Ionization device, filtering device and motor vehicle

Abstract

The invention relates to an ionization device, a filtering device and a motor vehicle. In particular for an electrostatic air filter device (6), preferably of a motor vehicle (1), comprising:-a voltage generator (12), which has a first voltage connection (13) and a second voltage connection (14) and which is designed to generate a high voltage between the first voltage connection (13) and the second voltage connection (14), -at least one emitter electrode (15) which is electrically connected to the first voltage connection (13),-at least one counter electrode (16) which is spaced apart from the emitter electrode (15) and which is electrically connected to the electrical ground (M). When the mating electrode (16) is electrically connected to the second voltage terminal (14), and when the emitter electrode (15) and the mating electrode (16) are electrically connected to the ground (M) in a high-resistance manner, operational safety can be improved.

Description

Technical Field

[0001] The present invention relates to an ionization device for an electrostatic air filtration device for preferably a motor vehicle according to the preamble of claim 1. The present invention also relates to an electrostatic filtration device for a motor vehicle, which is equipped with such an ionization device. In addition, the present invention also relates to a motor vehicle equipped with such a filtration device. Background Art

[0002] For comfortable and healthy air quality, harmful substances such as particulate matter, harmful gases such as hydrocarbons and nitrogen oxides, and unpleasant odors such as ammonia, trimethylamine, and hydrogen sulfide must be removed from the air in the vehicle interior space or the passenger compartment of the vehicle and the air supplied to the passenger compartment. Here, a particularly serious problem in Asian urban spaces is the high concentration of particulate matter pollution in outdoor air. In big cities, the daily average value of these particulate matter pollutions often exceeds the PM2.5 value or the daily average value of 15 μg / m 3 specified by the WHO (World Health Organization). Nowadays, dust entering the vehicle interior space through the fresh air device is mostly removed by the filter element of the filter device arranged in the fresh air device, wherein the filter element is designed as a particulate filter and has a fiber filter layer for removing particles. Such a filter element is crucial for the air quality in the vehicle interior space.

[0003] In the fresh air device, which usually also includes an air conditioning device, only a small amount of installation space is available for the filter element. The air conditioning device and the filter device are also often integrated in a common housing. Therefore, these filter elements must have a low flow resistance and / or pressure loss, so that a predetermined air flow can still be transported into the vehicle interior space despite this and thus, for example, safety requirements such as avoiding window fogging can be met. The disadvantage of this is that the filter fiber layer for separating particles is mostly designed to be extremely porous and the mechanical dust separation degree of the filter element is therefore mostly only very low. Therefore, many filter medium manufacturers and / or filter fiber layer manufacturers ensure that they are electrostatically charged during the production process of the filter medium. Thereby, during subsequent operation, the usually electrostatically charged particles are better separated by the electrostatic separation of the filter medium. Due to this separation mechanism, even extremely small particles of <0.3 μm can be separated without having to increase the flow resistance and / or pressure loss of the filter element. However, the static charge applied during the production process quickly fails with the aging of the filter element during vehicle operation and the increasingly high dust content of the filter element. The static charge of the filter therefore mainly only acts at the beginning of its life cycle. Depending on the degree of outdoor air pollution, a significant loss of static electricity may already occur after a few weeks or months.

[0004] The so-called ionizer or ionization device utilizes a mechanism for charging particulate static electricity. Insofar as an air flow is connected upstream of a filter element, this causes the particles contained in the air flow to be charged. In addition, due to the ions introduced into the air, the filter element is also slightly recharged. This ensures an improvement in the separation performance added to the purely mechanical separation performance of the filter element through electrostatic particle separation maintained over a longer period of time.

