Filtering device for a motor vehicle and method for operating the filtering device

Abstract

The invention relates to a filter device having a stepped filter composed of individual filter elements arranged in series for a fluid, two flow paths for an air flow extending through the stepped filter, wherein a first flow path extends through at least two of the individual filter elements such that the individual filter elements can be flowed through by air, wherein a second flow path extends through a single individual filter element such that the single individual filter element can be flowed through by air, an air flap arranged upstream or downstream of the stepped filter, by means of which a first air flow of the air in the air flows and / or a second air flow of the air in the air flows is guided through the stepped filter along the first flow path or along the second flow path. The invention also relates to a method for operating such a filter device.

Description

TECHNICAL FIELD

[0001] The invention relates to a filter arrangement for a motor vehicle according to the subject matter of claim 1. The invention also relates to a method of operating the filter arrangement. BACKGROUND

[0002] Filter arrangements are used for filtering air and supplying this air downstream in the exhaust air flow of the filter arrangement with a predetermined air quality, for example on the user side. In order to internally act on the air flow flowing through these arrangements, the possibilities offered by established filter arrangements are relatively few, and they are therefore rather inflexible in this respect. This can result in the requirements for the air quality of the exhaust air flow, for example on the user side, not being adequately met. SUMMARY

[0003] It is an object of the invention to provide or indicate an improved or at least different embodiment of a filter arrangement for a motor vehicle. It can also be an object to propose a method of operating such a filter arrangement.

[0004] The object is achieved in the invention, inter alia, by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims and the description.

[0005] The basic idea of the invention is to configure a filter arrangement for a motor vehicle in a flexible manner by means of a plurality of adjustable air flaps, taking into account the possibilities of being able to internally act on the air flow flowing through.

[0006] To this end, a filter device of a motor vehicle, in particular of an air conditioning system of a motor vehicle, is provided, which is equipped with a stepped filter, which consists of individual filter elements arranged in fluid series with respect to one another for the stepwise filtering of air. Two individual flow paths for the air flow of air extend through the stepped filter, wherein one of the two flow paths, the first flow path, extends through at least two of the individual filter elements, so that these individual filter elements can be flowed through by air. On the other hand, the other of the two flow paths, the second flow path, extends through a number of individual filter elements, so that this smaller number of individual filter elements can also be flowed through by air, the number of individual filter elements through which the second flow path extends being at least reduced by a single individual filter element compared to the number of individual filter elements through which the first flow path extends. Advantageously, therefore, the second flow path always extends through fewer individual filter elements than the first flow path. In other words, the flow paths can thus be realized by different stages of the stepped filter. The filter device also has air flaps arranged in the filter device, which can in particular be adjusted in a rotary or translatory manner, by means of which the first air flow of air of the air flows and / or the second air flow of air of the air flows is guided through or can be guided through the stepped filter along the first flow path or along the second flow path.

[0007] By the at least partial fluid series connection of the individual filter elements of the stepped filter, it is achieved that air can flow through the stepped filter along the first flow path and, in doing so, always through more individual filter elements than air flowing through the stepped filter along the second flow path. The stepped filter can therefore provide a fine filter stage type or a strong filter stage type of air along the first flow path and a coarse filter stage of air or a filter stage which is at least degraded in its air filtering performance compared to the fine filter stage along the second flow path, wherein the fine filter stage achieves a stronger purification of the air flowing there through compared to the coarse filter stage of air (coarse filtering). Air flow guidance of the two air flows by means of the air flaps provides the possibility of passing one and / or the other of the two air flows through the fine filter stage of the stepped filter or through the coarse filter stage of the stepped filter, so that air is optionally loaded to the fine filter stage or the coarse filter stage. Overall, the advantage is that the requirements of the user side for the air quality can be flexibly realized.

[0008] The term "air quality" advantageously denotes here a difference which can be detected in a metered manner or at least determined by sensory perception, between a predetermined ideal air quality value which can be verified in a metered manner with reference to ideal air and an actually measurable air quality value of the air flowing in particular within the filter device.

[0009] It is advantageous if the first air flow is formed by fresh air which flows into the filter device through a fresh air inlet of the filter device and the second air flow is formed by recirculation air which flows into the filter device through a recirculation air inlet of the filter device. The filter device can thus be flowed through alternatively by fresh air or recirculation air, so that the filter device can be operated in recirculation air or in fresh air. It is conceivable that the fresh air is taken for example from the environment of the motor vehicle and / or the recirculation air is taken from the passenger compartment of the motor vehicle. The adjustable air flap and the cascade filter create the advantageous possibility here of being able to react flexibly to the air quality difference between fresh air and / or recirculation air by guiding the fresh air through the cascade filter along the first flow path or the second flow path in fresh air operation or by guiding the recirculation air through the cascade filter along the first flow path or the second flow path in recirculation air operation. The current air quality can thus be maintained virtually unchanged or a predetermined air quality is quickly produced when switching back and forth between recirculation air operation and fresh air operation.

