Filter with conductive wrap

Abstract

The invention relates to a filter for filtering particles from a fluid flow having an electrically conductive wrap comprising a filter element, a first end cap, a second end cap and a wrap. The end caps are fixed to the ends of the filter element, respectively, to form a fluid seal therebetween. At least one of the end caps defines an opening therethrough that is in fluid communication with an internal passage of the filter element. The wrap is in the form of a strip that is fixed to at least the filter element. The wrap comprises an electrically conductive layer comprising an electrically conductive material. The wrap is wrapped around the filter element such that at least forty percent of an outer surface area is covered by the electrically conductive layer.

Description

Technical Field

[0001] The present invention relates to filters having conductive wrapping. Background Technology

[0002] Filter cartridges have filter elements for filtering particles from a fluid flow. Filter elements subjected to radially inward (outside to inside) fluid flow typically have an inner core and an outer cage. Filter elements subjected to radially outward (inside to outside) fluid flow may not require an inner core. Some filter cartridges use a spiral wrapping instead of a cage to hold the filter element in the filter and reduce weight and cost.

[0003] Conventional porous media used in filter cartridges are typically non-conductive. It is known to process non-conductive fluids, such as non-polar hydrocarbons like gasoline, using porous media, such as filter media contained in filter cartridges. This fluid handling can become difficult or challenging due to the accumulation of triboelectric charge. Static charge tends to accumulate on the medium. If the accumulated charge is not properly released, it can form a spark, potentially igniting the fluid and creating a situation harmful to operators and property.

[0004] This problem has been recognized in many fields, such as the processing of food materials like flour, pumping pulverized coal or gasoline, coating textiles, and the filtration industry. See, for example, U.S. Patents 3,933,643, 5,527,569, and 5,229,200. Due to the need for high processing rates for economic reasons, the problem caused by electrostatic charge buildup can be significant at high flow rates and when small-pore porous media are used in performing this process.

[0005] Traditionally, triboelectric charging has been addressed through conductive filter media or complex grounding systems. Attempts have been made to reduce this risk, for example, by using porous media made of metal cloth, fibers, or powders. However, many of these media have limited filtration efficiency and pore size. Furthermore, their manufacture is expensive. There has been a persistent need in the art to provide alternative solutions to enhance fluid filtration while minimizing the accumulation of static or triboelectric charge.

[0006] It should be understood that the inventors of this invention have created this background description to assist the reader, and this background description should not be considered as an indication that any of the problems pointed out have themselves been recognized in the art. While the principles described may alleviate problems inherent in other systems in some aspects and embodiments, it will be understood that the scope of the protected innovation is defined by the appended claims, and not by the ability of any of the disclosed features to solve any specific problem pointed out herein. Summary of the Invention

[0007] In one aspect, the present invention relates to embodiments of filters. In embodiments, the filters can be used to filter particles from a fluid flow with a conductivity of less than 50 pS / m.

[0008] In one embodiment, a filter for filtering particles from a fluid flow includes a filter element, a first end cap, a second end cap, and a wrapping. The filter element extends along a longitudinal axis between the first and second ends. The filter element has an inner surface defining an internal passage and an outer surface defining an outer surface region. The filter element includes a filter medium.

[0009] A first end cap and a second end cap are respectively fixed to a first end and a second end of a filter element to form a fluid seal therebetween. At least one of the first end cap and the second end cap defines an opening therethrough, which is in fluid communication with an internal passage of the filter element.

[0010] The wrapping material is at least fixed to the filter element. The wrapping material includes a strip having a wrapping length and a wrapping width. The wrapping length is greater than the wrapping width. The wrapping material includes a conductive layer comprising a conductive material. The wrapping material wraps around the filter element such that at least 40% of the outer surface area is covered by the conductive layer.

[0011] In another aspect, the present invention relates to embodiments of fluid filter assemblies. In one embodiment, a fluid filter assembly for filtering particles from a fluid flow includes a housing and a filter.

[0012] The housing defines a first port, a second port, and a filter chamber. The first port and the second port communicate with the filter chamber, thereby defining a fluid flow path through the filter chamber between the first port and the second port.

[0013] The filter includes a filter element, a first end cap, a second end, and a wrapping. The filter element extends along a longitudinal axis between the first and second ends. The filter element has an inner surface defining an internal passage and an outer surface defining an outer surface region. The filter element includes a filter media.

[0014] A first end cap and a second end cap are respectively fixed to a first end and a second end of a filter element to form a fluid seal therebetween. At least one of the first end cap and the second end cap defines an opening therethrough, which is in fluid communication with an internal passage of the filter element.

[0015] The wrapping material is at least fixed to the filter element. The wrapping material includes a strip having a wrapping length and a wrapping width. The wrapping length is greater than the wrapping width. The wrapping material includes a conductive layer comprising a conductive material. The wrapping material wraps around the filter element such that at least 40% of the outer surface area is covered by the conductive layer.

[0016] The filter is positioned within the filter chamber of the housing such that it lies between the first and second ports along the fluid flow path, and the filter element is electrically connected to the housing.

[0017] In another aspect, this disclosure relates to embodiments of methods using filters. In one embodiment, a method of filtering particles from a fluid flow includes passing the fluid flow through a filter element, wherein the fluid flow has a conductivity of less than 50 pS / m.

[0018] The filter element extends along a longitudinal axis between a first end and a second end. The filter element has an inner surface defining an internal channel and an outer surface defining an outer surface region.

[0019] The wrapping material is electrically connected to ground. The wrapping material is at least fixed to the filter element. The wrapping material includes a strip having a length and a width. The length of the wrapping material is greater than the width. The wrapping material includes a conductive layer comprising a conductive material. The wrapping material wraps around the filter element such that at least 40% of the outer surface area is covered by the conductive layer.

[0020] Additional and alternative aspects and features of the disclosed principles will be understood from the following detailed description and accompanying drawings. It will be understood that the filter disclosed herein can be implemented and used in other and different embodiments, and can be modified in various aspects. Therefore, it should be understood that the foregoing general description and the following detailed description are merely exemplary and illustrative, and do not limit the scope of the appended claims. Attached Figure Description

[0021] Figure 1 This is a side view of an embodiment of a filter constructed according to the principles of this disclosure.

