An air filter having a main air outlet and a secondary air outlet, and a filter element for the air filter

Abstract

The present invention relates to an air filter, having a filter housing with an inlet for raw air and a filter element, the filter element being arranged in the filter housing and having a filter medium, the filter medium annularly surrounding the longitudinal axis of the filter element, the filter medium separating the raw side in the filter housing from the clean side within the filter element, the filter element having a first end plate with a preferably centrally located main air port and at least one secondary air port, a main air outlet being constructed on the filter housing, the main air outlet being in communication with the clean side via the main air port, a secondary air outlet being constructed on the filter housing, the secondary air outlet being in communication with the clean side via the secondary air port. The present invention also relates to a filter element for the air filter, wherein at least one secondary air port is radially located outside the main air port and is configured as at least a radially inwardly closed break in the first end plate, and at least one secondary air port leads into a passage on the first end plate that is separate from the main air port.

Description

Field of the Invention

[0001] The present invention relates to an air filter having a raw air inlet, a main air outlet, and a secondary air outlet. The present invention also relates to a filter element for such an air filter. Background Art

[0002] Air filters having a main air outlet and a secondary air outlet for filtered air are used, for example, in internal combustion engines of motor vehicles. The main air outlet is typically used to provide (filtered) clean air for use during combustion in the internal combustion engine. The secondary air outlet can be used, for example, to provide (filtered) clean air for use in the exhaust gas line of the internal combustion engine, particularly for exhaust gas aftertreatment.

[0003] EP 1 451 464 B1 describes an intake air filter for an internal combustion engine, which has a filter housing having a raw air inlet and a clean air outlet, as well as a secondary air outlet on the clean side. The intake air filter has an annular filter element arranged in the filter housing and radially flowed through from the outside to the inside. The annular filter element has a first end plate at one axial end, the first end plate having at least one opening through which the clean air outlet communicates with the interior of the annular filter element. The annular filter element has a second end plate at the axial end facing away from the first end plate, the second end plate having at least one opening through which the secondary air outlet communicates with the interior of the annular filter element, wherein a connection pipe is constructed on the second end plate.

[0004] A similar air filter is also known from WO 2017 / 103048 A1.

[0005] WO 2012 / 172017 A1 describes a filter element having an annular filter body that surrounds an interior space in the circumferential direction. A main interface is constructed in the end plate of the filter element and is fluidly connected to the interior space. The filter body has channels that extend axially and are radially open, wherein a secondary interface fluidly connected to the interior space is arranged in the region of the channels. Summary of the Invention

[0006] The object of the present invention is to provide an air filter having a main air outlet and a secondary air outlet in which the flow through the main air outlet is not significantly affected by the flow through the secondary air outlet, and which can preferably be used to replace existing air filters that do not have a secondary air outlet. The object of the present invention is also to provide a filter element for such an air filter.

[0007] These tasks are solved by an air filter having the features given in claim 1 and a filter element according to claim 8. Preferred embodiments are given in the respective dependent claims and the description.

[0008] Air filter according to the invention

[0009] An air filter is provided according to the invention. The air filter can in particular be used for supplying filtered combustion air to an internal combustion engine. The air filter has a filter housing with an inlet for raw air. In operation of the air filter, the air to be filtered can flow through the inlet for raw air into the filter housing. The air filter also has a filter element. The filter element is arranged in the filter housing. The filter element has a filter medium body. The filter medium body circumferentially surrounds the longitudinal axis of the filter element. Directional designations such as radial or axial in the context of the description of the invention relate to the longitudinal axis of the filter element. The filter element or its filter medium body separates the raw side in the filter housing from the clean side inside the filter element. The filter element can thus be flowed through from the radially outer side to the radially inner side. In other words, the raw side is formed between the filter element and the filter housing. The raw side and the clean side can also be referred to as the raw space or the clean space.

[0010] The filter element has a first end disk. In the first end disk, a main air passage and at least one secondary air passage are configured according to the invention. The main air passage is arranged centrally on the first end disk. The main air passage can in particular be arranged coaxially with the longitudinal axis. Preferably, a plurality of secondary air passages are configured in the first end disk, and these secondary air passages can in particular be arranged in a ring around the main air passage. The filtered air can flow out or be drawn out through the main air passage and the at least one secondary air passage from the interior of the filter element, i.e., from the clean side.

