Filter system and filter element for a filter system

Abstract

A filter element (10) comprising a closed filter body (12) elongated along a longitudinal axis (L) and a closed end plate (20) firmly connected thereto, to which the filter body (12) is tightly connected with its end face (50), wherein the end plate (20) has a fixing position (32) for an axially outwardly projecting support structure (40), wherein the fixing position (32) is arranged in a bulge (30) of the end plate (20) and the fixing position (32) is arranged outwardly with respect to a radial position within an outer skin of the filter body (12) and axially in front of the end face (50) of the filter body (12), and the bulge (30) extends a space defined by an inner side of the filter body (12), wherein the bulge (30) has through openings (34) in the axial direction.

Description

Technical FieldThe invention relates to a filter system, in particular for use as an air filter of an internal combustion engine, and to a filter element for installation in such a filter system.Prior ArtWO 2009 / 047196 A1 discloses a filter system for internal combustion engines having a filter element. This filter system serves in particular for filtering the intake air of an internal combustion engine and comprises a housing and a cover for receiving the filter element, in which, by the design of the seals of the filter element with two annular bead-shaped arrangements and a sealing groove lying therebetween, it is ensured that, on the one hand, a sealing effect and, on the other hand, an axial support of the filter element in a housing is achieved. Particularly when using plastic for sealing on vibration-loaded elements, a design is required which works reliably even in the event of extreme temperature fluctuations.DE 20 2013 011 841 U1 discloses a filter system for filtering a fluid, comprising a filter element, a filter housing with a cover, a sealing device arranged on the filter element for separating a raw side of the filter system from a clean side, a coupling device consisting of at least two coupling parts for coupling the filter element to the cover, wherein the coupling parts comprise a coupling element and a coupling receptacle, wherein the coupling device is a quick coupling device and the sealing device is arranged in its sealing position in an end position of coupled coupling element and coupling receptacle.Basically, it is provided that the filter elements of air filters are replaced after a certain operating time. Depending on the dust incidence, the service life of an air filter can be a few days (construction machines) up to several months. In this case, the secondary filter element, which is arranged on the clean air side, usually remains in the filter system. However, if the secondary filter element is also heavily loaded with dirt, it must also be replaced, since otherwise the air throughput is reduced too much. The reliable and process-safe sealing of the filter element and secondary filter element in a housing is particularly important in order to protect the intake tract of a subsequent internal combustion engine from penetrating dirt.Depending on the intended use of the filter system, it may be advantageous to provide only one primary filter element or additionally a secondary filter element.Disclosure of the InventionAn object of the invention is to provide a filter element which can be used in a filter system optionally with or without a secondary filter element, which allows a reliable seal between the region of the unfiltered and the region of the filtered medium and allows a stable installation position in a housing of a filter system.A further object of the invention is to provide a filter system with such a filter element.The aforementioned objects are achieved according to one aspect of the invention in a filter element and according to another aspect in a filter system with an exchangeable filter element, in which the filter body is tightly connected with its end face to an in particular closed end plate, wherein the end plate has a fixing position for an axially outwardly projecting support structure, wherein the fixing position is arranged in a bulge of the end plate and the fixing position is arranged in relation to a radial position within an outer side of the filter body and axially upstream of the end face of the filter body, and wherein the bulge extends a space defined by an inner side of the filter body.Advantageous embodiments and advantages of the invention are evident from the further claims, the description and the drawings.A filter element is proposed, comprising a filter body which is elongate along a longitudinal axis and is closed in an annular manner, and a closed end plate which is fixedly connected thereto and to which the filter body is connected in a sealing manner by its end face, wherein the end plate has a fixing position for a supporting structure which projects axially outwards, wherein the fixing position is arranged in a bulge of the end plate and the fixing position is arranged in front of the end face of the filter body axially with respect to a radial position within an outer skin of the filter body and wherein the bulge extends a space defined by an inner side of the filter body.Because the space defined by an inner side of the filter body is extended by the bulge, the space extended in this way protrudes beyond the end face of the filter body of the filter element and preferably beyond the outer edge of the end plate. Thus, a possible secondary element can be longer and / or the space required for any handle arranged on the secondary element can be created.Advantageously, the end plate can both support a sealing function of the filter body and a supporting function by axially bracing the filter element in a housing by means of the supporting structure. The support structure allows a