FILTER SYSTEM AND FILTER ELEMENT

Description

Technical field

[0001] The present invention relates to a filter system and a filter element of such a filter system. State of the art

[0002] A filter system may comprise a filter housing and a filter element removably mounted in the filter housing, comprising a pleated filter medium. For supplying a fluid to be cleaned to the filter element, the filter housing includes a fluid inlet through which the fluid can flow laterally onto the filter medium. Such lateral flow may cause pulsations in the pleats of the filter medium. These pulsations can lead to noise generation. This must be avoided.

[0003] WO 2019 / 112560 A1 shows a filter arrangement in which a pleated filter element is covered by a barrier over a wide area to prevent deformation of the filter element.

[0004] DE 20 2005 001693 U1 describes a cylindrical filter insert of a liquid filter, which is surrounded by a covering layer running around a filter medium.

[0005] DE 10 2018 129695 A1 shows a filter element with a reinforcement band.

[0006] US 2016 / 0144310 A1 describes a filter system with a filter housing in which a filter element is arranged. The filter housing has a fluid inlet that is inclined such that the flow toward the filter element is oblique. Disclosure of the invention

[0007] Against this background, the present invention is based on the object of providing an improved filter system.

[0008] Accordingly, a filter system is proposed with a filter housing which comprises a fluid inlet for admitting fluid into the filter housing, and with a filter element which is removably received in the filter housing and which comprises a folded filter medium and a stabilizing ring which stabilizes the filter medium, wherein the stabilizing ring is attached to the filter medium in such a way that the stabilizing ring is arranged at least in sections within an inflow cross-section of the fluid inlet, wherein the fluid preferably flows directly against the filter medium during operation of the filter system, wherein the stabilizing ring is arranged centrally in the inflow cross-section, and wherein the fluid flows perpendicularly against the filter medium during operation of the filter system.

[0009] By arranging the stabilizing ring within the inflow cross-section, pulsations of the filter medium in the area of ​​the inflow cross-section can be advantageously prevented, as the folds of the filter medium are stabilized by the stabilizing ring. This leads to a reduction in noise.

[0010] The filter system is preferably an air filter system. Accordingly, the filter element is an air filter element. The filter system is suitable, for example, for cleaning air supplied to an air compressor. However, the filter system can also be used as an intake air filter for an internal combustion engine. The filter housing preferably comprises a pot-shaped lower housing section and an upper housing section that can be removed from the lower housing section. The filter element can be removed from the filter housing and replaced. The fluid inlet is preferably tubular. The fluid inlet is arranged laterally on the lower housing section. The fluid to be cleaned thus flows perpendicular to an axis of symmetry of the filter element against the filter medium. The inflow cross-section can also be referred to as the outflow cross-section.

[0011] The filter medium is preferably a zigzag-folded bellows. The filter medium can be cylindrical. The stabilizing ring is applied, in particular, to the outside of the filter medium and extends completely around the filter medium in a ring-like manner. In particular, the stabilizing ring is attached to pleat tips of folds of the filter medium. The fact that the stabilizing ring is arranged "inside" the inflow cross-section means, in this case, that the stabilizing ring is covered or overlapped by the inflow cross-section when viewed from the fluid inlet to the filter medium. The inflow cross-section can be circular. However, the inflow cross-section can have any other geometry.

[0012] The fact that the stabilizing ring is arranged "at least in sections" within the inflow cross-section can mean in this case that the stabilizing ring, which runs annularly around the filter medium, is only partially covered by the inflow cross-section when viewed in a circumferential direction. Viewed along a longitudinal direction, which is oriented from a first end plate of the filter element to a second end plate of the filter element, the stabilizing ring is preferably positioned entirely within the inflow cross-section.

[0013] The stabilization ring is arranged centrally in the inflow cross-section. "Centrally" is preferably understood here to mean along the aforementioned longitudinal direction. However, starting from an exactly central arrangement, the stabilization ring can be offset upwards or downwards by, for example, up to 15 mm, in particular up to 10 mm, relative to a central or symmetry axis of the fluid inlet.

