Curved core for variable pleat filter

Abstract

To provide a cylindrical filter element having a pleated configuration, using an existing outer filter geometric shape, to increase the amount of usable or "unmasked" filter material within a given filtration space.SOLUTION: A cylindrical filter element includes a central longitudinal axis extending along a height of the filter element, a core element extending along at least a portion of the height of the filter element and having a convex curved central portion extending from a first end to a second end to define a width of the core element, in which the convex curved central portion has a maximum height through the central longitudinal axis that is larger than a height of at least one of the first and second ends, and a filter material including a plurality of pleats extending radially from an outer periphery of the core element, in which an outer cylindrical periphery of the filter material is defined by an outer pleat tip of each of the plurality of radially extending pleats, and in which an inner pleat tip of each radially extending pleat is adjacent to the core element.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62 / 853,935, filed May 29, 2019, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to filters, and more particularly to pleated filtration material disposed about a longitudinally extending core element having an elongated oval or elliptical cross-section. [Background technology]

[0003] Fluid filters are commonly used to remove contaminants from liquids or gases so as not to damage downstream components such as engines. Filtration systems are generally configured such that an incoming contaminated fluid moves along a flow path until it impinges on a filter material. As the fluid passes through the filter material, a significant amount of the contaminants are captured by the filter material such that the resulting fluid exits the filter such that the resulting fluid is deemed sufficiently clean for a particular use.

[0004] A wide range of filter configurations are available for use in various applications. In a relatively simple configuration, a single flat sheet of filter material is positioned in the flow path such that contaminated fluid flows from the "dirty" side to the "clean" side of the filter material, the flat filter sheet being of a specific design that captures contaminants of a certain size and / or composition. To provide additional filtering performance, the filter material is commonly pleated to increase the amount of filter material used in a given space. Specifically, the filter material can be folded in an accordion-like fashion to create multiple pleats across the width of the material. The pleats for these configurations typically include pleats of the same or similar height across the width of the media pack.

[0005] To fit a particular opening and / or to further increase the amount of filter material provided in a given volume, the pleated filter material may also be arranged in a cylindrical configuration with the pleats extending radially from a central core area, etc. The core may be circular or may have a rectangular cross-sectional shape, for example. In either case, the pleats are relatively densely packed in the area closest to the central core, thereby "covering" the filter material and rendering it unusable. Summary of the Invention [Problem to be solved by the invention]

[0006] While the above configurations may be suitable for many filtration applications, there is a need to provide a pleat configuration that uses existing outer filter geometries while increasing the amount of usable, i.e., "uncoated," filter material within a given filtration space. [Means for solving the problem]

[0007] According to embodiments described herein, a cylindrical filter element is provided that includes a central longitudinal axis extending along a height of the filter element, a core element extending along at least a portion of the height of the filter element, and a filter material. The core element includes a convexly curved central portion extending from a first end to a second end to define a width of the core element, the convexly curved central portion having a maximum height through the central longitudinal axis that is greater than a height of at least one of the first and second ends. The filter material includes a plurality of pleats extending radially from an outer periphery of the core element, the cylindrical periphery of the filter material being defined by an outer pleat tip of each of the plurality of radially extending pleats, and an inner pleat tip of each of the radially extending pleats being adjacent to the core element.

[0008] In cylindrical filter element embodiments, the first and second ends of the core element have the same height. At least one internal pleat tip may be adjacent one of the first and second ends of the central portion of the core element. The area adjacent at least one of the first and second ends may be free of any radially extending pleats such that the area is free of filter material.

[0009] The core element may include wings extending from at least one of the first and second ends, with at least one of the wings having a height greater than a height of at least one of the first and second ends. The core element is symmetric about a central longitudinal axis. The core element may be symmetric or asymmetric about the central longitudinal axis, and in embodiments may be offset from the axis. The convexly curved center of the core element may be generally constantly tapered from an area adjacent the central longitudinal axis to at least one of the first and second ends.

[0010] The pleat depth of the plurality of pleats can vary across the width of the core element such that each pleat increases in depth from the first end toward the central longitudinal axis and then decreases in depth from the pleat adjacent the central longitudinal axis toward the second end.

