Filter and method of filtering a fluid

Abstract

A filter including alternating layers of filter medium and diffusion medium. The filter provides optimum distribution of fluid over the filtering medium, a reduced pressure drop and an increased filter life, without a reduction in filter rating. The diffusion medium has a first plane of spaced-apart, substantially parallel strands defining first longitudinal passages having a first height dimension and a first width dimension, and a second plane of spaced-apart, substantially parallel strands defining second longitudinal passages having a second height dimension and a second width dimension. The strands of the second plane of the diffusion medium are oriented in a non-parallel manner with respect to the strands of the first plane, such that the first and the second planes define lateral openings having side dimensions. The first and the second longitudinal passages include at least one dimension that is smaller than any of the side dimensions of the lateral openings. At least a portion of the layers of filter medium have bypass apertures, wherein such portion defines at least one pre-qualifying filter medium layer.

Description

[0001] The present application claims priority to U.S. provisional patent application Ser. No. 60 / 103,233, filed Oct. 5, 1998, the disclosure of which is incorporated herein by reference.BACKGROUND OF THE DISCLOSURE

[0002] 1. Technical Field

[0003] The present disclosure relates, in general, to a filter, a method of making a filter and a method of filtering a fluid.

[0004] More particularly, the present disclosure relates to a filter having alternating layers of non-filtering diffusion medium and filter medium. Some of the layers of the filter medium are provided with bypass apertures, while the remaining layers do not include bypass apertures so that they act as qualifying layers for the filter. Filters according to the present disclosure have been found to provide improved fluid distribution over the filter medium, reduced pressure drop and increased filter life, without a reduction in filter rating.

[0005] 2. Discussion of Background Disclosures

[0006] In general, a filter assembly is...

Examples

example ii

[0065]

[0066] Referring to FIG. 8, a second example of a filter 50 according to the present disclosure is shown. The filter 50 includes a single continuous sheet of diffusion medium 20 comprising thirty thousandths of an inch (30 mils), bi-planar strand orientation (17 mil strand size), twelve strands per inch, polypropylene extruded netting. The Side-to-Height Ratio of the diffusion medium 20 is approximately 4:1. The filter material, which comprises melt-blown, non woven polypropylene micro fibers, is provided in a plurality of discrete sheets 16a, 16b, 16c, 16d.

[0067] The sheets of filter medium 16a, 16b, 16c exhibit substantially equal and consistent pore size and fiber geometry. Sheet 16a does not have bypass apertures, while outer sheets 16b, 16c have bypass apertures 18. The outermost sheet 16c of filter material is preferably provided with more numerous bypass apertures 18 than the intermediate sheets 16b. Most preferably, the sheets 16b, 16c are perforated in a manner substa...

example iii

[0070]

[0071] Referring to FIG. 9, another filter cartridge 70 according to the present disclosure is shown. The filter cartridge 70 is similar to the filter cartridge 10 of FIG. 7, and elements that are the same have the same reference numerals. The filter cartridge 70 includes a filter 72 having alternating layers of filter medium 74 and diffusion medium 76.

[0072] The filter medium 74 has bypass apertures formed from bores 78 extending from an outermost layer 80 towards an innermost layer 82 of the filter. The continuous bores 78 each extend to a uniform depth within the filter 72. Preferably, the bores 78 extend continuously to between about fifty and eighty-five percent (50%-85%) of the radial distance from the outermost layer 80 to the innermost layer 82 of the filter 72. More preferably, each of the bypass bores 78 extends continuously to about sixty-six percent (66%) of such radial distance. It should be noted that the filter medium of the filter cartridge 70 can be provided w...

example iv

[0074]

[0075] Referring to FIG. 10, a further filter cartridge 110 according to the present disclosure is shown (filter cartridge 110 is not shown with end caps; as will be readily apparent to persons of skill in the art). The filter cartridge 110 is similar to the filter cartridge 70 of FIG. 7, and elements that are the same have the same reference numerals. The filter cartridge 110 includes a filter having a single continuous sheet of diffusion medium 20 and at least one sheet of filter medium 16a wound around a core 12. The filter 110 also includes strips of filter medium 114 wound within the sheet of diffusion medium 20 between the sheet of filter medium 14 and the outer diameter of the filter. The strips 114 are spaced apart to create gaps that comprise bypass apertures 116.

