Air purification process and heating, ventilation and air conditioning system

Abstract

The invention relates to a heating, ventilation and air conditioning system (HVAC system) (1) for a motor vehicle (2), comprising an ionization device (3) for generating a corona discharge field (4) which has at least one electrically polarized spray electrode (6) and at least one oppositely polarized counter electrode (7), a particle filter (10) for removing particles from an airflow (28), and an air path (12) which defines a flow direction (11) for air leading to a vehicle interior (29) and which guides the air through the ionization device (3) and through the particle filter (10), wherein the ionization device (3) is arranged upstream of the particle filter (10) in the air path (12). An extended service life for the particulate filter (10) can be achieved if the particulate filter (10) is configured in multiple layers and has at least one dielectric layer (13) and at least one electrically conductive layer (14), and if the HVAC system (1) has an electrical connection (15) for electrically connecting the respective electrically conductive layer (14) to an electrical counter-potential (9) that is electrically polarized opposite to the respective spray electrode.

Description

[0001] The present invention relates to an air purification method for a heating, ventilation, and air conditioning system of 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.

[0002] A heating, ventilation and air conditioning system is often referred to as an HVAC system, where HVAC stands for Heating, Ventilation and Air Conditioning.

[0003] A generic 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 electrically polarized discharge electrode and at least one counterelectrode electrically polarized opposite to the discharge electrode. The HVAC system further comprises a particle filter for removing particles from an air stream. Finally, the HVAC system has an air path that defines a flow direction for air leading to a vehicle interior and that guides the air through the ionization device and through the particle filter. The ionization device is arranged upstream of the particle filter in the air path. In the known HVAC system, the counterelectrode is cylindrical, and the discharge electrode is arranged concentrically to the cylindrical counterelectrode and aligned parallel to its longitudinal center axis.

[0004] Other HVAC systems with ionization are known from EP 3 488 933 A1, from KR 10-2205159 B1, from US 2021 / 0 021 107 A1, from WO 2020 / 263171 A1 and from WO 2021 / 226639 A2.

[0005] Such HVAC systems are primarily used when there is comparatively little installation space available for the particulate filter, while at the same time a high filtration efficiency with a high air volume requirement for a longer period of time is desired. A high filtration efficiency can be achieved by a correspondingly small pore size within the particulate filter. However, as the pore size decreases, the flow resistance of the particulate filter increases. To compensate for this, the flow-through surface of the particulate filter can be increased accordingly. However, the increase in the filter surface is limited by the available installation space. Particularly in areas with high particulate matter pollution, a particulate filter with a sufficiently small pore size can only meet the desired air volume requirement or air flow requirement for a short time.The filtration effect cannot be achieved because the increasing load causes it to quickly become clogged and the flow resistance rises to unacceptably high levels. With the help of particle filters, which are electrostatically charged during production, fine particles can be filtered out of the air stream, even with larger pores, if these particles are first ionized. Due to electrostatic attraction, the particles adhere to the charged filter material. The ionization of particles can also increase the efficiency of particle collection. The ionization of the particles is carried out using an ionization device. An electrostatic field is generated between a spray electrode and a counter electrode, which is referred to as a corona discharge field. The spray electrode is preferably negatively polarized, while the counter electrode is positively polarized or grounded.The corona discharge is generated at the sharp tips of the negatively polarized discharge electrodes, resulting in a large number of high-speed electrodes moving toward the opposite electrode. When these electrons collide with gas molecules in the air stream, either further electrons are split off or the electrons attach themselves to the gas molecules. In the first case, new free electrons and positive gas ions are created; in the second case, negative gas ions are formed. In principle, this gas ionization also works with reversed polarity, i.e., with a positively polarized discharge electrode and a negatively polarized counter electrode.

[0006] Particle charging occurs via the gas ions and begins when the particles enter the corona discharge chamber through which the spray stream flows. The particles are charged by the attachment of gas ions to the particles when they collide with the particles. The charging process occurs through field and diffusion charging.

