Filter element and filter device with the filter element

Abstract

Filter element for separating particles from a fluid, in particular from a hydraulic fluid, with a circumferential sequence of folds, wherein in a cross-sectional plane an inner cross-section (108) deviating from a circular shape is defined via fold valleys and an outer cross-section (110) of the filter element (6; 106) deviating from a circular shape is defined via fold crests, characterized in that the cross sections (108, 110) have a constant distance from one another, wherein the cross sections (108, 110) are drop-shaped at least in sections.

Description

[0001] The invention relates to a filter element for separating solid particles from a fluid according to the preamble of claim 1, as well as a filter device with this filter element according to claim 5.

[0002] The document DE 20 2009 000 969 U1 shows a pleated filter element, i.e., one with folds. The filter element is designed in a closed ring or cuff shape. It extends essentially cylindrically in the direction of the pleat crests and troughs, with the inner pleat valleys defining an inner contour and the outer pleat crests defining an outer contour of the cylinder. Numerous embodiments are shown in which the inner contour, the outer contour, or both deviate from a circular cross-section. For example, angular, wavy, oval, and other inner and outer contours are combined in a variety of ways.In this way, the filter element can be individually adapted to the inflow conditions and the particle load of the inflowing fluid, whereby the particle load of the filter element can be optimized compared to a filter element with a circular cylindrical shape and thus the service life of the filter element can be extended.

[0003] A disadvantage of this solution, for example, is that precise adherence to the desired inner and outer contours depends on precise pleating, particularly on the correct adjustment and modification of the respective pleat height depending on the circumferential length of the filter element. This requires considerable manufacturing effort.

[0004] US 2015 / 265949 A1 discloses a filter unit with an outer, pleated filter and an inner filter. The outer, pleated filter has an oval shape.

[0005] DE 10 2015 005 101 A1 shows a filter system with a filter medium arranged flat on a support tube.

[0006] US 2015 / 151233 A1 shows another filter unit with an outer, pleated filter element arranged to enclose an inner support structure. The outer, pleated filter element can be round, non-round, oval, rectangular, or elliptical.

[0007] DE 10 2011 011 595 A1 shows a tubular filter medium with an annular cross-section that encloses the interior of a filter element with its inner wall. The inner wall, for example, runs in the form of two convex arches, between which two concave arches are arranged. Thus, convex arches alternate with concave arches. In the area of ​​the concave arches, the opposing inner walls approach each other, resulting in a constriction of the filter element interior. The filter medium can also have straight sections.

[0008] In contrast, the invention is based on the object of creating a filter element that is easier to manufacture while still providing optimized airflow and particle load. A further object is to provide a filter with such a filter element.

[0009] The first object is achieved by a filter element having the features of claim 1, the second object by a filter having the features of claim 6.

[0010] Advantageous further developments of the filter element and of the filter are described in the dependent claims.

[0011] A filter element has a circumferential sequence of pleats, with an inner cross-section deviating from a circular shape being defined in a cross-sectional plane of the filter element by pleat valleys and an outer cross-section deviating from a circular shape being defined by pleat crests. According to the invention, the inner and outer cross-sections are at a substantially constant distance from one another, i.e., they are substantially parallel to one another.

[0012] In this way, the filter element's individual shape, which deviates from the circular shape, is well adapted to the specific particle load and flow situation. At the same time, the filter element can be manufactured with consistent pleats, especially consistent pleat height. This simplifies production, as the pleats no longer influence the desired cross-sectional shape. This solution optimally combines the filter element's form, function, effectiveness, and manufacturing effort.

[0013] In a further development, the cross-sections are oval, teardrop-shaped, or linear, at least in sections. Areas of lesser curvature on the filter element, which thus have a larger surface area relative to the angular interval covered by the filter element, allow for better airflow around the filter element. Both the oval and teardrop shapes allow for optimal airflow around the filter element.

[0014] Alternatively or additionally, the cross-sections are formed at least in sections by a free-form curve and thus adapted particularly precisely to the individual particle load and the flow situation.

