EP3358260B1 - Extractor hood with filter element - Google Patents

Description

The present invention relates to an extractor device with at least one filter element.

From the DE 10 2013 218 419 A1 and the EP 2 857 758 A1 a fume extraction device is known which comprises a blower which is at least partially surrounded by a housing and in which at least one filter element forms at least part of at least one blower blade of the blower. In particular, this document describes an axial machine, which can also be referred to as an axial fan, with air-permeable blades. The filter element can comprise both fat filter and odor filter material, for example the fat filter can be mixed with an odor filter material, in particular activated carbon, wetted or otherwise connected. Alternatively, an odor filter element and a grease filter element can be provided in the extractor device.

A disadvantage of the known extractor device is that the filter rate on the odor filter element and the fat filter element are different.

The flow that flows through the filter element is also referred to as the secondary flow or filter volume flow. The main flow generated by the blower is referred to as the delivery volume flow. The ratio of filter volume flows to the delivery volume flow is referred to as the filter rate.

It is therefore an object of the present invention to provide an extractor device in which the filter performance of the individual filter types in the extractor device can be improved in a simple manner and in particular the filter rate of the various filter elements can be adapted.

The object is achieved by an extractor device which has a housing and a rotor arranged in the housing with at least one rotor blade, which is formed at least in regions by a filter element, the rotor blade comprises at least one fat filter element and at least one odor filter element which are adjacent to one another in the axial direction of the rotor blade, characterized in that the fat filter element is adjacent to the leading edge of the blade and the odor filter element is adjacent to the trailing edge of the rotor blade and the length of the fat filter element is greater than the length of the odor filter element.

According to the invention, an extractor device is a device by means of which at least some of the contaminants can be removed from vapors and vapors. Vapors and vapors are also referred to below as polluted air. Liquid and particulate impurities and odorous substances are particularly preferably removed from the vapors and vapors by means of the extractor device according to the invention. According to the invention, the extractor device is understood to mean the entire device by means of which the impurities are removed. The extractor device can be installed in an extractor hood or be configured as an extractor hood.

According to the invention, the extractor hood device has at least one housing and a rotor arranged in the housing. The housing and the rotor are also referred to as blowers. The fan particularly preferably represents an axial fan. According to the invention, the housing is an at least partially closed container for influencing the flow in the extractor device. The housing preferably has a cylindrical shape and is open at the top and bottom. The top is also referred to as the clean air side and the bottom as the inflow side. In particular, the air to be cleaned is moved by the fan in a direction parallel to the axis of the rotor, which is also referred to as the rotor hub. The housing preferably extends parallel to the rotor hub in a rotationally symmetrical manner around the latter. On the one hand, this prevents the radial escape of air from the fan and, on the other hand, the air is reliably guided in the housing.

Unless otherwise stated, directional indications, as above and below, relate to an extractor hood device and its components in the assembled state in which one side, in particular the underside of the extractor hood device, faces a cooktop located under the extractor hood device.

According to the invention, the rotor comprises at least one rotor blade. The at least one rotor blade is preferably attached to a rotor hub and extends radially outward from the rotor hub. A plurality of rotor blades are preferably provided on the rotor hub. The details of the rotor blades are described below using a rotor blade. The plurality of rotor blades preferably have the same structure. According to the invention, the at least one rotor blade is formed at least in regions by a filter element. The filter elements can be fastened in brackets or on connecting elements. Alternatively, the filter elements can preferably be held in one or more frames.

The extractor device is characterized in that the rotor blade comprises at least one grease filter element and at least one odor filter element which are adjacent to one another in the axial direction of the rotor blade. A grease filter element is a filter element that is designed to filter out liquid contaminants, such as grease and other liquids, from the contaminated air. For this purpose, the grease filter element has a certain blockage, via which the air is deflected several times. Here, the heavy particles, in particular fat particles, hit the filter material and are separated there. The grease filter element can consist, for example, of one or more expanded metal filters. However, other fat filter elements that function according to the principle of inertia can also be used. The odor filter element preferably consists of a material on which odor substances can separate or on which these can be bound. The odor filter element preferably has activated carbon as the filter material. The vapor must strike the surface of the filter material, in particular the activated carbon, or flow along it. Depending on the structural design, the tightness or the grain size of the activated carbon, the characteristic of the pressure loss in the air flowing through the odor filter element is different.

As a rule, the pressure losses at the grease filter element and the odor filter element are different at the same inflow velocities. In particular, the pressure loss at the odor filter element is generally higher than at the fat filter element, the difference increasing with increasing flow velocity. Due to the different pressure losses of the filter media of the Fat filter element and the odor filter element result in different sized secondary flows through the rotor blades with the same filter division, that is, with the same size of the filter area of the different filter elements. This is reflected in different filter rates.

