Filters and the use of a main filter element as well as the use of a secondary filter element

Abstract

Filter (10) for filtering air for an internal combustion engine, comprising a filter housing (12) into which a main filter element (100) and a secondary filter element (200) are inserted, wherein the main filter element (100) has an inlet area (110), an outlet area (112) and a main flow direction (X1) perpendicular to the inlet area (110), a filter body (120) and a filter element frame (118) supporting the filter body (120), and the secondary filter element (200) is arranged downstream of the main filter element (100), wherein the filter element frame (118) has a seal (116) in the region of the outlet area (112) for separating the filter housing (12) into a clean side and a dirty side and a spacer structure (128) that determines the distance between the filter element frame (118) and the secondary filter element (200), wherein the outlet area (112) and a The sealing surface (114) of the seal (116) forms an angle (α) of 24°±10° with the inflow surface (110).

Description

Technical FieldThe present invention relates to a filter, in particular for internal combustion engines, for filtering a fluid, in particular air, and to a filter insert, in particular for such a filter.Prior ArtEngine air filtration is becoming increasingly important, particularly in construction and agricultural machines. Firstly, more and more powerful air filters are being used, since higher engine powers and more stringent emission regulations require an increased air throughput through the engine. On the other hand, the number of assemblies which are installed as standard, such as air conditioners, increases. This reduces the space available in the vehicle. Finally, there is a tendency to make vehicles smaller and lighter, which likewise takes up the savings of the available installation space.For use in vehicles which offer little installation space for filtration purposes, what are known as compressed air or Z filters with channels which are alternately closed and are formed by corrugated and smooth layers of a filter medium lying one on top of the other and through which flow can take place in-line are generally used. This means that the inflow direction and the outflow direction run parallel and are substantially aligned with one another. Often, the air flowing out of the air filter must be deflected after flowing through the filter, depending on the application. For this purpose, a pipe elbow can be connected downstream of the filter housing, for example. However, downstream components of this type again increase the installation space requirement of the entire arrangement.From EP 2 106 836 A1 a filter cartridge is known which consists of a filter element which is made for example from concertina-folded paper and which delimits in the filter housing into which it is inserted an upstream chamber in which the air still to be filtered is located and a downstream chamber in which the already filtered air is located. The filter element has an upstream side facing the upstream chamber and a downstream side facing the downstream chamber. The upstream and downstream sides are substantially non-parallel and inclined to each other. This allows the manufacture of filter housings and filter assemblies with reduced size without compromising their efficiency. Further, a filter housing for this cartridge and the filter unit equipped with this cartridge are disclosed.WO 2009 / 106 593 A1 discloses an air filter arrangement having a filter element with a first filter bellows and a downstream safety filter element, wherein the filter element has an outflow geometry corresponding to the inflow geometry of the safety filter element.WO 2009 / 106 590 A1 discloses a filter element and an air filter for an internal combustion engine, having a sealing arrangement which is optimized by a safety system for protection against incorrect installation of a filter element in an air filter housing.WO 2010 / 019 797 A1 discloses filters. The filter comprises a sheet of filter media comprising a body having an upper portion, a lower portion, a first end surface proximate the upper portion, a second end surface proximate the lower portion, a first side surface extending between the first and second end surfaces, one or more of the upper and lower portions defining a ledge, the ledge defining a third end surface disposed between the first and second end surfaces and a second side surface extending between the first and third end surfaces; and a seal disposed on the ledge.A filter element is known from DE 10 2009 060 214 A1, in particular for filtering gases, having a filter medium, having a supporting frame which encloses the filter medium in a closed manner laterally in a sealed manner, and having a seal which is arranged on the supporting frame and encloses the filter medium in a closed manner laterally in a closed manner. A simplified adaptability to different installation situations results if the supporting frame is a separately produced component with respect to the filter medium and is fitted to the filter medium.EP 1 494 785 B1 discloses a filter element, a safety element and a liquid cleaning device. The liquid cleaner assembly generally includes a housing having a lid and a primary liquid cleaner portion. The element generally comprises Z filter media arranged in a straight flow configuration and an axial seal positioned to extend continuously about the outer periphery of the straight flow structure. A precleaner may be disposed in the liquid cleaner assembly. Methods of assembly and use are provided.An internal combustion engine is known from DE 10 2005 026 811 A1, preferably an air-cooled internal combustion engine, having an air filter system with at least one filter element, in particular further having a pre-separator, wherein the air filter system has a solid particle discharge opening upstream of the last filter element in the direction of flow, and a fan arrangement, having a holding frame and a fan impeller arranged therein for producing a cooling air flow, wherein the solid particle discharge opening is correspondingly connected to the suction side of the fan impeller in such a way that the solid particles collected in the air filter system are suctioned off by the negative pressure of the fan impeller.It is a first object of the invention to specify a filter, in particular for internal combustion engines, for filtering a fluid, in particular air, which requires less installation space with comparable filter performance.When used in construction or agricultural machines, vibrations are transmitted to the filter in different operating states. It is therefore a primary object to arrange the main filter insert in the filter in a vibration-proof manner. However, a secure fit is also important during operation in the case of a secondary filter insert arranged downstream.It is a second object of the invention to specify a filter, in particular for internal combustion engines, for filtering a fluid, in particular air, which has a high reliability even under extreme operating conditions.In the aforementioned fields of application, it is necessary to design the overall construction of a filter insert as robust as possible. Protection of the filter medium during operation is crucial. In the design of such filter inserts, consideration must also be given to any handling habits in the event of a change of the filter insert or in the event of maintenance.It is thus a third object of the invention to specify a filter insert which ensures reliable filter function even in extreme use conditions and handling habits.With the integration becoming higher and higher, a particularly high reliability of each component of such a filter is important for long maintenance intervals. In the aforementioned fields of application, in addition to the high fluid flow rates, high mechanical loads such as, for example, vibrations also require a particularly stable construction of the overall system.It is a fourth object of the invention to specify a filter insert which has a particularly high reliability due to a robust construction.In addition to the external dimensions of an air filter, the maximum possible air throughput and the service life of a filter, the pressure drop caused by the air filter is a decisive core variable in the evaluation of the performance of an air filter.It is a fifth object of the invention to make the pressure drop of a filter insert for a filter as low as possible for a given external geometry.For use in vehicles which offer little installation space for filtration purposes, what are known as compressed air filters are generally used, through which flow can take place in-line. This means that the inflow direction and the