[0014] In this case, "operation" of the filter system refers to its intended operation or use, in which the filter system filters the fluid with the aid of the filter element. The fact that the fluid flows "directly" against the filter medium during operation of the filter system means, in particular, that the fluid is not redirected or deflected before it flows against the filter medium. The fluid is thus guided to the filter element, in particular to the filter medium, without redirection or deflection. In particular, the fluid flows against the filter medium without redirection or deflection.

[0015] In particular, "direct" can also mean that the fluid impinges on the filter medium perpendicularly or flows perpendicularly against it. "Perpendicular" in this context is understood to mean, in particular, an angle of 90° ± 10°, preferably 90° ± 5°, more preferably 90° ± 3°, more preferably 90° ± 1°, and more preferably exactly 90°. In particular, the terms "perpendicular" and "essentially perpendicular" can be interchanged as desired. The fluid can thus impinge on the filter medium essentially perpendicularly.

[0016] An axis of symmetry of the fluid inlet runs through the stabilizing ring. In particular, the fluid inlet is designed rotationally symmetrically to the axis of symmetry. The stabilizing ring is arranged such that the axis of symmetry runs centrally through the stabilizing ring, viewed along the longitudinal direction.

[0017] The axis of symmetry of the fluid inlet is arranged perpendicular to a symmetry axis of the filter element. "Perpendicular" in this context is understood to mean an angle of preferably 90° ± 10°, more preferably 90° ± 5°, more preferably 90° ± -3°, more preferably 90° ± 1°, more preferably exactly 90°. The filter element is preferably constructed rotationally symmetrically to its axis of symmetry.

[0018] In embodiments, the filter element comprises a first end plate and a second end plate, wherein the filter medium is arranged between the first end plate and the second end plate, and wherein the stabilizing ring is arranged between the first end plate and the second end plate, in particular centrally or off-center between the first end plate and the second end plate. Preferably, the first end plate and the second end plate are glued to the filter medium or cast onto it. "Off-center" in this context means that the stabilizing ring is positioned either closer to the first end plate than to the second end plate or closer to the second end plate than to the first end plate.

[0019] In some embodiments, exactly one stabilizing ring is provided. Alternatively, multiple stabilizing rings may be provided, with at least one of the stabilizing rings being arranged within the inflow cross-section of the fluid inlet.

[0020] In some embodiments, the stabilizing ring is glued to the filter medium. In particular, the stabilizing ring is glued to the pleat tips of the filter medium. With the help of the stabilizing ring, the pleat tips can be held evenly spaced from each other.

[0021] In embodiments, the stabilizing ring comprises a band, a cord, and / or a hot-melt adhesive. The stabilizing ring is, for example, a band or cord glued to the filter medium. For example, the stabilizing ring can be an adhesive bead or glue bead that completely encircles the axis of symmetry of the filter element, or the like. In particular, the stabilizing ring can comprise threads impregnated with hot-melt adhesive, for example, at least three such threads, or a band impregnated with hot-melt adhesive.

[0022] In some embodiments, the filter element has a circular-cylindrical or oval cross-section. If the filter element is oval, it is preferably not rotationally symmetrical to the axis of symmetry. The filter element can, in principle, have any geometry in cross-section.

[0023] During operation of the filter system, the fluid flows perpendicularly against the filter medium. As previously mentioned, during operation of the filter system, the fluid can also flow essentially perpendicularly against the filter medium. In particular, during operation of the filter system, the fluid flows perpendicular to the symmetry axis of the filter element against the filter medium.

[0024] In some embodiments, the fluid flows through the inflow cross-section against the filter medium during operation of the filter system. The fluid thus enters the filter housing, particularly through the inflow cross-section.

[0025] In embodiments, the fluid flows radially into the filter housing and / or radially onto the filter element or filter medium through the inflow cross-section during operation, as viewed in the longitudinal direction. For this purpose, the fluid inlet is preferably arranged radially on the filter housing. Likewise, the fluid inlet, preferably the entire cross-section of the fluid inlet, can preferably be arranged axially with respect to the longitudinal direction of the filter element and / or filter housing between the axial ends or, if appropriate, between two end plates of the filter element.

