Secondary filter element and filter arrangement

A secondary filter element for a filter arrangement is provided with a filter medium and a circumferentially extending sealing device that seals the secondary filter element in respect to a filter receptacle of the filter arrangement. The circumferentially extending sealing device has an oval geometry with a long side and a short side. The circumferentially extending sealing device has an outer surface projecting, in a radial direction of the secondary filter element, farther past the filter medium when viewed along the short side compared to when viewed along the long side. A filter arrangement has a filter receptacle. A main filter element is received in the filter receptacle, and a secondary filter element is received in the main filter element. The circumferentially extending sealing device of the secondary filter element projects in a radial direction of the secondary filter element outwardly past an interior of the main filter element.

BACKGROUND OF THE INVENTION

The present invention concerns a secondary filter element for a filter arrangement and a filter arrangement with such a secondary filter element.

Known air filter arrangements for vehicles, in particular in the field of agricultural commercial vehicles and construction vehicles, can comprise a main filter element received in a filter receptacle and a secondary filter element received in the main filter element. Such a secondary filter element serves in particular as a safety means in the cases in which an operator, while the internal combustion engine is running, opens the filter receptacle and removes the main filter element, for example, for dust removal or exchange. The secondary filter element prevents that the internal combustion engine with the main filter element removed sucks in particles, for example, dust or sand.

EP 3 085 428 A1 discloses a filter arrangement with a main filter element and a secondary filter element received in the main filter element. The main filter element comprises in its length direction an oval cross section and comprises a circumferentially extending sealing device for sealing the main filter element in respect to the filter receptacle. The secondary filter element comprises also an oval cross section with a circumferentially extending sealing device.

SUMMARY OF THE INVENTION

In view of this background, the present invention has the object to provide an improved filter element.

Accordingly, a filter element, in particular a secondary filter element, for a filter arrangement is proposed. The filter element comprises a filter medium and a circumferentially extending sealing device for sealing the filter element with respect to a filter receptacle for the filter element, wherein the sealing device comprises an oval geometry with a long side and a short side, and wherein an outer surface of the sealing device projects radially farther past the filter medium when viewed along the short side compared to when viewed along the long side.

The filter element is preferably an air filter element for filtering intake air for an internal combustion engine. Preferably, the filter element is used in motor vehicles, trucks, construction vehicles, watercraft, rail vehicles, agricultural machines or vehicles, or aircraft. The filter element is preferably an auxiliary filter element, auxiliary element, secondary filter element or secondary element of the filter arrangement or can be referred to as such. The filter arrangement furthermore comprises preferably a main filter element, main element, primary filter element or primary element in which the secondary filter element is received. The main filter element can also be referred to as first filter element of the filter arrangement and the secondary filter element can also be referred to as second filter element of the filter arrangement.

The filter element comprises preferably a filter medium in the form of a filter paper, a woven filter material, a laid filter material, or a filter nonwoven. In particular, the filter medium can be produced by a spunbond or melt-blown method or can comprise such a fiber layer which is applied onto a nonwoven or cellulose carrier. Moreover, the filter medium can be felted or needled. The filter medium can comprise natural fibers, such as cellulose or cotton, or synthetic fibers, for example, of polyester, polyvinyl sulfate or polytetrafluoroethylene. The filter medium is preferably not folded, but flat.

The sealing device is preferably resiliently deformable. The sealing device extends preferably completely about the filter element and comprises, in addition to the outer surface, an inner surface which is facing away from the outer surface. By means of the inner surface, the filter medium can be sealed radially with respect to a seal contact surface of an engagement region of the filter receptacle. “Radial” is to be understood herein as a direction which is oriented away from a center axis of the filter element. This means that the filter element comprises a radial direction that is oriented perpendicularly to the center axis and is oriented away from the latter. The center axis extends in this context in particular parallel to a length direction of the filter element. Preferably, the center axis extends through a point of intersection of the long side and the short side.