[0022] Figure 2 This is a perspective view of another embodiment of a filter constructed according to the principles of this disclosure, wherein one of the end caps is partially cut off to show the interior of the filter.

[0023] Figure 3 This is a plan view of an embodiment of a multilayer wrapping constructed according to the principles of the present disclosure, which is applicable to embodiments of filters constructed according to the principles of the present disclosure.

[0024] Figure 4 It is along Figure 3 The sectional view taken by line IV-IV in the diagram.

[0025] Figure 5 This is a plan view of two adjacent windings of a wrapper in an embodiment of a filter constructed according to the principles of this disclosure, illustrating a preferred exemplary embodiment of the wrapper layout.

[0026] Figure 6 This is a plan view of an embodiment of a single-layer wrapping constructed according to the principles of the present disclosure, which is applicable to embodiments of filters constructed according to the principles of the present disclosure.

[0027] Figure 7 It is along Figure 6 The sectional view taken from line VII-VII in the diagram.

[0028] Figure 8 This is a partial cross-sectional side view of an embodiment of a fluid filter assembly for filtering particles from a fluid flow, constructed in accordance with the principles of this disclosure.

[0029] It should be understood that the accompanying drawings are not necessarily drawn to scale, and the disclosed embodiments are schematic and shown in partial views. In some cases, details that are unnecessary for understanding the invention or that make other details difficult to understand may have been omitted. It should be understood that this disclosure is not limited to the specific embodiments shown herein. Detailed Implementation

[0030] Embodiments of filters constructed according to the principles of this disclosure are suitable for use with embodiments of filter assemblies constructed according to the principles of this disclosure for filtering particles from a fluid flow. Embodiments of filter assemblies constructed according to the principles of this disclosure can be used in embodiments of methods of using filters in accordance with the principles of this disclosure.

[0031] Embodiments of filters constructed according to the principles of this disclosure can be used in biopharmaceutical environments, but can also be used in other industrial applications using different fluids, solutions, reagents, and / or chemicals. Embodiments of filters constructed according to the principles of this disclosure can be used to filter particles from fluid flows having a conductivity of less than 50 pS / m. Embodiments of filters constructed according to the principles of this disclosure can be used to filter particles from fluid flows used in hydraulic or lubricant applications that are prone to generating triboelectric charging that leads to electrostatic discharge.

[0032] Embodiments of filters constructed according to the principles of this disclosure are configured to dissipate triboelectric charging to reduce the occurrence of electrostatic discharge. In embodiments of filters constructed according to the principles of this disclosure, the filter may include a filter element having an bonded conductive spiral wrap. The spiral wrap may include a single conductive layer or have a multi-layer construction, including at least one conductive layer and at least one carrier layer.

[0033] In embodiments of filters constructed according to the principles of this disclosure, the filter may include filter elements having a non-conductive filter medium. In embodiments, the filter medium may be substantially free of conductive filter media. In embodiments, the filter medium may have greater anti-gelling and / or dirt-holding capacity than known conductive filter media.

[0034] It should be understood that this detailed description provides exemplary embodiments of the invention. Since other embodiments of the invention may differ in detail from those described herein, the detailed description is intended to refer to the specific embodiments discussed at this point and is not intended to imply any limitation on the scope of the invention in a more general sense.

[0035] Now turn to the attached image. Figure 1 An embodiment of a filter 10 constructed according to the principles of this disclosure is shown. The filter 10 is configured to filter particles from a fluid flow and includes a filter element 20, a first end cap 21, a second end cap 22, and a wrapping 25.

[0036] The filter element 20 is cylindrical and adapted to filter material in response to fluid flow therethrough. First and second end caps 21, 22 (also referred to as “adapters”) are respectively secured to a first axial end 27 and a second axial end 28 of the filter element 20 to form a fluid seal therebetween. End caps 21, 22 seal the ends 27, 28 of the filter element 20, respectively. In an embodiment, at least one of the first end cap 21 and the second end cap 22 defines an opening 30 therethrough, which is in fluid communication with an internal passage 31 of the filter element 20 (see...). Figure 2 The wrapping material 25 is spirally wrapped around the outer surface 32 of the filter element 20. The wrapping material 25 includes a conductive layer 35 comprising a conductive material configured to help dissipate triboelectric charging and reduce the occurrence of electrostatic discharge. The filter 10 can be used to filter particles from a fluid flow with a conductivity of less than 50 pS / m, which is considered non-conductive.

[0037] Filter element 20 (also referred to as a “cylindrical package”) extends along the longitudinal axis LA between a first end 27 and a second end 28. Filter element 20 has an inner surface 37 defining an internal channel 31. The outer surface 32 of filter element 20 defines an outer cylindrical surface region 38. Those skilled in the art will understand that in other embodiments, filter element 20 may have different shapes, including non-cylindrical shapes, whose outer perimeter of cross-section is not circular, such as elliptical, square, triangular, or hexagonal.

[0038] In one embodiment, the filter element 20 includes a plurality of longitudinally curved pleats 41 or radial pleats (not shown). Those skilled in the art will understand that the wrapping 25 can be used in other embodiments of filters that include non-pleated filter elements, such as hollow cylindrical fiber blocks.

[0039] like Figure 2As shown, in one embodiment, the filter element 20 includes a cylindrical core 43 coaxially disposed within an internal channel 31. The core 43 defines a plurality of openings 45 spaced apart from each other in a regular pattern to allow fluid flow radially outward from an axial central aperture 47 of the core 43 or radially inward from the outside of the core 43 to the central aperture 47. In one embodiment, the core 43 may have any suitable structure, including conventional designs, and may be made of any material having sufficient strength for the intended application and being compatible with the fluid to be filtered, as understood by those skilled in the art.

