Abstract
A filter element (1) has an inner body (12) and an outer body (11). One casing body (12) has a cross section deviating from circularity. Body contact surfaces (20, 21) face one another for the contact of essentially all filter folds (18a-18f, 18.sub.I-18.sub.III) of a pleated filter web (10). The filter folds (18a-18f, 18.sub.I-18.sub.III), in terms of fold height (h), are divided into individual groups (I, II) each having several filter folds (18.sub.I-18.sub.II) of a common fold height (h.sub.max, h.sub.min) alongside one another in sections. Between two adjacent filter folds (18a-18f, 18.sub.I-18.sub.III) of different groups (I, II) filter folds are arranged (18b-18e; 18m) of at least one third group (III). The filter folds (18b-18e, 18m) of the third group (III), in the manner of step formation, have a common fold height (h.sub.D) different from the respective fold height (h.sub.max, h.sub.min) of the filter folds (18.sub.I-18.sub.II) of the two adjacent neighboring groups (I, II), and/or, in the manner of curve formation, have different fold heights, establishing a transition between the fold heights (h.sub.max, h.sub.min) of the two adjacent groups (I, II).
Claims
1. A filter element, comprising: at least one inner jacket body and at least one outer jacket body with inner and outer contact faces, respectively, at least one of said jacket bodies deviating from a circular shape and the other of said jacket bodies substantially conforming to a circular shape; and a pleated filter web consisting essentially of filter folds divided at least first, second and third individual groups of a plurality of said filter folds arranged alongside each other in sections, said filter folds contacting the respective contact faces, each of said filter folds having a fold height, each of said filter folds in each of said first and second groups having a common or equal fold height in the respective individual group, said filter folds of said third individual group being arranged between two adjacent filter folds of said first and second individual groups, each of said filter folds of said third individual group in a step formation having a common or equal fold height different from the respective fold heights of the filter folds of adjacent adjoining first and second individual groups.
.[.2. A filter element according to claim 1 wherein the fold height of each of said filter folds of said third individual group produces a transition between the fold heights of the adjacent adjoining first and second individual groups..].
.[.3. A filter element according to claim 2 wherein said transition has a wave or sine shape..].
4. A filter element according to claim 1 wherein adjacently juxtaposed filter folds of said first individual group each have a first fold height; adjacently juxtaposed filter folds of said second individual group each have a second fold height and are arranged in an alternating sequence with said first individual group along said filter web, said first and second fold heights being different; and between the adjacently juxtaposed filter folds of said first and second individual groups, adjacently juxtaposed filter folds of said third individual groups are arranged.
5. A filter element according to claim 4 wherein said third fold height is an average of said first and second fold heights.
6. A filter element according to claim 1 wherein numbers of the filter folds of each of said first and third individual groups are equal.
7. A filter element according to claim 1 wherein the filter folds follow a periodic course of first, second and third individual groups along said filter web, with each period having 15 to 20 filter folds.
8. A filter element according to claim 1 wherein said inner jacket body has a cross-sectional shape of a convex polygon.
9. A filter element according to claim 8 wherein said convex polygon is a Reuleaux polygon.
10. A filter element according to claim 1 wherein said outer jacket body has a cross-sectional shape of a convex polygon.
11. A filter element according to claim 10 wherein said convex polygon is a Reuleaux polygon.
12. A filter element according to claim 1 wherein each filter fold has a cross-sectional configuration of at least one of a zigzag, a wave and a sickle.
13. A filter element according to claim 1 wherein said filter web is closed and has filter web ends connected in a connecting region.
14. A filter element according to claim 1 wherein said outer jacket body has a circular shape in cross section; and said inner jacket body has a non-circular shape in cross section.
