CROSS-REFERENCE TO RELATED APPLICATION

[0001] This patent application claims the benefit of U.S. Provisional Patent Application No. 63/395,090, filed August 4, 2022, which is incorporated by reference in its entirety herein.

BACKGROUND OF THE INVENTION

[0002] There is a need in the art for improved pleated filter elements.

[0003] The present invention provides for ameliorating at least some of the disadvantages of the prior art. These and other advantages of the present invention will be apparent from the description as set forth below.

BRIEF SUMMARY OF THE INVENTION

[0004] An aspect of the invention provides a cylindrical porous filter comprising an inner core and an outer cage, with an annular gap between the inner core and the outer cage, with a cylindrical hollow porous pleated filter element arranged in the annular gap between the inner core and the outer cage, the annular gap having a width; wherein the cylindrical hollow porous pleated filter element has first and second end surfaces, the cylindrical hollow porous pleated filter element comprising a plurality of filter element groups, each of the plurality of filter element groups comprising a forward filter element group and a rear filter element group, the forward filter element group comprising a first forward bridge having a first forward bridge height, followed by a first longitudinal counter-pleat having a first longitudinal counter-pleat height, a second longitudinal counter-pleat having a second longitudinal counter-pleat height, a third longitudinal counter-pleat having a third longitudinal counter-pleat height, wherein the third longitudinal counter-pleat height has a greater height than each of the first longitudinal counter-pleat height and the second longitudinal counter-pleat height, the second longitudinal counter-pleat height has a lesser height than each of the first longitudinal counter-pleat height and the third longitudinal counter-pleat height, and the first longitudinal counter-pleat height has a height greater than the second longitudinal counter-pleat height and lesser than the third longitudinal counter-pleat height; the rear filter element group comprising a first rear bridge having a first rear bridge height, followed by a first longitudinal pleat having a first longitudinal pleat height, a second longitudinal pleat having a second longitudinal pleat height, a third longitudinal pleat having a third longitudinal pleat height, wherein the third longitudinal pleat height has a greater height than each of the first longitudinal pleat height and the second longitudinal pleat height, the second longitudinal pleat height has a lesser height than each of the first longitudinal pleat height and the third longitudinal pleat height, and the first longitudinal pleat height has a height greater than the second longitudinal pleat height and lesser than the third longitudinal pleat height; wherein the first forward bridge height is greater than the first rear bridge height; the first forward bridge, the first, second, and third longitudinal counter-pleats, the first rear bridge, and the first, second, and third longitudinal pleats, being in a laid-over state; and each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height are different heights than heights of each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height; and wherein each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any filter element group, are different heights than heights of each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any other filter element group.

[0005] In an aspect, each first forward bridge has a front first forward bridge surface and a rear first forward bridge surface; each of the longitudinal counter-pleats has a pair of adjoining longitudinal counter-pleat legs, each of the longitudinal counter-pleat legs having a first longitudinal counter-pleat leg surface and a second longitudinal counter-pleat leg surface; each first rear bridge has a front first rear bridge surface and a rear first rear bridge surface; each the longitudinal pleats has a pair of adjoining longitudinal pleat legs, each of the longitudinal pleat legs having a first longitudinal pleat leg surface and a second longitudinal pleat leg surface; the first forward bridge, the longitudinal counter-pleats, the first rear bridge, and the longitudinal pleats, being in a laid-over state in which a longitudinal counter-pleat leg surface of one longitudinal counter-pleat is in intimate contact with at least one of any of a longitudinal pleat leg surface of an adjoining leg of the one longitudinal counter-pleat, a longitudinal counter-pleat leg surface of an adjacent longitudinal counter-pleat, a rear first forward bridge surface, and a front first rear bridge surface; and, a longitudinal pleat leg surface of one longitudinal pleat is in intimate contact with at least one of any of a longitudinal pleat leg surface of an adjoining leg of the one longitudinal pleat, a longitudinal pleat leg surface of an adjacent longitudinal pleat, a front first forward bridge surface, and a front first rear bridge surface.

