Filter element and filter arrangement

Abstract

A filter element (3), which has an oval cross-section in a longitudinal direction (LR) thereof and includes a circumferential sealing device (10) for, in particular, radially sealing the filter element (3) off from a filter holder (2) for the filter element (3), wherein the sealing device (3) has two first curvature sections (35, 36) arranged one facing the other and two second curvature sections (38, 39) arranged one facing the other, wherein the first curvature sections (35, 36) each have a first radius of curvature (R35, R36) and the second curvature sections (38, 39) each have a second radius of curvature (R38, R39), and wherein the first radius of curvature (R35, R36) differs from the second radius of curvature (R38, R39).

Claims

1. A filter element (3), comprising: an oval filter body (4) of filter medium elongated in a longitudinal direction (LR) having a central axis (MA) arranged extending through a center of the oval filter body (4), the oval filter body having: an outer circumferential contour (29) of the oval filter body (4) of filter medium is formed by: curvature contour sections; and partially straight or slightly curved contour sections; wherein the curvature contour sections include: a first curvature contour section and a second curvature contour section are convex and have a first radius curvature, wherein the first curvature contour section and the second curvature contour section form opposite sides of the outer circumferential contour of the oval filter body (4) of filter medium; wherein the partially straight or slightly curved contour sections include: a first partially straight or slightly curved contour section and a second partially straight or slightly curved contour section, wherein the first radius of curvature of the curvature contour sections is less than a radius of curvature of the partially straight or slightly curved contour sections; wherein the first partially straight or slightly curved contour section and the second partially straight or slightly curved contour section form opposite sides of the outer circumferential contour of the oval filter body (4) of filter medium; a first end plate (7) having radially inner contour forming a receiving opening (11) extending through the first end plate (7), the first end plate (7) secured to a first axial end of the oval filter body (4); a circumferential sealing device (4) arranged on outer surface (9) of the first end plate, between the radially outer contour of the first end plate and the radially inner contour of the first end plate, the circumferential sealing device (4) configured to radially seal the filter element (10) off from a filter holder (2) into which the filter element (3) is receivable, wherein the sealing device (3) has: two first sealing device curvature sections (35, 36) arranged one facing the other; and two second sealing device curvature sections (38, 39) arranged one facing the other, wherein the first sealing device curvature sections (35, 36) each have a first radius of curvature (R35, R36), wherein the second sealing device curvature sections (38, 39) each have a second radius of curvature (R38, R39), wherein the second radius of curvature of the second sealing device curvature sections is larger than the first radius of curvature of the first sealing device curvature sections (35, 36), and wherein the two second sealing device curvature sections are each arranged between and connected at opposing ends to adjacent ones of the two first sealing device curvature sections, forming a continuous materially integral oval sealing device surrounding the radially inner contour of the first end plate.

2. The filter element according to claim 1, wherein the second radius of curvature of the second sealing device curvature sections is smaller than the radius of curvature of the partially straight or slightly curved contour sections of the oval filter body.

3. The filter element according to claim 1, wherein at least one of the first sealing device curvature sections (35,35) has a center portion that protrudes radially outwardly on the outer surface of the first end plate to have a smallest distance to the radially outer contour of the first end plate or to the outer circumferential contour of the filter body, compared to other sealing device curvature sections.

4. The filter element according to claim 1, wherein the centers of curvature (M35, M36) of the first radii of curvature (R35, R36) of the two first sealing device curvature (35,36) sections are arranged on a first straight line (37); wherein the centers of curvature (M38, M39) of the second radii of curvature (R38, R39) of the two second sealing device curvature (35,35) sections are arranged on a second straight line (40); and wherein the first straight line (37) is positioned so as to be perpendicular to the second straight line (40).

5. The filter element according to claim 4, wherein the second straight line (40) is arranged centrally between the centers of curvature (M35, M36) of the first radii of curvature (R35, R36) of the two first sealing device curvature (35,35) sections; and/or the first straight line (37) is arranged centrally between the centers of curvature (M38, M39) of the second radii of curvature (R38, R39) of the two second sealing device curvature (35,35) sections.

6. The filter element according to claim 1, wherein the sealing device (10) has an outer contour (41) and/or an inner surface (43) or sealing surface is arranged so as not to be parallel to the radially outer contour (42) of the first end plate (7) and/or the outer circumferential contour an outer surface (29) of the filter body (4).

7. The filter element according to claim 1, wherein the filter element (3) comprises: an inflow protector (12) arranged circumferentially enclosing the outer circumferential contour of the oval filter body (4) over at least a portion of an axial length of the oval filter body.

8. The filter element according to claim 7, wherein the inflow protector (12) is adhesively fixed onto, welded onto, or fused onto the oval filter body (4) and/or the first end plate (7).

9. The filter element according to claim 7, wherein the inflow protector (12) is fluid-tight, impermeable to fluid flow through the inflow protector.

9. The filter element according to claim 7, wherein the inflow protector (12) runs annularly about an exterior of the filter body (4).

10. The filter element according to claim 1, wherein the second sealing device curvature sections (38, 39) are more curved than a comparison curve (VK) that can be compared with respect to the position thereof on the first end plate (7) and is substantially parallel and concentric to the radially inner and/or the radially outer contour (42) of the first end plate (7) and/or the oval filter body (4).

