swirling air curtain, the suction is significantly improved fumes.

Furthermore, such a vortex phenomenon can be obtained with a system with a small footprint: typically, for a hood the top of the domes can be spaced a distance apart less than ten centimeters.

In addition, due to the creation of a closed air curtain, based curvilinear, the suction system is applicable to cooker hoods intended to be against a wall, but also in the center of a room, in a configuration said in island.

Finally, although the figure illustrates a system in which all the air sucked into the riser is recycled into the air guide it's all quite conceivable to apply the same principle to an extractor hood. In this case, two motors are preferably used, one for the generation of the air curtain, the other by suction.

Claims (9)

1. System for extracting vapours produced in a given zone, having means making it possible to generate a continuous curtain of air (F) surrounding said zone along an immaterial surface, and a ventilation system, characterised in that said means have an upper cupola (1) the highest point (10) of which is situated substantially on the axis (XX') of the column, a lower cupola (2) having the same axis and the highest point of which is offset along said axis with respect to the highest point of the upper cupola and presents an opening (20) substantially centred on said axis, and a ventilation system (4) positioned on the axis between the highest points of the upper and lower cupolas, said ventilation system having means for generating air radially in the air guide (3) delimited by the cupolas and means for axially extracting the air comprised in the zone, through the opening, the upper and lower cupolas being furthermore downwardly orientated and flared in such a way that the speed vector of the air on the output side of the guide possesses a vertical component and two horizontal components.
2. Extraction system according to claim 1, characterised in that said speed vector on the output side of the air guide is inclined by an angle of between 10 and 45 degrees with respect to the vertical.
3. Extraction system according to either of claims 1 and 2, characterised in that the upper and lower cupolas delimit an air guide of constant section.
4. Extraction system according to either of claims 1 and 2, characterised in that the upper and lower cupolas delimit an air guide whose walls converge towards the outlet from the guide.
5. Extraction system according to any of claims 1 to 4, characterised in that the cupolas have the shape of a spherical dome.
6. Extraction system according to any of claims 1 to 5, characterised in that the ventilation system is a reaction turbine.
7. Extraction system according to any of claims 1 to 5, characterised in that the ventilation system is a turbine of the cage winding type.
8. Extraction system according to any of the preceding claims, characterised in that it furthermore has a device (5, 6) for filtering the extracted vapours.
9. Extraction hood for a cooking range, having an extraction system according to claim 8, characterised in that the filtering device has a filter (5) for filtering the cooking smells and a filter (6) for the greases produced in the cooking process.

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