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...

AI Technical Summary

Benefits of technology

0031] The longitudinal passages 28, 32 of the diffusion medium 20 distribute the fluid to be filtered through flow channels f1, f2, such that the diffusion medium 20 allows for, and assists in, the longitudinal, or circumferential and / or axial, flow of the contaminated fluid within the filter 14 between the innermost layer of the filter medium 16 and the core 12, and / or between adjacent layers of the filter medium. Such longitudinal flow assists in minimizing the pressure drop across the filter cartridge 10 and in dispersing the filtration function. The diffusion medium 20 is preferably positioned between the core 12 and the innermost layer of the filter medium 16 to facilitate the passage of fluid through the openings 36 in the core 12. In a preferred embodiment, the core 12 is surrounded by a plurality of diffusion medium 20 layers to provide a collection area for the flow prior to exiting through openings in the core 12. Positioning of the diffusion medium 20 between adjacent layers of the filter medium 16 similarly maximizes the use of the filter medium surface area within each layer for contaminant loading, thereby reducing pressure drop and optimizing filter medium usage to extend filter life.

0032] In preferred embodiments, the dimensions of the lateral openings 34 and the longitudinal passages 28, 32 of the diffusion medium 20 are purposely selected to be substantially larger than any contaminant to be filtered from the contaminated fluid. As a result, the diffusion medium 20 does not act as a filter. Since the diffusion medium 20 does not act, and is not used, as a filter to trap contaminants, the diffusion medium does not substantially contribute to the pressure drop across the filter 14, and in fact minimizes the pressure drop by providing unobstructed flow channels f1, f2 for contaminated fluid. In addition, the diffusion medium 20 provides structural rigidity and protects the filter medium 16 from damage. The filter 14 is advantageously provided with an extra outer layer of the diffusion medium 20 to add support and protection to the filter 14.

Problems solved by technology

When a depth filter cartridge mimics a surface filter and collects contaminants in primarily one layer, the results are an inefficient distribution of fluid over the filter medium, a higher pressure drop for fluid passing through the filter and a lower flow rate capability for the filter.

Such filters also tend to have a shorter useful life, and thus must be replaced more often.

The Drori filter elements fail to optimally enhance fluid flow while providing extended filter service life.

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