Method for checking a filter unit

Abstract

The invention relates to a method for checking a filter unit (10) which comprises a replaceable filter insert (20) and an electric supply module (22). The replaceable filter insert (20) has at least one polarization element and an electrically insulating filter material which can be polarized via the polarization element by energizing the filter insert (20). An electronic data processing device (30) analyzes the energization of the filter insert (20) by the electric supply module (22) in order to detect a malfunction and / or a functional impairment of the filter unit (10).

Description

[0001] Procedure for testing a filter unit

[0002] The invention relates to a method for testing a filter unit comprising a replaceable filter insert and an electrical supply module, wherein the replaceable filter insert has at least one polarizing element and an electrically insulating filter material that can be polarized by energizing the filter insert via the polarizing element.

[0003] The invention further relates to a filter unit with a replaceable filter insert and an electrical supply module, wherein the replaceable filter insert has at least one electrically conductive polarizing element and an electrically insulating filter material that can be polarized by energizing the filter insert via the polarizing element.

[0004] Gas filters with a replaceable filter insert are known in the art, where the separation efficiency of the gas filter is increased by polarization. Polarization involves applying a high electrical voltage to the filter insert, which generates an electric field in the filter material.

[0005] Due to the fact that the filter element must be changed at regular or irregular intervals, there is always a risk that a person may come into contact with live and / or high-voltage surfaces after accessing the filter element, which poses a significant risk of injury. Furthermore, the contact points for applying voltage to the filter element may be exposed after the filter element has been removed from the gas filter housing. In this case, too, there is a significant risk of injury.

[0006] Furthermore, it is not yet possible to detect whether polarization actually occurs when the filter insert is inserted. If polarization does not occur, for example, due to a defect or incorrect installation of the filter insert, the separation efficiency is significantly reduced, which may require replacing the filter insert. Furthermore, defects in the filter medium of the filter insert, which pose a significant risk of short circuits, are not yet detected.

[0007] Such gas filters can also incorporate an ionizer to further increase their separation efficiency. The operation of the ionizer generates ozone, which must not enter the passenger compartment when the gas filter is used as a cabin filter. An activated carbon layer in the filter reduces the ozone before it enters the cabin. However, it is currently unknown whether a suitable filter insert with activated carbon is actually installed.

[0008] The object of the invention is therefore to increase the safety during operation and maintenance of gas filters with an energized filter insert.

[0009] The object is achieved by a method of the type mentioned at the outset, wherein, within the scope of the method according to the invention, an electronic data processing device evaluates the current supply to the filter insert by the electrical supply module in order to detect a faulty operating state and / or a functional impairment of the filter unit.

[0010] A faulty operating condition can occur, for example, if an unsuitable filter insert is used or the filter insert is not inserted correctly. The filter insert is not inserted correctly, for example, if there is no electrical contact between the filter insert and the filter insert. A faulty operating condition also occurs, for example, if a housing cover of the filter unit is open, in particular if the filter insert is accessible from the outside when the housing cover is open. An unsuitable filter insert can, for example, have an unsuitable design or unsuitable electrical properties or unsuitable filter properties. A functional impairment can occur, for example, if there is no or insufficient polarization.A functional impairment of the filter unit may also occur due to a defect or partial defect in the filter insert, for example due to a damage-related and / or moisture-related short circuit between electrically conductive polarization elements, in particular electrically conductive polarization layers, of the filter insert or between other electrically conductive components of the filter insert. A functional impairment of the filter unit may also occur if the filter insert has reached the end of its service life due to prolonged and / or high dust absorption. In addition, a functional impairment of the filter unit may also occur if the polarization voltage that can be tolerated by the filter insert or one or more polarization elements of the filter insert without flashover or short-circuit is permanently or temporarily reduced beyond a tolerance level.The tolerable polarization voltage can be reduced, for example, by an unintentional ingress of moisture into the filter insert or by an unintentional reduction in the distance between the polarization elements.

[0011] In a preferred embodiment of the method according to the invention, the polarization element is designed as a polarization layer. The polarization layer is preferably a material layer made of an electrically conductive material, in particular an electrically conductive flat material. The polarization layer preferably runs parallel to the filter material, at least in sections. The polarization layer can touch the filter material.