11. The filter element according to claim 1, wherein the second sealing device curvature sections (38, 39) are more curved than the radially inner and/or the radially outer contour (42) of the first end plate (7) and/or the oval filter body (4) in the region of the second sealing device curvature sections (38, 39).

12. The filter element according to claim 1, wherein the second sealing device curvature sections (38, 39) are more curved than the radially inner and the radially outer contour (42) of the first end plate (7) and/or the oval filter body (4) in the region of the second sealing device curvature sections (38, 39).

13. The filter element according to claim 1, wherein the first sealing device curvature sections are connected to one another by the second sealing device curvature sections in such a manner that the first and second sealing device curvature sections each merge continuously into one another.

14. The filter element according to claim 1, wherein the oval filter body has an oval cross section defined by the filter medium of the oval filter body; wherein the sealing device (10) is arranged within an imaginary axial continuation of the outer circumferential contour of the oval filter body (29) and/or the oval cross-section of the filter body (4) and/or the radially outer contour (42) of the first an open end plate (7) in the longitudinal direction (LR).

15. The filter element according to claim 1, wherein the sealing device (10) which has a seal inner surface (43) in the middle of less-curved curvature sections of the oval filter body and/or of the sealing device (10) which has a smaller distance to the outer circumferential contour (29) of the oval filter body (4) and/or the radially outer contour (42) of the first end plate (7) than in a transitional region between the more- and less-curved curvature sections of the oval filter body and/or the sealing device.

16. A filter arrangement (1), comprising a filter holder (2) having a holding section (19); and a filter element (3) held in the holding section (19) of the filter holder (2), the filter element including: an oval cross-section in a longitudinal direction (LR) thereof; an oval filter body (4) of filter medium elongated in a longitudinal direction (LR) having a central axis (MA) arranged extending through a center of the oval filter body (4), the oval filter body having: an outer circumferential contour (29) of the oval filter body (4) of filter medium is formed by: curvature contour sections; and partially straight or slightly curved contour sections; wherein the curvature contour sections include: a first curvature contour section and a second curvature contour section are convex and have a first radius curvature, wherein the first curvature contour section and the second curvature contour section form opposite sides of the outer circumferential contour of the oval filter body (4) of filter medium; wherein the partially straight or slightly curved contour sections include: a first partially straight or slightly curved contour section and a second partially straight or slightly curved contour section, wherein the first radius of curvature of the curvature contour sections is less than a radius of curvature of the partially straight or slightly curved contour sections; wherein the first partially straight or slightly curved contour section and the second partially straight or slightly curved contour section form opposite sides of the outer circumferential contour of the oval filter body (4) of filter medium; a first end plate (7) having radially inner contour forming a receiving opening (11) extending through the first end plate (7), the first end plate (7) secured to a first axial end of the oval filter body (4); a circumferential sealing device (4) arranged on outer surface (9) of the first end plate, between the radially outer contour of the first end plate and the radially inner contour of the first end plate, the circumferential sealing device (4) configured to radially seal the filter element (10) off from a filter holder (2) into which the filter element (3) is receivable, wherein the sealing device (3) has: two first sealing device curvature sections (35, 36) arranged one facing the other; and two second sealing device curvature sections (38, 39) arranged one facing the other, wherein the first sealing device curvature sections (35, 36) each have a first radius of curvature (R35, R36), wherein the second sealing device curvature sections (38, 39) each have a second radius of curvature (R38, R39), wherein the second radius of curvature of the second sealing device curvature sections is larger than the first radius of curvature of the first sealing device curvature sections (35, 36), and wherein the two second sealing device curvature sections are each arranged between and connected at opposing ends to adjacent ones of the two first sealing device curvature sections, forming a continuous materially integral oval sealing device surrounding the radially inner contour of the first end plate.

17. The filter arrangement according to claim 16, wherein the holding section (19) comprises an engagement region (27), with which a circumferential sealing device (10) of the filter element (3) engages, and wherein the sealing device (10) rests against the engagement region (27) with an inner surface (43).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] FIG. 1 illustrates a schematic perspective view of one embodiment of a filter arrangement;

[0080] FIG. 2 illustrates a schematic view of the filter arrangement according to FIG. 1;

[0081] FIG. 3 illustrates a schematic view of the filter arrangement according to FIG. 1;

[0082] FIG. 4 illustrates schematic partial sectional view of the filter arrangement according to FIG. 1;

[0083] FIG. 5 illustrates schematic partial sectional view of the filter arrangement according to FIG. 1;

[0084] FIG. 6 illustrates a schematic perspective view of one embodiment of a filter element;

[0085] FIG. 7 illustrates a schematic perspective view of one embodiment of a secondary element;

[0086] FIG. 8 illustrates a schematic view of the filter arrangement according to FIG. 1;

[0087] FIG. 9 illustrates a schematic sectional view of the filter arrangement taken along the line IX-IX in FIG. 8;

[0088] FIG. 10 illustrates a schematic sectional view of the filter arrangement taken along the line X-X in FIG. 8;

[0089] FIG. 11 illustrates a schematic partial sectional view of the filter arrangement according to FIG. 1;

[0090] FIG. 12 illustrates a schematic perspective view of another embodiment of a filter arrangement;

[0091] FIG. 13 illustrates a schematic perspective view of another embodiment of a filter arrangement;

[0092] FIG. 14 illustrates a schematic perspective view of another embodiment of a filter element;