[0011] The present invention will be further described with reference to the accompanying drawings, in which like elements are designated by like numerals throughout the several views. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a plan view of an embodiment of a filter with an internal pleat spaced central core configuration according to the filters described herein. [Diagram 2] 2 is a perspective view of an embodiment of a central core configured for use in a filter of the type shown in FIG. 1, for example. [Diagram 3] FIG. 3 is a plan view of the central core of FIG. 2. [Figure 4] FIG. 13 is a plan view of another embodiment of a filter according to the present disclosure with a central core configuration with spaced apart internal pleats. [Diagram 5] FIG. 2 is a plan view of an embodiment of a filter with an internal pleat spaced central core configuration according to the filters described herein. [Figure 6] 6 is a perspective view of an embodiment of a central core configured for use in a filter of the type shown in FIG. 5, for example. [Figure 7] FIG. 7 is a plan view of the central core of FIG. 6. [Figure 8] FIG. 2 is a plan view of an embodiment of a filter with an internal pleat spaced central core configuration according to the filters described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Turning now to the figures, in which components are numbered the same throughout the several views, and initially to FIG. 1, a plan view of an embodiment of a cylindrical filter 10 is shown. Filter 10 includes a central core 12 that extends along at least a portion of the height of filter 10. Filter 10 further includes a pleated filter material 14 disposed about central core 12 and extending generally radially outward from core 12. As shown, filter 10 has a peripheral boundary represented by a circle 16, which may be provided by a shell extending along at least a portion of the filter height, a filter cap at one or both ends of the filter material, and / or another structure. In either case, peripheral boundary 16 is generally circular and can optionally be designed to fit into existing applications utilizing a filter of a particular size and shape, or can be designed for a new application.

[0014] 2 and 3 show an exemplary embodiment of a central core 12 that can be used in the filter embodiment of FIG. 1. As shown, the ends or apex of the central core 12 have an elongated shape including a convexly curved central portion 18 and first and second ends 20, 22. The core 12 may be centered about a central longitudinal axis 24 or may be at least slightly offset from the central axis 24. The core 12 may be further symmetrical about the central axis 24 as shown, or the two portions on opposite sides of the central axis 24 may have shapes that are at least slightly different from each other. However, in the filter 10 shown, the core 12 is symmetrical about the central axis 24. In this embodiment, the first and second ends 20, 22 have the same width 28, which is less than the maximum width 26 of the curved central portion 18. However, the ends 20, 22 may instead have widths that are at least slightly different from each other.

[0015] The curvature of the central portion 18 of the core 12 is generally constant such that the width of the core 12 tapers generally constantly from a width 26 at the central area of ​​the core to a width 28 at the first and second ends 20, 22. However, it is understood that the curvature of the central portion 18 can instead vary such that the radius of curvature varies over the length of the core 12. In each case, the ends 20, 22 are shown generally flat, with the end faces generally perpendicular to the length of the core, although the end faces could be of different configurations, such as curved, angled, etc.

[0016] 2 and 3 show one exemplary structural configuration for the central core 12 along its height, which includes multiple support structures. The configuration of the support structures can vary considerably, but should be selected to provide sufficient structural integrity to the core while allowing the desired flow rate through the core during filtration (i.e., designed to not significantly block the flow of material). The support structures shown extend both longitudinally and laterally with spaces that provide the desired filtration performance. The relative number of support structures can be higher or lower than shown. In any configuration, however, the periphery of the core should have a surface that provides a structure against which the pleat tips of the filter material can be supported.

[0017] In embodiments of the present invention, a single central core 12 extends along the entire height of the cylindrical filter 10. In other embodiments, the core 12 extends along only a portion of the height of the cylindrical filter 10. In configurations in which the core 12 extends along only a portion of the height of the filter 10, multiple cores 12 can be "stacked" together along the height of the filter 10, with or without spaces between them.