outflow direction run parallel and are substantially aligned with one another. Often, the air flowing out of the air filter must be deflected after flowing through the filter, depending on the application. For this purpose, a pipe elbow can be connected downstream of the filter housing, for example. However, downstream components of this type again increase the installation space requirement of the entire arrangement.It is a sixth object of the invention to specify a filter, in particular for internal combustion engines, for filtering a fluid, in particular air, which requires less installation space with comparable filter performance.The above-mentioned objects are achieved in each case by various aspects of the embodiments of a filter described below, in particular for internal combustion engines, for filtering a fluid, in particular air, and a filter insert, in particular for such a filter. As can be seen from the exemplary embodiments, the various aspects can advantageously be contained individually or in combination in embodiments, wherein, when individual aspects are combined, the advantages of other aspects support and a synergistic interaction results in an advantageous product.Disclosure of the InventionThe first object is achieved by a filter insert for a filter, in particular for internal combustion engines, for the filtration of a fluid, in particular air, according to claim 1. Further embodiments of the invention are specified in the dependent claims.The filter insert according to the invention has a prismatic basic shape, wherein the base surface and cover surface arranged parallel to one another have a polygonal basic shape. The filter insert has, corresponding to the polygonal basic shape of the base and cover surfaces, at least three, preferably four, shell surfaces. A first lateral surface is adjacent to a second lateral surface. Both the first lateral surface and preferably the second lateral surface are inflow surfaces. Alternatively, the first lateral surface and preferably additionally the second lateral surface are outflow surfaces. The first lateral surface and the second lateral surface are substantially perpendicular to each other. An angle range of 80° to 100° is substantially included. A third lateral surface is preferably situated substantially opposite the first lateral surface or is spaced apart therefrom in the flow direction and, in contrast to the first and second lateral surfaces, is an outflow surface if the first and the second lateral surface are inflow surfaces, or the third lateral surface is an inflow surface if the first and preferably the second lateral surface are outflow surfaces. The third lateral surface encloses an angle with the first lateral surface which is less than 80° and greater than 10° and is in particular between 70° and 20°. Particular preference is given to angles such as 45° or 60°.The first alternative mentioned above is described below, in which the first and preferably also the second lateral surface are inflow surfaces and the third lateral surface is outflow surface. The explanations apply correspondingly to the reverse case of the second alternative, in which the first and the second lateral surface are outflow surface and the third lateral surface are inflow surface. In the filter insert geometry described, a lateral surface is generally produced as the inflow surface, which is first struck by the main fluid flow. The second jacket surface assists the entry of the fluid into the filter insert and increases the inflow surface. The fluid flows off via the third lateral surface. Because the third jacket surface is inclined to the first jacket surface, it is possible for a filter with such a filter insert to fix the outflow direction already within the filter housing in the desired manner. An external deflection outside the filter housing, for example by means of a curved outflow connector, is no longer necessary. Thus, two advantages are obtained. On the one hand, a clearly enlarged inflow surface results, which enables a possibly better utilization of the filter capacity. At the same time, the filter geometry according to the invention allows a deflection of the main flow direction within the filter insert, as a result of which the installation space occupied by the filter can be optimized, that is to say reduced.The main flow direction is understood to mean the averaged direction of the flow at a position of the path through the filter system and / or filter element. For example, the main flow direction within a cyclone block of a plurality of inline cyclone cells is defined by the axial extent of the cyclone cells. When hitting the inflow surface of a filter element, the main flow direction will be substantially perpendicular to this inflow surface and otherwise defined by the path of least resistance.According to one embodiment, the polygonal basic shape is a triangle, quadrilateral or pentagonal. The resulting prismatic basic shape can also have slightly curved lateral surfaces depending on the application. In addition, an inflow or outflow can take place via the base and / or top surface of the prism.A preferred further development of the invention provides that the filter insert has a filter body with a filter medium folded in zigzag form. A filter medium folded in this way has a high surface and can be brought into the desired basic shape in a relatively cost-effective manner.One embodiment provides that the folds have outer folded edges which lie on the first lateral surface and have inner folded edges which are opposite the outer folded edges and lie on the third lateral surface. Thus, an inflow to the filter insert takes place substantially perpendicularly to the folded edges. The same applies to the outflow, wherein the third lateral surface is inclined with respect to the first lateral surface.In the case of the described zigzag-shaped folding of the filter medium, the folds have at least one end side which comes to lie on the second lateral surface. The flow against the filter medium thus takes place both via the fold edge and via the end face of the fold. In this case, the end faces must be designed such that no direct inflow to the clean side of the filter insert can take place.A particularly preferred embodiment of the invention provides that the depth of adjacent folded edges differs and in particular every second fold has the same depth. The different depth of adjacent folded edges enables a bevelling of the filter insert and thus the formation of the desired geometry.A particularly preferred embodiment of the invention provides that the folds each have two end faces. One end face of the folds lies on the second lateral surface. The other end face of the folds lies on a fourth lateral surface. The second lateral surface is larger than the fourth lateral surface. The fourth lateral surface has more folded edges than the second lateral surface, in particular twice as many. By doubling the folded edges on the fourth lateral surface, it is possible to establish and adjust the angle between the third lateral surface and the first lateral surface.The inventive concept also finds precipitation in a filter having a filter insert according to the invention. In such a filter, it can be provided that the main inflow direction of the filter and the main outflow direction of the filter enclose an angle of more than 30°, in particular more than 45°, preferably more than 60° and in particular 90°.Alternatively, it can be provided that the main inflow direction of the filter is parallel and offset to the main outflow direction of the filter. Due to the inclination of the outflow surface of the filter insert to the inflow surface of the filter insert realized by the filter insert, a deflection of the main inflow direction to the main outflow direction can take place within the filter in such a way that the main outflow direction encloses an angle with the main inflow direction or is offset by a specific length. This can be realized simply and cost-effectively by corresponding outflow openings on the filter.A likewise advantageous further development of the invention provides a filter having a primary filter element according to the invention and a secondary filter element according to the invention. The configuration of the primary and secondary filter inserts with a prismatic basic shape results in a particularly great freedom of deflection of the fluid flows in such a filter.The second object is achieved by a filter insert for a filter for filtering a fluid, in particular air, in particular for an internal combustion engine according to claim 11. Further embodiments of the invention are specified in the dependent claims.The filter insert according to the invention has an inflow surface, an outflow surface and a main