WO2013186133A1

WO2013186133A1 - Filter arrangement for a vapour extraction hood

Info

Publication number: WO2013186133A1
Application number: PCT/EP2013/061778
Authority: WO
Inventors: Egon Feisthammel; Steffen Moser; Udo Reiff
Original assignee: BSH Bosch und Siemens Hausgeräte GmbH
Priority date: 2012-06-14
Filing date: 2013-06-07
Publication date: 2013-12-19
Also published as: EP2861910A1; DE102012210000A1

Abstract

The invention relates to a filter element (10) for a household vapour extraction hood, with a filter frame (12), a first filter stage (18) and a second filter stage (32) arranged between the first filter stage (18) and an upper, clean-air side (14) of the filter frame, wherein the first filter stage (18) is constructed in the form of an eddy current filter and the second filter stage (32) is in the form of a stretched metal filter, and the two stages are jointly received in the filter frame (12).

Description

Filter arrangement for an extractor hood

The invention relates to a filter element for a household extractor hood with a filter frame, a first filter stage and a second filter stage.

When aspirating and cleaning of fumes, which are produced during cooking, filter assemblies are generally used in household extractor hoods, in which multiple layers of an expanded metal are used as filter material. Through the openings in the individual expanded metal layers and the resulting change in direction of the fumes and vapors, particles, in particular fat and liquid particles from the vapors and fumes are filtered out and are deposited on the expanded metal layers. Such filter materials are usually sufficient to accommodate the accumulating in households filter quantities.

However, in households predominantly cooking processes are used in which a larger amount of fat, especially low-viscosity fat, is obtained and also a large amount of water vapor is formed, such as in the preparation in a wok, such filter assemblies are usually not sufficient. Due to a limited

Storage capacity of the individual expanded metal layers is especially when switching off the hood the risk that the detected fat in the filter and

Liquid particles accumulate in the lower part of the filter. It can be so

Dripping and dripping of the oil come out of the filter.

If such large quantities of oils and fats have to be diverted, you can

Eddy current filters are used. These filters usually comprise a first and a second series of half-shells which are spaced apart, directed against each other and laterally offset from one another. The half-shell rows have openings through which an exhaust steam loaded with grease and liquid particles

Can flow through arrangement. Due to the lateral offset of the half shells form eddy currents between the two rows, in which the heavy fat and Centrifuge liquid particles outwards to the walls of the half-shells and settle there.

However, for reasons of stability, higher eddy current filters must be used

Material strengths are used, whereby the component weight and the part price rise. In addition, conventional eddy current filter design due to increased space requirements. A use of an eddy current filter in the household is also opposed to a narrow range of flow rate, in which the

Eddy current filter can achieve an optimal grease removal rate. To achieve this high flow rate high-performance blowers are installed with a correspondingly high blower capacity, with which usually a high

Noise is associated. Such eddy current filters are therefore not suitable for use in households. The invention has for its object to provide a filter element for a cooker hood, with an optimized deposition rate of fat and liquid particles in the household area even at a high pollution load of fumes by fats and liquid particles, as is customary in Asian cuisine, can be achieved , This object is achieved in a filter element of the type mentioned above in that the first filter stage is formed in the form of an eddy current filter, the second filter stage in the form of an expanded metal filter and disposed between the first filter stage and a clean air side top of the filter frame and the two filter stages together the filter frame are added.

The particles and / or liquid drops which are deposited in the filter element are also referred to below as impurities. The one with these

Impurities laden airflow is also referred to as vapor or vapor. As a filter element according to the invention is preferably understood a filter cartridge. The filter element preferably represents a grease filter of a household extractor hood. According to the invention, the clean air side designates the side of the filter element in the region of the filter stages, via which the purified air exits the filter element during operation of the household extractor hood and thus lies opposite the upstream side. The clean air side of the filter element is hereinafter also referred to as the top of the filter element designated. As the clean air side top of other components of the filter element, the side of the component is referred to, which faces the clean air side of the filter element, that is directed upwards. Accordingly, the suction side of the filter element is referred to as the bottom of the filter element and the sides of the components which are directed towards the suction side or lie in this as

Called subpages. The household extractor hood is also referred to below as an extractor hood. As a filter stage of the filter element, which is also referred to below as a stage, the components of the filter element are referred to, which act together for a type of filtering. Filtration, also referred to as filtering, refers to the purification of the laden air from at least part of the impurities contained therein. The filter frame is in

The following also simply referred to as a frame. As held in the filter frame filter stages is called a filter stage in which at least a part of the edge of the filter stage forming these components is accommodated in the filter frame. As an arrangement between the first filter stage and the clean air side of the filter element of the second filter stage, an arrangement of the second filter stage is referred to, in which the components of the second filter stage preferably not over the top of

Frame up, that is, the top of the second filter stage with the top of the filter frame is flush.