[0011] The filter element generally has a second end disk. This end disk is arranged on the opposite axial end of the filter element. The second end disk of the filter element is in principle configured to be closed. The first end disk and possibly the second end disk are generally connected to the filter medium body in a material-locking manner, and the filter medium body can in particular be embedded in the material of the end disk or bonded to the end disk. The end disks can be made of synthetic material or polyurethane foam.

[0012] The filter element of the air filter according to the invention can have other features of the filter element according to the invention described below.

[0013] A main air outlet is constructed on the filter housing. The main air outlet communicates with the clean side via a main air passage. A secondary air outlet is also constructed on the filter housing. The secondary air outlet communicates with the clean side via at least one secondary air passage. In other words, the main air outlet is fluidly connected to the clean side via the main air passage and the secondary air outlet is fluidly connected to the clean side via one or more secondary air passages. During the operation of the air filter, the portion of the clean air flowing through the secondary air outlet is generally smaller than the portion of the clean air flowing through the main air outlet after filtration.

[0014] Since, according to the invention, the filtered clean air is supplied to the main air outlet and the secondary air outlet independently of each other via the main air passage or the secondary air passage in the first end plate, the flow through the main air outlet is not affected or is only insignificantly affected by the flow of clean air through the secondary air outlet. In particular, by separately introducing the clean air into the two clean air outlets in the filter housing by means of separate clean air passages in the first end plate, it is possible to achieve that the velocity profile of the air flow in the main air outlet is not affected or is at least not significantly affected qualitatively by whether air flows through the secondary air passage and the secondary air outlet, or by the magnitude of the volume flow or mass flow of the clean air flowing through the secondary air outlet.

[0015] By separating the clean air outlets on the filter housing, the main air outlet can be unproblematically adapted to the existing connection structure of the device to which the clean air is to be supplied, such as an internal combustion engine. The air filter according to the invention can thus provide an additional secondary air supply of filtered clean air without having to make changes to the connection structure (which needs to be connected to the main air outlet) for the main air supply to the device.

[0016] The secondary air outlet communicates with at least one secondary air passage via a passage of the filter element, which passage coaxially surrounds the main air passage in a ring shape. The passage can receive the flow of filtered clean air through the secondary air passage independently of the position of the secondary air passage on the periphery of the first end plate. In particular, the passage can converge and direct the partial flows of filtered clean air through a plurality, in particular all, of the secondary air passages in the first end plate to the secondary air outlet. The passage can also ensure the separation of the main air flow flowing to the main air outlet and the secondary air flow flowing to the secondary air outlet.

[0017] Preferably, the passage is radially inwardly delimited by inner wall sections on the first end plate and on the filter housing. The inner wall sections can be sealed relative to one another. In this way, it is possible to separate the passage from the main air inlet or the main air outlet in a structurally simple manner. The inner wall sections can extend in the axial direction. In special cases, it can be only the inner wall section on the first end plate or only the inner wall section on the filter housing that has an axial extension. Preferably, the inner wall sections (extending in the axial direction) overlap one another in the axial direction. This can simplify the installation of the filter element in the filter housing. A first sealing device can be arranged between the inner wall sections.

[0018] Preferably, the passage is radially outwardly delimited by outer wall sections on the first end plate and on the filter housing. The outer wall sections are sealed relative to one another. In this way, it is possible to prevent unfiltered raw air from reaching the passage on the clean side from the raw side in a structurally simple manner. The outer wall sections can extend in the axial direction. In special cases, it can be only the outer wall section on the first end plate or only the outer wall section on the filter housing that has an axial extension. Preferably, the outer wall sections (extending in the axial direction) overlap one another in the axial direction. This can simplify the installation of the filter element in the filter housing. A second sealing device can be arranged between the outer wall sections.

[0019] Preferably, the air filter has an air quality meter which is connected to the main air outlet. The air quality meter can be used to measure the mass flow or, in special cases, the volume flow of the filtered clean air flowing through the main air outlet. The air quality meter can in particular be arranged directly on the main air outlet. This allows a particularly compact structure in the axial direction. Since the supply of filtered clean air to the secondary air outlet via the secondary air inlet according to the invention does not (significantly) affect the flow through the main air outlet, the air quality meter can be arranged particularly close to the main air outlet without disturbing its measurement result. The air quality meter can be configured as a hot film air quality meter.

