Fluid filtration

Abstract

A filter unit, textile treatment device, use, method and apparatus is disclosed. The filter unit comprises a filter housing comprising at least one fluid inlet, at least one fluid outlet and a fluid communication passageway between the fluid inlet(s) and the fluid outlet(s), a rotatable filter cage element within the filter housing that comprises at least one filtering element configured to allow fluid to pass therethrough and to at least partially prevent microfibres from passing therethrough, and at least one strand trapping element within the fluid communication passageway for trapping strand elements present in waste fluid.

Description

[0001] FLUID FILTRATION

[0002] The present invention relates to a filter unit which is capable of filtering microfibres from a waste fluid stream and at the same time is capable of trapping strand elements that are present in the waste fluid stream. In particular, but not exclusively, the present invention relates to a filter unit having a strand trapping device that can catch and hold strands with macroscopic dimensions (such as hair or string) as waste fluid containing the strands pass through the strand trapping device. The trapped strands can then be subsequently removed from the filter unit to help prevent blockage.

[0003] It has been calculated that the global release of microfibres into the Earth’s oceans is around 500,000 tonnes per year. Textile treatments and garment washing produce significant amounts of microfibres which are conventionally simply allowed to exit via the effluent. As an example, it has been determined that a 6Kg wash load can release around 700,000 fibres per wash. Microfibres have been detected across the entire trophic range, in plankton, in fish and estimates indicate that Europeans eat up to 11 ,000 pieces of plastic per year. Microplastics more generally have been detected in rivers, seas, lakes, oceans, ice samples and falling snow across the globe. With this problem in mind, filter units have been developed which help partially or completely remove microfibres from a waste fluid.

[0004] However, it has been observed by the present inventor that filamentous foreign bodies such as human hair or animal hair or string or twine or wire or thread or the like can also be introduced into the filter unit during use (in addition to microfibres). These filamentous foreign bodies may be referred to herein as strand elements. These strand elements may originate from a textile item that is being treated in a textile treatment device such as a washing machine. Once within the filter unit, these strand elements can contribute to blockage of the filter unit and can increase the speed in which a filter unit blocks. Consequently, the strands can adversely affect flow rate through the filter. Due to the elongate and flexible nature of the strands, they also typically become entangled with the inner components of the filter unit making them difficult to remove.

[0005] It is an aim of the present invention to at least partly mitigate one or more of the above- mentioned problems.

[0006] It is an aim of certain embodiments of the present invention to help provide a mechanism for trapping strand elements such that the strand elements are easy to remove from the filter unit. It is an aim of certain embodiments of the present invention to help trap strand elements near a user accessible open mouth such that a user can easily extract the strand elements from the filter unit, for example using their fingers and / or thumb.

[0007] It is an aim of certain embodiments of the present invention to help prevent strand elements from travelling to a location within the filter unit where specialised equipment may be required to remove them.

[0008] It is an aim of certain embodiments of the present invention to help prevent blockage of a filter unit due to strand elements such as hair and string and the like.

[0009] It is an aim of certain embodiments of the present invention to help maintain a desirable flow rate through a filter unit even when many strand elements are trapped for later extraction.

[0010] According to a first aspect of the present invention there is provided a filter unit for filtering microfibres and trapping at least one strand element present in waste fluid, comprising: a filter housing comprising at least one fluid inlet, at least one fluid outlet and a fluid communication passageway between the fluid inlet(s) and the fluid outlet(s); a rotatable filter cage element within the filter housing that comprises at least one filtering element configured to allow fluid to pass therethrough and to at least partially prevent microfibres from passing therethrough; and at least one strand trapping element within the fluid communication passageway for trapping strand elements present in waste fluid.

[0011] Aptly, the function of the or each strand trapping element is to trap at least one of the strand element(s) present in the waste fluid during filtration. Preferably, the majority of strand elements are trapped and especially all strand elements are trapped by the strand trapping element(s) during filtration.

[0012] Aptly, the or each strand trapping element is located upstream of the filtering element(s). Upstream preferably means upstream whilst the filter unit is actively filtering. During filtration fluid is entering the inlet(s) and exiting the outlet(s).

[0013] Aptly, the or each strand trapping element may be part of a strand trapping device located within the filter unit. Aptly, the or each strand trapping element is connected to a fluid conduit body within the filter housing and / or to the rotatable filter cage element and / or to a strand trapping element support member located within the fluid communication passageway.

[0014] Aptly, the fluid conduit body and / or the rotatable filter cage and / or the strand trapping element support member functions as the strand trapping device.

[0015] Aptly, the or each strand trapping element comprises a macroporous fibre matting and / or a plurality of bristle elements and / or at least one protruding element.

[0016] The macroporous fibre matting preferably does not capture microfibres to any appreciable extent. Aptly, a macroporous fibre matting has a pore size of no smaller than 1 mm. Aptly the largest pore size is no greater than 20 mm, or no greater than 10 mm.

[0017] Bristle elements may be in the form of a brush. Aptly, the bristle elements are oriented substantially perpendicular to the flow of the fluid during filtration. By the word substantially 10 or 5 degrees from the perpendicular is included. At least 10, at least 20, at least 50 or at least 100 bristle elements may comprise the strand trapping element(s). The bristles may be arranged in a circular or helical pattern.

[0018] Aptly, the or each strand trapping element is connected to a fluid conduit body within the filter housing, the fluid conduit body comprising a first open mouth at a first body end, for receiving the waste fluid from the fluid inlet, a second open mouth at a second body end, for providing the waste fluid towards the filtering element, and at least one side wall extending between the first body end and the second body end, a fluid flow pathway being provided within the fluid conduit body; wherein the or each strand trapping element is connected to the side wall.

[0019] Aptly, the or each strand trapping element comprises at least one protruding element, extending away from an inner surface of the side wall into the fluid flow pathway.

[0020] Aptly, the or each protruding element extends away from the inner surface in a direction such that an acute angle is formed between the or each protruding element and the inner surface.

[0021] Aptly, the acute angle is in the range of 5 to 85 degrees, and optionally is in the range of 45 to 75 degrees. Aptly, the or each protruding element has a first end region connected to the side wall and a further end region distal from the inner surface of the side wall; and wherein the further end region is closer to the second body end than the first end region.

