Air cleaning method and heating, ventilation and air conditioning system

Abstract

The invention relates to an air cleaning method and a heating, ventilation and air conditioning system. A heating, ventilation and air conditioning system has an ionization device for generating a corona discharge field, the ionization device having a corona onset electrode of electrical polarity and a mating electrode of opposite electrical polarity with respect to the corona onset electrode; a particulate filter for removing particulates from the airflow; and an air path which prescribes a flow direction in which air is guided to the interior of the vehicle and which guides the air through an ionization device (3) and the particulate filter, the ionization device being arranged upstream of the particulate filter in the air path. The ionization effect can be improved if the respective corona electrode (6) has a plurality of needles (20) oriented in or against the flow direction (11) of the air and the respective corona electrode (6) is spaced apart from the associated counter electrode (7) transversely to the flow direction (11) of the air.

Description

Technical Field

[0001] The invention relates to an air cleaning method for a heating, ventilation and air conditioning system for a motor vehicle. The invention also relates to a heating, ventilation and air conditioning system for a motor vehicle according to the preamble of claim 6. Background Art

[0002] Heating, ventilation and air conditioning systems are also commonly referred to as HVAC systems, where HVAC stands for Heating, Ventilation and Air Conditioning.

[0003] Such an HVAC system is known, for example, from EP 3 056 364 B1 and comprises an ionization device for generating a corona discharge field, which has at least one corona induction electrode of electrical polarity and at least one counter electrode of electrical polarity opposite to the corona induction electrode. The HVAC system also has a particle filter for removing particles from the air flow. Finally, the HVAC system has an air path, which predetermines the flow direction of air to the interior of the vehicle and which guides the air through the ionization device and the particle filter. Here, the ionization device is arranged upstream of the particle filter in the air path. In the known HVAC system, the counter electrode is columnar and the corona induction electrode is arranged concentrically with the columnar counter electrode and oriented parallel to its longitudinal center axis.

[0004] Other HVAC systems utilizing ionization are known from EP 3 488 933 A1, KR 10-2205159 B1, US 2021 / 0021 107 A1, WO 2020 / 263171 A1 and WO 2021 / 226639 A2.

[0005] Such HVAC systems are mainly used for relatively small available space for particle filters and at the same time expect to obtain a high filtering effect with a large air volume requirement over a long time interval. A high filtering effect can be achieved by a correspondingly smaller pore size in the particle filter. However, as the pore size decreases, the flow resistance of the particle filter increases. In order to compensate for this, the surface of the particle filter through which flow can flow can be increased. However, the increase in the filter surface is limited by the available structural space. In particular, in areas with a high fine dust load, a particle filter with a sufficiently small pore size can only achieve the desired air volume requirement or filtering effect in a short time, because it will quickly become clogged with increasing load and the flow resistance increases to an impermissibly high level. With the help of a particle filter that is electrostatically charged within its manufacturing range, these particles can be filtered out of the air flow even in the case of a larger pore size if these particles are ionized in advance. The particles adhere to the charged filter material by electrostatic attraction. The ionization of the particles is achieved using an ionization device. In this case, an electrostatic field is generated between a corona initiation electrode and a counter electrode, which is called a corona discharge field. In this case, the corona initiation electrode is preferably of negative polarity, while the counter electrode is positive or grounded. The corona discharge is generated at the tip of the negative polarity corona initiation electrode, which results in the generation of a large number of high-speed electrons, which move towards the opposite electrode. When these electrons hit the gas molecules in the air flow, other electrons are either separated or accumulated on the gas molecules. In the first case, new free electrons and positive gas ions appear, and in the second case, negative gas ions appear. In principle, this gas ionization also works in the case of polarity reversal, that is, using a positive polarity corona initiation electrode and a negative polarity matching electrode.

[0006] The particle charging is achieved by gas ions and begins as the particles enter the corona discharge space through the jet flow. If the gas ions collide with the particles, the particles are charged by the accumulation of gas ions on the particles. The charging process is achieved by field charging and diffusion charging.

[0007] However, it has been found that the electrostatic charge of the original factory particle filter is reduced by the particle load, so that the filtering effect of the particle filter decreases significantly after a short service life. To compensate for this, the replacement interval of the particle filter can be significantly shortened, but this will result in relatively high costs. Summary of the invention

[0008] The object of the present invention is to specify an improved or at least different embodiment for an HVAC system or an air cleaning method of the type mentioned above, which is characterized in particular by a higher filtering effect at larger air volumes over a longer service life.

