AIR PURIFICATION DEVICE AND AIR PURIFICATION SYSTEM AND METHOD FOR CLEANING AN AIR PURIFICATION DEVICE AND AN AIR PURIFICATION SYSTEM

Description

TECHNICAL FIELD

[0001] The present invention relates to an air purification device according to the preamble of patent claim 1. It further relates to an air purification system for at least one substantially enclosed space, in particular an interior of a vehicle cabin such as the passenger compartment of an aircraft, comprising such an air purification device. However, the air purification device according to the invention is not limited to use in an aircraft air purification system, but can be implemented in all air purification systems for stationary or mobile spaces in which people and / or animals are temporarily present. Furthermore, the invention relates to a method for cleaning an air purification device and an air purification system for at least one substantially enclosed space. BACKGROUND OF THE INVENTION

[0002] Air purification systems for enclosed spaces are often installed decentrally outside the rooms, for example, integrated into room-integrated or building-integrated heating and / or air conditioning systems. The air in the room is circulated through the air purification system located outside the room. The air from the room is guided through an exhaust duct arrangement to the air purification system. There, coarse dirt and dust particles are typically first removed from the air by mechanical pre-filters. Biological pollutants such as viruses, bacteria, and / or fungal spores are then killed or biologically deactivated in an electrostatic precipitator module, which may have an ionizer, for example.The air is then passed through another mechanical filter device, which may contain, for example, mechanical fine filters such as HEPA filters and / or harmful gas filters (e.g., activated carbon filters or molecular sieve filters) to remove chemical pollutants from the air. The cleaned air is then recirculated through a clean air duct system into the room. Both in such an air purification device and in similar air purification systems, deposits and accumulations of biological air pollutants can occur in the exhaust air duct system between the room and the air purification device. These contaminants are already separated upstream of the air purification device and are not captured by the air purification system. The resulting biological contamination of the air purification device and the exhaust air duct system can lead to "backward contamination" of the room over an extended period. STATE OF THE ART

[0003] German patent application DE 10 2020 121 872 A1 describes a generic air purification system that, for example, purifies the air in a passenger cabin of an aircraft. To deactivate biological air pollutants, it provides an electrostatic precipitator module through which the air to be purified flows. The electrostatic precipitator module has at least one high-voltage electrode and at least one control electrode, between which an electric field can be generated by applying a high voltage provided by a power supply module.

[0004] The structure and mode of operation of an electrostatic precipitator module designed as an ionization module are described in detail, for example, in US Pat. No. 6,413,301 B1 and WO 02 / 16042 A2. The present applicant's German patent application DE 10 2020 122 848 A1 mentions that UVC light sources are provided inside an air duct panel element, which is part of an air duct system leading to an air purification device. These light sources can be used to disinfect the interior of the air duct panel element as needed and kill viruses, bacteria, and fungi that have accumulated there. However, this requires the provision of an additional lighting infrastructure for the UVC light sources.

[0005] JP 2002 - 103 959 A discloses an air purification device for building interiors, comprising a fan, an electrostatic filter, and an ozone generator. By reversing the fan direction, the drawn-in air can be directed through the air purification device in two opposite directions. The airflow direction can be reversed as needed, depending on whether the air is desired to be discharged near the floor or at head height. During times when no people are in the building or interior, the air can be enriched with highly concentrated ozone using the ozone generator to deodorize and sterilize the room.

[0006] JP 2003 - 106 600 A discloses an air purification device comprising an electrostatic dust filter capable of generating ozone, several heat exchangers, a blower, and an ion generator capable of generating ozone. The air to be treated is drawn in through an air inlet, flows through the electrostatic dust filter and the heat exchangers, and is directed past the ion generator to an air outlet. This air purification device can be operated in a cleaning mode in which the blower is operated in reverse, with the air being directed from the air outlet past the ionizer and / or through the electrostatic dust filter, where it is enriched with ozone, into the interior of the air purification device. The air purification device is intended to be cleaned in this way.

[0007] JP H08 243 432 A shows and describes an air purification device comprising, in a housing—in the order of air flow—a pre-filter, an ozone-generating ionizer, a dust-collecting electrode, and a catalyst for converting ozone into oxygen. The air to be purified is drawn by a fan from a room in which the air purification device is installed, through the above-described arrangement, and blown back into the room. Cleaning of the air purification device itself is not provided. PRESENTATION OF THE INVENTION

[0008] The object of the present invention is to improve a generic air purification device and a generic air purification system in such a way that biological decontamination of the air ducts leading to the air purification device is possible without major additional equipment expenditure, and to provide a corresponding method for cleaning such an air purification device and such an air purification system.