[0018] 1, the filter material 14 is pleated and positioned in the space between the central core 12 and the peripheral boundary 16 of the filter 10. The fold or tip located closest to the central core 12 is referred to herein as the inner tip, while the fold or tip located closest to the peripheral boundary 16 is referred to as the outer tip. Because the outer shape of the core 12 and the shape of the peripheral boundary 16 are different, the space between them varies around the circumference of the filter, and thus the pleated filter material 14 has pleats of varying lengths around the filter 10. That is, the area nearest the first and second ends 20, 22 of the core 12 is smaller than the area adjacent the curved center 18. This oval cross-sectional shape of the central core 12 helps to naturally space the pleats from one another around the circumference of the filter 10, while allowing more media to fit into the space with a central core that is circular. This is due to the geometry of a circular central core, where the inner tips adjacent the core are spaced with a desired spacing between them, resulting in the outer tips being spaced relatively large from one another, thereby not maximizing the amount of filter material that can fit into the available space.

[0019] The pleated filter material can be selected from a number of different materials, such as a sheet of nonwoven material (e.g., a meltblown material) or a microporous membrane (e.g., nylon, poly(tetrafluoroethylene) (PTFE), polypropylene, polyethylene, etc.). The pleated filter material can be provided as a sheet that can be folded multiple times to create the desired pattern, and thus has a thickness that allows it to fold back on itself and maintain the folded pattern.

[0020] As used herein, the term "pleat" generally refers to a V-shaped configuration of filter material that includes two adjacent arms with a distal end that meets the circumference of a cylindrical filter at an "apex." Each of the arms also includes a proximal end that is spaced radially inward from the circumference to define a portion of the interior V-shaped configuration of the filter circumference at a "valley." Additionally, although a V-shape is described, the tip or point of the V-shape can be at least slightly rounded along the thickness of the filter material, with the tip radius being a function of the pleating method and tooling used.

[0021] To provide a particular amount of filter material 14 for a particular filter, the parameters of the central core 12 can be designed and adjusted accordingly. That is, the dimensions of the core can be selected to provide a cross section that is more oval, circular, or rectangular than that shown. As another example of such a central core shape, FIG. 4 provides a filter 110 with a central core 112 having first and second ends 120, 122 that is rounder and has an overall more "flat" shape than the central core 12 of FIGS. 1-3. Thus, the filter material 114 is positioned such that its inner tip is adjacent to the central core 112 along its longitudinally curved surface, but there is no inner tip located directly adjacent to the tips of the first and second ends 120, 122. That is, the pleats in this embodiment do not extend radially outward from the tips of the first and second ends 120, 122 toward the peripheral boundary 116 of the filter 110. Thus, there is no corresponding outer tip of the filter material spaced radially from the tips of the first and second ends 120, 122.

[0022] 5-7, a plan view of another embodiment of a cylindrical filter 210 is shown. Filter 210 includes a central core 212 that extends along at least a portion of the height of filter 210. Filter 210 further includes pleated filter material 214 disposed about central core 212 and extending generally vertically outward from core 212, the term "vertically" being used with reference to the orientation of filter 210 in FIG. 5. As shown, filter 210 has a peripheral boundary represented by a circle 216, which may be provided by a shell extending along at least a portion of the filter height, a filter cap at one or both ends of the filter material, and / or other structure. In either case, peripheral boundary 216 is generally circular and is designed or selected to fit new applications as well as existing applications that utilize filters of this size and shape.

[0023] 6 and 7 show an exemplary embodiment of a central core 212 that can be used in the filter embodiment of FIG. 5. As shown, the ends or tops of the central core 212 have an elongated shape including a convexly curved central portion 218 with first and second ends 220, 222 along with wings 230, 232 extending from each of the first and second ends 220, 222. The core 212 may be centered about a central longitudinal axis 224 or may be at least slightly offset from the axis 224. The core 212 may further be symmetrical about the central axis 224 as shown, or the two core portions on opposite sides of the axis 224 may have shapes that are at least slightly different from each other. However, in the filter 210 shown, the core 212 is symmetrical about the central axis 224. In this embodiment, the first and second ends 220, 222 have the same width 228, which is less than the maximum width 226 of the curved central portion 218. Wing portions 230, 232 have a width 227 shown to be greater than width 226 of central portion 216 and width 228 of first and second ends 220, 222, although it is understood that width 228 can be less than width 226 of central portion 216 and / or width 228 of first and second ends 220, 222.

