Varying filter media thickness for improved flow and

Abstract

A thicker portion and a thinner portion of the filter media sheet are provided in the filter element. The filter element includes a ring of filter media disposed about a central support tube. The filter media includes a pleat of the media including an inner pleat end adjacent the tube and an outer pleat end spaced radially outward from the tube. The thickness of the layer varies between the ends such that a portion of the media is thinner at the ends of the inner pleats than at the ends of the outer pleats.

Description

Technical Field

[0001] The present invention generally relates to a pleated filter media sheet arrangement structure, such as a pleated filter media sheet arrangement structure that can be incorporated into a filter media ring supported by an inner support tube. Background Art

[0002] Filter media is typically pleated to increase the surface area to improve filtration performance in a compact space. In many applications, the media is wrapped around a perforated central tube to form an annular shape. The central tube provides structure to the assembly during use when a pressure differential across the filter media is generated by fluid flow. The amount of filter media available in such an assembly is limited to the total pleat end width at the inner diameter around the central tube.

[0003] In the art, suggestions for disposing beads and / or forming protrusions have been made in different pleated filter media arrangements, for example, as can be seen in the following patent disclosures: DE102015006355A1, US10632412B2, WO02055179A1, US20140202123A1, and DE4345130C1 (see also the article by Li et al., Research on the Filtration Performance of Pleated Filter with Rectangular and Triangular Structures Through Developed Cfd Code, published on June 3, 2022, https: / / papers.ssm.com / sol3 / papers.cfm?abstract id = 4126929 )

[0004] These prior attempts either limit or reduce the filtration capacity (e.g., due to adhesive beads clogging the media) and / or limit the amount of media, or add additional complexity.

[0005] The present disclosure and the embodiments herein provide different and novel solutions for increasing the flow area, particularly in embodiments where the media is wrapped into an annular shape. These and other advantages of the present invention, as well as additional inventive features, will become apparent from the description of the present invention provided herein. Summary of the Invention

[0006] The present invention reduces the thickness of the filter media at the inner diameter pleat ends, thereby allowing for more available filter media surface area on the filter, which improves performance.

[0007] This technique has not been used in the filtration industry to date. Pleated annular assemblies have been used in the industry for decades. Typically, the media layer has a uniform thickness, which is then folded to form pleats.

[0008] The pleats are mainly created using rotating rollers, the rollers being provided with protruding scoring bars that project from the rollers creating the folded pleats. The height of the pleats is directly related to the spacing of the scoring bars around the rollers. According to one embodiment, the base roller diameter increases from one scoring bar to the next such that the medium is compressed in a progressive pressure from a nominal pressure at one score to a higher pressure at the next score. According to another embodiment using a flat press (see, for example, U.S. Patent No. 11,235,270, the entire content of which is incorporated herein by reference), when the medium advances between the die plates, the reciprocating die plates shape the medium with each up-and-down reciprocating movement. This allows for variable base medium compression with less tool complexity.

[0009] Aspects of the present invention relate to a filter element that includes a ring of filter medium disposed around a central support tube. The filter medium includes a pleated layer of the medium that includes an inner pleat end adjacent the tube and an outer pleat end radially outwardly spaced from the tube. The thickness of the layer varies between the ends such that a portion of the medium is thinner at the inner pleat end than at the outer pleat end.

[0010] Another aspect of the present invention relates to a sheet of filter medium that includes a pleated layer of the filter medium that includes pleat ends at opposite first and second flow faces. The pleated layer includes a thinner portion of the filter medium extending from the pleat end at the first flow face toward the second flow face and a thicker portion of the filter medium extending from the pleat end at the second flow face toward the first flow face, the thicker portion being thicker than the thinner portion.

[0011] In the above aspect of the sheet of filter medium, the sheet of filter medium can be used in a filter element, wherein the sheet of filter medium is wound into a ring and defines a central cavity, the radially inner circumference of the ring being provided by the pleat end at the first flow face (i.e., the inner pleat end), and the radially outer circumference of the ring being provided by the pleat end at the second flow face (i.e., the outer pleat end) radially outwardly spaced from the inner radial circumference.

[0012] Yet another aspect of the present invention relates to a method of creating a filter medium pack that includes: creating a thicker portion and a thinner portion of a sheet of filter medium, the thicker portion being thicker than the thinner portion; folding the sheet of filter medium at the thinner portion; folding the sheet of filter medium at the thicker portion, thereby creating a pleat between the folds at the thinner portion and the thicker portion; and winding the filter medium pack into an annular shape with the thinner portion at the inner radial circumference and the thicker portion at the outer radial circumference.