[0012] In another preferred embodiment of the method according to the invention, the replaceable filter insert comprises two electrically conductive polarizing elements, each designed as a polarizing layer, which are separated from one another by an electrically insulating intermediate layer, in particular by the electrically insulating filter material. The electrically insulating intermediate layer or the electrically insulating filter material and the two electrically conductive polarizing layers preferably form a pleated layer composite. An electrical voltage can be applied to the polarizing layers to polarize the filter material by electrically contacting the filter insert with the electrical supply module.

[0013] In a further preferred embodiment of the method according to the invention, the electronic data processing device interrupts the power supply to the filter insert upon detection of a faulty operating state and / or a functional impairment of the filter unit. Alternatively or additionally, the electronic data processing device interrupts the power supply to an ionizer of the filter unit upon detection of a faulty operating state and / or a functional impairment of the filter unit. Preferably, the supply lines of the electrical supply module are de-energized. The interruption of the power supply minimizes the risk of contact-induced electric shock.When the filter unit is used in a vehicle, the data processing device can inform the vehicle control system that there is a faulty operating condition and / or a functional impairment of the filter unit, so that follow-up measures can be initiated on the vehicle side, for example the output of a warning message.

[0014] In another advantageous embodiment of the method according to the invention, the electrical supply module applies a test current to the filter insert to test the electrical contact of the filter insert, and the electronic data processing device evaluates the test current to detect the faulty operating state and / or functional impairment of the filter unit. The filter insert can be contacted by bringing contact points of the filter insert and contact points of the supply module into contact with the electrical supply module. If the electrical contact of the filter insert is lost or faulty, no polarization of the filter material occurs, so that the electronic data processing device can detect a reduced current flow or no current flow in a voltage range. The filter material can be an electret material or can comprise electret material.

[0015] In a further preferred embodiment of the method according to the invention, when evaluating the test current application, the electronic data processing device compares several current-voltage test states that arise during the test current application with filter insert-specific target states or target state ranges. If no filter insert is contacted, or an unsuitable filter insert is contacted, or a suitable filter insert is contacted differently than intended or incorrectly, at least one current-voltage test state does not correspond to a target state or deviates from the target state by a tolerance level, or at least one current-voltage test state lies outside a target state range. Preferably, at least two current-voltage test states are compared with target states or target state ranges.The electronic data processing device can be part of the electrical supply module or a control unit of a vehicle located outside the housing of the filter unit.

[0016] In a further preferred embodiment of the method according to the invention, the electrical supply module provides a plurality of differing electrical test voltages during the test current supply to the filter insert. Furthermore, the electrical current intensities resulting from the respective electrical test voltages are determined. Preferably, the electrical supply module initially provides a first electrical test voltage during the test current supply to the filter insert, and a first electrical current intensity resulting from the first electrical test voltage is determined. Subsequently, a second electrical test voltage is provided, and a second electrical current intensity resulting from the second electrical test voltage is determined. The first electrical test voltage differs from the second electrical test voltage.

[0017] In another embodiment of the method according to the invention, the electronic data processing device checks, when comparing the plurality of current-voltage test states with the filter insert-specific target states or target state ranges, whether the determined electrical currents lie within filter insert-specific target current ranges. Preferably, when comparing the plurality of current-voltage test states with the filter insert-specific target states or target state ranges, the electronic data processing device checks whether the first determined electrical current lies within a first filter insert-specific target current range and the second determined electrical current lies within a second filter insert-specific target current range.

[0018] Furthermore, a method according to the invention is preferred in which the electronic data processing device determines a current-voltage test characteristic and / or a, in particular voltage-dependent, current intensity change value from the multiple current-voltage test states determined during the test current application. To determine the current-voltage test characteristic and / or the current intensity change value, an initial test voltage is first set, which is then gradually increased until the final test voltage is reached.

[0019] A method according to the invention is further preferred in which the electronic data processing device, when comparing the current-voltage test states with the filter insert-specific target states or target state ranges, compares the determined current-voltage test characteristic and / or the determined current intensity change value with a filter insert-specific target characteristic or a filter insert-specific change target value. If the comparison shows that the determined current-voltage test characteristic deviates from the filter insert-specific target characteristic by more than a tolerance level and / or the determined voltage-dependent current intensity change value deviates from the filter insert-specific change target value by more than a tolerance level, the electronic data processing device detects that a faulty operating state and / or a functional impairment of the filter unit exists.In an advantageous development of the method according to the invention, the filter insert-specific target states or target state ranges are stored in a data memory connected to the data processing device. The filter insert-specific target characteristic curve or the filter insert-specific change target value are preferably stored in the data memory connected to the data processing device. Alternatively or additionally, the filter insert-specific target states or target state ranges are determined as part of a calibration routine when the filter insert is new and stored in a data memory connected to the data processing device. The filter insert-specific target characteristic curve or the filter insert-specific change target value are preferably determined as part of the calibration routine when the filter insert is new and stored in the data memory connected to the data processing device.The calibration routine is carried out, for example, as part of the service when changing the filter insert.