[0006] In another aspect, a cylindrical hollow porous pleated filter element is provided, the cylindrical hollow porous pleated filter element comprising a plurality of filter element groups, each of the plurality of filter element groups comprising a forward filter element group and a rear filter element group, the forward filter element group comprising a first forward bridge having a first forward bridge height, followed by a first longitudinal counter-pleat having a first longitudinal counter-pleat height, a second longitudinal counter-pleat having a second longitudinal counter-pleat height, a third longitudinal counter-pleat having a third longitudinal counter-pleat height, wherein the third longitudinal counter-pleat height has a greater height than each of the first longitudinal counter-pleat height and the second longitudinal counter-pleat height, the second longitudinal counter-pleat height has a lesser height than each of the first longitudinal counter-pleat height and the third longitudinal counter-pleat height, and the first longitudinal counter-pleat height has a height greater than the second longitudinal counter-pleat height and lesser than the third longitudinal counter-pleat height; the rear filter element group comprising a first rear bridge having a first rear bridge height, followed by a first longitudinal pleat having a first longitudinal pleat height, a second longitudinal pleat having a second longitudinal pleat height, a third longitudinal pleat having a third longitudinal pleat height, wherein the third longitudinal pleat height has a greater height than each of the first longitudinal pleat height and the second longitudinal pleat height, the second longitudinal pleat height has a lesser height than each of the first longitudinal pleat height and the third longitudinal pleat height, and the first longitudinal pleat height has a height greater than the second longitudinal pleat height and lesser than the third longitudinal pleat height; wherein the first forward bridge height is greater than the first rear bridge height; and each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height are different heights than heights of each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height; and wherein each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any filter element group, are different heights than heights of each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any other filter element group.

[0007] In another aspect, a method of filtering fluid is provided, the method comprising passing the fluid through an aspect of a cylindrical porous filter comprising an inner core and an outer cage, with an annular gap between the inner core and the outer cage, with a cylindrical hollow porous pleated filter element arranged in the annular gap between the inner core and the outer cage, the annular gap having a width; wherein the cylindrical hollow porous pleated filter element has first and second end surfaces, the cylindrical hollow porous pleated filter element comprising a plurality of filter element groups, each of the plurality of filter element groups comprising a forward filter element group and a rear filter element group, the forward filter element group comprising a first forward bridge having a first forward bridge height, followed by a first longitudinal counter-pleat having a first longitudinal counter-pleat height, a second longitudinal counter-pleat having a second longitudinal counter-pleat height, a third longitudinal counter-pleat having a third longitudinal counter-pleat height, wherein the third longitudinal counter-pleat height has a greater height than each of the first longitudinal counter-pleat height and the second longitudinal counter-pleat height, the second longitudinal counter-pleat height has a lesser height than each of the first longitudinal counter-pleat height and the third longitudinal counter-pleat height, and the first longitudinal counter-pleat height has a height greater than the second longitudinal counter-pleat height and lesser than the third longitudinal counter-pleat height; the rear filter element group comprising a first rear bridge having a first rear bridge height, followed by a first longitudinal pleat having a first longitudinal pleat height, a second longitudinal pleat having a second longitudinal pleat height, a third longitudinal pleat having a third longitudinal pleat height, wherein the third longitudinal pleat height has a greater height than each of the first longitudinal pleat height and the second longitudinal pleat height, the second longitudinal pleat height has a lesser height than each of the first longitudinal pleat height and the third longitudinal pleat height, and the first longitudinal pleat height has a height greater than the second longitudinal pleat height and lesser than the third longitudinal pleat height; wherein the first forward bridge height is greater than the first rear bridge height; the first forward bridge, the first, second, and third longitudinal counter-pleats, the first rear bridge, and the first, second, and third longitudinal pleats, being in a laid-over state; and each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height are different heights than heights of each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height; and wherein each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any filter element group, are different heights than heights of each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any other filter element group.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

[0008] Figure 1 is a drawing showing, diagrammatically, a filter with a filter element having mixed bridge heights and mixed pleat heights (5 bridge heights and 8 pleat heights are shown), for use in preparing a filter element according to an aspect of the invention, (wherein, for ease of reference, the bridges and pleats are shown expanded before compression to form a pleated porous filter element, and an inner core and outer cage are also shown), showing an aspect of a pleated cylindrical hollow porous filter element arranged in an annular gap between the inner core and the outer cage, the annular gap having a width; the pleated cylindrical hollow porous filter element comprising a plurality of filter element groups, each of the plurality of filter element groups comprising a forward filter element group and a rear filter element group, the forward filter element group comprising a first forward bridge having a first forward bridge height, followed by a first longitudinal counter-pleat having a first longitudinal counter-pleat height, a second longitudinal counter-pleat having a second longitudinal counter-pleat height, a third longitudinal counter-pleat having a third longitudinal counter-pleat height, wherein the third longitudinal counter-pleat height has a greater height than each of the first longitudinal counter-pleat height and the second longitudinal counter-pleat height, the second longitudinal counter-pleat height has a lesser height than each of the first longitudinal counter-pleat height and the third longitudinal counter-pleat height, and the first longitudinal counter-pleat height has a height greater than the second longitudinal counter-pleat height and lesser than the third longitudinal counter-pleat height; the rear filter element group comprising a first rear bridge having a first rear bridge height, followed by a first longitudinal pleat having a first longitudinal pleat height, a second longitudinal pleat having a second longitudinal pleat height, a third longitudinal pleat having a third longitudinal pleat height, wherein the third longitudinal pleat height has a greater height than each of the first longitudinal pleat height and the second longitudinal pleat height, the second longitudinal pleat height has a lesser height than each of the first longitudinal pleat height and the third longitudinal pleat height, and the first longitudinal pleat height has a height greater than the second longitudinal pleat height and lesser than the third longitudinal pleat height; wherein the first forward bridge height is greater than the first rear badge height; the first forward bridge, the first, second, and third longitudinal counter-pleats, the first rear bridge, and the first, second, and third longitudinal pleats, being in a laid-over state; and each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height are different heights than heights of each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height; and wherein each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any filter element group, are different heights than heights of each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any other filter element group. As shown in this Figure, each of the pleats facing outwardly 100A, 200A, 3OOA, 400A, 5OOA, 600A having respective heights ((O)H1 -(O)H6), and each of the pleats facing inwardly 100B, 200B, 300B, 400B, 5OOB, 600B having respective heights ((I)Hl-(I)H6),and each of the bridges (B1-B5), have different heights and no heights or patterns are repeated (non-repeated units and non-symmetric orientation), according to an aspect of the invention.