[0013] Any of the above aspects can be used alone or in combination with one or more features in combination with each feature in the following paragraphs.

[0014] The features are: Pleat indentations may be provided at the inner pleat ends and at the outer pleat ends. The pleat indentations adjacent to the thinner part of the medium are adjacent to the inner pleat ends, compared with the pleat indentations adjacent to the thicker part of the medium and adjacent to the outer pleat ends. Preferably, except for the pleat indentations, the thinner part may have a minimum thickness that is 20% to 90% thinner than the maximum thickness of the thicker part.

[0015] The features are: The filter medium may have a thickness that gradually increases as the filter medium extends radially outward from the inner pleat ends to the outer pleat ends. Optionally, the gradually increasing thickness may also vary continuously as the filter medium extends radially outward.

[0016] The features are: The thickness of the filter medium may vary in a stepped manner as the filter medium extends radially outward from the inner pleat ends to the outer pleat ends.

[0017] The features are: Preferably, at least one radially extending section having a constant thickness (e.g., an unchanged thickness) is provided in the thicker part as the thicker part extends radially inward from the outer pleat ends; and optionally, the thinner part may have a radially extending section of constant thickness.

[0018] The features are: A thicker part of the medium is provided, which is thicker than the thinner part, and in the thinner part, the thinner part may be 20% to 90% thinner than the maximum thickness of the thicker part.

[0019] The features are: The filter medium may include: a pleat depth extending between the inner pleat ends and the outer pleat ends between 0.9 cm and 7.7 cm; a maximum caliper thickness between 0.2 mm and 5.1 mm.

[0020] The features are: A central support tube may be used, and the central support tube may have an outer diameter between 1 cm and 40 cm.

[0021] The features are: The thickness of the thinner part may remain substantially constant across the span of the filter medium ring, and the span is parallel to the pleat ends.

[0022] The features are: The filter medium may have no protrusions and has opposite, substantially flat surfaces in the middle of the pleat ends.

[0023] The features are: The thinner part may extend between 5% and 50% of the pleat depth of the pleat layer, and preferably between 10% and 30% of the pleat depth of the pleat layer. Preferably, the thinner part is only provided in the inner half of the pleat depth.

[0024] The features are that the thinner part forms a space at the inner peripheral edge of the ring to provide a larger flow gap between adjacent inner pleat ends, and / or due to more pleats, more filter medium is used in the ring (compared with the same layout structure except for the thinner part used - see for example Figure 2 and Figure 3Comparison).

[0025] The feature is that as the thinner portion extends radially outward perpendicular to the end of the inner fold, the thinner portion can merge into the thicker portion.

[0026] The feature is that the thinner portion has a minimum thickness that is 20% to 90% thinner than the maximum thickness of the thicker portion. Preferably, the pleat crease is provided at the end of the pleat, and the thinner and thicker portions of the filter medium extend from the corresponding pleat crease.

[0027] The feature is that as the filter medium extends vertically from the end of the pleat at the first flow surface to the end of the pleat at the second flow surface, the filter medium can have a gradually increasing thickness.

[0028] The feature is that as the filter medium extends vertically from the end of the pleat at the first flow surface to the end of the pleat at the second flow surface, the thickness of the filter medium can vary in a stepped manner.

[0029] The feature is that as the filter medium extends vertically from the end of the pleat at the first flow surface to the end of the pleat at the second flow surface, the filter medium can have a gradually increasing conical thickness over at least a portion of the pleat depth.

[0030] The feature is that a method for manufacturing a filter pack and / or a filter element (i.e., a production method) can score a filter medium pack at a first score line in the middle of the thinner portion and a second score line in the middle of the thicker portion, and promote folding along the first and second score lines.

[0031] The feature is that the production method can convey a filter medium sheet along a forward path to a plate press or mating rolls; compress the filter medium sheet using the plate press or mating rolls to reduce the thickness of the filter medium sheet by between 20% and 90% in a region between 5% and 50% of the pleat depth and more preferably between 10% and 30% of the pleat depth.

[0032] The feature is that the production method can employ mating rolls having an eccentric device therebetween, the eccentric device compressing the filter medium sheet to a varying thickness. Alternatively, the method can also employ a plate press, wherein the plate press includes a varying thickness gap between opposing plates, the opposing plates compressing the filter medium sheet along the pleat to a varying thickness between the folds.

