Air filtering device and motor vehicle

Abstract

The invention relates to an air filter device and a motor vehicle, in particular an electrostatic air filter device for a motor vehicle (1), comprising: a flow channel (7) for conducting an air flow (5); an ionization device (9) for ionizing particles carried in the air flow (5), having at least one corona electrode (10) and at least one counter electrode (11) in the flow channel (7); and a filter element (8) for filtering particles from the air flow (5), which filter element is arranged downstream of the ionization device (9) in the flow channel (7) and has a multi-layer filter body (13) with at least one particle filter layer (14) and at least one electrically conductive layer (15). The separation performance of the air filter device (9) can be improved, in particular with respect to the duration, in that the at least one electrically conductive layer (15) is electrically connected to the at least one counter electrode (11) via an electrical resistor (16).

Description

Technical Field

[0001] This invention relates to an electrostatic air filtration device according to the preamble of claim 1, preferably an electrostatic air filtration device for a motor vehicle. The invention also relates to a motor vehicle equipped with such an air filtration device. Background Technology

[0002] To ensure comfortable and healthy air quality, the air located in the vehicle's interior space or passenger compartment and supplied to the passenger compartment is decontaminated with pollutants such as fine dust, harmful gases such as hydrocarbons and nitrogen oxides, and unpleasant odors such as ammonia, trimethylamine, and hydrogen sulfide. A significant problem, especially in Asian urban spaces, is the high level of fine dust in the outside air. In large cities, the daily average fine dust load often exceeds the PM2.5 value or 15 µg / m³ set by the World Health Organization. 3 The daily average. Nowadays, the removal of dust entering the vehicle interior through fresh air systems is typically achieved using filter elements arranged within the fresh air system. These filter elements can be designed as particulate filters, mixed filters, or a combination filter with both particulate and activated carbon filters. The particulate filter has a fiber filter layer for removing particles. This filter element is crucial for the air quality inside the vehicle.

[0003] In fresh air systems that typically include air conditioning, only a small amount of structural space is available for filter elements. Often, the air conditioning system and the filter are housed in a common housing. Therefore, these filter elements must have low flow resistance and / or pressure loss, while still ensuring a predetermined airflow can be delivered into the vehicle's interior space, thus meeting safety requirements such as preventing windshield fogging. This has the disadvantage that the particle filter layer for separating particles is typically made extremely porous, and therefore the mechanical dust removal efficiency of the filter element is usually very low. Therefore, many filter media and / or filter fiber layer manufacturers ensure that the filter media is electrostatically charged during production. This allows for better separation of particles, which are usually also electrostatically charged, through electrostatic separation of the filter media during subsequent operation. This separation mechanism can also separate very small particles <0.3 μm without increasing the flow resistance and / or pressure loss of the filter element. However, as the filter element ages and due to the increased dust load during operation, the electrostatic charge applied during production quickly becomes ineffective. Therefore, the electrostatic charge of the filter element is primarily effective only at the beginning of its lifespan. Depending on the level of external air pollution, a significant decrease in static electricity may occur within weeks or months.

[0004] So-called ionizers or ionization devices use the mechanism of electrostatic charging of particles. With regard to the air flow upstream of the filter element, the ionizer or ionization device charges the particles contained in the air flow. In addition, the filter element is also slightly charged by the ions introduced into the air. This ensures an increase in the separation of the particles by means of the electrostatic particle separation, which is maintained over a longer period of time, in addition to the purely mechanical separation performance of the filter element.

[0005] In order to charge the particles, the ionization devices used usually have a negative transmission or corona electrode for generating a corona discharge. In the case of a negative corona discharge, electrons occur on the corona electrode, which usually has a series of multiple pointed contours, for example in the form of very sharp spikes or needles, and the electrons are strongly accelerated, inter alia, in the near field of the corona electrode. The electrons then collide with gas molecules, whereby the gas molecules lose further electrons by collision and are thereby positively ionized. A positive gas molecule or gas ion and two electrons are thus generated. This effect occurs mainly in very high field strengths, in short distances from the corona electrode. In greater distances from the corona electrode, the fast-moving electrons mainly accumulate on the gas molecules and thereby form negative gas ions. More gas ions are formed in a negative corona discharge than in a positive corona discharge, since the electrons migrate more quickly due to their small size. This favors the charging of the particles and thus also the separation in the subsequent filter element.