[0007] However, it has been shown that the original electrostatic charge of the particulate filter, which was originally provided by the manufacturer, diminishes as a result of the particulate load, so that the filtration efficiency of the particulate filter diminishes significantly after even a short period of inactivity. To compensate for this, particulate filter replacement intervals can be significantly shortened, although this is associated with correspondingly high costs.

[0008] The present invention addresses the problem of providing an improved or at least a different embodiment for an HVAC system of the type described above or for an air purification method, which is characterized in particular by a high filtration effect at high air volumes during a long service life.

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

[0010] The air purification method according to the invention for an HVAC system of a motor vehicle is based on the general idea of ​​equipping the particulate filter with at least one electrically conductive layer that is set to an electrical potential polarized opposite to the discharge electrode, so that an electric field is generated between the ionization device and the particulate filter during operation of the ionization device. The electric field between the ionization device and the particulate filter can polarize the particulate filter. This electric field can therefore also be referred to as a polarization field. The achieved polarization of the particulate filter essentially regenerates the electrostatic charge of the particulate filter. This allows a virtually consistently high filtration efficiency to be achieved over the intended service life or lifetime of the particulate filter, even for large air volumes.The respective potential can be provided on the electrically conductive layer of the particle filter by electrically contacting or electrically connecting the electrically conductive layer with an electrical counterpotential that is electrically polarized opposite to the spray electrode.

[0011] According to an advantageous embodiment, it can be provided that the conductive layer is only connected to the counterpotential until the electrostatic charge of the particulate filter reaches a predetermined regeneration limit. Upon reaching the predetermined regeneration limit, the respective electrically conductive layer of the particulate filter is electrically separated from the counterpotential. Additionally or alternatively, in another embodiment, it can be provided that the conductive layer is only connected to the counterpotential until a predetermined regeneration time has elapsed. Upon expiration of the predetermined regeneration time, the respective electrically conductive layer of the particulate filter is electrically separated from the counterpotential. In this case, the time is thus monitored. Monitoring of the electrostatic regeneration is not necessary for this.These measures are based on the finding that after successful polarization of the particulate filter, the resulting electrostatic charge is only slowly dissipated or discharged during operation of the HVAC system, namely by the particles filtered out of the airflow. Thus, the particulate filter regenerated by polarization behaves essentially like a new particulate filter that was electrostatically charged during its manufacture. The separation from the mass means that the electric field between the ionization device and the particulate filter no longer needs to be created and maintained, which means the ionization device requires less electrical power. This allows the HVAC system to operate more efficiently.

[0012] While generating the electric field to polarize the particulate filter, the ionization device operates at a comparatively high electrical power. With increased electrical power, more ozone is generated in the airflow. As the respective electrically conductive layer is separated from the counterpotential, the electrical power of the ionization device decreases, resulting in less ozone being generated, which is beneficial for reducing ozone pollution in the vehicle interior.

[0013] According to an advantageous development of the air purification method, it can be provided that the conductive layer is only separated from the counterpotential until the polarization of the particulate filter reaches a predetermined depolarization threshold. In other words, the electrostatic charge of the particulate filter is monitored. If this falls below the depolarization threshold, the filter polarization is performed to refresh the electrostatic charge. This refreshing or polarization can be repeated virtually any number of times. When the predetermined depolarization threshold is reached, the electrically conductive layer of the particulate filter is electrically reconnected to the counterpotential. Subsequently, the particulate filter is polarized or electrostatically recharged again.Additionally or alternatively, another embodiment may provide for the conductive layer to be separated from the counterpotential only until a predetermined depolarization time has elapsed. After the depolarization time has elapsed, the electrically conductive layer of the particle filter is electrically reconnected to the counterpotential. In this case, the time is thus monitored. Monitoring the polarization is not required for this purpose.