[0009] Figure 2 is a photograph showing a computed tomography (CT) scan of an assembled filter element with mixed bridge heights and mixed pleat heights as generally shown in Figure 1.

[0010] Figure 3 is a drawing showing a cut-away diagrammatic perspective view of a filter including a filter element with mixed bridge heights and mixed pleat heights as generally shown in Figure 1 (filter element not fully compressed) and Figure 2, according to another aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0011] In accordance with an aspect of the invention, a cylindrical porous filter is provided comprising an inner core and an outer cage, with an annular gap between the inner core and the outer cage, with a cylindrical hollow porous pleated filter element arranged in the annular gap between the inner core and the outer cage, the annular gap having a width; wherein the cylindrical hollow porous pleated filter element has first and second end surfaces, the cylindrical hollow porous pleated filter element comprising a plurality of filter element groups, each of the plurality of filter element groups comprising a forward filter element group and a rear filter element group, the forward filter element group comprising a first forward bridge having a first forward bridge height, followed by a first longitudinal counter-pleat having a first longitudinal counter-pleat height, a second longitudinal counter-pleat having a second longitudinal counter-pleat height, a third longitudinal counter-pleat having a third longitudinal counter-pleat height, wherein the third longitudinal counter-pleat height has a greater height than each of the first longitudinal counter-pleat height and the second longitudinal counter-pleat height, the second longitudinal counter-pleat height has a lesser height than each of the first longitudinal counter-pleat height and the third longitudinal counter-pleat height, and the first longitudinal counter-pleat height has a height greater than the second longitudinal counter-pleat height and lesser than the third longitudinal counter-pleat height; the rear filter element group comprising a first rear bridge having a first rear bridge height, followed by a first longitudinal pleat having a first longitudinal pleat height, a second longitudinal pleat having a second longitudinal pleat height, a third longitudinal pleat having a third longitudinal pleat height, wherein the third longitudinal pleat height has a greater height than each of the first longitudinal pleat height and the second longitudinal pleat height, the second longitudinal pleat height has a lesser height than each of the first longitudinal pleat height and the third longitudinal pleat height, and the first longitudinal pleat height has a height greater than the second longitudinal pleat height and lesser than the third longitudinal pleat height; wherein the first forward bridge height is greater than the first rear bridge height; the first forward bridge, the first, second, and third longitudinal counter-pleats, the first rear bridge, and the first, second, and third longitudinal pleats, being in a laid-over state; and each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height are different heights than heights of each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height; and wherein each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any filter element group, are different heights than heights of each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any other filter element group.

[0012] In another aspect, a cylindrical hollow porous pleated filter element is provided, the cylindrical hollow porous pleated filter element comprising a plurality of filter element groups, each of the plurality of filter element groups comprising a forward filter element group and a rear filter element group, the forward filter element group comprising a first forward bridge having a first forward bridge height, followed by a first longitudinal counter-pleat having a first longitudinal counter-pleat height, a second longitudinal counter-pleat having a second longitudinal counter-pleat height, a third longitudinal counter-pleat having a third longitudinal counter-pleat height, wherein the third longitudinal counter-pleat height has a greater height than each of the first longitudinal counter-pleat height and the second longitudinal counter-pleat height, the second longitudinal counter-pleat height has a lesser height than each of the first longitudinal counter-pleat height and the third longitudinal counter-pleat height, and the first longitudinal counter-pleat height has a height greater than the second longitudinal counter-pleat height and lesser than the third longitudinal counter-pleat height; the rear filter element group comprising a first rear bridge having a first rear bridge height, followed by a first longitudinal pleat having a first longitudinal pleat height, a second longitudinal pleat having a second longitudinal pleat height, a third longitudinal pleat having a third longitudinal pleat height, wherein the third longitudinal pleat height has a greater height than each of the first longitudinal pleat height and the second longitudinal pleat height, the second longitudinal pleat height has a lesser height than each of the first longitudinal pleat height and the third longitudinal pleat height, and the first longitudinal pleat height has a height greater than the second longitudinal pleat height and lesser than the third longitudinal pleat height; wherein the first forward bridge height is greater than the first rear bridge height; and each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height are different heights than heights of each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height; and wherein each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any filter element group, are different heights than heights of each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any other filter element group.