[0010] It can furthermore be advantageous if the filter device has at least one air quality sensor for detecting the air quality value of the air flowing through the filter device. It is at least conceivable here that one or more C02 air quality sensors or one or more particulate matter air quality sensors are involved. The advantage is that the air quality value of the air flowing through the filter device can be detected in a metered manner. It is advantageous if the at least one air quality sensor involves an internal air quality sensor which is arranged directly in the air flow of one and / or the other air, so that the air quality value of the flowing air can be detected directly. It is advantageous if the arrangement of the air quality sensor is located for example upstream and / or downstream of the cascade filter. The advantage is that changes in the air quality value of the air can be detected quickly and can be reacted to accordingly.

[0011] Furthermore, it is advantageous if the first flow path extends through exactly two or more individual filter elements, while the second flow path extends through exactly a single individual filter element. By increasing the number of individual filter elements through which the first flow path and / or the second flow path extends, i.e. in particular by increasing the number of individual filter elements through which the air flows, an improved purification or a corresponding filtration of the air flowing through the stepped filter can essentially be achieved. By the (minimum) number of individual filter elements for the first flow path and the second flow path described above, an advantageous preferred configuration of the filter device is proposed, in which the corresponding filter device can be realized in a relatively economic, compact and lightweight manner.

[0012] It is worth mentioning that each of the individual filter elements can be manufactured from a filter material, for example with pleats, and can advantageously be realized in the shape of a cuboid. Thus, by means of the individual filter elements, a sufficient filtration of the air and / or a relatively easy installation can be ensured, or a filter change of the individual filter elements can be easily and quickly realized, respectively.

[0013] Furthermore, it is advantageous if the filter device has three individually adjustable air flaps. Thus, the air flow through the filter device can be guided in a relatively flexible manner. It is conceivable that, depending on the actual air flow conditions encountered in the filter device, more or fewer air flaps and / or additional rigid air conducting elements are used for guiding the air. For example, in order to adjust the air flaps, electric actuators can be used.

[0014] When the filter device has three air flaps, it is advantageous if one of the three air flaps is individually adjustable and the other two of the air flaps are mechanically coupled to each other by a coupling and can be jointly adjusted. Thus, the air flow through the filter device can also be guided in a relatively flexible manner. However, the number of actuators required to adjust the air flaps can be reduced, so that the filter device can be realized in a relatively economic and lightweight manner.

[0015] Furthermore, it is advantageous if the three air flaps are realized by a fresh air flap, a bypass air flap and a recirculation air flap. Here, it can be provided that the fresh air flap is adjustable between a first closed position, which blocks the fresh air inlet of the filter device, a second closed position, by which the first flow path is blocked for a first air flow of fresh air flowing in from the fresh air inlet of the filter device and for a second air flow of recirculation air flowing in from the recirculation air inlet of the filter device, and a plurality of open positions, by which the first air flow of fresh air flowing in from the fresh air inlet and the second air flow of recirculation air flowing in from the recirculation air inlet are respectively unobstructed along the first flow path. Furthermore, it can be provided that the bypass air flap is adjustable between a first closed position, by which the second flow path is blocked for the first air flow of fresh air flowing in from the fresh air inlet and for the second air flow of recirculation air flowing in from the recirculation air inlet, however, the first flow path is unobstructed for the first air flow of fresh air flowing in from the fresh air inlet and / or for the second air flow of recirculation air flowing in from the recirculation air inlet, a second closed position, by which the second flow path is blocked for the first air flow of fresh air flowing in from the fresh air inlet, the second flow path is unobstructed for the second air flow of recirculation air flowing in from the recirculation air inlet, and by which the first flow path is blocked for the second air flow of recirculation air flowing in from the recirculation air inlet, and a plurality of open positions, by which the first air flow of fresh air flowing in from the fresh air inlet is unobstructed along the second flow path and the second air flow of recirculation air flowing in from the recirculation air inlet is unobstructed along the first flow path, respectively. The recirculation air flap can be adjustable between a closed position, by which the second air flow of recirculation air flowing in from the recirculation air inlet is blocked, and a plurality of open positions, by which the second air flow of recirculation air flowing in from the recirculation air inlet is unobstructed along the first flow path or along the second flow path, respectively. Thus, a configuration of the filter device is indicated, in which the air flows of recirculation air and fresh air are realized and the air flaps are realized by three air flaps, which can be adjusted back and forth between a closed position and an open position. Thereby, a relatively flexible guidance of the air flows can be realized inside the filter device.