[0014] The regeneration time and / or the depolarization time depend on the application intended for the respective particulate filter, whereby in particular conditions such as the dimensioning of the particulate filter, the filtration effect and / or air volume to be achieved and the particulate matter load at the respective location where the particulate filter is used can be taken into account.

[0015] In principle, an embodiment in which the spray electrode is positively polarized, while the counter electrode and the counter potential are negatively polarized, can be advantageous. However, an embodiment in which the spray electrode is negatively polarized, while the counter electrode and the counter potential are positively polarized, is preferred. Ionization is particularly efficient in this case.

[0016] According to an advantageous embodiment, it can be provided that the counter electrode is electrically connected to the counter potential, in particular permanently, and that the electrically conductive layer of the particulate filter is electrically connected to the counter electrode in order to electrically connect the electrically conductive layer to the counter potential. This configuration can be implemented particularly easily.

[0017] The HVAC system according to the invention is based on the general idea of ​​providing at least one electrically conductive layer in the particulate filter and configuring it such that it can be electrically connected to an electrical counterpotential that is electrically polarized opposite to the discharge electrode. For this purpose, the HVAC system is equipped with an electrical connection configured such that this electrical connection can electrically connect or contact the respective electrically conductive layer with the electrical counterpotential. In the simplest case, this can be achieved using a ground cable that is electrically connected to the ground of the ionization device.

[0018] In the present context, a ‘configuration’ is synonymous with a ‘design’ and / or ‘programming’, so that the phrase ‘configured so that’ is synonymous with the phrase ‘designed and / or programmed so that’.

[0019] An embodiment in which the electrical connection is switchable is advantageous. This allows the respective electrically conductive layer to be connected to and separated from the counterpotential as required. During operation of the ionization device, the particle filter can be polarized when the electrically conductive layer is electrically connected to the counterpotential in order to regenerate its electrostatic charge. If the electrostatic charge is sufficient, further polarization can be stopped by breaking the connection to the counterpotential in order to save electrical energy and reduce the production of ozone. The switchability of the connection can be realized, for example, by means of an electromechanical or electronic switch.

[0020] A particularly advantageous embodiment is one in which the HVAC system has a control device configured to carry out the air purification process described above 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, to carry out the air purification process described above.

[0021] According to an advantageous embodiment, the spray electrode can have a plurality of needles aligned in or against the direction of air flow. These needles protrude from a needle carrier in or against the direction of air flow. The needles can extend at an angle or parallel to the direction of air flow. The respective spray electrode and the associated counter electrode are arranged in the air path at a distance from one another, transverse to the direction of air flow.

[0022] According to an advantageous embodiment, the respective spray electrode can have a plurality of downstream needles extending in the flow direction and aligned with the particulate filter. In the downstream needles aligned with the particulate filter, the tips of these needles face the particulate filter.

[0023] In another advantageous embodiment, the respective spray electrode can have a plurality of upstream needles that extend counter to the flow direction and are directed away from the particulate filter. Consequently, the tips of these needles face away from the particulate filter. Although an embodiment is preferred in which the respective spray electrode has the upstream needles and the downstream needles, embodiments in which the upstream needles or the downstream needles are omitted are also possible.

[0024] According to an advantageous embodiment, the respective counterelectrode can be designed as a plate, preferably as a flat plate. The plate-shaped counterelectrode can extend parallel to the respective spray electrode. The respective plate is flat, i.e. has a plate thickness that is small compared to a plate length and a plate width. For example, the respective plate is arranged in the air flow such that the plate width extends parallel to the direction of air flow, while the plate length and the plate thickness each extend transversely to the direction of air flow. Thus, only a narrow edge of the plate-shaped counterelectrode is exposed to the air flow. Additionally or alternatively, it can be provided that the respective spray electrode and the associated counterelectrode each extend in a straight line and preferably transversely to the direction of air flow.This design allows for the generation of a particularly efficient corona discharge field, achieving particularly effective ionization of the particles entrained in the air stream. Furthermore, this configuration is comparatively small relative to the direction of air flow.