[0020] The housing element of the air quality meter can project through the main air outlet. The air filter can be designed shorter in the axial direction in this way.

[0021] The housing element of the air quality meter can be sealingly connected to the first end plate in the region of the main air inlet. This can simplify the connection of the air quality meter, especially considering the number of necessary sealing sites. Preferably, the sealing connection of the housing element to the first end plate is made radially inside at the secondary air inlet. The housing element can then be particularly simply connected to the filter element by being inserted in the axial direction. The housing element can be sealingly connected to the inner wall section of the passage constructed on the first end plate. A sealing element can be arranged between the housing element and the first end plate.

[0022] The secondary air outlet can be configured on the connecting pipe. This simplifies the connection of other devices, such as exhaust gas aftertreatment devices, which are to be supplied with filtered clean air through the secondary outlet, to the air filter. The connecting pipe preferably extends inclined away from the main air outlet with respect to the longitudinal axis. This is advantageous for the accessibility of the connecting pipe when connecting other devices.

[0023] Filter element according to the invention

[0024] Also falling within the framework of the present invention is a filter element. This filter element can in particular be used in the air filter according to the invention described above. The filter element according to the invention can have the other features of the filter element of the air filter according to the invention described above and vice versa.

[0025] The filter medium body of the filter element has a filter medium which annularly surrounds the longitudinal axis of the filter element. The filter medium can be flowed through from the radial outside towards the radial inside into the region of the inner hollow space of the filter medium body on the clean side. The filter medium can be made of cellulose fibers, synthetic fibers, glass fibers or a mixed medium composed of the mentioned fiber types.

[0026] The filter element has a first end disk. In the first end disk, a main air passage and at least one secondary air passage are configured according to the invention. The main air passage is arranged centrally on the first end disk. The main air passage can in particular be arranged coaxial with the longitudinal axis. The main air passage and the secondary air passage each open towards the clean side. In other words, the main air passage and the secondary air passage each open a flow path from the clean side to the surroundings of the filter element. The filtered air can flow out or be drawn off through the main air passage and the secondary air passage from the inside of the filter element, i.e. from the clean side.

[0027] According to the invention, at least one secondary air passage is radially located outside the main air passage and is configured as at least a radially inwardly closed break in the end disk. In the region of the inner peripheral edge of the end disk, in particular, a surrounding inner edge remains which defines the main air outlet.

[0028] At least one secondary air passage leads into a passage on the first end disk which is separate from the main air passage and which annularly coaxial surrounds the main air passage. This ensures that the clean air flow passes separately through the main air passage and at least one secondary air passage. In this way, it is possible to achieve that the flow through the main air passage during operation of the filter element takes place at least to a large extent independently of the flow through the secondary air passage, especially with regard to the velocity profile.

[0029] The filter element typically has a second end disk. This end disk is arranged on the opposite axial ends of the filter element. The second end disk of the filter element is in principle configured to be closed. The first end disk and possibly the second end disk are typically connected to the filter medium body in a material-locking manner, and the filter medium of the filter medium body can in particular be embedded in the material of the end disk or bonded to the end disk. The end disks can be made of synthetic material or polyurethane foam.

[0030] In a particularly preferred embodiment, the first end disk projects radially inwards beyond the inner peripheral edge of the filter medium body and forms a projecting region. At least one secondary air vent is in particular located in this projecting region. The projecting region is an overhang that projects inwards on the inner peripheral edge of the filter medium body and is in particular configured to be disk-shaped. It can also be said that the inner diameter of the end disk is smaller than the inner diameter of the filter medium body.

[0031] The first end disk preferably has a plurality of secondary air vents, which are preferably arranged annularly around the main air vent at a uniform angular pitch. Thereby, the filtered clean air can flow into the main air vent and the secondary air vents particularly uniformly. In particular, a uniform flow-through on the (inner) peripheral edge of the filter medium body can be achieved.

