Filter apparatus

Abstract

The present disclosure relates to a filter unit for filtering debris from debris-laden liquid. The filter unit comprises: a housing at least partly defining a filtering cavity, the housing comprising a perforated wall portion forming the base of the filtering cavity for accumulation of debris in a filtering configuration; and a debris collection chamber in communication with the filtering cavity via a debris port. The filter unit is airtight above the perforated wall portion in at least the filtering configuration and wherein at least an opening from the filtering cavity into the debris port is above the perforated wall portion.

Description

[0001] FILTER APPARATUS

[0002] Field of the Disclosure

[0003] The present disclosure relates to a filter unit for the separation of debris from debris-laden fluid e.g. liquid or air, and in particular to a filter unit that can be easily fitted or retrofitted to existing washing or drying appliances or can be used in water treatment apparatus. The present disclosure also relates to a method of using the filter unit.

[0004] Background

[0005] Textile and fabric processing and washing appliances, both domestic and commercial, usually use water containing chemicals such as detergent to wash or condition the textile and fabric items. During the washing process, micro-fibres and micro-particles from the textile / fabric items being washed are often created. These micro-fibres and micro-particles enter the water and, at the end of the washing cycle, are ejected together with the dirty water, from the appliance.

[0006] There is a growing concern about the effect of these micro-fibers and micro-particles on our environment as they end up entering the water cycle and contaminating rivers and seas. It is estimated that a typical domestic washing machine can generate around 700,000 microscopic fibers for each wash.

[0007] Filter units using a perforated mesh for filtering debris from waste washing water are known but the perforated mesh quickly become blocked thus requiring frequent cleaning of the mesh which is inconvenient.

[0008] WO2021 / 191215 describes a filter unit where accumulated debris is collected on an unperforated peripheral particle collection wall within a rotatable chamber by centrifugal force and then subsequently discharged from within the chamber under gravity via a particle dispense opening. However, the accumulated debris, especially where it contains washing powder residue, can become compacted against the particle collection wall thus making it difficult to remove. It is also not straight forward to remove the discharged debris from within the washing appliance once discharged from the filter unit. The WO’215 filter is also of a size and cost that make it undesirable for incorporation by manufacturers of washing appliances.

[0009] Micro-fibers and micro-particles from textiles are also created during drying and these have to be filtered from the air before it is discharged from the dryer. Most drying applicants have a mesh filter through which air is passed and which collects the fluff and the lint. These filters require regular cleaning to ensure optimal dryer and to avoid damage to the appliance.

[0010] Waste water processing e.g. processing of commercial and residential effluent / sewage requires separation of particulates from the water. This is often effected in settlement tanks where solids sink to the bottom. The water is separated from the sludge and filtered through a filter medium e.g. sand. These processes are timing consuming and require large volume settlement tanks.

[0011] There is a desire to develop a filter unit that can reduce the above problems.

[0012] Summary

[0013] According to a first aspect, there is provided a filter unit for filtering debris from debris-laden liquid, the filter unit comprising: a housing at least partly defining a filtering cavity, the housing comprising a perforated wall portion forming the base of the filtering cavity for accumulation of debris in a filtering configuration, a debris collection chamber in communication with the filtering cavity via a debris port, wherein the filter unit is airtight above the perforated wall portion in at least the filtering configuration, and wherein at least an opening from the filtering cavity into the debris port is above the perforated wall portion.

[0014] By providing a filter unit which is airtight above a perforated wall portion in the filtering configuration, it is possible to flow debris-laden liquid into the filtering cavity for filtering through the perforated wall portion at the base of the filtering cavity and to form an air pocket above the liquid / perforated wall portion. The opening of the debris port is provided above the perforated wall portion i.e. is within the air pocket in the filtering configuration so that no liquid can enter the debris collection chamber via the debris port from the filtering cavity. This ensures that no collected debris is re-entrained in the liquid (even though the debris port can remain open to the filtering cavity even in the filtering configuration) and allows any collected debris within the debris collection chamber to dry out / remain dry to reduce the likelihood of bacterial growth within the collected debris. It therefore becomes only necessary to empty the debris collection chamber when it becomes full. It can thus be appreciated that the disclosed filter unit reduces the frequency of the removal of collected debris from the filter unit and thus improves user experience. Furthermore, the airtight nature of the filter unit in the filtering configuration means that the pressure imparted to the debris-laden liquid as it is pumped into the filter unit is retained which helps force the liquid through the perforated wall portion thus increasing the flow rate through the filter.