[0005] The ionization device used generally has a negative emission electrode or a negative injection electrode for generating a corona discharge for charging particles. In a negative corona discharge, electrons appear at an injection electrode that often has a row of a plurality of sharp profiles in the form of, for example, extremely sharp thorns or needles, and the electrons are strongly accelerated especially in the near electric field of the injection electrode. Therefore, the electrons strike gas molecules, which then lose another electron due to the strike and are thus positively ionized. As a result, a positive gas molecule or gas ion and two electrons are generated. This effect mainly occurs very close to the injection electrode at extremely high field strengths. At a greater distance from the injection electrode, mainly fast-moving electrons attach to gas molecules and thereby form negative gas ions. In a negative corona discharge, more gas ions are formed than in a positive corona discharge because the electrons migrate faster due to their small size. This is beneficial for the charging of particles and thus also for separation in the subsequent filter element.

[0006] Therefore, positive ions and negative ions are present in the air flow, and they attach to the particles again. However, the net charge is always negative for a negative corona discharge because electrons are introduced into the air flow.

[0007] The static charging of the filter element decreases with an increase in load or an increase in the operating time because the static electricity or static charging of the filter element is lost due to the dust layer on the filter element.

[0008] Generic ionization devices are known, for example, from WO 2020 / 263171 A1. The ionization device includes a voltage generator that has a first voltage terminal and a second voltage terminal and is configured to generate a high voltage between the first voltage terminal and the second voltage terminal. The ionization device has an emission electrode that is electrically connected to the first voltage terminal. The ionization device also has a counter electrode that is spaced apart from the emission electrode and is electrically connected to an electrical ground. In the known ionization device, the second voltage terminal of the voltage generator is also connected to the ground.

[0009] Further ionization devices are known, for example, from US 2021 / 0 021 107 A1, KR 10-2 205 159 B1, WO 2021 / 226639 A2, EP 3 056 364 B1, and EP 3 488 933 A1.

[0010] A general problem in this case with ionization devices and in particular electrostatic filters equipped with such ionization devices is that during operation, high voltages are present at the injection electrode and it is theoretically possible to touch the injection electrode, for example, during maintenance work to replace the filter element. When the ignition is switched on, the ionization device can be active, so that high voltages are present at the injection electrode. For example, a person (male / female / plural) working near the injection electrode to replace the filter element grounds and / or touches the vehicle and is thus connected to the vehicle ground, so that there is a risk of discharge of the injection electrode via the person, especially when the injection electrode is touched unintentionally. Summary of the invention

[0011] The object of the present invention is to specify an improved embodiment for an ionization device of the aforementioned type or for a filter device equipped with an ionization device of the aforementioned type or for a motor vehicle equipped with such a filter device, which embodiment is distinguished in particular by increased safety.

[0012] According to the invention, this object is achieved by the subject matter of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.

[0013] The general idea underlying the present invention is to configure the ionization device in such a way that a system electrically isolated from the earth is created for the spray electrode, i.e. a so-called IT system or IT network, wherein IT stands for Isoliert (insulated from the earth or connected to the earth with high impedance) and Terrar (directly connected to the earth). An IT network is therefore an ungrounded electrical network that is completely or at least as electrically isolated as possible from the electrical ground. As a result, a person can touch the spray electrode without the current loop being closed and a discharge occurring. In this regard, an effective touch protection is created here, which increases the operating safety of the ionization device and the filter device equipped with the ionization device or the vehicle equipped with the filter device.

[0014] In the present context, “configuration” is synonymous with “design” and / or “set” and / or “programmed”, so that the expression “configured so that” is synonymous with the expression “designed and / or set and / or programmed so that”.

[0015] For this purpose, it is specifically proposed that the emitting electrode and the cooperating electrode be electrically connected to the grounding part in a high-impedance manner. Here, a complete galvanic separation is not aimed for, but rather a high-impedance connection is established, in particular via a high-impedance resistor, which excludes critical or dangerous current flows. In the context of the present invention, a connection or resistor is considered to be high-impedance if the resistance value is at least 500 times greater than the voltage present in the system or network. In the present case, the respective high-impedance resistance values are thus at least 500 times greater than the high voltage generated by the voltage generator. At a high voltage of, for example, 10 kV, the high-impedance connection or resistor thus has a resistance value of at least 5 megaohms. Due to these high-impedance connections, the emitting electrode and the cooperating electrode are nearly electrically insulated or separated from the grounding part. In addition, it is proposed for an IT network that the cooperating electrode be electrically connected to the second voltage terminal. Thus, a high voltage is built up only between the emitting electrode and the cooperating electrode, but not with respect to the grounding part or the earth.