[0024] The curvature of the center portion 218 of the core 212 is generally constant such that the width of the core 212 tapers generally constantly from a width 226 at the center of the core to a width 228 at the first and second ends 220, 222. However, it is understood that the curvature of the center portion 218 can instead vary such that the radius of curvature varies over the length of the core 212. In each case, the ends 220, 222 are shown generally flat, and the end faces are generally perpendicular to the length of the core, although the end faces can be of different configurations, such as curved, angled, etc. The wings 230, 232 are shown as relatively thin, elongated members that are the same size and shape. However, these wings 230, 232 can instead have different shapes and relative sizes than shown, and can have different configurations (e.g., shapes, sizes, etc.) from one another.

[0025] 6 and 7 show one exemplary embodiment of support structures for the central core 212. The configuration of the vertically and horizontally arranged support structures can vary considerably, but the configuration should be selected to provide sufficient structural integrity to the core while allowing the desired flow rate through the core during filtration. The support structures shown extend both longitudinally and laterally and are spaced apart to provide the desired performance. The relative number of support structures can be higher or lower than shown. In any configuration, however, the periphery of the core 212 should have a surface that provides a structure against which the pleat tips of the filter material 214 can be supported.

[0026] In this embodiment, the filter material 214 is positioned such that its interior extremities are adjacent the central core 212 along its longitudinally curved surface, but does not have interior extremities positioned adjacent the first and second ends 220, 222, or the wings 230, 232. That is, the pleats in this embodiment do not extend radially outward from the first and second ends 220, 222, or the wings 230, 232, toward the peripheral boundary 216 of the filter 210. Instead, the filter 214 generally follows the outer contours of each of the wings 230, 232, as shown.

[0027] 8, a plan view of another embodiment of a cylindrical filter 310 is shown. Filter 310 includes a central core 312 that extends along at least a portion of the height of filter 310. Filter 310 further includes a pleated filter material 314 disposed about central core 312. As shown, filter 310 has a peripheral boundary represented by a circle 316, which may be provided by a shell that extends along at least a portion of the filter height, a filter cap at one or both ends of the filter material, and / or another structure. In either case, peripheral boundary 316 is generally circular and can be designed or selected to fit new applications as well as existing applications that utilize filters of this size and shape.

[0028] In this embodiment, the end or top of the central core 312 has an elongated shape including a convexly curved central portion 318 with first and second ends 320, 322 along with two extensions 330, 332 extending from the first and second ends 320, 322, respectively. The core 312 may be centered about a central longitudinal axis 324 or may be at least slightly offset from the axis 324. The core 312 may also be symmetrical about the central axis 324 as shown, or the two core portions on opposite sides of the axis 324 may have shapes that are at least slightly different from each other. However, in the filter 310 shown, the core 312 is symmetrical about the central axis 324. In this embodiment, the first and second ends 320, 322 have the same width, which is less than the maximum width of the curved central portion 318. The extensions 330, 332 can have a length such that their tips extend beyond the outer width of the central portion 316 and the width of the first and second ends 320, 322, although it is understood that the tips can extend a distance less than the width of the central portion 316 and / or the width of the first and second ends 320, 322.

[0029] The curvature of the center portion 318 of the core 312 is generally constant such that the width of the core 312 tapers generally constantly from the width at the center of the core to the width at the first and second ends 320, 322. However, it is understood that the curvature of the center portion 318 can instead vary such that the radius of curvature varies over the length of the core 312. The extensions 330, 332 are shown as relatively pointed members that are the same size and shape. However, these extensions 330, 332 can instead have different shapes and relative sizes than shown, and can have different configurations (e.g., shapes, sizes, etc.) from one another.

[0030] In this embodiment, the filter material 314 is positioned such that its interior extremities are adjacent the central core 312 along its longitudinally curved surface, but does not have interior extremities positioned adjacent the first and second ends 320, 322 or the extensions 330, 332. That is, the pleats in this embodiment do not extend directly radially outward from the edges of the first and second ends 320, 322 in a direction generally perpendicular to the width of the curved central portion 318. Instead, the pleats in the areas of the extensions 330, 332 generally surround the shape of the extensions 330, 332 and extend toward the peripheral boundary 316 of the filter 310. That is, the filter material 314 generally follows the outer contours of each of the extensions 330, 332 as shown.