[0013] In another aspect, a method of filtering fluid is provided, the method comprising passing the fluid through an aspect of a cylindrical porous filter comprising an inner core and an outer cage, with an annular gap between the inner core and the outer cage, with a cylindrical hollow porous pleated filter element arranged in the annular gap between the inner core and the outer cage, the annular gap having a width; wherein the cylindrical hollow porous pleated filter element has first and second end surfaces, the cylindrical hollow porous pleated filter element comprising a plurality of filter element groups, each of the plurality of filter element groups comprising a forward filter element group and a rear filter element group, the forward filter element group comprising a first forward bridge having a first forward bridge height, followed by a first longitudinal counter-pleat having a first longitudinal counter-pleat height, a second longitudinal counter-pleat having a second longitudinal counter-pleat height, a third longitudinal counter-pleat having a third longitudinal counter-pleat height, wherein the third longitudinal counter-pleat height has a greater height than each of the first longitudinal counter-pleat height and the second longitudinal counter-pleat height, the second longitudinal counter-pleat height has a lesser height than each of the first longitudinal counter-pleat height and the third longitudinal counter-pleat height, and the first longitudinal counter-pleat height has a height greater than the second longitudinal counter-pleat height and lesser than the third longitudinal counter-pleat height; the rear filter element group comprising a first rear bridge having a first rear bridge height, followed by a first longitudinal pleat having a first longitudinal pleat height, a second longitudinal pleat having a second longitudinal pleat height, a third longitudinal pleat having a third longitudinal pleat height, wherein the third longitudinal pleat height has a greater height than each of the first longitudinal pleat height and the second longitudinal pleat height, the second longitudinal pleat height has a lesser height than each of the first longitudinal pleat height and the third longitudinal pleat height, and the first longitudinal pleat height has a height greater than the second longitudinal pleat height and lesser than the third longitudinal pleat height; wherein the first forward bridge height is greater than the first rear bridge height; the first forward bridge, the first, second, and third longitudinal counter-pleats, the first rear bridge, and the first, second, and third longitudinal pleats, being in a laid-over state; and each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height are different heights than heights of each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height; and wherein each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any filter element group, are different heights than heights of each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any other filter element group; preferably, the method including obtaining the filtered fluid.

[0014] Aspects of the method can include outside-in flow in which a fluid to be filtered flows from the outer cage through the filter element into the inner core, or include inside-out flow in which fluid flows from the inner core through the filter element to the outer cage.

[0015] In a preferred aspect, a first impervious end cap is connected to the first end surface of the filter element.

[0016] In an aspect, in each of the plurality of filter groups, each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal counter-pleat height have heights that differ from each other by at least 5%.

[0017] In an aspect, each first forward bridge has a front first forward bridge surface and a rear first forward bridge surface; each of the longitudinal counter-pleats has a pair of adjoining longitudinal counter-pleat legs, each of the longitudinal counter-pleat legs having a first (outer) longitudinal counter-pleat leg surface and a second (inner) longitudinal counter-pleat leg surface; each first rear bridge has a front first rear bridge surface and a rear first rear bridge surface; each the longitudinal pleats has a pair of adjoining longitudinal pleat legs, each of the longitudinal pleat legs having a first (outer) longitudinal pleat leg surface and a second (inner) longitudinal pleat leg surface; the first forward bridge, the longitudinal counter-pleats, the first rear bridge, and the longitudinal pleats, being in a laid-over state in which a longitudinal counter-pleat leg surface of one longitudinal counter-pleat is in intimate contact with at least one of any of a longitudinal pleat leg surface of an adjoining leg of the one longitudinal counter-pleat, a longitudinal counter-pleat leg surface of an adjacent longitudinal counter-pleat, a rear first forward bridge surface, and a front first rear bndge surface; and, a longitudinal pleat leg surface of one longitudinal pleat is in intimate contact with at least one of any of a longitudinal pleat leg surface of an adjoining leg of the one longitudinal pleat, a longitudinal pleat leg surface of an adjacent longitudinal pleat, a front first forward bridge surface, and a rear first rear bridge surface. [0018] While the bridges all have heights that differ from one another, all of them have bridge heights that are greater than the annular gap between the inner core and the outer cage.