[0009] According to the invention, this problem is solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0010] The air cleaning method according to the invention for an HVAC system of a motor vehicle is based on the general idea that a particle filter is polarized with the aid of an electric field in order to electrostatically charge it. According to the invention, the electric field required for this is generated with the aid of an ionization device. Thus, an ionization device that is already present can advantageously be used for an additional function. The polarization of the particle filter causes an electrostatic charging of the particle filter in order to improve the filtering effect for particles. In particular, the electrostatic charge of the particle filter that was electrostatically charged at the factory can be regenerated. In other words, the polarization of the particle filter corresponds to the regeneration of the particle filter.

[0011] According to an advantageous embodiment, it can be provided that the particle filter is equipped with at least one conductive layer, which is set to a potential with an opposite electrical polarity to the corona induction electrode, so that an electric field is generated between the ionization device and the particle filter during the operation of the ionization device. The particle filter can be polarized by the electric field between the ionization device and the particle filter. Therefore, the electric field can also be called a polarization field. By polarizing the particle filter, the electrostatic charge of the particle filter is regenerated to a certain extent. As a result, a higher filtering effect is achieved to a certain extent for a larger air volume within the predetermined service life or use time of the particle filter. The corresponding potential can be provided on the conductive layer of the particle filter as follows, that is, the conductive layer is electrically contacted or electrically connected to a matching potential, which is opposite in electrical polarity to the corona induction electrode.

[0012] According to an advantageous embodiment, it can be provided that the conductive layer is only connected to the matching potential until the polarization of the particle filter reaches a predetermined polarization limit value. When the predetermined polarization limit value is reached, the respective conductive layers of the particle filter are electrically separated from the matching potential. In addition or alternatively, in another embodiment, it can be provided that the conductive layer is only connected to the matching potential until the predetermined polarization time ends. When the predetermined polarization time ends, the respective conductive layers of the particle filter are electrically separated from the matching potential. In this case, the time is thus monitored. There is no need to monitor the polarization for this purpose. These measures are based on the recognition that, after the particle filter is successfully polarized, the electrostatic charge of the particle filter thus achieved only decreases slowly during the operation of the HVAC system, i.e., due to the particles filtered out of the air flow. As a result of the separation from the matching potential, it is no longer necessary to create and maintain an electric field between the ionization device and the particle filter, whereby the ionization device requires less electrical power. The HVAC system can thus operate efficiently.

[0013] During the generation of the electric field for polarizing the particle filter, the ionization device operates with relatively high electrical power. At high power, ozone is also generated in the air flow. As the respective conductive layers separate from the matching potential, the electrical power of the ionization device also decreases, so that less ozone is generated, which is beneficial for the ozone load in the vehicle interior.

[0014] According to an advantageous improvement to the air cleaning method, it can be provided that the conductive layer is only separated from the matching potential until the polarization of the particle filter reaches a predetermined depolarization limit value. In other words, the electrostatic charge of the particle filter is monitored. If it is below the depolarization limit value, polarization is performed in order to restore the electrostatic charge. This restoration or polarization can be repeated as often as desired to a certain extent. When the predetermined depolarization limit value is reached, the conductive layer of the particle filter is electrically connected to the matching potential again. Thus, repolarization or regeneration of the particle filter is performed. Additionally or alternatively, in another embodiment, it can be provided that the conductive layer is only separated from the matching potential until the predetermined depolarization time ends. After the depolarization time ends, the conductive layer of the particle filter is electrically connected to the matching potential again. Therefore, in this case, the monitoring time. For this purpose, it is not necessary to monitor the polarization.

[0015] The polarization time and / or depolarization time depends on the intended application for the respective particle filter, wherein in particular conditions such as the size of the particle filter, the filter effect to be achieved thereby and / or the air volume and the fine dust load at the respective location of use of the particle filter may be taken into account.

[0016] In principle, the embodiment with positive polarity of the corona initiation electrode and negative polarity of the counter electrode and the counter potential can be advantageous. However, the embodiment with negative polarity of the corona initiation electrode and positive polarity of the counter electrode and the counter potential is preferred. In this case, the ionization works particularly effectively.