[0020] In a further development of the method according to the invention, the filter unit is a component of a vehicle, and the electrical supply module checks the electrical contact of the filter insert by applying a test current to the filter insert when the vehicle is started, preferably each time. The test current can be applied, for example, when the vehicle detects the approach of a driver or passenger. Alternatively or additionally, the test current can be initiated when a user unlocks the vehicle doors from a remote location, for example, via radio. Alternatively or additionally, the test current can be applied during the ignition process.

[0021] Furthermore, a method according to the invention is preferred in which the electronic data processing device detects a current-voltage reference test state that arises during the test current application and, based on the current-voltage reference test state, determines a target state or target state range at a different voltage level and compares the current-voltage test state that arises at the voltage level with the determined target state or target state range. The current-voltage characteristic curve of the filter insert preferably has a linear profile in the tested voltage range. Based on the current-voltage reference test state, the electronic data processing device can determine the linear profile of the current-voltage characteristic curve and calculate a target state or target state range at a different voltage level.The electronic data processing device can also additionally check whether absolute tolerances with high permissible deviations are maintained.

[0022] In another preferred embodiment of the method according to the invention, the electronic data processing device monitors the electrical current intensity that occurs during operation of the filter unit and, in order to detect a faulty operating state and / or functional impairment of the filter unit, continuously checks the resulting electrical current intensity for a characteristic change in the current intensity. In this way, it can be detected whether the contact with the filter insert is interrupted or impaired during operation of the filter unit, for example due to removal of the filter insert. The detection of whether a defined maximum change in current consumption has been exceeded within a time interval is preferably monitored. After a characteristic change in the current intensity has been detected, the faulty electrical contact with the filter insert can be confirmed by applying a test current.When performing the test current application while the filter unit is in operation, if high voltage is used, the high voltage must first be deactivated. Then, for example, the current-voltage characteristic curve can be evaluated.

[0023] In a preferred embodiment of the method according to the invention, the electronic data processing device detects the opening of a housing cover of the filter unit. The electrical supply module can be arranged in the housing cover, wherein the contact with the filter insert is interrupted by the opening of the housing cover. Alternatively, the filter insert can be moved out of a housing body when the housing cover is opened in such a way that a contact located in the housing body is broken. Upon detecting the opening of the housing cover, the electronic data processing device can interrupt the power supply to the filter insert. In other cases, the opening of the housing cover would not lead to an interruption in the power supply to the filter insert.

[0024] In a further preferred embodiment of the method according to the invention, the electronic data processing device detects a short circuit caused by contact between two electrically conductive polarizing elements by evaluating the current supply to the filter insert. In the case of a short circuit, the current increases unevenly and / or excessively while the voltage is increased uniformly. The electronic data processing device detects this uneven and / or excessive current increase.

[0025] In a preferred embodiment of the method according to the invention, the electronic data processing device detects a lack of or unintentional polarization of the filter material by evaluating the current supply to the filter insert. A lack of or unintentional polarization of the filter material leads, on the one hand, to a reduction in filter performance and, on the other hand, to the risk of incorrect contact, which can cause further subsequent defects. If polarization is lacking or unintentional, the filter unit must be inspected or at least the filter insert replaced.

[0026] In another embodiment of the method according to the invention, the electronic data processing device determines the particle load and / or the filter properties of the filter material by evaluating the current supply to the filter insert and / or by evaluating the polarization of the filter material. The particle load of the filter material can relate to the dust load of the filter material. The evaluation of the polarization of the filter material can relate to the evaluation of the polarization behavior of the filter insert. When a specific particle load is reached, a functional impairment can occur. Based on the particle load, the data processing device can, for example, determine the remaining service life of the filter insert.