[0016] A further basic idea of the present application is to indicate a method for operating a filter device according to the above description, which can be realized in addition to or instead of the above-mentioned basic ideas. The proposed method is characterized in that the operating modes A) to D) to be performed have steps which are respectively optionally executed in sequence or in any desired order:

[0017] A) operating the filter device with coarse filtration under fresh air operation, with the following steps:

[0018] 1 ) providing a first air flow of fresh air flowing from a fresh air inlet of the filtration device,

[0019] 2) adjusting a fresh air petal of the air petals to its second closed position, whereby the first flow path is blocked for the first air flow of fresh air flowing from the fresh air inlet,

[0020] 3) adjusting a bypass air petal of the air petals to one of its open positions, whereby the second flow path is unobstructed for the first air flow of fresh air flowing from the fresh air inlet,

[0021] 4) adjusting a recirculation air petal of the air petals to its closed position, whereby the second air flow of recirculation air flowing from a recirculation air inlet of the filtration device is blocked,

[0022] such that in total the second air flow of recirculation air flowing from the recirculation air inlet is completely blocked by the recirculation air petal; the first flow path is completely blocked by the fresh air petal for the first air flow of fresh air flowing from the fresh air inlet, and the second flow path is unobstructed for the first air flow of fresh air flowing from the fresh air inlet through the fresh air petal and the bypass air petal, such that the first air flow of fresh air flows through the stepped filter along the second flow path, and / or

[0023] B) operating the filtration device in a fine filtration mode under fresh air operation, by the following steps:

[0024] 1 ) providing a first air flow of fresh air flowing from a fresh air inlet of the filtration device,

[0025] 2) adjusting a fresh air petal of the air petals to one of its open positions, whereby the first air flow of fresh air flowing from the fresh air inlet is unobstructed,

[0026] 3) adjusting a bypass air petal of the air petals to its second closed position, whereby the second flow path is blocked for the first air flow of fresh air flowing from the fresh air inlet,

[0027] 4) adjusting a recirculation air petal of the air petals to its closed position, whereby the second air flow of recirculation air flowing from a recirculation air inlet of the filtration device is blocked,

[0028] such that in total the second air flow of recirculation air flowing from the recirculation air inlet is completely blocked by the recirculation air petal; the second flow path is blocked by the bypass air petal for the first air flow of fresh air flowing from the fresh air inlet; and the first flow path is unobstructed for the first air flow of fresh air flowing from the fresh air inlet through the fresh air petal, such that the first air flow of fresh air flows through the stepped filter along the first flow path, and / or

[0029] C) operating the filter arrangement in a coarse filtration mode under recirculation air operation, by the following steps:

[0030] 1 ) providing a second air stream of recirculation air flowing from the recirculation air inlet of the filter arrangement,

[0031] 2) adjusting the fresh air flap of the air flaps to its first closed position to block the fresh air inlet of the filter arrangement,

[0032] 3) adjusting the bypass air flap of the air flaps to its second closed position, whereby the first flow path is blocked for the second air stream of recirculation air flowing from the recirculation air inlet, whereas the second flow path is unblocked for the second air stream of recirculation air flowing from the recirculation air inlet,

[0033] 4) adjusting the recirculation air flap of the air flaps to one of its open positions, whereby the second air stream of recirculation air flowing from the recirculation air inlet is unblocked along the second flow path, respectively,

[0034] such that, in total, the first air stream of fresh air, optionally flowing from the fresh air inlet of the filter arrangement, is completely blocked, the first flow path is completely blocked by the bypass air flap for the second air stream of recirculation air flowing from the recirculation air inlet; and the second flow path is unblocked for the second air stream of recirculation air flowing from the recirculation air inlet, through the recirculation air flap and the bypass air flap, such that the second air stream of recirculation air flows along the second flow path through the stepped filter, and / or

[0035] D) operating the filter arrangement in a fine filtration mode under recirculation air operation, by the following steps:

[0036] 1 ) providing a second air stream of recirculation air flowing from the recirculation air inlet of the filter arrangement,

[0037] 2) adjusting the fresh air flap of the air flaps to its first closed position to block the fresh air inlet of the filter arrangement,

[0038] 3) adjusting the bypass air flap of the air flaps to its first closed position, whereby the second flow path is blocked for the second air stream of recirculation air flowing from the recirculation air inlet, whereas the first flow path is unblocked for the second air stream of recirculation air flowing from the recirculation air inlet,

[0039] 4) adjusting the recirculation air flap of the air flaps to one of its open positions, whereby the second air stream of recirculation air flowing from the recirculation air inlet is unblocked along the first flow path, respectively,

[0040] such that, in general, a first air flow of fresh air, optionally flowing in from the fresh air inlet of the filter device, is completely blocked, for a second air flow of recirculated air flowing in from the recirculated air inlet, the second flow path is completely blocked by the bypass air flap, and for a second air flow of recirculated air flowing in from the recirculated air inlet, through the recirculated air flap, the bypass air flap and the fresh air flap, the first flow path is unobstructed, such that the second air flow of recirculated air flows along the first flow path through the stepped filter.