The combination of the two filter stages according to the invention are two

various mechanisms of action, which can also be referred to as filter mechanisms, united in a filter element. In this case, in the first filter stage, the filtration according to the principle of an eddy current filter, whereby a high deposition rate of fat and liquid particles can be made from the air flow. This prefiltered air stream subsequently flows through the second filter stage, in which a second, final filtration takes place according to the operating principle of an expanded metal filter, essentially independent of the flow velocity of the air stream. With the invention

Filter element can thus be filtered over a wide range of flow rates even with a high pollution load laden air flow without significant loss of filtration efficiency.

By the two filter stages are included in a single frame, also these two filter stages can be introduced together in the hood and be taken from this. In addition, since the second filter stage is disposed between the first filter stage and the clean air side upper side of the frame and thus does not protrude upwardly beyond the frame, the filter element of the invention may be housed in a fume hood instead of a conventional expanded metal filter cassette

be recorded. This does not require any modification of the extractor hood.

Preferably, the first filter stage of an upstream outer panel, the

In some areas inlet nozzles, each having a raised edge, and a plate parallel to the outer plate arranged baffle plate having offset to the inlet nozzles slots formed. In this embodiment too, a first type of filtration is thus carried out in the first filter stage and a second type of filtration in the second filter stage. The upstream side outer plate is also referred to simply as the outer plate below.

For horizontal installation of the filter element in the hood is the

upstream outer plate directed downward, facing the rising vapors, and the raised edge of the inlet nozzles facing the underside of the outer plate vertically upwards. The passing through the inlet air flow is directed by the raised edge in the direction of the baffle plate, ie

fluidically optimized directed to the baffle plate, where the impurities of the air stream are partially deposited in a first filtration. In this case, a large part of the impurities can be deposited already in the first filter stage. Since the baffle plate is just formed, the space requirement of the first filter stage is low. Thus, the height of the entire filter element and thus the space required for installation of the filter element in the hood can be minimized and yet the principle of the eddy current filter and the principle of an expanded metal filter can be combined.

Through the slits provided in the baffle plate, the now prefiltered air stream flows and into the second filter stage in which a second filtration takes place. The baffle plate can also be formed as a perforated plate. The slots in the baffle plate and the inlet nozzles of the outer plate, in particular the openings of the inlet nozzles, are designed, that is, in particular have a size such that thereby fluids, in particular in the form of impurities, can pass in the air. The slots and

Inlet nozzles are therefore also referred to as fluid. The inlet nozzles are Preferably designed as elongated nozzles, that is, extend in the

Longitudinal direction or the width direction of the outer plate. Particularly preferably, the slots and the inlet nozzles have the same length. As staggered slots and inlet nozzles is preferably referred to an arrangement in which the air emerging from the inlet nozzles in the main flow direction of the air impinges on areas of the baffle plate in which no slots are provided. In addition, the slots and inlet nozzles are preferably aligned parallel to each other. By such an offset and preferably parallel alignment of the slots and inlet nozzles, an unpurified passage of the air is prevented by the first filter stage and achieved the required for the purification of the air turbulence of the air.

The first filter stage of the filter element is preferably at least partially over a lower edge of the filter frame in the direction of flow, ie in the direction of the vapor source over. Since the installation space for a filter element in extractor hoods is generally limited upwards, no collision problem arises in this embodiment between the first filter stage and the installation space provided for a conventional expanded metal filter. The filter element is therefore compactly constructed and can be integrated into a conventional frame in a suction opening of a fume hood, whereby attachment to conventional fastening systems is possible.

The outer plate is preferably formed as a deep-drawn part. An outer panel produced in this way has the advantage that the production is simple and yet the required geometry, in particular the inlet nozzles can be reliably produced. As the material for the outer plate is preferably anodized aluminum or thin stainless steel is used, whereby the weight of the outer plate is kept low and the filter element is lightweight as a whole.