[0026] Furthermore, a filter element of such a filter system is proposed. As previously mentioned, the filter element is, in particular, an air filter element. The filter element comprises the first end plate and the second end plate, between which the filter medium is arranged. Short description of the drawings

[0027] It shows: Fig. 1: a schematic plan view of an embodiment of a filter system; Fig. 2: a further schematic plan view of the filter system according to Fig. 1 ; Fig. 3: a schematic sectional view of the filter system according to the section line III-III of the Fig. 1 ; Fig. 4: another schematic sectional view of the filter system according to the section line IV-IV of Fig. 2 ; Fig. 5: another schematic sectional view of the filter system according to the section line IV-IV of Fig. 2 ; Fig. 6: another schematic sectional view of the filter system according to the section line IV-IV of Fig. 2 ; Fig. 7: the detailed view VII according to Fig. 3 ; Fig. 8: the detailed view IIX according to Fig. 6 ; Fig. 9: a schematic perspective view of an embodiment of a filter housing for the filter system according to Fig. 1 ; Fig. 10: a schematic perspective view of an embodiment of a filter element for the filter system according to Fig. 1; and Fig. 11: a schematic side view of the filter element according to Fig. 10 .

[0028] In the figures, identical or functionally identical elements have been given the same reference numerals unless otherwise stated. Embodiment(s) of the invention

[0029] Fig. 1 shows a schematic plan view of an embodiment of a filter system 1. Fig. 2 shows another schematic top view of the filter system 1. Fig. 3 shows a schematic sectional view of the filter system 1 according to the section line III-III of the Fig. 1 . Fig. 4 shows a further schematic sectional view of the filter system 1 according to the section line IV-IV of the Fig. 2 . Fig. 5 shows a further schematic sectional view of the filter system 1 according to the section line IV-IV of the Fig. 2 . Fig. 5 shows a further schematic sectional view of the filter system 1 according to the section line IV-IV of the Fig. 2 . Fig. 6shows a further schematic sectional view of the filter system 1 according to the section line IV-IV of the Fig. 2 . Fig. 7 shows the detailed view VII according to Fig. 3 . Fig. 8 shows the detailed view IIX according to Fig. 6 . Fig. 9 shows a schematic perspective view of an embodiment of a filter housing 2 for the filter system 1. Fig. 10 shows a schematic perspective view of an embodiment of a filter element 3 for the filter system 1. Fig. 11 shows a schematic side view of the filter element 3. The following Fig. 1 to 11 referred to at the same time.

[0030] The filter system 1 can also be referred to as a filter arrangement. The filter system 1 is preferably used as an intake air filter for compressed air compressors. Alternatively, however, the filter system 1 can also be used as an intake air filter for internal combustion engines, for example in motor vehicles, trucks, construction vehicles, watercraft, rail vehicles, agricultural machinery or vehicles, or aircraft. The filter system 1 can also be used in immobile applications, for example in building technology. The filter element 3 is particularly suitable for filtering intake air of an air compressor. The filter element 3 is preferably an air filter element.

[0031] The filter element 3 is constructed rotationally symmetrically to a central or symmetry axis 4. The filter element 3 comprises a cylindrical filter medium 5. The filter medium 5 is constructed rotationally symmetrically to the symmetry axis 4. For example, the filter medium 5 can be annularly closed and in the form of a star-shaped pleated filter bellows. The filter medium 5 is thus preferably pleated.

[0032] The folded filter medium 5 can be provided with a stabilizing ring 6 for stabilizing the same. The stabilizing ring 6 can also be referred to as a fixing wrap. The stabilizing ring 6 is, for example, a tape or a cord glued to the filter medium 5. The stabilizing ring 6 can be an adhesive bead or glue bead or the like that completely encircles the filter medium 5 around the axis of symmetry 4. In particular, the stabilizing ring 6 can have a hot melt adhesive and / or hot melt adhesive-impregnated threads, for example at least three such threads. The stabilizing ring 6 serves to stabilize folds of the folded filter medium 5 and thus keep their distance from one another constant. The stabilizing ring 6 is placed off-center on the filter medium 5, viewed along a longitudinal direction LR of the filter element 3.A central positioning would also be conceivable; in this case, a positioning of the air inlet 29 or the axis of symmetry 30 at the same axial position with respect to the longitudinal direction LR would be preferred (analogous to . Fig. 7 ).