[0006] Positive and negative ions are thus generated in the gas flow or air flow, which in turn accumulate on the particles. However, the net charge is always negative for a negative corona discharge, since electrons are introduced into the air flow.

[0007] The electrostatic charging of the filter element decreases with increasing load or operating time, since the electrostatic charge or electrostatic charging of the filter element is also lost due to the dust layer on the filter element.

[0008] For example, a generic electrostatic air filter device is known from US 5 403 383 A. The electrostatic air filter device works together with a flow channel for guiding an air flow and has an ionization device for ionizing particles carried in the air flow, which has a corona electrode and a counter electrode in the flow channel. In addition, a particle filter element is provided for filtering out particles from the air flow, which is arranged downstream of the ionization device in the flow channel and has a filter body with a particle filter layer and an electrically conductive layer in multiple layers. In the known air filter device, the counter electrode and the electrically conductive layer are each electrically connected with a zero potential. SUMMARY

[0009] The invention relates to the problem of improved embodiments of ionization devices of the type mentioned at the outset or of air filter devices equipped with ionization devices or of motor vehicles equipped with air filter devices, which are characterized, inter alia, by a high separation of particles even in the case of an aged state of the filter element.

[0010] According to the invention, this problem is solved by the subject matter of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.

[0011] The invention is based on the general idea that the respective electrically conductive layer of the filter element is electrically connected to the respective counter electrode by means of a resistor, whereby on the one hand it is achieved that the respective electrically conductive layer and the respective counter electrode are on the same electrical potential. This results in that the electrostatic charging of the particle filter element can be continuously regenerated. On the other hand, however, by the proposal according to the invention, the current flow to the particle filter element is significantly reduced. An excessively high current flow results in that too much current flows to the filter element and less ionization for charging the particles takes place. Thus, an optimum balance between ionization and regeneration of the filter element is achieved with the resistor, and thus an optimum continuous filter separation performance is achieved by means of the ionization device. At the same time, the possibility of the undesired formation of ozone within the air filter device is thereby reduced. Furthermore, with the same current consumption, more electrical energy is available for the ionization, whereby, in addition, the separation or filter action of the air filter device can be improved.

[0012] In particular, for this purpose, an electrostatic air filter device is proposed, which has a flow channel for guiding an air flow, an ionization device for ionizing particles carried in the air flow and a filter element for filtering out the particles from the air flow. The ionization device has at least one corona electrode and at least one counter electrode in the flow channel. The filter element is arranged downstream of the ionization device in the flow channel and has a filter body with at least one particle filter layer and at least one electrically conductive layer. It is now essential to the invention that the at least one electrically conductive layer is electrically connected to the at least one counter electrode via a resistor, preferably via an ohmic resistor.

[0013] Since the filter element is arranged downstream of the ionization device in the flow channel, all electrodes of the ionization device are located upstream of the filter element.

[0014] The filter element can be designed at least as a particle filter, so that the filter element has at least at least one particle filter layer. Preferably, however, the filter element is a hybrid filter or a combination filter, which has at least one particle filter layer and at least one activated carbon filter layer.

[0015] The respective resistor can be formed here by a single resistor element or by a plurality of resistor elements which can be connected in series or in parallel.

[0016] The respective particle filter layer can suitably be configured electrically insulating and in particular dielectric.

[0017] According to an advantageous embodiment, the electrical resistance can be a high ohmic resistance. By designing the electrical resistance as a high ohmic resistance, the current flow to the conductive layer of the filter element is significantly reduced, whereby the electrical energy available for the ionization of particles is significantly increased, which improves the filtering action of the air filter device.

[0018] In the present connection, an ohmic resistance is in particular considered to be high ohmic if the associated resistance value is at least 500 times as large as the voltage present in the system or network. In this case, the respective high ohmic resistance value can thus be at least 500 times as large as the high voltage used in the ionization device. In a high voltage of for example 10 kV, the high ohmic resistance thus has a resistance value of at least 5 MOhm.