[0016] Furthermore, according to an advantageous embodiment, the emitting electrode can be electrically connected to the first voltage terminal in a high-impedance manner. Thereby, a current limitation is achieved, which reduces the possible current flow to a harmless value in the case of contact with the emitting electrode.

[0017] According to an advantageous embodiment, the emitting electrode can be electrically connected to the first voltage terminal in a high-impedance manner via a first ohmic resistor. This first resistor represents both the above-mentioned current limiter and also a touch protection measure.

[0018] According to a particular embodiment, this first resistor can have a resistance value of at least 5 megaohms and at most 20 megaohms, in particular a resistance value of 11 megaohms or 11 megaohms ± 20%. In this way, the first resistor allows the flow of a smaller current, but the smaller current is necessary for generating a corona discharge during the operation of the ionization device.

[0019] In another embodiment, it can be provided that the emitting electrode is electrically connected to the grounding part in a high-impedance manner via a second ohmic resistor. The use of the ohmic resistor here enables a simple and inexpensive structure. Suitably, the second resistor can have a resistance value of at least 100 megaohms and at most 500 megaohms. Preferably, the resistance value of the second resistor is between 400 megaohms and 500 megaohms. In this resistance range, a significant current flow from the emitting electrode to the grounding part can be nearly excluded.

[0020] Preferably, the cooperating electrode is electrically connected to the grounding part in a high-impedance manner via a third ohmic resistor. The use of the ohmic resistor here also enables an inexpensive and reliable implementation. In particular, the third resistor can have a resistance value of at least 100 megaohms and at most 500 megaohms. Preferably, the resistance value of the third resistor is between 100 megaohms and 200 megaohms. Here too, a significant current from the cooperating electrode to the grounding part can be excluded.

[0021] The following configuration has proven to be particularly advantageous, wherein the second resistor and the third resistor together have a resistance value of 500 MΩ to 700 MΩ. Preferably, the sum is 600 MΩ or 600 MΩ ± 10%. Additionally or alternatively, it can be provided that the second resistor has a greater resistance value than the third resistor, in particular at least twice as large. This is advantageous because there is a greater potential difference relative to the ground at the emission electrode than between the mating electrode and the ground. By using a higher resistance value for the second resistor, touch protection can be improved here. According to a preferred embodiment, it can be additionally or alternatively provided that the connection site that electrically connects the emission electrode and the mating electrode to the ground in a high-impedance manner is arranged between the second resistor and the third resistor.

[0022] According to an advantageous embodiment, the voltage generator can have a high-voltage power supply for providing and / or generating a high voltage and an isolation transformer, which is electrically connected to the high-voltage power supply on the primary side and has a first voltage terminal and a second voltage terminal on the secondary side. By using such an isolation transformer, direct contact with the high-voltage power supply has been excluded, which improves the operating safety.

[0023] Suitably, the voltage generator can be designed to generate a high voltage of at least 7 kV, at most 10 kV, and preferably 8 kV. It has been shown that in the case of these voltage values, particularly good effects regarding the ionization of particles carried in the air stream can be achieved.

[0024] The electrostatic filter device for a motor vehicle according to the invention includes a flow channel for guiding an air stream, a filter element configured as a particle filter, and an ionization device of the aforementioned type. The filter element is arranged in the flow channel such that the air stream passes through the filter element. In the filter device, the emission electrode and the mating electrode are arranged upstream of the filter element in the flow channel with respect to the air stream, such that the air stream passes through between the emission electrode and the mating electrode. During operation of the filter device, a corona discharge is established between the emission electrode and the mating electrode. The air stream now passes through this corona discharge, so that the particles transported in the air stream especially directly encounter electrons. In particular, the filter element can be electrostatically charged here in order to improve the adhesion of the ionized particles. The ionization device can also promote the regeneration of at least part of the electrostatic charge of the filter element during operation.