By suitable geometries of the blower and in particular of the rotor blade, the pressure applied to the rotor blade or blades can be higher, in particular in the outflow region of the housing. Since the fat filter element and the odor filter element are adjacent to one another in the axial direction according to the invention, the geometry of the housing can be set such that a higher pressure is applied to the rotor blade in the area in which the odor filter is located.

The axially offset arrangement of the odor filter element and the fat filter element enables the filter rate on the individual filter elements to be set in a targeted manner.

According to the invention, the grease filter element is adjacent to the leading edge of the blade and the odor filter element is adjacent to the trailing edge of the rotor blade. The leading edge of the blade is the axial end of the rotor blade which faces the upstream side of the housing, in particular the underside of the housing, in the assembled state of the extractor device. The trailing edge is the opposite axial end of the rotor blade, which faces the outflow side and in particular the top of the housing in the assembled state of the extractor device. The grease filter element is thus arranged in the lower area of the rotor blade and fumes and vapors are first passed through these grease filter elements. This removes grease and other liquid contaminants from the contaminated air before it reaches the odor filter element. Contamination, in particular clogging of the odor filter element displaced axially upward by grease or other liquid contaminants can thus be prevented.

According to a preferred embodiment, the rotor blade has a hub ratio di / da in the range from 0.4 to 0.6. The total pressure that can be built up depends on the circumferential speed, i.e. the radius and speed. If the hub ratio is too small, i.e. the inner diameter is small, that is The peripheral speed is also very low and not enough pressure is built up. By using a rotor blade with such a hub ratio, which is defined by the diameter of the rotor hub and thus the inside diameter of the rotor blade to the outside diameter of the rotor, a sufficiently high total pressure can be built up in the turbomachine. Sufficiently describes the necessary static pressure via the rotor blade and your filter media in order to reliably establish the secondary flow or the filter volume flow. In this way, the secondary flow or the filter volume flow can also be reliably established.

According to a further embodiment, the rotor preferably has a ratio of the length of the rotor blade to the outside diameter of the rotor of greater than 1. The length of the rotor blade is understood in particular to mean the length of the center line of the rotor blade in the axial direction, which can also be referred to as a skeleton line. This length can be greater than the height of the rotor blade, that is to say its axial dimension.

According to a preferred embodiment, the at least one rotor blade represents a twisted blade. A twisted blade is understood in particular to be a blade that extends in a spiral around the rotor hub. The contact surface of the blade on the rotor axis therefore represents a spiral shape or part of a spiral. In this embodiment, the rotor blade can extend straight from the rotor axis in the radial direction. The twisted shape of the rotor blade can on the one hand cause the incoming air to swirl around the rotor axis. On the other hand, the passage of air through the rotor blade, in particular through the filter elements in the rotor blade, is favored in this form of the rotor blade.

According to the invention, the rotor blade can thus have an axial curvature. Additionally or alternatively, the rotor blade can also have a radial curvature. A radial curvature here is a curvature of the blade in the radial direction. The flow against the rotor blade can be further supported by an additional radial curvature.

In the case of a rotor blade that has an axial curvature, the length of the center line of the rotor blade is greater than the axial height of the rotor blade.

The length of the rotor blade is large due to the ratio of the length of the rotor blade to the outer diameter of the rotor, which is preferably greater than 1. A large length of the rotor blades increases the surface area of the blades and thus also the surface of the filter elements. This reduces the speed at which the air has to pass through the filter elements. The ratio of the length of the rotor blade to the outer diameter of the rotor is particularly preferably in the range from 1.2 to 1.5.

According to a preferred embodiment, the degree of reaction of the blade, expressed by the ratio of the static pressure increase to the total pressure increase in the fan, is greater than 80%. Static pressure is understood here to mean the pressure difference from the suction to the pressure side of the rotor blade and thus across the filter element. The total pressure is the sum of static pressure and dynamic pressure. A high degree of reaction ensures that the pressure difference at the blade is as large as possible in order to push a lot of medium through the filter element.

According to the invention, the length of the fat filter element is greater than the length of the odor filter element. The length of the filter element is understood to mean the dimension of the respective filter element along the skeleton line of the rotor blade. A larger part of the rotor blade is thus formed by the grease filter element. However, since a greater pressure can prevail in the fume extraction device according to the invention by suitable choice of the geometric dimensions and the degree of reaction in the area of the outflow side of the housing, adequate filtering of odorous substances can nevertheless be ensured, although the area covered by the odor filter is smaller than that Area covered by the grease filter element.