reliable introduction of force from a housing cover into the end plate. The spatially separated sealing and supporting regions allow a flexible filter element construction oriented to installation space.Due to the arrangement of the sealing region and the supporting structure, the surfaces of the sealing region and the supporting structure can be located axially on different planes, which is not possible with a continuously foamed polyurethane end plate. The sealing region is formed in particular by an adhesive region in the form of a sealing adhesive connection. Because the surfaces of the foamed volumes can be arranged on different planes, in particular the inner surface of the supporting structure can be axially further away from the air outlet than the surface of the bond region or the end face of the filter body.The support structure can in particular have support knobs protruding axially outwards, which, when installed in a housing, allow stable bracing in the axial direction in the housing, which bracing is resistant to vibrations. In this way, the filter element is braced axially against the cover and thus against the housing via the closed end disk and is thereby firmly mounted on the end face, the cover-side end of the filter element.Advantageously, the closed end disk can be formed as a molded part from a solid plastic, for example by injection molding. Alternatively, the end disk can be designed as a two-component end disk with a hard injection-molded part and an elastic part, e.g. polyurethane or a thermoplastic elastomer.On the side of the filter body opposite the closed end plate, an open end plate can be provided, which is formed in particular from polyurethane and which permits a radial sealing of the filter body. Advantageously, supporting knobs protruding in the axial direction can likewise be provided there.Advantageously, the open end plate can have a radial seal with respect to a housing. This has the advantage that, in addition to a good seal and thus a secure filtering effect, the radial seal and the axial bracing of the supporting knobs in the cover allow a radial guidance of the filter element in the housing to be effected and thus a very stable mounting of the filter element in the housing is produced.The filter body can consist, for example, of a star-folded filter bellows which is embodied in a ring-shaped closed manner. The folding can be produced, for example, by blade folding, for longer filter bodies, or rotational folding. The filter bellows can consist, for example, of paper or of cellulose or of a mixed fiber of plastic and cellulose. The filter bellows can also be designed with a smooth surface, rolled and / or surface designed in different stamping shapes for stiffening and / or creating cavities for dust deposition. The filter bellows may have a coating and / or impregnation to reject moisture. Alternatively, it can also be coated with nanofibers. The filter body can furthermore be structurally reinforced with a thread winding. A wound filter body with one or more layers is also conceivable.The bulge in the axial direction has through-openings. In particular, the through-openings can be traversed by the supporting structure. The support structure can engage through the through-openings in a positive-locking manner and thus form a particularly stable connection with the end plate.According to a favorable embodiment, the support structure can be formed from an elastomer, in particular polyurethane. Polyurethane foam can easily penetrate the through openings during the production of the supporting structure.According to a favorable embodiment, the filter body can be foamed on the end plate on its end face with an elastomer, in particular polyurethane. The support structure with the sealing adhesive connection on the filter body can then be produced in a common casting shell. Alternatively, the filter body can be glued to the end plate on its end face with an adhesive. Alternatively, the filter body can be welded to the end plate on its end face. A flexible and need-based production of the filter element is possible.According to a favorable embodiment, the filter body can be conically shaped and have a larger outer diameter on the closed end plate than on its opposite end face. This allows a favorable flow distribution along the filter body.According to a favorable embodiment, the bulge can be hollow cylindrical. This provides installation space for mounting a secondary filter element within the filter element, in particular within a central tube which can engage in the bulge.According to a favorable embodiment, the bulge can be designed to receive a secondary filter element. In particular, a support region for the secondary filter element can be provided in the bulge of the end plate. The filter element and the secondary filter element can be changed independently of each other.According to a favorable embodiment, the bulge can be arranged within a clear width of the filter body. A central tube can be provided which engages into the bulge and in which a secondary filter element can be arranged. The end plate can advantageously also have an insertion bevel on the inside in the region in which the central tube engages, which tapers the filter element when mounted on the central tube. In one embodiment, the axially inner boundary surface of the support structure can abut on the central tube, so that the support structure can be braced between the housing cover and the central tube, so that no or less axial bracing force is transmitted via the filter bellows in the direction of the other end plate.According to a further aspect of the invention, a filter system is proposed, comprising a housing having a longitudinal axis, a cover which closes the housing on an end face, an inlet connection arranged on the housing for supplying a medium to be filtered and an outlet connection