[0041] Thus, in general, an advantageous method for operating a filter device is proposed, wherein within the method the filter device can be operated alternatively in a fresh air mode (see operating modes A) and B)) or in a recirculated air mode (see operating modes C) and D)). According to the method, it is further provided that in the fresh air mode and in the recirculated air mode a selection between a fine filtering operation and a coarse filtering operation is possible. Thus, at the user side it is possible to provide a waste air flow from fresh air or recirculated air in a high intensity filtering manner or in a low intensity filtering manner.

[0042] In summary, it is still to be noted that the present invention preferably relates to a filter device having a stepped filter consisting of individual filter elements arranged in series for the flow of air, two flow paths of the air flow extending through the filter elements, wherein a first flow path extends through at least two of the individual filter elements such that the elements can be flowed through by air, wherein a second flow path extends through a single individual filter element such that the single individual filter element can be flowed through by air, an air flap arranged upstream or downstream of the stepped filter by means of which a first air flow of the air of the air flow and / or a second air flow of the air of the air flow is guided through the stepped filter along the first flow path or along the second flow path. The present invention also advantageously relates to a method of operating such a filter device.

[0043] Further important features and advantages of the present invention will become apparent from the dependent claims, the drawings and the description of the related drawings with reference to the drawings.

[0044] It is to be understood that the features mentioned above and those to be further explained below can be used not only in the respectively specified combinations, but also in other combinations or in isolation without departing from the scope of the present invention. BRIEF DESCRIPTION OF DRAWINGS

[0045] Preferred exemplary embodiments of the present invention are shown in the drawings and are explained in more detail in the following description, in which the same reference notations denote the same or similar or functionally identical parts.

[0046] are shown schematically, respectively:

[0047] Figure 1 A cross-sectional view of a filter device according to the present application is shown according to one preferred example embodiment,

[0048] Figure 2 A cross-sectional view of a filter device according to the present application is shown according to one preferred example embodiment, Figure 1 wherein the filter device is operated in fresh air operation, performing a coarse filtration of the fresh air flowing through,

[0049] Figure 3 A cross-sectional view of a filter device according to the present application is shown according to one preferred example embodiment, Figure 1 wherein the filter device is operated in fresh air operation, performing a fine filtration of the fresh air flowing through,

[0050] Figure 4 A cross-sectional view of a filter device according to the present application is shown according to one preferred example embodiment, Figure 1 wherein the filter device is operated in recirculation air operation, performing a coarse filtration of the recirculation air flowing through, and finally

[0051] Figure 5 A cross-sectional view of a filter device according to the present application is shown according to one preferred example embodiment, Figure 1 wherein the filter device is operated in recirculation air operation, performing a fine filtration of the recirculation air flowing through. DETAILED DESCRIPTION

[0052] Figures 1 to 5 A preferred example embodiment of a filter device is shown, which is generally designated with the reference numeral 1, for filtering air of a motor vehicle (not depicted). By way of example, the filter device 1 can be integrated or retrofitted in an air conditioning system of the motor vehicle.

[0053] With reference to Figure 1 , it is noted that the filter device 1 has a housing 2, which delimits a mounting space 4. The housing 2 has two separate air inlets, which are spaced apart from one another and open into the mounting space 4, wherein the upwardly open inlet serves for the inflow of fresh air, so that it is designated here as fresh air inlet 29 of the filter device 1, and the other opening, which opens laterally, serves for the inflow of recirculation air and is therefore designated as recirculation air inlet 30 of the filter device 1. Thereby, in the operation of the filter device 1, a first air flow 37 (see Figure 2 and Figure 3 ) of fresh air, essentially from the fresh air inlet 29, and a second air flow 38 (see Figure 4 and Figure 5 ) of recirculation air, from the recirculation air inlet 30, can flow into the filter device 1. It is provided here that the filter device 1 can optionally be operated in recirculation air operation or fresh air operation, so that either the first air flow 37 (seeFigure 2 and Figure 3 ) either a second air stream 38 (see Figure 4 and Figure 5 ) flows into the filter device 1.