[0019] Advantageously, filter elements, filters including the filter elements, and filter devices including the filters, can have lower packing densities and higher permeabilities while maintaining desirable pressure differentials and reducing membrane area, while edge-flow resistance is reduced.

[0020] Each of the components of the invention will now be described in more detail below, wherein like components have like reference numbers.

[0021] Figure 1 illustrates, diagrammatically (wherein, for ease of reference, the pleats are shown expanded before compression to form the pleated porous filter element), an aspect of a pleated cylindrical hollow porous filter element 3000 is arranged in the annular gap G between a perforated inner core 800 and an outer cage 900, the annular gap having a width W; the pleated cylindrical hollow porous filter element having a longitudinal axis (see, Fig. 3) and first and second end surfaces, the cylindrical hollow porous pleated filter element comprising a plurality of filter groups GRP1, GRP2, GRP3;

[0022] each of the plurality of filter element groups comprising a forward filter element group SGI (GRP1), SG3 (GRP2) SG5 (GRP5) and a rear filter element group SG2 (GRP1), SG4 (GRP2), (SG6 (GRP2) not shown);

[0023] the forward filter element group SGI, SG3 comprising, respectively, a first forward bridge Bl, B3 (B5 in GRP3) having a first forward bridge height BH1, BH3 (BH5 in GRP3), followed by a first longitudinal counter-pleat 100A, 400A having a first longitudinal counter-pleat height (O)H1 , (O)H4, a second longitudinal counter-pleat 200 A, 500A, having a second longitudinal counter-pleat height (O)H2, (O)H5, a third longitudinal counter-pleat 300 A, 600 A having a third longitudinal counter-pleat height (O)H3, (O)H6, wherein the third longitudinal counter-pleat height has a greater height than each of the first longitudinal counter-pleat height and the second longitudinal counter-pleat height, the second longitudinal counter-pleat height has a lesser height than each of the first longitudinal counter-pleat height and the third longitudinal counter-pleat height, and the first longitudinal counter-pleat height has a height greater than the second longitudinal counter-pleat height and lesser than the third longitudinal counter-pleat height; [0024] the rear filter element group SG2, SG4 comprising, respectively, a first rear bridge B2, B4, having a first rear bridge height BH2, BH4, followed by a first longitudinal pleat 100B, 400B having a first longitudinal pleat height (I)H1, (I)H4, a second longitudinal pleat 200B, 500B, having a second longitudinal pleat height (I)H2, (I)H5, a third longitudinal pleat 300B, 600B having a third longitudinal pleat height (I)H3, (I)H6, wherein the third longitudinal pleat height has a greater height than each of the first longitudinal pleat height and the second longitudinal pleat height, the second longitudinal pleat height has a lesser height than each of the first longitudinal pleat height and the third longitudinal pleat height, and the first longitudinal pleat height has a height greater than the second longitudinal pleat height and lesser than the third longitudinal pleat height;

[0025] wherein the first forw ard bridge height BH1, BH3, is greater than the first rear bridge height BH2, BH4;

[0026] the first forward bridge, the first, second, and third longitudinal counter-pleats, the first rear bridge, and the first, second, and third longitudinal pleats, being in a laid-over state; and;

[0027] each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height are different heights than heights of each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height; and

[0028] wherein each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat at height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any filter element group, are different heights than

[0029] heights of each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height, and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal pleat height, in any other filter element group; [0030] the first forward bridge, the longitudinal counter-pleats, the first rear bridge, and the longitudinal pleats, being in a laid-over state (shown in Figure 3).

[0031] In an aspect, in each of the plurality of filter groups, each of the first forward bridge height, the first longitudinal counter-pleat height, the second longitudinal counter-pleat height, and the third longitudinal counter-pleat height and each of the rear forward bridge height, the first longitudinal pleat height, the second longitudinal pleat height, and the third longitudinal counter-pleat height have heights that differ from each other by at least 5%, in another aspect, heights that differ from each other by at least 10%.

[0032] In accordance with this illustrated aspect, each of the pleats facing outwardly 100 A, 200 A, 300 A, 400A, 500 A, 600A having respective heights ((O)H1-(O)H6), and each of the pleats facing inwardly 100B, 200B, 300B, 400B, 500B, 600B having respective heights ((l)Hl-(l)H6),and each of the bridges (B1-B5), have different heights and no heights or patterns are repeated (non-repeated units and non-symmetric orientation), according to an aspect of the invention, wherein the filter element has any suitable number of filter groups.

[0033] In some aspects, the filter elements have at least 40 groups, typically at least 46 groups.

[0034] Each pleat comprises a pair of legs, each leg having a first (outer) surface, and a second (inner) surface (thus, the legs have opposing interior surfaces and opposing exterior surfaces), a leg length, and a crown or tip where the legs meet (adjoined) and the pleat is folded over. Each leg has a root abutting the core (for longitudinal counter-pleats) or cage (longitudinal pleats), and the pleats extend axially from the core or cage, respectively.