[0093] FIG. 15 illustrates a schematic sectional view of the filter element according to FIG. 14;

[0094] FIG. 16 illustrates a schematic view of the filter element according to FIG. 14;

[0095] FIG. 17 illustrates a schematic partial sectional view of the filter element according to FIG. 14;

[0096] FIG. 18 illustrates a schematic partial sectional view of another embodiment of a filter element;

[0097] FIG. 19 illustrates a schematic partial sectional view of another embodiment of a filter arrangement;

[0098] FIG. 20 illustrates a schematic perspective view of another embodiment of a filter arrangement;

[0099] FIG. 21 illustrates a schematic perspective partial sectional view of the filter arrangement according to FIG. 20;

[0100] FIG. 22 illustrates a schematic partial sectional view of the filter arrangement according to FIG. 20;

[0101] FIG. 23 illustrates a schematic sectional view of the filter arrangement according to FIG. 20;

[0102] FIG. 24 illustrates a schematic partial sectional view of the filter arrangement according to FIG. 20;

[0103] FIG. 25 illustrates a schematic view of the filter arrangement according to FIG. 20;

[0104] FIG. 26 illustrates a schematic perspective view of another embodiment of a filter arrangement;

[0105] FIG. 27 illustrates a schematic view of the filter arrangement according to FIG. 26;

[0106] FIG. 28 illustrates a schematic sectional view of the filter arrangement according to FIG. 26;

[0107] FIG. 29 illustrates a schematic sectional view of the filter arrangement according to FIG. 26;

[0108] FIG. 30 illustrates a schematic sectional view of the filter arrangement according to FIG. 26;

[0109] FIG. 31 illustrates a schematic sectional view of the filter arrangement according to FIG. 26; and

[0110] FIG. 32 illustrates a schematic partial sectional view of the embodiment of a filter arrangement according to FIG. 19, without depiction of the filter element.

[0111] In the drawings, identical or functionally-identical elementsunless otherwise specifiedhave been provided with identical reference signs.

DETAILED DESCRIPTION

[0112] FIG. 1 illustrates a schematic perspective view of one embodiment of a filter arrangement 1. FIG. 2 illustrates a front view of the filter arrangement 1. FIG. 3 illustrates a side view of the filter arrangement 1. FIGS. 4 and 5 each show a partial sectional view of the filter arrangement 1.

[0113] The filter arrangement 1 includes a filter holder 2, and a filter element 3 that is arranged in the filter holder 2. The filter holder 2 may also be referred to as a housing or filter housing. The filter element 3 is depicted in FIG. 6. The filter arrangement 1 is preferably used as an intake air filter for internal combustion engines, e.g. in motor vehicles, trucks, construction vehicles, watercraft, rail vehicles, agricultural machinery or vehicles, or aircraft. The filter element 3 is particularly suitable for filtering combustion air of an internal combustion engine. Preferably, the filter element 3 is an air filter element.

[0114] The filter element 3which may also be referred to as a primary element or main elementincludes a filter body 4 that surrounds a central tube 5 and preferably rests thereagainst in such a manner that the central tube 5 can be perceived as having a support function for the filter body when there is a flow therethrough. For example, the filter body 4 may be wound around the central tube 5 as a wrap made of a filter medium, or may rest thereagainst in an annularly-enclosed manner, for example, in the form of a star-shaped folded bellows. The central tube 5 is preferably in the shape of a grid and therefore fluid-permeable. The filter body 4 is preferably folded. For the purpose of stabilization, the folded filter medium can be wrapped around with a thread winding 6, i.e., a strip soaked in a hot melt adhesive or other adhesive, or can be fixed by means of a circularly- or helically-encircling adhesive beads. The filter medium is, for example, a filter paper, a filter fabric, a filter cloth, or a non-woven filter web. In particular, the filter medium can be produced in a spunbonded web or meltblown process, or can include such a fiber layer that has been applied to a spunbonded web or cellulose support. The filter medium may also be felted or needle-punched. The filter medium may include natural fiberssuch as cellulose or cottonor synthetic fiberssuch as polyester, polyvinyl sulfate, or polytetrafluoroethylene. The fibers, when processed, may be oriented in, oblique to, or transverse to the machine direction, or unordered.

[0115] The filter element 3 includes a first, in particular, open end plate 7 and a second, in particular, closed end plate 8. The end plates 7, 8 are preferably made from a plastic material. For example, the end plates 7, 8 may be configured as inexpensive plastic injection-molded components. The end plates 7, 8 may be produced, for example, from a polyurethane material, especially one that is molded in casting shells, and preferably one that is foamed. The end plates 7, 8 may be cast onto the filter body 4. The filter body 4 is arranged between the end plates 7, 8. A sealing device 10 for sealing the filter element 3 off from the filter holder 2 is provided on a front side 9 of the first end plate 7 that faces away from the filter body 4. The sealing device 10 is designed to seal the filter element 3 off from the filter holder 2, in particular, in a radial manner.