[0033] The feature is that the pleat layer can include only a single ply (e.g., a single deposition of fibers).

[0034] Alternatively, the pleat layer can also be a composite including at least two plies, the at least two plies including a first ply and a second ply laminated together, and optionally, the first ply and the second ply have different filtration properties.

[0035] Although the principles, embodiments, and operations of the present invention have been described in detail herein, this should not be construed as being limited to the specific illustrative forms disclosed. Thus, it will be apparent to those skilled in the art that various changes may be made to the embodiments herein without departing from the spirit or scope of the present invention.

[0036] Other aspects, objects, and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings incorporated in and forming a part of this specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:

[0038] Figure 1 is an exemplary cross-section along a plane of a symmetric / cylindrical filter element including a filter medium ring according to an embodiment of the present invention, the plane extending along / coinciding with the central axis of the filter;

[0039] Figure 2 is Figure 1 a cross-section of the filter medium ring and the central support tube portion of the filter element, showing the thicker and thinner portions, the cross-section being perpendicular to the central axis of the filter;

[0040] Figure 3 is similar to Figure 2 except that the filter medium is shown without the thicker and thinner portions and instead has a constant caliper thickness;

[0041] Figure 4 is a partial schematic side view / cross-sectional view of a flat press assembly according to an embodiment, the flat press assembly being used to form a filter medium sheet having thicker and thinner portions for use in Figure 1 and Figure 2 the filter element;

[0042] Figure 5 is Figure 4 a partial schematic side view / cross-sectional view of a roll die assembly according to an alternative embodiment, the roll die assembly also being used to form a filter medium sheet having thicker and thinner portions for use in Figure 1 and Figure 2 the filter element; and

[0043] Figure 6 is an isometric view of a formed sheet having thicker and thinner portions for use in Figure 1 and Figure 2 the filter element.

[0044] Figure 7 is similar toFigure 6 Similar ones can be used for Figure 1 and Figure 2 isometric views of the formed sheet having a thicker portion and a thinner portion in the filter element, but the formed sheet has steps with a profile between the thicker portion and the thinner portion and a radially extending section of constant thickness connected by a tapered section of the thinner portion.

[0045] Figure 8 is a cross-section of the filter medium and the central support tube portion of the same filter element showing the thicker and thinner portions, except that according to an alternative embodiment it has a filter medium layer that is a composite medium, the composite medium having a plurality of plies. Figure 2 Although the present invention will be described in connection with certain preferred embodiments, it is not intended to limit the present invention to these embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents included within the spirit and scope of the present invention as defined by the appended claims.

[0046] DETAILED DESCRIPTION DETAILED DESCRIPTION

[0047] As Figure 1-2 and Figure 6 shown, according to an embodiment of the present invention, a thicker portion 10 and a thinner portion 12 of the filter medium sheet 14 are provided in the filter element 16.

[0048] The filter medium sheet 14 includes a pleated layer of the filter medium 18 providing a plurality of pleats 20, each of the plurality of pleats extending between a first / inner pleat end 22 and a second / outer pleat end 24. When arranged as a filter medium pack, the first / inner pleat ends 22 are arranged adjacent to form a first / inner flow surface 26, and the second / outer pleat ends 24 are arranged to form a second / outer flow surface 28.

[0049] This arrangement can be used in panel-type elements, but as Figure 1 and Figure 2 shown is most advantageous when arranged as a ring 30, where the pleated layer of the filter medium 18 is wound around a central cavity 32 in such a way that the opposite cut ends of the filter medium sheet 14 are joined to each other. Such a filter medium ring arrangement as can be employed is shown, for example, in any of the following U.S. patents or patent publications: US4872976A, US5078877A, US5484466A, US20030015465A1, US20070084170A1, US20070163945A1, and US7740679B2 (all of these patents / patent publications are incorporated herein by reference in their entirety as examples of filter medium sheets 14 that can be used to provide a filter medium ring). Its features can be applied to different types of fluids, such as both air filters and liquid filters.

[0050] As Figure 2 and Figure 6 、 Figure 7 shown in, for example, comparison with Figure 3 the thickness of the pleats of the filter medium 18 varies as the medium extends vertically between the inner pleat end 22 and the outer pleat end 24 such that the thinner portion 12 of the filter medium extends from the pleat end 22 at the first / inner flow surface 26 towards the second / outer flow surface 28; and the thicker portion 10 of the filter medium extends from the second / outer pleat end 24 at the second / outer flow surface 28 towards the first / inner flow surface 26.