[0054] Furthermore, Figures 1 to 5 The filter device 1 in the installation space 4 has a multi-stage cascade filter 32 which is fixed to the housing 2 from the inside, where the cascade filter is assembled from two separate filter elements 33, 34 which are arranged in fluidic series with respect to one another for the stepwise filtering of the air. As an example, two separate flow paths 35, 36 for the air streams 37, 38 extend through the cascade filter 32, wherein a first flow path 35 (indicated by a dotted line in Figures 1 to 4 ) of the two flow paths 35, 36 respectively extends through both separate filter elements 33, 34 such that these separate filter elements can be flown through by the air. On the other hand, the other flow path, i.e. the second flow path 36 (indicated by a double dotted line in Figures 1 to 4 ) of the two flow paths 35, 36 respectively extends only through a single separate filter element 33 such that the number of separate filter elements 33, 34 through which the second flow path 36 extends is reduced compared to the first flow path 35. Thereby, the cascade filter 32 can implement a fine filter stage type or a strong filter stage type of the air along the first flow path 35 and a coarse filter stage filtering of the air along the second flow path 36, wherein the fine filter stage implements a stronger purification of the air flowing there through (fine filtering) compared to the coarse filter stage (coarse filtering) of the air flowing there through.

[0055] Furthermore, the filter device 1 has three air flaps 3, 10, 17 which are arranged upstream of the cascade filter 32 (or downstream of the cascade filter 32 if applicable) in the installation space 4 of the filter device 1 and are adjustable, by means of which the first air stream 37 of fresh air of the air streams 37, 38 and / or the second air stream 38 of recirculated air of the air streams 37, 38 can be guided through the cascade filter 32 along the first flow path 35 or alternatively along the second flow path 36. The adjustable air flaps 3, 10, 17 thus enable an air stream guidance by which the filter device 1 can first optionally be operated in fresh air operation or in recirculated air operation. Furthermore, the air flaps 3, 10, 17 provide the option of additionally switching back and forth between fine filtering of the air flowing through and coarse filtering of the air flowing through within the respective operating type. Overall, the advantage is that the requirements of the user side for the air quality can be flexibly implemented.

[0056] Purely by way of example, the air flaps 3, 10, 17 are implemented by a fresh air flap 3, a bypass air flap 10 and a recirculation air flap 17. Here, this can involve rotationally adjustable flaps, or involve sliders which are adjustable in a translational manner.

[0057] In Figures 2 to 5 , a method for operating the filter device 1 is shown. The method is distinguished by four different operating modes A) to D), which each comprise steps to be executed in sequence or in any desired order, which are described below with reference to Figure 1 . Figures 2 to 4

[0058] In Figure 2 , the operating mode A of the method is shown, in which the filter device 1 is operated with coarse filtration under fresh air operation. To this end, a first air flow 37 of fresh air flowing in from the fresh air inlet 29 is first provided, and the air flaps 3, 10, 17 are adjusted as follows: the fresh air flap 3 is adjusted to the second closed position 7, whereby the first flow path 35 is blocked for the first air flow 37 of fresh air flowing in from the fresh air inlet 29. The bypass air flap 10 is adjusted to one of the plurality of conceivable open positions 15, whereby the second flow path 36 is open for the first air flow 37 of fresh air flowing in from the fresh air inlet 29. The recirculation air flap 17 is adjusted to the closed position 20, whereby the second air flow 38 of recirculation air optionally flowing in from the recirculation air inlet 30 is completely blocked. Thus, under the operating mode A of the method, it is generally possible to achieve that the second air flow 38 of recirculation air optionally flowing in from the recirculation air inlet 30 is completely blocked by the recirculation air flap 17, that the first flow path 35 is completely blocked for the first air flow 37 of fresh air flowing in from the fresh air inlet 29 by the fresh air flap 3, and that the second flow path 36 is open for the first air flow 37 of fresh air flowing in from the fresh air inlet 29 through the fresh air flap 3 and the bypass air flap 10. The effect of this is that the first air flow 37 of fresh air flows along the second flow path 36 through the stepped filter 32, wherein or by which the coarse filtration under fresh air operation is achieved.

[0059] In Figure 3 ​In the method according to the application, the operation mode B of the method is shown, in which the filter device 1 is operated with fine filtration under fresh air operation. To this end, firstly the first air stream 37 of fresh air flowing in from the fresh air inlet 29 of the filter device 1 is provided again, and the air flaps 3, 10, 17 are adjusted as follows: the fresh air flap 3 is adjusted to one of its open positions 8, whereby the first air stream 37 of fresh air flowing in from the fresh air inlet 29 is unobstructed. The bypass air flap 10 is adjusted to the second closed position 14, whereby the second flow path 36 is blocked for the first air stream 37 of fresh air flowing in from the fresh air inlet 29. Furthermore, the recirculation air flap 17 is adjusted to the closed position 20, whereby the second air stream 38 of recirculation air optionally flowing in from the recirculation air inlet 30 of the filter device 1 is blocked. Thus, under the operation mode B of the method, it is generally possible to achieve that firstly the second air stream 38 of recirculation air optionally flowing in from the recirculation air inlet 30 is completely blocked by the recirculation air flap 17, that the second flow path 36 is blocked for the first air stream 37 of fresh air flowing in from the fresh air inlet 29 by the bypass air flap 10, and that the first flow path 35 is unobstructed for the first air stream 37 of fresh air flowing in from the fresh air inlet 29 through the fresh air flap 3. Thus, the first air stream 37 of fresh air can flow along the first flow path 35 through the stepped filter 32, whereby the fine filtration under fresh air operation is achieved.