[0022] Aptly, the or each protruding element has a first end region connected to the side wall and a further end region distal from the inner surface of the side wall; and wherein the further end region is closer to a central longitudinal axis of the fluid conduit body that the first end region.

[0023] Aptly, the or each protruding element has a first end region connected to the side wall and a further end region distal from the inner surface of the side wall; wherein said the or each protruding element has a first surface facing the first open mouth and a second surface facing the second open mouth; and wherein a first distance between the first and second surface at the first end region is greater than a second distance between the first and second surface at the further end region.

[0024] Aptly, the second distance is between 50% and 99% of the first distance.

[0025] Aptly, the first distance is in the range of 2 to 10 mm and wherein the second distance is in the range of 2 to 8 mm.

[0026] Aptly, the further end region comprises an edge where the first and second surface meet.

[0027] Aptly, the first and second surface are substantially flat.

[0028] Aptly, said at least one protruding element is a plurality of protruding elements; and wherein at least one protruding element of the plurality of protruding elements has a first length and at least one other protruding element of the plurality of protruding elements has a second length, greater than the first length.

[0029] Aptly, the first length is between 30% and 99% of the second length.

[0030] Aptly, the first length is in the range of 2 to 10 mm and the second length is in the range of 3 to 6 mm.

[0031] Aptly, the or each protruding element is elongate. Aptly, a width of the or each elongate protruding element is in the range of 2 to 6 mm.

[0032] Aptly, said at least one protruding element comprises at least one pair of protruding elements comprising a first protruding element with a first length and a second protruding element with a second length, greater than the first length.

[0033] Aptly, said at least one protruding element are arranged in groups of three protruding elements. The groups of three protruding elements may be all of the first length or all of the second length, but preferably they comprise a mixture of the first and second length. An especially preferred group of three protruding elements has two of the first length and one of the second length. Preferably, the first length is from 3 to 6 mm and the second length is from 2 to 10mm. Preferably, the protruding element of the second length has a protruding element of the first length on either side. Thus, the group of three protruding elements are preferably arranged in the order first length, second length and then first length.

[0034] Aptly, there may be several groups of three protruding elements. These groups may be present in 2, 3 and especially 4 times. When more than one group of three protruding elements is present these are preferably equally spaced, an especially equally spaced on the side wall or around the inner surface of the side wall.

[0035] Aptly, a nearest distance between the first protruding element and second protruding element is 3 to 6 mm.

[0036] Aptly, the first protruding element and second protruding element are connected to the side wall at a substantially equal distance from the first body end.

[0037] Aptly, said at least one pair of protruding elements comprises a plurality of pairs of protruding elements, said pairs being spaced substantially equally around the inner surface.

[0038] Aptly, an end region of the second protruding element, of the pair of protruding elements, distal from the inner surface is closer to the second body end than an end region of the first protruding element, of the pair of protruding elements, distal the inner surface.

[0039] Aptly, an end region of the second protruding element, of the pair of protruding elements, distal from the inner surface is closer to a central longitudinal axis of the fluid conduit body than an end region of the first protruding element, of the pair of protruding elements, distal the inner surface.

[0040] Aptly, the or each protruding element is connected to the side wall at a position that is closer to the first body end than the second body end.

[0041] Aptly, said the or each protruding element is connected to the side wall at a position within a predefined distance of 6 to 25 mm from the first body end.

[0042] Aptly, the side wall is a substantially cylindrical side wall and the inner surface is a substantially cylindrical radially inner surface.

[0043] Aptly, the side wall contains the waste fluid within the fluid flow pathway in the fluid conduit body.

[0044] Aptly, the fluid conduit body is connected to or integrally formed with the rotatable filter cage.

[0045] Aptly, the fluid conduit body is removable from the rotatable filter cage. Preferred options to provide such removability include for example: twist lock, screw thread, interference fit, magnetic connection, clips, bolts, screws and the like.

[0046] Aptly, the strand trapping element support member is connected to the rotatable filter cage and is removable therefrom. Preferred options to provide such removability include for example: twist lock, screw thread, interference fit, magnetic connection, clips, bolts, screws and the like.

[0047] Aptly, the side wall comprises at least one locating groove comprising a recessed portion on an inner surface of the side wall.

[0048] Aptly, the or each locating groove comprises a first groove portion and a second groove portion, wherein the first groove portion extends from the first body end for a first distance and transitions into the second groove portion which extends from the first groove portion for a second distance. Aptly, in the first groove portion, a width of the locating groove decreases from a maximum at the first body end to a minimum at the transition between the first groove portion and the second groove portion.

[0049] Aptly, the maximum width is in the range of 24 to 30 mm and the minimum width is in the range of 2 to 4 mm.

[0050] Aptly, in the second groove portion, a width of the locating groove is substantially uniform.

[0051] Aptly, a width of the locating groove in the second groove portion is substantially equal to a width of the first groove portion at the transition between the first groove portion and the second groove portion.

[0052] Aptly, the at least one locating groove comprises a plurality of locating grooves, wherein a nearest distance between neighbouring grooves at the first body end is less than 10 mm.

[0053] Aptly, the filter unit further comprises a drive assembly comprising a rotatable drive member that, when rotated, causes rotation of the rotatable filter cage element, and optionally causes rotation of the fluid conduit body.

[0054] Aptly, the rotatable drive member comprises a central body portion and at least one fin element extending away from the central body portion, wherein the or each fin element is sized and shaped for interfacing with a respective locating groove.

[0055] Aptly, the fin element comprises a first major surface, a further, opposed, major surface and an edge region between the first and further opposed major surfaces.

[0056] Aptly, a radial distance from a central longitudinal axis of the central body portion to the edge region continuously increases along a first section of a length of the central body portion.

[0057] Aptly, the radial distance from the central longitudinal axis of the central body portion to the edge region is substantially constant along a second section of the length of the central body portion.

[0058] Aptly, the or each strand trapping element is spaced apart from the rotatable drive member. Aptly, when the fin element is located in a locating groove, the radial distance from the central longitudinal axis of the central body portion to the edge region continuously increases from an axial position proximate the first body end to an axial position where the fin element makes contact with the locating groove.