[0032] The filter medium can be star-pleated. Thereby, the effective filtration area of the filter medium can be increased without increasing the outer dimensions of the filter element. The pleat height measured radially in the region of the secondary air vents is smaller than the pleat height measured radially between the secondary air vents. On the one hand, the secondary air vents can thereby be arranged further outwards radially, for example to implement the main air vent larger. On the other hand, the pleats between the secondary air vents can thereby be guided further inwards radially to increase the filtration area of the filter medium body. By arranging the secondary air vents in the region of the pleats with a smaller height, it is ensured here that only the filtered clean air can reach the secondary air vents from the clean side.

[0033] Preferably, the channel is bounded radially inwards by a surrounding inner wall section that projects axially from the first end disk, wherein the inner wall section is arranged radially within at least one secondary air vent of the end disk. The inner wall section then runs between at least one secondary air vent and the main air vent. In other words, the inner wall section separates the channel from the main air vent. Generally, the inner wall section surrounds the main air vent annularly. The inner wall section is typically integrally constructed with the first end disk.

[0034] A first sealing device can be held on the inner wall section of the first end disk. The first sealing device can be configured with a sealing lip integrally formed with the inner wall section. Preferably, the first sealing device is sprayed onto the inner wall section. The end disk and the first sealing device are then configured as a two-component member. This is advantageous in view of the manufacture and operation of the filter element and reliable sealing. When the filter element is replaced, the first sealing device is replaced together. In this way, it can be ensured that when the new filter element is placed in the filter housing, the connection between the inner wall section of the first end disk and the filter housing again has the required sealing characteristics.

[0035] The first sealing device can have at least one radially outwardly directed sealing surface, preferably for sealing against the inner wall section bounding the channel of the filter housing, and / or a radially inwardly directed sealing surface, preferably for sealing against the housing element of the air quality meter. The radially inner and / or outer sealing surfaces of the first sealing device are particularly arranged on the corresponding inner and / or outer cover surfaces of the inner wall section of the end disk. The radially inwardly or outwardly directed sealing surface can be configured as an integral sealing element of the first sealing device. Alternatively, the radially inward or outward sealing surface can be configured on separate sealing elements of the first sealing device. The integral sealing element or the separate sealing elements can be sprayed onto the inner wall section. One sealing element or multiple sealing elements can be made of an elastomer. It can also be provided that at least one radially inner and / or outer sealing surface has multiple sealing lips.

[0036] Preferably, the channel is bounded radially outwardly by a surrounding outer wall section that extends radially from the first end disk. The outer wall section then runs radially outside at least one secondary air vent and is radially spaced from the inner wall section by a predetermined dimension. Preferably, the outer wall section annularly surrounds at least one secondary air vent (and the main air vent). The outer wall section is generally integrally constructed with the first end disk. By means of the outer wall section, the channels on the raw side and the clean side can be separated in the filter element installed in the filter housing.

[0037] A second sealing device can be held on the outer wall section of the first end disk. The second sealing device can be configured with a sealing lip integrally formed with the outer wall section. Preferably, the second sealing device is sprayed onto the outer wall section. The end disk and the second sealing device are then configured as a two-component member. This is advantageous in view of the manufacture and operation of the filter element and reliable sealing. When the filter element is replaced, the second sealing device is replaced together. In this way, it can be ensured that when the new filter element is placed in the filter housing, the connection between the outer wall section of the first end disk and the filter housing again has the required sealing characteristics. The second sealing device has at least one radially outward and / or radially inwardly directed sealing surface, preferably for sealing against the outer wall section of the filter housing.

[0038] Finally, it can also be provided that the inner wall section is at least partially arranged in the protruding area of the first end disk. As already described further above, the protruding area of the first end disk protrudes beyond the filter medium body with respect to its inner peripheral edge and to a certain extent forms an "overhang". If the inner wall section is now arranged in the protruding area, this means that the surrounding inner wall section runs on a diameter smaller than the inner diameter of the filter medium body. Thereby, a particularly good and low-pressure-loss fluid connection between the secondary air vent and the clean side in the region of the hollow space of the filter medium body can be achieved. Description of the Drawings

[0039] Other features and advantages of the present invention result from the following detailed description of embodiments of the present invention, from the claims, and with the aid of the drawings, which show details according to the present invention. The features mentioned above and further implemented can be realized individually or in any suitable combination in groups in a variant of the present invention. The features shown in the drawings are presented so that the characteristics according to the present invention can become clearly visible.