The sealing device comprises in particular, viewed in length direction, an oval geometry or an oval cross section. “Oval” can be understood herein as a geometry or shape with non-concave, flat outer contour. In particular, this geometry can be formed continuously of convex and straight sections, preferably exclusively of convex sections. In particular, “oval” can be understood, for example, also as a rectangular cross section with rounded corners, an elliptical cross section or a cross section which is formed of a plurality of circular arcs. Preferably, an oval outer contour or an oval cross section is used which comprises a center point and two symmetry axis that intersect thereat. The symmetry axes comprise in particular the long side and the short side. The symmetry axes can also be referred to as major axis and minor axis. In particular, the aforementioned long side corresponds to the main axis and the short side corresponds to the minor axis. The long side is arranged perpendicularly to the short side and in particular cuts it in half. In reverse, the short side also cuts in half the long side. That the outer surface of the sealing device projects radially farther past the filter medium when viewed along the short side compared to when viewed along the long side, is to be understood particularly such that the outer surface projects farther past the filter medium when viewed in a direction oriented parallel to the short side compared to when viewed in a direction oriented parallel to the long side.

Since the outer surface of the sealing device projects past the filter medium, an outflow cross section of the filter element, in comparison to a filter element without a sealing device designed in this way, can be enlarged because the sealing device does not constrict it. Moreover, a radius of curvature of the sealing device can be optimized whereby an improved, in particular radial, sealing action with respect to the filter receptacle can be achieved.

In embodiments, the filter element comprises moreover a central tube for support of the filter medium, wherein the sealing device is connected to the central tube and wherein a first cross section surface of the filter element, delimited by an inner surface of the sealing device, is larger than a second cross section surface of the filter element, delimited by an inner contour of the central tube. The second cross section surface can be referred to also as outflow surface or outflow cross section of the filter element. Since the first cross section surface is larger than the second cross section surface, the sealing device does not constrict the outflow cross section of the filter element.

In embodiments, the inner surface of the sealing device projects radially farther past the inner contour of the central tube when viewed along the short side compared to when viewed along the long side. In particular, the inner surface, viewed along the short side as well as viewed along the long side, projects radially past the inner contour of the central tube, wherein the inner surface however projects farther viewed along the short side. In this way, a constriction of the outflow cross section of the filter element is avoided.

In embodiments, the central tube comprises a support section for supporting the filter medium, a sealing section with which the sealing device is connected, and a connecting section arranged between the support section and the sealing section and, beginning at the sealing section, tapering conically in the direction toward the support section. The support section is preferably grid-shaped and not fluid-permeable. For example, the filter medium can be wound onto the support section. The sealing section comprises preferably an oval geometry and extends circumferentially completely about the filter element. The sealing device can be, for example, cast onto the sealing section. The sealing device can be manufactured, for example, from polyurethane foam. The connecting section connects the support section with the sealing section as one piece, in particular monolithically. The central tube is preferably an injection molded plastic component.

In embodiments, the sealing device comprises two first curved sections that are positioned opposite each other and two second curved sections that are positioned opposite each other, wherein a radius of curvature of the second curved sections is larger than a radius of curvature of the first curved sections. The radius of curvature of the second curved sections can tend toward infinity. This means that the radius of curvature of the second curved sections can also be embodied at least approximately straight. In particular, the curved sections are connected to each other as one piece, in particular monolithically. Preferably, the first curved sections are positioned mirror-symmetrically with respect to the short side, and the second curved sections are positioned preferably mirror-symmetrically with respect to the long side.

In a particularly preferred embodiment, the sealing device comprises a substantially stadium-like geometry. It has been found to be advantageous that the sealing device comprises in particular no straight sections, but only curved sections. Since the sealing device is substantially comprised exclusively of curved sections, a constant contact pressure against the engagement region of the filter receptacle can be achieved about its entire circumference. The sealing device is preferably configured to seal the filter element with respect to the filter receptacle radially inwardly. Stronger curvatures or smaller radii at the sealing device are more advantageous in case of radial sealing action in inward or outward direction than weaker curvatures or larger radii because with increasing curvature the risk decreases that the sealing device upon vibration load loses contact with respect to the seal contact surface at the filter receptacle. The sealing device can alternatively or additionally also be configured to axially seal the filter element with respect to the filter receptacle. “Axial” is to be understood herein as a direction which is oriented axially toward a fluid outlet of the filter receptacle.

In embodiments, the first curved sections are correlated with the long side wherein the second curved sections are correlated with the short side and wherein the second curved sections project radially farther past the filter medium viewed along the short side than the first curved sections viewed along the long side. That the first curved sections are correlated with the long side is to be understood in particular such that the curvature center points of the first curved sections are arranged on the long side. Correspondingly, curvature center points of the second curved sections are positioned in particular on the short side.