[0009] The part of the problem directed at the air purification device is solved by the air purification device with the features of patent claim 1.

[0010] An air purification device is provided with at least one electrostatic precipitator unit, at least one air filter module and at least one air conveying device for conveying air sucked in through at least one raw air inlet for air to be purified in a main flow direction through the electrostatic precipitator unit and through the at least one air filter module to at least one clean air outlet for purified air, wherein the air purification device is switchable between an air purification mode in which the air flows in the main flow direction and a system purification mode in which the air flows at least partially countercurrent to the main flow direction through the air purification device and exits the air purification device through the at least one raw air inlet, and wherein the electrostatic precipitator unit is or can be activated in the system purification mode to generate ozone in order to enrich the air flowing through the electrostatic precipitator unit with ozone.According to the invention, the air cleaning device is designed in such a way that air filter modules are not flowed through by the air in a direction opposite to their respective local main flow direction during system cleaning operation.

[0011] A "local main flow direction" is the direction of flow in an air filter module in which air flows through the air filter module during filtration operation, i.e., during regular air purification operation. "Air purification operation" is understood to be an operating state of the air purification device in which the air flows in a main flow direction from the raw air inlet through the electrostatic precipitator unit and through any other filter modules provided to the clean air outlet. "Reverse flow operation" is understood to be an operating state in which the air, at least in areas of the air purification device, flows against the main flow direction, i.e., at least partially in countercurrent, through the air purification device and exits it through the raw air inlet."System cleaning operation" is understood to mean an operating state in which the air flows through the air cleaning device in reverse flow mode and thereby flows - in the main flow direction or in counterflow - through the ozone-generating electrostatic precipitator unit. ADVANTAGES

[0012] The electrostatic precipitator unit, which has at least one high-voltage electrode and at least one control electrode, between which an electric field can be generated by applying a high voltage provided by a power supply module, forms an ionizer that generates a plasma, preferably a cold plasma, during operation, releasing ozone. This ozone release is typically kept to a minimum during regular air purification operation, in which the air flows through the air purification device in the main flow direction, to prevent ozone from entering a room occupied by people (or animals) and causing damage due to its highly reactive and harmful properties.

[0013] However, when the room is unoccupied (or unoccupied), reverse flow operation allows for system cleaning. This involves deliberately and deliberately directing ozone-enriched air from the electrostatic precipitator unit through the air purification system against the main flow direction. The ozone exerts its disinfecting effect there, killing or deactivating biological pollutants that have accumulated in the air purification system and, where applicable, in the room. Avoiding flow through individual or all air filter modules during system cleaning operation against their respective main flow direction ensures that no pollutants already accumulated in the respective air filter module are released through filter backwash.

[0014] Further preferred and advantageous design features of the air purification device according to the invention are the subject of subclaims 2 to 10.

[0015] Preferably, the air purification device is designed so that the air filter modules for particle or suspended matter separation are not flowed through by air against the local main flow direction during system purification operation. This specifically prevents filter backwashing of those air filter devices that retain particulate pollutants through screening or filtration during air purification operation, for example, by adsorbing them to a filter material. Consequently, such particulate filter loads are not released again during system purification operation.

[0016] Preferably, the air purification device is designed such that, during system cleaning operation, at least a portion of the air filter modules, i.e. at least one, is flowed through by the ozone-enriched air in the local main flow direction.

[0017] A particularly simple and cost-effective variant of the invention is characterized in that the air conveying direction of the air conveying device is reversible in order to implement the flow reversal operation. If the air conveying device is formed by a blower, for example, or if it has one, the propeller or the fan wheel of the blower can be switched to reverse rotation against the standard direction of rotation and operated against the main flow direction. In this case, the blower conveys air against the main flow direction, essentially through the raw air inlet, back into the room, albeit with a much lower volume flow and less efficiency, thus resulting in system cleaning operation. However, appropriate air ducts and suitable valve arrangements can also be provided, through which the air is guided back to the raw air inlet.

[0018] Particularly advantageous is an embodiment in which the electrostatic precipitator unit is designed such that it produces a smaller amount of ozone in a first operating state (in air cleaning mode) than in a second operating state (in system cleaning mode), wherein the electrostatic precipitator unit can be or is switched to the second operating state in the flow reversal operation of the air conveying device, i.e. in system cleaning mode.