[0059] Aptly, the drive assembly further comprises a motor and a rotatable shaft element that is connected to the motor and to the rotatable drive member.

[0060] Aptly, the filter unit is configured such that the waste fluid enters the filter housing via the fluid inlet(s), passes the or each strand trapping element and passes through the filtering element(s) of the filter cage before exiting the filter housing via the fluid outlet(s) as filtered fluid.

[0061] Aptly, the waste fluid originates from a waste fluid feed from a textile treatment device.

[0062] Aptly, a plurality of teeth are disposed around an outer surface of the side wall of the fluid conduit body at the second body end, wherein the plurality of teeth are for selectively or permanently coupling to respective recesses located at an end of the filter cage element.

[0063] Aptly, the or each strand element has a longest linear dimension of at least 1 mm, and optionally at least 5 mm and further optionally at least 20 mm.

[0064] Aptly, the or each strand element has a longest linear dimension of no more than 30 cm, or no more than 20 cm or no more than 10 cm.

[0065] The longest linear dimension is preferably the end to end distance when the strand element is disposed in a straight line. A ruler or vernier calliper can be used for this measurement.

[0066] The filter cage element is preferably in the shape of a cylinder although it may alternatively be in the shape of a prism. The filter cage element preferably has one or more apertures where the filtering element(s) may be located. The filtering element(s) may be integral with the rotatable filter cage or they may be separable or removable. The filtering element(s) may be glued, fused, locked, secured or sealed to the filter cage.

[0067] Aptly, the or each strand element has an aspect ratio of longest to shortest dimension in the range of 2:1 to 5,000:1 , or in the range of 10:1 to 5,000:1 . Aptly, the or each strand element comprises human hair or animal hair or string or twine or wire or thread or a combination thereof.

[0068] Aptly, the or each strand element comprises an agglomerated collection of particles or fibres.

[0069] Aptly, any strand element is not a single microfibre.

[0070] Aptly, the filter housing further comprises an opening; and the filter cage element is connected or connectable to a cap that is selectively locatable in the opening to close the opening.

[0071] Aptly, the filter cage element, and optionally the fluid conduit body, is removable from the filter housing upon selective removal of the cap from the opening.

[0072] Microfibres preferably have a linear dimension of smaller than 1 mm, more preferably smaller than 800 microns, smaller than 500 microns and especially smaller than 300 microns. A micron as used herein preferably means 10-6of a metre or a micrometre, typically denoted by the symbol pm.

[0073] For microfibres the linear dimension can be the end to end distance or linear distance if the microfibre adopted a straight or linear shape. The linear dimension can be an average such as for example an arithmetic average. The arithmetic average can be calculated for 100, 1 ,000 or 10,000 microfibres. Optical microscopy optionally with image analysis can suitably provide the linear dimension of the microfibres. Microfibres typically have an aspect ratio of greater than 1 :1 , more preferably greater than 2:1 and especially greater than 5:1. Here the first number denotes the linear dimension and the second number denotes the thickness of the microfibre.

[0074] Microfibres may be natural or synthetic. Preferably, the microfibres originate from a textile, more preferably from the treatment of a textile in a textile treatment device.

[0075] The word fluid as used herein may mean a liquid or a gas, more preferably a liquid. The liquid is preferably aqueous, that is to say the liquid preferably is or comprise water. Other optional liquids which may be present with the water include alcohols, ketones, ethers, esters, aldehydes, amides and the like. Preferably, the waste fluid comprises microfibres. Aptly, the waste fluid comprises at least 0.001 wt%, at least 0.01 wt% or at least 0.1 wt% of microfibres. Aptly, the waste fluid comprises no more than 50wt%, no more than 30wt% or no more than 10wt% of microfibres.

[0076] According to a second aspect of the present invention there is provided a textile treatment device comprising or connected to the filter unit according to the first aspect.

[0077] Aptly, the textile treatment device is a washing machine.

[0078] The textile treatment device may also be a textile finishing machine, a textile bleaching, a textile abrading machine, a textile colouring e.g. (a textile dyeing) machine.

[0079] According to a third aspect of the present invention there is provided use of the filter unit according to the first aspect.

[0080] Aptly the use according to the third aspect is for filtering microfibres and trapping at least one strand element present in a waste fluid.

[0081] According to a fourth aspect of the present invention there is provided use of the textile treatment device according to the second aspect.

[0082] According to a fifth aspect of the present invention there is provided a method of trapping at least one strand element present in waste fluid from a waste fluid feed from a textile treatment device, the method comprising: rotating a filter cage element, located within a filter housing of a microfibre filter unit, comprising at least one filtering element configured to allow fluid to pass therethrough and to at least partially prevent microfibres from passing therethrough, about a longitudinal central axis of the filter cage element; providing waste fluid along a fluid communication passageway from at least one fluid inlet of the filter housing to at least one fluid outlet of the filter housing via the filtering element(s); and via at least one strand trapping element within the fluid communication passageway, trapping strand elements present in the waste fluid in the fluid communication passageway.

[0083] Aptly, the method further comprises providing within the filter housing a fluid conduit body comprising a first open mouth at a first body end, for receiving the waste fluid from the fluid inlet, a second open mouth at a second body end, for providing the waste fluid towards the filtering element, and at least one side wall extending between the first body end and the second body end; and providing the or each strand trapping element as at least one protruding element that extends away from an inner surface of the side wall into a fluid flow pathway provided within the fluid conduit body.

[0084] Aptly, the method further comprises trapping the strand elements in an acutely angled gap formed between the protruding element and the inner surface.

[0085] Aptly, the method further comprises removing the fluid conduit body from the filter housing to allow access to the or each trapped strand element; and separating the or each strand element from the fluid conduit body.

[0086] Aptly, the method further comprises providing the waste fluid from the fluid inlet to the first open mouth.

[0087] Aptly, the method further comprises providing the waste fluid from the second open mouth into an interior of the filter cage element.

[0088] Aptly, the method further comprises rotating the filter cage element simultaneously with the fluid conduit body.

[0089] Aptly, the method further comprises filtering microfibres from the waste fluid as the waste fluid passes through the filtering element.

[0090] Aptly, the method further comprises providing filtered fluid that passes through the filtering element to the fluid outlet.

