Air filter device and vehicle air conditioning unit equipped with it

Abstract

The present invention relates to an air filter device (1) through which a flow path (30) for an airflow leads. It has an ionizer (10) arranged in the flow path (30) and an electrostatically charged filter element (20) arranged downstream of the ionizer (10) in the flow path (30), such that the ionizer (10) and the filter element (20) are permeable to the airflow. Furthermore, the ionizer (10) has an electrode (11) electrically connectable to a high-voltage source (4) of the air filter device (1) for generating a corona discharge, a counter electrode (15) associated with the electrode (11), and an electrically conductive grid element (40) arranged upstream of the ionizer (10) in the flow path (30). Essential to the invention is that the counter electrode (15) is electrically connected to an electrically conductive, planar filter layer (21) of the filter element (20) and to the grid element (40).The invention relates in particular to a vehicle air conditioning unit (2) with at least one such air filter device (1).

Description

[0001] The invention relates to an air filter device according to the preamble of claim 1. The invention further relates to a vehicle air conditioning unit equipped with at least one air filter device.

[0002] An air filter device of the type described above is known from WO 2020 263 171 A1. Further air filter devices are described in EP 3 056 364 B1, US 20 210 021 107 A1, WO 2021 226 639 A2, KR 102 205 159 B1, EP 3 488 933 A1 and US 2016 229 267 A1.

[0003] Air filter devices of the aforementioned type are designed to clean air of pollutants such as particulate matter, harmful gases, and unpleasant odors. They are used particularly in vehicle air conditioning systems, where they primarily clean outside air that is drawn into the passenger compartment. This ensures a comfortable and healthy indoor climate with high air quality in the passenger compartment.

[0004] Urban areas pose a challenge for such air filtration systems. The outdoor air there can contain exceptionally high and potentially hazardous levels of particulate matter. For example, in large cities, levels of particulate matter are known to significantly exceed the daily average PM100 recommended by the World Health Organization. 2.5 of 15 µg / m³ 3 Such conditions place high demands on air filter devices; in particular, they should be able to ensure a high filter separation efficiency for corresponding particles in such urban areas over the longest possible maintenance-free operation.

[0005] To achieve this, manufacturers of air filtration systems have begun imprinting an electrostatic charge on the filter elements during their production. This allows particles carried in the ambient air to be separated from the filter element not only mechanically, but also through electrostatic effects. This electrostatic separation is particularly effective in reliably removing even the smallest particles, especially fine dust particles, from the air.

[0006] Unfortunately, the electrostatic charge imparted to a filter element weakens over time, particularly with increasing aging of the filter element and / or with increasing charge buildup. This reduces the proportion of electrostatic deposition, which in modern filters often constitutes the largest share of the total deposition.

[0007] Corona discharge ionizers are used to enhance the electrostatic deposition of the filter element. These ionizers generate a corona discharge (positive or negative polarity), which produces electrons and ions that ionize gas molecules. The ionized gas molecules then bind to particles carried in the airflow, thus improving the electrostatic deposition of the filter element. However, conventional air filter devices may no longer meet the required filtration performance after a certain period of operation. This necessitates early maintenance and, if necessary, replacement of the filter element. If this does not occur, vehicle occupants may be exposed to high levels of particulate matter, depending on the age of the filter.

[0008] The object of the invention is therefore to provide an improved or at least a different embodiment of an air filter device. In particular, a vehicle air conditioning unit with at least one such air filter device is to be provided.

[0009] In the present invention, this problem is solved in particular by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims and the description.

[0010] The invention has recognized that the separation efficiency of a filter element and the service life of the filter element can be increased by improved polarization of the air filter device in combination with optimized ionization / particle charging.

[0011] Accordingly, an air filter device is proposed, in particular a vehicle cabin air filter device for a vehicle air conditioning unit, through which an airflow path leads. The air filter device has an ionizer arranged in the airflow path for ionizing the airflow and an electrostatically charged filter element arranged downstream of the ionizer in the airflow path for filtering the airflow, such that the ionizer and the filter element are permeable to the airflow.Furthermore, the ionizer is provided to have at least one electrode, electrically connectable or connected to a high-voltage source of the air filter device, for generating a corona discharge in the airflow; at least one counter electrode associated with the at least one electrode; and an electrically conductive, planar grid element arranged upstream of the electrode and counter electrode in the flow path, which expediently acts as a counter electrode. It is essential that the at least one counter electrode is electrically connected to an electrically conductive, planar filter layer of the filter element and to the grid element.The air filter device is designed so that an electric field is generated between the ionizer and the filter element during operation. This significantly improves the filter element's separation efficiency through polarization phenomena and extends its service life, even as it ages. The upstream grid element, which conveniently acts as a counter electrode for at least one electrode, enhances the electrostatic charging of the particles carried in the airflow. This, in combination with the polarization effect, further improves the filter element's separation efficiency.

