Fluid filtration device, system and method

Abstract

A filter is disclosed, the filter comprising: a first flow face, the first flow face extending along the lateral direction and the transverse direction of the filter, wherein the first flow face comprises at least one first edge of a contaminant retention layer and at least one first edge of a flow defining layer; a second flow face, the second flow face being spaced apart from the first flow face in the axial direction, wherein the second flow face extends along the length and width of the filter and comprises at least one second edge of a contaminant retention layer and at least one second edge of a flow defining layer; at least one contaminant retention layer, the at least one contaminant retention layer extending from the first edge of the contaminant layer to the second edge of the contaminant layer; and at least one flow defining layer, the at least one flow defining layer being adjacent to at least one of the contaminant retention layers, the at least one flow defining layer extending from the first edge of the flow defining layer to the second edge of the flow defining layer, wherein, when the fluid moves from the first flow face toward the second flow face, at least one of the flow defining layers defines at least one fluid flow path in the axial direction.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62 / 543,456, filed on August 10, 2017, the entire contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention relates generally to filtration apparatus, systems and methods for filtering contaminants from fluids, and more particularly to filter arrangements that provide fluid movement oriented generally parallel to a face of the filter media. Background Art

[0004] For example, fluid flows of fuel, lubricants, or hydraulic oils often carry contaminant materials such as dust and other particulates into engines of construction equipment, diesel engines, and the like, such as particulate contaminants that may damage and / or negatively affect the performance of such equipment. In many cases, it is necessary and / or desirable to filter some or all of the incoming contaminant materials from the fluid flow to protect downstream components from damage by the contaminants. Many fluid filter arrangements have been developed for removing contaminants, which are often specifically designed to work in conjunction with a specific space within or near the equipment.

[0005] In certain filtering applications, a fluid moves along a fluid path and passes through relatively planar surfaces of one or more filter material sheets arranged in a stack in a housing. When multiple filter sheets are used, the sheets are usually arranged so that the generally planar surface of each sheet contacts the planar surface of an adjacent sheet. The filter sheets are designed or selected to correspond to the size and type of particles to be removed from the fluid. For example, the filter sheets selected for a particular filtering system typically include smaller holes than the particles expected to be captured when the fluid passes through the thickness of the filter sheets from one side to the other. Because the filter sheets are installed in such a way that they hinder the free flow of the fluid along the fluid path, the fluid pressure on the inlet side of the filter sheets will be higher than the fluid pressure after the fluid passes through the filter sheets. This concept is called the pressure difference or pressure drop across the filter sheets.

[0006] Over time, objects captured by the filter during its use will block or "load" an increasing number of the holes in the filter sheet, resulting in an increased pressure drop across the filter. The pressure drop will eventually reach an unacceptable level, after which the filter material will need to be cleaned or replaced to allow the device to continue to operate. Although it is expected that such filters will need to be cleaned and / or replaced periodically, it is desirable to increase the time between filter cleanings and / or replacements so that disruption to manufacturing or other operations is minimized. Therefore, there remains a need to provide a filtration system that effectively removes contaminants from a fluid while increasing the life of the filter, thereby avoiding problems such as premature fluid filter clogging. Summary of the invention

[0007] The filter system including the filter material arranged according to the present invention is referred to as the "flow-through" filter of the present invention, and the filter is constructed using at least two material layers arranged in a stacked or winding configuration, for example. These filters provide relatively constant removal efficiency for pollutants and / or particles of various types and sizes. The flow-through filter also can show reduced efficiency during pollutant loading, and the pressure difference changes very little during the entire loading process. However, the clean media pressure drop is relatively high. In conjunction with the performance characteristics of the flow-through filter as described herein, many possible application scenarios that can benefit from this filtering configuration are provided. It is expected that the filter of the present invention can be used to filter a variety of different substances, such as fuel, water, air, etc., and a variety of particulate and / or droplet pollutants can be captured.

[0008] In one aspect of the present invention, a filter is provided, the filter comprising: a first flow face extending along the lateral direction and the transverse direction of the filter, wherein the first flow face comprises at least one first edge of a contaminant retaining layer and at least one first edge of a flow defining layer; a second flow face spaced apart from the first flow face in the axial direction, wherein the second flow face extends along the length and width of the filter and comprises at least one second edge of a contaminant retaining layer and at least one second edge of a flow defining layer; at least one contaminant retaining layer extending from the first edge of the contaminant layer to the second edge of the contaminant layer; and at least one flow defining layer adjacent to at least one of the contaminant retaining layers, wherein the at least one flow defining layer extends from the first edge of the flow defining layer to the second edge of the flow defining layer. When the fluid moves from the first flow face toward the second flow face, at least one of the flow defining layers defines at least one fluid flow path in the axial direction.