[0051] As is evident from the illustration, the thicker portion 10 of each pleat 30 is thicker than the thinner portion 12 of each pleat 30. As the thinner portion 12 extends perpendicular to the inner pleat end 22 and radially outwards, the filter medium of the pleat layer stops thinning at a point and thickens at the thicker portion 10; and thus as the filter medium extends radially outwards the thinner portion 12 merges into the thicker portion as shown in Figure 2 and Figure 6 and Figure 7 shown in.

[0052] The thickness of the filter medium sheet 14 may also vary continuously, as best shown in Figure 6 but it is also conceivable that the variation may occur only on a portion of the filter medium sheet 14, particularly in the region adjacent to the first / inner pleat end 22 at the first / inner flow surface 26, such as shown in Figure 7 shown in.

[0053] As can be seen in comparing Figure 2 and Figure 3 this may create an increased flow gap 34 to enhance the flow area due to the thickness reduction. When used in a filter medium arrangement according to Figure 1 this may reduce the pressure drop and provide a longer filter life.

[0054] Alternatively and / or additionally, the thinner portion 12 may also provide the ability to pack more filter medium into an annular shape such that the number of inner pleat ends 22 (e.g. around the filter support tube 26) can be increased as there is more space for additional inner pleat ends due to the thinner medium portion 12 creating more space at the inner periphery. Thus, more pleats and thus more filter medium can be packed, which allows for an increase in the filtering capacity as there is more available surface area for the fluid to pass through and for the loading of the filtered out particles. Thus, in some embodiments the creation of an increased flow gap 34 may not be achieved.

[0055] For an increased flow gap and / or an increased medium / pleat pack, this is particularly advantageous when used in combination with the central support tube 36. In the case where the filter medium ring 30 is disposed around the central support tube 36, the central support tube can predetermine the inner diameter of the pleated filter medium ring 30. When there is a radially inward flow (e.g., of a fluid such as fuel, oil, other liquids, air, or other gases), the central support tube 26 can then support and prevent the filter medium ring 30 from collapsing inward, and when support is required due to fluid flow and pressure differentials, the first / inner flow surface 26 (e.g., the inner pleat tip 22) contacts the support tube 36.

[0056] The central support tube 26 is porous, e.g., perforated with a plurality of flow holes 38 to allow fluid to pass radially inward into the central cavity 32 and along the central axis of the filter element 16.

[0057] The filter element 16 may further include opposite end caps, e.g., an open end cap 40 and a closed end cap 42, which may be integrally joined to opposite ends of the filter medium ring 30 and integrally joined to the central support tube 26 at the opposite ends (e.g., by an adhesive 44 retained in an annular well of the end cap).

[0058] For many applications in traditional air or liquid filtration applications, the central support tube 26 may have an outer diameter between 1 centimeter and 40 centimeters (and the inner diameter of the filter medium ring 30 would be the same).

[0059] The open end cap 40 allows the filtered fluid to exit, and the closed end cap 42 can ensure that the fluid is directed axially towards an opening in the open end cap 20, which may be surrounded by an annular gasket 46, which may be carried by or integral with the open end cap 40 to facilitate sealing to an external mounting head, pipe, and / or housing.

[0060] Returning to the nature of the variable-thickness pleated filter medium sheet 14, it is shown that the pleat layers have a thinner portion 12 and a thicker portion 10.

[0061] In a first region 48 adjacent to the first / inner pleat tip 22, the thinner portion 12 has a thickness that is thinner relative to the median thickness over a radially extending span, and in a second region 50, the thicker portion 10 has a thickness that is as thick or thicker relative to the median thickness over a radially extending span.

[0062] The thickness of the pleat layer can vary continuously between the pleat tips, as Figure 6 shown, or it can also vary in a discontinuous manner, as Figure 7As shown (e.g., it is also shown that the thicker portion of the medium adjacent the outer fold end may include a portion having a constant unchanged thickness and optionally a radially inward thinner portion of constant compressed thickness). The thinner first region 48 ends well short of the second outer fold end 24. The reduced thickness of the thinner portion 12 may extend (e.g., the span of the thickness reduction region 48 relative to the median thickness) at least 5% of the fold depth 60, as Figure 6 and Figure 7 shown. The thickness reduction region 48 of the thinner portion 12 may extend up to 50% (or possibly more) of the fold depth 60, as Figure 6 shown. However, the benefit of reducing crowding at the inner fold end is benefited from the thickness reduction of the filter medium sheet in the region immediately adjacent the inner fold end. Thus, the thickness reduction region 48 of the thinner portion 12 will more generally extend between 10% and 30% of the fold depth 60, as shown in Figure 7 .