Moreover, a filter arrangement is proposed comprising a filter receptacle, a filter element received in the filter receptacle, in particular a main filter element that comprises a filter medium and a circumferentially extending sealing device for sealing the filter element with respect to the filter receptacle, and an additional filter element received in the filter element, in particular a secondary filter element that comprises a sealing device for sealing the additional filter element with respect to the filter receptacle, wherein the sealing device of the additional filter element projects radially past the interior of the filter element that is delimited by the inner wall surface of the filter medium or a central tube of the filter element. This means that the sealing device projects radially at least past the inner side of the open end disk (i.e., the opening delimited by the open end disk) and preferably at least past a central tube of the filter element, if it is present, and past the inner wall surface of the filter medium of the filter element when no central tube is present. Of course, the sealing device can also project additionally radially past the inner wall surface of the filter medium when the filter element comprises a central tube. The main filter element can also be referred to as first filter element and the secondary filter element can be referred to also as second filter element. In particular, the secondary filter element is received in the main filter element. In the following, the main filter element is referred to as filter element and the secondary filter element as additional filter element. Since the sealing device of the additional filter element projects radially past the filter medium of the filter element, an outflow cross section of the filter element is advantageously not constricted by the sealing device of the additional filter element. That the sealing device of the additional filter element projects radially past the interior of the filter element, is to be understood in particular such that the sealing device projects past an inner wall surface of the filter medium and/or a central tube of the filter element (if present). The sealing device preferably does not project past an outer wall surface of the filter medium of the filter element.

In embodiments, the sealing device of the additional filter element comprises an oval geometry with a long side and a short side, wherein an outer surface of the sealing device of the additional filter element projects radially farther past the filter element of the main filter element when viewed along the short side compared to when viewed along the long side. This means in particular that the sealing device of the additional filter element overlaps at least partially the sealing device of the main filter element.

In embodiments, the sealing device of the additional filter element is arranged completely outside of the filter medium of the main filter element. In particular, viewed in a length direction of the filter receptacle, the sealing device of the additional filter element is positioned adjacent to the filter medium of the filter element.

In embodiments, the sealing device of the filter element and the sealing device of the additional filter element seal radially with respect to the filter receptacle, wherein the sealing device of the additional filter element at least in sections is arranged inside of the sealing device of the filter element. In particular, the sealing device of the filter element completely surrounds circumferentially the sealing device of the additional filter element. This means that, viewed in axial direction, the sealing device of the additional filter element at least in sections is arranged at the same level as the sealing device of the filter element.

In embodiments, the sealing device of the main filter element and the sealing device of the secondary filter element extend parallel to each other. Preferably, in this context the sealing surfaces, i.e., in an embodiment as a radial seal regularly the inner surfaces, are arranged to extend parallel to each other. Parallel extending is to be understood herein such that, viewed along a center axis, the annular extensions of the sealing devices or sealing surfaces are circumferentially extending parallel to each other about the center axis.

In the Figures, same or functionally the same elements, if nothing to the contrary is indicated, have been provided with the same reference characters.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG.1shows a schematic perspective view of an embodiment of a filter arrangement1.FIG.2shows a front view of the filter arrangement1.FIGS.3and4show respectively a side view of the filter arrangement1.FIGS.5and6show respectively section views of the filter arrangement1according to the section line V-V and VI-VI, respectively, ofFIG.4, andFIG.7shows a further section view of the filter arrangement1according to the section line VII-VII ofFIG.4.FIG.8shows the detail view VIII according toFIG.7, andFIG.9shows a schematic partial section view of the filter arrangement1. In the following, reference is being had toFIGS.1to9simultaneously.

The filter arrangement1can also be referred to as filter system. The filter arrangement1comprises a filter receptacle2and a filter element3arranged in the filter receptacle2. The filter receptacle2can also be referred to as housing or filter housing. The filter element3is shown in a schematic perspective view inFIG.10. The filter arrangement1is used preferably as an intake air filter for an internal combustion engines, for example, in motor vehicles, trucks, construction vehicles, watercraft, rail vehicles, agricultural machines or vehicles, or aircraft. The filter arrangement1can also be used in immobile applications, for example, in building technology. The filter element3is in particular suited to filter combustion air of an internal combustion engine. Preferably, the filter element3is an air filter element.