[0025] The dielectric layer of the particulate filter can be designed as a particle filter layer that includes or consists of a nonwoven fabric. Nonwoven fabrics are typically made of plastic and are therefore dielectric. Nonwoven fabrics can, in particular, be manufactured as so-called blow-melt fabrics. The particle filter layer defines the pore size of the particulate filter and is impermeable to particles whose grain size is larger than the pore size.

[0026] In another embodiment, the electrically conductive layer of the particulate filter can be configured as an adsorption filter layer comprising or consisting of activated carbon particles. Due to the electrically conductive activated carbon particles adhering to one another, the adsorption filter layer is electrically conductive as a whole and, through its grounding, can be used to generate the electric polarization field. The adsorption filter layer filters by adsorption, with the adsorption filter layer having an adsorbent effect, particularly for gas molecules. The activated carbon particles can adhere to a nonwoven layer or be held between two nonwoven layers.

[0027] Alternatively, the electrically conductive layer of the particulate filter can be designed as a grid structure that includes or consists of electrically conductive wires, fibers, or threads. Unlike a particulate filter layer or an adsorption filter layer, the grid structure has no significant filtration effect.

[0028] A suitable embodiment is one in which the respective dielectric layer rests on the electrically conductive layer and is in contact with it. In particular, the electrically conductive layer extends over the entire extent of the respective dielectric layer. This measure allows the electric field generated by grounding the electrically conductive layer to also extend to the dielectric layer, so that, in particular, the dielectric layer can be polarized or electrostatically charged.

[0029] A configuration in which the respective dielectric layer is arranged upstream of the respective electrically conductive layer in the particulate filter has proven particularly advantageous. This results in electrons and / or ions transported in the electric field colliding with the dielectric layer on their way to the electrically conductive layer, adhering there and causing the desired polarization.

[0030] Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures based on the drawings.

[0031] It is understood that the features mentioned above and those to be explained below can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention as defined by the claims. Components mentioned above and those to be mentioned below of a higher-level unit, such as a device, apparatus, or arrangement, which are designated separately, may form separate parts or components of this unit or be integral areas or sections of this unit, even if this is shown differently in the drawings.

[0032] Preferred embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components.

[0033] They show, schematically, Fig. 1 a simplified, circuit diagram-like schematic diagram of an HVAC system with particle filter and ionization device, Fig. 2 a simplified cross-section through the particle filter according to section lines II in Fig. 1, Fig. 3 a simplified cross-section through the ionization device according to section lines III in Fig. 1 in the area of ​​a pair of electrodes at different states a and b, Fig. 4 a simplified side view of the electrode pair Fig. 3 corresponding to a viewing direction IV in Fig. 3.

[0034] Accordingly Fig. 1, an HVAC system 1 of a motor vehicle 2, which is only partially shown here, comprises an ionization device 3, with the aid of which an Fig. 3 by broken lines can be generated. For this purpose, the ionization device 3 has at least one pair of electrodes 5, which has a negatively or positively electrically polarized discharge electrode 6 and a counter electrode 7 with opposite electrical polarity. In the example of Fig. 1, four such electrode pairs 5 are shown. It is clear that in another embodiment, more than two, in particular three or more such electrode pairs 5 can be used. In particular, n spray electrodes 6 and n+1 counter electrodes 7 can be provided in the ionization device 3, so that each spray electrode 6 is arranged transversely to the flow direction 11 between two counter electrodes 7. In Fig. 3, only one counter electrode 7 is shown for simplified representation.

[0035] The respective spray electrode 6, which can also be referred to as emitter electrode, is suitably connected to a high-voltage source 8, which provides, for example, a direct voltage in the range of 5 kV to 10 kV, preferably of approximately 7 kV. The counter electrodes 7 are suitably electrically connected to a counter potential 9 that is electrically opposite to the spray electrode 7. In the preferred case shown here, the respective spray electrodes 6 are negatively polarized and the associated counter electrodes 7 are positively polarized. Accordingly, the counter potential 9 is also positively polarized, which in the Fig. 1 and Fig. 2 is simplified by a mass symbol.