[0035] As will be discussed in more detail below, and shown in, for example, Figure 3, the formed filter element will have laid-over pleats. Accordingly, the first forward bridge, the longitudinal counter-pleats, the first rear bridge, and the longitudinal pleats, are in a laid-over state in which a longitudinal counter-pleat leg surface of one longitudinal counter-pleat is in intimate contact with at least one of any of a longitudinal counter-pleat leg surface of an adjoining leg of the one longitudinal counter-pleat, a longitudinal counter-pleat leg surface of an adjacent longitudinal counter-pleat, a rear first forward bridge surface, and a front first rear bridge surface; and, a longitudinal pleat leg surface of one longitudinal pleat is in intimate contact with at least one of any of a longitudinal pleat leg surface of an adjoining leg of the one longitudinal pleat, a longitudinal pleat leg surface of an adjacent longitudinal pleat, a front first forward bridge surface, and a rear first rear bridge surface.

[0036] Typically, each second (inner) longitudinal counter-pleat leg surface of one longitudinal counter-pleat is in intimate contact with a second (inner) longitudinal counter-pleat leg surface of an adjoining leg of the one longitudinal counter-pleat, and a first (outer) counter-pleat leg surface of one longitudinal counter-pleat may also be in intimate contact with a first (outer) longitudinal counter-pleat leg surface of an adjacent longitudinal counter-pleat, a rear first forward bridge surface, and a front first rear bridge surface; and/or each second (inner) longitudinal pleat leg surface of one longitudinal pleat is in intimate contact with a second (inner) longitudinal pleat leg surface of an adjoining leg of the one longitudinal pleat, and a first (outer) pleat leg surface of one longitudinal pleat may also be in intimate contact with a first (outer) longitudinal pleat leg surface of an adjacent longitudinal pleat, a front first forward bridge surface, and a rear first rear bridge surface.

[0037] Illustratively, using the aspect illustrated in Figure 1 for reference, in the laid-over state, the rear first forward bridge surface will be in intimate contact with the first (outer) longitudinal counter-pleat leg surface of the first longitudinal counter-pleat leg of the following longitudinal counter-pleat (100 A), the second (inner) longitudinal counter-pleat leg surface of the first longitudinal counter-pleat leg will be in intimate contact with the second (inner) longitudinal counter-pleat leg surface of the adjoining second longitudinal counter-pleat leg of that longitudinal counter-pleat (100A). The first (outer) longitudinal counter-pleat leg surface of the second longitudinal counter-pleat leg of that longitudinal counter-pleat (100 A) will be in intimate contact with the first (outer) longitudinal counter-pleat leg surface of the first longitudinal counter-pleat leg of the following (adjacent) longitudinal counter-pleat (200A), and so on with reference to Figure 1, e.g., the front first rear bridge surface will be in intimate contact with the first (outer) longitudinal counter-pleat leg surface of the second longitudinal pleat leg of the longitudinal counter-pleat (300A) following longitudinal counter-pleat (200A), and the rear first rear bridge surface will be in intimate contact with the first (outer) longitudinal pleat leg surface of the first longitudinal pleat leg of the following (adjacent) longitudinal pleat (100B). [0038] Using Figures 1, 2, and 3 for reference (Figure 2 showing a fully compressed filter element with laid over pleats), a cylindrical perforated inner core 800 is coaxially disposed along the inner periphery of the pleated porous filter element 3000, and a cylindrical cage 900 is disposed along the outer periphery of the filter element, and an annular gap G is present between the inner core and the outer cage, with the pleated porous filter element arranged in the gap between the inner core and the outer cage, the gap having a width W.

[0039] In the assembled filter element, the longitudinal pleats are bent near their tips (facing the inner core) and the longitudinal counter-pleats are bent near their tips (facing the outer cage) as part of the laid-over pleat.

[0040] The opposing surfaces of adjoining legs of the pleats need not be in intimate contact over the entire axial length of the filter element, but the greater is the length in the axial direction of the region of intimate contact, the more effectively used is the space between the inner and outer periphery of the filter element 3000. Therefore, adjoining legs are in intimate contact over a continuous region which can extend for at least approximately 50%, in some aspects, at least approximately 75%, or approximately 95-100% of the axial length of the filter element 3000.