Most preferably, the outer plate and the baffle plate are joined together to form a composite part. The joining is preferably carried out via Druckfügetechnik. This offers the advantage that only small areas are required for setting the joining points. As a result, joining points are provided centrally on the outer and impact plate, resulting in a high rigidity of the first filter stage. The impact and the outer plate can thus be provided with a low material thickness, without affecting the stability of the composite part is adversely affected. This results in a Low-weight design of the first filter stage. Furthermore, the formation of the filter is simplified by the formation of the first filter stage as a composite part, since the first filter stage is present as a single component in the manufacture of the filter element and in particular alignment of the slots and inlet nozzles in the final assembly of the filter element is no longer required.

Between the raised edges of the inlet nozzles, a fluid-holding collecting volume is preferably formed for fluid dripping out of the vapor from the first and the second filter stage. Thus, a dripping of deposited impurities from the filter element is prevented. This is hygienic and also eliminates the risk of fire by igniting the drops. In addition, by providing the collection volume through the outer panel itself, it is not necessary to provide a separate collection container. The second filter stage preferably comprises an outer layer arranged on the clean air side and a corrugated inner layer adjoining the baffle plate, wherein the corrugations of the inner layer are arranged perpendicular to the alignment of the slots in the baffle plate and to align the inlet nozzles. In this case, the outer layer and the inner layer each comprise at least one layer of expanded metal. Due to the waveform of the inner layer, the filter surface is advantageously increased, whereby the filter performance and the retention capacity of the inner layer rise.

The baffle plate may be formed with embossments for maintaining a distance between the slots and the second filter stage. This increases the retention capacity of the expanded metal, since it avoids that held in the expanded metal liquid

Impurities can drain without droplet formation from the second to the first filter stage. In addition, stampings in the baffle plate can increase the stability of the baffle plate and thus the first filter stage and the requirements for the material thickness are therefore further reduced.

In one embodiment, the filter frame forms part of the outer panel. In this embodiment, for example, the edge of the outer panel may be bent upwardly at the edges and the ends of the upturned edges may then be bent inwardly again. This allows the outermost edge of Outer plate rest on the top of the second filter stage and so press on the top of the first filter stage or at least hold in position. The advantage of this embodiment is in particular in the simplified production, since a separate frame does not have to be provided and so the number of parts can be reduced. According to one embodiment, the filter frame is formed by deep drawing or bending on the outer plate. Other manufacturing methods, such as edges, can be used to form the filter frame.

The invention will be described again below with reference to the accompanying figures. Show it:

Figure 1: a schematic sectional view of an embodiment of a

filter element according to the invention;

FIG. 2 is a schematic exploded view of the embodiment of FIG

filter element according to the invention of Figure 1;

Figures 3a and 3b: a schematic sectional view of the first filter stage, as it is joined together by means of a joining tool to form a composite part and a schematic plan view of the provided with joining points

Flapper.

FIGS. 1 and 2 show an embodiment of a filter element 10 according to the invention. The filter element 10 has a filter frame 12, a first filter stage 18 and a second filter stage 32 arranged between the first filter stage 18 and a clean air-side upper side 14 of the filter frame 12.

The first filter stage 18 has an upstream outer plate 20 with partially inlet nozzles 22, each with a raised edge 24. Between the raised edges 24, a collecting volume 26 for dripping impurities P is formed. The inflow nozzles 22 each have a longitudinal extension and are provided parallel to one another in the outer panel 20. The outer plate 20 may be formed in the illustrated embodiment as a deep-drawn part of aluminum or stainless steel with a low material thickness, about 0.5 mm. Furthermore, the first filter stage 18, in particular the outer panel 20, at least partially over a lower edge 16 of the Filter frame 12 in the direction of flow over. When mounted horizontally of the filter element, the inflow side is in the direction of the vapor source, ie directed downwards.

Parallel to the outer plate 20, that is to the areas of the outer plate 20, which lie between the inlet nozzles 22, a baffle plate 28 is arranged, which to the

Inflow nozzles 22 offset slots 30 has. The baffle plate 28 is configured flat in the illustrated embodiment.

In addition, FIG. 1 shows an air flow W, which is also referred to as vapor, which entrains impurities P in the form of fat and liquid particles, which are filtered out by the filter element 10 according to the invention.

The air stream W loaded with the impurities P flows through the inlet nozzles 22 into the first filter stage 18 of the filter element 10. The inlet nozzles 22 direct the air flow W directly onto the baffle plate 28. The impingement of the baffle plate 28 causes first impurities to settle on the baffle plate 28 then go into that

Drainage volume 26 can drain. In addition, the impingement of the air flow W deflects it in its direction, so that eddy currents occur in the first filter stage 10. In these eddy currents, the heavy fat and liquid particles migrate centrifugally outward and can be at the baffle plate 28 or on the

knock down raised edges 24 and finally drip into the collection volume 26.