[0036] The HVAC system 1 also includes a particle filter 10 configured to remove particles from an air flow 28, indicated in the figures by wavy arrows. During operation of the HVAC system 1, the air flow 28 has a flow direction 11, indicated in the figures by arrows. An air path 12 is formed in the HVAC system 1, which Fig. 1 to 4 is indicated by a dash-dotted line. The air path 12 defines the flow direction 11 for the air. The air path 12 leads through the ionization device 3 and through the particulate filter 10. It is noteworthy that the ionization device 3 is arranged upstream of the particulate filter 10 in the air path 12 with respect to the air flow direction 11. The air path 12 guides the air to a vehicle interior 29 of the vehicle 2 (not shown in detail). The air can be fresh air from the surroundings of the vehicle 2 or recirculated air from the vehicle interior 29 or a mixture of fresh air and recirculated air.

[0037] According to the Fig. 1 and Fig. 2, the particulate filter 10 is configured in a multi-layered manner, such that it has at least one dielectric layer 13 and at least one electrically conductive layer 14. The HVAC system 1 is also equipped with an electrical connection 15, which serves to electrically connect the respective electrically conductive layer 14 to the counter potential 9. The electrical connection 15 can be configured according to Fig. 1 can be designed to be switchable according to an advantageous embodiment. For example, the connection 15 can contain a switch 16 with which the electrical contact between the electrically conductive layer 14 and the counter potential 9 can be opened and closed as needed. In the example of Fig. 1, the electrically conductive layer 14 can be electrically connected to the respective counter electrode 7 and to the counter potential 9 via the connection 15 and the switch 16.

[0038] According to Fig. 1, the HVAC system 1 can also be equipped with a control device 17, which can be connected in a suitable manner, for example via control lines 18, to the high-voltage source 8 and to the switch 16. The control device 17 can be configured to carry out an air purification method described in more detail below.

[0039] According to the air purification process, an air stream 28 contaminated with particles is guided along the air path 12, first through the ionization device 3 and then through the multi-layer particle filter 10. In doing so, the ionization device 3 generates the corona discharge field 4 by means of the respective spray electrode 6 and the associated counter electrode 7. The air stream 28 to be purified is guided through the corona discharge field 4. The particles entrained in the air stream 28 are ionized in the corona discharge field 4. For the air purification process, the electrically conductive layer 14 is also electrically connected or contacted to the counter potential 9 by the electrical connection 15, so that an electrical field 19 is generated between the ionization device 3 and the particle filter 10, which Fig. 3 and Fig. 4 is indicated by dashed lines and is hereinafter referred to as polarization field 19. This polarization field 19 enables polarization of the particle filter 10, which ultimately leads to an electrostatic charging of the particle filter 10.

[0040] The air purification process can be expediently configured such that the conductive layer 14 is connected to the counterpotential 9 only until the polarization of the particulate filter 10 reaches a predetermined regeneration threshold and / or until a predetermined regeneration time has elapsed. Upon reaching this predetermined regeneration threshold or upon expiration of the predetermined regeneration time, the electrically conductive layer 14 of the particulate filter 10 is electrically separated from the counterpotential 9. This can be done by opening the switch 16. During filtration operation, the electrostatic charge of the particulate filter 10 decreases again.In addition, the air purification method can be configured such that the conductive layer 14 is only separated from the counterpotential 9 until the polarization of the particle filter 10, i.e. its electrostatic charge, reaches a predetermined depolarization limit and / or until a predetermined depolarization time has elapsed. Upon reaching the predetermined depolarization limit or upon expiration of the depolarization time, the electrically conductive layer 14 of the particle filter 10 is electrically connected again to the counterpotential 9. This can be done, for example, by closing the switch 16. In particular, it can be provided that the initial electrical connection of the electrically conductive layer 14 to the counterpotential 9 only occurs when the electrostatic charge of the particle filter 10 reaches the predetermined depolarization limit and / or when the predetermined depolarization time has elapsed.