[0041] There are no particular restrictions on the type of porous filter medium 500 (see, Fig. 3) which can be employed in the porous filter element of the present invention, and it can be selected in accordance with the fluid which is to be filtered and the desired filtering characteristics. Preferably, the porous filter medium/filter element comprises a polymeric medium. The filter element/filter can be used to filter fluids such as liquids, gases, or mixtures thereof used in various industries. For example, the filter element/filter can be used to filter process fluids in the microelectronic industry for wet-etch cleans (e.g., a material removal process that uses liquid chemicals or etchants to remove materials from a wafer). CMP (chemical-mechanical planarization), for producing ultra pure water (UPW), and for lithography modules, and the fluids can include, for example, standard clean 1 (SCI) fluids, standard clean 2 (SC2) fluids, Isopropyl Alcohol (IP A; including hot IP A), Sulfuric Acid (H2SO4 including hot H2SO4), Tetramethyl quaternary ammonium hydroxide (TMAH; including hot TAMH), hydrogen peroxide (H2O2, including hot H2O2), Ammonium Hydroxide (NH4OH; including hot NH4OH), and Hydrogen Fluoride (HF; including hot HF), among others, used independently or mixed with each other. [0042] Typically, the pleated porous filter element comprises, or is, a membrane. The membranes can have any suitable pore structure, e.g., a pore size (for example, as evidenced by bubble point, or by KL as described in, for example, U.S. Patent 4,340,479, or evidenced by capillary condensation flow porometry), an average pore size; a mean flow pore (MFP) size (e.g., when characterized using a porometer, for example, a Porvair Porometer (Porvair pic, Norfolk, UK), or a porometer available under the trademark POROLUX (Porometer.com; Belgium)), a pore rating, a pore diameter (e.g., when characterized using the modified OSU F2 test as described in, for example, U.S. Patent 4,925,572), or removal rating media. The pore structure used depends on the size of the particles to be utilized, the composition of the fluid to be treated, and the desired effluent level of the treated fluid. In some aspects, the membrane has (depending on the application), an average pore size in the range of 10 nm to 150 nm.

[0043] The porous membrane can have any desired critical wetting surface tension (CWST, as defined in, for example, U.S. Patent 4,925,572). The CWST can be selected as is known in the art, e.g., as additionally disclosed in, for example, U.S. Patents 5,152,905, 5,443,743, 5,472,621, and 6,074,869. Typically, the membrane has a CWST of in the range of 28 dynes/cm (28 x 10' ⁵ N/cm) to 34 dynes/cm (34 x 10' ⁵ N/cm).

[0044] Exemplary membranes are disclosed in U.S. Patents 4,702,840 and 4,900,449. Other membranes, including those disclosed in U.S. Patents 4,906,374; 4,886,836; 4,964,989; 5,019,260; 4,340,479; 4,855,163; 4,744,132; 4,707,266; 4,203,848; 4,618,533, 6,039,872; 6,780,327; 6,783,937; and 7,189,322, may also be suitable. Exemplary membranes include, but are not limited to, nylon membranes, polytetrafluoroethylene (PTFE) membranes, high-density polyethylene (HDPE) membranes, and highly asymmetric polyarylsulfone (HAPAS) membranes. Exemplary' membranes may be used individually or in combination with any other exemplary membranes having the same or different characteristics.

[0045] The filter can include additional elements, layers, or components, that can have different structures and/or functions, e.g., at least one of any one or more of the following: prefiltration, support, drainage, spacing and cushioning.

[0046] For example, in the aspect of the filter 3100 as shown in Figure 3, in addition to a cylindrical perforated inner core 800 coaxially disposed along the inner periphery of the filter element and a cylindrical outer cage 900 disposed along the outer periphery of the filter element 3000, the illustrated filter includes a first pleated mesh 501 contacting a first (e.g., upstream) surface of the porous medium 500 of the filter element, and a second pleated mesh 502 contacting a second (e.g., downstream) surface of the porous medium 500 of the filter element, providing a three-layer composite. In those aspects wherein the filter includes first and/or second pleated meshes, references to contact between surfaces of the pleats refers to contact between the meshes on the referenced surfaces of the filter element, e.g., a second (inner) longitudinal counter-pleat leg surface of one longitudinal counter-pleat being in intimate contact with a second (inner) longitudinal counter-pleat leg surface of an adjoining leg of the one longitudinal counter-pleat, refers to the mesh on the second (inner) longitudinal counter-pleat leg surface of one longitudinal counter-pleat being in intimate contact with the mesh on a second (inner) longitudinal counter-pleat leg surface of an adjoining leg of the one longitudinal counter-pleat.

[0047] The components (meshes, filter medium) forming the filter element can be formed into a composite by conventional filter manufacturing techniques, either prior to or simultaneous with corrugation.

[0048] The meshes (the term “mesh” also includes “screen”) prevent opposing surfaces of the filter medium from coming into contact with one another and enables fluid to evenly flow to or from substantially all portions of the surface of the filter medium when the pleats are in the laid-over state. Thus, virtually the entire surface area of the filter medium may be effectively used for filtration.