[0091] Aptly, filtering element(s) are porous, more preferably the filtering element(s) have pores permitting a fluid to pass through the filtering element(s) but to retain microfibres.

[0092] Aptly, the function of the filtering element(s) is to at least partially remove microfibres from the waste fluid.

[0093] Preferably, the filtering elements(s) have a pore size of no more than 1 mm, no more than 800 microns, no more than 600 microns, no more than 400 microns, no more than 300 microns, no more than 200 microns, no more than 150 microns, no more than 125 microns, no more than 100 microns, no more than 90 microns, no more than 80 microns, no more than 70 microns, no more than 60 microns and no more than 55 microns in size.

[0094] Aptly, the filtering element(s) have a pore size of at least 0.1 microns, at least 1 micron or at least 10 microns.

[0095] Preferably, the pore size of the filtering element(s) is from 0.1 to 500 microns, from 0.1 micron to 200 microns, more preferably from 1 micron to 100 microns and especially from 10 microns to 100 microns.

[0096] The size of the pore is preferably measured across the longest linear distance. Optical microscopy optionally together with digital image capture is especially suitable for establishing the size of the pores in the filter medium.

[0097] The filtering element(s) may be any filtering media. Suitable filtering element(s) include a net, a mesh, a perforated screen, a fibre matting and a porous ceramic. Of these, nets and meshes are particularly preferred. Preferably, the filtering element(s) are or comprise a polymeric material, especially nylon.

[0098] Aptly, all of the fluid which enters the filter unit passes through the filtering element(s) during filtration.

[0099] Aptly, the filtering element(s) together with the rotatable filter cage element form a cylinder. Aptly, during filtration fluid from the inlet(s) is directed into the interior of the filter cage element. Aptly, during filtration fluid passes through the filter element(s) in a direction which is from their interior surface to their exterior surface. In this manner filtride (filtered microfibres) are preferably retained on the interior surface of the filtering element(s).

[0100] Aptly, the method further comprises rotating the fluid conduit body via rotating a rotatable drive member comprising a central body portion and at least one fin element that extends away from the central body portion and that is interfaced with at least one respective locating groove on the inner surface of the fluid conduit body.

[0101] According to a sixth aspect of the present invention there is provided apparatus for trapping at least one strand element present in waste fluid from a waste fluid feed from a textile treatment device, comprising: a fluid conduit body comprising a first open mouth at a first body end, a second open mouth at a second body end and at least one side wall extending between the first body end and the second body end, a fluid flow pathway being provided within the fluid conduit body; wherein the fluid conduit body further comprises at least one protruding element, extending away from an inner surface of the side wall into the fluid flow pathway, for trapping strand elements present in waste fluid from a waste fluid feed from a textile treatment device in the fluid flow pathway.

[0102] Aptly, the or each protruding element extends away from the inner surface in a direction such that an acute angle is formed between the or each protruding element and the inner surface.

[0103] Aptly, the acute angle is in the range of 5 to 85 degrees.

[0104] The acute angle is preferably oriented substantially parallel to and in the direction of flow of the fluid during filtration or substantially parallel to and against the direction of flow of the fluid during filtration. Substantially parallel as used directly above preferably means either parallel or within 10, or 5 degrees of being parallel.

[0105] Aptly, the or each protruding element has a first end region connected to the inner surface of the side wall and a further end region distal from the inner surface of the side wall; and wherein the further end region is closer to the second body end of the fluid conduit body than the first end region.

[0106] Aptly, the or each protruding element has a first end region connected to the inner surface of the side wall and a further end region distal from the inner surface of the side wall; and wherein the further end region is closer to a central longitudinal axis of the fluid conduit body that the first end region.

[0107] Aptly, the or each protruding element has a first end region connected to the inner surface of the side wall and a further end region distal from the inner surface of the side wall; wherein said the or each protruding element has a first surface facing the first open mouth and a second surface facing the second open mouth; and wherein a first distance between the first and second surface at the first end region is greater than a second distance between the first and second surface at the further end region. Aptly, the or each protruding element has a first end region connected to the inner surface of the side wall and a further end region distal from the inner surface of the side wall; wherein at least a portion of the first end region is located upstream of the location where the rotatable drive member interfaces with a respective locating groove. Aptly, the distance between the most upstream point of the first end region and the most upstream point of the location where the rotatable drive member interfaces with a respective locating groove is preferably at least 1 mm, more preferably at least 2 mm and especially at least 3 mm, preferably being no more than 20 mm or no more than 10 mm, preferably this distance is measured along a line parallel to the axis of rotation of the filter cage element. These preferences have been found to assist in inhibiting the wrapping of strand elements around the rotatable drive member and / or to assist in the elongate protrusions removing strand elements from the drive member when the filter cage element is removed from the filter housing for emptying or cleaning.

[0108] Aptly, the first distance is in the range of 2 to 10 mm and wherein the second distance is in the range of 2 to 8 mm.

[0109] Aptly, the second distance is between 50% and 99% of the first distance.

[0110] Aptly, the further end region comprises an edge where the first and second surface meet.

[0111] Aptly, the first and second surface are substantially flat.

[0112] Aptly, said at least one protruding element is a plurality of protruding elements; and wherein at least one protruding element of the plurality of protruding elements has a first length and at least one other protruding element of the plurality of protruding elements has a second length, greater than the first length.

[0113] Aptly, the first length is in the range of 2 to 10 mm and the second length is in the range of 3 to 6 mm.

[0114] Aptly, the or each protruding element is elongate.

[0115] Aptly, a width of the or each elongate protruding element is in the range of 2 to 6 mm. Aptly, said at least one protruding element comprises at least one pair of protruding elements comprising a first protruding element with a first length and a second protruding element with a second length, greater than the first length.

[0116] Aptly, a nearest distance between the first protruding element and second protruding element is 3 to 6 mm.

[0117] Aptly, the first protruding element and second protruding element are connected to the side wall at a substantially equal distance from the first body end.

[0118] Aptly, said at least one pair of protruding elements comprises a plurality of pairs of protruding elements, said pairs being spaced substantially equally around the inner surface.

[0119] Aptly, an end region of the second protruding element, of the pair of protruding elements, distal from the inner surface is closer to the second body end than an end region of the first protruding element, of the pair of protruding elements, distal the inner surface.