[0025] A motor vehicle according to the invention includes a vehicle interior space and a fresh air device for delivering fresh air from the vehicle's surroundings to the vehicle interior space. An electronic filter device of the aforementioned type is arranged in the fresh air device such that the fresh air flows through the flow channel of the filter device and an air stream is formed there.

[0026] In an advantageous embodiment, the grounding part of the ionization device can be formed by the electrical vehicle grounding part. Additionally or alternatively, the motor vehicle can have an air conditioning device for air conditioning fresh air, and the air conditioning device is arranged downstream of the filter device in the fresh air device with respect to the flow direction of the fresh air. It is hereby expressly stated that the air conditioning device and the filter device can be suitably arranged in a common housing.

[0027] Further important features and advantages of the present invention result from the dependent claims, the drawings and the associated description of the drawings.

[0028] It goes without saying that the features described above and those to be explained below can be used not only in the respectively described combinations, but also in other combinations or individually, without departing from the scope of the present invention defined by the claims. Components of the superordinate units mentioned above and those to be mentioned below, such as individually labeled devices, equipment or assemblies, can form separate components or parts of the unit or integrated regions or sections of the unit, even if this is shown differently in the drawings.

[0029] Preferred embodiments of the present invention are shown 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. Description of the Drawings

[0030] Wherein:

[0031] Figure 1 A highly simplified schematic diagram of a motor vehicle in the area of a fresh air device having an ionization device is schematically shown;

[0032] Figure 2 A highly simplified, circuit-diagrammatic schematic diagram of the ionization device is schematically shown. Detailed Description of the Invention

[0033] According to Figure 1 , the motor vehicle 1, only partially shown, includes a vehicle interior space 2 and a fresh air device 3, and the fresh air device is configured such that fresh air from the surroundings 4 of the vehicle 1 can be conveyed to the vehicle interior space 2 by means of the fresh air device 3. Thereby, an air flow 5 shown by arrows in Figure 1 and Figure 2 is formed. The fresh air device 3 includes an electrostatic filter device 6, and the filter device has a flow channel 7. The filter device 6 is hereby connected into the fresh air device 3 such that the air flow 5 also flows through the flow channel 7.

[0034] The electrostatic filter device 6 includes a flow channel 7 for guiding the air flow 5 and a filter element 8, which is suitably configured as a particle filter and arranged in the flow channel 7 such that the air flow 5 passes through the filter element 8. The filter device 6 is also equipped with an ionization device 9 by means of which the particles carried in the air flow 5 can be ionized in order to improve the adhesion of the particles to the filter element 8. In particular, the filter element 8 can be electrostatically charged here in order to improve the adhesion of the ionized particles.

[0035] The vehicle 1 can also be equipped with an air conditioning device 10 for conditioning the air flow 5 or the fresh air. The air conditioning device 10 can here be equipped in a conventional manner with a cooler and / or a heater (not shown here), so that the fresh air can be cooled or heated and, if necessary, dried as required. The air conditioning device 10 is suitably connected into the fresh air device 3 such that the air conditioning device is arranged downstream of the filter device 6 with respect to the air flow 5, i.e. with respect to the flow direction of the fresh air, and can be passed through by the air flow 5. The air conditioning device 10 and the filter device 6 can be suitably integrated into a common housing, but this is not shown here. In addition, the vehicle 1 can have a vehicle ground connection 11, which is usually formed by the vehicle body of the vehicle 1.