[0063] Optionally, the pleat layers vary in the thicker portion 10 in the second region 50 of the second outer fold end 24, as Figure 6 shown. Alternatively, it may be beneficial not to compress the medium in the thicker second 50 (as Figure 7 shown), where the thicker portion 10 and the thicker second region 50 remain all or mostly uncompressed and may establish / match the median thickness.

[0064] The span of the thickness reduction region 48 is determined as the span below the median thickness for the thickness reduction region 48 starting from the inner fold end, as shown in Figure 6 and Figure 7 in two alternative embodiments. The span of the thickness increase region 50 is determined as the span at or above the median thickness starting from the outer fold end, as shown in Figure 6 and Figure 7 in two alternative embodiments.

[0065] Preferably, the pleat score 52 is formed (e.g., by a scoring bar on a roll / platen die, as Figure 4 and Figure 5 shown) to provide pre-determined folding positions for the inner fold end 22 and the outer fold end 24, which are shown in Figure 6 of the embodiment (and not shown in Figure 2 , and / or in an embodiment the scoring may alternatively be excluded to facilitate folding). These scores promote creasing by weakening and / or creating weakened regions (such as local indentations) into the filter medium sheet 14.

[0066] When pleat scores are provided at the pleat ends 22, 24, the thicker portions 10 and the thinner portions 12 at the respective pleat ends 22, 24 extend outwardly from the pleat score 52 and are adjacent to the pleat score.

[0067] Accordingly, and as used herein, the thicker portion 10 and the thinner portion 12 are determined independently of the score 52 feature for folding / gathering. In other words, the score 52 is excluded in identifying and considering the relative thickness at the regions of the inner fold end 22 and the outer fold end 24 (and similarly excluded in identifying and considering the relative thickness of the thicker portion 10 and the thinner portion 12). The score 52 may be formed into the thicker portion 10 or the thinner portion 12, but the score 52 is not considered when comparing, measuring, and / or determining the thicker portion 10 or the thinner portion 12.

[0068] For example, as shown, the score 52 for the outer fold end 24 creates a very localized region / line for folding that may be thinner than the thinner portion 12. However, in the sense of comparison with the thinner portion 12 of the filter medium sheet 14 at the inner fold end 12, the thin score 52 for the outer fold end 24 is excluded and not considered as part of the thicker portion (as compared with the thicker portion 10 at the outer fold end 24). Similarly, in the sense of comparing the thinner portion 12 with the thicker portion 10, the thin score 52 for the inner fold end 22 is excluded and not considered as part of the thinner portion 12.

[0069] With these understandings, and as best shown in Figure 6 and Figure 7 (with score) and Figure 2 (without score), the thicker portion 10 has a maximum thickness 56, which preferably may be the unchanged medium thickness before the thickness is reduced to form the thinner portion 12 (or alternatively a thickness slightly reduced from the unchanged thickness), generally somewhere between 0.2 mm and 5.1 mm; and in forming the thinner portion 12, the thickness reduction for the minimum thickness 58 may be between 20% and 90% of the maximum thickness 56. Preferably, the thinner portion has a minimum thickness 58 that is at least 50% less than the maximum thickness 56.

[0070] As described above, the thickness reduction is more important for the inner fold end 22, and when the filter medium extends in the first region 48, the filter medium has a reduced thickness, the first region being shown to extend from the first inner flow surface 26 towards the second outer flow surface 28 over at least 5% of the fold depth 60, which may be up to 50% of the fold depth (more generally, between 10% and 30% is most advantageous for the inner fold end aggregation advantage). For example, as Figure 6 shown, as the filter medium extends from the inner fold end 22 to the outer fold end 24, the filter medium has a gradually increasing thickness; and for example, as Figure 7 shown, the filter medium has a stepped thickness change region.

[0071] For many of the conventional pleated ring examples, such as many of those cited in the patents / publications above, the filter pack (e.g., the pleated filter media ring 30) has a pleat depth 60 extending between pleat tips at the first and second flow surfaces that is between 0.9 cm and 7.7 cm.

[0072] For many of the conventional pleated ring examples, such as many of those cited in the patents / publications above, the maximum caliper thickness of the filter media sheet 14 (i.e., the same thickness as the maximum thickness 26) is most typically between 0.2 mm and 5.1 mm.