[0040] Wherein:

[0041] Figure 1 An air filter according to the present invention is shown in a schematic cross-sectional view, having: an annular filter element according to the present invention, which has a first end disk having a central main air vent and a plurality of secondary air vents arranged annularly around the main air vent; and a filter housing on which a central main air outlet and an eccentrically arranged secondary air outlet are formed, wherein the main air outlet communicates with the main air vent and the secondary air outlet communicates with the secondary air vent via an annular channel;

[0042] Figure 2 Shown in a schematic exploded view Figure 1 of the air filter;

[0043] Figure 3 Showing details in the area where the filter element is connected to the filter housing and to the air quality meter from Figure 1 ;

[0044] Figure 4 Shown in a schematic view of the air filter Figure 1 along the longitudinal axis of the filter element. Detailed Description of the Embodiment

[0045] Figure 1 An air filter 10 is shown in a cross-sectional view. In Figure 2 the air filter 10 is shown in an exploded view.

[0046] The air filter 10 has a filter housing 12. A filter element 14 is arranged in the filter housing 12. The filter element 14 has a filter medium body 16. The filter medium body 16 annularly surrounds the longitudinal axis 18 of the filter element 14. The filter element 14 can be flowed through from the radial outside to the radial inside. The filter medium is here configured as a star pleat. At the axial ends of the filter element 14, a first end disk 20 and a second end disk 22 are connected to the filter medium body 16.

[0047] The filter housing 12 here has a first housing part 24 and a second housing part 26. For operating the air filter 10, the first housing part 24 and the second housing part 26 are fastened to each other, cf. Figure 1 , for example, by snapping into each other. For replacing the filter element 14, the two housing parts 24, 26 can be loosened from each other.

[0048] The filter housing 12 has a raw air inlet 28. The raw air inlet 28 is here configured as a nozzle 30 on the second housing part 26, see Figure 2 . Inside the filter housing 12, the filter element 14 separates the raw side 32 from the clean side 34. The raw side 32 is the space outside the filter element 14. The clean side 34 is the space inside the filter medium body 16 and between the end disks 20, 22. To separate the raw side 32 from the clean side 34, the second end disk 22 is configured to be closed. The raw side 32 can also be referred to as the raw space and the clean side 34 as the clean space. When the air filter 10 is operating, the raw air to be filtered flows through the raw air inlet 28 onto the raw side 32. The air flows from the raw side 32 through the filter medium and arrives at the clean side 34 as filtered clean air.

[0049] The first end disk 20 has a main air port 36. The main air port 36 can be centered on the first end disk 20. Here, the main air port 36 is coaxially arranged with the longitudinal axis 18 of the filter element 14.

[0050] The first end disk 20 also has a plurality of secondary air ports 38. The secondary air ports 38 are here arranged annularly around the main air port 36. In other words, the secondary air ports 38 surround the main air port 36 radially on the outside.

[0051] The main air port 36 and the secondary air port 38 are each configured as breaks in the first end disk 20. The main air port 36 and the secondary air port 38 each open a flow path from the clean side 34 to the surroundings of the filter element 14. Here, the secondary air port 38 (and thus also the main air port 36) is arranged radially within the filter medium body 16. In an embodiment of the air filter 10 not shown in detail, each fold of the star-shaped pleated filter medium between adjacent secondary air ports 38 may project radially beyond the secondary air port 38 towards the longitudinal axis 18. The folds between the secondary air ports 38 in this case have a greater fold height measured in the radial direction than those folds whose peripheral position coincides with one of the secondary air ports 38.

[0052] The main air outlet 40 is configured on the filter housing 12. The main air outlet 40 communicates with the clean side 34 via the main air port 36. In other words, the main air outlet 40 is fluidly connected to the clean side 34 via the main air port 36. During operation of the air filter 10, the main part of the filtered clean air generally flows out of the air filter 10 from the clean side 34 through the main air port 36 and the main air outlet 40.