15. A filter element according to claim 1 wherein said filter folds have inner and outer peaks substantially evenly spaced on said inner and outer contact faces, respectively.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Referring to the drawings which form a part of this disclosure and which are schematic and not drawn to scale:
(2) FIG. 1a is a top view of a conventional filter element;
(3) FIG. 1b is a side elevational view of a disassembled conventional filter web;
(4) FIG. 2a is a top plan view of a filter element according to a first exemplary embodiment of the invention;
(5) FIG. 2b is a side elevational view of the disassembled filter web of FIG. 2a;
(6) FIG. 3a is a side elevational view of a filter web of a filter element in the disassembled state according to a second exemplary embodiment of the invention;
(7) FIG. 3b is a perspective view of the filter web of FIG. 3a;
(8) FIG. 4 is a side elevational view of a filter web of a filter element according to a third exemplary embodiment of the invention;
(9) FIG. 5a is a top plan view of the filter housing shown in the partially opened state with a filter element according to the first exemplary embodiment of the invention arranged in the filter housing;
(10) FIG. 5b is a perspective view of the filter housing of FIG. 4a partially cut open; and
(11) FIG. 6a-FIG. 6d are each a schematic drawing of a Reuleaux polygon.
DETAILED DESCRIPTION OF THE INVENTION
(12) FIG. 1a shows a conventional filter element 1 with a folded filter web 10, formed into a round tubular body and laid around a fluid permeable inner jacket body 12 designed as a support tube. Lying on the outside of web 10 is an outer jacket body 11, indicated by a dashed line. Each of the two jacket bodies 11, 12 has a cross section in the shape of a circle. The circular cross-sectional shapes of the outer and inner jacket bodies 11, 12 have a common center point M. In other words, the inner jacket body 12 and the outer jacket body 11 are arranged concentrically to each other. During the filtration operation, the filter element 1 or more specifically its filter folds 18a-18c are traversed by flow from the outside to the inside, that is, in the direction of the center point M. A connecting region 14 of the filter web 10 is formed on the filter web ends 16a, 16b, which form the closure of the tubular body. The connecting region 14 can be made by welding or gluing the longitudinal edges arranged alongside each other at the ends 16a, 16b of the filter web.
(13) In the pleated filter web 10, the filter folds 18a-18c have substantially the same shape, have in each instance the same filter height h and rest in each instance against both an outer contact face 20 defined by the outer jacket body 11 and against an inner contact face 21 defined by an inner jacket body 12. The filter height h of the filter folds 18a-18c corresponds to at least the radial distance between the inner contact face 21 and the outer contact face 20 or rather between the inner jacket body 12 and the outer jacket body 11.
(14) FIG. 1b is a side elevational view of a filter web 10 of an additional conventional filter element (not illustrated). The filter folds 18.sub.I, 18.sub.II arranged alongside each other along the filter web 10 are divided into two groups I, II. The filter folds 18.sub.I of the first group I have a first fold height h.sub.1 and are arranged in the middle section 26′ of the filter web 10 such that they are arranged alongside each other. The filter folds 18.sub.II of the second group II have a second fold height h.sub.2 and are arranged in the left section 26 and in the right section 26″ of the filter web 10 such that they are arranged alongside each other in each instance. The second fold height h.sub.2 is smaller than the first fold height h.sub.1. A sharp transition, between the filter folds 18.sub.I, 18.sub.II arranged to be adjacent to each other at the respective transitions, is formed at the transition from the left section 26 to the middle section 26′ and from the middle section 26′ to the right section 26″. The left section 26 and/or the right section 26″ of the filter web 10 can be followed by additional filter folds 18.sub.I, 18.sub.II of the two groups I, II with a fold height that changes in the manner of a step between the first fold height h.sub.1 and the second fold height h.sub.2.