[0027] In a further preferred embodiment of the method according to the invention, the electronic data processing device determines the remaining service life of the filter insert by evaluating the current supply to the filter insert and / or by evaluating the polarization of the filter material. Based on the current supply and / or the polarization, the remaining filter service life can be determined by the electronic data processing device. The filter insert itself thus functions as a sensor for the filter load or filter service life. This particularly advantageously makes it possible to dispense with additional sensors such as differential pressure sensors. If the remaining service life falls below a limit value, the data processing device can cause an output device to issue a warning, for example a visual or acoustic warning, to change the filter.When a user requests information about the remaining service life of the filter insert, the data processing device can output information about the current particle loading of the filter material and / or the remaining service life, for example in the form of a percentage value.

[0028] Furthermore, a method according to the invention is preferred in which the filter unit has a high-voltage ionizer. The ionizer is preferably powered by the electrical supply module. The electrical supply module, for example, already provides a high voltage, which is tapped by the ionizer without further voltage reduction. The high voltage provided by the supply module is preferably reduced before use for polarization; the voltage reduction can be achieved via a voltage divider.

[0029] A method according to the invention is further advantageous in which, upon detection of an unsuitable filter insert, the electronic data processing device interrupts or at least reduces the voltage supplied to the ionizer by the electrical supply module in order to prevent or at least reduce ozone formation by the ionizer. Preferably, the filter insert and the ionizer are supplied with power via the same supply lines of the electrical supply module. The filter insert can have a voltage divider to reduce the voltage applied to the electrically conductive polarization elements. The supply lines of the electrical supply module can be de-energized upon detection of an unsuitable filter insert. The evaluation of the current-voltage characteristic curve can be used to identify the filter insert.The current supply is only permanently activated when the correct filter insert with a filter insert-specific current-voltage characteristic curve is detected. This can prevent increased ozone emissions, for example, into a vehicle interior.

[0030] Furthermore, a method according to the invention is advantageous in which the electronic data processing device carries out the test current supply to the filter insert in a voltage range which lies below the corona onset voltage of the ionizer. Below the corona onset voltage, only the polarization device of the filter insert, which has an electrical resistance and thus functions as an electrical load, affects the current flow. The electrical resistance of the polarization device is preferably formed by a voltage divider which comprises a resistance path along which a suitable voltage level can be tapped. The polarization device further preferably comprises the at least one polarization element and / or the filter material. In absolute terms, the current flow caused by the resistance can fluctuate greatly; however, below the corona onset voltage it usually has a linear profile.At voltages above the corona threshold voltage, the supply module provides a total current that depends on the polarization resistance and the ionizer. The polarization current increases linearly with increasing voltage. The ionization current increases exponentially with increasing voltage. In another embodiment of the method according to the invention, the electronic data processing device determines the moisture level of the filter insert, in particular by evaluating the current flow to the filter insert and / or by evaluating the polarization of the filter material. The moisture level of the filter insert can be used to detect a moisture-related functional impairment or an impending moisture-related functional impairment of the filter insert.The humidity level can be determined by the electronic data processing device, for example, on the basis of a tolerable polarization voltage of the filter insert.

[0031] Furthermore, a method according to the invention is preferred in which the electronic data processing device initiates a drying process to reduce the moisture in the filter insert. Initiating the drying process can, for example, involve activating a heating device or setting a filter drying mode on a heating device. The heating device can be part of a vehicle's air conditioning system. To initiate the drying process, the electronic data processing device can also evaluate or monitor further signals or measured values, such as the signals or measured values ​​of a humidity sensor, or other data, such as weather data. The weather data can be determined via sensors in the vehicle or retrieved from a database.

[0032] The object underlying the invention is further achieved by a filter unit of the type mentioned at the outset, wherein the filter unit according to the invention has an electronic data processing device which is designed to evaluate the current supply to the filter insert by the electrical supply module in order to detect a faulty operating state and / or a functional impairment of the filter unit.

[0033] The filter unit according to the invention is advantageously further developed in that it is configured to be tested using a method according to one of the embodiments described above. With regard to the advantages and modifications of the filter unit according to the invention, reference is therefore made to the advantages and modifications of the method according to the invention.

[0034] Preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying drawings.

[0035] Fig. 1 shows a filter unit according to the invention with the housing cover open in a schematic perspective view;

[0036] Fig. 2 shows the current-voltage test conditions occurring during a test current application to the filter insert in a current-voltage diagram;

[0037] Fig. 3 shows the current-voltage test conditions occurring during a test current application to the filter insert in a current-voltage diagram; and

[0038] Fig. 4 is a flowchart of a method according to the invention for testing a filter unit.

