Ventilation hood

Abstract

The present invention relates to a ventilation hood, in particular a self-cleaning ventilation hood intended for professional use and comprising filtration means (5) housed in a plenum (4), which is substantially closed in its lower part. The plenum (4) comprises at least two openings (3) on the outside of the hood, through which openings the air is drawn into the plenum (4) and through the filtration means (5), said at least two openings being located at different heights with respect to the vertical axis of the ventilation hood.

Description

[0001] The present invention relates to a ventilation hood, particularly intended for use in a professional kitchen, and more specifically a self-cleaning ventilation hood.

[0002] In a professional kitchen, a ventilation hood designed to retain grease, vapors, and fumes from a cooking range typically includes filtration devices and means for cleaning these devices while the hood is in operation. These cleaning devices are generally arranged to deliver a cleaning product diluted in water to the filtration devices.

[0003] Self-cleaning professional ventilation hoods generally include a plenum housing the filtration and cleaning components. The plenum opens on one side to the chimney through which the filtered air is exhausted, and on the other side to the exhaust air intake above the cooktop. Since the cleaning solution must not drip back onto the cooktop, the plenum's intake opening on the exhaust air intake must be large enough to draw away the exhaust air without releasing the cleaning solution. The intake opening must be sized and positioned to capture the exhaust air as efficiently as possible.

[0004] Document CN 2 324 456 describes a ventilation hood comprising filtration means housed in a plenum closed at its lower end. The plenum has two openings, one located at the top and the other at the bottom of the hood. Thus, the hood openings are located at different heights and are staggered so as not to overlap.

[0005] Document CH 692 516 describes a clay bead filter hood. Document EP 2 829 810 describes an improvement in which the clay bead hood is self-cleaning and the beads have an initially acidic pH.

[0006] Document CN 204 923 131 describes a hood whose wall includes several openings which are at different height levels and are not superimposed.

[0007] US document 2018 / 154372 describes an electrostatic precipitator for remediation of emissions in a restaurant or kitchen environment comprising a misting device to cool the airflow by evaporative cooling.

[0008] Document WO 2005 / 078353 describes a self-cleaning filtration system suitable for use in a ventilation hood, comprising two filters and two nozzles for dispersing the cleaning solution. This document specifies the arrangement of several chambers within the filtration system, separated by baffles to prevent the cleaning solution from escaping the system.

[0009] The aim of the present invention is to provide a ventilation hood, in particular a self-cleaning ventilation hood, which is efficient and compact.

[0010] The present invention relates to a ventilation hood according to claim 1.

[0011] The attached figures schematically illustrate, by way of example, one embodiment of a ventilation hood according to the invention.

[0012] There figure 1 illustrates one embodiment of a ventilation hood according to the invention.

[0013] THE figures 2 et 3 are cross-sectional views of the hood of the figure 1 . There figure 3 illustrates in particular the operation of an air cooling system before filtration fitted to the hood according to the described embodiment.

[0014] The ventilation hood according to the invention comprises a casing 1, the lower part of which is intended to be located above a cooker (not illustrated), while the upper part is intended to be connected with an exhaust chimney 10.

[0015] The enclosure 1 is closed on one side by a base 100. Hereafter, the terms "front" and "rear," and "exterior" or "interior" of the hood will be defined in relation to this base 100. The terms "vertical," "horizontal," "lower," and "upper" are defined in relation to the hood's orientation in the figures. In particular, the rear of the hood refers to the part of the hood closest to the base 100 on the horizontal axis, while the front of the hood refers to the part of the hood furthest from the base 100 on the horizontal axis. Similarly, the depth of the hood is its dimension on the horizontal axis relative to the base 100.