[0116] The filter medium of the filter body 4 may be fused, adhered, or welded to the end plates 7, 8. The second end plate 8 is, for example, plate-shaped and preferably fluid-impermeable. Provided in the first end plate 7 is a receiving opening 11 through which the air that has been filtered by the filter element 3 can continue to escape. The filter element 3 preferably further includes an inflow protector 12 that prevents a particle-laden fluid L from directly flowing into the filter medium 4. The fluid L may be air. The inflow protector 12 may be a foil, a small-meshed net, or a grid. The inflow protector 12 may be fluid-impermeable or fluid-permeable. The inflow protector 12 may be adhered, welded, or fused to the filter body 4. The inflow protector 12 is arranged adjacent to the first end plate 7. In particular, the inflow protector 12 borders on the first end plate 7. The inflow protector 12 may be connected to the first end plate 7, in particular, in a flow-sealed manner. Fluid L to be purified enters from a pre-filtration side RO of the filter element 3 through the filter body 4 into a cavity surrounded by the central tube 5, and flows therefrom through the receiving opening 11 as filtered fluid L to a post-filtration side RL of the filter element 3 that is surrounded, in particular, by the filter body 4.

[0117] The filter element 3 has, preferably, an oval cross-section in a longitudinal direction LR thereof. The cross-section may decrease from the first end plate 7 toward the second end plate 8, such that the filter element 3 tapers conically. However, the filter element 3 preferably has an oval cross-section such as is illustrated in FIG. 6. This means that the filter element 3 is in the shape of a cylinder, with an oval base area. Oval may presently be understood to mean a shape that has a smooth, non-concave outer contour, i.e., continuously formed of convex and straight sections, preferably exclusively formed of convex sections; for example, a rectangular cross-section having rounded corners, an elliptical cross-section, or a cross-section formed of a plurality of arcs. It is preferable to use an oval outer contour or cross-section having a center point and two axes of symmetry intersecting at the center point. The filter element 3 and, in particular, the filter body 4 have a width b and a height h (FIG. 10). The width b is greater than the height h. Preferably, the width b is two to three times the height h; more preferably, the width b is 1.5 to three times the height h.

[0118] In the filter holder 2, surrounded by the filter element 3, a secondary element 13 illustrated in FIG. 7 may be held. Such secondary elements are used, in particular, as a security for instances where an operator opens the filter holder 2 while a machine is running and removes the filter element 3, e.g., in order to remove dust from or replace same. In particular, the filter element 3 may be referred to as a first filter element and the secondary element 13 may be referred to as a second filter element. Preferably, the secondary element 13 is held in the receiving opening 11. The secondary element 13 includes a filter medium 14 as well as a first end plate 15 and a second end plate 16.

[0119] The filter medium 14 is arranged between the end plates 15, 16. The filter medium 14 surrounds a grid-shaped central tube 17. The secondary element 13 has, like the filter element 3, a pre-filtration side RO and a post-filtration side RL. The first end plate 15 may include a sealing device 18 for sealing the secondary element 13 off from the filter holder 2. The sealing device 18 may be formed so as to be materially integral with the first end plate 15. The filter element 3 and the secondary element 13 can be held in the filter holder 2. The secondary element 13 includes a fluid outflow opening 51. The fluid outflow opening 51 may be referred to as a fluid outflow opening of the filter element 3. As illustrated in FIGS. 1 to 5, the filter holder 2 includes a holding section 19. The holding section 19 may be formed of a first housing part 20 and a second housing part 21. The housing parts 20, 21 may be connected to one another with fastening means 22, such as, for example, with bolts. The housing parts 20, 21 are preferably made out of a plastic material. Alternatively, the housing parts 20, 21 may be made from sheet metal, in particular, sheet steel. For example, the housing part 20, 21 may be configured as inexpensive injection-molded components. A sealing device, such as, for example, an O-ring can be provided between the housing parts 20, 21. Alternatively, the holding section 19 may be integrally formed. This means that the housing parts 20, 21 form an integral component.

[0120] The filter holder 2 further includes a maintenance cover 23 that can be removed from the holding section 19. The filter element 3 can be removed from the holding section 19 via the maintenance cover 23. The maintenance cover 23 can be connected to the holding section 19 with the aid of quick-action fasteners. A sealing device may be provided between the maintenance cover 23 and the holding section 19 FIGS. 2 and 3 illustrate the filter arrangement 1 in two different assembly situations, namely, in one lying and one standing.

[0121] The filter holder 2 or the holding section 19 includes a fluid inlet 24 for allowing the fluid L to be filtered to flow into the filter holder 2, and an, in particular, central fluid outlet 25 for allowing the fluid L, having been filtered with the aid of the filter element 3, to flow out from the filter holder 2. The fluid inlet 24 and the fluid outlet 25 are preferably configured so as to be tubular in shape. The fluid inlet 24 may have an oval cross-section, as illustrated in FIGS. 1, 3, and 4. With the aid of the oval cross-sectionthe wide expansion of which is preferably oriented in the direction of the longitudinal direction LRit is possible to achieve a lower initial pressure loss as compared to a circular cross-section. The fluid L to be filtered enters the fluid inlet 24 in an inflow direction E. The fluid outlet 25 preferably has a circular cross-section. The fluid L exits from the fluid outlet 25 in an outflow direction A, preferably parallel to the longitudinal direction LR of the filter element 3. The inflow direction E is oriented so as to be perpendicular to the outflow direction A.