(15) FIGS. 2a and 2b show a filter element 1 according to the invention, comprising a filter web 10 with filter folds 18a-18f, 18.sub.I-18.sub.III defining a circular cross-sectional shape of the outer jacket body 11 and a cross-sectional shape of the inner jacket body 12 that deviates from the shape of a circle, because of the different filter heights h.sub.min, h.sub.max. The filter folds 18a-18f, 18.sub.I-18.sub.III are arranged in direct succession along a direction of extension 24 of the filter web 10 and have a constant outer fold distance b. The inner fold distance along the inner jacket body 12 varies between the minimum inner fold distance a′ and a maximum inner fold distance a. The filter folds 18f, 18.sub.I of the first group I with a maximum fold height h.sub.max exhibit the maximum inner fold distance a. The filter folds 18a, 18.sub.II of the second group II with a minimum fold height h.sub.min, exhibit the minimum inner fold distance a′. All of the filter peaks defined by the filter folds 18a-18f, 18.sub.I-18.sub.III protrude internally and externally and rest against a contact face 20, 21 on the respective jacket body 11, 12, with the outer contact face 20 having a cylindrical shape, and the inner contact face 21 having a shape that deviates from the cylindrical shape.
(16) The filter folds 18a-18f, 18.sub.I-18.sub.III are arranged and configured periodically with a period f along the direction of extension 24 of the filter web 10. In the present example, the period f comprises 17 filter folds. In a first section 26a, comprising four filter folds 18b-18e of the third group III, the fold height decreases continuously from a maximum value h.sub.max of the first group I or more specifically the filter folds 18f, 18.sub.I corresponding to the fold height h.sub.max to the minimum value h.sub.min of the second group II or more specifically the fold height h.sub.min of the corresponding filter folds 18a, 18.sub.II. The adjoining second section 26.sub.min has five filter folds 18a, 18.sub.II of the second group II with a minimum fold height h.sub.min. This second section is followed by a third section 26b with four filter folds 18.sub.III of the third group III having a filter height that increases continuously from a minimum value h.sub.min to a maximum value h.sub.max following a linear course. The maximum value h.sub.max of the fold height is exhibited in turn by the four filter folds 18.sub.I of the first group I in a fourth section 26.sub.max.
(17) The illustrated and described parameters, the filter height h having a minimum value h.sub.min and a maximum value h.sub.max, the period f, the minimum inner fold distance a′, the maximum inner fold distance a as well as the outer fold distance b and the total number of filter folds 18a-18f, 18.sub.I-18.sub.III can be variably adjusted and optimized as a function of the respective application of the filter element 1 and to match the installation space. FIG. 2a shows very clearly that the filter element 1 can be inserted into a conventional cylindrical installation space, because the design according to the invention is visible only on the inner jacket body 12, which is formed to match.
(18) FIGS. 3a and 3b show an additional filter web 10, which is folded in the form of pleats, with the filter web having filter folds 18a-18f, which vary between a minimum filter height h.sub.min and a maximum filter height h.sub.max. These filter folds are arranged to lie closely alongside each other and are divided into three groups I, II, III. In the direction of extension 24 from the first end 16a of the filter web to the second end 16b of the filter web, the filter height of the filter folds 18.sub.I-18.sub.III varies with the period f comprising four filter folds 18.sub.III of the third group III with a decreasing fold height in the first section 26a, five filter folds 18.sub.II of the second group II with a minimum fold height h.sub.min in the second section 26.sub.min, four filter folds 18.sub.III of the third group III with an increasing fold height in the third section 26b, and four filter folds 18.sub.I of the first group I with a maximum filter height h.sub.max in the fourth section 26.sub.max. It is very clear from FIG. 3b that in order to avoid sharp transitions, the transition from the minimum fold height h.sub.min to the maximum fold height h.sub.max is designed so as to be “soft,” in other words, in a flowing or continuous manner with a slight decrease or increase.
(19) The aforementioned exemplary embodiments involve only preferred alternative solutions that can also be modified, in particular, with respect to the number of folds and the fold height. In addition to the geometries in the form of a zigzag or sickle shape, etc., so-called loop folds can also be used in the fold geometry. Moreover, the fold geometry can also be freely specified and designed as a function of the intended application.