[0009] In another aspect of the present invention, a method for filtering a fluid is provided, the method comprising the steps of positioning a filter in a fluid flow path, the filter comprising a first flow face extending along a length and a width of the filter, wherein the first flow face comprises at least one contaminant retention layer first edge and at least one flow defining layer first edge; a second flow face spaced apart from the first flow face in an axial direction, wherein the second flow face extends along the length and the width of the filter and comprises at least one contaminant retention layer second edge and at least one flow defining layer second edge; at least one contaminant retention layer extending from the first flow face to the second flow face; and at least one flow defining layer adjacent to at least one contaminant retention layer, the at least one flow defining layer extending from the first flow face to the second flow face, wherein the at least one flow defining layer causes material to flow in the axial direction when the fluid moves from the first flow face toward the second flow face. The method further comprises the step of moving the fluid along the fluid flow path, wherein the fluid flow path extends in the axial direction from the first flow face toward the second flow face. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention will be further explained with reference to the accompanying drawings, in which like structures in the several views are represented by like numerals, and in which:

[0011] Figure 1 is a schematic front view of a filter construction of the present invention, the filter construction comprising a plurality of contaminant retaining layers and a plurality of flow limiting layers;

[0012] Figure 2 is a perspective optical microscope view of an exemplary flow defining layer of the present invention;

[0013] Figure 3 is a top optical microscope view of an exemplary flow defining layer of the present invention;

[0014] Figure 4 is a graph of average initial efficiencies for certain contaminant sizes for various exemplary filter materials;

[0015] Figure 5 is a graph showing the effect of compression on the efficiency of three different exemplary sets of contaminant or particle retaining layers and flow defining layers;

[0016] Figure 6 is a graph comparing the efficiency of a standard flow-through filter arrangement to an exemplary flow-through filter arrangement of the present invention at various contaminant sizes;

[0017] Figure 7 is a graph showing the change in efficiency during a loading experiment for both an exemplary flow-through filter arrangement of the present invention and a standard or conventional flow-through filter arrangement;

[0018] Figure 8 is a graph showing the change in differential pressure during a loading experiment for both an exemplary flow-through filter arrangement of the present invention and a standard or conventional flow-through filter arrangement;

[0019] Fig. 9 is a perspective view of three exemplary flow-through filters of the present invention having different sizes;

[0020] Fig.10 is a graph illustrating the effect of pre-filter depth on its corresponding protective capacity for an exemplary flow-through filter of the present invention;

[0021] Fig.11 is a graph illustrating the effect of pre-filter depth on its corresponding contaminant removal efficiency for an exemplary flow-through filter of the present invention;

[0022] Fig.12 is a graph illustrating the effect of pre-filter depth on its corresponding initial differential pressure for an exemplary flow-through filter of the present invention;

[0023] Fig.13 is a top view of an exemplary stack of flow restricting layers and alternating contaminant retaining layers bonded along one edge in accordance with an embodiment of the present invention;

[0024] Fig.14 is a perspective view of an exemplary configuration of a flow defining layer and a contaminant retaining layer positioned adjacent to one another and rolled together in a coiled configuration;

[0025] Fig.15 is a perspective view of an exemplary configuration of a stack of flow restricting disks and alternating contaminant retaining disks arranged along a longitudinal axis;

[0026] Fig.16 is a schematic side view of another exemplary arrangement of a plurality of flow defining layers and contaminant retaining layers in a stacked arrangement; and

[0027] Fig.17 is a schematic side view of another exemplary arrangement of multiple flow defining layers and contaminant retaining layers in a stacked arrangement. DETAILED DESCRIPTION

[0028] Referring now to the drawings, wherein like numerals designate parts throughout the several views, and initially to Figure 1, showing a schematic diagram of a filter arrangement of the present invention. Such a filter arrangement is referred to herein as "flow-through" filtration because the contaminant-containing material flowing through the filter from the inlet flow face to the outlet flow face is generally oriented parallel to the planar surfaces (e.g., top and bottom surfaces) of the multi-layer filter media, such that the material flows "over" the surfaces of the filter media rather than through the surfaces of the filter media. This arrangement is generally perpendicular to conventional filter arrangements in which the fluid flows directly through the pore structure of the filter media (i.e., through the thickness of the filter media, such as from the top planar surface to the bottom planar surface).

[0029] In the flow-through filter construction of the present invention, multiple layers of material are arranged in a stack so that the edges of these layers are generally located in the same plane, which is referred to as a flow surface herein. Such a flow surface is therefore a surface defined by the edges of the layers, wherein this flow surface is generally perpendicular to the direction in which the material will flow relative to the stack, and is located at the position where the material enters and / or leaves the stack or construction of the filter material. Various variations of filter stacks or layers for forming various flow surfaces of the present invention are described herein. For example, as will be explained below, many embodiments of the flow surface will include the stacked edges of multiple layers, wherein all layer edges can be aligned with each other, or the flow surface can alternatively include an irregular surface consisting of the staggered edges of the layers, as will be discussed in more detail below.

[0030] Figure 1 A stack 10 of filter media is schematically shown, the stack including flow-limiting sheets or layers 12 alternating with contaminant or particle retaining sheets or layers 14 over the entire thickness of the stack. Although certain drawings and descriptions of the exemplary constructions provided herein show rectangular "sheets" of material, it should be understood that these sheets are representative and can therefore be provided as layers constructed in a variety of alternative ways. For one example, these layers can be provided as continuous lengths of material that are folded or otherwise arranged to have a construction that does not have all the specific edges provided by a single flat sheet. In another example, these layers can have different external shapes, such as circular, elliptical, triangular, trapezoidal, etc., as described in more detail below. In another example, these layers are more set to "areas" of permeability changes across the stack. In these or other constructions, it should be understood that the "flow-through" principle of the present invention can be applied in the same or similar manner as applicable to stacked sheets.