The filter element3illustrated inFIGS.10to12is a main filter element, main element, primary filter element or primary element, or can be referred to as such. Moreover, the filter element3can also be referred to as first filter element of the filter arrangement1. The filter element3comprises a filter medium4that surrounds a central tube5and preferably contacts it such that the central tube5can provide a support function for the filter medium4upon flow therethrough. The filter medium4can also be referred to as filter body. The central tube5can also be referred to as support tube. The central tube5is preferably grid-shaped and thus fluid-permeable.

For example, the filter medium4can be wound as a coil of a filter material onto the central tube5or can contact it in an annular closed shape, for example, in the form of a star-shaped folded bellows. The filter medium4is preferably folded. For stabilization, the folded filter medium4can be wrapped with a fixation coil6, i.e., a strip or thread that has been impregnated with a hot melt or another adhesive, or can be fixed by means of adhesive beads extending about the circumference in a circular or spiral shape. The fixation coil6can also be referred to as thread coil.

The filter medium4is, for example, a filter paper, a woven filter material, a laid filter material or filter nonwoven. In particular, the filter medium4can be produced by spunbond or melt-blown method or can comprise such a fiber layer applied onto a nonwoven or cellulose carrier. Moreover, the filter medium4can be felted or needled. The filter medium4can comprise natural fibers, such as cellulose or cotton, or synthetic fibers, for example, of polyester, polyvinyl sulfate or polytetrafluoroethylene. Fibers of the filter medium4can be oriented during manufacture in a machining direction, at a slant and/or transversely thereto or randomly.

The filter element3comprises a first, in particular open, end disk7and a second, in particular closed, end disk8. The end disks7,8are preferably manufactured from plastic material. For example, the end disks7,8can be embodied as cost-efficient injection molded plastic components. The end disks7,8can also be manufactured, for example, from polyurethane material cast in casting molds, preferably foamed. The end disks7,8can be cast onto the filter medium4. The filter medium4is arranged between the end disks7,8. The filter medium4can be fused, glued or welded to the end disks7,8.

At a front side9of the first end disk7which is facing away from the filter medium4, a sealing device10for sealing the filter element3with respect to the filter receptacle2is provided. The sealing device10is configured to seal the filter element3, in particular radially, with respect to the filter receptacle2.

The second end disk8is, for example, plate-shaped and preferably fluid-impermeable. In the first end disk7, a receiving opening11is provided through which fluid L that has been filtered by means of the filter element3can exit. The fluid L is preferably air. Moreover, the filter element3preferably comprises an inflow protection12which prevents a direct flow of particle-laden fluid L against the filter medium4. The inflow protection12can be a film or a closed mesh net or grid. The inflow protection12can be fluid impermeable or fluid permeable. The inflow protection12can be glued, welded or fused to the filter medium4. The inflow protection12is arranged neighboring the first end disk7. In particular, the inflow protection12adjoins the first end disk7. The inflow protection12can be connected in particular flow-tightly to the first end disk7.

Fluid L to be purified passes from the raw side RO of the filter element3through the filter medium4to a clean side RL of the filter element3surrounded by the central tube5. The fluid L flows out of the filter element3through the receiving opening11as filtered fluid L. The filter element3and in particular the filter medium4have a width b and a height h (FIG.6). The width b is greater than the height h. Preferably the width b amounts to 2 times to 3 times the height h, further preferred the width b amounts to 1.5 times to 3 times the height h.

The filter element3comprises, viewed in a length direction LR3thereof, preferably an oval cross section. The cross section, beginning at the first end disk7, can decrease in the direction toward the second end disk8so that the filter element3tapers conically. Preferably, however, the filter element3, as illustrated inFIGS.10and11, has an oval cross section. This means that the filter element3is cylinder-shaped with an oval base surface.

“Oval” can be understood presently as a shape with non-concave flat outer contour, which means formed continuously of convex and straight sections, preferably exclusively of convex sections, for example, a rectangular cross section with rounded corners, an elliptical cross section or a cross section that is formed of a plurality of circular arcs. Preferably, an oval outer contour or an oval cross section is used which comprises a center point and two symmetry axes intersecting each other thereat.

The second end disk8can have, for example, clamping elements13of which inFIG.11only one is provided with a reference character. The clamping elements13can be elastically deformable projections projecting in the length direction LR3away from the second end disk8by means of which the filter element3can be elastically clamped in the filter receptacle2. The number of clamping elements13is arbitrary. By means of the elastically deformable clamping elements13, the filter element can be optimally positioned in the filter receptacle2with regard to the length direction LR3. The clamping elements13serve moreover for vibration damping and/or tolerance compensation. The second end disk8is preferably formed monolithically together with the clamping elements13. For example, the second end disk8together with the clamping elements13can be formed from a polyurethane foam.