flow direction, a filter body and a filter insert frame carrying the filter body. The filter insert frame has, in the region of the outflow surface, a seal for separating a filter interior in the clean side and the raw side and a spacer structure for defining a distance between the filter insert frame and a further filter insert which can be arranged downstream in the main flow direction. By means of the spacer structure, a predefined distance between filter insert, which can be a main filter insert, for example, and a further filter insert arranged downstream, which can be a secondary filter insert, for example, is maintained even under extreme operating conditions such as vibrations, for example. This ensures that the further filter insert cannot move out of its intended position and thus can lose its sealing function and securing function.In one embodiment of the invention, it is provided that the spacer structure is arranged within the seal, in particular multiple times along the seal and in particular on the periphery of the outflow surface. In such a configuration, it can be provided that the outer periphery follows perpendicularly to the main flow direction of the further filter insert in terms of the shape and size of the seal and thus offers a supporting surface for the spacer structure.An advantageous embodiment of the invention provides that the outflow surface and / or a sealing surface of the seal encloses an angle of between 5° and 45°, in particular an angle of 24°±10° and in particular an angle of 24°±5°, with the main flow direction. An outflow surface angled in this way to the main flow direction has a larger surface than the inflow surface. In general, the development of the outflow surface and / or of the sealing surface offers the possibility of already carrying out a deflection of the main flow direction within the filter insert or directly following the filter insert. This saves installation space and improves the pressure loss within the filter due to shorter flow paths.Advantageously, the spacer structure is formed integrally with the seal, in particular formed into the seal. This allows, for example, the use of the same material and the production of the spacer structure in the same working step as the seal.A particularly preferred embodiment provides that the spacer structure is designed to exert a clamping or holding force on a further filter insert, in particular a secondary filter insert, which can be arranged downstream in the main flow direction in the installed state of the filter insert, wherein the force presses the further filter insert into its installed position. This can be achieved, for example, by the spacer structure being produced from an elastic material. If the filter insert is then inserted after the further filter insert, the insertion can already exert a force on the further filter insert by the suitable selection of a corresponding geometry. This in turn improves the reliability of the filter, since the further filter insert is permanently exposed to a force which holds it in its intended place.In a preferred embodiment of the invention, the seal acts axially in the direction of the main flow direction. This means that the force to be applied for sealing runs parallel to the outflow direction.In one embodiment of the invention, the filter body is designed as a filter bellows, in particular with a variable fold height. By means of the variable fold height, for example, an outflow surface running obliquely to the main flow direction can be realized. A variable fold height is understood to mean a structure of a filter body folded in a zigzag shape, in which the fold heights are not constant over a length of the bellows defined by the stringing of folded edges, but instead change continuously or discontinuously or differ in adjacent sections. Preferably, the height of the pleats continuously and more preferably linearly changes along the length of the bellows.The object is also achieved by a filter for filtering a fluid, in particular air, in particular for an internal combustion engine. The filter according to the invention has a filter housing into which a main filter insert and a secondary filter insert can be inserted. The main filter insert has an inflow surface, an outflow surface and a main flow direction, a filter body and a filter insert frame carrying the filter body. The secondary filter insert can be arranged downstream of the main filter insert. The filter insert frame has, in the region of the outflow surface, a seal for separating the filter housing in the clean side and the raw side and a spacer structure for defining a distance between the filter insert frame and the secondary filter insert.In an embodiment of the filter according to the invention, it is provided that the filter housing has an introduction direction which lies substantially perpendicular to the main flow direction. This allows the main filter insert to be inserted after the secondary filter insert has been inserted in such a way that the secondary filter insert is blocked from moving out of its intended seat.In a preferred embodiment, it is provided that the secondary filter insert has a seal for bearing against the filter housing, wherein the seal is designed to act in particular radially with respect to the flow direction of the secondary filter insert. It is therefore not necessary to provide a sealing surface on the filter housing in axial extension to the main flow direction of the secondary filter insert. Rather, the seal acts perpendicularly to the main flow direction against the filter housing already during the insertion into the provided seat.According to one embodiment of the invention, the secondary filter insert has a secondary filter body and a secondary filter insert frame carrying the secondary filter body. In this case, it can be provided that, in the inserted state of the main filter insert and of the secondary filter insert, the spacer structure of the main filter insert contacts the seal or the secondary filter insert frame of the secondary filter insert. Thus, in the event of vibrations occurring in the case of use, it is not possible to move the secondary filter insert out, since the spacer structure of the main filter insert blocks the space over which the secondary filter insert was inserted.The third object is achieved by a filter insert for a filter for filtering a fluid, in particular air, in particular for an internal combustion engine according to claim 24. Further embodiments of the invention are specified in the dependent claims.The filter insert according to the invention for a filter for filtering a fluid, in particular air, in particular for an internal combustion engine, has an inflow surface, an outflow surface, a main flow direction, a filter body and a filter insert frame carrying the filter body. The filter insert frame has, in the region of the outflow surface, a seal for separating a filter interior of a filter in the clean side and the raw side and, in the region of the inflow surface, an edge guard surrounding the filter frame on the outside. The edge guard connects the filter body and the filter insert frame to one another. According to the invention, a synergistic interaction thus results between edge protection and the connection of the filter body to the filter insert frame. This is particularly advantageous in the conventional practice in the construction machine sector for cleaning filter inserts by blowing out or knocking out.In particular, in particularly preferred embodiments, it is provided that the edge guard forms a connection between the filter body and the filter insert frame that is tight for the fluid to be filtered. Thus, the connection of filter body and filter insert frame simultaneously forms the seal of the filter body with respect to the filter insert frame.In a further development of the invention according to the invention, it is provided that the filter insert frame has recesses in the region of the edge guard, which recesses are filled by the edge guard. This enables a particularly good mechanical connection between the edge guard and the filter insert frame.Particularly preferably, the recesses extend perpendicular to the main flow direction. It is therefore not necessary to provide a development for the edge protection in the filter insert frame. Rather, the edge guard can lie completely around the inflow-side edges of the filter insert frame and at the same time penetrate the filter insert frame through the recesses and thus enter into a particularly mechanically stable connection.In one embodiment of the invention, the filter insert frame surrounds the filter body. In addition, the filter insert frame determines the main flow direction of the filter insert.A particularly preferred