[0031] Each flow-defining layer 12 includes a first or top edge 16, a second or bottom edge 18 opposite the first edge 16, and side edges 20, 22 extending between the first edge 16 and the second edge 18. Each flow-defining layer 12 also includes a first face surface 24 and an opposite second face surface 26. The flow-defining layer 12 is used to define a flow path through the stack 10 of filter materials. Similarly, each contaminant retaining layer includes a first or top edge 30, a second or bottom edge 32 opposite the first edge 30, and side edges 34, 36 extending between the first edge 30 and the second edge 32 of the contaminant retaining layer 14. Each contaminant retaining layer 14 also includes a first face surface 38 and an opposite second face surface 40. Two different layers 12, 14 with different fiber constructions are used for their respective roles in the composite structure of the stack 10. That is, the flow-defining layer 12 performs the function of defining the flow path through the filter, while the contaminant retaining layer 14 performs the function of retaining or capturing contaminants (such as contaminants in a liquid) that are transported to its pore structure.

[0032] Although not required, in order to maximize the filtering performance of the filter stack of the present invention, the edges of the flow-restricting layer and the pollutant-retaining layer are usually aligned with each other in each stack. In certain embodiments, the stack will usually fill the housing or other structure in which it is located, so as to maximize the amount of material that can be used for filtering in a given volume. However, other embodiments may include layers of different sizes and / or shapes so that the edges of the various layers can be staggered along the height of the stack in an orderly or random arrangement. In any arrangement in which the edges of the layers are not aligned along a plane, the flow face will still include the edge of the layer facing the direction in which the material flow enters or leaves the filter stack.

[0033] The flow limiting layer 12 can be configured to have a mesh or screen type structure with relatively larger crossed fibers or strands than the fibers in the contaminant retaining layer. The relatively larger fibers and corresponding macropores of the flow limiting layer contribute to the composite flow permeability of the present invention. Although the flow-through filter of the present invention is configured so that the contaminated material generally flows across the surface of multiple layers, the size of the holes or openings is measured or sized transverse to the flow direction (i.e., the flow direction). That is, even if the filter is not arranged so that the material flows through the thickness of the filter material, the hole size is measured and selected to provide the desired flow characteristics.

[0034] Compared with the fibers in the flow limiting layer, the pollutant retaining layer 14 can be configured as a mesh or screen type structure with relatively small cross fibers or strands. The holes or openings produced by these crossed strands can be referred to as holes. The hole size is designed or selected in consideration of the size of the pollutants to be captured by the specific pollutant retaining layer. Alternatively, the pollutant retaining layer can be made of a material that does not have a mesh or screen type structure but still includes holes or openings, so as to allow flow, while the area around the opening can capture or block pollutants.

[0035] A common technique for measuring the pore size of either or both of the flow limiting layer and the contaminant retaining layer is the capillary flow porosimetry method. This technique uses capillary theory to calculate the pore size based on the relationship between the surface tension of the liquid, the pressure, and the diameter of each hole. This measurement method uses a non-reactive liquid to completely wet the pores of the porous material and fill it with a fluid with a very low contact angle with the material. Then, while measuring the pressure and air flow, the saturated material is pressurized with a non-reactive gas until all the liquid is forced to leave the pores. Using this technique, a smaller pore size will require a higher pressure to force the liquid to leave the pores, while the opposite is true for a larger pore size. The collected data is then compared with the pressure and flow measurements of the clean dry sample to calculate the pore size distribution. In this measurement, the mean flow pore size is defined at the point where the wet sample airflow is equal to half of the dry sample airflow.

[0036] Typically, for various embodiments of the present invention, the pore size of the flow-defining layer is greater than the size of the pores of the contaminant-retaining layer (also measured along the flow direction) when measured in the flow-through orientation using the above-described techniques and / or other techniques. In certain embodiments, the pore size of the contaminant-retaining layer is measured in the flow-through orientation from 1 to 200 microns, but more specifically may be in the range of 1 to 100 microns, more specifically in the range of 1 to 50 microns, more specifically 1 to 25 microns, more specifically 1 to 15 microns, or even more specifically 1 to 10 microns.

[0037] In one embodiment of the present invention, each flow limiting layer 12 is a single layer, wherein the structure is designed to guide the fluid to flow through the stack 10 mainly along the face of the contaminant retaining layer 14. The thickness, spacing and arrangement of the fibers or strands and the total thickness of the flow limiting layer can be varied in order to achieve the desired filtering performance. In an exemplary embodiment of the present invention, the total thickness of the flow limiting layer is in the range of about 200 μm to 5000 μm, more specifically in the range of 200 μm to 2000 μm, and more specifically in the range of 500 μm to 1000 μm, although the thickness can be less than or greater than these thickness ranges. When the flow limiting layer 12 is relatively thin, it provides greater resistance than when a thicker layer is used. On the other hand, when the flow limiting layer 12 is relatively thick, the capture efficiency of the composite filter structure may be relatively low. Therefore, when selecting the thickness of the flow limiting layer, the balance between resistance and capture efficiency can be considered.

[0038] Figure 2 and Figure 3 1 and 2 are perspective and top optical microscope views of an exemplary flow limiting layer 50 of the present invention, respectively. As shown, the flow limiting layer 50 includes spacers or spacer strands 52, the size, shape and strand density of which can vary. An exemplary embodiment includes, for example, spacers 52 having a thickness between 200 μm and 500 μm. When in a stack of layers, these spacers 52 will generally align with the flow direction. The ribbon strands 56 are arranged generally orthogonal to the spacers 52 and are much smaller than the larger strands 52. For example, the strands 56 can be approximately 100 μm.