[0053] In addition, the secondary air outlet 42 is configured on the filter housing 12. The secondary air outlet 42 may be provided on the connecting pipe 44. The connecting pipe 44 of the secondary air outlet 42 extends obliquely away from the longitudinal axis 18 here. The secondary air outlet 42 communicates with the clean side 34 via the secondary air port 38. In other words, the secondary air outlet 42 is fluidly connected to the clean side 34 via the secondary air port 38. During operation of the air filter 10, a generally smaller part of the filtered clean air may flow out of the air filter 10 from the clean side 34 through the secondary air port 38 and the secondary air outlet 42.

[0054] To fluidly connect the secondary air outlet 42 to the secondary air port 38, the channel 46 is provided. Here, all the secondary air ports 38 merge into the channel 46. The channel 46 annularly surrounds the main air port 36 or the main air outlet 40. The channel 46 causes the main air flow of the filtered clean air through the main air port 36 and the main air outlet 40 to be separated from the secondary air flow of the filtered clean air through the secondary air port 38 and the secondary air outlet 42.

[0055] Axially away from the filter element 14, the channel 46 may be bounded by the housing wall of the filter housing 12, here referring to the housing wall of the first housing part 24. A break 47 may be configured in the housing wall, which fluidly connects the channel 46 to the secondary air outlet 42, also for reference Figure 3 . Axially towards the filter medium, the channel 46 may be bounded by the first end disk 20.

[0056] Radially outwardly, the channel 46 can be delimited by the outer wall sections 48, 50 on the first end disk 20 or the filter housing 12. The outer wall section 48 is integrally formed with the first end disk 20 here. The outer wall section 48 projects axially beyond the part of the first end disk 20 that extends perpendicular to the longitudinal axis 18. In other words, the outer wall section 48 projects axially from the first end disk 20. The outer wall section 50 projects axially from the first housing part 24 into the interior of the filter housing 12 here. In other words, the outer wall section 50 projects axially from the filter housing 12, here from its first housing part 24.

[0057] The outer wall sections 48, 50 can overlap each other axially. Here, the outer wall section 48 of the first end disk 20 is radially arranged outside the outer wall section 50 of the filter housing 12.

[0058] A sealing device 52 can be arranged between the outer wall sections 48, 50. The sealing device 52 can be held on the outer wall section 48 of the first end disk 20. Here, the sealing device 52 is sprayed onto the outer wall section 48. The first end disk 20 and the sealing device 52 thus form a two-component member. Alternatively, the sealing device 52 can be implemented as a separate sealing device, such as an O-ring, held on the outer section 48. Alternatively (not shown in the figures), the sealing device 52 can also be held on the housing-side outer wall section 50.

[0059] Radially inwardly, the channel 46 can be delimited by the inner wall sections 54, 56 on the first end disk 20 or the filter housing 12. The inner wall section 54 is integrally formed with the first end disk 20 here. The inner wall section 54 projects axially beyond the part of the first end disk 20 that extends perpendicular to the longitudinal axis 18. In other words, the inner wall section 54 projects axially from the first end disk 20. The inner wall section 56 projects axially from the first housing part 24 into the interior of the filter housing 12 here. In other words, the inner wall section 56 projects axially from the filter housing 12, here from its first housing part 24. The inner wall section 54 of the first end disk 20 can separate the main air vent 36 from the channel 46.

[0060] The inner wall sections 54, 56 can overlap each other axially. Here, the inner wall section 54 of the first end disk 20 is radially arranged inside the inner wall section 56 of the filter housing 12. Thus, in the illustrated air filter 10, the outer wall section 50 and the inner wall section 56 of the filter housing 12 run between the outer wall section 48 and the inner wall section 54 of the filter element 14.

[0061] Between the inner wall sections 54, 56, a first sealing section 58 of the sealing device 60 can be arranged. The sealing device 60 can be held on the inner wall section 54 of the first end plate 20. Here, the sealing device 60 or the sealing section 58 is sprayed onto the inner wall section 54. In this regard, the first end plate 20 and the sealing device 60 (and the sealing device 52, see above) also form a two-component member. Alternatively, the sealing device 60 can be implemented as a separate sealing device such as an O-ring held on the inner wall section 54.