[0122] A particle discharge opening 26 may be provided on the maintenance cover 23. The particle discharge opening 26 is preferably tubular in shape. Particles that have been pre-separated from the fluid L can be guided away from the filter holder 2 via the particle discharge opening 26. The particle discharge opening 26 may include a valve. The housing parts 20, 21 and/or the maintenance cover 23 may be reinforced with ribs. Provided in the filter holder 2in particular, in the holding section 19is a first engagement region 27 (FIG. 5), with which the sealing device 10 of the filter element 3 engages. This engagement region 27 preferably has a sealing contact surface against which the sealing device 10 can be in sealing contact. In the present embodiment, as preferably illustrated, there is provided a radially outwardly-facing sealing contact surface of an oval cylinder shape, which follows the course of the inner surface 43 (sealing surface) of the sealing device 10. A second engagement region 28, with which the sealing device 18 of the secondary element 13 engages, may also be provided on the holding section 19. This second engagement region 28 preferably also includes a sealing contact surface 280 (see FIG. 32), against which the sealing device 18 can come into sealing contact. In the present embodiment, as preferably illustrated, there is provided a radially outwardly-facing sealing contact surface 280 of an oval cylinder shape. The first housing part 20 may include the engagement regions 27, 28. The engagement regions 27, 28 may completely encircle the fluid outlet 25.

[0123] FIG. 8 illustrates the filter arrangement 1 in a schematic side view. As FIG. 9 illustrates in a schematic sectional view taken along the IX-IX line in FIG. 8, the fluid inlet 24 is arranged such that the inflow direction E of the fluid L is oriented in the direction of an outer surface 29 and perpendicular to the longitudinal direction LR of the filter element 3 arranged in the holding section 19. The outer surface 29 forms an envelope around the filter body 4. A cylindricalin particular, oval cylindricalshape of the filter element 3 is formed by the end plates 7, 8 and the outer surface 29. The fluid L to be filtered flows through the filter element 3, which can be held in the holding section 19, in such a manner that particles contained in the fluid L to be filtered are separated out with the aid of centrifugal force at a wall 30 of the filter holder 2 or the holding section 19. The holding section 19 thus acts as a centrifugal separator. In particular, the inflow direction E is oriented such that the fluid L to be filtered flows to the filter element 3 substantially tangentially. The holding section 19, in cross-section, preferably has a width direction br and a height direction hr. The width-to-height ratio br/hr is preferably at least 4:3, more preferably at least 3:2, in particular at least 2:1, and/or at most 6:1, preferably at most 4:1, particularly preferably at most 3:1 or 2:1. Ratios lower than 3:1 and preferably less than 2:1 or even 1.5:1 are advantageous for the purpose of an optimized pre-separation. Preferably, the fluid inlet 24 is arranged such that the inflow direction E is oriented perpendicular to the width direction br, i.e., preferably perpendicular to the direction of the wider expansion.

[0124] Orienting the fluid inlet 24 such that the in-flowing fluid L strikes against a relatively more curved curvature 50 of the wall 30 of the holding section 19 greatly accelerates the fluid L to be filtered, and causes the fluid to then flow tangentially, in particular, helically through the filter element 3. This achieves favorable separation of particles from the fluid L. The fluid inlet 24 may be shielded from the fluid L flowing through the filter element 3 with the aid of a wall 31, which supports the construction of a helical flow. The separated particles are removed from the holding section 19 with the aid of the particle discharge opening 26. The holding section 19 runs in the longitudinal direction LR of the filter element 3, parallel to the outer surface 29 of the filter element 3, so thatas illustrated in FIG. 10a constant distance a is provided between the filter element 3 and the wall 30, perpendicularly to the longitudinal direction LR and circumferentially about the filter element 3.

[0125] FIG. 11 illustrates a partial sectional view of the filter arrangement 1. The fluid L to be filtered flows through the fluid inlet 24 into the holding section 19. Orienting the inflow direction E of the fluid L to be filtered in the direction of the outer surface 29 of the filter element 3 and, in particular, also perpendicular to the longitudinal direction LR causes the fluid L to be filtered to flowas illustrated in FIG. 11 with the aid of an arrow 32helically through the filter element 3 and through the filter body 4 of the filter element 3, in order to continue flowing out of the fluid outlet 25 of the filter holder 2 in the outflow direction A, as the filtered fluid L. When flowing through the filter element 3, particles 33 are separated out from the fluid L to be filtered at the wall 30 of the holding section 19 with the aid of centrifugal force; the particles can then be removed from the holding section 19 via the particle discharge opening 26. The particles 33 can, for example, fall out from the particle discharge opening 26, or be suctioned out therefrom. The oval cross-sectional shape of the holding section 19 results in a favorable particle removal alongside suitability of the system for spaces with a non-circular or rectangular cross-section, in comparison to a circular cross-section.

[0126] As further illustrated in FIG. 11, the maintenance cover 23 has a tubular, and in particular oval tubular inflow protector 48 in which the filter element 3 is at least partially held, preferably such that a flow gap of several millimeters is formed between the filter element and the inflow protector. The inflow protector 48 may be materially integral with the maintenance cover 23, and, in particular, prevents particles that have been pre-separated out by the rotating flow from, for example, still striking against the filter body 4 due to the effects of gravity.

[0127] FIG. 12 illustrates a schematic perspective view of another embodiment of a filter arrangement 1. The embodiment of the filter arrangement 1 according to FIG. 12 differs from the embodiment of the filter arrangement according to FIG. 1 only in that the fluid inlet 24 does not have an oval cross-section, but rather a circular cross-section.