embodiment of the invention provides that the edge guard partially penetrates the filter body. Thus, after the edge protector has cured, a particularly stable connection is obtained between the edge protector and filter insert frame on the one hand and the filter insert frame and filter body on the other hand.A further development of the invention provides that the filter body is designed as a filter bellows, in particular with a variable fold height. The variable fold height allows an angular deflection between the outflow surface and the main flow direction.According to the invention, it can be provided that the outflow surface and / or a sealing surface of the seal encloses an angle of between 5° and 45°, in particular an angle of 24°±10° and in particular an angle of 24°±5°, with the main flow direction. The angle between the main flow direction and the outflow surface or / and the sealing surface permits a particularly compact construction, since a deflection of the main alignment can already take place within a filter housing accommodating the filter insert.A particularly preferred further development of the invention provides that the connection between the filter body and the filter insert frame is an adhesive bond which is formed integrally with the edge guard. In particular, the adhesive bond and the edge protection can be formed from the same material, in particular from a polyurethane. This enables technical advantages in particular during production, since the adhesion between the filter insert frame and filter body, the sealing between filter body and filter insert frame and the edge protection can be produced in one working step and at the same time a particularly robust embodiment is produced.According to the invention, the edge guard is designed such that the forces occurring during knocking out of the filter insert can be at least partially absorbed by the edge guard and, in particular, damage to the filter insert can be prevented.The fourth object is achieved by a secondary filter insert for a filter for filtering a fluid, in particular air, in particular for an internal combustion engine according to claim 35. Further embodiments of the invention are specified in the dependent claims.The secondary filter insert according to the invention is designed to be inserted into a filter downstream of a main filter insert. It has an inflow surface, an outflow surface and an outflow direction. Furthermore, the secondary filter insert has a filter body, through which flow can take place along the outflow direction, and a filter insert frame carrying the filter body. The filter insert frame has a seal for separating a filter interior of a filter in the clean side and the raw side as well as an adhesion between the filter body and the filter insert frame. The separate execution of the seal and the adhesive bonding allows a substantially more stable configuration of the adhesive bonding.In a preferred embodiment of the invention, the seal is designed to act radially with respect to the main flow direction and in particular runs around the secondary filter insert substantially perpendicularly with respect to the main flow direction. The seal may comprise a sponge rubber.It is particularly preferably provided that a carrier section of the filter insert frame runs around the filter body and the carrier section has an inner edge, in particular a groove, on the inner side for receiving an adhesive material of the adhesive bond. This enables a mechanically particularly stable connection between the filter body and filter insert frame. In particular, it can be provided that the depth of the groove extends in the direction of the main flow direction.In a further development of the invention, a seal receiving section of the filter insert frame runs around the outside of the filter body. In particular during the removal and the installation of the secondary filter insert, shear forces exerted on the seal are absorbed by the seal receiving portion.One embodiment provides that the bond comprises a polyurethane and is in particular foamed. In particular, the adhesion can partially penetrate the filter body and thus ensure a particularly firm adhesion between the filter body and the filter insert frame.In a further development of the invention, it can be provided that the filter insert frame has a grid covering the outflow surface on the outflow side. This increases the collapse strength of the secondary filter insert at high differential pressures. In particular, the grid can be formed integrally with the filter insert frame.The fifth object is achieved by a filter insert for a filter for filtering a fluid, in particular air, in particular for an internal combustion engine according to claim 45. Further embodiments of the invention are specified in the dependent claims.The filter insert according to the invention has a main inflow surface, an outflow surface and a main flow direction. Furthermore, the filter insert has a filter body, through which flow can take place along the main flow direction, and a filter insert frame carrying the filter body. The filter insert frame has a seal for separating a filter interior of a filter in the clean side and the raw side and also a grip region on the inflow side. The grip region is designed such that an inflow to the filter body via the grip region and a manual removal of the filter insert is possible. In this way, the area over which the filter body can be subjected to flow is enlarged. Since, as a rule, a possibility for manual handling of the filter insert is to be provided in any case, in particular during installation and removal of the filter insert, the pressure drop or pressure loss caused by the filter insert is significantly reduced by the design of the grip region for a flow of the fluid to be filtered.In a preferred further development of the invention, it is provided that a secondary inflow surface is provided laterally to the main inflow surface. This opens up a further inflow surface of the filter insert for the generally improved inflow situation of the filter insert and thus further reduces the pressure loss through the filter insert. In this case, it can be provided in particular that the grip region allows the filter body to flow laterally next to the main flow surface.The grip region is preferably designed as a recessed grip, and the recessed grip points toward the filter body. On the one hand, the recessed grip offers a particularly simple possibility of removing the filter insert from its inserted position. On the other hand, the shape of a trough enables a particularly turbulence-free inflow of the fluid to the filter body, in particular to the main inflow surface and the secondary inflow surface.In one embodiment of the invention, it is provided that the grip region essentially does not protrude beyond the inflow surface in the main flow direction. The filter body can likewise be of substantially cuboidal design.In the further embodiment, the filter body is designed as a filter bellows folded in a zigzag shape and, in particular, one of the end faces of the filter bellows folds (i.e. the side faces formed by the zigzag shape of the folded filter medium) points in the direction of the grip region. By the configuration according to the invention of the grip region which is open to this end side, the flowing fluid is fed to the end sides of the filter bellows folds. In the case of a one-sided sealing of the end faces only on the clean side of the folded filter medium, the end face partially remains open at the gaps between the folds which are not bonded on the raw side. Thus, the fluid can pass at the end side into the interior of the filter bellows without any flow around the filter body. In this way, in addition to the regular main inflow surface, which is formed by the folded edges, the end face of the filter bellows can serve as a secondary inflow surface and thus minimize the pressure loss.In a particularly preferred embodiment of the invention, the filter insert is designed as a secondary filter insert. Since in particular the installation space situated after the main filter insert is particularly narrow and does not always allow an inflow surface on the secondary filter insert which is equivalent to the entire outflow surface of the main filter insert to be realized, an additional secondary inflow surface is of particularly great importance for optimizing the entire filter system.In a further development of the invention, it is provided that the filter insert frame has a grid covering the outflow surface on the outflow side. In particular in the case of high pressure differences or in the case of a change of the main filter element during operation, a particularly high collapse pressure of a secondary filter insert is