[0017] According to an advantageous embodiment, it can be provided that the counter electrode is electrically connected to a counter potential, in particular permanently, and that the electrically conductive layer of the particle filter is electrically connected to the counter electrode in order to electrically connect the electrically conductive layer to the counter potential. This embodiment is particularly easy to implement.

[0018] The HVAC system according to the invention is based on the general idea that the respective corona induction electrode is equipped with a plurality of needles which are oriented in the direction of the air flow or against the direction of the air flow. Here, the needles protrude from the needle holder in the direction of the air flow or against the direction of the air flow. Here, the needles can extend obliquely or parallel to the flow direction. Here, the respective corona induction electrode and the associated counter electrode are arranged in the air path at intervals from each other transversely to the flow direction of the air.

[0019] In an advantageous embodiment, the respective corona induction electrode has a plurality of inflow-side needles which extend in the flow direction and point away from the particle filter. The tips of the needles therefore point away from the particle filter.

[0020] According to an advantageous embodiment, the respective corona induction electrode has a plurality of needles on the outflow side, which extend in the flow direction and are aligned with the particle filter. In the case where the needles on the outflow side are aligned with the particle filter, the tips of the needles face the particle filter. Although an embodiment in which the respective corona induction electrode has needles on the inflow side and needles on the outflow side is preferred, an embodiment in which there are no needles on the inflow side or needles on the outflow side is also feasible.

[0021] If a plurality of inflow-side needles and a plurality of outflow-side needles are provided, a preferred configuration is one in which the inflow-side needles have a predetermined identical spacing from one another on the inflow side of the needle holder. Likewise, the outflow-side needles have a predetermined identical spacing from one another on the outflow side of the needle holder, which spacing is as large as the spacing between adjacent inflow-side needles. In addition, it is advantageous that the inflow-side needles are arranged centrally along the needle holder between two outflow-side needles on the needle holder.

[0022] According to an advantageous embodiment, the respective counter-electrodes can be designed as plates, preferably flat plates. The plate-like counter-electrodes can extend parallel to the respective corona initiation electrodes. The respective plates are flat, and their thickness is small compared to the plate length and plate width. For example, the respective plates are arranged in the air flow as follows, that is, the plate width extends parallel to the flow direction of the air, while the plate length and plate thickness extend transversely to the flow direction of the air, respectively. Therefore, the air only flows through the narrow edge of the plate-like counter-electrodes. Additionally or alternatively, it can be provided that the respective corona initiation electrodes and the corresponding counter-electrodes extend straightly and preferably transversely to the flow direction of the air, respectively. An effective corona discharge field can be generated by this structural method to achieve effective ionization of particles carried in the air flow. In addition, this configuration is relatively small with respect to the flow direction of the air.

[0023] According to an advantageous embodiment, at least one conductive layer can be provided in the particle filter and configured such that it can be electrically connected to a matching potential, which is of opposite electrical polarity relative to the corona induction electrode. For this purpose, the HVAC system is equipped with an electrical connection, which is configured such that the respective conductive layer and the matching potential can be electrically connected or contacted by means of the electrical connection. In the simplest case, this can be achieved by a grounding cable which is electrically connected to the zero potential of the ionization device.

[0024] In conjunction with the above, "configured" is synonymous with "designed" and / or "programmed", so that the phrase "configured as follows" is equivalent to the phrase "designed and / or programmed as follows".

[0025] An embodiment in which the electrical connection is designed to be switchable is advantageous. As a result, the respective conductive layer can be connected to or disconnected from the matching potential as required. Thus, during operation of the ionization device, the particle filter can be polarized when the conductive layer is electrically connected to the matching potential in order to regenerate its static charge. When the static charge is sufficient, further polarization is terminated by disconnecting the connection to the matching potential in order to save electrical energy. The switchability of the connection can be realized, for example, by means of an electromechanical or electronic switch.

[0026] A particularly advantageous embodiment is that the HVAC system has a control device which is configured such that it carries out the above-described air cleaning method during operation of the HVAC system. In other words, the control device controls the controllable components of the HVAC system, namely in particular the ionization device and the switchable connection, in order to carry out the above-described air cleaning method.

[0027] The dielectric layer of the particle filter can be designed as a particle filter layer with or composed of a nonwoven fabric. In this case, the nonwoven fabric is usually made of plastic and is therefore dielectric. The nonwoven fabric can be produced in particular as a so-called blow-melt. The particle filter layer defines the pore size of the particle filter and is impermeable to particles whose particle size is larger than the pore size.