[0036] According to Figure 2 , the ionization device 9 includes a voltage generator 12, which has a first voltage terminal 13 and a second voltage terminal 14. The voltage generator 12 is also configured to generate a high voltage between the first voltage terminal 13 and the second voltage terminal 14. The ionization device 9 also has at least one emission electrode 15 and at least one counter electrode 16. The emission electrode 15 is electrically connected to the first voltage terminal 13. The counter electrode 16 is connected to the electrical ground M and is also arranged at a distance from the emission electrode 15. The emission electrode 15 is designed here as a spray electrode and has at least one pointed or tapering profile 17, which can be designed as a spike or a needle. The emission electrode 15 can generally have a plurality of such pointed profiles 17, which are spaced apart from one another and arranged adjacent to one another especially in the longitudinal direction of the emission electrode 15. The longitudinal direction of the emission electrode 15 extends perpendicular to the drawing plane in the Figure 2 example, so that only one such pointed profile 17 can be seen here. Each respective pointed profile 17 projects from the substrate 18 of the emission electrode 15 parallel to the flow direction of the air flow 5. The counter electrode 16 is designed here as plate-shaped and extends in a plate plane, which is parallel to the flow direction of the air flow 5 and parallel to the longitudinal direction of the emission electrode 15. The plate plane of the counter electrode 16 is perpendicular to the drawing plane in the Figure 2 figure. In the filter device 6, the emission electrode 15 and the counter electrode 16 are arranged according to Figure 2It is arranged upstream of the filter element 8 with respect to the air flow 5 in the flow channel 7 such that the air flow 5 passes through between the emission electrode 15 and the counter electrode 16. Generally, a plurality of emission electrodes 15 and a plurality of counter electrodes 16 can be provided, which are arranged adjacent to each other transversely to the flow direction and spaced apart from each other.

[0037] In the ionization device 9 proposed here, the counter electrode 16 is electrically connected to the second voltage terminal 14 of the voltage generator 12. It is also stipulated here that the emission electrode 15 and the counter electrode 16 are electrically connected to the ground part M in a high-resistance manner. Additionally, it can be stipulated that the emission electrode 15 is also electrically connected to the first voltage terminal 13 in a high-resistance manner. This high-resistance electrical connection of the emission electrode 15 to the first voltage terminal 13 is Figure 2 implemented by means of a first ohmic resistor R1 in the example, which is connected in series with the emission electrode 15 or in series with the first voltage terminal 13. The first resistor R1 is designed to be high-resistance and can have a resistance value in the range of 5 megaohms to 20 megaohms. According to the preferred embodiment shown, the first resistor R1 can have a resistance value of 11 megaohms.

[0038] The emission electrode 15 can also be electrically connected to the ground part M in a high-resistance manner via a second ohmic resistor R2. The connection of the emission electrode 15 to the ground part M via the second resistor R2 and the connection of the emission electrode 15 to the first voltage terminal 13 via the first resistor R1 are implemented in parallel. The second resistor R2 can have a resistance value in the range of 100 megaohms to 500 megaohms. In the preferred embodiment shown, the second resistor R2 can have a resistance value of 500 megaohms.

[0039] The counter electrode 16 can be electrically connected to the ground in a high-resistance manner via a third ohmic resistor R3. The connection of the counter electrode 16 to the ground part M via the third resistor R3 and the connection of the counter electrode 16 to the second voltage terminal 14 are implemented in parallel. The third resistor R3 can have a resistance value in the range of 100 megaohms to 500 megaohms. In the preferred embodiment shown, the third resistor R3 can have a resistance value of 100 megaohms.

[0040] Since on the one hand both the emission electrode 15 and the counter electrode 16 are connected to the ground part M in a high-resistance manner and on the other hand an electrical short circuit between the emission electrode 15 and the counter electrode 16 is to be avoided, the connection part 23 that electrically connects the emission electrode 15 and the counter electrode 16 to the ground part M in a high-resistance manner is located between the second resistor R2 and the third resistor R3.

[0041] Suitably, the following configuration is implemented in which the emission electrode 15 and the mating electrode 16 are in high-resistance contact with the ground portion M, that is, the second resistor R2 and the third resistor R3 have a total resistance value of 500 megaohms to 700 megaohms and preferably 600 megaohms. In the shown preferred embodiment, the second resistor R2 has a resistance value of 500 megaohms, while the third resistor R3 has a resistance value of 100 megaohms. Thus, a total value of 600 megaohms for the resistance values of the second resistor R2 and the third resistor R3 is obtained. In addition, the following embodiment is preferred, in which the second resistor R2 has a larger resistance value than the third resistor R3. Suitably, the second resistor R2 is selected in terms of its resistance value to be at least twice as large as the third resistor R3. In the shown preferred embodiment, the second resistor R2 having a resistance value of 500 megaohms is five times as large as the third resistor R3 having a resistance value of 100 megaohms.