[0060] In Figure 4The diagram illustrates the operation mode C of the method, in which the filter device 1 operates with coarse filtration under circulating air operation. For this purpose, a second airflow 38 of circulating air is first provided from the circulating air inlet 30 of the filter device 1, and the air flaps 3, 10, and 17 are adjusted as follows: the fresh air flap 3 is adjusted to the first closed position 6, where the fresh air inlet 29 of the filter device 1 is completely blocked, thus blocking the optional first airflow 27 of fresh air. Furthermore, the bypass air flap 10 is adjusted to the second closed position 14, thereby blocking the first flow path 35 for the second airflow 38 of circulating air from the circulating air inlet 30, while the second flow path 36 is unobstructed. Additionally, the circulating air flap 17 is adjusted to one of its open positions 22, thereby correspondingly allowing the second airflow 38 of circulating air from the circulating air inlet 30 to flow along the second flow path 36. Therefore, in operating mode C of the method, it is generally possible to achieve the following: Firstly, the first airflow 37 of fresh air entering from the fresh air inlet 29 of the filter device 1 is optionally completely blocked; for the second airflow 38 of recirculated air entering from the recirculated air inlet 30, the first flow path 35 is completely blocked by the bypass air valve 10; and for the second airflow 38 of recirculated air entering from the recirculated air inlet 30 and passing through the recirculated air valve 17 and the bypass air valve 10, the second flow path 36 is unobstructed. Therefore, the second airflow 38 of recirculated air can flow along the second flow path 36 through the stepped filter 32, thereby achieving the coarse filtration under recirculated air operation.

[0061] Finally, Figure 5In the middle, an operating mode D of the method is shown, in which the filter device 1 is operated with fine filtering under recirculation air operation. To this end, firstly the second air flow 38 of the recirculation air flowing in from the recirculation air inlet 30 of the filter device 1 is provided again, and then the air flaps 3, 10, 17 are adjusted as follows: the fresh air flap 3 is adjusted to the first closed position 6, in which the fresh air inlet 29 of the filter device 1 is blocked for the first air flow 37 of fresh air. The bypass air flap 10 is then adjusted to the first closed position 13, whereby the second flow path 36 is blocked for the second air flow 38 of recirculation air flowing in from the recirculation air inlet 30, whereas the first flow path 35 is open for the second air flow 38 of recirculation air flowing in from the recirculation air inlet 30. Furthermore, the recirculation air flap 17 is adjusted to the open position 22, whereby the first flow path 35 is open for the second air flow 38 of recirculation air flowing in from the recirculation air inlet 30. Thus, under the operating mode D of the method, it is possible overall to achieve that firstly the first air flow 37 of fresh air optionally flowing in from the fresh air inlet 29 is completely blocked, that the second flow path 36 is completely blocked by the bypass air flap 10 for the second air flow 38 of recirculation air flowing in from the recirculation air inlet 30, and that the first flow path 35 is open for the second air flow 38 of recirculation air flowing in from the recirculation air inlet 30 through the recirculation air flap 17, the bypass air flap 10 and the fresh air flap 3. The advantage of this is that the second air flow 38 of recirculation air flows along the first flow path 35 through the stepped filter 32, whereby the fine filtering under recirculation air operation is achieved.

Claims

1. A filter device (1) for a motor vehicle, having - a stepped filter (32) composed of individual filter elements (33, 34) arranged in fluid series with respect to one another for the stepwise filtration of air, two flow paths (35, 36) for an air flow (37, 38) extending through the stepped filter, wherein a first flow path (35) of the two flow paths (35, 36) extends through at least two individual filter elements (33, 34) of the individual filter elements (33, 34) such that these individual filter elements (33, 34) can be flowed through by air, wherein a second flow path (36) of the two flow paths (35, 36) extends through a number of individual filter elements (33, 34) such that these individual filter elements (33, 34) can be flowed through by air, the number of individual filter elements (33, 34) through which the second flow path (36) extends being at least reduced by a single individual filter element (33, 34) compared to the number of individual filter elements (33, 34) through which the first flow path (35) extends, - an adjustable air flap (3, 10, 17) arranged upstream of the stepped filter (32) in the filter device (1), by means of which a first air flow (37) of air in the air flow (37, 38) and / or a second air flow (38) of air in the air flow (37, 38) is / is can be guided through the stepped filter (32) along the first flow path (35) or along the second flow path (36), wherein the first air flow (37) being formed from fresh air which flows into the filter device (1) through a fresh air inlet (29) of the filter device (1), and the second air flow (38) being formed from recirculation air which flows into the filter device (1) through a recirculation air inlet (30) of the filter device (1).