[0120] Aptly, an end region of the second protruding element, of the pair of protruding elements, distal from the inner surface is closer to a central longitudinal axis of the fluid conduit body than an end region of the first protruding element, of the pair of protruding elements, distal the inner surface.

[0121] Aptly, the or each protruding element is connected to the side wall at a position that is closer to the first body end than the second body end.

[0122] Aptly, said the or each protruding element is connected to the side wall at a position within a predefined distance of 6 to 25 mm from the first body end.

[0123] Aptly, the side wall is a substantially cylindrical side wall and the inner surface is a substantially cylindrical radially inner surface.

[0124] Aptly, the side wall contains the waste fluid within the fluid flow pathway in the fluid conduit body.

[0125] Aptly, the inner surface of the side wall comprises at least one locating groove sized and shaped to interface with at least one respective fin element of a rotatable drive member. Aptly, the or each locating groove comprises a recessed portion of the inner surface.

[0126] Aptly, the or each locating groove comprises a first groove portion and a second groove portion, wherein the first groove portion extends from the first body end for a first predetermined distance and transitions into the second groove portion which extends from the first groove portion for a second predetermined distance.

[0127] Aptly, in the first groove portion, a width of the locating groove decreases from a maximum at the first body end to a minimum at the transition between the first groove portion and the second groove portion.

[0128] Aptly, the maximum width is in the range of 24 to 30 mm and the minimum width is in the range of 2 to 4 mm.

[0129] Aptly, in the second groove portion, a width of the locating groove is substantially uniform.

[0130] Aptly, a width of the locating groove in the second groove portion is substantially equal to a width of the first groove portion at the transition between the first groove portion and the second groove portion.

[0131] Aptly, the at least one locating groove comprises a plurality of locating grooves, wherein a nearest distance between neighbouring grooves at the first body end is less than 10 mm.

[0132] Aptly, the rotatable drive member comprises a central body portion and at least one fin element extending away from the central body portion, wherein the or each fin element is sized and shaped for interfacing with a respective locating groove.

[0133] Aptly, the fin element comprises a first major surface, a further, opposed, major surface and an edge region between the first and further opposed major surfaces.

[0134] Aptly, a radial distance from a central longitudinal axis of the central body portion to the edge region continuously increases along a first section of a length of the central body portion.

[0135] Aptly, the radial distance from the central longitudinal axis of the central body portion to the edge region is substantially constant along a second section of the length of the central body portion. Aptly, when the fin element is located in a locating groove, the radial distance from the central longitudinal axis of the central body portion to the edge region continuously increases from an axial position proximate the first open body end to an axial position where the fin element makes contact with the locating groove.

[0136] Aptly, a plurality of teeth are disposed around an outer surface of the side wall at the second body end, wherein the plurality of teeth are for selectively or permanently coupling to respective recesses located at an end of a filter cage element.

[0137] Aptly, the or each strand element has a longest linear dimension of at least 1 mm, and optionally at least 5 mm and further optionally at least 20 mm.

[0138] Aptly, the or each strand element has an aspect ratio of longest to shortest dimension in the range of 2:1 to 5,000:1 , or in the range 10:1 to 5,000:1 .

[0139] Aptly, the or each strand element comprises human hair or animal hair or string or twine or wire or thread or a combination thereof.

[0140] Aptly, the or each strand element comprises an agglomerated collection of particles or fibres.

[0141] Aptly, any strand element is not a single microfibre.

[0142] According to a seventh aspect of the present invention there is provided a filter unit for filtering microfibres comprising the apparatus of the sixth aspect.

[0143] According to an eighth aspect of the present invention there is provided use of the apparatus according to the sixth aspect.

[0144] All features, options and preferences expressed in relation to items as described in the first aspect of the present invention are equally applicable to all other aspects of the invention unless otherwise stated or unless incompatible.

[0145] Certain embodiments of the present invention help provide a filter unit in which microfibres can be filtered from waste fluid and which can also trap strand elements such as hair or string (which are not microfibres) present in the waste fluid for later extraction from the filter unit. Certain embodiments of the present invention help provide a mechanism for easy removal of strand elements from a filter unit.

[0146] Certain embodiments of the present invention help trap strand elements in a waste fluid stream within a fluid communication passageway of a filter unit without adversely affecting fluid flow rate.

[0147] Embodiments of the present invention will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which:

[0148] Figure 1 illustrates a perspective view of a washing machine including a filter unit;

[0149] Figure 2 illustrates a top view of the washing machine of Figure 1 ;

[0150] Figure 3 illustrates the filter unit shown in Figures 1 and 2;

[0151] Figure 4 illustrates certain components that are removable from a filter housing of a filter unit;

[0152] Figure 5 illustrates a rotatable filter cage connected to a stand trapping device and interfaced with part of a drive assembly;

[0153] Figure 6 illustrates a cross-section of the assembly shown in Figure 5;

[0154] Figure 7 illustrates an interface between a drive assembly and a strand trapping device;

[0155] Figure 8 illustrates a side view of a strand trapping device;

[0156] Figure 9 illustrates a cross-sectional profile of the device of Figure 8;

[0157] Figure 10 illustrates a top view of the device shown in Figure 8;

[0158] Figure 11 illustrates a further top view of half of the device shown in Figure 8;

[0159] Figure 12 illustrates a magnified view of strand trapping elements in the form of hooks; Figure 13 illustrates a cross-sectional view of a strand trapping element (hook) showing how an acute angle is formed;

[0160] Figure 14 illustrates a top view of a strand trapping device when interfaced with a drive assembly;

[0161] Figure 15 illustrates a bottom view of a strand trapping device when interfaced with a drive assembly;

[0162] Figure 16 illustrates a perspective view of a strand trapping device when interfaced with a drive assembly;

[0163] Figure 17 illustrates a further perspective view of a strand trapping device when interfaced with a drive assembly;

[0164] Figure 18 illustrates a rotatable drive member of a drive assembly;

[0165] Figure 19 illustrates a bottom view of the drive member of Figure 18;

[0166] Figure 20 illustrates a rotatable filter cage connected to a strand trapping device;

[0167] Figure 21 illustrates a side view the strand trapping device shown in Figure 20;

[0168] Figure 22 illustrates a top view of the strand trapping device shown in Figure 20; and

[0169] Figure 23 illustrates a top view of a further strand trapping device.