[0076] As shown, the strips of filter medium 114 are arranged longitudinally with respect to the core 12, but the strips can be oriented in other directions, such as diagonally with respect to the core. The s...

[0001] The present application claims priority to U.S. provisional patent application Ser. No. 60 / 103,233, filed Oct. 5, 1998, the disclosure of which is incorporated herein by reference.BACKGROUND OF THE DISCLOSURE

[0002] 1. Technical Field

[0003] The present disclosure relates, in general, to a filter, a method of making a filter and a method of filtering a fluid.

[0004] More particularly, the present disclosure relates to a filter having alternating layers of non-filtering diffusion medium and filter medium. Some of the layers of the filter medium are provided with bypass apertures, while the remaining layers do not include bypass apertures so that they act as qualifying layers for the filter. Filters according to the present disclosure have been found to provide improved fluid distribution over the filter medium, reduced pressure drop and increased filter life, without a reduction in filter rating.

[0005] 2. Discussion of Background Disclosures

[0006] In general, a filter assembly is...

Examples

example ii

[0065]

[0066] Referring to FIG. 8, a second example of a filter 50 according to the present disclosure is shown. The filter 50 includes a single continuous sheet of diffusion medium 20 comprising thirty thousandths of an inch (30 mils), bi-planar strand orientation (17 mil strand size), twelve strands per inch, polypropylene extruded netting. The Side-to-Height Ratio of the diffusion medium 20 is approximately 4:1. The filter material, which comprises melt-blown, non woven polypropylene micro fibers, is provided in a plurality of discrete sheets 16a, 16b, 16c, 16d.

[0067] The sheets of filter medium 16a, 16b, 16c exhibit substantially equal and consistent pore size and fiber geometry. Sheet 16a does not have bypass apertures, while outer sheets 16b, 16c have bypass apertures 18. The outermost sheet 16c of filter material is preferably provided with more numerous bypass apertures 18 than the intermediate sheets 16b. Most preferably, the sheets 16b, 16c are perforated in a manner substa...

example iii

[0070]

[0071] Referring to FIG. 9, another filter cartridge 70 according to the present disclosure is shown. The filter cartridge 70 is similar to the filter cartridge 10 of FIG. 7, and elements that are the same have the same reference numerals. The filter cartridge 70 includes a filter 72 having alternating layers of filter medium 74 and diffusion medium 76.

[0072] The filter medium 74 has bypass apertures formed from bores 78 extending from an outermost layer 80 towards an innermost layer 82 of the filter. The continuous bores 78 each extend to a uniform depth within the filter 72. Preferably, the bores 78 extend continuously to between about fifty and eighty-five percent (50%-85%) of the radial distance from the outermost layer 80 to the innermost layer 82 of the filter 72. More preferably, each of the bypass bores 78 extends continuously to about sixty-six percent (66%) of such radial distance. It should be noted that the filter medium of the filter cartridge 70 can be provided w...

example iv

[0074]

[0075] Referring to FIG. 10, a further filter cartridge 110 according to the present disclosure is shown (filter cartridge 110 is not shown with end caps; as will be readily apparent to persons of skill in the art). The filter cartridge 110 is similar to the filter cartridge 70 of FIG. 7, and elements that are the same have the same reference numerals. The filter cartridge 110 includes a filter having a single continuous sheet of diffusion medium 20 and at least one sheet of filter medium 16a wound around a core 12. The filter 110 also includes strips of filter medium 114 wound within the sheet of diffusion medium 20 between the sheet of filter medium 14 and the outer diameter of the filter. The strips 114 are spaced apart to create gaps that comprise bypass apertures 116.

[0076] As shown, the strips of filter medium 114 are arranged longitudinally with respect to the core 12, but the strips can be oriented in other directions, such as diagonally with respect to the core. The s...

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