[0062] The air filter 10 can have an air quality meter 62. The air quality meter 62 is fluidly connected to the main air outlet 40. The air quality meter 62 is used to measure the mass flow of the filtered clean air through the main air outlet 40. The housing element 64 of the air quality meter 62 can project through the main air outlet 40. The housing element 64 is here sealingly connected to the first end plate 20. In the illustrated embodiment of the air filter 10, the housing element 64 extends into the main air opening 36. In the axial direction, the inner wall section 54 of the first end plate 20 and the housing element 64 of the air quality meter 62 overlap each other. Between the first end plate 20, here its inner wall section 54 and the housing element 64, a second sealing section 66 of the sealing device 60 can be arranged. The second sealing section 66 is also sprayed onto the inner wall section 54 here. Currently, the two sealing sections 58, 66 of the sealing device 60 are constructed separately. In an alternative embodiment not shown in detail, the sealing device 60 can have an integral sealing element on which the two sealing sections 58, 66 are constructed.

[0063] In order to set the insertion depth of the housing element 64 defined in the filter housing 12, a stop 68 can be constructed on the housing element 64. By means of two screws 70 passing through the stop 68, the air quality meter 62 can be fixed to the filter housing 12, here its first housing part 24, see Figure 2 and in particular Figure 4 . The screws 70 are here inserted into a connection piece 72 surrounding the main air outlet 40.

[0064] The air quality meter 62 can be constructed as a hot-film air quality meter with a (very abstractly shown) hot-wire anemometer 74. In particular in Figure 1 and 4It can be seen from [description] that the hot-wire anemometer 74 extends into the housing element 64 of the air quality meter 62. The measurement accuracy of the hot-wire anemometer depends on the inflow pattern or the air mass flow velocity profile flowing through. Changes in the inflow or velocity profile result in biased measurement results. By connecting the secondary air outlet 42 to the cleaning side 34 via secondary air vents 38 that are arranged annularly around the main air vent 36 and lead to a common channel 46 according to the present invention, the flow-through of the air quality meter 62 can be ensured to be not significantly affected by the amount of cleaning air extracted through the secondary air outlet 42. The air filter 10 according to the present invention thus ensures a particularly accurate measurement of the air mass flow through the main air outlet 40.

Claims

1. An air filter (10), comprising: a filter housing (12), the filter housing having a raw air inlet (28), and Filter element (14), which is arranged in the filter housing (12) and has a filter medium body (16) that annularly surrounds the longitudinal axis (18) of the filter element (14), wherein, the filter medium body (16) separates the raw side (32) in the filter housing (12) from the clean side (34) within the filter element (14), wherein the filter element (14) has a first end plate (20), the first end plate having a central main air port (36) and at least one secondary air port (38), wherein a main air outlet (40) is formed on the filter housing (12), and the main air outlet communicates with the clean side (34) of the filter element (14) via the main air port (36), wherein the at least one secondary air port (38) is radially located outside the main air port (36) and is configured as at least a radially inwardly closed break in the first end plate (20), and wherein a secondary air outlet (42) is formed on the filter housing (12), and the secondary air outlet communicates with the clean side (34) of the filter element (14) via the secondary air port (38), wherein the secondary air outlet (42) communicates with the at least one secondary air port (38) via a channel (46) of the filter element (14), and the channel coaxially surrounds the main air port (36) in a ring shape.

2. The air filter (10) according to claim 1, characterized in that, The channel (46) is radially bounded inwardly by inner wall sections (54, 56) on the first end plate (20) on one hand and on the filter housing (12) on the other hand, wherein the inner wall sections (54, 56) are sealed against each other.

3. The air filter (10) according to claim 2, wherein, The inner wall sections (54, 56) overlap each other in the axial direction.

4. The air filter (10) according to any one of claims 1 to 3, characterized in that, The channel (46) is radially bounded outwardly by outer wall sections (48, 50) on the first end plate (20) on one hand and on the filter housing (12) on the other hand, and the outer wall sections are sealed against each other.

5. The air filter (10) according to claim 4, characterized in that, The outer wall sections (48, 50) overlap each other in the axial direction.

6. The air filter (10) according to any one of claims 1 to 3, further comprising an air quality meter (62), the air quality meter being connected to the main air outlet (40).