[0015] A filter device according to the invention has a filter housing in which a filter element according to the preceding description is accommodated.

[0016] In a further development, the filter housing has an inlet channel through which the fluid to be filtered flows to the filter element, in particular transversely to a longitudinal axis of the filter element. The inlet channel opens with an inlet opening into an inlet chamber delimited by the filter element and the filter housing. A filter element section, which has a comparatively small curvature compared to the rest of the filter element, is arranged away from the inlet opening, in particular substantially opposite the inlet opening. In contrast to filter elements with circular cross-sections, more filter material and thus more filter surface area is arranged where there is less fluid to be filtered, i.e. away from or approximately opposite the inlet opening. The increased filter surface area has the advantage that the filter element has a longer service life. The replacement intervals are therefore extended.This means that more dirt and more particles can be separated from the fluid to be filtered per filter element.

[0017] In a further development, the inlet chamber extends, at least in sections, as an annular space between the filter element and the filter housing. The annular space is wider in an area close to the inlet chamber opening than in an area facing away from the inlet, which extends away from the inlet chamber opening. Since the most contaminated fluid enters the filter element directly at the inlet chamber opening, the largest free flow cross-section between the filter element and the filter housing is required there. Due to the wider annular space there and the resulting larger flow cross-section, the contaminated fluid can then flow easily, with low flow resistance and pressure loss, into the more distant, outer areas of the filter element, where other sections are available for filtration.This evens out and improves the flow to the filter element, which in turn protects the filter element material, contributing to a longer service life and more efficient filtration. This brings with it a cost advantage. The reduced pressure loss saves energy.

[0018] In a further development, the filter element is placed, directly or indirectly, on a connection piece fixed to the housing, which is shaped to fit the inner contour.

[0019] In order to further improve the flow to the filter element, the filter element is accommodated eccentrically in the filter housing in a further development.

[0020] An embodiment of a filter according to the invention and two embodiments of filter elements according to the invention are shown in the drawings. The invention will now be explained in more detail with reference to the figures in these drawings. They show: Fig. 1 an embodiment of a filter with an inserted filter element in a longitudinal section. Fig. 2 a cross section of the filter element according to the invention Fig. 1, and Fig. 3 a cross section of a filter element according to the invention according to a second embodiment.

[0021] Fig. Figure 1 shows a filter 1 designed as a hydraulic line filter according to one exemplary embodiment, in a full section along its longitudinal axis. Such filters 1 are arranged, for example, directly downstream of a hydraulic pump and separate particles or contaminants from the main pressure medium flow of the hydraulic pump. However, the filter 1 can also be arranged, for example, in a hydraulic subcircuit upstream of a sensitive hydraulic device.

[0022] According to Fig. 1, a filter 1 has a partially pot-shaped filter housing 2 (housing cover not shown) with a filter housing base 4. The filter housing 2 accommodates a hollow cylindrical filter element 6 with an oval inner cross-section 8 and a parallel, oval outer cross-section 10.

[0023] A representative cross-section of the filter element 6 according to Fig. 1 shows Fig. 2. Fold valleys form the inner cross-section 8 and fold crests form the outer cross-section 10.

[0024] The cross sections 8, 10 are each formed by connecting curves of the pleat valleys and crests. The same applies analogously to the filter element 106 according to Fig. 3 with respect to the inner cross-section 108 and the outer cross-section 110.

[0025] Through an inlet channel 12 formed in the filter housing 2, the Fig. 1 during operation, pressure medium flows via an inlet chamber opening 14 into an annular inlet chamber 16, towards an outer side of the filter element 6, through this, into an inner outlet chamber 18, and from there through an outlet channel 20 passing through the filter housing base 4.

[0026] Alternatively, with a different housing design, the flow can be from the front side of the filter element.

[0027] In the embodiment shown, the filter element 6 is flowed approximately radially on the side of the inlet chamber opening 14.