[0041] According to the Fig. 1, Fig. 3 and Fig. 4, the respective spray electrode 6 can have a plurality of needles 20 which protrude from a needle carrier 23 and have at their end remote from the needle carrier 23 a needle tip 24 or tip 24 which only in the Fig. 3 and Fig. 4 are described in more detail. In the respective electrode pair 5, the spray electrode 6 and the counter electrode 7 are spaced apart from one another transversely to the flow direction 11, so that the air path 12 can guide the air flow 28 between the spray electrode 6 and the counter electrode 7. If several electrode pairs 5 are adjacent transversely to the flow direction 11, the spray electrodes 6 can be arranged between two counter electrodes 7 and interact with both counter electrodes 7 to form the corona discharge field 4.

[0042] The needles 20 of the respective spray electrode 6 can be moved according to Fig. 3 and Fig. 4 extend parallel to the flow direction 11. They thus protrude from the needle carrier 23 in or against the flow direction 11. The needles 20 are in the Fig. 1 and Fig. 3 pin-shaped. In Fig. 4, they are conical or pyramid-shaped. Plate-shaped needles 20 are also conceivable, tapering to form the needle tip 24.

[0043] According to the Fig. 1, Fig. 3 and Fig. 4, the respective spray electrode 6 can have a plurality of downstream needles 21 aligned with the particulate filter 10. In other words, the downstream needles 21 protrude from the needle carrier 23 toward the particulate filter 10. Consequently, the tips 24 of the downstream needles 21 face the particulate filter 10. Preferably, the downstream needles 21 extend parallel to the air flow direction 11.

[0044] In addition to or alternatively to the downstream needles 21, the respective spray electrode 6 can have a plurality of upstream needles 22 directed away from the particle filter 10. In other words, the upstream needles 22 protrude from the needle carrier 23, directed away from the particle filter 10. The tips 24 of these upstream needles 22 then also face away from the particle filter 10. The upstream needles 22 can expediently extend parallel to the air flow direction 11. The upstream needles 22 serve primarily to generate the corona discharge field 4.

[0045] When the high voltage potential is applied to the spray electrodes 6 and according to Fig. 3a, the switch 16 is turned off, the electric corona discharge field 4 is formed between the spray electrodes 6 and the counter electrodes 7, namely between the tips 24 of the needles 21 and 22 and the counter electrodes 7. This electric field, i.e. the corona discharge field 4, is mainly responsible for the electrostatic charging of the particles in the air stream 28. If, on the other hand, the high voltage potential is applied to the spray electrode 6 and according to Fig. 3b, the switch 16 is turned on and connected to the counter electrode 9, the electric corona discharge field 4 is formed primarily between the spray electrodes 6 and the counter electrodes 7, namely between the tips 24 of the needles 21 and 22 and the counter electrodes 7, with an additional electric field 19 being formed between the tips 24 of the downstream needles 21 and the filter element 10, primarily the filter element layer 14. Here, the electric field 19 is used primarily for the polarization or regeneration of the layer 13 of the filter element 10. The intensity of the electric field 19 is strong when the switch 16 is turned on, and the electric field intensity of the field 19 is low when the switch 16 is turned off.

[0046] The spray electrodes 6 can be held on dielectric high-voltage insulators which are part of a Fig. 1 indicated housing 30 of the HVAC system 1 or are separate units arranged in the housing 30 of the HVAC system 1. These insulators are in the Fig. 1 to 4 are not shown. Various shapes and different dielectric materials can be used to manufacture the high-voltage insulators. The high-voltage insulators serve to electrically insulate the discharge electrodes 6 from the counter electrodes 7, which have an opposite potential or are grounded, or from a grounded housing 30 of the HVAC system 1, or from grounded vehicle components, or from the grounded vehicle 2.