[0028] In another embodiment, the conductive layer of the particle filter is designed as an adsorption filter layer with activated carbon particles or composed of activated carbon particles. Since the activated carbon particles attached to each other are conductive, the adsorption filter layer as a whole is also conductive and can be used to form a polarization electric field through its grounding. The adsorption filter layer filters by adsorption, wherein the adsorption filter layer has an adsorption effect on gas molecules in particular. Here, the activated carbon particles can be attached to the nonwoven layer or held between two nonwoven layers.

[0029] Alternatively, the conductive layer of the particle filter can be designed as a grid structure, which has or consists of conductive wires or conductive fibers or conductive lines. Unlike the particle filter layer or adsorption filter layer, the grid structure has no significant filtering effect.

[0030] A suitable embodiment is that the respective dielectric layer is placed on the conductive layer and is in contact with it. In particular, the conductive layer extends over the entire extension of the respective dielectric layer. By this measure, the electric field generated by the grounding of the conductive layer also acts on the dielectric layer, so that in particular the dielectric layer can be polarized or electrostatically charged.

[0031] In this context, an arrangement has proven to be particularly advantageous in which the respective dielectric layer is arranged upstream of the respective conductive layer in the particle filter. This has the effect that the electrons and / or ions transported in the electric field and responsible for the electrostatic charge and polarization of the particle filter strike the dielectric layer on the way to the conductive layer and adhere there and cause the desired polarization.

[0032] Further important features and advantages of the invention are revealed in the dependent claims, in the drawings and in the accompanying description of the figures in conjunction with the drawings.

[0033] It should be understood that the features mentioned above and those to be explained below can be used not only in the respective given combination but also in other combinations or alone without departing from the scope of the invention as defined by the claims. The components mentioned above and those to be explained below of a separately marked higher-level unit (e.g., a device, a mechanism or a system) can form separate parts or components of the unit or be integral regions or parts of the unit, even if this is shown differently in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals designate identical or similar or functionally identical components.

[0035] The corresponding diagram is schematically shown in the figure:

[0036] Figure 1 A simplified schematic diagram showing an HVAC system with a particulate filter and an ionization device,

[0037] Figure 2 according to Figure 1 The section line II in FIG. 1 shows a simplified cross section of a particle filter.

[0038] Figure 3 According to Figure 1 The section line III in FIG. 1 shows a simplified cross section of the ionization device in the region of the electrode pair in different states a and b,

[0039] Figure 4 A simplified side view of the electrode pair according to FIG. 3 is shown according to viewing direction IV of FIG. 3 . Specific implementation plan

[0040] according to Figure 1 Furthermore, the HVAC system 1 of the motor vehicle 2 (not shown) comprises an ionization device 3, by means of which a corona discharge field 4 indicated by a dashed line in FIG. 3 can be generated. For this purpose, the ionization device 3 has at least one electrode pair 5, which has a negatively or positively polarized corona induction electrode 6 and a counter electrode 7 of opposite electrical polarity. Figure 1In the example of FIG. 3 , four such electrode pairs 5 are shown. Obviously, in another embodiment, more than two, in particular three or more such electrode pairs 5 can also be used. In particular, n corona induction electrodes 6 and n+1 counter electrodes 7 can be provided in the ionization device 3, so that each corona induction electrode 6 is arranged transversely to the flow direction 11 between two counter electrodes 7. In FIG. 3 , only two counter electrodes 7 are shown in each case for the sake of simplicity.

[0041] The respective corona induction electrode 6 (which can also be referred to as an emission electrode) is connected in a suitable manner to a high voltage source 8, which provides, for example, a DC voltage in the range of 5 kV to 10 kV, preferably about 7 kV. The counter electrode 7 is electrically connected in a suitable manner to a counter potential 9 of opposite electrical polarity with respect to the corona induction electrode 6. In the preferred case shown here, the respective corona induction electrode 6 is negatively polarized, while the associated counter electrode 7 is positively polarized. Therefore, the counter potential 9 is also positively polarized, which is Figure 1 and Figure 2 The diagram is simplified by using a ground symbol.