important. This is decisively improved by the provision of a downstream grid.The grid can preferably be formed integrally with the filter insert frame.The sixth object is achieved by a filter according to claim 55. Further embodiments of the invention are specified in the dependent claims.The filter according to the invention, in particular for internal combustion engines, for filtering a fluid, in particular air, has a filter housing with a raw-side region and a clean-side region. A main filter element can be inserted into the filter housing, which has a main filter element inflow surface, a main filter element flow direction, a main filter element outflow surface and a seal arranged on a sealing surface. For example, the main filter element can have a prismatic basic shape. In particular, a flow through the lateral surfaces can take place. The seal serves for the fluid-tight separation of the raw-side region of the filter housing from the clean-side region of the filter housing. Furthermore, the filter has a secondary filter element arranged downstream of the main filter element, having a secondary filter element inflow surface, a secondary filter element flow direction and a secondary filter element outflow surface. The sealing surface is arranged obliquely to the main flow direction of the main filter element. The oblique sealing surface opens up a space within the filter housing downstream of the main filter element, in which space the secondary filter element can be arranged on the one hand. At the same time, the sealing surface that is inclined with respect to the main flow direction already deflects the main flow direction in the filter housing. Thus, with a suitable attachment of an outflow opening to the filter housing, a deflection of the fluid stream in the desired direction can take place. It is possible to dispense with otherwise necessary elbows or the like downstream of the housing.The sealing surface and the main flow direction can in particular enclose an angle which is between 85° and 10°. Within this angular range, a noticeable deflection of the fluid stream occurs.One embodiment of the invention provides that the sealing surface is curved and lies in particular on a cylinder jacket surface. By virtue of a concave configuration of the sealing surface as seen from the main filter element, the installation space available for the main filter element can be optimized and, given a suitable selection of the radius of curvature, offers sufficient space for a secondary element. At the same time, the curvature of the sealing surface makes it particularly easy to define the outflow direction of the filter housing depending on the position of the outflow opening. Preferably, the axis of the cylinder of the cylinder jacket surface lies perpendicular to the main filter element flow direction and perpendicular to the secondary filter element flow direction.Alternatively, the sealing surface can lie in one plane.A preferred embodiment of the invention provides that the sealing surface and the main filter element outflow surface extend parallel. This results in a clearly defined separating plane between the raw side and the clean side of the filter housing. At the same time, with a curved design of the sealing surface, a construction space-optimized configuration of the filter interior and thus of the entire filter results.It is preferably provided that the secondary element inflow surface extends parallel to and spaced apart from the sealing surface. It is thus ensured that when the secondary filter element is changed, the clean side of the filter housing is not soiled. In the case of a curved design of the sealing surface, a likewise curved secondary element inflow surface results.In a preferred embodiment of the invention, the basic shape of the secondary filter element is a cuboid. This enables a simple construction of the secondary element, for example from a straight folded flat element, in which the folding edges on the inflow side and outflow side each form planes which are preferably arranged parallel to one another at a distance defined by the fold height.Alternatively, the basic shape of the secondary element can be a prism with one or more curved lateral surfaces, such as a hollow cylindrical lateral portion. This can be realized, for example, by a curved flat bellows. This shape offers the possibility of adapting the secondary filter element to a curved main filter element outflow surface and thus further optimizing the installation space.In a preferred embodiment of the invention, the basic shape of the main filter element is a prism. In particular, the base surface and the top surface of the prism can be a quadrilateral or a pentagonal. The quadrilateral or pentagonal can have two or three right angles, an acute and an obtuse angle. A preferred embodiment of the invention provides that a lateral side of the prism is convexly curved when viewed from the outside, so that a main filter element outflow surface is produced which is designed, for example, as a lateral lateral surface.An advantageous embodiment of the invention provides that the main filter element is a bellows with at least two different fold depths. By means of two different fold depths, the main filter element outflow surface inclined with respect to the main flow direction of the main filter element can be realized at the fold end sides. Alternatively, by means of a continuously increasing fold height, the main filter element outflow surface inclined with respect to the outflow direction of the main filter element can be realized at the fold edges. The terms pleat depth and pleat height are used interchangeably herein.An advantageous embodiment of the invention provides that the filter housing has an inflow direction, an outflow direction and an outflow region with an outflow opening. An outflow connector can be fastened to the outflow region, wherein the outflow region has a fastening surface for the outflow connector and the fastening surface encloses an angle of 45° with the main filter element flow direction. The fastening surface inclined at 45° to the main flow direction is particularly preferably arranged on the filter housing such that it lies within the filter housing, as seen in the main filter element flow direction, i.e. it does not project beyond the filter housing. At the same time, this fastening surface is situated perpendicular to the main flow direction of the main filter element, i.e., below the main filter element, for example, as viewed in an insertion direction of the main filter element. An outflow connection attached to this fastening surface can now distribute the outflowing filtered fluid in any desired directions in a comparatively simple manner.A particularly preferred embodiment of the invention provides that the outflow connection piece is shaped such that a deflection of the flow direction by 45° results. In this way, only the orientation of the outflow connection piece at the outflow region, in particular at the fastening surface, is relevant with respect to the ultimately resulting outflow direction. This makes it possible in a particularly advantageous manner to define the outflow direction of the filtered fluid using a single component, namely the outflow connection piece. By suitable orientation of the outflow connection piece on the fastening surface, the final outflow direction of the filter housing is obtained.A preferred further development of the invention provides that the outflow connector has a rotationally symmetrical fastening region for fastening to the fastening surface of the filter housing. Thus, by rotating the outflow connection piece, the final fixing of the outflow direction of the entire filter housing can be fixed. Thus, between the inflow direction of the filter housing and the outflow direction of the filter housing, an angular range between 0° and 90° results with one and the same components.In the same way, it can be defined that the outflow direction and the fastening surface enclose an angle of 45°.An alternative further development of the inventive concept provides that the fastening surface lies on a cylinder jacket surface. The axis of the cylinder is preferably perpendicular to the main flow direction of the main filter element. A fastening surface curved in this way is preferably combined with a correspondingly curved fastening region of an outflow connector. The position of the outflow connection piece at the outflow region then defines the outflow direction of the filter housing.Preferably, the attachment surface and the secondary element outflow surface extend parallel. This enables an extremely high integration and thus installation space optimization.According to the invention, in one embodiment it can be provided that the main filter