[0015] Throughout this disclosure, the term “above” is used with reference to the filter unit oriented with the perforated wall portion defining the lowermost portion (i.e. the base) of the filtering cavity. As such, the term “above the perforated wall portion” means “spaced vertically higher than the perforated wall portion” or “spaced from the perforated wall in a vertical direction”.

[0016] The filter unit is airtight above the perforated wall portion in the filtering configuration i.e. there is no air flow path into the filtering cavity in the filtering configuration. There are no air inlets / outlets opening from the filtering cavity externally to the filter unit in the filtering configuration. This allows the formation of an air pocket above the perforated wall portion in the filtering configuration. At least the opening of the debris port is provided in the air pocket.

[0017] There may be an air flow path (e.g. an air bleed) into the filtering cavity when the filter unit is not in the filtering configuration as discussed below.

[0018] Optional features of the first aspect will now be set out. These are applicable singly or in any combination.

[0019] In some embodiments of the first aspect, the debris port and / or the debris collection chamber is above (i.e. spaced vertically higher than) the perforated wall portion in at least the filtering configuration. The debris collection chamber is preferably disposed at least partly above the debris port. The debris port and / or debris collection chamber may be provided in the air pocket formed in the filtering configuration.

[0020] In some embodiments of the first aspect, the filter unit further comprises at least one wiper mounted within the filtering cavity for wiping the perforated wall portion.

[0021] In some embodiments of the first aspect, the filter unit has a transfer configuration in which the at least one wiper is rotatable for transferring accumulated debris from the filtering cavity to the debris collection chamber (via the debris port).

[0022] In some embodiments of the first aspect, the at least one wiper is rotatable at a first rotation speed and at a second rotation speed. The second rotation speed may be greater than the first rotation speed.

[0023] In some embodiments of the first aspect, the at least one wiper is rotatable at a filtering rotation speed in the filtering configuration and at a transfer rotation speed in the transfer configuration. The transfer rotation speed may be greater than the filtering rotation speed.

[0024] In some embodiments of the first aspect, the at least one wiper is rotatable in a first (e.g. filtering) rotation direction and in a second (e.g. transfer) rotation direction. The second rotation direction may be different to the first rotation direction.

[0025] In some embodiments of the first aspect, the at least one wiper may comprise a compliant wiping portion for wiping the perforated wall portion.

[0026] In some embodiments of the first aspect, the at least one wiper is rotatable in the first rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion. The at least one wiper may be rotatable in an opposing second rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion. The first contact surface of the wiping portion may have a different area than the second contact surface of the wiping portion.

[0027] In some embodiments of the first aspect, the first rotation direction is a filtering rotation direction and is effected in the filtering configuration with the wiping portion flexed in the first flex direction during filtering.

[0028] In some embodiments of the first aspect, the second rotation direction is a transfer rotation direction effected in the transfer configuration with the wiping portion flexed in the opposing second flex direction for transferring accumulated debris from the filtering cavity to the debris collection chamber.

[0029] In some embodiments, the first contact surface area is less than the second contact surface area.

[0030] In some embodiments of the first aspect, the debris collection chamber is moveable (e.g. one or more of slidable, pivotable and liftable) relative to the housing (e.g. removable from the housing) in an emptying configuration.

[0031] According to a second aspect, there is provided a filter unit for filtering debris from debris-laden fluid / liq uid , the filter unit comprising: a housing at least partly defining a filtering cavity, the housing comprising a perforated wall portion for accumulation of debris, at least one wiper mounted within the filtering cavity for wiping the perforated wall portion, a debris collection chamber in communication with the filtering cavity via a debris port, wherein the filter unit has a filtering configuration in which the at least one wiper is rotatable at a filtering rotation speed; wherein the filter unit has a transfer configuration in which the at least one wiper is rotatable at a transfer rotation speed for transferring accumulated debris from the filtering cavity to the debris collection chamber; and wherein the debris collection chamber is moveable relative to the housing in an emptying configuration.