[0028] The general task of such filters is to supply the filter element 6 with the fluid to be filtered as evenly as possible. This is achieved here by providing a correspondingly large flow cross-section for the initially large fluid volume flow at the inlet chamber opening 14. For this purpose, the inlet chamber 16 has a greater width, measured in the cross-sectional plane, in the area of ​​the inlet chamber opening 14 than in a region 13 facing away from the inlet channel 12, which extends away from the inlet chamber opening 14 and in particular opposite the inlet chamber opening 14.

[0029] The fluid flows around the filter element 6, starting from the inlet chamber opening 14, towards the area 13 facing away from the inlet channel 12. On the way, fluid increasingly passes through the filter element 6 into the outlet chamber 18 and is thus cleaned. The fluid volume flow in the inlet chamber 16 thus decreases steadily towards the area 13 facing away from the inlet channel 12. In the area 13 facing away from the inlet channel 12, the gap between the filter element 6 and the filter housing 2 can thus be made smaller, which Fig. 1 also shows. This is accompanied by the fact that in the area 13 facing away from the inlet channel 12, more filter area is available, relative to the fluid volume flow there.

[0030] The contaminated fluid can be filtered off in particular by the oval shape, or even better by the drop shape according to the invention Fig.3, flow well around the filter element, penetrate into the filter element 6 there and penetrate through the “enlarged” filter surface in the area 13 facing away from the inlet channel 12 inwards into the outlet space 18 and thus undergoes cleaning.

[0031] The shapes of the filter elements 6 and 106 shown represent an optimal solution even for existing filters and can also be used there.

[0032] Compared to conventional, circular filter elements, more filter material is available relative to the fluid volume flow precisely where the flow rate is reduced (in the area 13 facing away from the inlet channel 12, and especially opposite the inlet chamber opening 14). Such an increased filter surface area has the advantage of a longer filter element service life and a longer filter replacement interval. This allows more dirt to be removed from the fluid to be filtered per filter element. List of reference symbols 1 filter 2 filter housings 4 Filter housing base 6; 106 filter element 8; 108 internal cross-section 10; 110 external cross-section 12 inlet channel 13 Area facing away from the inlet channel 14 Inlet chamber mouth 16 Inlet chamber 18 Drainage room 20 drainage channel

Claims

[1] Filter element for separating particles from a fluid, in particular from a hydraulic fluid, with a circumferential sequence of folds, wherein in a cross-sectional plane an inner cross-section (108) which deviates from a circular shape is defined over fold troughs and an outer cross-section (110) of the filter element (6; 106) which deviates from a circular shape is defined over fold crests, characterized by , that the cross-sections (108, 110) have a constant distance from each other, wherein the cross-sections (108, 110) are at least partially teardrop-shaped. [2] Filter element according to claim 1, wherein the cross-sections (8, 10) are at least partially oval. [3] Filter element according to one of claims 1 to 2, wherein the cross-sections are at least sectionally linear. [4] Filter element according to one of the preceding claims, wherein the cross-sections are formed at least section by a freeform curve. [5] Filter device comprising a filter housing (2) in which a filter element (6; 106) is included according to one of the preceding claims. [6] Filter device according to claim 5, wherein the filter housing (2) has an inlet channel (12) which opens with an inlet opening (14) into an inlet space (13, 16) bounded by the filter element (6; 106) and by the filter housing (2), wherein a filter element section which has a comparatively small curvature in the cross-sectional plane compared to the rest of the filter element (6, 106) is arranged further away, in particular opposite, the inlet opening (14), so that more filter material and thus more filter area is arranged further away from or opposite the inlet opening (14). [7] Filter device according to claim 5 or 6, wherein the inlet space (13, 16) extends at least sectionally as an annular space between the filter element (6; 106) and the filter housing (2), which is wider in an area near the inlet space opening (14) than in an area (13) facing away from or farther from the inlet channel (12). [8] Filter device according to one of claims 5 to 7, wherein the filter element is placed directly or indirectly on a housing-fixed connection nozzle which is shaped to fit the inner cross-section. [9] Filter device according to one of claims 5 to 8, wherein the filter element is eccentrically mounted in the filter housing.

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