[0039] The thickness of each flow defining layer is selected to provide the desired performance for the filter stack, since a flow defining layer that is too thin will provide too much resistance (low permeability), and a flow defining layer that is too thick will exhibit unacceptably low capture efficiency for a particular application. Therefore, it is desirable to select a flow defining layer that best matches the most important desired parameters for a particular filtration application.

[0040] Filter embodiments of the present invention can be provided with filter areas of different permeabilities in order to provide desired filter performance. In such embodiments, the permeability of the filter material will be measured from one flow face to another flow face, although the permeability can vary in any direction relative to the stack. For example, the permeability can be constant over the entire width of the stack, but can increase or decrease when moving from flow face to flow face of the stack. In alternative examples, the permeability can vary over the entire width of the stack alternatively. Other variations of the permeability area are also contemplated and designed to provide desired filter performance.

[0041] Many alternatives to the flow defining layer are envisioned and are considered to be within the scope of the present invention. In one exemplary embodiment of the flow defining layer, the layer is not provided with continuous strands, but rather comprises patterned structures, such as dots, dimples, pits and / or other raised or recessed structures arranged in a patterned grid. In another exemplary embodiment of the flow defining layer, the layer is provided with a completely random or partially random arrangement of dots, dimples, pits and / or other raised or recessed structures over the entire face of the flow defining layer.

[0042] Reference again Figure 1 , the contaminant retaining layer 14 is generally configured to capture contaminants or particles as material generally flows or passes over their first and second face surfaces 38, 40. However, because the material from which the contaminant retaining layer 14 is made may include a multi-fiber material formed into a sheet or layer, the face surfaces 38, 40 are textured in a manner such that contaminants will come into contact with the fibers as fluid flows over the surfaces. As with the flow limiting layer, the choice of filter material for the contaminant retaining layer may be selected to provide the filter with desired performance characteristics.

[0043] Figure 4 60-63 is a graph showing the initial (clean) particle removal efficiency of several exemplary filter materials for contaminant or particle retention according to the present invention. For this comparison, four flow-through filters having the same flow limiting layer but with different contaminant retention materials were constructed. The performance of these four filters relative to their respective efficiencies is represented by curves 60-63. The materials represented by curves 60-63 are arranged in a stack that is subjected to similar compression during its assembly, as will be discussed in further detail below. Figure 4 As shown, the ability of these flow-through filters to capture contaminants of different sizes with relatively equal efficiency can be controlled by utilizing a specific contaminant retention layer. For example, the samples represented by curves 61 and 63 produce relatively flat curves, indicating that the efficiency is relatively constant for all particle sizes. This consistent efficiency occurs through a filter media having a large number of pores within the size range of the particles to be captured as defined in the flow direction (i.e., relatively small pores are required to capture small particles). An exemplary material that can exhibit this quality is a filter having a β 1000 Synteq XP efficiency material for ≥ 4 μm (measured using ISO 16889) diesel flow-through filters, such as commercially available from Donaldson, Inc., Bloomington, Minn. This filter material is considered a high performance flow-through filter media that provides high filtration efficiency, provides relatively low differential pressure, has high dust holding capacity and is binder-free.

[0044] In order to increase the robustness of the filter material stack, it can be compressed or calendered in such a way that the fiber size of the material is maintained. Figure 4 The material represented by curve 63 provides such a compressed / calendered material, which shows slightly lower efficiency than those materials that have undergone less compression or calendering. Figure 4 Also shown in Figure 6 are curves 60 and 62 representing two additional materials, which are used as contaminant retention layers and do not exhibit a flat efficiency response curve. The filter of the present invention can be positioned in many different filter housings and configurations, wherein the amount of compression of the stack 10 can contribute to the specific performance results of the filter. That is, although the selection of the flow limiting layer 12 and the contaminant retention layer 14 is important for achieving the desired filtering performance, the compression of the stack of layers also contributes to the conditions required for achieving close inter-face contact between the flow limiting layer 12 and the adjacent contaminant retention layer 14. In an exemplary embodiment, a relatively low compression (e.g., undesirable low compression) allows a defect gap to be formed between the flow limiting layer 12 and the adjacent contaminant retention layer 14. When the contaminated fluid moves toward these gaps, the size of the gaps tends to expand, which provides a simple path for contaminants to flow more into and through the gaps. These defect areas therefore carry most of the fluid flow, as well as a correspondingly larger portion of the contaminants.

[0045] On the contrary, when there is too much compression in the stacked layer structure, it will be difficult to set up the initial flow path or channel of clear definition, and channel action may also occur, thereby causing fluid to be forced into the defective area, rather than along the expected flow path. Equally, the defective area gap will tend to expand in size, which forces even more streams and pollutants to pass through the gap. In this way, these defective areas will carry most of the fluid flow, and the corresponding larger part of the pollutant. In addition, these gaps produce the removal efficiency of reduction, thereby reducing the performance of the filter material. The expected compression amount is less than the amount that will force the pollutant retaining layer 14 to directly contact each other through the gap in the adjacent flow limiting layer 12, because this interface between the pollutant retaining layer will have the minimum or non-existent fluid flow along the flow-through type fluid flow path. In the case of not having fluid flow in these areas, the pollutant retaining layer 14 will not be able to capture the pollutant of the required amount according to the flow path defined by the layer of the present invention.