element can be inserted into and removed from the filter housing along an insertion axis, wherein the insertion axis encloses an angle between 90° with the main flow direction and the angle which the sealing surface and the main flow direction enclose. According to this embodiment, the filter housing has a cover which is designed such that, in the state in which it closes the filter housing, it exerts a force on the main filter element in the direction of the sealing surface. Due to the oblique position of the sealing surface, this force is at least partially converted into an axial force, i.e. into a force which acts in the direction of the main flow direction. This produces a force which presses the main filter element with its seal attached to the sealing surface against a main filter element seat on the filter housing.Brief Description of the DrawingsThe invention will be explained in more detail with reference to the drawings. The following are shown: FIG. 1 shows a perspective sectional view of an embodiment of a filter according to the invention with inserted main filter insert and secondary filter insert; FIG. 2 shows the filter of FIG. 1 without the secondary filter insert inserted; FIG. 3 shows the filter of FIG. 1 without inserted main filter insert; FIG. 4 shows the filter of FIG. 1 in a cross-sectional view; FIG. 5 shows a perspective external view of the filter according to the invention from FIG. 1 ; FIG. 6 shows a perspective view of a secondary filter insert according to the invention with a filter body; FIG. 6a is a perspective view of an alternative secondary filter cartridge filter body according to the invention; FIGS. 7, 8 are perspective views of the secondary filter insert of FIG. 6 without a filter body; FIG. 9 is a perspective sectional view of the filter of FIG. 6 ; FIG. 10 is a sectional view of the filter of FIG. 7; FIG. 11 is a front perspective view of a main filter cartridge according to the invention; FIG. 12 is a rear perspective view of the main filter cartridge of FIG. 11 ; FIG. 13 is a perspective sectional view of the main filter insert of FIG. 11 ; FIG. 14 is a perspective rear view of the main filter insert of FIG. 11 without edge protection; FIGS. 15, 16 show perspective external views of the filter of FIG. 5 with different positions of the outflow connector; FIG. 17 is a side view of the filter of FIG. 5; FIG. 18 is a side view of the filter of FIG. 15 ; and FIG. 19 is a side view of the filter of FIG. 16.Embodiment(s) of the InventionReferring now to Figures 1 to 5, an embodiment of a filter 10 according to the invention will be described. Such a filter 10 can be used, for example, in an air intake tract of a construction machine or agricultural machine, of a compressor or of another device having an internal combustion engine for filtering a fluid, in particular air. The filter 10 has a filter housing 12 which can be roughly divided into a raw-side region 14 and a clean-side region 16.The filter 100 is flown through along a main inflow direction X. On an upstream side 16, the fluid to be filtered impinges on a coarse or pre-separator module 18, which is designed as a cyclone block in the present case. In the cyclone block 18 a plurality of individual pre-separator cells 20 are connected in parallel in a so-called multi-cyclone block. Pre-separated dust and / or water in the cyclone block 18 is removed from the filter housing 12 through a discharge connection 22.After the cyclone block 18, the fluid to be filtered reaches the main filter insert 100. The main filter insert 100 is designed prismatically in the present case. An inflow surface 110 of the main filter insert 100 is not parallel to an outflow surface 112 of the main filter insert 100. Rather, the inflow surface 110 and the outflow surface 112 form an angle. In the present case, the inflow surface 110 of the main filter insert 100 is smaller with respect to its desired surface than the outflow surface 112 of the main filter insert 100. On the outflow side of the main filter insert 100, a secondary filter insert 200 is provided in the filter housing 12. A main inflow surface 210 of the secondary filter element 200 is aligned with the outflow surface 112 of the main filter insert 100 and is arranged in particular parallel thereto. In this embodiment, an outflow surface 212 is oriented parallel to the main inflow surface 210 of the secondary filter insert 200. Due to the inclination of the outflow surface 112 of the main filter insert 100, a deflection of the main flow direction X takes place already when the fluid flows from the main filter insert 100, but also when the fluid flows from the secondary filter insert 200. Due to the outflow geometry of the filter housing 12 in the outflow region 24, the flowing fluid is directed around the outflow direction Y and to an outflow connector 26. In the present case, the main outflow direction Y is substantially perpendicular to the main inflow direction X. However, other outflow directions are also conceivable. This is explained in more detail in particular in connection with FIGS. 15-19.The main filter insert 100 has a main filter insert inflow surface 110, a main filter insert flow direction X 1, a main filter insert outflow surface 112 and a seal 116 arranged on a sealing surface 114 for the fluid-tight separation of the raw-side region 14 and the clean-side region 16 of the filter housing 12. Downstream of the main filter insert 100, a secondary filter insert 200 is arranged with a secondary filter insert inflow surface 210, a secondary filter insert flow direction Y 1 and a secondary filter insert outflow surface 212. The sealing surface 114 of the main filter insert 100 is arranged obliquely to the main flow direction Y 1 of the main filter insert 100. In particular, the sealing surface 114 is arranged at an angle α, which is preferably between 5° and 45° (see FIG. 4 ), In particular, the angle is 24°±10° and 24°±5°. In the present embodiment, the angle α is 24° (see FIG. 4 ).The secondary filter insert inflow surface 210 extends substantially parallel to and spaced apart from the sealing surface 114 of the main filter insert 100. The distance is less than 2 cm, in the present embodiment the distance is 1 cm.FIGS. 11-14 show the main filter cartridge 100. The main filter insert 100 has an inflow surface 110, an outflow surface 112. The main filter insert 100 is flowed against along a main inflow direction X and flowed through along a main inflow direction X 1. The main filter cartridge 100 includes a cartridge frame 118 that receives a filter body 120. The filter body 120 is designed as a bellows in the present case. Upstream folded edges 122 are opposite downstream folded edges 124. Upstream folded edges 122 and downstream folded edges 124 are parallel and substantially perpendicular to the main flow direction X 1 and substantially horizontal in FIGS. 11 to 14. This orientation of the folded edges 122, 124 allows a variation of the fold depth in the direction of an insertion direction Z. Along the insertion direction Z, the main filter insert 100 can be inserted into the filter housing 12 of the filter 10. In the present exemplary embodiment, the fold height decreases along the insertion direction Z. This causes the inflow surface 110 to tilt relative to the outflow surface 112.In the region of the outflow surface 110, the filter frame 118 has a sealing surface 114, along which a circumferential seal 116 is provided. The seal serves to separate the raw side region 14 from the clean side region 16 in the filter housing 12 of the filter 10 when the main filter insert 100 is inserted into the filter 10. The seal 112 has a substantially U-shape in cross section.For reinforcement and better mechanical connection of the seal 116 to the filter frame 118, a web 126 is provided, which engages in the U-shape of the seal 116. At the same time, the seal 116 can contact or penetrate the filter body 120, so that at the same time an adhesion of the filter body 120 to the filter insert frame 118 and a fluid-tight seal between the filter body 120 and the filter insert frame 118 are produced.Furthermore, the seal 116 has a spacing structure which is designed in the present case as supporting knobs 128. The support knobs 128 are part of the sealing material of the seal 116. As can be seen from the cross-sectional view of FIG. 4, the support knobs 128 contact the secondary filter insert 200, in particular a secondary filter insert frame, when the main filter insert 100 and the secondary filter insert 200 are inserted in the filter housing 12 of the filter 10. In this state, the secondary filter insert 200 cannot move out of a sealing seat in the filter housing 12 even in the event of a vibration excitation, which can be transmitted, for example, through