[0042] The voltage generator 12 includes a high-voltage power supply 19 for providing or generating a high voltage. The voltage generator 12 also has an isolation transformer 20 which is electrically connected to the high-voltage power supply 19 on the primary side and has a first voltage terminal 13 and a second voltage terminal 14 on the secondary side. The voltage generator 12 or the high-voltage power supply 19 can be configured such that a high voltage in the range of 7 kV to 10 kV can be generated thereby. Before the shown preferred embodiment, a high voltage of 8 kV was used.

[0043] During operation, the ionization device 9 generates a corona discharge 21 which starts from the spikes of the pointed profile 17 and spreads towards the mating electrode 16. The corona discharge 21 is Figure 2 shown by a dashed line. The ionization device 9 is arranged in the filter device 6 or in the flow channel 7 of the filter device such that the air flow 5 passes through the corona discharge 21. When using a vehicle, the ground portion M is preferably formed by the vehicle ground 11.

[0044] The high-ohmic connection of the emitting electrode 15 and the cooperating electrode 16 to the ground part M generates an IT network 22 within the ionization device 9 and thus represents an ungrounded system. Due to the extremely high ohmic resistances R2 and R3, the emitting electrode 15 and the cooperating electrode 16 are nearly galvanically separated from the ground part M. Therefore, a grounded person can operate safely in the area of the emitting electrode 15. Even when there is a high voltage on the emitting electrode, touching the emitting electrode 15 is not dangerous. In addition, the first resistor R1 serves as a current limiter, which reduces the current flowing therethrough to a non-dangerous value when the emitting electrode 15 discharges through a grounded person. Even if, for example, the first resistor R1 fails and in principle a large current may flow away through the emitting electrode 15, touching the emitting electrode 15 is always not dangerous for a grounded person because the high-ohmic connection to the ground part M does not allow current flow between the ungrounded IT system 22 and the grounded person.

[0045] In summary, the ionization device 9 proposed here is characterized in that both the cooperating electrode 15 and the emitting electrode 16 are electrically connected to the ground part M in a high-ohmic manner or are insulated from the ground part M in a high-ohmic manner and are nearly galvanically separated therefrom. Thus, an IT network 22, i.e., a system insulated from the earth, is constructed. In the IT network 22, conductors can be touched without problems and without danger. Current always requires a conductor for flow and a return conductor. This is not the case in the IT network 22 and when touching only one conductor. When the resistance is 500 times greater than the voltage, it is considered high-ohmic here. That is to say, at 10 kV, all resistances must be greater than 5 megaohms. In particular, a voltage source 19 insulated via an isolation transformer 20 is implemented for the IT network 22, and this voltage source provides or generates a high voltage of at least 7 kV, preferably 8 kV, and at most 10 kV. The emitting electrode 15 is connected in series with the first resistor R1 for current limitation. The first resistor R1 has a resistance value of at least 5 megaohms, at most 20 megaohms, and preferably 11 megaohms. In order to isolate the emitting electrode 15 from the ground part M in a high-ohmic manner, the second resistor R2 is used for the emitting electrode 15 and the third resistor R3 is used for the cooperating electrode 16. Resistance values of at least 100 megaohms and at most 500 megaohms are suitable for the second resistor R2 and the third resistor R3, respectively, and a sum of 600 megaohms is preferred. In addition, the resistance value of the second resistor R2 is preferably greater than the resistance value of the third resistor R3.