[0170] In the drawings like reference numerals refer to like parts.

[0171] Figures 1 and 2 illustrate a washing machine 100 including a filter unit 110. It will be appreciated that according to other embodiments, the filter unit could be included within other textile treatment devices such as a textile finishing machine, a textile bleaching, a textile abrading machine, a textile colouring e.g. (a textile dyeing) machine. It will also be appreciated that in other embodiments the filter unit may not be incorporated within the textile treatment device but may be separate from the textile treatment device and fluidly connected thereto. The washing machine has a drum located within a tub 120, an inlet pipe 130 leading from the tub to a fluid inlet 140 of the filter unit, and an outlet pipe 150 leading from the fluid outlet 160 of the filter unit back to the tub and / or to an external drain opening (not shown). It will be appreciated that the filter unit may have more than one fluid inlet and more than one fluid outlet. As is best illustrated in Figure 1 , the filter unit 110 is located within a drawer of the washing machine next to a detergent compartment 170. In use, waste fluid is directed from the tub by means of a pump along the inlet pipe into the fluid inlet of the filter unit. The filter unit then filters microfibres and strand elements from the waste fluid before allowing filtered fluid to pass out of the fluid outlet of the filter unit.

[0172] Figure 3 illustrates the filter unit 110 shown in Figures 1 and 2. The filter unit includes a filter housing 210 including the fluid inlet 140 and the fluid outlet 160. A fluid communication passageway (not shown) extends between the fluid inlet and the fluid outlet. The fluid communication passageway encompasses all areas of the interior of the filter housing that are in fluid communication. In other words, the filter housing defines an internal fluid chamber within which fluid is contained and the fluid communication passageway is defined by this internal fluid chamber. The filter unit also includes a rotatable filter cage 220 and a motor 230. During use, the motor causes rotation of a shaft 240 which is attached to a coupler 250. Consequently, the coupler rotates about a longitudinal axis of rotation of the rotating shaft. The coupler helps to account for imperfect rotation about an axis of rotation. The other side of the coupler is attached to a rotatable shaft element 260 which is connected to a rotatable drive member (not shown in Figure 3). Rotation of the drive member causes rotation of the filter cage 220. The motor, shaft, coupler, rotatable drive shaft and rotatable drive member together form a drive assembly of the filter unit. Figure 3 also illustrates how a cap 270 is selectively located in an end opening of the filter housing. The cap may be a twist lock cap. The cap is connected to the filter cage such that removal of the cap causes removal of the filter cage and the strand trapping device (not shown in Figure 3) so that microfibres caught by the filter cage and strand elements trapped by the trapping device can be placed into a bin.

[0173] Figure 4 illustrates components which are removable from a filter housing during cleaning of the filter unit. This includes a cap 410, a filter cage 420 and a strand trapping device 430. The filter cage 420 includes a series of holes in which filter elements 425 are placed. A single filtering element or multiple filtering elements could be used. The filtering elements allow fluid to pass through them but prevent the passage of microfibres at least to some extent. The filtering elements can be secured to the ribs of the filter cage according to any suitable means. The filter cage and strand trapping device may be integrally formed or may be connected together by any suitable means. In other embodiments, the filter cage and strand trapping device may be spaced apart from each other. It will also be appreciated that whilst in Figure 4 the strand trapping device is used to trap strands, the strand trapping mechanism may be built into the filter cage itself.

[0174] In use, waste fluid originating from a textile treatment device such as a washing machine enters the strand trapping device from the fluid inlet of the filter housing. The waste fluid may contain microfibres as well as strand elements. In the strand trapping device, at least some or all of the strands present in the waste fluid are trapped and prevented from entering the filter cage. For example, the strand elements may be trapped on hooked protruding elements extending from an inner surface of the strand trapping device into the flow pathway and / or may be trapped by a macroporous fibrous matting extending across the flow pathway within the strand trapping device and / or may be trapped by bristle elements (i.e., a brush-like arrangement) extending from the inner surface of the strand trapping device into the flow pathway. Once trapped, the strand elements can then be removed at a later time (e.g., once the treatment cycle is complete). The waste fluid continues from the strand trapping device into the interior of the filter cage which is rotating. Centrifugal force causes the waste fluid to be directed towards the inner surface of the filter cage wherein fluid is able to pass though the filtering elements of the filter cage whilst microfibres are totally or partially held within the interior of the filter cage. The filtered fluid can then exit via the fluid outlet of the filter housing. In the example of Figure 4, the strand trapping device also rotates as the waste fluid passes through it. However, it will be appreciated that according to other embodiments the strand trapping device may be stationary (i.e., does not rotate) whilst the waste fluid passes through it.

[0175] Figure 5 illustrates a side view of a filter cage 510 with a rotatable drive member 520 engaged therein. In Figure 5, the cap has been disengaged from the end wall of the filter cage and the end wall (which is connected to the filter cage via a screw thread) has also been removed. Figure 6 illustrates a cross-sectional view of the components shown in Figure 5. As can be seen, the drive member 520 has a central body 610 and a series of fins 620 which extend radially outwardly therefrom. The fins are located in locating grooves 630 (see Figure 7) such that rotation of the drive member causes rotation of the strand trapping device and consequently rotation of the rotatable filter cage.

[0176] The central body of the drive member is hollowed out with a recess which has a size and shape to enable a mating connection to be made with the rotatable shaft. The end of the shaft may include a female threaded portion into which a male fixing element (such as a screw or bolt or the like) can be fixed. The fixing element extends through an opening in the top of the central body of the drive member and into the hollowed out recess where it can be securely fixed to the drive shaft.

[0177] Figure 8 illustrates a strand trapping device in isolation. The device is a fluid conduit body 800. The fluid conduit body has a first open mouth at a first body end 810 and a second open mouth at a second body end 820. A side wall 830 extends between the two body ends. A fluid flow pathway is provided within the conduit body. The first open mouth is positioned in the filter unit such that waste fluid entering the filter housing via the fluid inlet passes into the conduit body via the first open mouth. After leaving the conduit body via the second open mouth, the waste fluid is directed towards an interior of the filter cage. Whilst the conduit body in Figure 8 has an approximately circular cross-section, it will be appreciated that in other embodiments other cross-sectional shapes (triangular, square or the like) may be used. The fluid conduit body has a series of teeth 840 at the second body end to enable a connection to be made with the filter cage.