[0012] The expert understands that the aforementioned ionization of the airflow means nothing other than an electrostatic charging of the gas molecules in the air as well as the particles carried in the airflow.

[0013] It is advantageous if, during operation of the air filter device, a first electrical potential can be applied to at least one electrode (e.g., by means of the high-voltage source), and a second electrical potential, different from the first, can be applied to at least one counter electrode, the filter layer, and the grid element. This creates an electric field between the ionizer (which, as mentioned, consists of at least one electrode, the counter electrode, and the grid element) and the filter element during operation. Since the potential of the counter electrodes is also present at the filter element, a polarization effect can be achieved within the filter element. This effect can significantly increase the filtration efficiency of the filter element, even if it has already aged.

[0014] Furthermore, it is possible for the first electrical potential to be a supply potential and the second electrical potential to be a counter-potential. In particular, a reverse solution is conceivable, where the first electrical potential is a counter-potential and the second electrical potential is a supply potential. The first electrical potential can be a negative high-voltage potential, in which case the counter-potential is a positive counter-potential. Alternatively, it is conceivable that the first electrical potential is a positive high-voltage potential, while the counter-potential is a negative counter-potential.

[0015] Advantageously, it is provided that during operation of the air filter device, a negative or positive potential difference (voltage potential) is applied or can be applied between the at least one electrode on the one hand and the at least one counter electrode, the filter layer, and the grid element on the other. This potential difference is advantageously determined by the difference between the first electrical potential and the second electrical potential.

[0016] In particular, it can be provided that the voltage or potential difference is in the range of -5 kV to -11 kV, or preferably -7 kV. This allows at least one electrode to generate a negative corona discharge, which, compared to a positive corona discharge, leads to improved ionization of the particles carried in the airflow and thus to better separation efficiencies by the air filter device. However, the air filter device can also be configured and operated such that at least one electrode generates a positive corona discharge in the airflow.

[0017] Advantageously, the ionizer can be arranged to have a first distance of 0 mm to 30 mm, preferably 7 mm, from the downstream filter element. Furthermore, the at least one electrode can have a second distance of 20 mm to 50 mm, preferably 30 mm, from the upstream grid element. This achieves ionization in the air filter device, which charges particles in the airflow. This also generates an advantageous polarization effect in the filter element. In combination, these effects ensure high particle separation. At the same time, the air filter device has a compact design in the specified areas, so that the installation space dimensions required for use in a vehicle air conditioning unit can be met.The invention has recognized in particular that if the distance between the ionizer and the filter element is 7 mm and the distance between the ionizer and the grid element is 30 mm, a better ratio can be achieved between, on the one hand, the improved particle separation efficiency and, on the other hand, the size of the air filter device.

[0018] The grid element preferably has a mesh size in the range of 1 mm to 6 mm and preferably 3 mm. In this invention, "mesh size" expediently refers to the clear distance between two adjacent grid nodes of the grid element. The grid element can further have a mesh area in the range of 1 × 1 mm. 2 up to 6×6 mm 2 and preferably 3×3 mm 2 The mesh area refers to the surface area of ​​a mesh opening in the grid element. Furthermore, it may be specified that the grid element is made of stainless steel to ensure durability.

[0019] Furthermore, it may be advantageous for the filter element to have a layer for particle separation. This layer is advantageously made of a weakly electrically conductive or an electrically insulating material. In particular, it can generate an electrostatic field.

[0020] It is advantageous if this layer (hereinafter referred to as the dielectric layer) is arranged on the filter element's upstream side, facing the ionizer and the airflow. This places the dielectric layer upstream of the filter layer with respect to the airflow, and therefore it is flushed with air before reaching the filter layer. The dielectric layer is preferably the particle-separating layer of the filter element.

[0021] Furthermore, the filter layer may include or be composed of an activated carbon layer. Such a filter layer reliably removes harmful gases and unpleasant odors carried in the airflow. The activated carbon layer is preferably positioned downstream of the dielectric layer with respect to the airflow.

[0022] Furthermore, it is advantageous if the filter element is pleated, i.e., folded.