[0128] FIG. 13 illustrates a schematic perspective view of another embodiment of a filter arrangement 1. The embodiment of the filter arrangement 1 according to FIG. 13 differs from the embodiment of the filter arrangement 1 according to FIG. 12 in that the fluid inlet 24 is positioned such that the inflow direction E of the fluid L to be filtered is arranged perpendicular to the height direction hr of the holding section 19, i.e., perpendicular to the direction of the narrower expansion, and not perpendicular to the width direction br thereof.

[0129] FIG. 14 illustrates a schematic perspective view of another embodiment of a filter element 3. FIG. 15 illustrates a sectional view of the filter element 3, and FIG. 16 illustrates a front view of the filter element 3. Reference is made hereinbelow to FIGS. 14 to 16 at the same time.

[0130] The structure of the filter element 3 according to FIGS. 14 to 16 essentially corresponds to the structure of the filter element 3 according to FIG. 6. The filter element 3 has a first end plate 7 and a second end plate 8. A folded filter body 4 is positioned between the end plates 7, 8. The end plates 7, 8 are preferably produced from a molded polyurethane material, especially a foamed one, which encloses the filter body in a sealed and positively-locked manner at the axial ends thereof. The end plates 7, 8 may also, however, be formed from different materials, such as injection-molded thermoplastic polymer, and may be, for example, fused, welded, or adhered to the filter body 4. The filter body 4 surrounds a grid-shaped central tube 5 or winding core. For filtration of the fluid L to be purified, the fluid flows from a pre-filtration side RO of the filter element 3, through the filter medium of the filter body 4, to a post-filtration side RL of the filter element 3. The first end plate 7 includes a receiving opening 11 for receiving a secondary element 13, through which opening the purified fluid also flows out, according to FIG. 7.

[0131] The end plates 7, 8 are preferably oval. The filter body 4 may be partially covered by an inflow protector 12. The inflow protector 12 may be a finely-meshed grid or a foil, which is welded, adhered, or fused to the filter medium. In particular, the inflow protector 12 borders on the first end plate 7. The inflow protector 12 prevents particles 33 contained in the fluid L to be filteredwhich is entering through the fluid inlet 24from striking directly against the filter medium.

[0132] The second end plate 8 is preferably fluid-tight, so that no fluid L is able to reach therethrough from the pre-filtration side RO to the post-filtration side RL of the filter element 3. The second end plate 8 may include, for example, bracing elements 34, only one of which is provided with a reference sign in FIG. 15. The bracing elements may be configured as elastically deformable continuations 8 in the longitudinal direction LR from the end plate 8, the continuations being supportable on the maintenance cover 23 when the maintenance cover is being mounted, and elastically braced by the mounting of the maintenance cover 23. There may be any number of bracing elements 34. The elastically deformable bracing elements 34 make it possible to optimally position the filter element 3 in the holding section 19 of the filter holder 2 with respect to a longitudinal direction LR of the filter element 3. The bracing elements 34 are also used for vibration damping and/or tolerance compensation. The second end plate 8 is preferably materially integral with the bracing elements 34. For example, the second end plate 8 may be formed of a polyurethane foam.

[0133] An elastically deformable sealing device 10 for sealing the filter element 3 off from the holding section 19 is provided at the first end plate 7, and, in particular, at a front side 9 of the first end plate 7 that faces away from the filter body 4. The sealing device 10 is resiliently deformable. Preferably, the first end plate 7 and the sealing device 10 are materially integral. For example, the first end plate 7 and the sealing device 10 may be made from a polyurethane foam. The sealing device 10 completely encircles the first end plate 7. The sealing device 10 is completely inside the cross-section of the filter body 4, in particular, as projected in the longitudinal direction LR.

[0134] The sealing device 10, as illustrated in FIG. 16, includes two first convex curvature sections 35, 36 arranged so as to face one another. The first curvature sections 35, 36 each have a first radius of curvature R35, R36. The radii of curvature R35 and R36 are preferably equal. The radii of curvature R35, R36 have centers of curvature M35, M36. The centers of curvature M35 and M36 lie on a common straight line 37.

[0135] The sealing device 10 additionally has two second convex curvature sections 38, 39 arranged so as to face one another. The first curvature sections 35, 36 and the second curvature sections 38, 39 are connected to one another in a materially integral manner. The second curvature sections 38, 39 have second radii of curvature R38, R39. The second radii of curvature R38, R39 are equal. Centers of curvature M38 and M39 of the radii of curvature R38 and R39 lie on a common straight line 40. The straight line 40 is arranged so as to be perpendicular to the straight line 37. The straight line 37 has a length a.sub.37 and the straight line 40 has a length a.sub.40. Preferably, the straight line 40 divides the straight line 37 in the center, and vice versa. Preferably, the straight line 40 and the straight line 37 intersect at a center point through which a central axis MA of the filter element 3 runs in the longitudinal direction LR, the central axis preferably overlapping with a central axis of the filter holder 2 when the filter element 3 has been installed incorporated the filter holder 2. The sealing device 10 also has an outer contour 41. The outer contour 41 does not run parallel to an outer contour 42 of the first end plate 7. The second radii of curvature R38, R39 are greater than the first radii of curvature R35, R36. The secondary element 13 may have an identically configured sealing device 18.