[0073] While variations in the pleat depth direction are useful, variations in the perpendicular direction (e.g., the span between end caps 40, 42) are not required. Thus, as can be seen in Figure 6 the thickness T of the thinner portion 12 at different locations in the first region 48 across the span 62 between opposite sides of the filter media sheet 14 (e.g., the span 62 is parallel to the pleat tips) can remain substantially constant (e.g., constant or varying less than 10%).

[0074] In addition, the filter media can be without protrusions and have opposite generally flat surfaces 64 intermediate the pleat tips 22, 24, as shown in Figure 6 and Figure 2 By "generally flat" is meant without discrete protrusions having a depth greater than the thickness of the media sheet. However, the term "generally flat" optionally allows the use of "slotted / wrinkled" rollers that are sometimes used to create shallow continuous corrugations / grooves in the filter media sheet, which corrugations / grooves typically extend perpendicular to the pleat tips and which have a groove depth that is substantially less than the maximum thickness of the filter media sheet (e.g., the unaltered thickness).

[0075] To maximize the size of the beneficial flow gap 34, the thinner portion 12 is thinnest at the apex adjacent the inner pleat tip 22 (e.g., such as the location of the pleat score 52) and thickens in extent over at least a portion of the pleat 20 on the first region 48 toward the outer pleat tip 24.

[0076] As shown in Figure 4 and Figure 5 either (and then also referring to Figure 1 and Figure 2 ), a method of creating a filter media pack includes: creating a thicker portion 10 and a thinner portion 12 of a filter media sheet 14, such as by Figure 4 and Figure 5in any one of the ways; folding the filter medium sheet 14 at the thinner portion 12 and folding the filter medium sheet 14 at the thicker portion 10, thereby forming pleats 20 between the folds at the thinner and thicker portions; and wrapping the filter medium package into an annular shape (e.g., filter medium ring 30) in such a way that the thinner portion 12 is at the inner radial periphery and the thicker portion 10 is at the outer radial periphery, as from Figure 1 and Figure 2 apparent.

[0077] To facilitate pleating, the method preferably utilizes scoring of the filter medium package at score lines 52, the score lines including a first score line in the middle of the thinner portion 12 and a second score line in the middle of the thicker portion 10, wherein folding is facilitated along the first and second score lines.

[0078] In Figure 4 or Figure 5 the method involves conveying the filter medium sheet 14 along a forward path to a plate press 66 (e.g., upper platen 68 and lower platen 70) or a pair of mating rollers 72, 74. Using the plate press 66 or the mating rollers 72, 74, either of these devices can facilitate compressing the filter medium sheet 14 to reduce the thickness of the filter medium sheet by between 20% and 90% in a region between at least 5% and up to 50% of the pleat depth 60.

[0079] As Figure 5 shown, the method employs mating rollers 72, 74 having an eccentric device 76 therebetween, the eccentric device compressing the filter medium sheet to a varying thickness and may also have a scoring bar 78 to facilitate the formation of the score lines 52.

[0080] As Figure 4 shown, when a plate press 66 is employed, wherein the plate press includes a varying thickness gap 80 between opposing plates 68, 70, the opposing plates compressing the filter medium sheet along the pleats to a varying thickness between the folds. One or both of the plates may also have a scoring bar 82 to facilitate the formation of the score lines 52. Figure 4 Embodiments of

[0081] As Figure 2 shown, the filter medium sheet 14 and its pleated layers 18 of filter medium may include only a single layer of filter medium, which may be a homogeneous deposition of filter medium fibers (e.g., cellulose fibers, polymer / synthetic fibers, glass fibers, additives (binders, adsorbents, sorbents, etc.) or mixtures thereof).

[0082] Alternatively, as Figure 8As shown, the filter medium sheet 14a and the pleats of its filter medium 18a can be composites, including at least two sheets, the at least two sheets including a first and a second sheet laminated together (e.g., the sheets 81, 82, 83 laminated together as shown). Sheets 81 and 83 are schematically shown as the same filter medium fiber sheets or mesh sheets and can have the same filtration performance (or alternatively different filtration performance, if desired), while sheet 82 has filter medium fibers with a different filtration performance from sheets 81, 83. Each sheet can be a deposition of filter medium fibers (e.g., cellulose fibers, polymer / synthetic fibers, glass fibers, additives (binders, adsorbents, sorbents, etc.) or mixtures thereof) or a screen / mesh.