According to one embodiment, the dividing line between the fat filter element and the odor filter element is in the range from 55 to 70% of the length of the rotor blade.

According to one embodiment, the fat filter element and the odor filter element are held in a common frame. This simplifies the entire structure the extractor hood. The frame can surround the filter elements at their edges. However, it is also within the scope of the invention that support structures for the respective filter elements are provided in the frame. As a result, the shape of the rotor blade can be reliably generated even when using dimensionally unstable filter material, for example granular activated carbon, and can also be maintained during operation of the extractor device.

Figur 1:

eine schematische Perspektivansicht einer Ausführungsform der erfindungsgemäßen Dunstabzugsvorrichtung;

Figur 2:

eine schematische Ansicht einer Ausführungsform einer Rotorschaufel der Dunstabzugsvorrichtung;

Figur 3:

eine schematische Ansicht der Ausführungsform der Rotorschaufel ohne Filterelemente; und

Figur 4:

eine schematische Darstellung der Strömungen an einer Rotorschaufel.

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

Figure 1:

a schematic perspective view of an embodiment of the extractor device according to the invention;

Figure 2:

a schematic view of an embodiment of a rotor blade of the extractor device;

Figure 3:

a schematic view of the embodiment of the rotor blade without filter elements; and

Figure 4:

a schematic representation of the flows on a rotor blade.

In Figure 1 An embodiment of an extractor device 1 according to the invention is shown. In the illustrated embodiment, the extractor device 1 comprises a housing 2 and a rotor 40. The housing 2 together with the rotor 40 forms the fan 4. The housing 2 represents a cylindrical housing. The housing 2 is open at the top and bottom thereof. Air flows through the housing 2, which flows into the fume extraction device 1 in a main flow direction S from below. The underside of the housing 2 and thus the extractor hood device 1 is therefore referred to as the inflow side A and the top side as the clean air side R. In the top and bottom of the housing 2, an anti-tamper grille 21 is provided. The lateral surface of the housing 2 is formed in the embodiment shown by a housing wall 23, which forms part of the circumference of the housing 2, and a housing frame 20 and doors 22. In the illustrated embodiment two doors 22 are provided which can be pivoted outwards relative to the housing wall 23. The housing 2 is in Figure 1 in an open state, in which the doors 22 are pivoted outwards. According to the invention, the housing 2 can also be formed by a cylindrical housing wall (not shown) in which no doors are provided.

A rotor 40 is provided in the interior of the housing 2. In the embodiment in Figure 1 the rotor 40 is completely accommodated in the housing 2. The rotor 40 consists of a rotor hub 42 and rotor blades 41 fastened to the rotor hub 42. The view in FIG Figure 1 three of the rotor blades 41 can be seen. In the illustrated embodiment, the rotor blades 41 each consist of a grease filter element 30 and an odor filter element 31, which are connected to one another and to the rotor hub 42 via a connecting element 33. The rotor blades 41 are attached to the rotor hub 40 such that they have an angle of attack α. This angle α represents the angle that is spanned between the surface of the rotor blade 41 and the rotor hub 42.

In the illustrated embodiment, each of the filter elements 30, 31 has an intertwined shape, which means that the filter element 30 and the filter element 31 each have a curvature in their height, that is to say in the axial direction. In the illustrated embodiment, the rotor blades 41 have no curvature in the radial direction.

The fat filter element 30 is arranged in the lower region of the rotor blade 41, that is to say forms the lower part of the rotor blade 41. The odor filter element 31 is arranged in the upper region of the rotor blade 41, that is to say forms the upper part of the rotor blade.

The lower edge of the grease filter element 30 is in the illustrated embodiment in the immediate vicinity of the lower anti-tamper grille 21 and the upper edge is held in the connecting element 33. The upper edge of the odor filter element 31 lies in the illustrated embodiment in the immediate vicinity of the upper anti-tamper grille 21 and the lower edge is held in the connecting element 33.

The length of the rotor blade is in Figure 1 schematically indicated by the skeleton line L.

The operation of the extractor device 1 according to the invention will now be described in more detail. The rotor hub 42 is driven or rotated by a motor (not shown). Rotation of the rotor hub 42 also rotates the rotor blades 41 with the rotor hub 42. As a result, the air entering the housing 2 via the inflow side A is set in a spiral movement. This forms 2 pressure conditions in the housing, in which there is a pressure difference between the two surfaces of a rotor blade 41. In particular, there is a lower pressure on the upper surface than on the lower surface of the rotor blades 41. Since the rotor blades 41 are formed at least in regions by the filter elements 30, 31 and these are permeable to air, air can pass through the filter elements 30, 31 and thus through the rotor blades 41. The passage of air through the filter elements 30, 31 is further supported by the existing pressure difference. The passage of the air through the filter elements 30, 31 removes impurities from the air.