[0016] In its lower part, the casing 1 is partially closed by one or more panels 2. According to the invention, the panels are arranged to form at least two passages 3 or intake openings through which vapors and fumes from a cooker located under the hood are drawn. According to the invention, the passages 3 are arranged to capture the stale air at at least two different height levels relative to the cooker. Furthermore, as illustrated in the figure 2 The passages 3 are not located in the same vertical plane but in two distinct vertical planes. The passages 3 are therefore offset both vertically along the vertical axis and horizontally along the hood's horizontal axis. Thus, they are not superimposed. To achieve this, the panels 2 are neither vertical nor horizontal but form a strictly acute angle (<90° and >0°) with the vertical axis. In particular, the highest passage on the hood's vertical axis is the one furthest forward, while the lowest passage on the hood's vertical axis is the one furthest back.

[0017] Vapors and fumes can be extracted by any suitable means of extraction well known to those skilled in the art, such as an extractor fan which would be placed in the box 1 of the ventilation hood or in the exhaust chimney 10.

[0018] The passages 3 each open into a chamber or plenum 4 delimited in the box 1.

[0019] The plenum 4 includes filtration means 5 as well as means for cleaning the filtration means 6. In the illustrated embodiment, the ventilation hood further includes means for cooling the foul air 7 also housed in the plenum 4.

[0020] Preferably, the panels 2 forming the two passages are removable to allow easy access to the plenum 4 and the filtration area (5, 6, 7), which may be mandatory depending on the type of hood and / or cooker.

[0021] Preferably and as illustrated in the figures, the filtration means 5 include an expanded clay bead filter as described in document EP 2829810.

[0022] Preferably, the clay ball filter 5 comprises a mostly flat upper grid 51 and a grooved lower grid 52, thus increasing its surface area. This increases the contact area between the filter 5 and the vapors and fumes from the cooker, giving the filter 5 high efficiency. Furthermore, the clay balls also help to block any sparks that might be drawn in (from charcoal or wood-burning grills).

[0023] The clay beads in the filter have a sufficiently large diameter to reduce pressure drop as grease-laden air passes through the filter. Preferably, the diameter of the beads is between 15 and 20 mm. By reducing pressure drop, the energy required to extract the fumes is also reduced. Furthermore, the larger the diameter of the beads, the easier they are to clean. The thickness of the bead bed within the frame also helps control pressure drop and filter efficiency. Indeed, the greater the thickness, the more effective the grease removal. In addition, the clay beads preferably have an acidic pH, between 5 and 5.5. This pH can be achieved by any appropriate treatment of the beads, particularly by buffering (soaking the beads in an acidic solution to lower their natural pH).With this feature, at the end of filter 5's life, after repeated washing cycles using a basic cleaning product with a pH generally between 9 and 9.5, the beads have a pH between 6 and 6.5. The initial acidity of the beads neutralizes the alkalinity of the cleaning product. This facilitates reprocessing and recycling of the beads.

[0024] The cleaning means 6 for the ball filter 5, which allow a cleaning solution (e.g., a water-cleaning product mixture) to be brought onto said filter 5, may have any suitable shape, including that described in detail in document EP 2829810. In the illustrated embodiment, the cleaning means include at least one nozzle designated by reference numeral 6.

[0025] In this embodiment, the passages 3 are further arranged so that the cleaning solution cannot flow out of the plenum 4 through said passages 3 during the cleaning of the filtration means. In particular, the passages 3 therefore form openings that are neither directed downwards towards the cooker nor vertically, but directed upwards towards the hood so that the cleaning solution cannot pass through said passages 3 and exit the plenum 4. Thus, preferably, the panels 2 form a strictly acute angle (<90° and >0°) with the vertical axis and are open or directed upwards towards the hood.

[0026] The ventilation hood, according to the illustrated embodiment, further includes means 7 for cooling the exhaust air. These cooling means 7 are housed in the plenum 4 and are designed to cool the exhaust air drawn in through the passages 3 as this airflow passes through the filtration means 5. The cooling means 7 also extinguish any sparks that may have been drawn in. This feature is particularly useful for a ventilation hood intended for cooking appliances that generate significant heat and / or flames and / or sparks, such as wood-burning or charcoal grills.