2. The filter device (1) according to claim 1, characterized in that the filter device (1) has at least one air quality sensor for detecting an air quality value of the air flowing through the filter device (1).

3. The filter device (1) according to claim 1 or 2, characterized in that the first flow path (35) extends through exactly two or more individual filter elements (33, 34), and the second flow path (36) extends through exactly a single individual filter element (34).

4. The filter device (1) according to claim 1 or 2, characterized in that the filter device (1) has three individually adjustable air flaps (3, 10, 17).

5. The filter device (1) according to claim 1 or 2, characterized in that the filter device (1) has three air flaps (3, 10, 17), one of which (3, 10, 17) is individually adjustable, and the other air flaps (3, 10, 17) can be jointly adjusted by a coupling.

6. The filter device (1) according to claim 1 or 2, characterized in that the air flap (3, 10, 17) is realized by a fresh air flap (3), a bypass air flap (10) and a recirculation air flap (17).

7. The filter device (1) according to claim 6, characterized in that the fresh air flap (3) is adjustable between a first closed position (6), which blocks the fresh air inlet (29) of the filter device (1), and a second closed position (7), whereby the first flow path (35) is blocked for a first air flow (37) of fresh air flowing in from the fresh air inlet (29) of the filter device (1) and for a second air flow (38) of recirculation air flowing in from the recirculation air inlet (30) of the filter device (1), and a plurality of open positions (8), whereby the first air flow (37) of fresh air flowing in from the fresh air inlet (29) and the second air flow (38) of recirculation air flowing in from the recirculation air inlet (30) are respectively unblocked along the first flow path (35), and / or the bypass air flap (10) is adjustable between a first closed position (13), whereby the second flow path (36) is blocked for the first air flow (37) of fresh air flowing in from the fresh air inlet (29) and for the second air flow (38) of recirculation air flowing in from the recirculation air inlet (30), whereas the first flow path (35) is unblocked for the first air flow (37) of fresh air flowing in from the fresh air inlet (29) and / or for the second air flow (38) of recirculation air flowing in from the recirculation air inlet (30), and a second closed position (14), whereby the second flow path (36) is blocked for the first air flow (37) of fresh air flowing in from the fresh air inlet (29), the second flow path (36) is unblocked for the second air flow (38) of recirculation air flowing in from the recirculation air inlet (30), and the first flow path (35) is blocked for the second air flow (38) of recirculation air flowing in from the recirculation air inlet (30), and a plurality of open positions (15), whereby the first air flow (37) of fresh air flowing in from the fresh air inlet (29) is respectively unblocked along the second flow path (36) and the second air flow (38) of recirculation air flowing in from the recirculation air inlet (30) is respectively unblocked along the first flow path (35), and / or the recirculation air flap (17) is adjustable between a closed position (20), whereby the second air flow (38) of recirculation air flowing in from the recirculation air inlet (30) is blocked, and a plurality of open positions (22), whereby the second air flow (38) of recirculation air flowing in from the recirculation air inlet (30) is respectively unblocked along the first flow path (35) or along the second flow path (36).