[0040] When the filter element 20 is subjected to radially inward fluid flow, the core 43 is generally desirable because it supports the inner periphery of the filter element 20 against radial forces, thus maintaining the construction of the filter element 20 and also helping to give the filter 10 strength and stiffness against bending. Alternatively, when the filter element 20 is subjected to radially outward (from inside to outside) fluid flow, the core 43 can be omitted, thereby reducing the weight and cost of the filter.

[0041] Reference Figure 1 In embodiments of filters constructed according to the principles of this disclosure, the filter 10 is equipped with end caps 21, 22 at one or both of the axial ends 27, 28 of the filter element 20. The end caps 21, 22 can be closed or open and can be made of materials suitable for the filter conditions and other materials of the filter components to which the end caps 21, 22 are to be joined. In embodiments, the end caps 21, 22 are attached to the filter element 20. Conventional techniques can be used to attach the end caps 21, 22 to the filter element 20, such as by polycapping or rotational welding, or by using epoxy resin.

[0042] Reference Figure 2 The filter element 20 includes multiple pleats 41. Figure 2 (Only a few are shown in the image). These pleats are arranged in close contact with each other to define the cylindrical shape of the filter element 20. Each pleat 41 of the filter element 20 has a pair of legs 41a connected to each other: (1) at the crown or top 41b of the outer periphery of the filter element 20, and (2) at the root 41c of the inner periphery of the filter element 20, connecting to the leg 41a of the adjacent pleat 41. Each leg 41a has an inner surface 41d opposite to the inner surface 41d of another leg 41a in the same pleat 41. Each leg 41a also has an outer surface 41e opposite to the outer surface 41e of the leg 41a of the adjacent pleat 41.

[0043] The opposing inner surfaces 41d of the legs 41a of each pleat 41 contact each other over a continuous region covering at least a major portion of the height of the legs 41a and pleats 41 and the axial length of the filter element 20 extending along the longitudinal axis LA. Additionally, the opposing outer surfaces 41e of the legs 41a of adjacent pleats 41 contact each other over a continuous region covering at least a major portion of the height of adjacent pleats 41 and legs 41a and the axial length of the filter element 20 extending along the longitudinal axis LA. The height of the pleats 41 and legs 41a is measured in a direction along the surface of the legs 41a and extends from the inner periphery to the outer periphery of the filter element 20.

[0044] When filter element 20 is used to allow fluid to flow radially inward through element 10, outer surface 41e forms the upstream surface of filter element 20, while inner surface 41d of leg 41a forms the downstream surface of filter element 20. When filter element 20 is subjected to radially outward fluid flow, inner surface 41d of leg 41a forms the upstream surface of filter element 20, while outer surface 41e forms the downstream surface of filter element 20.

[0045] Figure 1-2 The illustrated curved pleat construction allows for uniform pleat support and serves to evenly distribute concentrated loads across filter element 20, thereby reducing pleat movement and increasing the pleats' ability to retain particles in a pulsating flow system. Those skilled in the art will understand that, in embodiments, filter element 20 may include curved or stacked pleats (such as... Figure 2 (as shown) or conventional radial pleats (not shown). In an embodiment, the pleated legs 41a have legs of equal length. In other embodiments, especially when the filter element 20 is formed of a multilayer composite material, the pleated legs 41a may have slightly different or unequal lengths.

[0046] Reference Figure 2In an embodiment, the filter element 20 includes a filter medium 50 and discharge devices disposed on at least one side, preferably a predetermined upstream side, more preferably an upstream side and a downstream side, of the filter medium 50, as those skilled in the art will understand. In an embodiment, the opposing surfaces of the curved pleats 41 are compressed into contact with each other. Thus, the strands of the discharge mesh of each leg 41a of the pleats 41 are pressed against the strands of the discharge mesh of the adjacent leg 41a of the pleats 41. When the curved pleats 41 are used in the filter element, the discharge devices prevent the opposing surfaces of the filter medium 50 from contacting each other and allow fluid to flow uniformly to or from substantially all portions of the surface of the filter medium 50. Thus, almost the entire surface area of ​​the filter medium 50 can be effectively used for filtration. When radial pleats are used in the filter element 20, there is generally sufficient space between the upstream and downstream sides of the pleat legs to allow fluid to flow uniformly to or from substantially all portions of the surface of the filter medium 50.

[0047] exist Figure 2 In one embodiment, the filter element 20 comprises a three-layer composite material consisting of a filter medium 50, a discharge device in the form of a first discharge layer 51 disposed outside the filter medium 50, and a discharge device in the form of a second discharge layer 52 disposed inside the filter medium 50. Here, when the filter 10 is subjected to a radially inward fluid flow, the outer and inner surfaces of the filter medium refer to the upstream and downstream surfaces, respectively. When the filter 10 is subjected to a radially outward fluid flow, the upstream and downstream surfaces are reversed. The layers forming the filter element 20 can be formed as a composite material using conventional filter manufacturing techniques before or during wrinkling.

[0048] The emission layers 51 and 52 may comprise any suitable material known to those skilled in the art. In an embodiment, at least one of the first emission layer 51 and the second emission layer 52 may comprise a polymer web or an extruded or woven polymer web.

[0049] In embodiments, any suitable filter media can be used in a filter constructed according to the principles of this disclosure, and it can be selected based on the fluid intended to be filtered and the desired filtration characteristics. Filter media 50 can be used to filter various fluid flows, such as liquids, gases, or mixtures thereof.

[0050] In embodiments, filter media 50 may include a membrane, a porous membrane, or a sheet or block of fibers; it may have a uniform or hierarchical pore structure and any suitable effective pore size. Filter media 50 may be formed from any suitable material, such as natural or synthetic polymers, glass, or metal. Filter media 50 may include a single layer, or filter media 50 may include multiple layers of the same media stacked on top of each other at a desired thickness. Furthermore, filter media 50 may include two or more layers with different filtration properties; for example, one layer may serve as a pre-filter for a second layer. In another embodiment, filter element 20 may include several integral regions, including a single integral porous sheet with a fine pore central region serving as the filter media, and upstream and / or downstream regions with coarse pores serving as the discharge layer.