[0136] In FIG. 16, it is also possible to recognize how the contour of the sealing device 10 runs in comparison to a comparison curve VK. In the concrete illustrated embodiment, as also particularly preferable, the comparison curve VK runs parallel to the outer and/or inner contour of the filter body 4, as well as to the outer and/or inner contour of the open end plate 7, and is further preferably concentric thereto. The comparison curve has, in the center of the second curvature sections 38, 39, the same distance to the outer and inner contour of the filter body 4 and to the outer and inner contour of the open end plate 7 as the inner surface 43. FIG. 16 also shows that the sealing device 10 is more curved in the second curvature section 38 thereof than the comparison curve VK. In other words, in the center thereof, the second curvature section 38 of the sealing device 10 has a smaller (preferably the smallest) distance to the outer contour of the end plate 7 or the filter body 4 than in the region of the transition from the second curvature sections 38, 39 to the first curvature sections 35, 36. As also shown by FIG. 16, a result of the above-described shape is that the second curvature sections 38, 39 of the sealing device 10 protrude in an overlap region into the more-curved curvature sections of the end plate 7 or the filter body 4. In this overlap region UL, the distance of the sealing device 10 or the inner surface 43 from the outer contour of the end plate 7 or the filter body 4 is at a maximum. Thus, the width of the end plate 7 can be used in order to shape the sealing device with the greatest possible curvature, and thus to achieve a favorable sealing effect.

[0137] As illustrated in FIGS. 17 and 18, the sealing device 10 has an oval cylindrical inner surface 43 which forms the sealing surface and rests in a sealed manner against the engagement region 27 of the holding section 19 of the filter holder 2, in particular, against a corresponding sealing contact surface, when the sealing device 10 engages with the engagement region 27. In engagement with the engagement region 27, the sealing device 10 is resiliently deformed, in particular, expanded, in particular, such that the tension of the sealing device 10 against the engagement region 27 is generated exclusively by the resilient deformation. The inner surface 43 then rests in a flat and sealed manner against the engagement region 27. A constant contact pressure of the inner surface 43 against the engagement region 27 is generated around the circumference with the aid of the curvature sections 35, 36, 38, 39. As further illustrated in FIG. 17, the sealing device 10 may have a nearly rectangular shape in cross-section. Furthermore, the sealing device 10 may, as illustrated in FIG. 18, have two sealing lips 44, 45 between which a groove-shaped cavity 46 is arranged. This makes it possible to form a sealing device 10 that is better protected against external influences, due to a filter holder-side tubular web engaging with the groove-shaped cavity such that the inner and/or outer sealing lips can be rested against the tubular web in a sealed manner. The cavity 46 can preferably be axially opened for this purpose.

[0138] As illustrated in detail in FIGS. 19 and 32, the sealing device 10 engages with the engagement region 27 of the holding section 19. Here, the inner surface 43 rests in a flat and sealed manner against the engagement region 27, in particular, against a local, radially outward-pointing, oval cylindrical sealing contact surface 270 (see FIG. 32). The sealing device 10 thus radially inwardly seals the filter element 3 off from the holding section 19. Inwardly is presently understood to mean a direction directed toward the fluid outlet 25.

[0139] FIG. 20 illustrates a schematic perspective view of another embodiment of a filter arrangement 1. FIG. 21 illustrates a schematic partial sectional view of the filter arrangement 1 according to FIG. 20. The filter arrangement 1 includes a filter holder 2, and a filter element 3 that is arranged in the filter holder 2. A fluid inlet 24 of the filter holder 2 is oriented such that an inflow direction E of the fluid L to be filtered is oriented in the direction of a longitudinal direction LR of the filter element 3. The fluid inlet 24 is preferably arranged on a maintenance cover 23 of the filter holder 2. Any number of fluid inlets 24 can be provided.

[0140] As illustrated in FIGS. 21 to 24, each of the fluid inlets 24 has a guide element 47 for redirecting the fluid L. Each of the guide elements 47 has an angle of curvature . The guide elements 47 are suitable for redirecting the in-flowing fluid L to be filtered such that the fluid flows helically through the filter element 3, as illustrated in FIG. 23 with the aid of an arrow 32. The flow against the filter element 3 is then tangential. Particles 33 are hereby separated out at a wall 30 of a holding section 19 of the filter holder 2, and can be discharged out from the filter holder 2 via a particle discharge opening 26 of the filter holder 2.

[0141] The guide elements 47 may be configured as guide blades. Preferably, any number of fluid inlets 24 are provided so as to be distributed over a circumference u (FIG. 25) of the filter holder 2. The angle of curvature a of the guide elements 47 may be varied about the circumference of the filter element 3, in particular, in order to generate an evenly continuous flow. The maintenance cover 23 may further include a tubular inflow protector 48 illustrated in FIG. 24, which is configured materially integrally with the maintenance cover 23. The inflow protector 48 prevents the fluid L to be filtered from directly flowing to the filter element 3, in particular, by separating the fluid inlets 24 from the filter element 3 so as to prevent the particles 33 from directly striking against the filter medium.

[0142] FIG. 25 illustrates a plan view of the filter arrangement 1. As illustrated in FIG. 25, a plurality of fluid inlets 24 may be provided, only two of which are provided with a reference sign in FIG. 25. An opening cross-section of the fluid inlets 24 may vary over the circumference u of the filter holder 2. For example, opening cross-sections of the fluid inlets 24 in regions of greater curvature in the filter element 3 may be larger or smaller than in regions of the filter element 3 in which the filter element has a low curvature.