[0032] The inventors have found that by providing at least one wiper that is rotatable at a filtering speed for wiping the perforated wall portion, debris accumulated on the particle collection wall as debris-laden fluid / liq uid (e.g. waste (washing) water or drying air) flows through the filter unit can be agglomerated by the shearing action of the wiper against the perforated wall portion. The agglomerated debris tends to remain suspended within the fluid / liquid in the filtering cavity rather than blocking the perforated wall portion and thus the filtering capability of the perforated wall portion is prolonged. After filtering is complete (e.g. at the end of a wash or rinse cycle of a washing appliance, the end of a drying cycle or the end of waste water filtering), the wiper can be rotated at the transfer rotation speed (which may be faster than the filtering rotation speed) to transfer the accumulated debris into the debris collection chamber. This removal of debris from the filtering cavity (by the wiper blade) can be achieved without having to open the filtering cavity (thus reducing the number of seals required in the filtering unit) and without user input thus improving the user experience.

[0033] When needed (e.g. when the debris collection chamber becomes full), the debris collection chamber can be moved relative to the housing (e.g. removed from the housing) to allow easy emptying of the debris from the debris collection chamber. It can thus be appreciated that the disclosed filter unit provides improved, filtering capability, prolonged filtering between emptying of the collection chamber, reduced number of seals and facilitates removal of collected debris from the filter unit .

[0034] Optional features of the second aspect will now be set out. These are applicable singly or in any combination.

[0035] In some embodiments of the second aspect, the debris collection chamber may be removable from the housing in the emptying configuration.

[0036] The debris collection chamber may be one or more of pivotable, slidable or liftable relative to the housing. The debris collection chamber may be contained within or defined by a lid e.g. a removeable lid, the lid being one or more of pivotable, slidable or liftable relative to the housing.

[0037] In some embodiments of the second aspect, the transfer rotation speed may be different e.g. greater than the filtering rotation speed.

[0038] In a third aspect, there is provided a filter unit for filtering debris from debris-laden fluid / liquid, the filter unit comprising: a housing at least partly defining a filtering cavity, the housing comprising a perforated wall portion for accumulation of debris, at least one wiper mounted within the filtering cavity for wiping the perforated wall portion, a debris collection chamber in communication with the filtering cavity via a debris port, wherein the filter unit has a filtering configuration in which the at least one wiper is rotatable at a filtering rotation speed; wherein the filter unit has a transfer configuration in which the at least one wiper is rotatable at a transfer rotation speed for transferring accumulated debris from the filtering cavity to the debris collection chamber; and wherein transfer rotation speed is greater than the filtering rotation speed.

[0039] The inventors have found that by providing at least one wiper that is rotatable at a filtering speed for wiping the perforated wall portion, debris accumulated on the particle collection wall as debris-laden fluid / liquid (e.g. waste (washing) water or drying air) flows through the filter unit can be agglomerated by the shearing action of the wiper against the perforated wall portion. The agglomerated debris tends to remain suspended within the fluid / liquid in the filtering cavity rather than blocking the perforated wall portion and thus the filtering capability of the perforated wall portion is prolonged. After filtering is complete (e.g. at the end of a wash or rinse cycle of a washing appliance, the end of a drying cycle or the end of waste water filtering), the wiper can be rotated at the faster transfer rotation speed to transfer the accumulated debris into the debris collection chamber. This removal of debris from the filtering cavity (by the wiper blade) can be achieved without having to open the filtering cavity (thus reducing the number of seals required in the filtering unit) and without requiring any user input. This creates a better user experience.

[0040] In some embodiments of the second or third aspects, the at least one wiper is rotatable in a first (e.g. filtering) rotation direction and in a second (e.g. transfer) rotation direction. The second rotation direction may be different to the first rotation direction.

[0041] In some embodiments of the second or third aspects, the at least one wiper may comprise a compliant wiping portion for wiping the perforated wall portion.

[0042] In some embodiments of the second or third aspects, the at least one wiper is rotatable in a filtering rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion in the filtering configuration. The at least one wiper may be rotatable in an opposing transfer rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion in the transfer configuration. The first contact surface of the wiping portion may have a different (e.g. smaller) area than the second contact surface of the wiping portion.

[0043] In a fourth aspect, there is provided a filter unit for filtering debris from debris-laden fluid / liquid, the filter unit comprising: a housing at least partly defining a filtering cavity, the housing comprising a perforated wall portion for accumulation of debris, at least one wiper mounted within the filtering cavity and having a compliant wiping portion for wiping the perforated wall portion, wherein the at least one wiper is rotatable in a first rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion; wherein the at least one wiper is rotatable in an opposing second rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion; and wherein the first contact surface of the wiping portion has a different area than the second contact surface of the wiping portion.