[0051] In this embodiment, the first and second discharge layers 51, 52 are separate layers from the filter medium 50. The first and second discharge layers 51, 52 may have the same or different structures. The first and second discharge layers 51, 52 may be made of any material with suitable edgewize flow characteristics, i.e., suitable resistance to fluid flowing through the layer in a direction parallel to its surface. The edgewize flow resistance of each discharge layer 51, 52 is preferably low enough that the pressure drop in the discharge layers 51, 52 is less than the pressure drop across the filter medium 50, thereby providing a uniform distribution of fluid along the surface of the filter medium 50. In this embodiment, the discharge layers 51, 52 may be in the form of a mesh or sieve or a porous woven or nonwoven sheet.

[0052] When the filter medium 50 is a fiber-laid medium, a mesh is particularly suitable as an outlet layer. On the other hand, when the filter medium 50 is a membrane, woven or nonwoven fabrics may be more suitable as outlet layers 51, 52, because fabrics are generally smoother than meshes and produce less wear between adjacent layers of the filter composite.

[0053] In embodiments, the filter composite material forming the filter element 20 may include layers other than the filter media 50 and the discharge layers 51, 52. For example, to prevent wear of the filter media 50 due to frictional contact with the discharge layers 51, 52 during pressure fluctuations in the fluid system in which the filter 10 is installed, a buffer layer may be provided between one or both of the filter media 50 and the discharge layers 51, 52. This buffer layer is preferably made of a material that is smoother than the discharge layers 51, 52 and has higher abrasion resistance than the filter media 50. For example, when the discharge layers 51, 52 are made of extruded nylon mesh, a suitable example of a suitable buffer layer is a polyester nonwoven fabric.

[0054] Advantageously, the filter medium 50 can be configured to be non-conductive and for filtering particles from a non-conductive fluid flow. The wrapping 25 can be used to reduce the accumulation of triboelectric charge. In embodiments, the filter medium 50 is made of any suitable non-conductive material. In embodiments, the filter medium 50 may include a hydrophilic material. In embodiments, the filter medium 50 may include non-conductive fibers made of suitable materials, such as glass, ceramic polyester, cellulose, rayon, and polypropylene. For example, in embodiments, the filter medium 50 contains at least 99% glass fiber by weight, and in other embodiments it is substantially composed of glass fiber.

[0055] In this embodiment, the filter medium 50 is configured to have a relatively high basis weight compared to conventional conductive media. High basis weight media have a high specific surface area (square meters of surface area per square foot of media), which contributes to a high dirt-holding capacity per square foot of media. For example, in this embodiment, the filter medium 50 has a basis weight of at least 3 grams per square foot (gpsf). In other embodiments, the basis weight of the filter medium 50 is at least 3.5 gpsf, and in other embodiments at least 4 gpsf.

[0056] In this embodiment, the filter medium 50 has a density of at least 4m. 2 / ft 2 The specific surface area. In this embodiment, the filter medium 50 has a specific surface area of ​​at least 5 m². 2 / ft 2 The specific surface area is at least 6 m² in other embodiments. 2 / ft 2 Specific surface area.

[0057] Reference Figure 1 The wrapping 25 includes a conductive layer 35 comprising a conductive material. In embodiments, the conductive layer 35 of the wrapping 25 may be made of any suitable conductive material. For example, in embodiments, the conductive material of the conductive layer 35 comprises a permeable nonwoven nylon impregnated with at least one of carbon and a conductive polymer. In other embodiments, the conductive material of the conductive layer 35 comprises a conductive metal.

[0058] The wrapping material 25 comprises a strip having parallel sides 71, 72, a wrapping length L (measured along an axis parallel to sides 71, 72), and a wrapping width W (measured laterally along an axis transverse to sides 71, 72), wherein the wrapping length L is greater than the wrapping width W. The wrapping material 25 shown comprises a strip of flexible material with parallel sides, spirally wrapped around the filter element 20 in multiple windings. In embodiments where the wrapping material 25 completely encloses the outer periphery of the filter element 20, the wrapping material 25 is preferably permeable. Although the filter element 20 preferably includes pleats, in other embodiments, the wrapping material 25 may be used with a pleated filter bag, such as a hollow cylindrical fiber block.

[0059] In one embodiment, the wrapping material 25 is made of a porous material. In another embodiment, the wrapping material 25 may be made of a suitable material compatible with the fluid being filtered. In yet another embodiment, the wrapping material 25 is made of a sufficiently strong material to provide adequate support against radially outward forces and against stresses generated by inward-to-outward flow. The tension of the wrapping material 25 can be selected according to the desired filtration conditions.

[0060] In an embodiment, the wrapping material 25 is at least secured to the filter element 20. In an embodiment, the wrapping material 25 can be secured to the filter element 20 via any suitable technique, as those skilled in the art will understand. In an embodiment, the wrapping material 25 is bonded to the filter element 20 by adhesive or mechanical bonding, such that the wrapping material 25 is arranged in contact with and secured in place therewith. The wrapping material 25 is preferably secured in a manner that prevents it from loosening from the filter element 20. In an embodiment, the wrapping material may be configured to attach to at least one of the end caps 21, 22 and resist radially outward forces generated by pressure drops across the filter element.

[0061] In one embodiment, the wrapping 25 can be attached to the outer surface 32 of the filter element 20 by applying beads of hot melt adhesive to the two longitudinally extending sides 71, 72 of the wrapping 25. Hot melt adhesive can flow into the porous sides 71, 72 on each side.

[0062] In one embodiment, the wrapping material 25 is attached at its end to a corresponding one of the end caps 21, 22. In embodiments where the wrapping material 25 is attached to at least one of the end caps 21, 22, the wrapping material 25 is preferably inserted into the respective end cap 21, 22 at least 50 / 100 inches, and more preferably into at least 100 / 100 inches. In another embodiment, before the wrapping material 25 is attached to the end caps 21, 22, the axial end of the wrapping material 25 is cut at an angle such that substantially the entire cut end can be inserted into and attached to the end caps 21, 22.