[0019] In a preferred embodiment of the air purification device according to the invention, which can be combined with other embodiments, at least one filter unit with at least one filter for particle separation and / or with at least one filter for separating chemical air pollutants is advantageously provided downstream of the electrostatic precipitator unit in the main flow direction, and the flow path of the air from the electrostatic precipitator unit through this downstream filter unit to the clean air outlet can be blocked or is blocked in flow reversal mode, i.e. in system cleaning mode, for example by a valve arrangement. This ensures that the ozone-enriched air originating from the electrostatic precipitator module, in which the ozone is formed, does not flow through this filter unit, but only against the main flow direction, thus causing no damage to the downstream filter unit.This is particularly advantageous if the filter unit contains filters that can be damaged by the high oxidizing power of ozone, or if the filter unit has an activated carbon filter that would remove the ozone desired for cleaning purposes from the air. Therefore, during system cleaning mode, the ozone-enriched air preferably does not flow through filter units containing activated carbon filters.

[0020] In another preferred embodiment of the air purification device according to the invention, which can be combined with other embodiments, the air purification device is preferably provided with an auxiliary air inlet through which air can be supplied to the electrostatic precipitator unit during system cleaning operation. This auxiliary air inlet enables the electrostatic precipitator unit to draw in air, for example ambient air, for system cleaning operation from outside or past the downstream filter unit.

[0021] Preferably, the auxiliary air inlet is located downstream of the electrostatic precipitator unit in the main air flow direction. This ensures that air flows backward through the electrostatic precipitator unit during system cleaning operation. However, the auxiliary air inlet can also be located upstream of the electrostatic precipitator unit in the main air flow direction, so that air flows forward through the electrostatic precipitator unit even during system cleaning operation. However, a flow reversal device must be provided to redirect the air flowing through the electrostatic precipitator unit during system cleaning operation back to the raw air inlet and the exhaust air duct arrangement.

[0022] A further preferred embodiment of the air purification device according to the invention, which can be combined with other embodiments, is characterized in that a pre-filter module for particle separation is provided upstream of the electrostatic precipitator unit. This pre-filter module is equipped with a switchable bypass through which the ozone-enriched air can be directed past the pre-filter module during system cleaning operation to the at least one raw air inlet. In this variant, the bypass ensures that the air flowing from the electrostatic precipitator unit to the exhaust air duct arrangement does not flow backward through the mechanical pre-filter module. This prevents backwashing of the pre-filter module, which could cause previously filtered-out harmful particles to re-enter the air.

[0023] In yet another embodiment of the air purification device according to the invention, which is an alternative to the aforementioned variant and can be combined with other embodiments, a pre-filter module for particle separation is provided upstream of the electrostatic precipitator unit. This pre-filter module is provided with a first switchable bypass through which the ozone-enriched air can be guided upstream of the pre-filter module during system cleaning operation, and which is provided with a second switchable bypass through which the ozone-enriched air flowing through the pre-filter module in the local main flow direction can be guided to the at least one raw air inlet. This variant makes it possible for the ozone-enriched air to also flow through the pre-filter module in its local main flow direction during system cleaning operation before this air is guided to the exhaust air duct arrangement. This also allows the pre-filter module to be disinfected.

[0024] The problem addressed to the air purification system is solved by the air purification system having the features of claim 11.

[0025] An air purification system for at least one substantially enclosed space, in particular an interior of a vehicle cabin, is provided with an air purification device according to the invention, wherein the at least one space is connected to the at least one raw air inlet of the air purification device by an exhaust air duct arrangement, and wherein the at least one space is connected to the at least one clean air outlet of the air purification device by a clean air duct arrangement. According to the invention, the air purification device is designed such that the ozone-enriched air can be conveyed through the at least one raw air inlet of the air purification device into the exhaust air duct arrangement of the space in the flow reversal mode, also referred to as system cleaning mode.

[0026] In such an air purification system, the cleaning and disinfection effect achievable with the air purification unit according to the invention is extended to the room and its exhaust duct arrangement leading to the air purification unit. The flow reversal operation allows the system's cleaning operation to be extended to the room and its exhaust duct arrangement when the room is not occupied by people (or animals). The ozone also exerts its disinfecting effect there, killing or deactivating biological pollutants that have accumulated, particularly in the exhaust duct arrangement, for example, on the walls there.

[0027] The part of the problem directed to the method for cleaning an air purification device is solved by the method according to claim 12, which according to claim 13 can be used in particular in an air purification system according to the invention, but also in other air purification systems for closed rooms.