[0027] The cooling means 7 are arranged to disperse cold water onto the filtration means 5. Preferably, the cooling means 7 are arranged to mist the water onto the filtration means 5, that is, to vaporize water in the form of very fine droplets. The cooling means 7 can have any suitable shape, such as a nozzle as illustrated in the figures, connected to water distribution means (pump, reservoir, control means, pipe, etc.).

[0028] The cooling means 7 are further arranged to operate in the following manner.

[0029] During operation, the ventilation hood draws hot, stale air (vapors and fumes) from the cooker into the plenum 4 via the passages 3. The hot, stale air then passes through the filtration means 5, heating them. Upon command (manual or automatic), the cooling means 7 intermittently disperse or mist cold water 8 onto the filtration means 5. The cold water, preferably in the form of a mist, is drawn into the filtration means 5 by the hood and its extraction system. The filtration means 5 are thus moistened, and as the hot, stale air passes through them, any sparks are cooled and extinguished by evaporation upon contact with the water within the filtration means 5.

[0030] There figure 2 This illustrates a related effect that also partially contributes to cooling the stale air drawn in by the hood. The cold water misted by the cooling means 7 onto the filtration means will partially evaporate upon contact with the hot filtration means 5 and create a mist or fog 9. This mist 7 will spread into the plenum 4 below the filtration means 5. The figure 2 The illustration, in different shades of grey, shows the jet of cold water 8 dispersed by the cooling devices 7, as well as the mist 9 that subsequently forms. The hot, stale air passing through the mist 9 is therefore already partially cooled before being drawn through the humidified filtration devices 5.

[0031] The cooling methods 7 described above can operate intermittently, as it is sufficient to keep the filtration media 5 moist, without requiring a continuous water jet. The water consumption needed to cool fumes and vapors when using the ventilation hood is therefore reduced, even further if the water is misted, as misting results in low consumption. The cooling of the stale air is thus improved compared to known systems in which the stale air must pass through a cold water curtain to be cooled, a curtain that must operate continuously with a high water flow rate.

[0032] Preferably, the cleaning means 6, the cooling means 7 and the passages 3 are arranged so that there is no splashing on the cooker when the cleaning means and / or the cooling means are activated, i.e. that the cleaning or cooling solution cannot flow through the passages 3 out of the plenum onto the cooker.

[0033] Preferably, the 3 passages are as large as possible. Even more ideally, each of the 3 passages extends essentially along the entire length of the hood continuously.

[0034] The above-described embodiment of the ventilation hood is provided as an example only. Variations are, of course, possible. In particular, as already mentioned, the filtration means, the means for cleaning the filtration means, and / or the cooling means could have any suitable form and are not limited to those illustrated and described above. Furthermore, the ventilation hood may include any suitable control means arranged to manually or automatically control the extraction means, the means for cleaning the filtration means, and / or the cooling means.

[0035] Furthermore, the cooling means could be arranged to be part of the cleaning means and participate in cleaning the filtration means. In the embodiment illustrated, for example, the nozzle 7 is also arranged to disperse a cleaning solution onto the filtration means 5 during a cleaning cycle.

[0036] Alternatively, the cooling means could include a substrate through which the stale air can pass, placed in the plenum upstream of the filtration means. In this variant, the cooling means are arranged to intermittently disperse water onto the substrate to humidify it. The hot stale air is cooled as it passes through the substrate, and the cooled air is then drawn through the filtration means.