[0063] In one embodiment, the wrapping material 25 is wrapped around the filter element 20 in such a way that it provides a sufficient conductive surface area provided by the conductive layer 35 to effectively interact with the filtered fluid flow, thereby dissipating triboelectric charge. In another embodiment, the wrapping material 25 wraps around the filter element 20 such that at least forty percent of the outer cylindrical surface area 38 is covered by the conductive layer 35. In other embodiments, the wrapping material 25 wraps around the filter element 20 such that at least fifty percent of the outer cylindrical surface area 38 is covered by the conductive layer 35.

[0064] In the illustrated embodiment, the wrapping material 25 is helically wrapped around the filter element 20 to form a plurality of helical windings along the longitudinal axis LA. The helical windings are spaced apart from each other to define a gap G between adjacent helical windings. The wrapping material 25 is helically wrapped around the filter element 20 at a helix angle γ. In this embodiment, the helix angle γ is not parallel to a transverse plane T perpendicular to the longitudinal axis LA. In this embodiment, the wrapping material 25 is helically wrapped around the filter element 20 to form a plurality of adjacent windings under tension to help hold the filter element 20 in a cylindrical configuration.

[0065] In embodiments, the wrapping material 25 may wrap around the filter element 20 with or without overlap between adjacent windings of the wrapping material 25. For example, adjacent windings of the permeable wrapping material 25 may be adjacent to each other substantially without overlap, or multiple layers of the permeable wrapping material 25 may be wrapped around the filter element 20 by employing overlap. In embodiments, the wrapping material 25 may define openings therethrough to increase permeability.

[0066] refer to Figure 2 In this embodiment, the conductive layer 35 is configured to provide a current path for efficiently dissipating triboelectric charge. The provision of the conductive layer 35 allows the filter 10 to filter fluid flows with a conductivity of less than 50 pS / m through the filter element 20 of the non-conductive filter medium 50, which has a relatively high specific surface area. A high specific surface area is generally undesirable in triboelectric applications, as it is expected to lead to more charge accumulation and eventual electrostatic discharge. In this embodiment, the conductive layer 35 has a sheet resistance (ohms per square ohm) of less than 50 kΩ / sq. In other embodiments, the conductive layer 35 has a sheet resistance of less than 45 kΩ / sq, and in other embodiments, less than 40 kΩ / sq.

[0067] In an embodiment, the wrapping 25 may include, be substantially composed of, or be composed of a conductive layer 35. In an embodiment, the wrapping 25 may have a multilayer structure.

[0068] For example, in Figure 1 and 2In the illustrated embodiment, the wrapping material 25 includes a conductive layer 35 and a carrier layer 75. The wrapping material 25 can be fixed to the filter element 2 such that the conductive layer 35 is disposed facing the outer surface 32 of the filter element 20, and the carrier layer is disposed outward relative to the conductive layer 35.

[0069] In one embodiment, the carrier layer 75 is attached to the filter element 20 to resist radial outward expansion of the filter element 20. In another embodiment, the carrier layer 75 has a grip tensile strength of at least 90 N along the wrapping length L.

[0070] Reference Figure 3 and 4 , showing the use of Figure 1 and 2 The wrapping material 25 in the filter 10. The wrapping material 25 includes embodiments of wrapping materials constructed according to the principles of the present disclosure. The wrapping material 25 is suitable for embodiments of the filter 10 constructed according to the principles of the present disclosure.

[0071] In an embodiment, the conductive layer 35 is fixed to the carrier layer 75. In an embodiment, any suitable technique can be used to fix the conductive layer 35 to the carrier layer 75. For example, in an embodiment, the conductive layer 35 is fixed to the carrier layer 75 by ultrasonic, thermal, or adhesive bonding. In an embodiment, the conductive layer 35 is fixed to the carrier layer 75 by: applying double-sided adhesive tape between the conductive layer 35 and the carrier layer 75; applying a hot melt adhesive, such as polyamide hot melt adhesive or EVA hot melt adhesive, between the conductive layer 35 and the carrier layer 75; or by ultrasonic spot welding the conductive layer 35 and the carrier layer 75.

[0072] In the illustrated embodiment, the conductive layer 35 has a conductive layer width COW, and the carrier layer 75 has a carrier layer width CAW that is greater than the conductive layer width COW. In this embodiment, the conductive layer width COW is equal to or less than the carrier layer width CAW.

[0073] In an embodiment, the conductive layer 35 is fixed to the carrier layer 75 such that the conductive layer 35 is laterally disposed within or aligned with the carrier layer. In an embodiment, the conductive layer width COW is within the range of (1) half the carrier layer width CAW and (2) the carrier layer width CAW. In the illustrated embodiment, the conductive layer 35 is narrower than the carrier layer 75 and is laterally disposed within the carrier layer 75.

[0074] In embodiments, the carrier layer 75 can be made of any suitable material. For example, in embodiments, the carrier layer 75 can be formed of a suitable spunbond thermoplastic material that is compatible with the filtered fluid and will readily bond to an adhesive such as a hot melt adhesive. The carrier layer 75 is preferably porous to allow the hot melt adhesive to penetrate into the carrier layer 75 to form a stronger bond. In embodiments, the carrier layer 75 is perforated to enhance its permeability.

[0075] In embodiments, the carrier layer 75 may include a non-conductive material, be substantially composed of a non-conductive material, or be composed of a non-conductive material. For example, in embodiments, the material of the carrier layer 75 includes, is substantially composed of, or is composed of, permeable nonwoven polyester or nylon.

[0076] In an embodiment, the carrier layer 75 comprises a material different from the conductive material of the conductive layer 35. For example, in an embodiment, the conductive layer 35 comprises a commercially available conductive material, such as Nystat, that is available from Cerex Advanced Fabrics, Inc. of Cantoment, Florida. TM 50 conductive nylon material, and the carrier layer 75 comprises various commercially available materials, such as at least one of the following: available by trademark from Fiberweb Corporation of Old Hickory, Tennessee. Commercially available polyester materials, such as grades 2016, 2024, or 2033, and commercially available nylons, such as grades 70, 85, 100, or 150, are available from Cerex Advanced Fabrics, Inc., Cantoment, Florida.