[0028] In this method for cleaning an air purification device according to the invention, in which air to be cleaned is conveyed in an air purification mode through at least one raw air inlet in a main flow direction through an electrostatic precipitator unit and through at least one filter module to at least one clean air outlet for cleaned air, and which is switchable between this air purification mode and a system purification mode in which the air flows at least partially countercurrent to the main flow direction through the air purification device, a system purification mode is provided according to the invention in which air in the electrostatic precipitator unit is enriched with ozone generated by the latter and flows through the air purification device in the system purification mode, where it then exits the air purification device through the at least one raw air inlet,During system cleaning operation, the filter modules are not subjected to air flow counter to their respective local main flow direction. The advantages of this method according to the invention correspond to those already listed above in connection with the corresponding device. In particular, it provides a simple, periodically cleaning option for components of the air cleaning device located upstream of the electrostatic precipitator unit in the main flow direction.

[0029] During system cleaning operation, the air filter modules in the air purification system for particle or suspended matter separation should preferably not be flowed countercurrently to the respective local main flow direction. This avoids filter backwashing, as already explained above.

[0030] The part of the problem directed to the method for cleaning an air purification system is solved by a method having the features of claim 14.

[0031] This method for cleaning an air purification system for at least one substantially enclosed room implements the method according to the invention for cleaning the air purification device. The ozone-enriched air exiting the air purification device through the at least one raw air inlet during system cleaning operation is conveyed through the exhaust air duct arrangement into the room, thus exerting a disinfecting and deodorizing effect in the room and its exhaust air duct arrangement. In particular, this also provides a simple, periodically cleaning option for air purification system components located upstream of the air purification device in the main flow direction.

[0032] Finally, the invention also encompasses a vehicle, in particular an aircraft, with an air purification system according to the invention.

[0033] Preferred embodiments of the invention with additional design details and further advantages are described and explained in more detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] It shows: Fig. 1 shows a cross-section through a passenger cabin and a schematic arrangement of a ventilation and air conditioning device in the fuselage of an aircraft; Fig. 2 shows a schematic of the structure of an exemplary embodiment of a vehicle interior air purification system according to the invention in an aircraft; Fig. 3 shows a process diagram of the vehicle interior air purification system according to the invention in air purification mode with the air flow in the main flow direction; Fig. 4 shows a process diagram of a first variant specifically designed for system purification mode with a partial countercurrent air flow; Fig. 5 shows a process diagram of a second variant specifically designed for system purification mode with a partial countercurrent air flow, and Fig.6A process diagram of a third variant specifically designed for system cleaning with a partial countercurrent air flow. PRESENTATION OF PREFERRED EMBODIMENTS

[0035] Fig. 1 shows a schematic cross-section through the fuselage 1' of an aircraft 1, the upper part of which accommodates the passenger cabin of the aircraft 1, i.e., a space 10 forming a vehicle cabin 10', the air of which is purified by an air purification system 2 according to the invention. The air purification system 2 has an air purification device 2', which is usually part of a ventilation and air conditioning system of the aircraft 1 (not described in detail here).

[0036] The supply air Z for the room 10 is guided upwards on the outer sides of the vehicle cabin 10' in supply air ducts 12, 14, which are provided behind a cabin wall paneling 13, 15, and introduced into the vehicle cabin 10' through air outlets 12', 12", 14', 14" in the upper area of ​​the vehicle cabin 10'. The supply air ducts 12, 14 of the vehicle cabin 10' are in fluid communication with supply air ducts 19' below the vehicle cabin 10' and together form a clean air duct arrangement 19.

[0037] The supply air Z descends inside the vehicle cabin 10' and mixes with the air exhaled by the passengers and other body odors of the passengers. It is discharged as exhaust air A in the lower area of ​​the vehicle cabin 10' through exhaust air ducts 16, 16' from the vehicle cabin 10'. The exhaust air ducts 16, 16' of the vehicle cabin 10' are in fluid communication with exhaust air ducts 17' below the vehicle cabin 10' and together form an exhaust air duct arrangement 17 which is in fluid communication with at least one raw air inlet 18 of the air purification device 2'.

[0038] The exhaust air A, containing the harmful particles P, is fed via the exhaust air duct arrangement 17 to the air purification device 2', which is located in a technical compartment 11 in the fuselage of the aircraft 1 below the passenger cabin forming the vehicle cabin 10'. The exhaust air duct arrangement 17, the air purification device 2', and the clean air duct arrangement 19 together form the air purification system 2.