[0042] The HVAC system 1 also has a particle filter 10, which is configured to remove particles from an air flow 28, which is indicated by a wavy arrow in the figure. During operation of the HVAC system 1, the air flow 28 has a flow direction 11, which is indicated by an arrow in the figure. An air path 12 is formed in the HVAC system 1, which air path is Figures 1 to 4 1 is indicated by a dash-dotted line. The air path 12 illustrates the flow direction 11 of the air. Here, the air path 12 extends through the ionization device 3 and the particle filter 10. It is worth noting that the ionization device 3 is arranged upstream of the particle filter 10 in the air path 12 with respect to the air flow direction 11. The air path 12 leads the air to the vehicle interior 29 of the vehicle 2, which is not further shown. The air can be fresh air from the external environment of the vehicle 2 or recirculated air from the vehicle interior 29 or a mixture of fresh air and recirculated air.

[0043] according to Figure 1 and Figure 2 The particle filter 10 is configured as a multilayer in that it has at least one dielectric layer 13 and at least one conductive layer 14. The HVAC system 1 is also equipped with an electrical connection 15 for electrically connecting the respective conductive layer 14 to the matching potential 9. Figure 1 In accordance with an advantageous embodiment, the electrical connection 15 can be designed to be switchable. For example, the connection 15 can include a switch 16 for this purpose, with which the electrical contact between the conductive layer 14 and the matching potential 9 can be opened and closed as required. Figure 1In the example of FIG. 1 , the conductive layer 14 can be electrically connected to the corresponding matching electrode 7 via the connecting portion 15 . Therefore, the closing of the connecting portion 15 results in the conductive layer 14 being electrically connected to the matching potential 9 via the corresponding matching electrode 7 to a certain extent.

[0044] according to Figure 1 The HVAC system 1 may also be equipped with a control device 17, which can be connected to the high voltage source 8 and the switch 16 in a suitable manner (eg, via a control line 18). Here, the control device 17 may be configured to perform the air cleaning method described further below.

[0045] According to the air cleaning method, the particle-contaminated air flow 28 is first guided through the ionization device 3 according to the air path 12, and then through the multi-layer particle filter 10. Here, the ionization device 3 generates a corona discharge field 4 by means of the respective corona initiation electrode 6 and the corresponding counter electrode 7. The air flow 28 to be cleaned is guided through the corona discharge field 4. The particles carried in the air flow 28 are ionized in the corona discharge field 4. For the air cleaning method, the conductive layer 14 is also electrically connected or electrically contacted with the counter potential 9 via the electrical connection 15, so that an electric field 19 is generated between the ionization device 3 and the particle filter 10, which is shown in Figures 3 and 4. Figure 4 1 is indicated by a dashed line and is referred to below as a polarization field 19 . This polarization field 19 can achieve a polarization of the particle filter 10 , which ultimately leads to an electrostatic charging of the particle filter 10 .

[0046] According to an appropriate manner, the air cleaning method can be configured as follows, that is, the conductive layer 14 is only connected to the matching potential 9 until the polarization of the particle filter 10 reaches a predetermined polarization boundary value and / or until the predetermined polarization time ends. When the predetermined polarization boundary value is reached or when the predetermined polarization time ends, the conductive layer 14 of the particle filter 10 is electrically separated from the matching potential 9. This can be achieved by disconnecting the switch 16. During the filtering operation, the electrostatic charge of the particle filter 10 is reduced again due to the particles deposited thereon. In addition, the air cleaning method can be configured as follows, that is, the conductive layer 14 is only separated from the matching potential 9 until the polarization of the particle filter 10 (that is, its electrostatic charge) reaches a predetermined depolarization boundary value and / or until the predetermined depolarization time ends. When the predetermined depolarization boundary value is reached or when the depolarization time ends, the conductive layer 14 of the particle filter 10 is electrically connected to the matching potential 9 again. This can be achieved, for example, by closing the switch 16. In particular, it can be provided that the first electrical connection of the electrically conductive layer 14 to the matching potential 9 is not effected until the electrostatic charge of the particle filter 10 has reached a predetermined depolarization limit value and / or when a predetermined depolarization time has expired.