[0077] The multilayer wrap 25 can be manufactured using any suitable technique that will be understood by those skilled in the art. For example, in one embodiment, the multilayer wrap 25 is manufactured by bonding a conductive layer 35 to a suitable carrier layer 75 via ultrasonic spot bonding. The conductive layer 35 is in the form of a conductive gauze made of impregnated nylon with a sheet resistance of less than 50 kΩ / sq, and the carrier layer 75 is made of a polyester spunbond material having a tensile strength of at least 90 N in the machine direction.

[0078] In embodiments, the conductive layer 35 may have other strip-like configurations. For example, in other embodiments, the double-layer wrapping 25 may be formed by wet-laying metal fibers, such as stainless steel or copper, and an adhesive to form the conductive layer 35 on the carrier layer 75. In other embodiments, the double-layer wrapping 25 may be formed by bonding the conductive layer 35 in the form of metal wires or metal mesh to the carrier layer 75 with an adhesive. In yet another embodiment, the double-layer wrapping 25 may be formed by stamping the conductive layer 35 in the form of a conductive fiber pad together with the carrier layer 75.

[0079] See Figure 5 In one embodiment, the wrapping material 25 is helically wrapped around the filter element 20 to form a plurality of helical windings 81, 82 along the longitudinal axis LA. The helical windings 81, 82 are spaced apart from each other to define a gap G between adjacent helical windings 81, 82. The wrapping material 25 is helically wrapped around the filter element 20 at a helix angle γ that is not parallel to a transverse plane T perpendicular to the longitudinal axis LA. Adjacent windings 81, 82 of the wrapping material 25 have a gap width G measured along an axis perpendicular to the helix angle γ. In one embodiment, the conductive layer width COW is greater than forty percent of the sum of the carrier layer width CAW and the gap width G. In one embodiment, the pitch between adjacent windings 81, 82 of the wrapping material 25 is configured such that the conductive layer width COW of the conductive layer 35 is at least forty percent of the carrier layer width CAW of the carrier layer 75 plus the gap G between adjacent windings 81, 82 (COW ≥ 0.4 × (CAW + G)).

[0080] In one embodiment, the multilayer wrapping 25 includes a conductive layer 35 and a carrier layer 755, the conductive layer 35 including Nystat TM The carrier layer 75 comprises 50 conductive nylon with a one-inch conductive layer width COW, and includes non-conductive components. The filter element 20 is made of 2033 polyester and has a carrier layer width (CAW) of 1.35 inches. A conductive layer 35 can be mounted onto the carrier layer 75, such that the conductive layer 35 is laterally centered within the carrier layer 75. The two layers 35 and 75 can be welded together with a 0.125-inch long hot weld seam across their widths, wherein the weld seam repeats along length L at intervals between six and twelve inches. The wrapping 25 can be spirally wrapped around the filter element 20 such that the gap G between adjacent windings is 0.75 inches, resulting in a coverage of 47.6% of the conductive layer 35 on the outer cylindrical surface region 38 (COW / (CAW+G)=1 / (1.35+0.75)=0.476).

[0081] Reference Figure 6 and Figure 7An embodiment of a wrap 125 constructed according to the principles of this disclosure is shown. The wrap 125 is suitable for embodiments of filters constructed according to the principles of this disclosure. The wrap 125 is composed of a conductive layer 135. In an embodiment, the conductive layer 135 has a tensile strength of at least 90 N along the wrap length L'. In an embodiment, the wrap 125 composed of the conductive layer 135 can be made of any suitable material. For example, in an embodiment, the conductive layer 135 can be made of carbon-impregnated nylon spunbond having a basis weight of about 55 g / m².

[0082] In one embodiment, the wrapping 125, consisting of the conductive layer 135, may be helically wrapped around the filter element. In another embodiment, the pitch between the windings of the wrapping 125 is such that the width W' of the wrapping is greater than forty percent of the sum of the width W' of the wrapping and the gap G between the windings.

[0083] The filter element 20 in embodiments applicable to filters constructed according to the principles of this disclosure can be manufactured using a variety of techniques. In one technique, a filter composite material comprising a suitable filter medium, a support, and a discharge element is first pleated to form a pleated sheet, cut to a suitable length or a suitable number of pleats, and then formed into a cylindrical shape. The longitudinal edges of the pleated sheet are then sealed together to form a filter bag using conventional methods. For example, the ends of the pleated filter bag can be sealed using an ultrasonic sealing welding system.

[0084] The wrapping material 25 can be helically wrapped around the length of the filter bag. The tension applied to the wrapping material 25 is sufficient to prevent movement of the pleats 41 or corrugations in the wrapping material 25 between the pleats 41, without crushing or sealing the pleats 41 of the filter bag. In an embodiment, gaps are formed between adjacent windings of the helical wrapping material 25 such that at least forty percent of the outer surface area of ​​the filter element is covered by the conductive layer 35. The filter bag can be manufactured to the desired length (e.g., 42-44 inches), and the wrapping material 25 can be applied over the entire length. In an embodiment, the wrapping material can be applied circumferentially in the form of strips (parallel to a plane transverse to the longitudinal axis of the filter bag), the strips being regularly spaced apart from each other.

[0085] The wrapping material 25 can be directly attached to the filter element 20. In one embodiment, the wrapping material 25 is attached to the filter element 20 by an adhesive, such as a hot melt adhesive, applied to the wrapping material as it is wrapped around the filter element 20. The adhesive can be applied to the wrapping material 25 in the form of continuous or intermittent beads, the beads spirally wrapped around the filter element 20 parallel to the edge of the wrapping material 25. In other embodiments, the wrapping material 25 is fused to the filter element 20 by a heat wheel that travels along the length of the filter element 20 as the filter element 20 rotates.