[0039] The exhaust air A from the vehicle cabin 10' is fed to the air purification device 2' through the exhaust air duct arrangement 17 and the raw air inlet 18 and is cleaned in the air purification device 2' of dust, biological air contaminants, for example viruses, bacteria, and fungal spores, and preferably also of chemical air contaminants, for example volatile organic compounds such as hydrocarbons. For this purpose, the air to be cleaned flows through the air purification device 2' in a main flow direction V during air purification operation. The cleaned and, if applicable, conditioned air leaves the air purification device 2' through a clean air outlet 18' and is directed as supply air Z through the clean air duct arrangement 19 back to the supply air ducts 12, 14 of the vehicle cabin 10', i.e., the passenger cabin.

[0040] The Fig. 2 shown as an example in exploded view of the individual components and in Fig. 3The air purification device 2', shown schematically as a flow diagram, has a mechanical pre-filter module 20 with at least one filter medium 21 behind the raw air inlet 18, with which coarser particles are removed from the air. The filter medium 21 can be, for example, a mechanical coarse filter and / or a high-performance particulate filter (EPA filter). This is followed, in the main flow direction V of the air to be purified, by an electrostatic precipitator unit 3 with an electrostatic precipitator module 30, which is preferably surrounded by a shielding device (not shown), and which is described in more detail below. The shielding device shields the surroundings of the electrostatic precipitator module 30 from electromagnetic pulses and forms an EMC shielding device.

[0041] Downstream of the electrostatic precipitator unit 3 with the electrostatic precipitator module 30, in the main flow direction V, is a first mechanical main filter module 22 for particle and suspended matter separation, comprising a filter medium 23 designed as a high-efficiency particulate air (HEPA) filter. The filtered air exiting the first main filter module 22 then enters an optionally provided physico-chemical filter module 24 with an activated carbon filter 25, in which chemical components are removed from the air. In addition to the activated carbon filter 25 or instead of the activated carbon filter 25, a molecular sieve filter can also be provided in the physico-chemical filter module 24, which can also remove chemical substances from the air and deposit them on the filter surface of the molecular sieve filter.Behind the physico-chemical filter module 24, in the main flow direction V, a second mechanical main filter module 26 is provided. Similar to the first main filter module 22, this second mechanical main filter module is designed as a HEPA filter and has a filter medium 27 that removes any particulate matter still present in the air. The filter medium 27 of the second mechanical filter module 26 is also formed by a HEPA filter.

[0042] Between the pre-filter module 20 and the electrostatic precipitator unit 3 or between the electrostatic precipitator unit 3 and the first main filter module 22, an axial fan 29' is provided as an air conveying device 29, the air impeller 29" of which rotates in a forward direction and causes the air flow in the main flow direction V.

[0043] The cleaned air exiting from the second, secondary filter module 26 then enters the supply air duct arrangement 19 from the clean air outlet 18' of the air cleaning device 2' and is returned as supply air Z to the vehicle cabin 10'.

[0044] The first mechanical main filter module 22, the - optionally provided - physical-chemical filter module 24 and the second mechanical main filter module 26 form a filter unit 28 for particle separation and / or for the separation of chemical air pollutants downstream of the electrostatic precipitator module 30. This filter unit 28 can preferably form an integral filter arrangement together with the electrostatic precipitator unit 3 and the pre-filter module.

[0045] The electrostatic precipitator module 30 of the electrostatic precipitator unit 3 has a high-voltage grid as a high-voltage electrode 30' and a control grid as a control electrode 30", which are slightly spaced apart from one another in the flow direction V and between which a high-voltage electrical voltage provided by a power supply module 32 is applied. The high-voltage electrode 30' and the control electrode 30" form a first electrostatic precipitator stage 34. Instead of flow-through grid electrodes, plate electrodes can also be provided as high-voltage electrodes and control electrodes, the interelectrode spaces of which are flowed through by the air to be cleaned. The high-voltage electrodes and the control electrodes are preferably subjected to a high-voltage electrical voltage (DC voltage) of, for example, 3 kV to 10 kV.

[0046] Due to the high electrical voltage between the high-voltage electrode 30' and the control electrode 30", an ionization field is formed in the electrostatic precipitator module 30 through electrical discharges, through which the mechanically pre-filtered exhaust air A passes. The electrostatic precipitator module 30 therefore forms an ionizer in which a cold plasma is generated. In this ionization field, viruses, bacteria, mites, fungal spores, etc., are killed or biologically inactivated and ideally clump together to form larger particles, which are separated from the air in the downstream first mechanical main filter module 22 or in the further downstream second mechanical main filter module 26. Ionization in the electrostatic precipitator module 30 also produces gaseous ozone, which contributes to the disinfection of the air and also of the first main filter module 22 during air purification operation and is removed from the air again in the physico-chemical filter module.