[0044] By providing a compliant wiping portion that can flex in opposing directions to provide contact surfaces of differing areas, it is possible to vary the amount of shear provided by the wiping portion against the perforated wall portion. In this way the wiping portion can be optimised for both filtration performance and for the transfer of the accumulated debris to the collection chamber.

[0045] In some embodiments, the first contact surface area is smaller than the second contact surface area.

[0046] In some embodiments of the fourth aspect, the first rotation direction is a filtering rotation direction effected in a filtering configuration of the filter unit in which the wiping portion is flexed in the first flex direction during filtering of the debris-laden fluid / liquid.

[0047] In some embodiments of the fourth aspect, the filter unit further comprises a debris collection chamber in communication with the filtering cavity via a debris port and the filter unit has a transfer configuration in which the at least one wiper is rotatable for transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris port. The second rotation direction may be a transfer rotation direction effected in the transfer configuration of the filter unit in which the wiping portion is flexed in the second flex direction during transfer of the accumulated debris.

[0048] In some embodiments of the fourth aspect, the at least one wiper is rotatable at a first rotation speed in the first rotation direction and at a second rotation speed in the second rotation direction. The second rotation speed may be greater than the first rotation speed.

[0049] In some embodiments of the fourth aspect, the first rotation direction is the filtering rotation direction and the first rotation speed is a filtering rotation speed effected in the filtering configuration of the filter unit. The second rotation direction may be the transfer rotation direction and the second rotation speed may be a transfer rotation speed effected in the transfer configuration of the filter unit. The transfer rotation speed may be greater than the filtering rotation speed.

[0050] In some embodiments of the second to fourth aspects, the perforated wall portion forms the base of the filtering cavity for accumulation of debris in the filtering configuration. Where the filter unit is for use in filtering debris-laden liquid, the filter unit may be airtight above the perforated wall portion so as to form an air pocket in at least the filtering configuration. The debris port / debris collection chamber may be provided in the air pocket formed in the filtering configuration.

[0051] At least the opening to the debris port (from the filtering cavity) may be above the perforated wall portion. The entire debris port may be above the perforated wall portion. The debris collection chamber may be above (i.e. spaced vertically higher than) the perforated wall portion at least in the filtering configuration. The debris collection chamber is preferably at least partly above the debris port.

[0052] In some embodiments of the third or fourth aspects, the debris collection chamber may be movable relative to (e.g. removable from) the housing in the emptying configuration. The debris collection chamber may be one or more of pivotable, slidable or liftable relative to the housing. The debris collection chamber may be contained within or defined by a lid e.g. a removeable lid, the lid being one or more of pivotable, slidable or liftable relative to the housing.

[0053] Further optional features will now be set out. These are applicable singly or in any combination with any of the first to fourth aspects described above.

[0054] The housing (including the perforated wall portion) is preferably a static housing i.e. it does not move / rotate in the filtering configuration or the transfer configuration. For example, the housing / perforated wall portion does not move / rotate relative to a washing / drying / filtering appliance in which it is installed in the filtering configuration or the transfer configuration.

[0055] The housing may comprise a front wall and an axially opposed rear wall, the front and / or rear wall at least partly defining the axial ends of the filtering cavity.

[0056] In preferred embodiments, the at least one wiper is mounted on a rotor shaft extending axially through the filtering cavity e.g. between the front and rear walls. The rotor shaft may extend through the axial centre of the filtering cavity or may be offset from the axial centre towards the perforated wall portion. The rotor shaft (and at least one wiper) may be removeable from the filtering cavity for cleaning i.e. in the emptying configuration of the filter unit.

[0057] The perforated wall portion may extend axially between the front and rear walls. The perforated wall portion preferably defines an arc in a cross-section transverse to the axial extension of the filtering cavity / rotor shaft e.g. an arc centred on the axial centre of the filtering cavity or an arc centred on the rotor shaft. In this way, the at least one wiper can effectively sweep over the perforated wall portion at the filtering rotation speed in order to agglomerate the accumulated debris.

[0058] The arc of the perforated wall portion may subtend an angle of at least 45 degrees such as at least 90 degrees or at least 135 degrees such as between 135 and 250 degrees e.g. between 180 and 230 degrees. This maximises the surface area of the perforated wall portion and thus the filtering capacity of the filter unit.