the filter housing 12. In addition, the support knobs 128 ensure that the secondary filter insert 200 is seated in the correct position in the filter housing 12 after the installation of the main filter insert 100 and the closing of the cover 13.The support knobs 128 are arranged multiple times along the seal 116 on the side facing the outflow surface 112. For example, they may be integrally formed with the seal 116 during manufacture of the seal 116.The seal 116 is located on the outflow surface 112 of the main filter insert 100 and acts in a direction which is perpendicular to the outflow surface 112, that is to say substantially axially along the main throughflow direction X 1.The main filter insert 100 has on its inflow side 110 an edge guard 130 running around the outside of the filter frame 118. The edge guard 130 is designed such that, when the main filter insert 100 is knocking out, for example for cleaning purposes, impacts against the filter frame 118 can be absorbed and at least partially sprung. Thus, a breakage of the filter frame 118 or another damage of the filter insert 100, for example of the filter body 120, can be avoided. The edge guard 130 wraps around the upstream edge of the filter element 118. Individual interruptions, such as the notches 134, may be provided. The notches 134 are formed during the production of the edge guard 130. Here, the filter frame 118 together with the filter body 120 lies in a casting shell. Webs thereby keep a distance between the casting shell base and the filter body 118 and thereby leave the notches 134 during the casting process.Recesses 136 are provided on the upstream edge 132. The recesses 136 pass through the side walls of the filter frame 118 and thus extend perpendicular to the main flow direction X 1. During the already mentioned casting process, the casting material for the edge guard 130 penetrates the recesses 136, contacts the inner walls of the filter insert frame 118 and in particular the filter body 120. This results in a fluid-tight seal between the filter body 120 and the filter insert frame 118 and at the same time an adhesion of the two components. The edge protection 130 is thus produced in one piece with the adhesion between the filter body 120 and the filter insert frame 118 and a likewise necessary seal between the two components. The edge guard 130 may be made of, for example, a foamable polyurethane. However, silicone-based material systems are also conceivable.The filter insert 100 has a handle 138. The handle 138 interacts with the cover 13 of the filter 10 and ensures a secure seating of the main filter insert 100 in the filter housing 12 and at the same time exerts a pressure on the seal 116 directed axially in the direction of the main flow direction X 1 and thus ensures a fixed sealing seat of the main filter insert 100 in the filter housing 12.FIGS. 6-10 show an embodiment of a secondary filter cartridge 200. The secondary filter insert 200 has a main inflow surface 210, an outflow surface 212 and a main throughflow direction Y 1. The secondary filter insert 200 further comprises a filter body 214 which is supported by a filter insert frame 216. On the inflow side, the filter insert frame 216 terminates with a frame region 218 surrounding the filter body 214 substantially flush with the filter body 214. The frame region 218 can serve, for example, as an abutment for the supporting knobs 128 of the main filter insert 100 in the inserted state of both filter inserts 100, 200.In the present embodiment, the filter body 214 is substantially rectangular parallelepiped. However, other basic shapes such as a prism are also conceivable. On the outflow side, i.e. in the region of the outflow surface 212, the filter insert frame 216 is provided with a lattice structure 220. The grid structure 220 at least partially covers the outflow surface 212. In the case of a high differential pressure between the inflow side 210 and the outflow side 212, the lattice structure 220 prevents undesired bending or even dropping of the filter body 214.On a narrow side of the rectangular filter body 214, the filter insert frame 216 is provided with a recessed grip 222. In order to enable a comfortable grip in the grip recess 222 for the hand of a person who wishes to change the secondary filter insert 200, the frame region 218 is widened in the region of the grip recess 222 to form a grip web 224. The width of the grip web 224 is selected such that a fluid leaving the main filter insert outflow surface 112 can flow directly to the filter body 214, in particular on the side facing the grip recess 222. This can also be clearly seen in particular from the cross-sectional view of FIG. 4. Also, from the uppermost edge 113 of the main filter element outflow surface 112, an emerging fluid can flow directly to the filter body 214 of the secondary filter insert 200. In this case, the fluid can enter the filter body 214, in particular via the secondary inflow surface 211.In this exemplary embodiment, the filter body 214 is designed as a filter bellows. The folded edges extend parallel to the longitudinal axis of the secondary filter insert 200 so that the end sides of the folds form the secondary inflow surface 211. The fold edges of the folds form the main upstream surface 210 and the downstream surface 212. The combination of the grip recess 222 and the filter bellows 214 that can be flowed laterally on via the secondary inflow surface 211 enables the pressure losses at the secondary filter insert 200 to be reduced, since the secondary filter insert 200 is significantly better adapted to the flow guidance from the main filter insert 100 to the outflow connection piece in the filter housing 12. At the same time, the grid structure 220 on the outflow side 212 increases the collapse resistance of the secondary filter insert 200. Furthermore, the integrated handle on the recessed grip 222 makes it possible to easily disassemble the filter insert 200.The secondary filter insert 200 has a filter frame 216, which provides a groove 226 circumferentially around the downstream edge of the filter body 214. At the same time, a web 228 is provided on the side of the filter insert frame 216 facing the grip recess 222. The groove 226 serves as a casting mold for circumferential adhesion and sealing of the filter body 214 to the filter insert frame 216. The sealing and adhesion is effected by a sealing material 230 (see FIG. 9 ). The sealing material 230 may be, for example, a foaming polyurethane. However, silicone-based material systems are also conceivable.The groove 226 and additionally the web 228 ensure good mechanical coupling of the sealing material 230 to the filter insert frame 216. This embodiment also has the advantage that after the introduction of the sealing material 230 into the groove 226 and the insertion of the filter body 214 into the filter insert frame 216 and subsequent foaming and curing, no further processing steps, such as cutting of the sealing material 230, are necessary. Excess material can be partially absorbed by the filter body 214 or can pass into the intermediate region between the filter body 214 and the filter insert frame 216, without this being disadvantageous.The depth of the groove 226 extends substantially along the main flow direction Y 1 of the secondary filter insert 200. The outflow-side grid structure 222 can be formed integrally with the filter insert frame 216.On its inflow-side periphery, the filter insert frame 216 has a seal receiving groove 232. In this seal receiving groove 232, a seal 234 made of, for example, a sponge rubber may be inserted. The seal 234 thus acts radially, i.e. perpendicularly to the main throughflow direction Y 1 of the secondary filter insert 200.FIGS. 15-19 show the filter 10 with different orientations of the outflow connector 26; the filter housing 12 of the filter 10 has a fastening region 25 in the outflow region 24. The fastening region 25 encloses an angle of approximately 45° with the main inflow direction X of the filter housing 12. The outflow connector 26 can be fastened to the fastening region 25. The outflow connector 26 is shaped such that a fluid flowing through the outflow connector 26 experiences a deflection of 45°. The outflow connector 46 can be rotatably attached to the fastening surface 25 before a final fastening. It is therefore only possible to define the final deflection direction or outflow direction Y of the filter 10 at a very late point in time during the production of the filter 10. In the geometry shown in this embodiment, inline flow (FIGS. 15, 18 ), a deflection by 90° (FIG. 17 ) and angular ranges located therebetween are possible. In the case of the angular ranges between the extreme angular ranges, a lateral deflection additionally takes place.