(20) FIG. 4 is a side view of an additional filter web of an additional filter surface element, which is not shown in its entirety. The drawing from FIG. 4 corresponds for the most part to the drawing from FIG. 2b and differs from FIG. 2b in that the filter folds 18b-18e, 18.sub.III of the third group III have both the same third fold height h.sub.D as well as altogether this fold height h.sub.D in the respective section 26a, 26b of the filter web 10. It is very clear from FIG. 4 that the third fold height h.sub.D of the first filter folds 18b-18e, 18.sub.III assigned to the third group III represents the average value of the first fold height h.sub.max of the filter folds 18f, 18.sub.I assigned to the first group I and the second filter fold height h.sub.min of the filter folds 18a, 18.sub.II assigned to the second group II and that the number of folds in each of group I and group III is the same, specifically four.
(21) However, it is also conceivable that in an embodiment which is not shown, the filter folds 18b-18e in the left section 26a have a fold height that differs from the fold height of the filter folds 18.sub.III of the third group III in the right section 26b. Furthermore, it is possible to provide a filter web 10 with a transition (shown in FIG. 2b) between the first fold height h.sub.max and the second fold height h.sub.min that is combined with an arrangement of the filter folds 18b-18e, 18.sub.III in the respective section 26a, 26b such that this arrangement of those filter folds is in the manner of steps in sections as shown in FIG. 4. In addition, the filter folds 18b-18f, 18.sub.III of the third group III can fall below or exceed the first fold height h.sub.max and/or the second fold height h.sub.min in the respective section 26a, 26.
(22) FIGS. 5a and 5b show a filter housing 30, into which the filter element 1 with the filter web 10 according to FIGS. 2a and 2b is inserted. Connected to a head part 32 of the filter housing 30 is a cylindrical installation space 34, into which the filter element 1 with the tubular outer jacket body 11 is inserted. Connected to the inner jacket body 12 (not illustrated) is a hold-down device 36, designed correspondingly in the shape of a Reuleaux polygon, on the head side. The hold-down device 36 is traversed by the flow of a hydraulic medium and is introduced in a positive locking manner into the inner contour of the corresponding element holder. The edge of the hold-down device 36 absorbs the axial forces by the protrusions in the element holder. In the illustrated example, the hold-down device 36 is designed for a flow direction from the inside to the outside, as shown with the arrows 50.sub.E, 50.sub.F, 50. The head part 32 has holes 38a-38d as the handling and/or fastening aid as well as an inlet 40 and an outlet 42 for the fluid that is to be cleaned or that has been cleaned. An additional outlet 46 for a return line 50.sub.R is arranged on the end of the filter housing 30 that is situated opposite the head part 32. This additional outlet is also provided with a back pressure valve 48. The filter element 1 can be installed, like a conventional filter part, in the filter housing 30, but when such a filter is running, a larger effective filter surface area with improved stability properties is made available.
(23) FIGS. 6a-6d show Reuleaux polygons or more specifically orbiform curves, of which the contour line is marked with the reference numeral 2. In general, a Reuleaux polygon or a convex polygon has an odd number of corners and has nothing but arcs having the same radius. Since the center point of each arc has to lie in the exactly opposite corner 5, 7, 9 of the polygon, the Reuleaux polygon is based on a star polygon 3 (not necessarily regular) with sides of equal length. A Reuleaux triangle, shown in FIG. 6a, is made of an equilateral triangle 3 by replacing its edges with arcs with the radius equal to the edge length and with the center point in the opposite corner point. The characteristic property of a Reuleaux polygon is that it has a constant width b, independently of the direction in which it is measured.
(24) The orbiform curve shown in FIG. 6d is based on an equilateral triangle 3 with corner points 5, 7, and 9, with each corner point 5, 7, 9 being a center point of a circle with a radius r.sub.1 and an arc with the radius r.sub.2. These two radii are shown only starting from the corner point 5 in FIG. 6d. The size of the radius r.sub.2 is chosen in proportion to the radius r.sub.1 in such a way that the corresponding arc is tangential to the circle with the radius r.sub.1 and, in this way, produces the closed contour line, designated as 1 in FIG. 6d. The diameter d.sub.1 of the orbiform curve formed in this way corresponds to the sum of the radii r.sub.1 and r.sub.2. The periphery of the orbiform curve, that is, the length of the contour line 2, is as large as the periphery of a circle with the diameter d.sub.1.
(25) While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.