[0047] The respective counterelectrode 7 can expediently be designed as a plate that extends parallel to the respective spray electrode 6. The respective counterelectrode 7 can be flat, i.e., as a flat plate. The spray electrode 6 and the counterelectrode 7 can extend linearly and parallel to each other and, in particular, perpendicular to the air flow direction 11. For example, the respective needle carrier 23 is configured as a linear rod. According to Fig. 1, the counterelectrodes 7, designed as flat plates, extend parallel to each other and in planes that run parallel to the flow direction 11 of the air stream 28. Thus, the counterelectrodes 7 are spaced apart from each other transversely to the flow direction 11.

[0048] According to Fig. 2, the dielectric layer 13 of the particulate filter 10 can be configured as a particulate filter layer 25 formed with at least one nonwoven fabric. In contrast, the electrically conductive layer 14 of the particulate filter 10 can be configured as an adsorption filter layer 26 comprising activated carbon particles. In addition to or as an alternative to such an adsorption filter layer 26, it can also be provided that the electrically conductive layer 14 of the particulate filter 10 is configured as a lattice structure 27 formed using electrically conductive wires, fibers, or threads.

[0049] The electrically conductive layer 14 lies within the particle filter 10 on the dielectric layer 13 and is in contact therewith. Preferably, the contact is as large as possible. In particular, the electrically conductive layer 14 can extend over the entire downstream or upstream surface of the dielectric layer 13. In the example of Fig. 2, the particulate filter 10 is folded, with the electrically conductive layer 14 following the folds of the dielectric layer 13 and also being folded. The configuration shown here is preferred, in which the respective dielectric layer 13 is arranged upstream of the respective electrically conductive layer 14 within the particulate filter 10. However, an embodiment is also conceivable in which the respective dielectric layer 13 is arranged downstream of the respective electrically conductive layer 14 within the particulate filter 10.

[0050] It is clear that the HVAC system 1 may also include a heater for heating the air flow 28 and a cooler for cooling and drying the air flow 28. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] EP 3 056 364 B1

[0003] EP 3 488 933 A1

[0004] KR 10-2205159 B1

[0004] US 2021 / 0 021 107 A1

[0004] WO 2020 / 263171 A1

[0004] WO 2021 / 226639 A2

[0004]