8. A method for operating a filter device (1) according to one of claims 1 to 7, characterized in that The operational modes A) to D) to be executed have steps which are executed in sequence or in any desired order, respectively: A) Operating the filter device (1) with coarse filtration under fresh air operation, the steps being as follows: 1) Providing a first air flow (37) of fresh air flowing in from a fresh air inlet (29) of the filter device (1), 2) Adjusting a fresh air flap (3) of the air flaps (3, 10, 17) to its second closed position (7), whereby, for the first air flow (37) of fresh air flowing in from the fresh air inlet (29), the first flow path (35) is blocked, 3) Adjusting a bypass air flap (10) of the air flaps (3, 10, 17) to one of its open positions (15), whereby, for the first air flow (37) of fresh air flowing in from the fresh air inlet (29), the second flow path (36) is unobstructed, 4) Adjusting a recirculation air flap (17) of the air flaps (3, 10, 17) to its closed position (20), whereby a second air flow (38) of recirculation air flowing in from a recirculation air inlet (30) of the filter device (1) is blocked, so that, overall, the second air flow (38) of recirculation air flowing in from the recirculation air inlet (30) is completely blocked by the recirculation air flap (17); for the first air flow (37) of fresh air flowing in from the fresh air inlet (29), the first flow path (35) is completely blocked by the fresh air flap (3); and for the first air flow (37) of fresh air flowing in from the fresh air inlet (29) through the fresh air flap (3) and the bypass air flap (10), the second flow path (36) is unobstructed, so that the first air flow (37) of fresh air flows along the second flow path (36) through the stepped filter (32), and / or B) Operating the filter device (1) with fine filtration under fresh air operation, the steps being as follows: 1) Providing a first air flow (37) of fresh air flowing in from a fresh air inlet (29) of the filter device (1), 2) Adjusting a fresh air flap (3) of the air flaps (3, 10, 17) to one of its open positions (8), whereby the first air flow (37) of fresh air flowing in from the fresh air inlet (29) is unobstructed, 3) Adjusting a bypass air flap (10) of the air flaps (3, 10, 17) to its second closed position (14), whereby, for the first air flow (37) of fresh air flowing in from the fresh air inlet (29), the second flow path (36) is blocked, 4) Adjusting a recirculation air flap (17) of the air flaps (3, 10, 17) to its closed position (20), whereby a second air flow (38) of recirculation air flowing in from a recirculation air inlet (30) of the filter device (1) is blocked, so that in total the second air flow (38) of the circulating air flowing in from the circulating air inlet (30) is completely blocked by the circulating air flap (17); for the first air flow (37) of fresh air flowing in from the fresh air inlet (29) the second flow path (36) is blocked by the bypass air flap (10); and for the first air flow (37) of fresh air flowing in from the fresh air inlet (29) through the fresh air flap (3) the first flow path (35) is open, so that the first air flow (37) of fresh air flows along the first flow path (35) through the stepped filter (32), and / or C) operating the filter device (1) in a coarse filter mode in circulating air operation, with the following steps: 1) providing a second air flow (38) of circulating air flowing in from the circulating air inlet (30) of the filter device (1), 2) adjusting the fresh air flap (3) of the air flaps (3, 10, 17) to its first closed position (6) to block the fresh air inlet (29) of the filter device (1), 3) adjusting the bypass air flap (10) of the air flaps (3, 10, 17) to its second closed position (14), whereby for the second air flow (38) of circulating air flowing in from the circulating air inlet (30) the first flow path (35) is blocked, whereas for the second air flow (38) of circulating air flowing in from the circulating air inlet (30) the second flow path (36) is open, 4) adjusting the circulating air flap (17) of the air flaps (3, 10, 17) to one of its open positions (22), whereby the second air flow (38) of circulating air flowing in from the circulating air inlet (30) is open along the second flow path (36) respectively, so that in total the first air flow (37) of fresh air flowing in from the fresh air inlet (29) of the filter device (1) is completely blocked; for the second air flow (38) of circulating air flowing in from the circulating air inlet (30) the first flow path (35) is completely blocked by the bypass air flap (10); and for the second air flow (38) of circulating air flowing in from the circulating air inlet (30) through the circulating air flap (17) and the bypass air flap (10) the second flow path (36) is open, so that the second air flow (38) of circulating air flows along the second flow path (36) through the stepped filter (32), and / or D) operating the filter device (1) in a fine filter mode in circulating air operation, with the following steps: 1) providing a second air flow (38) of circulating air flowing in from the circulating air inlet (30) of the filter device (1), 2) adjusting the fresh air flap (3) of the air flaps (3, 10, 17) to its first closed position (6) to block the fresh air inlet (29) of the filter device (1), 3) adjusting the bypass air flap (10) of the air flaps (3, 10, 17) to its second closed position (14), whereby for the second air flow (38) of circulating air flowing in from the circulating air inlet (30) the first flow path (35) is blocked, whereas for the second air flow (38) of circulating air flowing in from the circulating air inlet (30) the second flow path (36) is open, 3) adjusting the bypass air flap (10) of the air flaps (3, 10, 17) to its first closed position (13), whereby the second flow path (36) is blocked for a second air flow (38) of the cycle air flowing in from the cycle air inlet (30), whereas the first flow path (35) is open for a second air flow (38) of the cycle air flowing in from the cycle air inlet (30), 4) adjusting the cycle air flap (17) of the air flaps (3, 10, 17) to one of its open positions (22), whereby the second air flow (38) of the cycle air flowing in from the cycle air inlet (30) is open along the first flow path (35) respectively, so that overall the first air flow (37) of the fresh air flowing in from the fresh air inlet (29) of the filter device (1) is completely blocked; the second flow path (36) is completely blocked by the bypass air flap (10) for a second air flow (38) of the cycle air flowing in from the cycle air inlet (30); and the first flow path (35) is open for a second air flow (38) of the cycle air flowing in from the cycle air inlet (30) through the cycle air flap (17), the bypass air flap (10) and the fresh air flap (3), so that the second air flow (38) of the cycle air flows along the first flow path (35) through the stepped filter (32).

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