[0019] According to an advantageous embodiment, the electrical resistance can be arranged in an electrical connection which electrically connects the at least one conductive layer directly with the at least one corresponding electrode. In other words, it is proposed here to connect the respective conductive layer from the electrical contact point constructed on the filter element with the respective corresponding electrode using an electrical connection and via a high ohmic resistance. The electrical connection can here be a connection line or a cable or a printed circuit board or the like.

[0020] In an advantageous embodiment, the electrical resistance can have a resistance value in the range of 10 MOhm to 100 MOhm.

[0021] Suitably, the electrical resistance can have a resistance value of at least 10 MOhm or at least 15 MOhm or at least 20 MOhm or at least 25 MOhm.

[0022] Additionally or alternatively, the electrical resistance can in particular have a resistance value of at most 100 MOhm or at most 90 MOhm or at most 40 MOhm or at most 35 MOhm.

[0023] It proves to be particularly advantageous to be the following embodiment, in which the electrical resistance has a resistance value of approximately 30 MOhm, i.e. a resistance value of 30 MOhm ± 10%, so that the resistance value is in particular in the range of 27 MOhm to 33 MOhm.

[0024] In other advantageous embodiments, it can be provided that the electrical resistance has a resistance value which is at least 500 times as large as the high voltage present on the at least one corona electrode in the operation of the ionization device. In a high voltage of 10 kV, the resistance value of the electrical resistance is thus at least 5 MOhm.

[0025] Suitably, the ionization device can be configured for generating a corona discharge at the respective corona electrode and / or for applying a high voltage at the corona electrode, wherein the high voltage is at least 5 kV or at least 6 kV or at least 10 kV or at least 15 kV.

[0026] In the present context, "configuring" is synonymous with "designing" and / or "equipping" and / or "programming", such that the expression "configured to" is synonymous with the expression "designed and / or equipped and / or programmed to".

[0027] The ionization device can be equipped with a high-voltage generator for generating the high voltage, to which the respective corona electrode and the respective counter electrode are electrically coupled. Preferably, each corona electrode and each counter electrode is electrically connected with the high-voltage generator.

[0028] The motor vehicle according to the application comprises a vehicle interior and an air conditioning installation for air-conditioning an air flow to be conveyed into the vehicle interior. The air conditioning installation is equipped with an air filter device of the type described above.

[0029] Further important features and advantages of the present application result from the dependent claims, the figures and the related figure description based on the figures.

[0030] It is to be understood that the features mentioned above and those to be explained below can be used not only in the combinations indicated, but also in other combinations or in isolation, without departing from the scope of the application defined by the claims. The above-mentioned and below-to-be-explained individual components of an upper unit, such as a device, an apparatus or an arrangement, can form individual components or parts of this unit or can be integral areas or sections of this unit, even if this is not shown differently in the figures. BRIEF DESCRIPTION OF DRAWINGS

[0031] Preferred embodiments of the present application are shown in the drawings and explained in more detail in the following description, in which the same reference signs denote identical or similar or functionally identical parts.

[0032] Unique Figure 1 A very simplified, line diagrammatic, schematic representation of a motor vehicle is shown in the region of the air filter device. DETAILED DESCRIPTION

[0033] According to Figure 1 The only partly shown motor vehicle 1 comprises a vehicle interior 2 and an air conditioning installation 3, which is configured such that fresh air from the environment 4 of the vehicle 1 and / or from the vehicle interior 2 can be conveyed to the vehicle interior 2 by means of the air conditioning installation 3. Thereby, an air flow 5 is constituted, which is to be air-conditioned by the air conditioning installation 3. The air conditioning installation 3 comprises an air filter device 6 of the type described above, which is arranged in the air flow 5 and which is configured to filter the air flow 5. Figure 1The air flow 5 is shown by arrows. The air conditioning installation 3 comprises an electrostatic air filter device 6, which has a flow channel 7, which is in Figure 1 which is limited upwards and downwards by dashed lines. The air filter device 6 is here integrated into the air conditioning installation 3, so that the air flow 5 also flows through the flow channel 7.

[0034] The electrostatic air filter device 6 comprises a flow channel 7 for guiding the air flow 5 and a filter element 8 arranged in the flow channel 7, so that the air flow 5 flows through the filter element 8. The air filter device 6 is also equipped with an ionization device 9, by means of which particles carried in the air flow 5 can be ionized in order to improve the accumulation of the particles in the filter element 8. The filter element 8 can here be electrostatically charged, inter alia, in order to improve the accumulation of the ionized particles.