Even in this first filtration step in the first filter stage 18, a large part of the entrained with the air flow W impurities P can be deposited and collected.

From the first filter stage 18, the air flow W finally flows through the laterally offset to the inlet nozzles 22 slots 30 of the baffle plate 28 in the second filter stage 32nd

The second filter stage 32 has a clean air side, that is, the inflow side

opposite, arranged outer layer 34 and an adjacent to the baffle plate, corrugated inner layer 36 (see Figure 2). The corrugations of the inner layer 36 extend perpendicular to the longitudinal extension of the slots 30. By the corrugated arrangement of Inner layer 36, which increases the overall filter surface of the inner layer 36, and their orientation perpendicular to the orientation of the slots 30 in the baffle plate 28 and the orientation of the inlet nozzles 22, the filter efficiency of the second filter stage 32 is significantly increased.

The outer and the inner layer are formed from at least one layer of expanded metal. Through the openings in the individual expanded metal layers and thereby

caused directional change of the air flow W, the impurities P, in particular fat and liquid particles are filtered out of the air flow W and accumulate on the expanded metal layers. Should the storage capacity of the

Exceeded expanded metal layers, any dripping impurities can also be included in the collection volume 26.

FIG. 3 a shows, like the outer plate 20 and the baffle plate 28, at its edge regions by means of a tool N in the pressure-joining technique to form a composite part

be joined together. It can be seen that the space required for setting a joining point 38 is small, for example about 3 mm diameter per joining point. Thus, even in the central region of the composite part joint points 38 can be readily set (see Figure 3b), whereby the stiffness of the composite part increases. Furthermore, no reworking is necessary in this method, which reduces the manufacturing costs.

As a result of the central joining, the outer plate 20 and the baffle plate 28 may be formed with a small material thickness without having a detrimental effect on the rigidity of the filter element 10. The entire filter element 10 is therefore produced in lightweight construction, whereby additional fall protection during its attachment are superfluous. Due to the compact design according to the invention, the filter element can also be mounted with conventional filter frame.

In the following, the invention will be described again generally, partly with reference to the figures. Here, the filter element 10 is also referred to as a filter concept. The outer plate 20 may be referred to as a front cover layer, deep-drawn part, deep-drawing region or nozzle plate. The inflow side of the filter element 10 is also referred to below as the device outside. The raised edge 24 corresponds to the raised edge. The collecting volume 26 corresponds to the collecting space. The

Inlet nozzles 22 are also referred to as nozzle openings.

The filter concept according to the invention has a number of advantages. In particular, a good grease removal rate can be achieved over a wide range of flow velocity. Oils and fats can be stored or derived well. Despite the combination of an eddy current filter and an expanded metal filter, the filter element has a low part weight. Finally, due to the required at least in the edge region of the filter element small installation space, which corresponds to that of conventional expanded metal filters, a simple replacement of conventional expanded metal filter can be made without that changes to the hood would be required.

The filter element according to the invention is based on a conventional expanded metal filter and, at least in the edge region, that is to say in the region of the frame, has a standard frame height of 8-10 mm. The concept can be analogously applied to larger frame heights or to frameless perforated plate filters, that is, the filter element according to the invention can be configured with larger frame heights or as a frameless perforated plate filter, in which the first filter stage is connected upstream of the perforated plate in the flow direction.

The front cover layer, that is to say outer panel, of the filter preferably consists of a deep-drawn part (preferably of anodized aluminum, optionally of thin stainless steel) with a small wall thickness, for example 0.5 mm. In addition to the low use of materials, the fact that simpler - that is less stable - tools and presses with low press force can be used for production, advantageous.

The deep-drawn part builds up to the device outside, that is, down over the frame of the filter element over, so that no collision problem arises in the space provided for a conventional expanded metal filter installation space.

In the deep drawing area of the filter element, in particular on the outer plate

Inlet nozzles arranged. The primary function of the inlet nozzles is to conduct air optimally aerated into the filter element. By the combination of Deep-drawn part and raised edge of the inlet nozzle also creates a dense collecting space, which makes it possible to store the oils and fats deposited in the filter.

In contrast to a second row of nozzles in conventional baffle filters, a baffle plate is preferably used in the filter element according to the invention. The baffle plate is provided with slots, which allow passage of the air. The slots are offset compared to the nozzle openings. In order to achieve a higher strength and rigidity of the filter element, the nozzle plate and baffle plate may be joined together (preferably via pressure-bonding technique). This can be done on the edge of the element as well as pot impressions in the central region of the filter element. This creates a stable composite part.