[0047] In the main flow direction V, a third electrode 30‴ is arranged downstream of the first mechanical main filter module 22 or inside the first mechanical main filter module 22. The third electrode 30‴, which has, for example, a mesh or grid as its electrode surface, is arranged. The third electrode 30‴, which is connected to electrical ground, forms, together with the high-voltage electrode 30' and / or the control electrode 30" of the ionizer, a second electrostatic precipitator stage 36. A constant, lower DC voltage of, for example, 1000 V is applied between the first electrostatic precipitator stage 34 and the third electrode 26. Thus, an electrically positive voltage, measured relative to ground, is present in both the first electrostatic precipitator stage 34 and the second electrostatic precipitator stage 36, with the positive voltage in the first electrostatic precipitator stage 34 being higher than the positive voltage in the second electrostatic precipitator stage 36.Thus, despite lower voltages than in conventional systems, a strong electric field (typically up to 900 kV / m) is created by the relative potentials of the electrodes 30' and 30" within the electrostatic precipitator module 30 forming one ionizer, and another, weaker field between the ionizer and the third electrode 30‴, which accelerates the particles charged in the ionizer towards the first mechanical main filter module 22 and thus separates them there.

[0048] The air cleaning device 2' is designed such that it can be operated at least partially in a system cleaning mode, in which ambient air sucked in through an auxiliary air inlet 18" can be conveyed through the electrostatic precipitator unit 30 and in counterflow V' to the main flow direction V through the at least one raw air inlet 18 of the air cleaning device 2' into the exhaust air duct arrangement 17 of the vehicle cabin 10' forming the space 10. In this system cleaning mode, the electrostatic precipitator unit 30 is activated to generate ozone.

[0049] While the electrostatic precipitator unit 30 operates in a first operating state in air purification mode, i.e., when air to be purified flows through it in the main flow direction V, in which it produces only a smaller amount of ozone, it operates in a second operating state in system purification mode, i.e., in system purification mode, in which it produces a larger amount of ozone. The air enriched with this larger amount of ozone flows countercurrently to the main flow direction into the exhaust air ducts 16, 16', and 17' of the exhaust air duct arrangement 17 and disinfects their interior spaces and their inner walls.

[0050] In the simplest variant, to achieve system cleaning operation, the air impeller 29" of the axial fan 29' is operated with a direction of rotation opposite to the forward direction, whereby the air from the axial fan 29' is conveyed in countercurrent V' to the main flow direction V through the electrostatic precipitator module 30 and the pre-filter module 20 into the exhaust air ducts 16, 16' and 17' of the exhaust air duct arrangement 17, wherein the air in the electrostatic precipitator module 30 operating in the second operating state is enriched with ozone to achieve the increased ozone concentration.

[0051] In the Fig. 4In the schematically illustrated special variant of the air purification device 2' of an air purification system 2 according to the invention, a switchable bypass 4 is provided parallel to the pre-filter module 20 provided upstream of the electrostatic precipitator unit 3, which is formed by a bypass duct 40. Through this bypass 4, the air flowing in countercurrent V' from the electrostatic precipitator unit 3 and enriched with ozone is guided past the pre-filter module 20 to the at least one raw air inlet 18 and from there further into the exhaust air duct arrangement 17. This prevents backwashing of the pre-filter module 20 during system cleaning operation.A first shut-off valve 41—shown in the figures as a vertical double line—is provided upstream of the first mechanical main filter module 22 and, in all variants, blocks the air flow path from the electrostatic precipitator unit 3 through the downstream filter modules 22, 24, and 26 to the clean air outlet 18' during system cleaning operation, thus enabling system cleaning operation when shut off. A second shut-off valve 42 upstream of the pre-filter module 20 and a third shut-off valve 43 downstream of the pre-filter module 20 are each closed and prevent reverse flow through the pre-filter module 20.

[0052] At the Fig. 5In the modified embodiment of the special variant of the air purification device 2' of an air purification system 2 according to the invention shown, a first switchable bypass 4' is provided parallel to the pre-filter module 20 provided upstream of the electrostatic precipitator unit 3, said first switchable bypass being formed by a first return duct 40' through which the ozone-enriched air can be guided from the electrostatic precipitator unit 3 upstream of the pre-filter module 20 during system cleaning operation. The ozone-enriched air then flows locally in the main flow direction V through the pre-filter module 20. The ozone-enriched air emerging from the pre-filter module 20 is subsequently guided through a second switchable bypass 4", formed by a second return duct 40", to the at least one raw air inlet 18, from where it flows counter to the main flow direction V into the exhaust air duct arrangement 17.The second shut-off valve 42 and the third shut-off valve 43 are arranged such that, when closed, the described air flow through the pre-filter module 20 is enabled. In this variant, the pre-filter module 20 is also locally flowed through and disinfected by the ozone-enriched air in the main flow direction V.