[0143] FIG. 26 illustrates a schematic perspective view of another embodiment of a filter arrangement 1. FIG. 27 illustrates a rear view of the filter arrangement 1. The filter arrangement 1 includes a filter holder 2. The filter holder 2 according to FIG. 26 differs from the filter holder 2 according to FIG. 1 in having a modified transition section 49.

[0144] As illustrated in FIG. 27, the fluid exit opening 51 of the filter element 3 is oval, and a fluid outlet 25 of the filter holder 2 is circular. The fluid outlet 25 has a circular cross-section facing away from the filter element 3 and has an oval cross-section facing toward the filter element 3. The circular cross-section of the fluid outlet 25 on the side facing away from the filter element 3 preferably has a diameter that is greater than the small diameter of the oval cross-section on the side of the fluid outlet 25 facing toward the filter element 3, and/or that is greater than the diameter of the sealing device 18 in the smaller expansion (in the height direction hr). As FIGS. 28 and 29 illustrate in two schematic sectional views of the filter arrangement 1, a transition between the round fluid outlet 25 and the oval fluid exit opening 51 of the filter element 3 is reached through a curved transition section 49 that is arranged between the fluid outlet 25 and the fluid exit opening 51 of the filter element 3. One advantage of the oval shape of the fluid exit opening 51 of the filter element 3 is the large cross-sectional area thereof. This, in spite of the constriction between the fluid outlet 25 and the fluid exit opening 51 of the filter element 3 illustrated in FIG. 29, results in only a less adverse effect on the pressure loss.

[0145] The filter element 3 may, as illustrated in FIGS. 30 and 31, continue to taper conically on the inside, i.e., a cross-section of a filter medium 4 of the filter element 3 increases going away from a first end plate 7 in the direction of a second end plate 8 of the filter element 3. This makes it possible to achieve an enlarged fluid exit opening 51 of the filter element 3, in comparison to a non-conically tapered filter body 4.

LIST OF REFERENCE SIGNS

[0146] 1 Filter arrangement [0147] 2 Filter holder or filter housing [0148] 3 Filter element [0149] 4 Filter body [0150] 5 Central tube [0151] 6 Thread winding [0152] 7 End plate (in particular, open end plate) [0153] 8 End plate (in particular, closed end plate) [0154] 9 Front side [0155] 10 Sealing device [0156] 11 Receiving opening [0157] 12 Inflow protector [0158] 13 Secondary element [0159] 14 Filter medium of the secondary element [0160] 15 End plate of the secondary element (in particular, open) [0161] 16 End plate of the secondary element (in particular, closed) [0162] 17 Central tube of the secondary element [0163] 18 Sealing device of the secondary element [0164] 19 Holding section of the filter holder [0165] 20 Housing part [0166] 21 Housing part [0167] 22 Fastening means [0168] 23 Maintenance cover [0169] 24 Fluid inlet [0170] 25 Fluid outlet [0171] 26 Particle discharge opening [0172] 27 Engagement region, in particular for the sealing device 10 of the filter element 3 [0173] 28 Engagement region, in particular for the sealing device 18 of the secondary element 13 [0174] 29 Outer surface, in particular of the filter body 4 [0175] 30 Wall, in particular of the holding section 19 [0176] 31 Wall, in particular for guiding flow within the filter holder [0177] 32 Arrow, in particular in the direction of flow through the filter element 3 [0178] 33 Particles [0179] 34 Bracing element [0180] 35 Curvature section, in particular of lesser curvature [0181] 36 Curvature section, in particular of lesser curvature [0182] 37 Straight line [0183] 38 Curvature section, in particular of greater curvature [0184] 39 Curvature section, in particular of greater curvature [0185] 40 Straight line, in particular center line [0186] 41 Outer contour, in particular of the sealing device 10 [0187] 42 Outer contour, in particular of the end plate 7 and/or 8 [0188] 43 Inner surface, in particular of the sealing device 10, in particular, sealing surface [0189] 44 Sealing lip, in particular having a radially inward sealing edge or sealing surface [0190] 45 Sealing lip, in particular having radially outward or inward sealing edge or sealing surface [0191] 46 Cavity, in particular groove between the sealing lips 44, 45 [0192] 47 Guide element [0193] 48 Inflow protector, in particular on the maintenance cover 23 [0194] 49 Transition section, in particular at the fluid inlet 24 [0195] 50 Curvature [0196] 51 Fluid exit opening, in particular through the end plate 15 of the secondary element 13 [0197] 270 Sealing contact surface of the engagement region 27 [0198] 280 Sealing contact surface of the engagement region 28 [0199] a Distance [0200] A Outflow direction [0201] a.sub.37 Length [0202] a.sub.40 Length [0203] b Width [0204] br Width direction [0205] E Inflow direction [0206] h Height [0207] hr Height direction [0208] L Fluid [0209] LR Longitudinal direction [0210] MA Central axis [0211] M35 Center of curvature [0212] M36 Center of curvature [0213] M38 Center of curvature [0214] M39 Center of curvature [0215] RE Post-filtration side [0216] RO Pre-filtration side [0217] R35 Radius of curvature [0218] R36 Radius of curvature [0219] R38 Radius of curvature [0220] R39 Radius of curvature [0221] u Circumference [0222] UL Overlap region [0223] VK Comparison curve [0224] Angle of curvature