[0059] The perforated wall portion preferably provides the base of the filtering cavity i.e. the lowermost portion of the filtering cavity when in use (e.g. at least in the filtering configuration). There may be an upper wall portion defining an upper portion of the filtering cavity. The upper wall will be provided in the air pocket in the filtering configuration where the filter unit is airtight above the perforated wall portion. The upper wall portion is uppermost during use (e.g. at least in the filtering configuration). The upper wall portion may extend from or proximal the perforated wall portion. It may be integrally formed with the perforated wall portion. It may extend axially between the front and rear walls. The upper wall portion may be part of the housing or may form part of a movable / removable lid (e.g. part of a lid which may be one or more of pivotable, slidable or liftable relative to the housing) as discussed below. The upper wall portion may also define a portion of the debris collection chamber, e.g. a base of the debris collection chamber.

[0060] In some embodiments, the upper wall portion may also define an arc in a cross-section transverse to the axis of the filtering chamber / rotor shaft e.g. an arc centred on the axial centre of the filtering cavity. The arc of the upper wall portion may subtend an angle of at least 45 degrees such as at least 90 degrees or at least 135 degrees such as around 180 degrees.

[0061] In these embodiments, the perforated wall portion and the upper wall portion together define a filtering cavity which may have a substantially circular cross-section transverse to the axis of the filtering chamber i.e. in a direction between the front and rear walls i.e. they define a filtering cavity that is a substantially cylindrical cavity.

[0062] The filtering cavity may comprise an air bleed. It may be provided above the perforated wall portion. This allows air to bleed into the filtering cavity to allow draining of the liquid from the filtering cavity e.g. in the transfer configuration or in a draining and dewatering configuration of the filter unit as described below. The air bleed may be provided in the upper wall portion or it may be provided in the front / rear wall. The air bleed is provided with a one-way valve (e.g. a flap valve or a float valve) so that air cannot escape from the filtering cavity through the air bleed. In this way, in the filtering configuration, the filter unit is airtight above the perforated wall portion as described for the first aspect. It will be appreciated that, in the filtering configuration, this will result in the formation of an air pocket above the liquid in the filtering cavity. The liquid level will not rise much above the upper edge of the perforated wall portion (e.g. where it meets the upper wall portion) because the air above is trapped within the filter unit.

[0063] The first / filtering rotation speed may be up to and including 60 rpm or 50 rpm, such as 40 or 30 rpm, for example 20 or 10 rpm or 5 rpm e.g. up to and including 4 rpm or 3 rpm, such as up to and including 2 rpm e.g. around 1 rpm. At these low speeds, the shearing action of the at least one wiper tends to roll up and agglomerate any loose, fibrous debris accumulated on the perforated wall portion (as the fluid / liquid filters through the perforated wall portion) into cylindrical “threads” which remain in suspension in the fluid / liquid in the filtering cavity.

[0064] The rotor shaft may be operatively coupled or operatively couplable to a drive unit for driving the shaft and at least one wiper at the first rotation speed e.g. at the filtering rotation speed in the filtering configuration. The drive unit may comprise a motor. The drive unit may comprise a gear box. The drive unit (e.g. the motor / gear box) may be provided in a washing and / or drying appliance body as discussed below for the fifth aspect.

[0065] The rotor shaft may comprise a rotor lock to lock the rotor shaft in a predetermined position. Additionally, alternatively, the drive unit be configured to lock the rotor shaft in a predetermined position. The rotor shaft may be locked in a filling configuration prior to filtering. The predetermined position may be selected such that the debris port is interposed between a first pair of wipers e.g. between two adjacent wipers. Preferably, the liquid inlet is interposed between a second pair of wipers in the predetermined position (although one of the wipers may be common between the first and second pair of wipers). In this way, the first pair of wipers can form a seal e.g. with the upper wall and / or housing to prevent liquid from splashing into the collection chamber via the debris port during filling of the filtering cavity prior to filtering.

[0066] As the debris does not accumulate and block the perforated wall portion, smaller mesh / pore / perforation sizes can be used in the perforated wall portion than are typical for the known mesh filters. For example, a pore size of 60 or 50 microns or less e.g. 40 microns or less, for example 30 microns or less such as around 27 or 25 microns or less can be used.