[0039] Fig. 1 shows a filter unit 10 which is used, for example, in a vehicle for the purpose of interior air filtration.

[0040] The filter unit 10 comprises a housing 12 with a housing body 14 and a housing cover 16 that can be placed onto the housing body 14. The housing cover 16 is removable and serves to close a receiving area 18 of the housing body 14, into which a filter insert 20 is inserted. To insert the filter insert 20, it can be pushed into the receiving area 18 of the housing body 14. To remove the filter insert 20 from the receiving area 18 of the housing body 14, the filter insert 20 can be pulled out of the receiving area 18.

[0041] The filter insert 20 comprises two electrically conductive polarizing elements, each designed as a polarizing layer, which are separated from each other by an electrically insulating filter material. A first polarizing layer is arranged above the electrically insulating filter material. A second polarizing layer is arranged below the electrically insulating filter material. The electrically insulating filter material and the two electrically conductive polarizing layers together form a pleated layered assembly. An electrical voltage U can be applied to the polarizing layers to polarize the filter material.

[0042] For electrically contacting the filter insert 20, the filter unit 10 comprises an electrical supply module 22. In the illustrated embodiment, the electrical supply module 22 is integrated into the housing cover 16. In other embodiments, the electrical supply module 22 can also be arranged beyond the housing cover 16.

[0043] The filter insert 20 has two contact points 24a, 24b on an outer side surface for electrically connecting the filter insert 20 to the electrical supply module 22. The electrical supply module 22 is configured to provide a high voltage that is above the voltage level suitable for polarizing the filter material, so that the voltage present at the contact points 24a, 24b must first be reduced before it is applied to the polarization layers to polarize the filter material. The voltage reduction is achieved via a voltage divider 26. The voltage divider 26 comprises a resistance path 28 along which a suitable voltage level can be tapped.

[0044] The filter unit 10 further comprises a high-voltage ionizer 32. The ionizer 32 is powered by the electrical supply module 22. The high voltage provided by the electrical supply module 22 is matched to the ionization voltage required by the ionizer 32. Thus, both the filter insert 20 and the ionizer 32 can be powered via the electrical supply module 22 and the voltage divider 26, even though the filter insert 20 and the ionizer 32 are operated at different voltages.

[0045] The filter unit 10 further comprises an electronic data processing device 30, which evaluates the power supply to the filter insert 20 by the electrical supply module 22 in order to detect a faulty operating state and / or a functional impairment of the filter unit 10. In the illustrated embodiment, the electronic data processing device 30 is integrated into the housing cover 16. In other embodiments, the data processing device 30 can also be formed beyond the housing cover 16. For example, the data processing device 30 can also be part of a vehicle electronics system.

[0046] The faulty operating state detectable by the data processing device 30 can occur, for example, if an unsuitable filter insert 20 is inserted or if the filter insert 20 is not inserted properly. The filter insert 20 is not inserted properly, for example, if there is no electrical contact between the filter insert 20. A faulty operating state detectable by the data processing device 30 also occurs, for example, if the housing cover 16 of the filter unit 10 is open.

[0047] A functional impairment of the filter unit 10 that can be detected by the data processing device 30 can occur, for example, if no or insufficient polarization occurs.

[0048] When a faulty operating state or a functional impairment of the filter unit 10 is detected, the electronic data processing device 30 interrupts the power supply to the filter insert 20. For example, supply lines of the electrical supply module 22 are de-energized.

[0049] The electrical supply module 22 applies a test current to the filter insert 20 to test the electrical contact of the filter insert 20. Such test currents are shown in Fig. 2 and Fig. 3.