[0049] A variety of meshes are suitable for use in aspects of the invention. The meshes can be made of any materials having suitable edgewise flow characteristics, i.e., suitable resistance to fluid flow through the layer in a direction parallel to its surface. The edgewise flow resistance of the drainage meshes is preferably low enough that the pressure drop in the drainage layer is less than the pressure drop across the filter medium, thereby providing an even distribution of fluid along the surface of the filter medium.

[0050] Typically, a filter 3100 according to an aspect of the present invention will be equipped with end caps 850 (only one of which is shown in Fig. 3) at one or both ends of the filter element 3000. The end caps 850 can be either blind (closed) or open end caps, and the material of which they are formed and their shape can be selected in accordance with the filtering conditions and the materials of the members to which the end caps are to be joined. Preferably, the end caps 850 are atached to the filter element 3000, but they may also be atached to the inner core 800 or the outer cage 900. Conventional techniques can be used to atach the end caps to the filter element.

[0051] If desired, in some aspects, an insert in the form of a strip of material having a good affinity for the end cap material can be corrugated into the ends of the filter element 3000 to improve the seal between both ends of the filter element 3000 and the end caps 850. For example, when the end caps are made of a fluoropolymer, a strip of another fluoropolymer, such as a fluorinated ethylene-propylene (FEP) resin, can be corrugated into the ends of the filter element as the insert. The insert need only be wide enough to bond the filter medium to the end cap, and therefore, it might extends for only a portion of the axial length of the filter element 3000. A typical width for the insert is approximately 0.5 inches.

[0052] Aspects of the filter device and filter are suitable for outside-m flow in which a fluid to be filtered flows from an outer periphery (e.g., the outer cage) through the filter element into the hollow center (e.g., the inner core), or it can be used for inside-out flow in which fluid flows from the hollow center (e.g., the inner core) through the filter element to the outer periphery (e.g., the outer cage).

[0053] The filter element 3000 illustrated in Figure 3 can be manufactured by a variety of techniques, for example, as described in U.S. Patent 5,543,047.

[0054] Tn one technique, the filter composite is first corrugated to form a corrugated sheet, cut to a suitable length or suitable number of pleats, and then formed into a cylindrical shape. The lengthwise edges of the corrugated sheet are then sealed to each other by conventional means to form a cylindrical filter element. The pleats of the filter element are then laid over as the filter element 3000 is inserted into a cage 900. After the filter element has been fit into the cage 900, a core 800 is inserted into the hollow center of the filter element 10, and then end caps are atached to the ends of the filter element to form a completed filter.

[0055] The filter comprising the filter element is disposed in a housing comprising at least one inlet and at least one outlet and defining at least one fluid flow path between the inlet and the outlet, wherein the filter is across the fluid flow path, to provide a filter device. Preferably, the filter device is sterilizable. Any housing of suitable shape and providing at least one inlet and at least one outlet may be employed.

[0056] The housing can be fabricated from any suitable rigid impervious material, including any impervious thermoplastic material, which is compatible with the fluid being processed. For example, the housing can be fabricated from a metal, such as stainless steel, or from a polymer. In a preferred aspect, the housing is a polymer, in some aspects, a transparent or translucent polymer, such as an acrylic, polypropylene, polystyrene, or a poly carbonated resin.

[0057] The following example further illustrates the invention but, of course, should not be construed as in any way limiting its scope.

EXAMPLE

[0058] This example demonstrates an improvement in permeability of a test filter device containing a filter element according to an aspect of the invention compared to a test filter device including a commercial available filter element that has laid-over longitudinal pleats (as generally described in U.S. Patent 5,543,047).

[0059] A filter is produced as generally shown in Figure 3 (the filter element having the configuration generally shown in Figures 1 and 2; Figure 2 also shows a seal between the ends of the filter element). The filter element, a PTFE membrane having a pore size of 80 nm, is pleated (with upstream and downstream meshes) using a Rabofsky PM600 corrugator.

[0060] The filter has 156 filter element groups, each filter element group having a forward filter element group comprising a first forward bridge, first, second and third longitudinal counter-pleats, a rear filter element group comprising a first rear bridge, and first, second and third longitudinal pleats, wherein no bridge or pleat height is repeated. Each bridge and pleat height differs from the other heights by at least 5%.

[0061] The commercially available filter element (PTFE membrane) has longitudinal pleat heights of 1 inch.

[0062] The filter element according to an aspect of the invention and the commercially available filter element have the same perforated inner cores and outer cages, and the same gap width of .85 inches. Each filter element has an open end cap at one end and a closed end cap at the other end, and are placed in a test housing arranged for outside-in flow.

[0063] The test device with the filter element according to an aspect of the invention has a 15% lower pressure drop but at a lower membrane area than the test device with the commercially available filter element. Thus, the permeability (flow per unit area per unit pressure drop) of the filter elements according to an aspect of the invention show an enhancement of at least 20%.

[0064] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0065] The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. [0066] Preferred aspects of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred aspects may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.