[0067] The filter unit may comprise a controller for controlling the drive unit. The controller may be configured to control the drive unit to vary the rotation speed e.g. between the first / filtering rotation speed and the second / transfer rotation speed. In some embodiments, the controller may control the drive unit to vary the first / filtering rotation speed in the filtering configuration. The controller may be configured to control the drive unit to lock the rotor shaft in the predetermined position prior to filtering. The controller may be provided in a washing and / or drying appliance such as that described on the fifth aspect below.

[0068] The filter unit may comprise a sensor operatively coupled to the controller. The sensor may comprise a pressure sensor for measuring back pressure within the filtering cavity. The sensor may additionally or alternatively comprise a liquid level sensor for measuring liquid level within the filtering cavity.

[0069] Where the debris-laden fluid / liquid comprises a particularly high level of debris, it may be desirable to increase the filtering rotation speed to ensure effective wiping of the perforated wall portion and thus maintain the flow rate through the filter unit. The controller may be configured to maintain a constant flow rate of fluid / liquid through the perforated wall portion in the filtering configuration e.g. by varying the filtering rotation speed. For example, an increase in pressure and / or an increase in water level detected by the sensor(s) may indicate partial blocking of the perforated wall portion and the sensor can generate a signal causing the controller to trigger an increase in the filtering rotation speed (e.g. from 1 or 2 rpm to 3 or 4 rpm) to increase wiping of the perforated wall portion by the at least one wiper.

[0070] Conversely, where the debris-laden fluid / liquid comprises a particularly low level of debris, it may be desirable to reduce the filtering rotation speed or cease rotation of the at least one wiper. A decrease in pressure and / or a decrease in water level detected by the sensor(s) may cause the sensor to generate a signal causing the controller to trigger decrease the filtering rotation speed (e.g. from 1 or 2 rpm to 0.5 to 1 rpm) or it may trigger a pause / cessation of rotation.

[0071] The controller may also be configured to allow pulsing of the rotation of the at least one wiper in the filtering configuration. The length of pause and / or frequency of the pulsing will affect the flow rate through the perforated wall portion - short pauses and high frequency pulsing will increase the flow rate. The controller may also be configured to vary the frequency of pulsing. By varying the first / filtering rotation speed and / or pausing the filtering rotation and / or pulsing the filtering rotation, the controller may be configured to maintain a constant flow rate through the perforated wall portion.

[0072] The at least one wiper may have an attached end attached to the rotor shaft. The attached end may be an axially-extending edge attached along at least a portion of the axial length of the rotor shaft. The edge may be attached linearly (axially) or helically, for example.

[0073] The at least one wiper may extend radially or tangentially from its attached end / edge (at the shaft) to a radially-outer wiping portion having a wiping end / edge distal the rotor shaft.

[0074] At least the wiping portion of the at least one wiper may be compliant i.e. formed of deformable e.g. soft, flexible material such as rubber. In order to prolong the life of the compliant wiping portion (or compliant wiper), it may be coated, wrapped or faced with a harder material such as nylon.

[0075] The distance from the attached end / edge to the wiping end / edge of the undeformed wiper may be greater than the distance from the rotor shaft to the perforated wall portion such that the wiping portion is deflected (by contact with the perforated wall portion) proximal the perforated wall portion. This deflection provides a greater contact area between the wiping portion of the wiper and perforated wall portion to increase the shear force. The wiping portion may be sufficiently deflected (as a result of the radial length between the attached end / edge and the wiping end / edge being sufficiently greater than the radial length between the shaft and the perforated wall portion) that the wiping portion comprises a circumferentially- extending wiping portion.

[0076] In some embodiments, the entire wiper may be compliant. This may be the case where the rotor shaft is off-set from the axial centre of the filtering cavity (i.e. off-set towards the perforated wall portion). In this way, where there is a plurality of wipers (as discussed below), the wipers and rotor shaft can function as a flexible vane impeller pump acting to force fluid / liq uid throught the perforated wall portion.

[0077] In other embodiments, only the wiping portion is compliant and is mounted on a rigid portion extending from the attached end / edge to the wiping portion. The rigid portion may be axially-extending or helically extending along the rotor shaft. In these embodiments, the rigid portion may comprise a seat for affixing the wiping portion. The seat may be asymmetrical so that asymmetrical flexing of the wiping portion can be effected as described for the fourth aspect i.e. so that flexing of the wiping portion when the at least one wiper is rotated in one direction differs from that when the at least one wiper is rotated in the opposite direction as described above for the fourth aspect.