[0023] Various designs are conceivable for the at least one electrode and the at least one counter electrode. However, it is advantageous if the at least one electrode has a pointed (needle- or cone-shaped) electrode body that defines a central axis, and if the at least one counter electrode has an annular or circular cylindrical counter electrode body that defines an internal volume. The electrode body can be arranged relative to the counter electrode body such that its central axis is parallel and preferably coaxial with a central axis of the counter electrode body. The electrode body can be located substantially entirely or completely within the internal volume of the counter electrode body. Furthermore, a tip of the needle- or cone-shaped electrode body can face the airflow.Furthermore, it may be advantageous if the diameter of the counter electrode body is in the range of 40 mm to 90 mm, or preferably 50 mm. Additionally, if a consistent availability of the at least one electrode and the at least one counter electrode is to be ensured, it may be provided that the electrode body and the counter electrode body are made of stainless steel. Furthermore, the grid element that acts as the counter electrode may also preferably be made of stainless steel.

[0024] The air filter device advantageously comprises two or more electrodes and two or more counter electrodes, each associated with one of the electrodes, wherein the electrodes and counter electrodes are electrically conductively connected. Furthermore, the air filter device may have at least one additional electrode and at least one additional counter electrode associated with the at least one additional electrode. The at least one electrode and the at least one additional electrode are electrically conductively connected. The at least one counter electrode and the at least one additional counter electrode may also be electrically conductively connected. The air filter device thus comprises an arrangement of at least two electrodes and an arrangement of at least two counter electrodes, each associated with one of the at least two electrodes.It may further be provided that the air filter device has a plurality of electrodes and a plurality of counter electrodes, wherein the counter electrodes are electrically connected to each other, and wherein the counter electrodes are each assigned to one electrode.

[0025] According to a further aspect of the invention, a vehicle air conditioning unit is provided, which is installed in a vehicle and configured for air conditioning the passenger compartment of the vehicle. Crucially, it is equipped with at least one air filter device as described above. This provides an advantageous vehicle air conditioning unit which, due to the installed at least one air filter device in the passenger compartment, can maintain a climate with high air quality over a comparatively long operating period.

[0026] In summary, the present invention preferably relates to an air filter device through which a flow path for an airflow passes. It comprises an ionizer arranged in the flow path and an electrostatically charged filter element arranged downstream of the ionizer in the flow path, such that the ionizer and the filter element are permeable to airflow. Furthermore, the ionizer has an electrode electrically connectable to a high-voltage source of the air filter device for generating a corona discharge, a counter electrode associated with the electrode, and an electrically conductive grid element arranged upstream of the electrode in the flow path, which preferably acts as an additional counter electrode. Crucially, the counter electrode is electrically connected to an electrically conductive, planar filter layer of the filter element and to the grid element.The invention relates in particular to a vehicle air conditioning unit with at least one such air filter device.

[0027] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0028] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0029] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0030] They show, each schematically Fig. 1 a simplified perspective view of a preferred embodiment of an air filter device and Fig. 2 the air filter device Fig. 1 in a sectional view.

[0031] The Fig. 1 and Fig. Figure 2 shows a preferred, simplified embodiment of an air filter device designated in its entirety by reference numeral 1, which is preferably designed as a vehicle cabin air filter device and is installed in a housing 3 of a vehicle air conditioning unit 2 of a vehicle not illustrated.

[0032] In the Fig. 1 and Fig. 2. The air flows through the air filter device 1 in the direction indicated by arrows 30. Specifically, this is an airflow of outside air, recirculated air, or a mixture of outside and recirculated air, which is drawn in from the environment surrounding the vehicle and directed into a passenger compartment (not illustrated). The airflow carries unwanted particles, harmful gases, and unpleasant odors, which are to be removed from the airflow by the air filter device 1. For this purpose, the air filter device 1 is provided with an ionizer 10 arranged in the flow path 30 for ionizing the airflow and an electrostatically charged filter element 20 arranged downstream of the ionizer 10 in the flow path 30 for filtering the airflow. Based on the Fig. 1 and Fig. 2 shows that the airflow passes completely through the ionizer 10 and the filter element 20.

[0033] The ionizer 10 of the air filter device 1 has several electrodes 11 lying in a common plane, each configured to generate a corona discharge. They each have needle- or cone-shaped electrode bodies 12, which are arranged in Fig. 1 and Fig. 2 are symbolized by simple points. The electrode bodies 12 each define a central axis 13 in their respective principal direction of extension and also each have a point 14 facing the airflow, see Fig. 2. Furthermore, it is planned that the electrodes 11 will be selected using a method described in Fig. 1 and Fig. 2 drawn, first electrical conductor 5 with a in Fig. 1 and Fig. The high-voltage source 4 of the air filter device 1, indicated by a simple box, is electrically connected. The high-voltage source 4 is designed to apply an electrical potential to the electrodes 11.