arranged on the housing for discharging the filtered medium, and an exchangeable filter element which has a filter body which is elongate along a longitudinal axis and is closed in an annular manner and a closed end plate which is fixedly connected thereto and to which the filter body is connected in a sealing manner by its end face, wherein the end plate has a fixing position for a supporting structure which projects axially outwards, wherein the fixing position is arranged in a bulge of the end plate and the fixing position is arranged upstream of the front side of the filter body axially with respect to a radial position within an outer skin of the filter body and wherein the bulge extends a space defined by an inner side of the filter body.Because the space defined by an inner side of the filter body is extended by the bulge, the space extended in this way protrudes beyond the end face of the filter body of the filter element and preferably beyond the outer edge of the end plate. Thus, a possible secondary element can be longer and / or the space required for any handle arranged on the secondary element can be created.According to a favorable embodiment, a middle tube fixed to the housing can be provided. This can be latched to the housing.On the side of the filter body opposite the closed end plate, an open end plate can be provided, which can be formed in particular from polyurethane and which permits a radial sealing of the filter body. Advantageously, support knobs protruding in the axial direction can be provided there. The closed end disk can have support knobs for axial and / or radial force transmission between the cover and the second end disk. In this way, the force exerted on the end disk via the closing of the cover can be passed through the end disk and introduced into the central tube, resulting in a fixed mounting of the filter element. In particular, the end plate can also have an insertion bevel on the inside in the region in which the central tube engages, which tapers the filter element during assembly on the central tube. Optionally, the axially inner boundary surface of the support structure can abut the central tube, so that the support structure can be braced between the housing cover and the central tube, so that no or less axial bracing force is transmitted via the filter bellows in the direction of the opposite open end disk.Advantageously, the closed end disk can also have support knobs for axial and / or radial force transmission between the cover and a secondary filter element arranged within the filter element. In this way, the force exerted on the end disk via the closing of the cover can be passed through the latter and introduced into the secondary filter element, as a result of which the latter can in turn be pressed firmly into its housing seat. This allows a firm mounting of the secondary filter element and at the same time also good sealing between unfiltered and filtered areas of the filter system.In a preferred embodiment, the sealing region of the open end plate of one or both filter elements toward the housing is designed as described in WO 2012 / 172019 A1 or US 2014 / 0102058 A1. The contents of both applications are hereby expressly referred to and their disclosure fully incorporated into this application.It is advantageous to use a filter system as an air filter, in particular as an air filter in compressors, agricultural machines or other devices with internal combustion engines.Brief Description of the DrawingsFurther advantages are evident from the following description of the drawings. Exemplary embodiments of the invention are illustrated in the drawings. The drawings, specification and claims contain numerous features in combination. The skilled person will expediently also consider the features individually and summarize them to form meaningful further combinations.The following are shown by way of example: FIG. 1 shows a perspective view of a filter system according to an exemplary embodiment of the invention with a radially arranged inlet connection piece and a central outlet connection piece according to an exemplary embodiment of the invention; FIG. 2 is a quarter-sectional perspective view of a filter element according to an embodiment of the invention; FIG. 3 shows a detail of the filter element from FIG. 2 without a supporting structure on the end plate and a sealing region in the form of a sealing adhesive region on the filter element; FIG. 4 shows a longitudinal section through a filter system with a primary filter element and a secondary filter element according to an exemplary embodiment of the invention; and FIG. 5 shows a sectional illustration of a detail of the filter system from FIG. 4.Embodiments of the InventionIn the figures, identical or similar components are denoted by identical reference numerals. The figures merely show examples and should not be understood as limiting.FIG. 1 shows a perspective view of a filter system 100 according to an exemplary embodiment of the invention with a radially arranged inlet connection piece 102 and a central outlet connection piece 104. A round filter construction is shown, which consists of a housing 108 which is closed on one end side by a cover 110. In the case of an air filter system, dust-laden air flows into the inlet connector 102, which is arranged, for example, radially with respect to the air filter element installed on the inside. The cleaned air can be discharged from the housing 108 via the central outlet connection 104.The inlet connection piece 104 can be welded with its collar 106 to the previously perforated housing 108 in any angular position.FIGS. 2 and 3 show a perspective view, as a quarter section, of a filter element 10 according to an exemplary embodiment of the invention, wherein FIG. 3 shows a detail of the filter element 10 from FIG. 2 with omission of the