[0046] Reference now Figure 5Graphs showing the effect of compression on initial particle removal efficiency for layers arranged in a flow-through configuration, according to an embodiment of the present invention. For the purposes of the information obtained for this graph, fixed container geometries with varying numbers of stacked layers were provided in order to vary the compression of a stack of alternating layers such that compression was higher when more layers were included in the container. Specifically, line 70 represents a configuration with 50 layers in the stack (and therefore the lowest level of compression of the three samples), line 72 represents a configuration with 55 layers in the stack (and therefore the middle level of compression of the three samples), and line 74 represents a configuration with 60 layers in the stack (and therefore the highest level of compression of the three samples).

[0047] The pressure during the test was measured across (i.e., "flowing through") a layer of filters approximately 0.86 inches wide, 3 inches long, and 2 inches deep at a rate of 1 liter / minute in diesel fuel. The efficiency was measured using a particle counter and ISO12103-1 A2 (fine test dust). According to these configurations produced relative to the flow-through filter stack as described herein, the compression of the layers ranged from 1 psi to 3 psi, although higher or lower compression levels are considered to be within the scope of the present invention. The sample with the highest level of compression, represented by line 74, produced the greatest initial pressure drop and the greatest initial particle removal efficiency. The sample represented by line 70 produced the lowest initial pressure drop and had the lowest initial particle removal efficiency. The sample represented by line 72 had a moderate initial pressure drop and a moderate initial particle removal efficiency at almost all particle sizes except the smallest particles.

[0048] The compression on the stack of layers applied to a particular filter can be static, such as where the layers are positioned in a container or housing of fixed size. In this case, changing the compression on the stack will require adding or removing layers until the desired compression is achieved. However, it is also conceivable that the stack of alternating flow limiting layers and contaminant retaining layers can be subjected to variable compression, such as can be applied by a spring or other externally variable force. In this case, the compression on the stack can be changed to adapt to different fluids, operating conditions, etc.

[0049] The filtration performance indicators of both loading and contaminant capture efficiency contrast the differences between flow-through filters and flow-through filters. For flow-through filters, the removal efficiency of non-sticky contaminants is related to the pore size distribution of the media. This is because the probability that a contaminant will be captured and sieved is determined by how much of the fluid travels through pores that are smaller than the size of the contaminant. Figure 6As shown, this generally results in a greatly increased efficiency of the flow-through filter as the size of the contaminant increases. For this comparison, a relatively low contaminant concentration of 1 mg / 1 l was passed through both the flow-through filter system and the flow-through filter system for approximately 30 minutes, with the average initial beta removal values ​​recorded for a number of different contaminant sizes. Figure 6 A relatively flat curve is shown for the flow-through filter, which is an indication that the flow-through filter of the present invention can produce a relatively constant trend between removal efficiency and contaminant size.

[0050] However, if Figure 7 As shown in the graph of , the overall efficiency levels for flow-through filters are generally less than those typical for flow-through filters. The efficiency of the flow-through filter during loading is measured using a particle counter, and the upper line of the graph represents the efficiency for all particles equal to or larger than 4 μm. For the flow-through filter represented by the lower line of the graph, the efficiency increases during the loading process as the contaminants fill the media pore structure and increase the overall compactness of the media and dust cake. In this test, the efficiency was approximately 70% at the beginning of the test and increased to over 90% by the end of the test. In contrast, the efficiency of a flow-through filter is measured by a turbidometer, and Figure 7 The curve represents the collective measurement of all particles in a sample of 0 μm to 3 μm test dust. In this test, the efficiency was approximately 65% ​​at the beginning of the test and decreased to less than 40% at the end of the test. That is, the efficiency of the flow-through filter of the present invention is slightly reduced during loading, where the fluid passes only along the exposed face of the contaminant retaining layer, rather than flowing completely through the pore structure of the filter layer. Only after the surface pores of the contaminant retaining layer of the present invention are filled with contaminants is the efficiency observed to be greatly reduced.

[0051] Figure 8 A further comparison between a conventional flow-through filter and the flow-through filter of the present invention is shown in the graph of with respect to the change in the differential pressure measured across the filter as the filter is loaded with contaminants or particulates. Generally, the useful life of a flow-through filter is reached when the pressure rise associated with the captured contaminants reaches or exceeds a certain level. The threshold level or limit is generally determined by the acceptable pressure drop for the equipment in which the filter is installed. Such a limit may be referred to as "filter clogging" and requires either cleaning of the contaminants from the filter or removal and replacement of the filter for continued filter operation. Figure 8 For the purpose of the graph, the pressure differential change during loading was measured using a filter subjected to 40 mg / l fine test dust ISO12103-1 A2 in diesel at a flow rate of 1 liter / minute. The exposed media surface of the flow-through filter was approximately 620 cm 2In contrast, although the pressure differential of the flow-through filter of the present invention increased slightly during loading, the level of pressure increase was less than that found in the flow-through sample. Figure 8 For the purpose of the graph, the pressure differential change during loading was measured using a filter subjected to 40 mg / ml of fine test dust ISO12103-1 A2 in diesel fuel at a flow rate of 1 liter / minute. The exposed media surface of the flow-through filter was approximately 16.7 cm 2 , which differs from the size of the flow-through filters tested, where the size was chosen to simulate the flow rate relative to the filter size for a possible on-engine application. Figure 8 As shown, the flow-through filter has a relatively higher initial pressure difference and a lower pressure increase than the tested flow-through filter.