Claims

[1] Air purification process for a heating, ventilation and air conditioning (HVAC) system (1) of a motor vehicle (2), - in which an air stream (28) contaminated with particles first flows through an ionisation device (3) and then through a multi-layer particle filter (10), the particle filter (10) having at least one dielectric layer (13) and at least one electrically conductive layer (14), - in which the ionisation device (3) generates a corona discharge field (4) by means of at least one electrically polarised spray electrode (6) and at least one counter-electrode (7) which is electrically polarised opposite to the spray electrode, - in which the air stream (28) to be cleaned is guided through the corona discharge field (4) so ​​that the particles carried along are ionised, - in which the electrically conductive layer (14) of the particle filter (10) is electrically connected to a counter-potential (9) which is electrically polarized opposite to the spray 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). [2] Air purification method according to claim 1, characterized by , - that the conductive layer (14) is only connected to the counter potential until the polarization of the particle filter (10) reaches a predetermined regeneration limit value or until a predetermined regeneration time has elapsed, - that when the predetermined regeneration limit value is reached or when the regeneration time has elapsed, the electrically conductive layer (14) of the particle filter (10) is electrically separated from the counter potential (9). [3] Air purification method according to claim 2, characterized by , - that the conductive layer (14) is separated from the counter potential (9) only until the polarization of the particle filter (10) reaches a predetermined depolarization limit value or until a predetermined depolarization time has elapsed, - that when the predetermined depolarization limit value is reached or when the depolarization time has elapsed, the electrically conductive layer (14) of the particle filter (10) is electrically connected again to the counter potential (9). [4] Air purification method according to one of claims 1 to 3, characterized by , - that the spray electrode (6) is negatively polarized, while the counter electrode (7) and the counter potential (9) are positively polarized. [5] Air purification method according to one of claims 1 to 4, characterized by , - that the counter electrode (7) is electrically connected to the counter potential (9), - that the electrically conductive layer (14) of the particle filter (10) is electrically connected to the counter electrode (7) in order to electrically connect the electrically conductive layer (14) to the counter potential (9). [6] Heating, ventilation and air conditioning system (HVAC system) (1) for a motor vehicle (2), - with an ionization device (3) for generating a corona discharge field (4), which has at least one electrically polarized spray electrode (6) and at least one counter electrode (7) electrically polarized opposite to the spray electrode (6), - with a particle filter (10) for removing particles from an air stream (28), - with an air path (12) which defines a flow direction (11) for air leading to a vehicle interior (29) and which guides the air through the ionisation device (3) and through the particle filter (10), - wherein the ionization device (3) is arranged upstream of the particle filter (10) in the air path (12), characterized by , - that the particle filter (10) is configured in multiple layers and has at least one dielectric layer (13) and at least one electrically conductive layer (14), - that the HVAC system (1) has an electrical connection (15) for electrically connecting the respective electrically conductive layer (14) to an electrical counter potential (9) which is electrically polarized opposite to the spray electrode (7). [7] HVAC system (1) according to claim 6, characterized by , - that the electrical connection (15) is designed to be switchable, so that the respective electrically conductive layer (14) can be connected to and separated from the counter potential (9) as required. [8] HVAC system (1) according to claim 6 or 7, characterized by , - that the HVAC system (1) comprises a control device (17) configured to carry out the air purification method according to one of claims 1 to 5. [9] HVAC system (1) according to one of claims 6 to 8, characterized by , - that the respective spray electrode (6) has a plurality of needles (20) which are aligned in the flow direction (11) of the air or opposite to the flow direction (11) of the air, - that the respective spray electrode (7) and the associated counter electrode (7) are spaced apart from each other transversely to the flow direction (11) of the air. [10] HVAC system (1) according to claim 9, characterized by , - that the respective spray electrode (6) has a plurality of downstream needles (21) which are aligned with the particle filter (10) so that tips (24) of the downstream needles (21) face the particle filter (10). [11] HVAC system (1) according to claim 9 or 10, characterized by , - that the respective spray electrode (6) has a plurality of upstream needles (22) which are directed away from the particle filter (10), so that tips (24) of the upstream needles (22) are directed away from the particle filter (10). [12] HVAC system (1) according to one of claims 6 to 11, characterized by , - that the respective counter electrode (7) is designed as a, in particular flat, plate which extends parallel to the respective spray electrode (6), and / or - that the respective spray electrode (6) and the associated counter electrode (7) each extend in a straight line and preferably transversely to the flow direction (11) of the air. [13] HVAC system (1) according to one of claims 6 to 12, characterized by , - that the dielectric layer (13) of the particle filter (10) is designed as a particle filter layer (25) which has or consists of a fiber fleece. [14] HVAC system (1) according to one of claims 6 to 13, characterized by , - that the electrically conductive layer (14) of the particle filter (10) is designed as an adsorption filter layer (26) which comprises or consists of activated carbon particles. [15] HVAC system (1) according to one of claims 6 to 13, characterized by , - that the electrically conductive layer (14) of the particle filter (10) is designed as a lattice structure (27) which has or consists of electrically conductive wires or electrically conductive fibers or electrically conductive threads. [16] HVAC system (1) according to one of claims 6 to 15, characterized by , - that the respective dielectric layer (13) rests on the electrically conductive layer (14) and is in contact therewith. [17] HVAC system (1) according to one of claims 6 to 16, characterized by , - that in the particle filter (10) the respective dielectric layer (13) is arranged upstream of the respective electrically conductive layer (14).

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