At the first end disk7and in particular at the front side9of the first end disk7which is facing away from the filter medium4, the elastically deformable sealing device10for sealing the filter element3with respect to the filter receptacle2is provided. The sealing device10is resiliently deformable. Preferably, the first end disk7and the sealing device10are embodied monolithically. For example, the first end disk7and the sealing device10can be manufactured from a polyurethane foam. The sealing device10surrounds the first end disk7completely. The sealing device10is located, in particular in a projection in the length direction LR3, completely inside a cross section of the filter medium4. As shown also inFIG.11, the sealing device10comprises an outer circumferential surface14that is facing away from the central tube5as well as an inner surface15that is facing away from the outer surface14and also surrounds completely the filter element3. The sealing device10comprises an oval geometry or an oval cross section.

The sealing device comprises, as shown inFIG.12, two first convex curved sections16,17that are arranged opposite each other. The first curved sections16,17comprises each a first radius of curvature R16, R17. The first radii of curvature R16, R17are preferably of the same size. The first radii of curvature R16, R17comprise first curvature center points M16, M17. The first curvature center points M16, M17are positioned on a common long side18of the sealing device10. The long side18can also be referred to as long side of the oval geometry of the sealing device10. The long side18is a straight line. The long side18can furthermore be referred to as major axis of the sealing device10or as major axis of the oval geometry of the sealing device10. Between the curvature center points M16, M17, the long side18has a length a18.

The sealing device10comprises moreover two second convex curved sections19,20that are arranged opposite each other. The first curved sections16,17and the second curved sections19,20are connected to each other monolithically. The second curved sections19,20comprise second radii of curvature R19, R20with second curvature center points M19, M20. The second radii of curvature R19, R20are preferably of the same size. The second radii of curvature R19, R20are larger than the first radii of curvature R16, R17. The second curvature center points M19, M20of the second radii of curvature R19, R20are positioned on a common short side21of the sealing device10. The short side21can also be referred to as short side of the oval geometry of the sealing device10. The short side21is a straight line. The short side21can moreover be referred to as minor axis of the sealing device10or as minor axis of the oval geometry of the sealing device10. Between the curvature center points M19, M20, the short side21has a length a21. The length a18is larger than the length a21.

The short side21is arranged perpendicularly to the long side18. Preferably, the short side21divides the long side18centrally, and vice versa. Preferably, the short side21and the long side18intersect each other at a point of intersection through which, viewed in the length direction LR3, a center axis MA3of the filter element3is extending which is preferably positioned, when the filter element3is installed in the filter receptacle2, in overlap with a center axis MA2(FIGS.3and4) of the filter receptacle2. In this context, the center axis MA3is parallel to the length direction LR3. The first curved sections16,17are positioned mirror-symmetrically in relation to the short side21, and the second curvature sections19,20mirror-symmetrically positioned in relation to the long side18. The sealing device10comprises moreover an outer contour22at the outer surface14. The outer contour22preferably does not extend parallel to an outer contour23of the first end disk7.

In the filter receptacle2, surrounded by the filter element3, an additional filter element24as shown inFIGS.13to17can be received. The filter element24is an auxiliary filter element, auxiliary element, secondary filter element or secondary element or can be referred to as such. Moreover, the filter element24can also be referred to as second filter element of the filter arrangement1. Such secondary filter elements serve in particular as a safety means for the cases that an operator opens the filter receptacle2while the engine is running and removes the filter element3, for example, for dust removal or exchange.

Preferably, the filter element24is received in the receiving opening11of the filter element3. The filter element24comprises a filter medium25as well as a central tube26that supports the filter medium25. The central tube26is preferably grid-shaped and thus fluid-permeable. The filter medium25can be wound as a coil onto the central tube26or can contact it in an annular closed shape, for example, in the form of a star-shaped folded bellows. The filter medium25is however preferably flat and thus not folded, as shown inFIGS.16and17.

The filter medium25is, for example, a filter paper, a woven filter material, a laid filter material or a filter nonwoven. In particular, the filter medium25can be produced by a spunbond or melt-blown method or can comprise such a fiber layer applied onto a nonwoven or cellulose carrier. Moreover, the filter medium25can be felted or needled. The filter medium25can comprise natural fibers, such as cellulose or cotton, or synthetic fibers, for example, of polyester, polyvinyl sulfate, or polytetrafluoroethylene. Fibers of the filter medium25can be oriented during manufacture in a machining direction and/or transverse thereto or randomly.