[0047] according to Figure 1 , Figure 3 and Figure 4, each corona induction electrode 6 can have a plurality of needles 20, which protrude from the needle holder 23 and have a tip 24 at its end away from the needle holder 23, which are only shown in FIG. 3 and Figure 4 In each electrode pair 5, the corona induction electrode 6 and the counter electrode 7 are spaced apart from each other transversely to the flow direction 11, so that the air path 12 can guide the air flow 28 to pass between the corona induction electrode 6 and the counter electrode 7. As long as a plurality of electrode pairs 5 are adjacent transversely to the flow direction 11, the corona induction electrode 6 can be arranged between two counter electrodes 7 and cooperate with the two counter electrodes 7 to form the corona discharge field 4.

[0048] According to FIG. 3 , the needles 20 of the respective corona induction electrodes 6 can extend parallel to the flow direction 11 . As a result, they protrude from the needle holder 23 in the flow direction 11 or in the opposite direction of the flow direction 11 . Figure 1 In FIG. 3 , the needle 20 is pin-shaped. Figure 4 In the embodiment of the present invention, they are cone-shaped or pyramid-shaped. Also conceivable are sheet-shaped needles 20 which taper gradually to form a needle tip 24.

[0049] according to Figure 1 , Figure 3 and Figure 4 , the respective corona induction electrodes 6 can have a plurality of outflow-side needles 21, which are aligned with the particle filter 10. In other words, these outflow-side needles 21 protrude from the needle holder 23 in the direction toward the particle filter 10. Therefore, the tips 24 of the outflow-side needles 21 face the particle filter 10. Preferably, the outflow-side needles 21 extend parallel to the flow direction 11 of the air.

[0050] In addition or instead of the needles 21 on the outflow side, the respective corona induction electrode 6 can have a plurality of needles 22 on the inflow side, which point away from the particle filter 10. In other words, the needles 22 on the inflow side protrude from the needle holder 23 in a direction away from the particle filter 10. The tips 24 of these needles 22 on the inflow side also face away from the particle filter 10. In a suitable manner, the needles 22 on the inflow side can extend parallel to the flow direction 11 of the air. The needles 22 on the inflow side are mainly used to generate the corona discharge field 4.

[0051] When a high voltage potential is applied to the corona induction electrode 6 and according to Figure 3a When the switch 16 is turned off, a corona discharge field 4 is formed between the corona initiation electrode 6 and the counter electrode 7, i.e., between the tips 24 of the needles 21 and 22 and the counter electrode 7. This electric field, i.e., the corona discharge field 4, is mainly responsible for electrostatically charging the particles in the air flow 28. Figure 3bWhen the switch 16 is turned on and connected to the counter electrode 7, the corona discharge field 4 is mainly formed between the corona initiation electrode 6 and the counter electrode 7, that is, between the tips 24 of the needles 21 and 22 and the counter electrode 7, wherein an electric field 19 is additionally formed between the tips 24 of the needles 21 on the outflow side and the filter element 10 (mainly the filter element layer 14). Here, the electric field 19 is mainly used for polarization or regeneration of the layer 13 of the filter element 10. When the switch 16 is turned on, the intensity of the electric field 19 is relatively strong, and when the switch 16 is turned off, the field intensity of the electric field 19 is relatively low.

[0052] The corona induction electrode 6 may be held on a dielectric high voltage insulator, which is Figure 1 The insulator is a part of the housing 34 of the HVAC system 1 shown or a separate unit arranged in the housing 34 of the HVAC system 1. Figures 1 to 4 Different shapes and different dielectric materials can be used for manufacturing the high-voltage insulator. The high-voltage insulator is used for electrical insulation of the corona induction electrode 6 relative to the matching electrode 7 (which has a matching potential or is grounded), or relative to the grounded housing 34 of the HVAC system 1, or relative to the grounded vehicle component, or relative to the grounded vehicle 2.

[0053] according to Figure 4 , the needles 22 on the inlet side have a predetermined spacing 31 between each other on the inlet side 30 of the needle holder 23. The needles 21 on the outflow side also have a predetermined spacing 33 between each other on the outflow side 32 of the needle holder 23. In an appropriate manner, the spacing 31 of adjacent needles 22 on the inlet side is the same as the spacing 33 of adjacent needles 21 on the outflow side. In addition, the configuration shown here is preferred, in which the needles 22 on the inlet side are arranged on the needle holder 23 centrally between two needles 21 on the outflow side along the needle holder 23, so that each needle 22 on the inlet side has half the spacing 31 or 33 with the needle 21 on the outflow side adjacent to it along the needle holder 23.