[0031] In the embodiments of the central cores shown and described herein, each core is defined at least in part by an outer curved surface at its center. This outer curved surface generally has a flatter radial curvature than the radial curvature of the peripheral boundary of the cylindrical filter. In this way, the core is more "flat" in shape compared to the greater curvature of the peripheral boundary of the filter. For example, the central core can be elliptical, while the peripheral boundary can be circular or cylindrical, as described herein with respect to the exemplary embodiments of the filter element of the present invention.

[0032] In an aspect of the invention, a cylindrical filter element includes a central longitudinal axis extending along a height of the filter element; a core element extending along at least a portion of the height of the filter element, the core element including a convexly curved central portion extending from a first end to a second end to define a width of the core element, the convexly curved central portion including a maximum height through the central longitudinal axis that is greater than a height of at least one of the first and second ends; and a filter material including a plurality of pleats extending radially from an outer periphery of the core element, the cylindrical periphery of the filter material being defined by an outer pleat tip of each of the plurality of radially extending pleats, and an inner pleat tip of each of the radially extending pleats being adjacent the core element.

[0033] In this cylindrical filter element, any or all of the following aspects may be met: the first and second ends of the core element have the same height; at least one internal pleat tip is adjacent one of the first and second ends of the central portion of the core element; the area adjacent at least one of the first and second ends does not include any radially extending pleats; the core element further includes wings extending from at least one of the first and second ends, at least one of the wings having a height greater than a height of at least one of the first and second ends. The pleat depth of the plurality of pleats may vary across the width of the core element such that each pleat increases in depth from the first end in a direction toward the central longitudinal axis and then decreases in depth from the pleat adjacent the central longitudinal axis in a direction toward the second end, the core element may be symmetric or asymmetric about the central longitudinal axis, the core element may be offset from the central longitudinal axis, and / or a convexly curved central portion of the core element may be provided that tapers generally constantly from an area adjacent the central longitudinal axis to at least one of the first and second ends.

[0034] The present invention is described herein with reference to some of its embodiments. The entire disclosure of any patent or patent application identified herein is incorporated herein by reference. The above detailed description and examples are given merely for ease of understanding. No unnecessary limitations should be understood therefrom. It will be apparent to those skilled in the art that many modifications can be made to the described embodiments without departing from the scope of the present invention. Thus, the scope of the present invention should be limited only by the structures described by the language of the claims and the equivalents of those structures, rather than by the structures described herein.

Claims

1. a central longitudinal axis extending along the height of the filter element; a core element extending along at least a portion of a height of the filter element, the core element including a convexly curved central portion extending from a first end to a second end to define a width of the core element, the convexly curved central portion including a maximum height through the central longitudinal axis that is greater than a height of at least one of the first and second ends; a filter material including a plurality of pleats extending radially from an outer periphery of the core element, a cylindrical periphery of the filter material being defined by an outer pleat tip of each of the plurality of radially extending pleats, and an inner pleat tip of each of the radially extending pleats being adjacent to the core element.

2. The cylindrical filter element of claim 1 , wherein the first and second ends of the core element have the same height.

3. 3. The cylindrical filter element of claim 1 or 2, wherein at least one internal pleat tip is adjacent one of the first and second ends of the central portion of the core element.

4. The cylindrical filter element of any one of claims 1 to 3, wherein an area adjacent at least one of the first and second ends does not include any radially extending pleats.

5. 5. The cylindrical filter element of claim 1, wherein the core element further comprises a wing extending from at least one of the first and second ends, at least one of the wing comprising a height greater than a height of at least one of the first and second ends.

6. 6. The cylindrical filter element of claim 1, wherein a pleat depth of the plurality of pleats varies across the width of the core element such that each pleat increases in depth from the first end toward the central longitudinal axis and then decreases in depth from a pleat adjacent the central longitudinal axis toward the second end.

7. The cylindrical filter element of any one of claims 1 to 6, wherein the core element is symmetric about the central longitudinal axis.

8. The cylindrical filter element of any one of claims 1 to 7, wherein the core element is asymmetric about the central longitudinal axis.

9. The cylindrical filter element of any one of claims 1 to 8, wherein the core element is offset from the central longitudinal axis.

10. 10. The cylindrical filter element of claim 1, wherein the convexly curved central portion of the core element tapers generally constantly from an area adjacent the central longitudinal axis to at least one of the first and second ends.

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