[0052] Fig. 9 Three exemplary configurations of the filtration system of the present invention having different depths are shown. The filter shown is made of 55 layers of both contaminant retaining media and flow limiting media, which are stacked into a housing occupying an area of ​​0.86" x 3". The edges of all layers are sealed by potting into epoxy resin (EPIC Resin S7292A&B) and mounted to a bottom steel plate. The first filter 80 is relatively short (e.g., 1 inch deep), the second filter 82 is taller than the first filter 80 (e.g., 2 inches deep), and the third filter 84 is taller than both filters 80, 82 (e.g., 4 inches deep). The three filters were tested by passing a contaminated fluid through the filters 80, 82, 84 in a flow direction 86 to determine the effect of depth on the performance of the flow-through filter of the present invention. According to this aspect of the filter of the present invention, "depth" refers to the length of the filter relative to the flow direction.

[0053] Figures 10 to 12 are graphs showing how varying the depth of a flow-through filter can increase its protection, efficiency, and pressure differential, respectively. For these graphs, the filter was constructed of a media comprising bicomponent binder fibers and microglass for the contaminant retaining layer and a flow limiting layer of polypropylene mesh R0412-10PR available from Delstar Technologies, Inc. of Middletown, Delaware. The filter assembly was subjected to a diesel flow at a rate of 1 liter / minute to remove fine test dust ISO12103-1 A2. The protection of the flow-through filter is shown in FIG. Fig.10, and refers to the pressure drop measured across a second filter placed downstream of the flow-through device. In both filter arrangements, the flow-through filter "protects" the second filter by capturing at least a portion of the contaminants. The time taken for the second filter to reach 10 kPa is measured, and this measurement is used to determine the relative amount of contaminants retained on the flow-through filter. In these tests, the control sample did not use a flow-through filter, and the downstream filter consisted of two layers of Synteq XP high efficiency material, such as commercially available from Donaldson, Inc. of Bloomington, Minnesota.

[0054] As discussed herein, the amount of filtration protection provided is related to the initial efficiency of the flow-through filter and how long that efficiency is maintained. The relationship between the initial efficiency of the flow-through filter and the depth of the exemplary filter is shown in Fig.11 The graph shows that the filter was subjected to a diesel flow at 1 liter / minute in order to remove fine test dust ISO12103-1 A2. When analyzed in terms of permeability, it is found that the amount of contaminants that pass through a flow-through filter generally has an exponential law dependence on depth. That is, for a flow-through filter of double the depth, the contaminant permeability is approximately the square root of the original permeability. Thus, if the depth of the filter is increased to three times its depth, it will deliver approximately the cube root of the original permeability. However, as Fig.12 As shown in the graph of , the increase in efficiency is consistent with the additional pressure difference across the filter, which illustrates the increase in pressure difference associated with a deeper filter. That is, a deeper flow-through filter is shown in this exemplary embodiment to remove more contaminants at the expense of a higher pressure difference.

[0055] The flow-through filters of the present invention may be provided in a variety of configurations, wherein each of these configurations involves a flow path in which fluid moves across the face of one or more contaminant retaining layers. Fig.13 A top view of an exemplary stack 90 of flow restricting layers and alternating contaminant retaining layers combined along one edge according to an embodiment of the present invention is shown. When used, this layer stack 90 can be positioned in a housing or other structure that compresses the layers by a desired amount and / or maintains the layer stack at a certain compression level once the layer stack is positioned in the housing. In an exemplary embodiment, the surface area of ​​the contaminant retaining material of the flow face of the compressed stack of materials of the present invention accounts for approximately 40%-80% of the total area of ​​the flow face.

[0056] use Fig.13In the embodiments of the present invention and other embodiments of the present invention, the number of layers in the stack can vary widely, but can be in the range of 40-100 layers per inch, or more specifically can be in the range of 55-75 layers per inch, or even more specifically 65 layers per inch. However, it should be understood that more or fewer layers can be used in a particular stack.

[0057] Fig.14 Another exemplary arrangement 120 of at least one flow defining layer 122 and at least one contaminant retaining layer 124 arranged in a coiled configuration about a central longitudinal axis 126 is shown. In this illustrated embodiment, the flow defining layer 122 is placed in contact with an adjacent contaminant retaining layer 124, and the pair of layers are coiled around themselves or around a core extending along the longitudinal axis 126 to form a cylindrical filter. In this configuration, the fluid will flow across the coiled surfaces of the flow defining layer 122 and the contaminant retaining layer 124 in a direction 128 from the top of the coiled layer (i.e., one end of the cylindrical filter) to the bottom of the coiled layer (i.e., the opposite end of the cylindrical filter). Alternatively, the fluid may flow in the opposite direction (i.e., from the bottom of the coil to the top of the coil).

[0058] Fig.15 Another exemplary configuration of a stack 100 of flow-defining disks 102 and alternating contaminant-retaining disks 104 arranged along a longitudinal axis 106 is shown. As shown, each of the disks 102, 104 has a central opening 108 such that each disk of the stack is concentrically positioned along the longitudinal axis 106. In this embodiment, the fluid will flow across the face of the contaminant-retaining disk 104 in a flow-through type flow path from the outer edge 110 of the disk toward the central opening 108 of the disk or from the central opening 108 of the disk toward the outer edge 110. That is, the fluid flow will be generally perpendicular to the longitudinal axis 106.