[0053] At the Fig. 6In the schematically shown alternative embodiment of the invention, the auxiliary air inlet 18‴ is provided upstream of the electrostatic precipitator unit 3 in the main flow direction, so that the electrostatic precipitator unit 30 is also flowed forwards in system cleaning mode, wherein a return duct 40‴ is provided as a switchable bypass 4‴ as a flow reversal device, through which the air flowing through the electrostatic precipitator unit 3 in system cleaning mode is guided past the pre-filter 20 back to the raw air inlet 18 and into the exhaust air duct arrangement 17. The second shut-off valve 42 upstream of the pre-filter module 20 and the third shut-off valve 43 downstream of the pre-filter module 20 are closed in order to prevent backward flow through the pre-filter module 20.

[0054] The arrows in the Fig. 3 , 4 , 5 and 6 indicate the local flow direction of the air in air cleaning mode ( Fig. 3) and in system cleaning mode ( Fig. 4 , 5 and 6 ).

[0055] The system cleaning operation according to the invention can of course also be achieved if the air flows through the electrostatic precipitator unit 3 and / or the air conveying device 29 in the main flow direction V, and the ozone-enriched air is then redirected and guided through corresponding return ducts (not shown) to the raw air inlet 18. Such variants are also encompassed by the invention.

[0056] Reference signs in the claims, the description and the drawings serve only to improve the understanding of the invention and are not intended to limit the scope of protection. List of reference symbols

[0057] They refer to: 1 Aircraft 1 Fuselage 2 Air cleaning system 2 Air cleaning device 3 Electrostatic precipitator unit 4 Switchable bypass 4 First switchable bypass 4 Second switchable bypass 4 Switchable bypass 10 Room 10 Vehicle cabin 11 Technical room 12 Supply air duct 12 Air outlet 12 Air outlet 13 Cabin wall paneling 14 Supply air duct 14 Air outlet 14 Air outlet 15 Cabin wall paneling 16 Exhaust air duct 16 Exhaust air duct 17 Exhaust air duct arrangement 17 Exhaust air ducts 18 Raw air inlet 18 Clean air outlet 18 Auxiliary air inlet 18 Auxiliary air inlet 19 Clean air duct arrangement 19 Supply air ducts 20 (Mechanical) pre-filter module 21 Filter medium 22 First (mechanical) Main filter module 23 Filter medium 24 Physical-chemical main filter module 25 Activated carbon filter 26 Second (mechanical) main filter module 27 Filter medium 28 Integral filter assembly 29 Air conveying device 29 Axial fan 29 Air impeller 30 Electrostatic precipitator module 30 High-voltage electrode 30 Control electrode 30 Third electrode 32 Power supply module 34 FirstElectrostatic precipitator stage 36 Second electrostatic precipitator stage 40 Bypass channel 40 First return channel 40 Second return channel 40 Return channel 41 First shut-off valve 42 Second shut-off valve 43 Third shut-off valve AExhaust air PPolluting particles VMain flow direction V'Counterflow ZSupply air

Claims

1. An air purification device (2') comprising at least one electro filter unit (3), at least one air filter module (20, 22, 24, 26) and at least one air conveying device (29) for conveying air drawn in through at least one raw air inlet (18) for air to be purified in a main flow direction (V) through the electro filter unit (3) and through the at least one air filter module (20, 22, 24, 26) to at least one clean air outlet (18') for purified air, wherein the air purification device (2') can be switched between an air purification operation, in which the air flows in the main flow direction (V), and a system cleaning operation in which the air flows at least partially in counterflow (V') to the main flow direction (V) through the air purification device (2') and exits the air purification device (2') through the at least one raw air inlet (18), and wherein the electro filter unit (3) is activated or activatable in the system cleaning operation for generating ozone to enrich the air flowing through the electro filter unit (3) with ozone, characterized in that the air purification device (2') is designed in such a way that the air does not flow through air filter modules (20, 22, 24, 26) in counterflow to their respective local main flow direction (V) during system cleaning operation.