supporting structure 40 and sealing region in the form of a sealing adhesive connection 52.FIG. 2 shows the filter element 10, which comprises a closed filter body 12 elongated along a longitudinal axis L and a closed end plate 20 firmly connected thereto. The filter body 12 is tightly connected with its end face 50 to the closed end plate 20. The end face 50 of the filter body 12 engages in a radially outer groove between a downwardly bent edge 38 of the end plate 20 and a radially inner collar 26 of the end plate 20. The sealing adhesive connection 52 is arranged on the filter body 12 in that, for example, polyurethane as a sealing and adhesive fills the groove, partially penetrates the end face 50 and connects the latter tightly and firmly to the end plate 20. Alternatively, the connection can be produced by means of an adhesive or by welding the filter body 12 to the end plate 20. A small bead 36 is arranged in the groove, which bead spaces the end face 50 from the groove base, so that a sufficient amount of sealant can pass between the end face 50 and the groove base.The closed end plate 20 has a fixing position 32 for an axially outwardly protruding support structure 40, wherein the fixing position 32 is arranged in a bulge 30 of the end plate 20 axially outwardly upstream of the end face 50 of the filter body 12. In relation to a radial position, the bulge 30 is positioned within an outer skin of the filter body 12 and in particular within the inner diameter of the filter body 12. As can be seen in FIG. 3, the bulge 30 has through-openings 34 at the fixing position 32. As a result, the support structure 40 can be connected in a positive-locking manner to the end plate 20 by the support material passing through the through-openings 34, for example polyurethane (also referred to as PUR) foaming around the through-openings 34 during the production of the support structure 40. This produces a firm, positive connection between PUR and the molded part (end plate 20), and both PUR regions can be produced from the same side, i.e. the liquid polyurethane can be metered in from the same side.The through-openings 34 form a groove bottom of an axially inner groove between the inner collar 26 and a radially inner collar 28. The collar 26 has a small shoulder 27 in the region of the groove with the through-openings 34, so that the supporting material, e.g. polyurethane, can additionally be firmly anchored in the groove. On the other hand, the through-openings 34 form the groove bottom of an axially outer groove between a collar 22 and a collar 24.As a result of this arrangement of sealing region-in the form of a sealing adhesive connection 52 (see FIG. 2, not shown in FIG. 3 for the sake of better clarity)-and supporting structure 40, the axially upper surface of the sealing adhesive connection 52 and the axially lower surface 42 of the supporting structure 40 can be located axially on different planes, which is not possible with a continuously foamed polyurethane end plate. Because the surfaces of the foamed volumes of sealing region and supporting structure 40 can be arranged on different planes, in particular the axially lower surface of the supporting structure can be axially further away from the air outlet than the axially upper surface of the adhesive region or the end face of the filter body.The support knobs 44 of the closed end disk 20, which are arranged so as to extend radially outwards in a circular manner about the longitudinal axis L, can, when the filter element 10 is installed in the housing 108 (FIG. 1 ), be supported axially on the housing 108 so as to rest against an inner cover contour of the cover 110.On the opposite end face 60 of the filter body 12 there is arranged an open annular end plate 70 which, in the installed state, effects a radial sealing and is provided with supporting knobs 72 which project axially from the filter body 12. The open end plate 70 is advantageously formed from polyurethane, which is foamed onto the end face 60.The filter body 12 can consist, for example, of a filter bellows folded in a zigzag shape (pleated) and can be embodied closed in an annular manner. The folding can be produced, for example, by blade folding, for longer filter bodies 12, or rotational folding. The filter bellows can consist, for example, of paper, cellulose or a mixed fiber of plastic and cellulose and can be designed with a smooth surface, rolled and / or surface designed in various embossing shapes for stiffening and / or creating cavities for dust deposition. The filter bellows may have a coating and / or impregnation to reject moisture. Alternatively, it can also be coated with nanofibers. The filter body 12 can furthermore be structurally reinforced, for example with a continuous strip of hot-melt adhesive, a wound adhesive strip, a so-called thread winding in the form of a thread, band or the like impregnated with hot-melt adhesive.The bulge 30 of the closed end plate 20 creates a free space within the filter element 10, which makes it possible, if necessary, to provide a central tube within the filter element 10, which tube protrudes axially beyond the filter body 12. Optionally, additionally or alternatively, a secondary filter element may also be provided, if necessary, which protrudes axially beyond the filter element 10. The central tube and secondary filter element can thereby be arranged independently of the sealing structure of the filter element 10.FIG. 4 shows a sectional view through a filter system 100 with a primary filter element 10 and secondary filter element 80 and with a central tube 90 according to an embodiment of the invention. FIG. 5 shows a sectional illustration of a detail of the filter system 100 from FIG. 4.The filter system 100 has a radially arranged inlet connection piece 102 and a central outlet connection piece 104 in a housing 108. The housing 