[0059] The present invention also contemplates other stack shapes besides cylindrical and rectangular, where the direction of fluid flow will cross the faces of the contaminant retaining layer and the flow limiting layer. For example, the stack can include layers having shapes that differ from one another along the height of the stack (such as hourglass, spherical, pear-shaped, irregular shapes, etc.) so as to be suitable for use in different filtration applications and devices. In addition, for example, in Figure 1 and Fig.13 As shown in , in any stack of layers, a particular retention layer and flow limiting layer may have similar or identical shapes and sizes. In other embodiments, the layers may be staggered along the height of the stack, such as if flow limiting layers or contaminant retaining layers are slightly different in size from other types of layers. For one example, a flow limiting layer may be slightly larger than a contaminant retaining layer, which may help establish a fluid flow path through the filter layer stack.

[0060] For any of the embodiments described herein, the filters of the present invention may include flow limiting layers and alternating contaminant retaining layers such that the ratio of different types of layers in the filter construction is approximately 1:1. In other embodiments of the present invention, the ratios may be different, such as providing a 2:1 ratio of flow limiting layers to contaminant retaining layers or a different ratio, or providing a 2:1 ratio of contaminant retaining layers to flow limiting layers or a different ratio. It is further contemplated that embodiments of the present invention do not include flow limiting layers, but the fluid flow is still directed along the faces of the contaminant retaining layers.

[0061] Fig.16 1 is a schematic diagram of another embodiment of a flow defining layer and a contaminant retaining layer arranged in a stack 150, which may be referred to as an asymmetric stack. As shown, the stack 150 includes a contaminant retaining layer 152 of varying thickness, such that a portion of the layer 152 at an edge 154 is thicker than a portion of the layer 152 at an opposite edge 156. As shown, the thickness may be tapered or may be provided as a more stepped configuration. Depending on the application, the difference between the thickness at the edges 154 and 156 may be small or large.

[0062] The stack 150 further includes a plurality of flow-restricting layers 158 of variable length positioned within the tapered region of each contaminant-retaining layer 152. In this embodiment, four such flow-restricting layers 158 are positioned within the tapered region, and one flow-restricting layer 158' is positioned between the flow-restricting layer 158 and the next adjacent contaminant-retaining layer 152; however, it should be understood that the ratio of flow-restricting layers 158 to contaminant-retaining layers 152 may be different than the 1:5 ratio shown in this figure. The number and ratio of layers 152 and 158 may also be selected based on the compression to be applied in the direction 159, which allows for specific fluid flows and filtering characteristics of the material to be filtered.

[0063] exist Fig.16 In the illustrated embodiment, the material flow moves relative to the layers 152, 158 in the direction 160 to provide the flow characteristics discussed herein (i.e., in a downward direction in this illustration). Thus, the flow face of this embodiment will be generally perpendicular to the flow direction 160. In an alternative use of the stack 150, the material flow moves in a direction opposite to the illustrated direction 160 (i.e., in an upward direction relative to this illustration). In other alternatives to this embodiment, the layer represented by reference numeral 152 may alternatively be a flow-restricting layer, and the layer represented by reference numeral 158 may be a contaminant retaining layer, wherein the contaminated material may flow in the direction 160 or the opposite direction.

[0064] Fig.171 is a schematic diagram of another embodiment of a flow limiting layer and a contaminant retaining layer arranged in a stack 170 that can be referred to as an asymmetric stack. As shown, the stack 170 includes a contaminant retaining layer 174 of varying thickness, which varies in thickness such that the portion of the layer 174 at the edge 176 is thicker than the portion of the layer 174 at the opposite edge 178. As shown, the thickness can be tapered, or can be provided as a more stepped configuration. Depending on the application, the difference between the thickness at the edges 176 and 178 can be small or large. The stack 170 further includes a plurality of flow limiting layers 172, which are tapered in a generally opposite manner to cooperate with the opposite contaminant retaining layer 174.

[0065] The tapering of the flow limiting layer 172 and the contaminant retaining layer 174 is intended to be exemplary in the illustrations and may alternatively include any number of different matching layers arranged to achieve a certain thickness and density for a particular filtration application. The number and ratio of layers 172 and 174 may be selected based on the compression to be applied to the stack that allows for specific fluid flows and filtration characteristics of the material to be filtered.

[0066] as Fig.16 An embodiment of Fig.17 The material flow of the embodiment of the present invention is in a direction relative to the layers 172, 174 to provide the flow characteristics discussed herein (e.g., in a downward direction in this illustration). Therefore, the flow face of this embodiment will be generally perpendicular to the flow direction. In this way, the contaminated material will first encounter more of the contaminant retaining layer as it enters the stack 170, wherein the proportion of the flow limiting layer encountered will increase as it moves through the stack. In an alternative use of this stack 170, the material flow moves in a direction in an upward direction relative to this illustration, so that the contaminated material will first encounter more of the flow limiting layer material as it enters the stack 170, wherein the proportion of the contaminant retaining layer encountered will increase as it moves through the stack.

[0067] The flow-through filter of the present invention described above can be used in a variety of filtering applications. For one example, the flow-through filter can be used alone in a system, wherein the predicted performance of the filter matches the filtering requirements of the system. For example, in other applications, the flow-through filter can be used in a multi-filter arrangement to provide the necessary protection for the fuel system of the engine. Possible other uses of the stacked / wound pre-filter include pre-filtration of bulk fuel, pre-filtration applied on the engine, replacement of the main filter applied on the engine, as a bypass filter for engine oil, as a kidney-shaped loop filter for engine oil, and / or as an engine oil filter.