The central tube25comprises a grid-shaped support section27which is fluid-permeable and supports the filter medium25. At the end face, the support section27is closed by a fluid-tight bottom section28A. In this context, the bottom section28A is preferably formed monolithically with the support section27. A support element28B can be integrally formed at the bottom section28A. The support element28B in the mounted state of the filter element24can be supported on the second end disk8of the filter element3.

The support section27is oval in cross section. In addition to the support section27and the bottom section28A, the central tube26comprises a sealing section29(FIG.17) which in cross section is also oval. Circumferentially about the filter element24, the sealing section29projects radially past the support section27. “Radial” is to be understood herein as a direction, in particular a radial direction R, perpendicular to and pointing away from a center axis MA24of the filter element24. The center axis MA24extends in this context parallel to a length direction LR24of the filter element24.

Between the sealing section29and the support section27, a connecting section30is provided. The connecting section30connects the sealing section29monolithically to the support section27. In this context, the connecting section30is oval in cross section and tapers conically, beginning at the sealing section29, in the direction toward the support section27. Preferably, the central tube26is a one piece, in particular monolithic, injection molded plastic component.

The filter element24comprises moreover a sealing device31. The sealing device31is elastically deformable. For example, the sealing device to31is manufactured from a polyurethane material. The sealing device31is integrally formed at the sealing section29of the central tube26or is cast onto it. The sealing device31comprises an outer surface32A extending circumferentially about the center axis MA24, a circumferentially extending inner surface32B facing away from the outer surface32A, as well as a circumferentially extending end face32C. The sealing device31comprises in this context an oval geometry or an oval cross section.

As shown inFIG.13, the sealing device31comprises two first convex curved sections33,34that are positioned opposite each other as well as two second convex curved sections35,36that are positioned opposite each other. The first curved sections33,34are monolithically embodied with the second curved sections35,36wherein the curved sections33to36are arranged such that between the two first curved sections33,34the two second curved sections35,36and between the two second curved sections35,36the two first curved sections33,34are arranged.

The first curved sections33,34each comprise a first radius of curvature R33, R34. The first radii of curvature R33, R34are preferably of the same size. The first radii of curvature R33, R34comprise first curvature center points M33, M34. The first curvature center points M33, M34are positioned on a common long side37. The long side37can also be referred to as long side of the oval geometry of the sealing device31. The long side37is a straight line. The long side37can moreover be referred to as major axis of the sealing device31or as major axis of the oval geometry of the sealing device31. Between the first curvature center points M33, M34, the long side37has a length a37.

The second curved sections35,36comprise second radii of curvature R35, R36. The second radii of curvature R35, R36are of the same size. Second curvature center points M35, M36of the second radii of curvature R35, R36are positioned on a common short side38. The short side38can also be referred to as short side of the oval geometry of the sealing device31. The short side38is a straight line. The short side38can moreover be referred to as minor axis of the sealing device31or as minor axis of the oval geometry of the sealing device31. Between the second curvature center points M35, M36, the short side38has a length a38. The length a37is larger than the length a38.

Preferably, the long side37divides the short side38centrally, and vice versa. Preferably, the short side38and the long side37intersect at a point of intersection through which, viewed in the length direction LR24, the center axis MA24is extending which is preferably positioned, when the filter element24is installed in the filter receptacle2, in overlap with the center axis MA2of the filter receptacle2as well as the center axis MA3of the filter element3. The first curved sections33,34are positioned mirror-symmetrically with respect to the short side38, and the second curved sections35,36are mirror-symmetrically positioned with respect to the long side37.

As shown inFIG.14, the inner surface32B of the sealing device31delimits a first cross section surface A1of the filter element24. As shown inFIG.15, an inner contour39of the central tube26delimits a second cross section surface A2of the filter element24. In this context, the first cross section surface A1is larger than the second cross section surface A2. The second cross section surface A2can also be referred to as outflow cross section of the filter element24. Since the first cross section surface A1is larger than the second cross section surface A2, the sealing device31does not delimit the second cross section surface A2and thus also does not delimit the outflow cross section of the filter element24.