[0086] In this embodiment, two layers of wrapping material 25 are used to wrap the filter element 20. The layers of wrapping material 25 are bonded together, and each layer is 1.35 inches wide. The wrapping material 25 is spirally wrapped around the filter element, with a gap of 0.75″ between adjacent windings. The wrapping material 25 is bonded to the filter element 20 via a hot melt adhesive.

[0087] In this embodiment, it should be understood that the carrier layer 75 is wider than the conductive layer 35. Therefore, when the wrap 25 is bonded to the end caps 21, 22, the carrier layer 75 helps prevent the conductive layer 35 from separating from the end caps 21, 22 and the filter bag. The carrier layer 75 may be made of a material capable of enhancing bonding with adhesives and potting materials used in the manufacture of the filter element. The wider carrier layer 75 can be configured to provide better handling and performance during manufacturing and reduce the occurrence of separation between the conductive layer 35 and the end caps 21, 22 and the filter bag, while maintaining the conductive properties of the conductive layer 56. The wider carrier layer 75 also helps to maintain the diffusion of the adhesive within the periphery of the wrap 25 and reduces undesirable soiling that could occur if the adhesive diffused outside the periphery of the wrap.

[0088] Subsequently, the combined wrapper and filter bag can be cut to the desired length. In embodiments, the combined wrapper and filter bag can be cut to lengths such as 40 inches, 20 inches, 13 inches, 8 inches, or 4 inches.

[0089] After the combined filter bag and wrapping are cut to the desired length, it can be sealed to form filter element 20. In an embodiment, the combined filter bag and wrapping are sealed at one end of the filter bag with an open adapter and at the other end with a closed adapter.

[0090] End caps 21 and 22 can be applied using suitable encapsulating compounds, including, for example, epoxy, polyurethane, or hot melt adhesives. End caps 21 and 22 can be made of metal or polymer. In embodiments, polymer end caps can be applied to the ends of filter element 20 by melting a portion of the polymer end cap and inserting the end of filter element 20 into the molten portion of end caps 21 and 22. In either case, the end of filter element 20 should preferably be inserted into the encapsulating compound or molten plastic at least 50 per thousand inches, and more preferably about 100 per thousand inches, to ensure that the wrapping 25 is properly bonded to the filter element at end caps 21 and 22.

[0091] Reference Figure 8This illustration shows an embodiment of a fluid filter assembly 80 constructed according to the principles of the present disclosure for filtering particles from a fluid flow. The fluid filter assembly 80 includes an embodiment of a housing 82 and a filter 85 constructed according to the principles of the present disclosure. In embodiments, the fluid filter assembly 80 for filtering particles from a fluid flow, constructed according to the principles of the present disclosure, may include any embodiment of a filter constructed according to the principles of the present disclosure.

[0092] In one embodiment, housing 82 defines a first port 87, a second port 88, and a filter chamber 89. The first port 87 and the second port 88 communicate with the filter chamber 89, such that a fluid flow path 90 is defined by the filter chamber 89 between the first port 87 and the second port 88. In the illustrated embodiment, filter 85 is constructed similarly to... Figure 1 and Figure 2 The illustrated embodiment. In other embodiments, another embodiment of the filter constructed according to the principles of this disclosure may be used.

[0093] The filter 85 includes a filter element 220, a first end cap 221, a second end 222, and a wrapping 225. In an embodiment, the filter element 220 includes a filter medium made of a non-conductive material.

[0094] The first end cap 221 and the second end cap 222 are respectively fixed to the first end and the second end of the filter element 220 to form a fluid seal therebetween. In an embodiment, at least one of the first end cap 221 and the second end cap 222 defines an opening 230 therethrough, which is in fluid communication with the internal channels of the filter element.

[0095] The wrapping material 225 is at least fixed to the filter element 220. The wrapping material 225 includes a conductive layer comprising a conductive material. The wrapping material 225 wraps around the filter element 220 such that at least forty percent of the outer surface area of ​​the filter element 220 is covered by the conductive layer. In embodiments, the wrapping material 225 may otherwise be similar to other embodiments of wrapping materials including the conductive layer described above.

[0096] Filter 85 is located within filter chamber 89 of housing 82, such that filter 85 lies between first port 87 and second port 88 along a fluid flow path, and such that filter element 220 is electrically connected to housing 82. Filter 85 can be electrically connected to ground via connection to housing 82 and conduit thereto. In embodiments, electrical ground includes earth ground, but in other embodiments, it may include floating or chassis ground, as those skilled in the art will understand. In embodiments, first end cap 221 and core 243 may be made of conductive material. In the illustrated embodiment, the core 243 of filter element 220 (for simplicity, in...) Figure 8(The opening is not shown in the image) and the enclosure 229 are in electrical contact with the base 92 in the housing 82 via the first end cap 221.

[0097] In embodiments where filter 85 does not include a core, housing 82 may include a fixed core. The wrapping of the filter element of the coreless filter may be positioned to make electrical contact with the core of housing 82 to ground filter 85 via any suitable technique, such as by means of at least one end cap made of conductive material.

[0098] Embodiments of filters constructed according to the principles of this disclosure can be used to perform methods for filtering particles from a fluid flow following the principles of this disclosure as described above. In embodiments, the method of using a filter following the principles of this disclosure can be used in conjunction with any embodiment of a filter constructed according to the principles discussed herein.

[0099] In one embodiment, a method of filtering particles from a fluid flow includes passing the fluid flow through a filter element, wherein the fluid flow has a conductivity of less than 50 pS / m. The filter element is cylindrical and extends along a longitudinal axis between a first end and a second end. The filter element has an inner surface defining an internal channel and an outer surface defining an outer cylindrical surface region.

[0100] The wrapping material is electrically connected to ground. The wrapping material is at least fixed to the filter element. The wrapping material includes a strip having a length and a width. The length of the wrapping material is greater than the width. The wrapping material includes a conductive layer comprising a conductive material. The wrapping material is wrapped around the filter element such that at least forty percent of the outer cylindrical surface area is covered by the conductive layer.

[0101] All references cited in this article, including publications, patent applications and patents, are incorporated herein by reference to the extent that each reference is individually and specifically indicated to be incorporated herein by reference and discussed in its entirety.