2. Air purification device according to claim 1, characterized in that the air purification device (2') is designed in such a way that the air does not flow through the air filter modules (20, 22, 26) for particle or suspended matter separation in counterflow to the local main flow direction (V) during system cleaning operation.

3. Air purification device according to claim 1 or 2, characterized in that the air purification device (2') is designed in such a way that, in system cleaning operation, at least a part of the air filter modules (20, 22, 24, 26) has the ozone-enriched air flowing through in the local main flow direction (V).

4. Air purification device according to any of the preceding claims, characterized in that the air conveying direction of the air conveying device (29) can be reversed in order to carry out the flow reversal operation.

5. Air purification device according to any of the preceding claims, characterized in that the electro filter unit (3) is designed to produce a smaller amount of ozone in a first operating state than in a second operating state, and in that the electro filter unit (3) is switchable or switched to the second operating state in the flow reversal operation of the air conveying device (29).

6. Air purification device according to any of the preceding claims, characterized in that at least one filter unit (28) having at least one air filter module (22, 26) for particle separation and / or having at least one air filter module (24) for the separation of chemical air pollutants is provided downstream of the electro filter unit (3) in the main flow direction (V), and in that the flow path of the air from the electro filter unit (3) through this downstream filter unit (28) to the clean air outlet (18') can be shut off or blocked off in flow reversal operation.

7. Air purification device according to any of the preceding claims, characterized in that the air purification device (2') is provided with an auxiliary air inlet (18") through which air can be supplied to the electro filter unit (3) during system cleaning operation.

8. Air purification device according to claim 7, characterized in that the auxiliary air inlet (18") is provided downstream of the electro filter unit (3) in the main flow direction (V) of the air.

9. Air purification device according to any of the preceding claims, characterized in that a prefilter module (20) for particle separation is provided upstream of the electro filter unit (3), which prefilter module (20) is provided with a switchable bypass (4; 4‴) through which the air enriched with ozone can be guided past the prefilter module (20) to the at least one raw air inlet (18) during system cleaning operation.

10. Air purification device according to any one of claims 1 to 8, characterized in that a prefilter module (20) for particle separation is provided upstream of the electro filter unit (3), which prefilter module (20) is provided with a first switchable bypass (4') through which the ozone-enriched air can be passed upstream of the prefilter module (20) during system cleaning operation, and which is provided with a second switchable bypass (40"), through which the ozone-enriched air flowing through the prefilter module (20) in the local main flow direction (V) can be guided to the at least one raw air inlet (18).

11. Air purification system for at least one substantially closed room (10), in particular an interior of a vehicle cabin (10'), with an air purification device (2') according to one of the preceding claims, wherein the at least one room (10) is connected to the at least one raw air inlet (18) of the air purification device (2') by an exhaust air duct arrangement (17), and wherein the at least one room (10) is connected to the at least one clean air outlet (18') of the air purification device (2') by a clean air duct arrangement (19), characterized in that the air purification device (2') is designed in such a way that the air enriched with ozone can be conveyed through the at least one raw air inlet (18) of the air purification device (2') into the exhaust air duct arrangement (17) of the room (10) during system cleaning operation.

12. Method for cleaning an air purification device (2') according to one of claims 1 to 10, in which air to be purified is conveyed in an air purification operation through at least one raw air inlet (18) in a main flow direction (V) through an electro filter unit (3) and through at least one filter module (20, 22, 24, 26) to at least one clean air outlet (18') for purified air and which is switchable between this air purification operation and a system cleaning operation in which the air flows through the air purification device (2') at least partially in counterflow (V') to the main flow direction (V), characterized by a system cleaning operation in which air in the electro filter unit (3) is enriched with ozone generated by the latter and flows through the air purification device (2') in the system cleaning operation and exits from the air purification device (2') through the at least one raw air inlet (18), wherein the filter modules (20, 22, 24, 26) are not flowed through by the air against their respective local main flow direction (V) in the system cleaning operation.

13. Method according to claim 12, characterized in that in that, during system cleaning operation, there is no flow through air filter modules (20, 22, 26) present in the air purification device (2') for particle or suspended matter separation in counterflow to the respective local main flow direction (V).

14. Method for cleaning an air purification system (2) for at least one substantially closed room (10) according to claim 11, wherein the method for cleaning the air purification device (2') is performed according to claim 12, characterized in that the air which, during system cleaning operation, emerges from the air purification device (2') through the at least one raw air inlet (18) and which is enriched with ozone is conveyed into the room (10) through the exhaust air duct arrangement (17).

15. Vehicle, in particular aircraft, with an air purification system according to claim 11.