[0078] For example, the (compliant) wiping portion may be interposed between seat extensions of differing lengths (i.e. differing radial extensions). In this way, the degree of flexing of the wiping portion against the perforated wall portion can be varied depending on the rotation direction. For example, reduced flexing can be achieved in the first (e.g. filtering) rotation direction with the longer seat extension leading and the wiping portion flexed against the shorter seat extension creating a first contact surface having a reduced surface area. This may be desirable in the filtering configuration (at least where the debris is fibrous) as it creates a reduced force / lower shear on the accumulated debris and thus is more likely to lead to agglomeration of the debris rather than forcing it into the perforations of the perforated wall portion. Increased flexing (and increased contact surface area) can be achieved in the second (transfer) rotation direction with the shorter seat extension leading and the wiping portion flexed against the longer seat extension. This increases the stiffness of the wiping portion. This may be desirable in the transfer configuration (at least for fibrous debris) as it may increase tangential force on the agglomerated debris.

[0079] In some embodiments, the wiping portion e.g. the wiping portion mounted on the rigid portion is an axially- or helically-extending blade i.e. a compliant axially- or helically-extending blade. In other embodiments, the wiping portion e.g. the wiping portion mounted on the rigid arm comprises an axially-or helically-extending row of compliant bristles.

[0080] The entirety of the at least one wiper may be an axially- or helically-extending blade where the wiper is integrally formed from its attached edge to its wiping edge.

[0081] The entirety of the at least one wiper may comprise an axially- or helically-extending row of compliant bristles, each bristle extending between its respective attached and wiping ends.

[0082] There may be a plurality of wipers mounted on the rotor shaft. There may be, for example, two, three, four, five, six or more wipers. The wipers (e.g. blades or rows of bristles) may be equally-spaced around the circumference of the rotor shaft.

[0083] The filter unit comprises a fluid / liquid inlet into the filtering cavity for inlet of debris-laden fluid / liquid in the filtering configuration. The fluid / liquid inlet may be provided in the front or rear wall of the housing. The fluid / liquid inlet may be an aperture in the housing e.g. in the front or rear wall. There may be a fluid / liquid inlet conduit in fluid communication with the fluid / liquid inlet aperture.

[0084] A fluid / liquid feed containing debris-laden fluid / liquid may be connectable to the fluid / liquid inlet or the fluid / liquid inlet conduit. The fluid / liquid may enter the filtering chamber axially (i.e. the inlet aperture and at least a portion of any fluid / liquid inlet conduit may have an axis parallel to the axis of the filtering cavity / rotor shaft). The fluid / liquid inlet conduit may be fed by the fluid / liquid feed under gravity or may be in fluid communication with a pump for feeding debris-laden fluid / liquid into the filtering cavity under gravity or under the pump pressure respectively. The fluid / liquid inlet may be provided in the front / rear wall e.g. at a position below the rotor shaft e.g. vertically spaced below e.g. vertically aligned with the rotor shaft. In other embodiments, the fluid / liquid inlet (for debris-laden fluid / liquid) is provided e.g. in the front / rear wall above the rotor shaft.

[0085] A one-way fluid / liquid inlet valve (e.g. a simple flap valve or a solenoid-controlled valve) may be provided to ensure fluid / liquid can only flow into and not out of the filtering cavity through the fluid / liquid inlet. The fluid / liquid inlet valve is open / openable in the filtering configuration. It is closed in the draining, dewatering and transfer configurations. The liquid inlet valve prevents liquid flowing back from the filtering cavity to the pump. It can also be used to pause the liquid inlet flow e.g. liquid inlet flow under gravity to meter the liquid inlet flow into the filtering cavity.

[0086] The fluid / liquid inlet valve may be integrated with the air bleed valve e.g. by using a two-way integrated valve with one port for air bleed and one port for fluid / liquid ingress, the two ports being opened alternatively. The fluid / liquid port will be open / openable in the filtering configuration and the air bleed port will be open / openable in the transfer / dewatering configuration

[0087] The fluid / liquid inlet valve may also be configured to prevent inlet of fluid / liquid into the filtering cavity when the collection chamber is removed from the filtering cavity i.e. in the emptying configuration of the filter unit.

[0088] The perforated wall portion provides the base of the filtering cavity such that filtered liquid can drain under gravity (and / or filtered fluid / liquid can exit under pump pressure) from the filtering cavity in the filtering configuration. The filter unit may further comprise an outer tank at least partially enclosing the housing. For example, the outer tank may be in fluid communication with the perforated wall portion to collect and / or channel the filtered liquid e.g. to channel it to waste and / or to vent filtered air. The tank may be provided as part of the washing / drying appliance of the fifth aspect described below.