[0035] The air conditioning installation 3 serves for air conditioning of the air flow 5 and can here be equipped in a customary manner with a cooler, not shown here, and / or a heater, not shown here, so that the air flow 5 can be cooled or heated as required and, if necessary, dried. Suitably, the air conditioning installation 3 is configured so that the air conditioning of the air flow 5 takes place downstream of the filter device 6 with respect to the flow direction of the air. Suitably, the air filter device 6 is mounted into a housing, not shown here, of the air conditioning installation 3.

[0036] The ionization device 9 has at least one corona electrode 10 and at least one counter electrode 11 in the flow channel 7 upstream of the filter element 8. In Figure 1 two corona electrodes 10 are shown purely by way of example, which cooperate with two counter electrodes 11. The respective corona electrode 10 and the respective counter electrode 11 are arranged in the flow channel 7 upstream of the filter element 8. In a plurality of corona electrodes 10 and a plurality of counter electrodes 11, all corona electrodes 10 and all counter electrodes 11 are suitably arranged in the flow channel 7 upstream of the filter element 8.

[0037] The respective corona electrode 10 and the respective counter electrode 11 are arranged in the flow channel 7 so that they can be flowed around by the air flow 5. During operation of the ionization device 9, the corona electrode 10 and the counter electrode 11 generate an electric field 12, which propagates between the respective corona electrode 10 and the respective counter electrode 11 and, in Figure 1 is shown in dashed lines. Particles flowing in the air flow 5 through this field 12 are thereby ionized.

[0038] The filter element 8 has a multi-layer filter body 13 with at least one particle filter layer 14 and at least one electrically conductive layer 15. The layers 14, 15 can here be folded in order to increase the available filter surface in a familiar manner. The electrically conductive layer 15 can be formed by electrically conductive fibers or metal wires and is placed onto the respective particle filter layer 14. It is also conceivable that the electrically conductive layer 15 is configured as an activated carbon layer which has activated carbon particles and is preferably arranged or structured downstream of the particle filter layer 14. In this case, the filter element 8 is designed as a hybrid filter. It is also possible in a hybrid filter or combination filter that, in addition to the particle filter layer 14 and the activated carbon layer, an electrically conductive layer 15 can also be provided.

[0039] According to Figure 1 , the respective electrically conductive layer 15 is electrically connected to the respective corresponding electrode 11 by means of a resistance 16. The resistance 16 is preferably configured as an ohmic resistance 16. Advantageously, the resistance 16 is a high ohmic resistance 16. In Figure 1 the example, the resistance 16 is arranged in an electrical connection 17 which electrically connects the respective electrically conductive layer 15 directly to the respective corresponding electrode 11. The respective electrically conductive layer 15 is thus not directly earthed and also not directly connected to a zero potential. It is clear that the electrical connection 17 is preferably electrically connected to an electrical contact point which is constructed on the filter element 8 and which is electrically connected to the respective electrically conductive layer 15 in an appropriate manner inside the filter element 8.

[0040] The resistance 16 can have a resistance of at least 10 MOhm or at least 15 MOhm or at least 20 MOhm or at least 25 MOhm. The resistance 16 can additionally or alternatively also have a resistance of at most 50 MOhm or at most 45 MOhm or at most 40 MOhm or at most 35 MOhm. The resistance of the resistance 16 can thus be in particular in the range from 10 MOhm to 100 MOhm, or in the range from 15 MOhm to 45 MOhm, or in the range from 20 MOhm to 40 MOhm, or in the range from 25 MOhm to 35 MOhm, with the narrower ranges being more preferred than the wider ranges. It has proven to be particularly advantageous for the resistance of the resistance 16 to be in the range from 27 MOhm to 33 MOhm, i.e. 30 MOhm ± 10%, and in particular 30 MOhm.