[0050] Fig. 2 shows a current-voltage diagram in which the current I is plotted against the voltage U. Two filter insert-specific target characteristic curves SKL1, SKL2 are entered in the current-voltage diagram. The target characteristic curves SKL1, SKL2 refer to different filter inserts 20. Both target characteristic curves SKL1, SKL2 initially have a linear profile, which then changes to an exponential profile above a corona inception voltage UKES. Below the corona inception voltage UKES, the current flow is exclusively influenced by the polarization device of the filter insert 20, which comprises an electrical resistor and thus acts as an electrical consumer. The electrical resistance of the polarization device is preferably formed by a voltage divider 26, which comprises a resistance path 28, along which a suitable voltage level can be tapped.The polarization device preferably further comprises at least one polarization element and / or the filter material. The gradient of the filter insert-specific target characteristic curve SKL1 or SKL2 depends on the electrical properties of the filter insert 20. At voltages above the corona onset voltage UKES, the supply module 22 provides a total current, which depends on both the resistance for the polarization and the resistance of the ionizer 32. The test current to the filter insert 20 is usually applied below the corona onset voltage U KES of the ionizer 32.

[0051] During the test current application to a first filter insert, the electronic data processing device 30 detects a current-voltage reference test state RPZ1 that occurs during the test current application. In the current-voltage reference test state RPZ1, a reference test voltage URPZ is applied and the current intensity is l RPzi - Starting from the current-voltage reference test state RPZ1, the electronic data processing device 30 determines a target state at a higher voltage level UPZ below the corona inception voltage UKES. Subsequently, the electronic data processing device 30 compares the current-voltage test state PZ1 established at the higher voltage level UPZ with the determined target state. At the higher voltage level UPZ, the current value l PZi In this case, the current l PZion the target characteristic curve SKL1, so that there is no faulty operating state and no functional impairment of the filter unit 10. During the test current application of a replacement filter insert, which was installed during a replacement interval and is referred to below as the "second filter insert", the electronic data processing device 30 records a current-voltage reference test state RPZ2 that arises during the test current application. In the current-voltage reference test state RPZ2, a reference test voltage URPZ is applied and the current intensity is IRPZ2. Based on the current-voltage reference test state RPZ2, the electronic data processing device 30 determines a target state at a higher voltage level UPZ below the corona inception voltage UKES. The electronic data processing device 30 then compares the current-voltage test state PZ2 that arises at the higher voltage level UPZ with the determined target state.At the higher voltage level UPZ, the current value IPZ2 is established. In this case, the current IPZ2 lies on the target characteristic curve SKL2, so there is no faulty operating condition and no functional impairment of the filter unit 10.

[0052] Fig. 3 shows an alternative test current supply to the filter insert 20, with which the electronic data processing device 30 can detect a faulty operating state and a functional impairment of the filter unit 10.

[0053] When evaluating the test current, the electronic data processing device 30 compares several current-voltage test states PZ1, PZ2 that occur during the test current with filter insert-specific target state ranges.

[0054] During the test current application, the electrical supply module 22 provides several different electrical test voltages UPZI , UPZ2 . The electrical currents l that occur at the respective electrical test voltages UPZI , UPZ2 P zi, Ipz2 are then determined by the electronic data processing device 30. The electrical supply module 22 initially provides a first electrical test voltage UPZI during the test current supply to the filter insert 20, and a first electrical current l is established at the first electrical test voltage UPZI. PZi Subsequently, a second electrical test voltage UPZ2 is provided and a second electrical current l is established at the second electrical test voltage UPZ2. PZ2. The second electrical test voltage UPZ2 is higher than the first electrical test voltage UPZI. Both electrical test voltages UPZI and UPZ2 are below the corona inception voltage UKES.

[0055] When comparing the several current-voltage test states PZ1, PZ2 with the filter insert-specific target state ranges, the electronic data processing device 30 checks whether the determined electrical current intensities l P zi, Ipz2 are in the filter insert-specific current intensity target ranges SB1, SB2.

[0056] When comparing the several current-voltage test states PZ1, PZ2 with the filter insert-specific target state ranges, the electronic data processing device 30 checks whether the first determined electrical current intensity l PZiin a first filter-insert-specific current range SB1 and the second determined electrical current IPZ2 is in a second filter-insert-specific current range SB2. This is the case in the test scenario shown, so that the electronic data processing device 30 does not detect any faulty operating state or functional impairment of the filter unit 10.

[0057] Fig. 4 shows the sequence of a test procedure for a filter unit 10. In method step 100, the test current supply routine is first started.

[0058] In step 102, the electronic data processing device 30 first sets the supply voltage to 0 V and checks in step 104 whether the resulting current is 0 A. If the resulting current is not 0 A, the electronic data processing device 30 determines in step 106 a faulty operating state, which is attributable to an electronic defect.