[0083] As will be apparent, Figure 8 the embodiments of and the filter medium sheet 14a can also be used in Figure 1-7 the embodiments for a single sheet sheet 14 such that the previous description of Figure 1-7 also applies thereto and vice versa. For example, pleat ends with a thicker portion and a thinner portion are also created, as shown in a Figure 8 similar manner to the previous embodiments.

[0084] All references cited herein, including publications, patent applications, and patents, are hereby incorporated by reference as if each reference were individually and specifically indicated to be incorporated by reference and the full text thereof were set forth herein.

[0085] Unless otherwise indicated herein or clearly contradicted by the context, the use of the terms "a" and "the" and "this" and similar referents in the context of describing the invention (especially in the context of the appended claims) shall be construed to cover both the singular and the plural. Unless otherwise specified, the terms "comprising," "having," "including," and "containing" shall be construed as open-ended terms (i.e., meaning "including but not limited to"). Unless otherwise indicated herein, the recitation of a range of values herein is merely intended to be a shorthand method of referring individually to each separate value falling within the range, and each separate value is incorporated into the specification as if it were individually recited herein. Unless otherwise indicated herein or otherwise clearly contradicted by the context, all methods described herein can be performed in any suitable order. The use of any and all example or exemplary language (e.g., "such as") provided herein is merely intended to better illuminate the invention and does not limit the scope of the invention unless otherwise claimed. No language in this specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0086] Preferred embodiments of the invention are described herein, including the best mode known to the inventors for practicing the invention. Variations of these preferred embodiments will become apparent to those of ordinary skill in the art after reading the foregoing description. The inventors expect those skilled in the art to adopt such variations as appropriate, and the inventors also intend for the invention to be practiced in a manner different from that specifically described herein. Accordingly, the invention includes all modifications and equivalents of the subject matter recited in the appended claims as permitted by applicable law. In addition, unless otherwise indicated herein or otherwise clearly contradicted by context, any combination of the above elements in all possible variations thereof is included in the invention.

Claims

1. A filter element includes a filter medium ring disposed around a central support tube. The filter medium includes pleats of the medium, and the pleats include inner pleat ends adjacent to the tube and outer pleat ends radially spaced outwardly from the tube. The thickness of the pleats varies between the ends such that a portion of the medium is thinner at the inner pleat ends than at the outer pleat ends.

2. The filter element according to claim 1, wherein Pleat creases are at the inner pleat ends and the outer pleat ends, and the thinner portion of the medium has pleat creases adjacent to the inner pleat ends compared to the pleat creases of the thicker portion of the medium adjacent to the outer pleat ends.

3. The filter element according to claim 2, wherein, Outside the pleat creases, the thinner portion has a minimum thickness that is 20% to 90% thinner than the maximum thickness of the thicker portion.

4. The filter element according to claim 1, wherein, The filter medium has a thickness that gradually increases as the filter medium extends radially outward from the inner pleat ends to the outer pleat ends.

5. The filter element according to claim 1, wherein As the filter medium extends radially outward from the inner pleat ends to the outer pleat ends, the thickness of the filter medium changes in a stepped manner.

6. The filter element according to claim 1, wherein, The thicker portion of the medium adjacent to the outer pleat ends includes a portion having a constant and unchanged thickness.

7. The filter element according to claim 1, wherein, There is provided a thicker portion of the medium that is thicker than the thinner portion, and the thinner portion is 20% to 90% thinner than the maximum thickness of the thicker portion.

8. The filter element according to claim 1, wherein, The filter medium includes: A pleat depth extending between the inner pleat ends and the outer pleat ends between 0.9 cm and 7.7 cm; A maximum caliper thickness between 0.2 mm and 5.1 mm; and Wherein the central support tube has an outer diameter between 1 cm and 40 cm.

9. The filter element according to claim 1, wherein, The thickness of the thinner portion remains substantially constant across the span of the filter medium ring, and the span is parallel to the pleat ends.

10. The filter element according to claim 1, wherein, The filter medium has no protrusions and has opposite generally flat surfaces at the middle of the pleat ends.

11. The filter element according to claim 1, wherein, The thinner portion extends between 5% and 50% of the pleat depth of the pleat layer, and preferably extends between 10% and 30% of the pleat depth of the pleat layer.

12. The filter element according to claim 1, wherein, The thinner portion forms a space at the inner peripheral edge of the ring to provide a greater flow gap between adjacent inner pleat ends and / or more filter medium with more pleats is used in the ring.