[0041] The ionization device 9 is operated in operation with a high voltage, which is present on the respective corona electrode 10 during operation of the ionization device 9. To this end, the ionization device 9 can be equipped with a high-voltage generator 18, which is electrically coupled on the one hand to the respective corona electrode 10 and on the other hand to the respective counter electrode 11. The ionization device 9 can be configured to provide a high voltage of at least 5 kV or at least 6 kV or at least 10 kV or at least 12 kV or at least 13 kV or at least 15 kV. In particular, the ionization device 9 can thus be configured to generate a corona discharge at the respective corona electrode 10. In the corona discharge, a field 12 is formed, which can also be referred to as a corona field 12 or a discharge field 12 or a corona discharge field 12.

[0042] According to a preferred design, the resistance 16 can have a resistance value that is at least 500 times as large as the high voltage present at the respective corona electrode 10 in operation of the ionization device 9. Thus, in the case of a 15 kV high voltage, the resistance value is at least 10 MOhm.

[0043] List of reference signs

[0044] 1 motor vehicle

[0045] 2 vehicle interior

[0046] 3 air conditioning system

[0047] 4 environment

[0048] 5 air flow

[0049] 6 air filtration device

[0050] 7 flow channel

[0051] 8 filter element

[0052] 9 ionization device

[0053] 10 corona electrode

[0054] 11 counter electrode

[0055] 12 field

[0056] 13 filter body

[0057] 14 particle filter layer

[0058] 15 conductive layer

[0059] 16 resistance

[0060] 17 electrical connection

[0061] 18 high-voltage generator

Claims

1. Electrostatic air filter device (6), in particular for a motor vehicle (1), having - a flow channel (7) for guiding an air flow (5), - ionization means (9) for ionizing particles carried in the air flow (5), the ionization means having at least one corona electrode (10) and at least one counter electrode (11) in the flow channel (7), and - a filter element (8) for filtering the particles from the air flow (5), the filter element being arranged downstream of the ionization means (9) in the flow channel (7) and having a filter body (13) with at least one particle filter layer (14) and at least one electrically conductive layer (15), characterized in that - the at least one electrically conductive layer (15) is electrically connected to the at least one counter electrode (11) by means of a resistance (16).

2. Air filter device (6) according to claim 1, characterized in that - the resistance (16) is a high-ohmic resistance (16).

3. Air filter device (6) according to any one of the preceding claims, characterized in that - the resistance (16) is arranged in an electrical connection (17) which directly electrically connects the at least one electrically conductive layer (15) to the at least one counter electrode (11).

4. Air filter device (6) according to any one of the preceding claims, characterized in that - the resistance (16) has a resistance in the range of 10 MOhm to 50 MOhm, or - the resistance (16) has a resistance in the range of 15 MOhm to 45 MOhm, or - the resistance (16) has a resistance in the range of 20 MOhm to 40 MOhm, or - the resistance (16) has a resistance in the range of 25 MOhm to 35 MOhm.

5. Air filter device (6) according to any one of the preceding claims, characterized in that - the resistance (16) has a resistance of at least 10 MOhm, or - the resistance (16) has a resistance of at least 15 MOhm, or - the resistance (16) has a resistance of at least 20 MOhm, or - the resistance (16) has a resistance of at least 25 MOhm.

6. Air filter device (6) according to any one of the preceding claims, characterized in that - the resistance (16) has a resistance of at most 100 MOhm, or - the resistance (16) has a resistance of at most 90 MOhm, or - the resistance (16) has a resistance of at most 80 MOhm, or - the resistance (16) has a resistance of at most 70 MOhm.

7. Air filter device (6) according to any one of the preceding claims, characterized in that - the resistance (16) has a resistance of 30 MOhm.

8. Air filter device (6) according to any one of the preceding claims, characterized in that ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ - the resistor (16) has a resistance which is at least 500 times as large as the high voltage present on the at least one corona electrode (10) in operation of the ionization device (9).

9. Air filter device (6) according to any one of the preceding claims, characterized in that - the ionization device (9) is configured to generate a corona discharge on the respective corona electrode (10) and / or to provide a high voltage of at least 5 kV on the corona electrode (10).

10. Motor vehicle (1) having - a vehicle interior (2), - an air conditioning system (3) for air conditioning of an air flow (5) to be conveyed to the vehicle interior (2), - wherein, the air conditioning system (3) being equipped with an air filter device (6) according to any one of the preceding claims.

Images