[0068] The present invention has been described with reference to several embodiments of the present invention. The entire disclosure of any patent or patent application specified herein is hereby incorporated by reference. The above detailed description and examples are given only for the purpose of obtaining a clear understanding. No unnecessary limitations should be construed therefrom. It is clear to those skilled in the art that various modifications may be made to the described embodiments without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the structures described herein, but only to the structures described in the text of the claims and their equivalents.

Claims

1. A method for filtering a fluid, comprising the following steps: A filter is disposed in the fluid flow path, the filter comprising: a first flow face extending along a length and a width of the filter, wherein the first flow face includes at least one contaminant retaining layer first edge and at least one flow defining layer first edge; a second flow face spaced apart from the first flow face in an axial direction, wherein the second flow face extends along a length and a width of the filter and includes at least one contaminant retaining layer second edge and at least one flow defining layer second edge; at least one planar contaminant retaining layer, the at least one planar contaminant retaining layer extending from a first contaminant retaining layer edge to a second contaminant retaining layer edge; at least one planar flow defining layer adjacent to and in contact with at least one of the contaminant retaining layers, the at least one planar flow defining layer extending from a flow defining layer first edge to a flow defining layer second edge; a first filter region comprising a first portion of at least one contaminant retaining layer and a first portion of at least one flow defining layer, wherein the first filter region comprises a first permeability; and a second filter region adjacent to the first filter region, the second filter region comprising a second portion of the at least one contaminant retaining layer and a second portion of the at least one flow defining layer, wherein the second filter region comprises a second permeability different than the first permeability of the first filter region; wherein at least one of the flow defining layers causes material to flow in an axial direction as the fluid moves through the first filter region and the second filter region; and The fluid is moved along a fluid flow path, wherein the fluid flow path extends in an axial direction from the first flow face toward the second flow face such that the fluid travels through the first filter region and then through the second filter region. 2 . The method of claim 1 , wherein the first permeability and the second permeability vary from a first flow face to a second flow face of the filter.

3. The method of claim 1, wherein the first permeability and the second permeability vary across the width of the filter. The method of claim 1 , wherein the first permeability and the second permeability are measured between the first flow surface and the second flow surface. The method of claim 1 , wherein the at least one contaminant retaining layer comprises a plurality of contaminant retaining layers. The method of claim 1 , wherein the at least one flow defining layer comprises a plurality of flow defining layers.

7. The method of claim 1 further comprising alternating patterns of contaminant retaining layers and flow limiting layers across the width of the filter.

8. The method of claim 1, wherein at least one contaminant retention layer comprises a filter media extending from a first flow face to a second flow face.

9. The method of claim 1 in combination with a housing at least partially surrounding at least one contaminant retaining layer and at least one flow defining layer.

10. The method of claim 1, wherein the filter comprises a plurality of flow restricting layers and contaminant retaining layers arranged in a stack, and wherein the stack comprises a total of 40 to 100 flow restricting layers and contaminant retaining layers per inch.

11. A method for filtering a fluid, comprising the steps of: A filter device is disposed in a fluid flow path, the filter device comprising a plurality of layers arranged in a stack, wherein the stack comprises: at least one planar flow defining layer, the at least one planar flow defining layer comprising an upper edge, an opposing lower edge, a first flow face extending between the upper edge and the lower edge, and a second flow face extending between the upper edge and the lower edge; at least one planar contaminant retention layer, the at least one planar contaminant retention layer comprising an upper edge, an opposing lower edge, a first flow face extending between the upper edge and the lower edge, and a second flow face extending between the upper edge and the lower edge, wherein at least one of the first flow face and the second flow face of each flow defining layer is adjacent to at least one of the first flow face and the second flow face of one of the contaminant retention layers, and wherein each flow defining layer comprises a permeability different from a permeability of each contaminant retention layer; and a single fluid flow path in an axial direction from the first flow face to the second flow face, wherein each flow defining layer causes material to flow from an upper edge of the flow defining layer and the contaminant retaining layer toward a lower edge of the flow defining layer and the contaminant retaining layer; and Move the fluid along a single fluid flow path.

12. The method of claim 11 further comprising the step of compressing the stack prior to moving the fluid along the fluid flow path.

13. The method of claim 12, wherein the step of compressing the stack comprises placing the stack in an enclosure that provides a predetermined amount of compression of the stack.

14. The method of claim 12, wherein the step of compressing the stack comprises subjecting the stack to variable compression.

15. The method of claim 11, wherein the stack includes a total of 40 to 100 flow limiting layers and contaminant retaining layers per inch.

16. The method of claim 11, wherein the at least one contaminant retaining layer comprises a plurality of contaminant retaining layers.

17. The method of claim 11, wherein the at least one flow defining layer comprises a plurality of flow defining layers.

18. The method of claim 11, further comprising alternating patterns of contaminant retaining layers and flow limiting layers across the width of the filter.

19. The method of claim 11, wherein at least one contaminant retention layer comprises a filter media extending from a first flow face to a second flow face.

20. The method of claim 11 in combination with a housing at least partially surrounding at least one contaminant retaining layer and at least one flow defining layer.

21. The method of claim 11, wherein at least one flow defining layer comprises a patterned structure comprising at least one of dots, dimples, pits, raised structures, and recessed structures arranged in a patterned grid.

22. The method of claim 11, wherein at least one flow defining layer comprises an at least partially random arrangement of at least one of dots, dimples, pits, raised structures, and recessed structures.

Images