[0034] The ionizer 10 has, in addition to the electrodes 11, several counter electrodes 15, which lie in a common plane and are each assigned to one electrode 11. The counter electrodes 15 each have an annular or hollow cylindrical counter electrode body 16 with a clear diameter 17 in the range of D = 40 mm to D = 90 mm, or preferably D = 50 mm. Furthermore, the counter electrode bodies 16 each define an internal volume 26. For reasons of durability, the counter electrode bodies 16, like the electrodes 11, are also made of stainless steel. Fig. 1 and Fig.As shown in Figure 2, the counter electrodes 15 and the electrodes 11 are arranged such that the electrode bodies 12 are each located centrally with respect to a counter electrode body 16 and are substantially or completely within a respective internal volume 26 of a counter electrode body 16. The electrode bodies 12 are advantageously aligned within the respective internal volume 26 such that their central axes 13 are parallel and, in particular, coaxial with respect to the central axes 35 defined by the counter electrode bodies 16.

[0035] The ionizer 10 of the air filter device 1 further comprises a grid element 40, which is flat in shape and arranged upstream of the electrodes 11 in the flow path 30. This grid element is made of an electrically conductive material such as stainless steel. By way of example, it has a mesh size in the range of 1 mm to 6 mm, and preferably 3 mm, so that the airflow can pass through it in a fluid-mechanical manner. Furthermore, it acts as an additional counter electrode, which ensures effective ionization of the particles in the airflow.

[0036] The filter element 20 of the air filter device 1 can be pleated and / or made in one piece. In this case, it has a layered structure comprising an electrically conductive filter layer 21 and a dielectric layer 22 for particle separation. Further layers are conceivable. The filter layer 21 can have an activated carbon layer or be entirely composed of it. The dielectric layer 22 is advantageously made of a weakly electrically conductive or an electrically insulating material and is arranged on the filter element upstream side 23 of the filter element 20, facing the ionizer 10 and the airflow, on the filter layer 21. This places the dielectric layer 22 upstream of the filter element 21 with respect to the airflow direction 30, and it is therefore flushed with air before reaching the filter layer 21.

[0037] The ionizer 10 is arranged with respect to the filter element 20 such that a first distance 36 in the range of 0 mm to 30 mm, preferably 7 mm, is set between them.

[0038] Furthermore, the grid element 40 is arranged with respect to the electrode tips 14 such that a second distance 41 (H1) is set between them in the range of H1=20 mm to H1=50 mm, preferably H1=30 mm.

[0039] The minimum distance 44 (H2) between the counter electrodes 15 and the electrodes 11 in the direction (arrow 30) of the airflow is equal to or greater than half the inner diameter of the electrode bodies 16, e.g. it is H2=20 mm to H2=45 mm, best it is H2=25 mm.

[0040] Essential to the invention is that the counter electrodes 15 are electrically connected to the electrically conductive filter layer 21 of the filter element 20 and to the grid element 40, which acts as an additional counter electrode, by means of a second electrically conductive conductor 6. This makes it possible for the electrodes 11 to be supplied with a first electrical potential 33 by means of the high-voltage source 4 during operation of the air filter device 1, while a second electrical potential 34, different from the first electrical potential 33, can be applied to or is applied to the counter electrodes 15, the filter layer 21, and the grid element 40. For example, the first electrical potential 33 can be a supply potential and the second electrical potential 34 a counter potential. The latter is realized in this case by connecting the second electrical conductor 6 to a counter potential point 7.This preferably results in a potential difference between the first electrical potential 33 and the second electrical potential 34, which can be in the range of -5 kV to -11 kV or preferably at -7 kV.