The sealing device31projects, viewed in the radial direction R, circumferentially past the filter medium25. In this way, in comparison to a filter element without such a projecting sealing device31, the radii of curvature R33to R36can be selected larger whereby an improved sealing action with respect to the filter receptacle2results. Viewed along the short side38, the inner surface32B of the sealing device31projects radially farther past the inner contour39of the central tube26than viewed along the long side37. Accordingly, also the outer surface32A of the sealing device31, viewed along the short side38, projects radially farther past the filter medium25than viewed along the long side37.

Returning now to the filter arrangement1according toFIGS.1to9. The filter receptacle2comprises a receiving section40. The receiving section40can be embodied as one piece or as a multi-part configuration. The receiving section40is preferably manufactured from a plastic material. Alternatively, the receiving section40can be manufactured from sheet metal, in particular sheet steel. For example, the receiving section40can be embodied as a cost-efficient injection molded plastic component.FIGS.1to3and9show a different possibility of configuring the receiving section40in comparison toFIGS.4to8.

Moreover, the filter receptacle comprises a service cover41removable from the receiving section40. By means of the service cover41, the filter elements3,24can be removed from the receiving section40. The service cover41can be connected by means of quick connect devices42to the receiving section40. Between the service cover41and the receiving section40, a sealing device can be provided.FIGS.2and3show the filter arrangement1in two different installation situations, namely in a horizontal one and an upright one.

The filter receptacle2or the receiving section40comprises a fluid inlet43for inflow of the fluid L to be filtered into the filter receptacle2and an in particular central fluid outlet44for outflow from the filter receptacle2of the fluid L that has been filtered by means of the filter element3. The fluid inlet43and the fluid outlet44are preferably embodied tubular. The fluid inlet43, as shown inFIGS.1and3, can comprise an oval cross section. By means of the oval cross section, whose wider expansion is preferably oriented in the direction of a length direction LR2of the filter receptacle2, a reduced initial pressure loss can be achieved in comparison to a circular cross section.

The fluid L to be filtered enters the fluid inlet43in a flow direction E. The fluid outlet44comprises preferably a circular cross section. The fluid L exits from the fluid outlet44in an outflow direction A preferably parallel to the length direction LR3of the filter element3or of the length direction LR2of the filter receptacle2. The inflow direction E is oriented perpendicularly to the outflow direction A.

A particle discharge opening45can be provided at the service cover41. The particle discharge opening45is preferably tubular. By means of the particle discharge opening45, particles46(FIG.9) that have been separated from the fluid L can be discharged from the filter receptacle2. The particle discharge opening45can comprise a valve47, in particular a lip valve or a so-called duckbill valve. The particles46can comprise, for example, dust, soil, sand, plant parts or the like.

In the filter receptacle2and in particular in the receiving section40, a first engagement region48(FIG.8) is provided which is engaged by the sealing device10of the filter element3. This first engagement region48comprises preferably a seal contact surface49that can be contacted seal-tightly by the sealing device10with the inner surface15. In the present embodiment, preferred as shown, an oval cylinder-shaped, radially outwardly oriented seal contact surface49is provided which follows the course of the inner surface15of the sealing device10.

Furthermore, at the receiving section40a second engagement region50can be provided which is engaged by the sealing device31of the filter element24. This second engagement region50comprises preferably also a seal contact surface51that can be contacted seal-tightly by the sealing device31with its inner surface32B. In the present embodiment, preferred as shown, an oval cylinder-shaped, radially outwardly oriented seal contact surface51is provided. The engagement regions48,50surround the fluid outlet44completely. The engagement regions48,50have an oval geometry. The second engagement region50is positioned inside the first engagement region48.

As shown inFIG.5, the fluid inlet43is arranged such that the inflow direction E of the fluid L is oriented in the direction toward an outer wall surface52and perpendicularly to the length direction LR3of the filter element3arranged in the receiving section40. The outer wall surface52forms an envelope of the filter element4of the filter element3. A cylindrical, in particular oval cylindrical, geometry of the filter element3is formed by the end disks7,8and the outer wall surface52. An inner wall surface of the filter medium4is defined by the central tube5. The fluid L to be filtered flows about the filter element3received in the receiving section40such that particles46contained in the fluid L to be filtered are separated by means of the centrifugal force at a wall53of the filter receptacle2or of the receiving section40. The receiving section40acts as a centrifugal separator. In particular, the inflow direction E is oriented such that the fluid L to be filtered flows substantially tangentially about the filter element3.