The pressure-joining technique has the advantage that only small installation spaces are needed to set a joining point (for example with a diameter of 3 mm),

Different materials or material thicknesses can be connected to each other and no reworking of the surface is required. A central arrangement of individual joint points is required for reasons of rigidity.

Preferably expanded metal layers are placed on the baffle plate. For better distribution of the air in the filter and to reduce the flow resistance, the expanded metal layers should be wavy executed. The direction of the shaft should be perpendicular to the alignment of the slots in the baffle plate or to align the

Inlet nozzles can be arranged. The entire package, that is, the first and second filter stage is preferably edged and bolted in a conventional filter frame. Alternatively, a kind of filter housing can be bent out of the deep-drawn part.

The contaminated air flows through the inlet nozzles into the grease filter. The fat particles hit the baffle plate, a part of it is deposited and drips down into the trough-like deep-drawn part.

The turbulence on the inside of the inlet nozzle leads to a further separation of fat particles. The air then flows through the slots in the Impact plate in the range of expanded metal layers. There, too, oil and fat components are separated. If the oil tends to drip, it flows through the slits in the baffle plate and also drips into the tub-like deep-drawn part.

The combination of the two functional principles of the eddy current filter and the expanded metal filter creates a filter element which combines the advantages of both systems. In particular, the deposition rate of the eddy current filter can be used in the sense of prefiltering. The storage capacity and drip resistance of the

Eddy current filters can be used. In addition, the filter element can be used in a relatively large range of the flow speed of the hood without performance losses. Finally, with the filter element a high

Grease removal rate can be achieved.

Due to the integration of all elements in a conventional filter frame as well as the adoption of the fastening systems, the element is against all used

Platform components, such as conventional expanded metal filter cartridges, interchangeable. The low weight of the components also requires no additional fall protection.

LIST OF REFERENCE NUMBERS

Filter element 10

Filter frame 12

Top, filter frame 14

Bottom edge, filter frame 16

First filter stage 18

Outer plate 20

Inlet nozzle 22

raised edge 24

Collection volume 26

Baffle plate 28

Slot, baffle plate 30

Second filter stage 32

Outer layer 34

Inner layer 36

Joining point 38

Air flow W

Impurities P

Tool N

Claims

1. filter element (10) for a household extractor hood with a filter frame (12), a first filter stage (18) and a second filter stage (32), characterized in that the first filter stage (18) in the form of an eddy current filter and the second filter stage (32) is formed in the form of an expanded metal filter and between the first filter stage (18) and a clean air side top (14) of the filter frame is arranged and that the two filter stages (18, 32) are held together in the filter frame (12).

2. Filter element according to claim 1, characterized in that the first filter stage (18) from an upstream outer plate (20), the partially inlet nozzles (22) each having a raised edge (24), and a parallel to the outer plate (20) arranged baffle plate (28) having the inlet nozzles (22) offset slots (30) is formed.

3. Filter element according to one of claims 1 or 2, characterized in that the first filter stage (18) projects at least partially over a lower edge (16) of the filter frame (12) in the direction of flow.

4. Filter element according to one of claims 1 to 3, characterized in that the outer plate (20) is formed as a deep-drawn part and the baffle plate (30) is configured just.

5. Filter element according to one of claims 1 to 4, characterized in that the outer plate (20) and the baffle plate (30) are joined together to form a composite part.

6. Filter element according to one of claims 1 to 5, characterized in that between the raised edges (24) of the inlet nozzles (22) has a fluid-holding collecting volume (26) for dripping from the vapor fluid from the first filter stage (18) and the second filter stage ( 32) is formed.

7. Filter element according to one of claims 1 to 6, characterized in that the second filter stage (32) comprises a clean air side arranged outer layer (34) and one of the baffle plate (28) adjacent, wavy executed inner layer (36), wherein the waves of the inner layer (36) are arranged perpendicular to the alignment of the slots in the baffle plate and to align the inlet nozzles (22).

8. Filter element according to one of claims 1 to 7, characterized in that the baffle plate (28) is formed with stampings for holding a gap between the slots (30) and the second filter stage (32).

9. Filter element according to one of claims 1 to 8, characterized in that the filter frame (12) forms a part of the outer plate (20).

10. Filter element according to claim 9, characterized in that the filter frame (12) by deep drawing or bending on the outer plate (20) is formed.