[0178] Figure 9 illustrates a cross-sectional profile 900 of the fluid conduit body of Figure 8. As can be seen, the fluid conduit body has a series of pairs of protruding elements 910. Each of the pairs has two protruding elements 920 that extend from an inner surface of the side wall into the fluid flow pathway (a close up of a pair is shown in Figure 12). Each protruding element is an example of a strand trapping element. In this embodiment, the protruding elements may be referred to as hooks. The protruding elements each extend from the side wall in a direction towards the second open mouth (and thus away from the first open mouth). An acute angle is formed between the protruding elements and the side wall (best seen in Figure 13) and this acute angle helps to enable strand elements to be trapped within the fluid flow pathway. As can be seen in Figure 9, one of the protruding elements of each pair is closer to the second body end than the first body end. Likewise, as is shown in Figures 10 and 11 , for each pair, one of the protruding elements is closer to a central longitudinal axis of the conduit body than the other. Offsetting the protruding elements in this way helps to ensure that strand elements that might be missed by one of the protruding elements is trapped by the other protruding element. It will be appreciated that pairs of protruding elements are not needed and that any number of protruding elements can be used. In Figures 9-13, the protruding elements are elongate. However, it will be appreciated that according to certain embodiments, the protruding elements can extend partially or fully along the inner surface of the fluid conduit body to provide a greater width to the protruding element (such as is shown in Figure 23). Figure 9 also helps to illustrate a locating groove 930. The fluid conduit body may have any suitable number of locating grooves according to the number of fins on the rotatable drive member. Each locating groove may have a first groove portion 940 and a second groove portion 950. The first groove portion has a maximum width at the first body end and a minimum width where the two groove portions meet. The second groove portion has a uniform width. At the first body end, an edge of one locating groove is immediately adjacent an edge of a neighbouring locating groove. In this way, the fins of the drive member can be mated with the locating grooves without having to first orient the two components correctly with respect to one another. This is beneficial as this mating takes place at a location within the filter housing where visible inspection is difficult.

[0179] Figures 14-17 illustrate various views of a rotatable drive member in position within a strand trapping device, showing how rotation of the drive member would cause rotation of the strand trapping device (and thus the filter cage that is connected to that device). It will be appreciated that according to other embodiments, a drive member may not be needed and rotation of the relevant components may be achieved by providing a baffle surface that results in rotational motion when fluid is directed towards the baffle surface.

[0180] Turning to Figure 18, a rotatable drive member 1800 is showed in isolation. As can be seen, each of the fin elements has a first and further major surface 1810, 1820 with an edge region 1830 therebetween. There is a portion 1840 of the edge region where the radial distance from the central longitudinal axis of the central body continuously increases. This continuous increase is helpful as, when the drive member is in position, it helps to cause strands to be directed towards the strand trapping elements. There is also a portion 1850 of the edge region where the radial distance is substantially constant. This is helpful to ensure a good contact is established with the locating groove. Figure 19 helps illustrate how an end 1860 of the central body is recessed and has a truncated circular shape corresponding to a shape of a shaft element.

[0181] Figure 20 illustrates a filter cage connected to a strand trapping device according to an alternative embodiment. In particular, in Figure 20, the strand trapping device is also a fluid conduit body (like in Figure 8) but instead of having hooks the conduit body includes a series of bristle elements 2010 which extend from an inner surface of the side wall. These bristle elements together form a brush-like region where strands may be trapped. Each bristle element is another example of a strand trapping element. Figures 21 and 22 show a side view and top view, respectively, of the fluid conduit body which is shown attached to the filter cage shown in Figure 20.

[0182] Whilst in the embodiments described herein, the strand trapping elements have been shown as extending inwardly from a side wall of a fluid conduit body, it will be appreciated that they may alternatively extend inwardly from the filter cage and / or from an outer surface of a support member that is disposed in the fluid communication passageway specifically to hold the strand capturing elements. It will also be appreciated that a combination of strand trapping elements may be used (e.g., hooks, bristles, macroporous fibre mattings and the like may all be used separately or in any combination thereof).

[0183] The present inventor carried out experiments to test how the flow rate of fluid passing through a filter unit having a strand trapping device was affected by the introduction of lengths of string (strand elements) into the fluid. The present inventor found that the use of strand trapping elements (e.g., hooks) worked effectively and provided a method of trapping / catching strand elements. Offset hooks helped provide a larger surface area or area of contact for string or long fibres to be caught on, providing a ‘fail-safe’ to reduce the likelihood of blockage within the filter unit. Using collected flow rate data (see Table 1 ), the present inventor observed a minimal change in the flow rate. It was hypothesised that discrepancies in the data could be the result of human error due to the method of testing (measuring collected volume over a set time period). The evidence in Table 1 demonstrates that strand elements that are trapped within the filter unit do not have a negative effect on the flow rate and that the strand trapping devices discussed herein do not have any detrimental effect on the function of a filter unit.

[0184] Table 1

[0185] String length (cm) Quantity Run time (Intervals) Flow rate (Lmin-1 )

[0186] ~7 0 2 20.4

[0187] ~7 5 2 19.8

[0188] ~7 10 2 19.5

[0189] ~7 15 2 18.6

[0190] ~7 20 2 18

[0191] ~7 20 5 19.2

[0192] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to” and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0193] Features, integers, characteristics or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of the features and / or steps are mutually exclusive. The invention is not restricted to any details of any foregoing embodiments. The invention extends to any novel one, or novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0194] The reader’s attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

CLAIMS:1 . A filter unit for filtering microfibres and trapping at least one strand element present in waste fluid, comprising: a filter housing comprising at least one fluid inlet, at least one fluid outlet and a fluid communication passageway between the fluid inlet(s) and the fluid outlet(s); a rotatable filter cage element within the filter housing that comprises at least one filtering element configured to allow fluid to pass therethrough and to at least partially prevent microfibres from passing therethrough; and at least one strand trapping element within the fluid communication passageway for trapping strand elements present in waste fluid.