13. The filter element according to claim 1, wherein, As the thinner portion extends radially outward perpendicular to the inner pleat ends, the thinner portion merges into the thicker portion.

14. The filter element according to claim 1, wherein, The pleat layer includes only a single sheet.

15. The filter element according to claim 1, wherein, The pleat layer includes a composite having at least two sheets, and the at least two sheets include a first sheet and a second sheet laminated together, and the first sheet and the second sheet have different filtration properties.

16. A filter medium sheet includes: Pleats of the filter medium, the pleats including pleat ends at opposite first and second flow surfaces, the pleats including a thinner portion of the filter medium extending from the pleat end at the first flow surface toward the second flow surface, and a thicker portion of the filter medium extending from the pleat end at the second flow surface toward the first flow surface, and the thicker portion is thicker than the thinner portion.

17. The filter medium sheet according to claim 16, wherein, The thinner portion has a minimum thickness that is 20% to 90% thinner than the maximum thickness of the thicker portion.

18. The filter medium sheet according to claim 16, wherein, Pleat creases are provided at the pleat ends, and the thinner and thicker portions of the filter medium extend from the respective pleat creases.

19. The filter medium sheet according to claim 16, wherein, The filter medium has a thickness that gradually increases as the filter medium extends vertically from the pleat end at the first flow surface to the pleat end at the second flow surface.

20. The filter medium sheet according to claim 16, wherein, As the filter medium extends vertically from the pleat end at the first flow surface to the pleat end at the second flow surface, the thickness of the filter medium changes in a stepped manner.

21. The filter medium sheet according to claim 16, wherein, As the filter medium extends vertically from the pleat end at the first flow surface to the pleat end at the second flow surface, the filter medium has a thickness that is gradually increasing and tapered over at least a portion of the pleat depth.

22. The filter medium sheet according to claim 16, wherein, The filter medium comprises: a pleat depth extending between the pleat ends at the first and second flow surfaces between 0.9 cm and 7.7 cm; a maximum caliper thickness between 0.2 mm and 5.1 mm.

23. The filter medium sheet according to claim 16, wherein, The thickness of the thinner portion remains substantially constant across the span of the filter medium sheet, the span being parallel to the pleat ends.

24. The filter medium sheet according to claim 16, wherein, The filter medium has no protrusions and has opposite, generally flat surfaces in the middle of the pleat ends.

25. The filter medium sheet according to claim 16, wherein, The thinner portion extends between 5% and 50% of the pleat depth of the pleat layer, and preferably between 10% and 30% of the pleat depth of the pleat layer.

26. A filter element, comprising a filter medium sheet as described in claim 16, wherein, The filter medium sheet is wound into a ring and defines a central cavity, the radially inner periphery of the ring being provided by the pleat end at the first flow surface, and the radially outer periphery of the ring being provided by the pleat end at the second flow surface that is radially outwardly spaced from the inner radial periphery.

27. The filter element according to claim 16, wherein, The pleat layer comprises only a single sheet.

28. The filter element according to claim 16, wherein The pleat layer comprises a composite having at least two sheets, the at least two sheets including a first sheet and a second sheet laminated together, the first sheet and the second sheet having different filtration properties.

29. A method of creating a filter medium pack, comprising: creating a thicker portion and a thinner portion of a filter medium sheet, the thicker portion being thicker than the thinner portion; folding the filter medium sheet at the thinner portion; folding the filter medium sheet at the thicker portion, thereby creating a pleat between the folds at the thinner portion and the thicker portion; and wrapping the filter medium pack into an annular shape with the thinner portion at the inner radial periphery and the thicker portion at the outer radial periphery.

30. The method according to claim 29, further comprising scoring the filter media pack at a first score line intermediate the thinner portion and at a second score line intermediate the thicker portion, wherein, Facilitating the folding along the first score and the second score.

31. The method of claim 29, further comprising: feeding the filter medium sheet along a forward path to a plate press or mating rolls; compressing the filter medium sheet using the plate press or the mating rolls to reduce the thickness of the filter medium sheet by between 20 and 90% in a region between 5% and 50% of the pleat depth of the pleat, and more preferably between 10% and 30% of the pleat depth of the pleat.

32. The method according to claim 31, wherein, The method employs mating rolls having an eccentric device therebetween, the eccentric device compressing the filter medium sheet to a varying thickness.

33. The method according to claim 29, wherein, The plate press is employed, wherein the plate press includes a varying thickness gap between opposing plates that compress the filter medium sheet along the pleat to a varying thickness between the folds.

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