[0054] The respective counter electrode 7 can be designed in a suitable manner as a plate, which extends parallel to the respective corona induction electrode 6. In this case, the respective counter electrode 7 can be flat, i.e. designed as a flat plate. The corona induction electrode 6 and the counter electrode 7 can extend straight and parallel to each other, and in particular perpendicular to the flow direction 11 of the air. The respective needle holder 23 is configured, for example, as a straight rod. According to Figure 1 The counter electrodes 7 , which are designed as flat plates, extend parallel to one another and in a plane extending parallel to the flow direction 11 of the air flow 28 . The counter electrodes 7 are thus spaced apart from one another transversely to the flow direction 11 .

[0055] according to Figure 2, the dielectric layer 13 of the particle filter 10 can be designed as a particle filter layer 25, which is composed of at least one nonwoven fabric. In contrast, the conductive layer 14 of the particle filter 10 can be designed as an adsorption filter layer 26 with activated carbon particles. In addition or instead of such an adsorption filter layer 26, it can also be provided that the conductive layer 14 of the particle filter 10 is configured as a grid structure 27, which is formed by means of conductive metal wires or conductive fibers or conductive wires.

[0056] The conductive layer 14 is arranged on the dielectric layer 13 within the particle filter 10 and is in contact with it. In this case, the contact is preferably as large as possible. For this purpose, the conductive layer 14 can extend in particular over the entire outflow side or inflow side surface of the dielectric layer 13. Figure 2 In the example of , the particle filter 10 is pleated, wherein the conductive layer 14 follows the pleating of the dielectric layer 13 and is likewise pleated. The configuration shown here is preferred, in which the respective dielectric layer 13 is arranged upstream of the respective conductive layer 14 within the particle filter 10. In principle, however, an embodiment is also conceivable in which the respective dielectric layer 13 is arranged downstream of the respective conductive layer 14 within the particle filter 10.

[0057] It is obvious that the HVAC system 1 may also have a heater for heating the air flow 28 and a cooler for cooling and drying the air flow 28 .

Claims

1. An air cleaning method for a heating, ventilation and air conditioning system (HVAC system) (1) of a motor vehicle (2), wherein: - the particle-contaminated air flow (28) flows first through the ionization device (3) and then through the particle filter (10), - the ionization device (3) generates a corona discharge field (4) by means of at least one corona induction electrode (6) of an electrical polarity and at least one counter electrode (7) of an electrical polarity opposite to the corona induction electrode, - the air flow (28) to be cleaned is guided through the corona discharge field (4), thereby ionizing the entrained particles, The particle filter (10) is polarized by means of the ionization device (3) by generating an electric field (19) for polarizing the particle filter (10) by means of the ionization device (3).

2. The air cleaning method according to claim 1, It is characterized in that - the particle filter (10) is designed as a multi-layer particle filter (10) and has at least one dielectric layer (13) and at least one electrically conductive layer (14), The conductive layer (14) of the particle filter (10) is electrically connected to a matching potential (9) of opposite polarity to the corona induction electrode (6) in order to generate an electric field (19) between the ionization device (3) and the particle filter (10) for polarizing the particle filter (10).

3. The air cleaning method according to claim 2, It is characterized in that - the electrically conductive layer (14) is connected to the matching potential only until the polarization of the particle filter (10) reaches a predetermined polarization limit value or until a predetermined polarization time has expired, When the predetermined polarization limit value is reached or when the polarization time has expired, the electrically conductive layer (14) of the particle filter (10) is electrically separated from the matching potential (9).

4. The air cleaning method according to claim 3, It is characterized in that - the electrically conductive layer (14) is separated from the matching potential (9) only until the polarization of the particle filter (10) reaches a predetermined depolarization limit value or until a predetermined depolarization time has expired, When the predetermined depolarization limit value is reached or when the depolarization time has expired, the electrically conductive layer (14) of the particle filter (10) is electrically connected again to the matching potential (9).

5. The air cleaning method according to any one of claims 1 to 4, It is characterized in that - the corona induction electrode (6) is negatively polarized, while the matching electrode (7) and the matching potential (9) are positively polarized, or - the corona induction electrode (6) is positively polarized, while the matching electrode (7) and the matching potential (9) are negatively polarized, and / or The matching electrode (7) is electrically connected to the matching potential (9), wherein the conductive layer (14) of the particle filter (10) is electrically connected to the matching electrode (7) so that the conductive layer (14) is electrically connected to the matching potential (9).