[0102] The terms “a,” “an,” and “the,” and similar indicators used in the context of describing the invention (particularly in the context of the following claims) should be interpreted to cover both singular and plural forms unless otherwise stated herein or obviously contradicted by the context. The terms “comprising,” “having,” “including,” and “containing” should be interpreted as open-ended terms (i.e., meaning “including but not limited to”) unless otherwise stated. Unless otherwise stated herein, descriptions of numerical ranges are intended only as a shorthand method for individually referring to each individual value falling within that range, and each individual value is incorporated into the specification as if it were individually described herein. Unless otherwise stated herein or obviously contradicted by the context, all methods described herein may be performed in any suitable order. Unless otherwise required, the use of any and all instances or exemplary language (e.g., “such as”) provided herein is intended only to better illustrate the invention and not to limit the scope of the invention. The language in the specification should not be construed as indicating that any unclaimed element is necessary for the practice of the invention.

[0103] This document describes preferred embodiments of the invention, including the best modes of carrying out the invention known to the inventors. After reading the foregoing description, variations of those preferred embodiments will be apparent to those skilled in the art. The inventors expect those skilled in the art to appropriately employ these variations, and the inventors intend that the invention be practiced in ways different from those specifically described herein. Therefore, the invention includes all modifications and equivalents of the subject matter described in the appended claims as permitted by applicable law. Furthermore, the invention includes any combination of the foregoing elements in all their possible variations, unless otherwise stated herein or clearly contradicted by the context.

Claims

1. A filter for filtering particles from a fluid flow, the filter comprising: A filter element extending along a longitudinal axis between a first end and a second end, the filter element having an inner surface defining an internal channel and an outer surface defining an outer surface region, the filter element comprising a filter medium made of a non-conductive material; A first end cap and a second end cap are respectively fixed to a first end and a second end of the filter element to form a fluid seal therebetween, wherein at least one of the first end cap and the second end cap defines an opening therethrough, the opening being in fluid communication with the internal passage of the filter element. as well as A wrapping material, the wrapping material being fixed to at least the filter element, the wrapping material comprising a strip having a wrapping material length and a wrapping material width, the wrapping material length being greater than the wrapping material width. The encapsulation comprises a conductive layer and a carrier layer. The conductive layer comprises a conductive material, and the carrier layer is made of a material different from the conductive material. The conductive layer is fixed to the carrier layer. The conductive layer has a conductive layer width, and the carrier layer has a carrier layer width. The conductive layer width is equal to or less than the carrier layer width. The conductive layer is fixed to the carrier layer such that the conductive layer is laterally arranged within or aligned with the carrier layer. The wrapping material is helically wrapped around the filter element to form a plurality of helical windings along the longitudinal axis, such that at least 40 percent of the outer surface area is covered by the conductive layer. The helical windings are spaced apart to define a gap between adjacent helical windings, the wrapping material is helically wrapped around the filter element along a helix angle that is not parallel to a transverse plane perpendicular to the longitudinal axis, the gap has a gap width measured along an axis perpendicular to the helix angle, and the conductive layer width is greater than 40 percent of the sum of the conductive layer width and the gap width.

2. The filter according to claim 1, wherein the conductive layer has a sheet resistance of less than 50 kΩ / sq.

3. The filter according to claim 1 or claim 2, wherein the conductive layer has a tensile strength of at least 90 N along the length of the wrapping.

4. The filter according to claim 1 or claim 2, wherein the conductive material of the conductive layer comprises a permeable nonwoven nylon impregnated with at least one of carbon and a conductive polymer.

5. The filter according to claim 1 or claim 2, wherein, The conductive material of the conductive layer includes a conductive metal.

6. The filter according to claim 1, wherein the width of the conductive layer is within the range of: (1) half the width of the carrier layer and (2) the width of the carrier layer.

7. The filter according to claim 1 or claim 2, wherein the carrier layer is connected to the filter element to resist radial outward expansion of the filter element, and the carrier layer has a tensile strength of at least 90 N along the wrapping length.

8. The filter according to claim 1 or claim 2, wherein the material of the carrier layer comprises a permeable nonwoven polyester.

9. The filter of claim 1 or claim 2, wherein the conductive material of the conductive layer comprises a permeable spunbond nylon impregnated with at least one of carbon and a conductive polymer.

10. The filter according to claim 1 or claim 2, wherein the filter medium comprises at least 99 percent glass fiber by weight.

11. The filter according to claim 1 or claim 2, wherein the filter medium has a basis weight of at least 3 gpsf and at least 4 m 2 / ft 2 Specific surface area.

12. The filter according to claim 1 or claim 2, wherein the filter medium has a first side and a second side, and wherein the filter element includes a first discharge layer disposed on the first side of the filter medium and a second discharge layer disposed on the second side of the filter medium, wherein at least one of the first discharge layer and the second discharge layer comprises a polymer mesh.

13. A fluid filter assembly for filtering particles from a fluid flow, the fluid filter assembly comprising: A housing defining a first port, a second port, and a filter chamber, the first port and the second port communicating with the filter chamber such that a fluid flow path is defined between the first port and the second port through the filter chamber; The filter according to claim 1, The filter is positioned in the filter chamber of the housing such that it lies between the first port and the second port along the fluid flow path, and the filter element is electrically connected to the housing.

14. A method for filtering particles from a fluid stream, the method comprising: The fluid is passed through a filter element of the filter according to claim 1, the fluid having a conductivity of less than 50 pS / m, the filter element extending along a longitudinal axis between a first end and a second end, the filter element having an inner surface defining an internal passage and an outer surface defining an outer surface region; The wrapping material is electrically connected to ground, the wrapping material is fixed to at least the filter element, the wrapping material includes a strip having a wrapping material length and a wrapping material width, the wrapping material length being greater than the wrapping material width, wherein the wrapping material includes a conductive layer comprising a conductive material, and the wrapping material wraps around the filter element such that at least 40 percent of the outer surface area is covered by the conductive layer.

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