[0059] If the current is 0 A, a first test voltage UPZI is set in step 108. In step 110, it is then checked whether the resulting current l PZ1 lies within a target current range SB1. If the resulting current IPZI lies outside the target current range SB1, the electronic data processing device 30 detects a faulty operating state in step 112.

[0060] If the resulting current l PZiis in the current range SB1, a higher test voltage U PZ 2. In step 116 it is then checked whether the current intensity l PZ 2 is within a current range SB2. If the resulting current l PZ 2 is outside the current intensity target range SB2, a faulty operating state of the filter unit 10 is determined in step 118.

[0061] If the resulting current l PZ 2 is within the current intensity target range SB2, it is checked in step 120 whether the currents l PZ i, l PZ 2 and the test voltages U PZ i, U PZ 2 are in the ratio shown below:

[0062] If the checked current-voltage ratio is not present, the electronic data processing device 30 detects in step 122 a functional impairment of the filter unit 10, namely a missing or faulty polarization.

[0063] If the checked current-voltage ratio is present, the electronic data processing device determines in step 124 that there is no faulty operating state and no functional impairment of the filter unit 10, so that the operation of the filter unit 10 is enabled in step 126.

[0064] If an error condition is detected during the test procedure, the test procedure can be repeated once or several times so that any error correction that has occurred in the meantime can be determined during this repetition routine.

[0065] 10 Filter unit 12 Housing

[0066] 14 Housing body

[0067] 16 Housing cover

[0068] 18 Recording area

[0069] 20 filter inserts

[0070] 22 Supply module

[0071] 24a, 24b Contact points

[0072] 26 voltage dividers

[0073] 28 resistance section

[0074] 30 Data processing device 32 Ionizer

[0075] 100-126 procedural steps

[0076] I current

[0077] IRPZ1 , IRPZ2 current values

[0078] Ipzi , lpZ2 current values ​​and voltage

[0079] UKES corona inception voltage

[0080] URPZ reference test voltage

[0081] UPZ, Upzi, UpZ2 test voltages

[0082] RPZ1 , RPZ2 current-voltage reference test conditions

[0083] PZ1 , PZ2 current-voltage test conditions SKL1 , SKL2 nominal characteristics

[0084] SB1, SB2 current target ranges

Claims

Claims 1. Method for testing a filter unit (10) comprising a replaceable filter insert (20) and an electrical supply module (22), wherein the replaceable filter insert (20) has at least one polarizing element and an electrically insulating filter material that can be polarized by energizing the filter insert (20) via the polarizing element, characterized in that an electronic data processing device (30) evaluates the energization of the filter insert (20) by the electrical supply module (22) in order to detect a faulty operating state and / or a functional impairment of the filter unit (10).

2. Method according to claim 1, characterized in that the polarizing element is designed as a polarizing layer.

3. Method according to claim 1 or 2, characterized in that the replaceable filter insert (20) has two electrically conductive polarizing elements each designed as polarizing layers, which are separated from one another by an electrically insulating intermediate layer, in particular by the electrically insulating filter material.

4. Method according to one of the preceding claims, characterized in that the electronic data processing device (30) causes an interruption of the power supply to the filter insert (20) upon detection of a faulty operating state and / or a functional impairment of the filter unit (10).

5. Method according to one of the preceding claims, characterized in that the electrical supply module (22) carries out a test current supply to the filter insert (20) in order to test the electrical contacting of the filter insert (20), and the electronic data processing device (30) evaluates the test current supply in order to detect the faulty operating state and / or the functional impairment of the filter unit (10).

6. Method according to claim 5, characterized in that the electronic data processing device (30) compares, when evaluating the test current, a plurality of current-voltage test states (PZ1, PZ2) occurring during the test current with filter insert-specific target states or target state ranges.

7. Method according to claim 5 or 6, characterized in that the electrical supply module (22) provides a plurality of different electrical test voltages (II PZI , Upzz) during the test current supply to the filter insert (20) and the electrical current intensities (I PZI , Ipzz) occurring at the respective electrical test voltages (UPZI , UPZZ) are determined.

8. Method according to claim 6, characterized in that the electronic data processing device (30) checks, when comparing the plurality of current-voltage test states (PZ1, PZ2) with the filter insert-specific target states or target state ranges, whether the determined electrical current intensities (IPZI, IPZZ) lie in filter insert-specific target current intensities ranges (SB1, SB2).