How out Figure 1 results in the illustrated embodiment, the length of the grease filter element 30 is greater than the length of the odor filter element 31, that is, the dividing line formed by the connecting element 33 is seen from the underside of the extractor device at a height which is greater than half the height of the rotor and is also greater than half the length of the rotor blades.

In Figure 2 Another embodiment of a rotor blade is shown, which instead of the in Figure 1 rotor blades shown can be used. In this embodiment of the rotor blade, too, more than one, for example three, rotor blades are preferably provided on the rotor hub.

In the embodiment according to Figure 2 the grease filter element 30 and the odor filter element 31 are held in a filter frame 32. In the embodiment shown, this extends around all edges of the respective filter elements 30, 31. In the embodiment shown, the fat filter element 30 consists of expanded metal layers. The odor filter element 31 is an activated carbon filter. There is a dividing line in the filter frame 32 provided along which the filter frame separates the odor filter element 31 from the grease filter element 30.

In Figure 3 is the filter frame 32 of the Figure 2 without filter elements 30, 31 shown. In this view, support structures 34 in the form of support grids with a large mesh size can be seen.

In Figure 4 the pressure conditions on the rotor blade 41 are shown schematically. Flow vectors are indicated schematically by the arrows. In the Figure 4 a rotor blade 41 with an asymmetrical structure is shown. In particular, the length of the fat filter element 30 is greater than the length of the odor filter element 31. The dividing line between the fat filter element 30 and the odor filter element 31 is closer to the trailing edge of the rotor blade 41 than to the front edge of the rotor blade 41. In the area of the odor filter element 31 there is a greater pressure on the rotor blade than in the area of the grease filter element.

With the present invention, a solution can thus be created by means of which the functional production and optimization of the filter performance of an axial blower, which can also be referred to as a fan, with porous rotor blades, which can also be referred to as airfoils, taking into account the delivery volume capacity of the fan / Blower becomes possible.

In particular, in the present invention, a long, elongated rotor blade is used in the extractor device, which can also be referred to as a turbomachine.

The present invention has a number of advantages. In particular, a functional and optimal filter performance can be generated in an extractor device, in particular an extractor device with an axial fan with air-permeable rotor blades.

The described invention enables filter rates of> 1.5 to 2. This means based on the delivery volume, which is similar or better to a normal air circulation hood, the delivered air is sucked through the filter several times.

This process in the above-mentioned axial design is much more energy efficient than with a conventional extractor hood.

Reference list

1

Extractor hood

2nd

casing

20

Housing frame

21

Protection grille

22

door

23

Housing wall

30th

Grease filter element

31

Odor filter element

32

Filter frame

33

Fastener

34

Support structure

4th

fan

40

rotor

41

Rotor blade

42

Rotor hub

α

Angle of attack

S

Main flow direction

A

Upstream side

R

Clean air side

L

Skeletal line

T

parting line

Claims (8)

1. Extractor device, which has a housing (2) and a rotor (4) arranged in the housing (2) with at least one rotor blade (41), which at least in regions is formed by a filter element (30, 31), wherein the rotor blade (41) comprises at least one fat filter element (30) and at least one odour filter element (31), which lie adjacent to one another in the axial direction of the rotor blade (41), characterised in that the fat filter element (30) is adjacent to the blade leading edge and the odour filter element (31) is adjacent to the trailing edge of the rotor blade (41) and the length of the fat filter element (30) is greater than the length of the odour filter element (31).
2. Extractor device according to claim 1, characterised in that the rotor blade (41) has a hub ratio, di/da, in the range of 0.4 to 0.6.
3. Extractor device according to one of claims 1 or 2, characterised in that the rotor (4) has a ratio of the length of the rotor blade (41) to the external diameter of the rotor (4) of greater than 1, preferably in the range of 1.2 to 1.5.
4. Extractor device according to one of claims 1 to 3, characterised in that the degree of reaction of the rotor blade (41) is expressed by the ratio of the static pressure increase to the total pressure increase in the housing (2) of greater than 80%.
5. Extractor device according to one of claims 1 to 4, characterised in that the dividing line (T) between fat filter element (30) and odour filter element (31) lies in the range of 55 to 70% of the length of the rotor blade (41).
6. Extractor device according to one of claims 1 to 5, characterised in that the fat filter element (30) and the odour filter element (31) are retained in a common filter frame (33).
7. Extractor device according to one of claims 1 to 6, characterised in that the fat filter element (30) represents an expanded metal filter element.
8. Extractor device according to one of claims 1 to 7, characterised in that the odour filter element (31) represents an activated carbon filter element.

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