2. The filter unit as claimed in claim 1 , wherein: the or each strand trapping element is located upstream of the filtering element(s).

3. The filter unit as claimed in claim 1 or claim 2, wherein: the or each strand trapping element is connected to a fluid conduit body within the filter housing and / or to the rotatable filter cage element and / or to a strand trapping element support member located within the fluid communication passageway.

4. The filter unit as claimed in claim 3, wherein: the or each strand trapping element comprises a macroporous fibre matting and / or a plurality of bristle elements and / or at least one protruding element.

5. The filter unit as claimed in claim 3 or claim 4, wherein: the or each strand trapping element is connected to a fluid conduit body within the filter housing, the fluid conduit body comprising a first open mouth at a first body end, for receiving the waste fluid from the fluid inlet, a second openmouth at a second body end, for providing the waste fluid towards the filtering element, and at least one side wall extending between the first body end and the second body end, a fluid flow pathway being provided within the fluid conduit body; wherein the or each strand trapping element is connected to the side wall.

6. The filter unit as claimed in claim 5, wherein: the or each strand trapping element comprises at least one protruding element, extending away from an inner surface of the side wall into the fluid flow pathway.

7. The filter unit as claimed in claim 6, wherein: the or each protruding element extends away from the inner surface in a direction such that an acute angle is formed between the or each protruding element and the inner surface.

8. The filter unit as claimed in claim 7, wherein: the acute angle is in the range of 5 to 85 degrees, and optionally is in the range of 45 to 75 degrees.

9. The filter unit as claimed in any one of claims 6 to 8, wherein: said at least one protruding element is a plurality of protruding elements; and wherein at least one protruding element of the plurality of protruding elements has a first length and at least one other protruding element of the plurality of protruding elements has a second length, greater than the first length.

10. The filter unit as claimed in any one of claims 6 to 9, wherein: the or each protruding element is elongate.11 .The filter unit as claimed in any one of claims 6 to 10, wherein:said at least one protruding element comprises at least one pair of protruding elements comprising a first protruding element with a first length and a second protruding element with a second length, greater than the first length.

12. The filter unit as claimed in claim 1 1 , wherein: said at least one pair of protruding elements comprises a plurality of pairs of protruding elements, said pairs being spaced substantially equally around the inner surface.

13. The filter unit as claimed in any one of claims 6 to 12, wherein: the or each protruding element is connected to the side wall at a position that is closer to the first body end than the second body end.

14. The filter unit as claimed in any one of claims 6 to 13, wherein: the side wall comprises at least one locating groove comprising a recessed portion on an inner surface of the side wall.

15. The filter unit as claimed in claim 14, wherein: the or each locating groove comprises a first groove portion and a second groove portion, wherein the first groove portion extends from the first body end for a first distance and transitions into the second groove portion which extends from the first groove portion for a second distance.

16. The filter unit as claimed in claim 15, wherein: in the first groove portion, a width of the locating groove decreases from a maximum at the first body end to a minimum at the transition between the first groove portion and the second groove portion.

17. The filter unit as claimed in claim 15 or claim 16, wherein: in the second groove portion, a width of the locating groove is substantially uniform.

18. The filter unit as claimed in any preceding claim, further comprising:a drive assembly comprising a rotatable drive member that, when rotated, causes rotation of the rotatable filter cage element, and optionally causes rotation of the fluid conduit body as claimed in any one of claims 6 to 17.

19. The filter unit as claimed in claim 18, wherein: the rotatable drive member comprises a central body portion and at least one fin element extending away from the central body portion, wherein the or each fin element is sized and shaped for interfacing with a respective locating groove as claimed in any one of claims 14 to 17.

20. The filter unit as claimed in claim 19, wherein: the fin element comprises a first major surface, a further, opposed, major surface and an edge region between the first and further opposed major surfaces.21 .The filter unit as claimed in claim 20, wherein: a radial distance from a central longitudinal axis of the central body portion to the edge region continuously increases along a first section of a length of the central body portion.

22. The filter unit as claimed in claim 21 , wherein: the radial distance from the central longitudinal axis of the central body portion to the edge region is substantially constant along a second section of the length of the central body portion.

23. The filter unit as claimed in any preceding claim, wherein: the filter unit is configured such that the waste fluid enters the filter housing via the fluid inlet(s), passes the or each strand trapping element and passes through the filtering element(s) of the filter cage before exiting the filter housing via the fluid outlet(s) as filtered fluid.

24. The apparatus as claimed in any preceding claim, wherein:the or each strand element comprises human hair or animal hair or string or twine or wire or thread or a combination thereof.

25. A textile treatment device comprising or connected to the filter unit as claimed in any preceding claim, wherein optionally the textile treatment device is a washing machine.

26. Use of the filter unit as claimed in any one of claims 1 to 24 or use of the textile treatment device as claimed in claim 25.

27. A method of trapping at least one strand element present in waste fluid from a waste fluid feed from a textile treatment device, the method comprising: rotating a filter cage element, located within a filter housing of a microfibre filter unit, comprising at least one filtering element configured to allow fluid to pass therethrough and to at least partially prevent microfibres from passing therethrough, about a longitudinal central axis of the filter cage element; providing waste fluid along a fluid communication passageway from at least one fluid inlet of the filter housing to at least one fluid outlet of the filter housing via the filtering element(s); and via at least one strand trapping element within the fluid communication passageway, trapping strand elements present in the waste fluid in the fluid communication passageway.

28. The method as claimed in claim 27, further comprising: providing within the filter housing a fluid conduit body comprising a first open mouth at a first body end, for receiving the waste fluid from the fluid inlet, a second open mouth at a second body end, for providing the waste fluid towards the filtering element, and at least one side wall extending between the first body end and the second body end; and providing the or each strand trapping element as at least one protruding element that extends away from an inner surface of the side wall into a fluid flow pathway provided within the fluid conduit body.

29. The method as claimed in claim 28, further comprising: trapping the strand elements in an acutely angled gap formed between the protruding element and the inner surface.

30. The method as claimed in claim 28 or claim 29, further comprising: rotating the filter cage element simultaneously with the fluid conduit body.

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