[0037] The ventilation hood according to the invention is characterized by the fact that it comprises filtration means housed in a essentially closed plenum and including at least two openings on the outside of the hood through which air (fumes and vapors) is drawn into the plenum and through the filtration means. These at least two openings are located at different heights relative to the vertical axis of the hood and at different depths relative to the horizontal axis of the hood. There is therefore at least one opening in an upper part of the hood and one opening in a lower part of the hood, as well as at least one opening at the front of the hood and one opening at the rear of the hood. Thus, the hood according to the invention is more efficient because it allows fumes to be captured simultaneously in the upper and lower parts of the hood, at the front and the rear.The fumes are more likely to be drawn through one or the other of the openings to the filtration system. With at least two openings, there is also a larger suction area, resulting in a reduced velocity as the stale air enters the plenum and then circulates towards the filtration system. This reduced velocity leads to reduced turbulence and therefore lower pressure losses. This reduces the energy required to extract the stale air. Furthermore, the suction area is increased without increasing the size of the hood, which can even be reduced in depth compared to a prior art hood with a single suction opening and identical aerodynamic characteristics.

[0038] The ventilation hood includes means for cleaning the filtration elements, and the plenum is closed at its lower end so that the cleaning solution passing through the filtration elements cannot flow through the bottom of the plenum onto the cooker. The cleaning solution is preferably collected at the bottom of the plenum before being disposed of (wastewater or a reprocessing tank).

[0039] Preferably, the filtration means include at least one expanded clay bead filter.

[0040] The ventilation hood further includes means for cooling the air drawn in through the openings in the plenum. Said cooling means are arranged to intermittently disperse cold water onto the filtration means or onto a substrate that the air can pass through and is placed upstream of the filtration means, so that the water drawn in by the hood through the substrate or the filtration means moistens said substrate or said filtration means, and so that the air drawn in through the openings in the plenum is cooled by evaporation of the water, any sparks being extinguished, as it passes through said moistened substrate or filtration means.

Claims

1. Ventilation hood comprising filtration means (5) housed in a plenum (4) of the hood, said plenum being substantially closed in its lower part, the plenum (4) comprising at least two openings (3) to the exterior of the hood through which the air is drawn into the plenum (4) and through the filtration means (5), said at least two openings being located at different height levels with respect to the vertical axis of the ventilation hood, said at least two openings being located in distinct vertical places so as not to be superimposed, the hood further comprising means (6) for cleaning the filtration means (5), the plenum (4) being closed in its lower part such that a cleaning solution dispersed by the cleaning means and passing through the filtration means (5) cannot flow through the bottom of the plenum to the exterior of the ventilation hood, characterised in that it further comprises means (7) for cooling the air drawn in through the openings (3) into the plenum (4), said cooling means (7) being arranged to disperse, intermittently, cold water (8) onto the filtration means (5) or onto an air-permeable substrate placed upstream of the filtration means (5) such that the water drawn in by the hood through the substrate or the filtration means (5) humidifies said substrate or said filtration means (5) and such that the air drawn in by the openings (3) into the plenum (4) is cooled by evaporation of the water when it passes through said humidified substrate or filtration means (5); and in that the openings (3) are arranged such that the cleaning solution cannot flow out of the plenum (4) through said openings (3).

2. Ventilation hood as claimed in the preceding claim, characterised in that the openings (3) are formed in a wall of the plenum (4) arranged such that said wall forms a strictly acute angle, i.e. strictly greater than 0° and strictly less than 90°, with the vertical axis of the hood.

3. Ventilation hood as claimed in the preceding claim, characterised in that the wall of the plenum is formed as a single piece or is formed of several elements.

4. Ventilation hood as claimed in any one of the preceding claims, characterised in that the openings (3) are obtained by the arrangement of at least two panels (2) forming walls of the plenum (4), said panels being removable so as to allow access to the plenum (4) and to the filtration means (5).

5. Ventilation hood as claimed in any one of the preceding claims, characterised in that the openings (3) are substantially directed towards the top of the hood.

6. Ventilation hood as claimed in the preceding claim, characterised in that the openings (3) are formed in a wall of the plenum (4) arranged such that said wall forms a strictly acute angle, i.e. strictly greater than 0° and strictly less than 90°, with the vertical axis of the hood, said angle being directed or open upwards in relation to the vertical axis of the hood.

7. Ventilation hood as claimed in any one of the preceding claims, characterised in that the filtration means (5) comprise at least one expanded clay ball filter.

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