7. The air filter (10) according to claim 6, characterized in that, A housing element (64) of the air quality meter (62) projects through the main air outlet (40).

8. The air filter (10) according to claim 6, characterized in that, The housing element (64) of the air quality meter (62) is sealingly connected to the first end plate (20) in the region of the main air port (36).

9. The air filter (10) according to claim 8, characterized in that, The housing element (64) of the air quality meter (62) is sealingly connected to the first end plate (20) radially within the secondary air port (38).

10. The air filter (10) according to any one of claims 1 to 3, characterized in that, The secondary air outlet (42) is formed on a connection pipe (44).

11. The air filter (10) according to claim 10, characterized in that, The connection pipe (44) extends away from the main air outlet (40) inclined to the longitudinal axis (18).

12. Filter element (14) having a filter medium body (16) which annularly surrounds the longitudinal axis (18) of the filter element (14), wherein, The filter medium body (16) can be flowed through from the radial outside to the radial inside in the region of the internal hollow space of the filter medium body (16) on the clean side (34) within the filter element (14). The filter element (14) has a first end disk (20), which has a central main air vent (36) and at least one secondary air vent (38). The at least one secondary air vent (38) is radially located outside the main air vent (36) and is configured as at least a radially inwardly closed break of the first end disk (20), and the at least one secondary air vent (38) leads into a passage (46) on the first end disk (20) that is separate from the main air vent (36), and the passage coaxially surrounds the main air vent (36) annularly.

13. The filter element (14) according to claim 12, characterized in that, The first end disk (20) projects radially inward beyond the inner peripheral edge of the filter medium body (16) and forms a projecting region.

14. The filter element (14) according to claim 13, characterized in that, The at least one secondary air vent (38) is located in the projecting region.

15. The filter element (14) according to any one of claims 12 to 14, characterized in that, The first end disk (20) has a plurality of secondary air vents (38).

16. The filter element (14) according to claim 15, characterized in that, The secondary air vents are arranged annularly around the main air vent (36) at a uniform angular pitch.

17. The filter element (14) according to any one of claims 12 to 14, characterized in that, The filter medium body (16) has a star-folded filter medium.

18. The filter element (14) according to claim 17, characterized in that, The pleat height measured in the radial direction in the region of the secondary air vents (38) is less than the pleat height measured in the radial direction between the secondary air vents.

19. The filter element (14) according to claim 13, characterized in that, The passage (46) is radially bounded inwardly by a surrounding inner wall section (54) that projects axially from the first end disk (20), and the inner wall section (54) is radially arranged within the at least one secondary air vent (38) of the first end disk (20).

20. The filter element (14) according to claim 19, characterized in that, A first sealing device (60) is held on the inner wall section (54) of the first end disk (20).

21. The filter element (14) according to claim 20, characterized in that, The first sealing device (60) is sprayed onto the inner wall section (54).

22. The filter element (14) according to claim 20, characterized in that, The first sealing device (60) provides at least one radially inner sealing surface on the radially inner cover surface of the inner wall section (54) and at least one radially outer sealing surface on the outer cover surface of the inner wall section (54).

23. The filter element (14) according to claim 19, characterized in that, The passage (46) is radially bounded outwardly by a surrounding outer wall section (48) that projects axially from the first end disk (20) and the outer wall section is spaced from the inner wall section (54) by a predetermined dimension in the radial direction.

24. The filter element (14) according to claim 23, characterized in that, A second sealing device (52) is held on the outer wall section (48) of the first end disk (20).

25. The filter element (14) according to claim 24, characterized in that, The second sealing device (52) is sprayed onto the outer wall section (48).

26. The filter element (14) according to claim 24, characterized in that, The second sealing device (52) provides at least one radially inner and / or at least one radially outer sealing surface on the radially inner and / or radially outer cover surface of the outer wall section (48).

27. The filter element (14) according to claim 23, characterized in that, The inner wall section (54) is at least partially arranged in the projecting region of the first end disk (20).

28. The filter element (14) according to any one of claims 12 to 14, characterized in that, The filter element (14) is for use in an air filter (10) according to any one of the preceding claims 1 to 11.

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