6. A heating, ventilation and air conditioning system (HVAC system) (1) for a motor vehicle (2), the heating, ventilation and air conditioning system having: - an ionization device (3) for generating a corona discharge field (4), the ionization device comprising at least one corona induction electrode (6) of an electrical polarity and at least one counter electrode (7) of an electrical polarity opposite to the corona induction electrode (6), - a particle filter (10) for removing particles from the air flow (28), an air path (12) which specifies a flow direction (11) of the air towards the vehicle interior (29) and which guides the air through the ionization device (3) and the particle filter (10), - in, The ionization device (3) is arranged upstream of the particle filter (10) in the air path (12), It is characterized in that - the respective corona induction electrode (6) has a plurality of needles (20) which are oriented in the direction of flow (11) of the air or against the direction of flow (11) of the air, The respective corona induction electrode (6) and the associated counter electrode (7) are spaced apart from one another transversely to the flow direction (11) of the air.

7. The HVAC system (1) according to claim 6, It is characterized in that The respective corona induction electrode (6) has a plurality of inflow-side needles (22) which point away from the particle filter (10), so that the tips (24) of the inflow-side needles (22) face away from the particle filter (10).

8. The HVAC system (1) according to claim 6 or 7, It is characterized in that The respective corona induction electrode (6) has a plurality of outflow-side needles (21) which are aligned with the particle filter (10) so that the tips (24) of the outflow-side needles (21) face the particle filter (10).

9. The HVAC system (1) according to any one of claims 6 to 8, It is characterized in that - the respective counter electrode (7) is designed, in particular, as a flat plate which extends parallel to the respective corona induction electrode (6) and / or The respective corona induction electrode ( 6 ) and the associated counter electrode ( 7 ) each extend straight and preferably transversely to the flow direction ( 11 ) of the air.

10. The HVAC system (1) according to any one of claims 6 to 9, It is characterized in that The electrical connection (15) is designed to be switchable, so that the respective conductive layer (14) can be connected to the matching potential (9) or disconnected from it as required.

11. The HVAC system (1) according to any one of claims 6 to 10, It is characterized in that The HVAC system (1) has a control device (17) which is configured to carry out the air cleaning method according to any one of claims 1 to 5.

12. The HVAC system (1) according to any one of claims 6 to 11, It is characterized in that - the particle filter (10) is configured as a multilayer and has at least one dielectric layer (13) and at least one electrically conductive layer (14), The HVAC system (1) has an electrical connection (15) for electrically connecting the respective conductive layer (14) to a matching potential (9) which is of opposite electrical polarity with respect to the corona induction electrode (6).

13. The HVAC system (1) according to any one of claims 6 to 12, It is characterized in that The dielectric layer (13) of the particle filter (10) is designed as a particle filter layer (25) having a nonwoven fabric or consisting of a nonwoven fabric.

14. The HVAC system (1) according to any one of claims 6 to 13, It is characterized in that - the electrically conductive layer (14) of the particle filter (10) is designed as an adsorptive filter layer (26) having activated carbon particles or consisting of activated carbon particles, or The electrically conductive layer (14) of the particle filter (10) is designed as a grid structure (27) which comprises or consists of electrically conductive wires, electrically conductive fibers or electrically conductive threads.

15. The HVAC system (1) according to any one of claims 6 to 14, It is characterized in that - A respective dielectric layer (13) is disposed on said conductive layer (14) and is in contact therewith.

16. The HVAC system (1) according to any one of claims 6 to 15, It is characterized in that - In the particle filter (10), the respective dielectric layer (13) is arranged upstream of the respective conductive layer (14).

17. The HVAC system (1) according to any one of claims 6 to 16, It is characterized in that - the inlet-side needles (22) are at a predetermined distance (31) from each other on the inlet side (30) of the needle holder (23), and / or - the outflow-side needles (21) are at a predetermined distance (33) from each other on the outflow side (32) of the needle holder (23), and / or - the distance (31) between the needles (22) on the inlet side is the same as the distance (33) between the needles (21) on the outlet side, and / or At least one outflow-side needle (21) is arranged approximately centrally between two adjacent inflow-side needles (22).

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