9. Method according to one of claims 6 to 8, characterized in that the electronic data processing device (30) from the several current-voltage test states (PZ1, PZ2) determined during the test current application a current-voltage test characteristic and / or a current change value, in particular a voltage-dependent one, is determined.

10. The method according to claim 9, characterized in that the electronic data processing device (30), when comparing the current-voltage test states (PZ1, PZ2) with the filter insert-specific target states or target state ranges, compares the determined current-voltage test characteristic curve and / or the determined current intensity change value with a filter insert-specific target characteristic curve (SKL1, SKL2) or a filter insert-specific change target value.

11. Method according to one of claims 6 to 10, characterized in that the filter insert-specific target states or target state ranges are stored on a data memory connected to the data processing device (30), and / or are determined as part of a calibration routine in the new state of the filter insert (20) and are stored on a data memory connected to the data processing device (30).

12. Method according to one of claims 5 to 11, characterized in that the filter unit (10) is a component of a vehicle and the electrical supply module (22) checks the electrical contacting of the filter insert (20) by means of a test current supply to the filter insert (20) at one, preferably at each, start of the vehicle.

13. Method according to one of claims 5 to 12, characterized in that the electronic data processing device (30) sets a current-voltage reference test state which is established during the test current supply (RPZ1, RPZ2) and, starting from the current-voltage reference test state (RPZ1, RPZ2), a target state or target state range is determined at another voltage level (UPZ) and the current-voltage test state (PZ1, PZ2) that occurs at the voltage level (UPZ) is compared with the determined target state or target state range.

14. Method according to one of the preceding claims, characterized in that the electronic data processing device (30) monitors the electrical current intensity (I) occurring during operation of the filter unit (10) and continuously checks for a characteristic change in the current intensity in order to detect the faulty operating state and / or the functional impairment of the filter unit (10).

15. Method according to one of the preceding claims, characterized in that the electronic data processing device (30) detects an opening of a housing cover (16) of the filter unit (10).

16. Method according to one of the preceding claims, characterized in that the electronic data processing device (30) detects a short circuit caused by contact between the two electrically conductive polarization elements by evaluating the current supply to the filter insert (20).

17. Method according to one of the preceding claims, characterized in that the electronic data processing device (30) detects a lack of or unintentional polarization of the filter material by evaluating the current supply to the filter insert (20).

18. Method according to one of the preceding claims, characterized in that the electronic data processing device (30) determines the particle loading and / or the filter properties of the filter material by evaluating the current supply to the filter insert (20) and / or by evaluating the polarization of the filter material.

19. Method according to one of the preceding claims, characterized in that the electronic data processing device (30) determines a remaining service life of the filter insert (20) by evaluating the current supply to the filter insert (20) and / or by evaluating the polarization of the filter material.

20. Method according to one of the preceding claims, characterized in that the filter unit (10) has an ionizer (32) operated with high voltage, wherein the ionizer (32) is preferably supplied with current from the electrical supply module (22).

21. Method according to claim 20, characterized in that the electronic data processing device (30), upon detection of an unsuitable filter insert (20), interrupts or at least reduces the voltage supplied to the ionizer (32) by the electrical supply module (22) in order to prevent or at least reduce ozone formation by the ionizer (32).

22. Method according to claim 20 or 21, characterized in that the electronic data processing device (30) carries out the test current supply to the filter insert (20) in a voltage range which is below the corona inception voltage (UKES) of the ionizer (32).

23. Method according to one of the preceding claims, characterized in that the electronic data processing device (30) determines a moisture state of the filter insert (20), in particular by evaluating the current supply to the filter insert (20) and / or by evaluating the polarization of the filter material.

24. Method according to one of the preceding claims, characterized in that the electronic data processing device (30) initiates a drying process to reduce the moisture in the filter insert (20).

25. A filter unit (10) comprising a replaceable filter insert (20); and an electrical supply module (22); wherein the replaceable filter insert (20) has at least one electrically conductive polarizing element and an electrically insulating filter material that can be polarized by energizing the filter insert (20) via the polarizing element, characterized by an electronic data processing device (30) configured to evaluate the energization of the filter insert (20) by the electrical supply module (22) in order to detect a faulty operating state and / or a functional impairment of the filter unit (10).

26. Filter unit (10) according to claim 25, characterized in that the filter unit (10) is adapted to be tested by means of a method according to one of claims 1 to 24.

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