Claims

Filter (10) for filtering air for an internal combustion engine, having a filter housing (12) into which a main filter insert (100) and a secondary filter insert (200) are inserted, wherein the main filter insert (100) has an inflow surface (110), an outflow surface (112) and a main flow direction (X1) perpendicular to the inflow surface (110), a filter body (120) and a filter insert frame (118) carrying the filter body (120), and the secondary filter insert (200) is arranged downstream of the main filter insert (100), wherein the filter insert frame (118) has, in the region of the outflow surface (112), a seal (116) for separating the filter housing (12) in the clean side and the raw side and a spacing structure (128) which fixes the spacing between the filter insert frame (118) and the secondary filter insert (200), wherein the outflow surface (112) and a sealing surface (114) of the seal (116) form an angle (α) of 24°±10° with the inflow surface (110).The filter of claim 1, wherein the downstream surface (112) and the sealing surface (114) of the seal (116) form an angle (α) of 24°±5° with the upstream surface (110).Filter according to claim 1 or 2, wherein the filter housing (12) has an insertion direction (Z) which is substantially perpendicular to the main flow direction (X1).The filter according to any one of the preceding claims, wherein in the inserted state of the main filter insert (100) and the secondary filter insert (200), the spacer structure (128) of the main filter insert (100) contacts the seal or the secondary filter insert frame (218) of the secondary filter insert (200).Use of a main filter insert (100) in a filter (10) according to one of the preceding claims, the main filter insert (100) having an inflow surface (110), an outflow surface (112) and a main flow direction (X), a filter body (120), a filter insert frame (118) carrying the filter body (120), wherein the filter insert frame (118) has, in the region of the outflow surface (112), a seal (116) for separating a filter interior in the clean side and the raw side and a spacer structure (128) for defining a distance between the filter insert frame (118) and the further secondary filter insert (200) which can be arranged downstream in the main flow direction (X), wherein the outflow surface (112) and a sealing surface (114) of the seal (116) form an angle (α) of 24°±10° with the inflow surface (110).Use according to Claim 5, wherein the spacer structure (128) is arranged within the seal (116), in particular multiple times along the seal (116) and in particular on the periphery of the outflow surface (112).Use according to either of Claims 5 and 6, wherein the outflow surface (112) and the sealing surface (114) of the seal (116) form an angle (α) of 24°±5° with the inflow surface (110).Use according to one of the preceding claims 5 to 7, wherein the spacer structure (128) is formed integrally with the seal (116), in particular is formed into the seal.Use according to one of the preceding claims 5 to 8, wherein the spacer structure (128) is designed to exert a force on the secondary filter insert, which can be arranged downstream in the main flow direction (X), in the installed state of the filter insert (100), wherein the force presses the further filter insert (200) into its installed position.Use according to any one of the preceding claims 5 to 9, wherein the seal (116) acts axially in the direction of the main flow direction (X).Use according to one of the preceding claims 5 to 10, wherein the filter body (120) is designed as a filter bellows, preferably with a variable fold height.Use of a secondary filter insert (200) in a filter (10) according to any one of claims 1 - 4, wherein the secondary filter insert (200) is designed to be inserted into the filter (10) downstream of the main filter insert (100) in such a way that in the inserted state of the main filter insert (100) and the secondary filter insert (200) the spacer structure (128) of the main filter insert (100) contacts a seal (234) or a secondary filter insert frame (216) of the secondary filter insert (200), with an inflow surface (210), an outflow surface (212) and a main flow direction (Y1), a filter body (214), which can be flown through along the main flow direction (Y1), a filter insert frame (216) carrying the filter body (214), wherein the filter insert frame (216) has the seal (234) for separating a filter interior of a filter (10) in the clean side and the raw side and an adhesive bond (230) between the filter body (214) and the filter insert frame (216).Use according to claim 12, wherein the seal (234) is designed to act radially with respect to the main flow direction (Y1) and in particular runs around the secondary filter insert (200) substantially perpendicularly with respect to the main flow direction (Y1).Use according to either of Claims 12 and 13, wherein a carrier section (226) of the filter insert frame (216) runs around the filter body (214) and the carrier section has an inner edge, in particular a groove (226), on the inner side for receiving an adhesive material (230) of the adhesive bond.Use according to claim 14, wherein the depth of the groove (226) is in the direction of the main flow direction (Y1).Use according to one of the preceding claims 12 to 15, wherein a seal receiving section (232) of the filter insert frame (216) runs around the outside of the filter body (214).Use according to any of the preceding claims 12 to 16, wherein the bond (230) comprises a polyurethane and is in particular foamed.Use according to one of the preceding claims 12 to 17, wherein the adhesive bond (230) partially penetrates the filter body (214).Use according to any one of the preceding claims 12 to 18, wherein the seal (234) comprises a moss rubber.Use according to one of the preceding claims 12 to 19, wherein the filter insert frame (216) has, on the outflow side, a grid (220) covering the outflow surface (212).

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