[0033] The longitudinal direction LR is oriented along the symmetry axis 4. In the orientation of the Fig. 11The longitudinal direction LR can be oriented from bottom to top. However, the longitudinal direction LR can also be oriented the other way around. The stabilizing ring 6 is provided on the outside of the filter medium 5. "Off-center" in this case means that the stabilizing ring 6 is not arranged centrally between the two end faces 7, 8 with respect to a first end face 7 and a second end face 8 of the folded filter medium 5, but is placed, for example, closer to the first end face 7 than to the second end face 8. In particular, exactly one stabilizing ring 6 is provided, which completely encircles the axis of symmetry 4 in an annular manner.

[0034] The filter medium 5 is, for example, a filter paper, a filter fabric, a filter scrim, or a filter fleece. In particular, the filter medium 5 can be produced using a spunbond or meltblown process or comprise such a fiber layer applied to a fleece or cellulose carrier. Furthermore, the filter medium 5 can be felted or needled. The filter medium 5 can comprise natural fibers, such as cellulose or cotton, or synthetic fibers, for example made of polyester, polyvinyl sulfite, or polytetrafluoroethylene. Fibers of the filter medium 5 can be oriented in, obliquely and / or transversely or randomly to a machine direction during processing.

[0035] The filter element 3 has a first, in particular open, end plate 9, which is provided on the first end face 7 of the filter medium 5. The filter element 3 further comprises a second, in particular closed, end plate 10, which is provided on the second end face 8 of the filter medium 5. This means that the filter medium 5 is placed between the first end plate 9 and the second end plate 10. The end plates 9, 10 can be made, for example, from a polyurethane material, in particular cast in casting shells, preferably foamed. The end plates 9, 10 can be cast onto the filter medium 5. The first end plate 9 is connected to the first end face 7. The second end plate 10 is connected to the second end face 8.

[0036] The first end plate 9 comprises a centrally arranged opening 11. The opening 11 can be an outflow opening of the filter element 3. The first end plate 9 comprises a plate-shaped base section 12, which is connected to the first end face 7 of the filter element 3. The opening 11 penetrates the base section 12. A plurality of grooves or recesses 13 can be provided on the outside of the base section 12, which are arranged evenly distributed around the axis of symmetry 4.

[0037] A positioning and sealing section 14 of the first end plate 9, extending annularly around the axis of symmetry 4, extends from the base section 12, facing away from the first end face 7 of the filter medium 5. With the aid of the positioning and sealing section 14, the filter element 3 can be positioned in the filter housing 2 and sealed relative thereto, as explained below. The opening 11 also penetrates the positioning and sealing section 14.

[0038] On the outside, i.e. facing away from the opening 11, a plurality of positioning recesses 15 are provided on the positioning and sealing section 14, of which Fig. 10 and 11only one is provided with a reference symbol. The positioning recesses 15 are arranged evenly distributed around the axis of symmetry 4. For example, six such positioning recesses 15 are provided. However, the number of positioning recesses 15 is arbitrary. Starting from an annular end face 16 of the positioning and sealing section 14, the positioning recesses 15 have a depth t15 when viewed along the axis of symmetry 4 or along the longitudinal direction LR ( Fig. 8 ). The positioning recesses 15 extend from the end face 16 in the direction of the base section 12.

[0039] How Fig. 8As further shown, the first end plate 9 or the positioning and sealing section 14 has, on its inside, i.e., facing the opening 11, a cylindrical sealing surface 17 which is rotationally symmetrical to the axis of symmetry 4 and completely surrounds it. The sealing surface 17 is suitable for interacting with the filter housing 2 in order to form a fluid-tight seal between the first end plate 9 and the filter housing 2. In this case, the sealing surface 17 can be compressed radially. "Radial" here means in a radial direction R, which is oriented perpendicular to the axis of symmetry 4 and points away from it.