[0041] This achieves the following: During operation of the air filter device 1, the airflow passes through the air filter device 1, whereby unwanted particles such as fine dust, pollutants, and unpleasant odors are carried past the ionizer 10. The electrodes 11 are subjected to the first electrical potential 33, resulting in a potential difference of, for example, -7 kV between the electrodes 11 and the counter electrodes 15, the filter layer 21, and the grid element 40. This generates corona discharges in the airflow in the immediate vicinity of the electrode tips 14, electrostatically ionizing gas molecules. The ionized gas molecules then bind to the particles carried in the airflow, so that these can also be considered electrostatically charged. The counter electrodes 15, the filter layer 21, and the grid element 40, all of which are at opposite potential, form an opposite potential to the electrodes 11.This creates an electrostatic field between the electrodes 11 and the filter element 20 during operation of the air filter device 1. This electric field polarizes the filter element 20. This leads to an increase in the precipitation of charged particles due to corona discharge particle charge and electrostatic polarization phenomena within the filter element layer. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2020 263 171 A1

[0002] EP 3 056 364 B1

[0002] US 20 210 021 107 A1

[0002] WO 2021 226 639 A2

[0002] KR 102 205 159 B1

[0002] EP 3 488 933 A1

[0002] US 2016 229 267 A1

[0002]

Claims

[1] Air filter device (1), in particular a vehicle cabin air filter device for a vehicle air conditioning unit (2), - through which a flow path (30) for an air flow leads, - wherein the air filter device (1) has an ionizer (10) arranged in the flow path (30) for ionizing the air flow and an electrostatically charged filter element (20) arranged in the flow path (30) downstream of the ionizer (10) for filtering the air flow, so that the ionizer (10) and the filter element (20) can be flowed through by the air flow, - wherein the ionizer (10) has at least one electrode (11) which is electrically connected or conductively connectable to a high-voltage source (4) of the air filter device (1) for generating a corona discharge in the air flow, at least one counter electrode (15) associated with the at least one electrode (11), and an electrically conductive and flat grid element (40) arranged in the flow path (30) upstream of the at least one electrode (11), characterized by , that - the at least one counter electrode (15) is electrically conductively connected to an electrically conductive, flat filter layer (21) of the filter element (20) and to the grid element (40). [2] Air filter device (1) according to claim 1, characterized by , that - during operation of the air filter device (1), a first electrical potential (33) can be applied or is applied to the at least one electrode (11) and a second electrical potential (34) different from the first electrical potential (33) can be applied or is applied to the at least one counter electrode (15), the filter layer (21) and the grid element (40). [3] Air filter device (1) according to claim 1 or 2, characterized by , that - the first electrical potential (33) is a supply potential and the second electrical potential (34) is its counter potential, or vice versa. [4] Air filter device (1) according to one of the preceding claims, characterized by , that - during operation of the air filter device (1), a negative or positive potential difference is applied or can be applied between the at least one electrode (11) on the one hand and the at least one counter electrode (15), the filter layer (21) and the grid element (40) on the other hand. [5] Air filter device (1) according to claim 4, characterized by , that - the negative potential difference is in the range of - 5 kV to - 11 kV or preferably - 7 kV. [6] Air filter device (1) according to one of the preceding claims, characterized by , that - the ionizer (10) has a first distance (36) in the range from 0 mm to 30 mm, preferably 7 mm, from the downstream filter element (20), and / or - the electrodes (11) have a second distance (41) in the range of 20 mm to 50 mm, preferably 30 mm, from the upstream grid element (40). [7] Air filter device (1) according to one of the preceding claims, characterized by , that - the filter element (20) has a dielectric layer (22). [8] Air filter device (1) according to claim 7, characterized by , that - the dielectric layer (22) is arranged on the filter layer (21) on a filter element inflow side (23) of the filter element (20) facing the ionizer (10) and the air flow. [9] Air filter device (1) according to one of the preceding claims, characterized by , that - the filter layer (21) comprises or is formed by an activated carbon layer. [10] Air filter device (1) according to one of the preceding claims, characterized by , that - the at least one electrode (11) has a needle- or conical-shaped electrode body (12) which defines a central axis (13), - the at least one counter electrode (15) has an annular or hollow cylindrical counter electrode body (16) which delimits an internal volume (26), - wherein the electrode body (12) is arranged relative to the counter-electrode body (16) such that the center axis (13) of the electrode body (12) is parallel and preferably coaxial with a center axis (35) of the counter-electrode body (16), - wherein the electrode body (12) is arranged substantially completely or entirely in the inner volume (26) of the counter electrode body (16) and - wherein a tip (14) of the needle- or conical-shaped electrode body (12) faces the air flow. [11] Air filter device (1) according to one of the preceding claims, characterized by , that - two or more electrodes (11) and two or more counter electrodes (15) are provided, each associated with the electrodes (11), - wherein the electrodes (11) are electrically conductively connected to one another, - wherein the counter electrodes (15) are electrically conductively connected to one another. [12] Vehicle air conditioning unit (2) of a vehicle with at least one air filter device (1) according to one of the preceding claims.

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