The receiving section40comprises in cross section preferably a width direction br and a height direction hr. A width/height ratio b/h amounts preferably to at least 4:3, further preferred at least 3:2, in particular at least 2:1, and/or at most 6:1, preferably at most 4:1, particularly preferred at most 3:1 or 2:1. For the purposes of an optimized preseparation, ratios of smaller than 3:1 and preferably smaller than 2:1 or even smaller than 1.5:1 are advantageous. Preferably, the fluid inlet43is arranged such that the inflow direction E is oriented perpendicularly to the width direction br, i.e., preferably perpendicularly to the direction of the wider expansion of the filter element3.

Since the fluid inlet43is preferably oriented such that the inflowing fluid L impinges on a comparatively more strongly curved curvature54of the wall53of the receiving section40, the fluid L to be filtered is strongly accelerated and flows subsequently about the filter element3tangentially and in particular in a screw shape, spirally or helically. In this way, a good separation of the particles46from the fluid L is achieved.

The fluid inlet43can be shielded by means of a wall55from the fluid L flowing about the filter element3. The wall55supports the formation of a screw-shaped flow about the filter element3. The separated particles46are removed by means of the particle discharge opening45from the receiving section40.

The receiving section40extends in the length direction LR3of the filter element3parallel to the outer wall surface52of the filter element3so that, as shown inFIG.6, perpendicular to the length direction LR3, a uniform distance a between filter element3and the wall53is provided circumferentially about the filter element3.

FIG.9shows a partial section view of the filter arrangement1. The fluid L to be filtered flows through the fluid inlet43into the receiving section40. Since the inflow direction E of the fluid L to be filtered is oriented in the direction toward the outer wall surface52of the filter element3and in particular also perpendicularly to the length direction LR3, the fluid L to be filtered flows, as shown inFIG.9by means of arrow56, in a screw shape about the filter element3and flows through the filter medium4of the filter element3to then flow out from the fluid outlet44of the filter receptacle2in the outflow direction A as filtered fluid L.

Upon flowing about the filter element3, the particles46are separated from the fluid L to be filtered at the wall53of the receiving section40by means of the centrifugal force and can be removed through the particle discharge opening45from the receiving section40. The particles46can be discharged, for example, by means of the valve47, from the particle discharge opening45. The valve47can be controlled, for example, by a load change of an internal combustion engine connected to the filter arrangement1. In comparison to a circular cross section, a beneficial particle separation with simultaneous suitability of the filter arrangement1for installation spaces that do not have a circular or square cross section is realized due to the oval cross section geometry of the receiving section40.

As furthermore shown inFIGS.6,7, and9, the service cover41comprises a tubular, in particular oval tubular, inflow protection57in which the filter element3is at least partially received, preferably such that between the filter element3and the inflow protection57a flow gap of a few millimeters is provided. The inflow protection57can be embodied monolithically with the service cover41and prevents in particular that particles46, pre-separated due to the rotating flow, might still impact on the filter medium4, for example, due to effects of gravity.

After demounting the service cover41, the filter element3can be pulled out of the receiving section40. The filter element24remains in the receiving section40upon exchange or cleaning of the filter element3and ensures that the raw side RO and the clean side RL remain separated from each other by means of the filter medium25. Since the sealing device31projects outwardly in the radial direction R, an outflow cross section of the filter element3is not constricted by the sealing device31. Preferably, the sealing device31projects in the mounted state at least in sections, in particular viewed along the short side38, radially past an inner wall surface of the filter medium4or the central tube5of the filter element3, at least however past the inner side of the open end disk7, i.e., as shown In the present embodiment past the inner side of the receiving opening11.

REFERENCE CHARACTERS

28A bottom section

28B support element

32A outer surface

32B inner surface

32C end face

42quick connect device

45particle discharge opening

49seal contact surface

51seal contact surface

a distance

A outflow direction

A1cross section surface

A2cross section surface

b width

br width direction

E inflow direction

h height

hr height direction

L fluid

M16curvature center point

M17curvature center point

M19curvature center point

M20curvature center point

M33curvature center point

M34curvature center point

M35curvature center point

M36curvature center point

R radial direction

RL clean side

RO raw side

R16radius of curvature

R17radius of curvature

R19radius of curvature

R20radius of curvature

R33radius of curvature

R34radius of curvature

R35radius of curvature

R36radius of curvature