[0040] The sealing surface 17 extends from the end face 16 along the longitudinal direction LR by a depth t17 into the opening 11. The sealing surface 17 is followed by an annular groove or sealing groove 18 which runs annularly around the axis of symmetry 4. Starting from the end face 16 along the longitudinal direction LR, the sealing groove 18 ends at a depth t18. The depth t18 is smaller than the depth t15. The depth t17 is smaller than the depth t15. Viewed along the longitudinal direction LR, the sealing groove 18 is followed by a cylindrical surface 19 which runs annularly around the axis of symmetry 4. Viewed in the radial direction R, the sealing surface 17 has a smaller diameter than the surface 19. The sealing surface 17, sealing groove 18 and the surface 19 form a sealing interface or interface 20 of the filter element 3. The interface 20 can also be referred to as the first interface or as the filter element interface.The interface 20 is suitable for interacting with the filter housing 2. The interface 20 has a depth t20 starting from the end face 16 of the positioning and sealing section 14. The interface 20 can also include the positioning recesses 15.

[0041] Now returning to Fig. 11 The second end plate 10 has a plate-shaped base section 21, which is rotationally symmetrical to the axis of symmetry 4 and seals the second end face 8 of the filter medium 5 in a fluid-tight manner. Positioning elements 22 extend from the base section 21, facing away from the second end face 8, of which Fig. 11 only one is provided with a reference symbol. The number of positioning elements 22 is arbitrary. For example, five such positioning elements 22 can be provided, which are arranged evenly distributed around the axis of symmetry 4.

[0042] The function of the filter element 3 is explained below using Fig. 3 explained. Fluid L to be cleaned, for example air, passes from a raw side RO of the filter element 3 through the filter medium 5 to a clean side RL of the filter element 3 surrounded by the filter medium 5. This means that the fluid L flows through the filter medium 5 into an interior space 23 of the filter element 3 surrounded by the filter medium 5. The cleaned fluid L flows out of the filter element 3 through the opening 11 of the first end plate 9 as filtered fluid L.

[0043] Returning now to the filter housing 2, this comprises a lower housing part 24 and an upper housing part 25. The upper housing part 25 can also be referred to as a housing cover. The upper housing part 25 can be removed from the lower housing part 24 and re-installed thereon to replace the filter element 3. A sealing element, for example in the form of an O-ring, can be provided between the lower housing part 24 and the upper housing part 25. The upper housing part 25 can have quick-release fasteners 26, of which Fig. 1 only one is provided with a reference symbol. The number of quick-release fasteners 26 is arbitrary. For example, three such quick-release fasteners 26 are provided, which are arranged evenly distributed around the axis of symmetry 4.

[0044] With the help of the quick-release fasteners 26, the upper housing part 25 can be detachably connected to the lower housing part 24. For this purpose, engagement sections, for example in the form of hooks or shoulders, can be provided on the lower housing part 24, into which engagement sections the quick-release fasteners 26 engage in a form-fitting manner to connect the upper housing part 25 to the lower housing part 24. A form-fitting connection is created by the interlocking or engaging of at least two connection partners, in this case the quick-release fasteners 26 and engagement sections. The upper housing part 25 further comprises engagement sections which can interact with the positioning elements 22 of the second end plate 10 of the filter element 3 in such a way that the positioning elements 22 engage in a form-fitting manner in the engagement sections of the upper housing part 25. For example, the upper housing part 25 is a plastic injection-molded component.

[0045] The housing lower part 24 is cup-shaped and comprises a cylindrical base section 27, which is rotationally symmetrical to the axis of symmetry 4. The base section 27 is closed at the front by means of a base section 28. The base section 27 and base section 28 are formed as one piece, in particular from a single material. "One piece" or "one piece" in this case means that the base section 27 and base section 28 form a common component and are not composed of different individual components. "One piece" in this case means that the base section 27 and base section 28 are made entirely of the same material. For example, the housing lower part 24 is a plastic injection-molded component.

[0046] The lower housing part 24 comprises a fluid inlet 29, which is tubular. The fluid inlet 29 is constructed rotationally symmetrically to a central or symmetry axis 30. The symmetry axis 30 is positioned perpendicular to the symmetry axis 4. The fluid L to be cleaned can be supplied to the filter element 3 on the raw side through the fluid inlet 29. Furthermore, the lower housing part 24 comprises a fluid outlet 31, which is provided on the base section 28. The fluid outlet 31 is tubular and constructed rotationally symmetrically to the symmetry axis 4. The cleaned fluid L can be discharged from the filter element 3 through the fluid outlet 31.