Claims

1. An ionization device (9) for an electrostatic air filter device (6), preferably for a motor vehicle (1), the ionization device comprising: - a voltage generator (12), which has a first voltage terminal (13) and a second voltage terminal (14) and is configured to generate a high voltage between the first voltage terminal (13) and the second voltage terminal (14), - at least one transmitting electrode (15), said transmitting electrode being electrically connected to said first voltage terminal (13), - at least one mating electrode (16) spaced apart from the emitting electrode (15), the mating electrode being electrically connected to an electrical ground (M), It is characterized in that - the matching electrode (16) is electrically connected to the second voltage terminal (14), - The emitting electrode (15) and the matching electrode (16) are electrically connected to the ground portion (M) in a high-resistance manner.

2. The ionization device (9) according to claim 1, characterized in that - The emitter electrode (15) is electrically connected to the first voltage terminal (13) in a high-impedance manner.

3. The ionization device (9) according to claim 2, characterized in that The emitter electrode (15) is electrically connected to the first voltage terminal (13) via a first ohmic resistor (R1) in a high-resistance manner.

4. The ionization device (9) according to claim 3, characterized in that The first resistor (R1) has a resistance value of at least 5 megohms, at most 20 megohms, and in particular 11 megohms.

5. The ionization device (9) according to any one of the preceding claims, characterized in that - The emitting electrode (15) is electrically connected to the ground portion (M) via a second ohmic resistor (R2) in a high-resistance manner.

6. The ionization device (9) according to claim 5, characterized in that The second resistor (R2) has a resistance value of at least 100 megohms and at most 500 megohms, preferably a resistance value of 400 megohms to 500 megohms.

7. The ionization device (9) according to any one of the preceding claims, characterized in that - The matching electrode (16) is electrically connected to the ground portion (M) in a high-resistance manner via a third ohmic resistor (R3).

8. The ionization device (9) according to claim 7, characterized in that The third resistor (R3) has a resistance value of at least 100 megohms and at most 500 megohms, preferably a resistance value of 100 megohms to 200 megohms.

9. The ionization device (9) according to claim 5 or 6 and claim 7 or 8, characterized in that - the second resistor (R2) and the third resistor (R3) have a total resistance value of 500 megohms to 700 megohms, preferably a total resistance value of 600 megohms, and / or - the second resistor (R2) has a greater resistance value than the third resistor (R3), and / or - A connection point (23) for electrically connecting the emitting electrode (15) and the matching electrode (16) to the ground portion (M) in a high-resistance manner is arranged between the second resistor (R2) and the third resistor (R3).

10. The ionization device (9) according to any one of the preceding claims, characterized in that The voltage generator (12) comprises a high voltage power supply (19) for providing and / or generating a high voltage, and an isolation transformer (20), which is electrically connected to the high voltage power supply (19) on the primary side and has the first voltage terminal (13) and the second voltage terminal (14) on the secondary side.

11. The ionization device (9) according to any one of the preceding claims, characterized in that The voltage generator (12) is designed to generate a high voltage of at least 7 kV and at most 10 kV, in particular to generate a high voltage of 8 kV.

12. An electrostatic filter device (6) for a motor vehicle (1), the electrostatic filter device comprising: - a flow channel (7) for guiding the air flow (5), - a filter element (8), which is arranged in the flow channel (7) so that the air flow (5) flows through the filter element (8), - an ionization device (9) according to any one of the preceding claims, - in, An emitter electrode (15) and a counter electrode (16) are arranged in a flow channel (7) upstream of the filter element (8) with respect to the air flow (5), so that the air flow (5) flows through between the emitter electrode (15) and the counter electrode (16).

13. A motor vehicle (1), comprising: - Vehicle interior space (2), - a fresh air device (3) for supplying fresh air from the surroundings (4) of the vehicle (1) to the vehicle interior (2), - in, The electrostatic filter device (6) according to claim 12 is arranged in the fresh air device (3). - wherein the fresh air flows through the flow channel (7) of the filter device (6) and forms an air flow (5).

14. The motor vehicle (1) according to claim 13, characterized in that - the ground (M) is formed by the electrical vehicle ground (11), and / or The motor vehicle (1) has an air conditioning device (10) for conditioning fresh air, which is arranged in the fresh air device (3) downstream of the filter device (6) with respect to the flow direction of the fresh air.

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