108 is closed on one end side by a cover 110. In the case of an air filter system, dust-laden air flows into the inlet connection piece 102, which is arranged, for example, radially with respect to the filter element 10 installed on the inside. The cleaned air can be discharged from the housing 108 via the central outlet connection 104. The inlet connection piece 104 can be welded with its collar 106 to the previously perforated housing 108 in any angular position. The filter system 100 can be used as an air filter, for example in construction machines, agricultural machines, compressors and other devices with an internal combustion engine.Disposed within the housing 108 is a filter element 10 concentrically surrounding a center tube 90 and a secondary filter element 80. The optional central tube 90 is arranged fixed to the housing and is snapped onto the housing 108 at the outlet-side housing end. The filter body 12 can be conically shaped and have a larger outer diameter on the closed end plate than on its opposite end face 60. The end plate 20 has an insertion bevel on the inside in the region in which the central tube 90 engages, which insertion bevel centers the filter element 10 during assembly on the central tube 90.The embodiment of the filter element 10 with the end plate 20 and the supporting structure 40 is described in FIGS. 2 and 3, to which reference is made. The central tube 90 and the secondary filter element 80 project into the bulge 30 of the closed end plate 20 and thus project axially beyond the filter element 10.The secondary filter element 80 essentially consists of a support tube 82 as a supporting structure and a relatively permeable filter medium 84, for example a fleece, arranged thereon. The secondary filter element 80 can remain in the housing 108 during the replacement of the filter element 10 for protecting the further air guidance, for example of an internal combustion engine, against entering dust particles and other objects. The open end of the secondary filter element 80 is inserted into a housing seat on the outlet-side part of the housing 108. The closed end 86 of the secondary filter element 80 abuts in the bulge 30 of the closed end plate 20 of the filter element 10, whereby when the housing cover 110 is closed, a force can be conducted via the support knobs 44 of the end plate 20 into the closed end of the secondary filter element 80 and the secondary filter element 80 is pressed firmly into its housing seat on the outlet connector 104. The closed end 86 is adjoined by a handle 88 which facilitates removal of the secondary filter element 80.In this way, the filter element 10, in addition to the central tube 90, is braced axially against the cover 110 and thus against the housing 108 via the closed end plate 20 and is thereby fixedly mounted on the end face 50, the cover-side end of the filter element 10.

Claims

Filter element (10) comprising a closed filter body (12) elongated along a longitudinal axis (L) and a closed end plate (20) firmly connected thereto, to which the filter body (12) is tightly connected with its end face (50), wherein the end plate (20) has a fixing position (32) for an axially outwardly protruding support structure (40), wherein the fixing position (32) is arranged in a bulge (30) of the end plate (20) and the fixing position (32) is arranged in front of the end face (50) of the filter body (12) to the outside with respect to a radial position inside an outer skin of the filter body (12) and axially of the end face (50) of the filter body (12) and the bulge (30) extends a space defined by an inner side of the filter body (12), wherein the bulge (30) has through openings (34) in the axial direction.Filter element according to claim 1, wherein the through-openings (34) are traversed by the support structure (40).Filter element according to one of the preceding claims, wherein the supporting structure (40) is formed from an elastomer, in particular polyurethane.Filter element according to one of Claims 1 to 3, wherein the filter body (12) is foamed onto the end plate (20) on its end face (50) with an elastomer, in particular polyurethane.Filter element according to one of Claims 1 to 3, wherein the filter body (12) is adhesively bonded to the end plate (20) on its end face (50) with an adhesive.Filter element according to one of Claims 1 to 3, wherein the filter body (12) is welded to the end plate (20) on its end face (50).Filter element according to one of the preceding claims, wherein the filter body (12) is formed in a star-folded manner.Filter element according to one of the preceding claims, wherein the filter body (12) is conically shaped and has a larger outer diameter on the closed end plate (20) than on its opposite end side (60).Filter element according to one of the preceding claims, wherein the bulge (30) is formed hollow cylindrically.Filter element according to one of the preceding claims, wherein the bulge (30) is designed to receive a secondary filter element (80).Filter element according to one of the preceding claims, wherein the bulge (30) is arranged within a clear width of the filter body (12).Filter system (100) comprising - a housing (108) having a longitudinal axis (L), - a cover (110) which closes the housing (108) on an end face, - an inlet connection piece (102) arranged on the housing (108) for supplying a medium to be filtered and an outlet connection piece (104) arranged on the housing (108) for discharging the filtered medium, and - an exchangeable filter element (10) according to one of the preceding claims.Filter system (100) according to claim 12, wherein a middle tube (90) fixed to the housing is provided.Use of a filter system (100) according to one of Claims 12 to 13 as an air filter, in particular as an air filter of an internal combustion engine.

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