[0047] The fluid outlet 31 extends from the bottom section 28 of the lower housing part 24 outwards in the direction away from the filter element 3. Furthermore, as an extension of the fluid outlet 31, it extends into an interior space 32 ( Fig. 3 to 6 ) of the lower housing part a tubular interface 33 ( Fig. 8), which interacts with the interface 20 of the filter element 3 to seal the filter element 3 against the housing lower part 24. The interface 33 is tubular and rotationally symmetrical to the axis of symmetry 4. The interface 33 can also be referred to as a second interface or as a filter housing interface.

[0048] On the inside of the interface 33, i.e., facing away from the interface 20 of the filter element 3, an interfering contour 34 is provided at the interface 33. The interfering contour 34 is formed, for example, as a plurality of grooves extending along the longitudinal direction LR. The interfering contour 34 prevents a filter element not belonging to the filter system 1 from being mounted at the interface 33, which would form a radial seal on the inside with respect to the interface 33.

[0049] As previously mentioned, the interface 33 extends from the base portion 28 into the interior space 32 of the housing lower part 24. The interface 33 comprises a cylindrical sealing surface 35, which is rotationally symmetrical to the axis of symmetry 4 and interacts with the sealing surface 17 of the filter element 3. In particular, the sealing surfaces 17, 35 are radially pressed together when viewed in the radial direction R.

[0050] Viewed along the longitudinal direction LR, the sealing surface 35 is adjoined by a nose or sealing rib 36 extending annularly around the axis of symmetry 4. The sealing rib 36 is suitable for positively engaging the sealing groove 18 of the interface 20. Viewed in the longitudinal direction LR, after the sealing rib 36, a cylindrical centering surface 37 is provided. The centering surface 37 is suitable for centering or guiding the sealing surface 17 of the filter element 3 with respect to the axis of symmetry 4 during installation of the filter element in the lower housing part 24. A gap 38, in particular an air gap, is provided between the surface 19 and the centering surface 37.

[0051] How Fig. 9 shows, interference geometries 39 are provided on the bottom section 28 of the lower housing part 24, of which Fig. 9only one is provided with a reference symbol. For example, three or five such interference geometries 39 are provided, which are evenly distributed around the axis of symmetry 4. The number of interference geometries 39 is arbitrary. The interference geometries 39 are suitable for positively engaging the positioning recesses 15 of the first end plate 9. The interference geometries 39 protrude from the base section 28 into the interior space 32. The interference geometries 39 also prevent the installation of a filter element that does not fit the filter system 1 and does not have positioning recesses 15 in the housing base 24.

[0052] From a frontal area 40 ( Fig. 8) of the base section 28, against which the end face 16 rests, each interference geometry 39 has a depth t39 when viewed along the longitudinal direction LR. The depth t39 is greater than the depth t18 and smaller than the depth t15. Each interference geometry 39 comprises an end face 41 that is oriented parallel to the end face 40 and arranged at a distance from it. The base section 12 of the first end plate 9 comprises an end face 42. End faces 41, 42 are positioned parallel to one another and at a distance from one another.

[0053] Centering geometries 43 are also formed in the lower housing part 24, of which Fig. 2 , 9 only one of each is provided with a reference symbol. For example, three or five such centering geometries 43 may be provided, which are evenly distributed around the axis of symmetry 4. Each centering geometry 43 comprises an upper edge 44 inclined at an angle to the axis of symmetry 4.

[0054] The installation of the filter element 3 into the filter housing 2 is described below using Fig. 4 to 6 and 8. First, the filter element 3 is inserted into the housing base 24 in an insertion direction E, which is oriented along the axis of symmetry 4. The insertion direction E is oriented from the second end plate 10 in the direction of the first end plate 9. The longitudinal direction LR and the insertion direction E can be oriented in opposite directions. In this case, the filter element 3 is pre-centered using the plate-shaped base section 12 of the first end plate 9 at the centering geometries 43. With the help of the centering geometries 43, the filter element 3 is centered with respect to the axis of symmetry 4, so that the end face 16 of the positioning and sealing section 14 of the first end plate 9 rests on the end faces 41 of the interference geometries 39 ( Fig. 5 ). This means that the interfaces 20, 33 are not yet in engagement with each other.

[0055] From the Fig. 5 In the position shown, the filter element 3 can now be rotated about the axis of symmetry 4 until the interfering geometries 39 are aligned with the positioning recesses 15 of the positioning and sealing section 14, so that the filter element 3 can be pressed further into the housing base 24 along the insertion direction E. When the filter element 3 is rotated about the axis of symmetry 4, the sealing surface 17 of the first end plate 9 is guided on the centering surface 37 of the interface 33 and centered with respect to the axis of symmetry 4. As soon as the interfering geometries 39 engage in the positioning recesses 15, the positioning and sealing section 14 is elastically deformed such that the sealing rib 36 engages positively in the sealing groove 18. At the same time, the sealing surfaces 17, 35 are pressed radially against one another. The end faces 16, 40 lie against one another. The filter element 3 is mounted in the lower housing part 24.

[0056] The filter system 1 further comprises a silencer 45 ( Fig. 1 to 3 and 7 ), which is attached to the fluid inlet 29. The silencer 45 is preferably a one-piece, in particular a one-piece, plastic component. The silencer 45 can be a plastic injection-molded component. The silencer 45 is constructed rotationally symmetrically to the axis of symmetry 30. The silencer 45 has a plurality of fluid guide ribs 46 on the outside, which run parallel to the axis of symmetry 30. The fluid guide ribs 46 are provided on the outside of a tubular base body 47 of the silencer 45. The fluid L to be cleaned is fed to the filter element 3 through the silencer 45.

[0057] The base body 47 has a frustoconical inlet 48 and a likewise frustoconical outlet 49. The inlet 48 and outlet 49 are fluidically connected to one another. The inlet 48 and outlet 49 are arranged such that the frustoconical geometries are positioned such that a cross-sectional constriction 51 rounded by a rounded portion 50 results between the inlet 48 and outlet 49. The inlet 48 faces away from the fluid inlet 29. The outlet 49 faces the fluid inlet 29. The inlet 48 and outlet 49 together thus form an hourglass-shaped or trumpet-shaped geometry. The outlet 49 has an inflow cross-section A of the fluid inlet. The flow against the filter medium 5 occurs at the inflow cross-section A.

[0058] Furthermore, an inlet rounding 52 is provided on the inlet 48, which runs completely around the axis of symmetry 30. The inlet rounding 52 runs completely around an inlet opening 53 of the base body 47. The base body 47 merges into a tubular fastening section 54. The fastening section 54 can have snap hooks 55, with the aid of which the silencer 45 is positively connected to the fluid inlet 29. Between the fastening section 54 and the base body 47, a rib 56 is provided, which runs completely around the axis of symmetry 30. The rib 56 is arranged perpendicular to the axis of symmetry 4. The rib 56 is received in the fluid inlet 29. The fluid guide ribs 46 are provided on an outer side 57 ( Fig. 1 and 2 ) of the base body 47. The outlet 49 has an outlet opening 58. A diameter of the outlet opening 58 is smaller than a diameter of the inlet opening 53.

[0059] During operation of the filter system 1, the fluid L to be filtered is sucked laterally around the inlet rounding 52 into the inlet opening 53 and thus into the inlet 48, as shown in Fig. 7 indicated by arrows 59, 60. The fluid L thus flows along the fluid guide ribs 46, which guide the fluid to the inlet 48. The fluid L flows through the base body 47 along a, in particular first, flow direction SR1. The flow direction SR1 is oriented from the inlet opening 53 toward the filter element 3. The fluid guide ribs 46 run along or parallel to the flow direction SR1.

[0060] The fluid L flows on the outside of the base body 47 along the fluid guide ribs 46 in one, in particular a second, flow direction SR2. The flow directions SR1, SR2 are oriented in opposite directions. The flow direction SR2 is oriented along the radial direction R. The flow direction SR1, however, is oriented opposite to the radial direction R. The fluid guide ribs 46 also run along the flow direction SR2.

[0061] Immediately upstream of the inlet 48, there is a region 61 in which the fluid L exhibits essentially no movement. This means that the fluid L to be filtered is essentially only sucked along the fluid guide ribs 46 in the direction of the inlet rounding 52 and around it into the inlet 48. The sucked-in fluid L impacts the filter medium 5, with the stabilizing ring 6 preventing any movement of the folds of the folded filter medium 5. The stabilizing ring 6 is positioned centrally in the inflow cross-section A of the fluid inlet 29, viewed along the longitudinal direction LR.

[0062] In particular, the filter medium 5 is protected from pulsations by means of the stabilizing ring 6. This results in noise reduction. The stabilizing ring 6 is arranged centrally with respect to the silencer 45. This means that the axis of symmetry 30 preferably runs centrally through the stabilizing ring 6. The double conical shape of the inlet 48 and outlet 49 ensures noise reduction. Reference symbol

[0063] 1 Filter system 2 Filter housing 3 Filter element 4 Axis of symmetry 5 Filter medium 6 Stabilization ring 7 End face 8 End face 9 End plate 10 End plate 11 Opening 12 Base section 13 Recess 14 Positioning and sealing section 15 Positioning recess 16 End face 17 Sealing surface 18 Sealing groove 19 Surface 20 Interface 21 Base section 22 Positioning element 23 Interior 24 Housing base 25 Housing top 26 Quick release 27 Base section 28 Bottom section 29 Fluid inlet 30 Axis of symmetry 31 Fluid outlet 32 ​​Interior 33 Interface 34 Interference contour 35 Sealing surface 36 Sealing rib 37 Centering surface 38 Gap 39 Interference geometry 40End face 41End face 42End face 43Centering geometry 44Top edge 45Silencer 46Fluid guide ribs 47Base body 48Inlet 49Outlet 50Rounding 51Cross-sectional constriction 52Inlet rounding 53Inlet opening 54Fastening section 55Snap hook 56Rib 57Outside 58Outlet opening 59Arrow 60Arrow 61Area A Flow cross-section E Inlet direction L Fluid LR Longitudinal direction R Radial direction RLR Clean side ROR Raw side SR1 Flow direction SR2 Flow direction t15 Depth t17 Depth t18 Depth t20 Depth t39 Depth

Claims

1. A filter system (1) having a filter housing (2) comprising a fluid inlet (29) for allowing fluid (L) to enter the filter housing (2), and a filter element (3) removably accommodated in the filter housing (2), said filter element comprising a folded filter medium (5) and a stabilization ring (6) stabilizing the filter medium (5), wherein the stabilization ring (6) is attached to the filter medium (5) such that the stabilization ring (6) is disposed at least section-wise inside an inflow cross-section (A) of the fluid inlet (29), wherein the fluid (L) flows directly towards the filter medium (5) during operation of the filter system (1), wherein the stabilization ring (6) is disposed centrally in the inflow cross-section (A), wherein the fluid (L) flows perpendicularly against the filter medium (5) during operation of the filter system (1), wherein a symmetry axis (30) of the fluid inlet (29) extending through the stabilization ring (6), and wherein the symmetry axis (30) of the fluid inlet (29) is disposed perpendicularly to a symmetry axis (4) of the filter element (3).

2. The filter system according to claim 1, wherein the filter element (3) comprises a first end disc (9) and a second end disc (10), wherein the filter medium (5) is disposed between the first end disc (9) and the second end disc (10), and wherein the stabilization ring (6) is disposed centrally or eccentrically between the first end disc (9) and the second end disc (10).

3. The filter system according to claim 1 or 2, wherein precisely one stabilization ring (6) is provided.

4. The filter system according to one of the claims 1 to 3, wherein the stabilization ring (6) is glued to the filter medium (1).

5. The filter system according to claim 4, wherein the stabilization ring (6) comprises a tape, a cord and / or a hot-melt adhesive.

6. The filter system according to one of the claims 1 to 5, wherein the filter element (3) is circular-cylindrical or oval in cross-section.