[0089] In some embodiments, the axial centre of the filtering cavity and the axial centre of the debris collection chamber are vertically aligned in a cross-section transverse to the axis of the filtering cavity / rotor shaft. The fluid / liquid inlet (in the front or rear wall) may also be vertically aligned with the axial centre of the filtering cavity and the axial centre of the collection chamber in a cross-section transverse to the axis of the filtering cavity / rotor shaft.

[0090] The debris port is in fluid communication with both the filtering cavity and the collection chamber. The opening to the debris port from the filtering cavity may be provided in the upper wall portion of the filtering cavity. The debris port may extend to an exit at the debris collection chamber. Any one or more of the opening to debris port, the debris port, and the exit of the debris port may extend axially e.g. axially between the front and rear walls of the housing i.e. the debris port may be a slotted port with a slotted opening at the filtering cavity and slotted exit at the debris collection chamber. The debris port may extend from the opening in the filtering cavity to the exit at the debris collection chamber in a direction extending tangentially from a circle swept by the wiping portion of the at least one wiper to the debris collection chamber e.g. to the vertically uppermost point of the debris collection chamber.

[0091] Where the debris collection chamber is above the filtering cavity, the debris port may extend from the filtering cavity to the debris collection chamber in a direction extending at an angle greater than zero and 90 degrees or less from vertical (in a cross-section transverse to the filtering cavity / rotor shaft), preferably at an angle between 10 and 80 degrees such as between 20 and 70 degrees or 20 and 60 degrees, for example between 25 and 50 degrees or 30 and 50 degrees e.g. between 40 and 45 degrees such as around 40 degrees.

[0092] The drive unit (e.g. motor / gear box) may be configured for driving the shaft and at least one wiper at the transfer rotation speed in the transfer configuration. The transfer rotation may be in the same or opposite direction to the filtering rotation. The transfer rotation speed is preferably faster than the filtering rotation speed. The transfer rotation speed may be greater than 60 rpm, e.g. greater than 100 rpm or 250 rpm, such as greater than 300, 400, 500, 600 ,700 or 800 rpm e.g. around 850 rpm. At these higher speeds and in the absence of liquid in the filtering cavity, the at least one wiper blade can impart sufficient tangential momentum to the agglomerated debris to ‘fling’ it (e.g. against gravity) and into the collection chamber in the transfer configuration.

[0093] The filter unit may further comprise a de-watering configuration in which the at least one wiper is further rotatable at a de-watering rotation speed for de-watering agglomerated debris after liquid filtering (and draining) and prior to transfer into the debris collection chamber. The drive unit may be configured for driving the shaft and at least one blade at the de-watering rotation speed. The de-watering rotation may be in the same or opposite direction to the filtering rotation. The dewatering rotation speed is preferably faster than the filtering rotation speed. It is preferably slower than the transfer rotation speed. The dewatering rotation speed may be greater than 5 rpm, e.g. between 20-100 rpm, such as between 30 and 80 or 40 and 70 rpm, such as between 50 and 60 rpm.

[0094] The debris collection chamber may have an elongate axis extending parallel to the rotor shaft between opposing axial ends. One of the axial ends (e.g. the rear axial end proximal the rear wall of the housing) may be open). The debris collection chamber may have an elongate opening i.e. a slot in communication with the exit of the debris port.

[0095] The debris collection chamber may have a guiding wall for guiding the path of the debris into the debris collection chamber. The guiding wall may define an arc e.g. at least a substantially semi-circular arc. The debris impacts against the guiding wall which will slow and deflect the debris from its path tangential to the path of the wiping portion of the at least one wiper along the arc so that it then falls into the base of the debris collection chamber under gravity.

[0096] In some embodiments, the debris collection chamber may have a retaining wall for retaining debris in the collection chamber. It may extend adjacent and co-linear with an inner wall of the debris port. In other embodiments, it may define an inner wall of the debris port. A free edge of the retaining wall distal the filtering cavity may define the inner edge of the elongate opening of the collection chamber. The retaining wall may have an outer surface which directs the debris along its path (tangential to the path of the wiping portion of the least one wiper) and into the opening of the collection chamber. The base of the collection chamber may be partly defined by an inner surface of the retaining wall.

[0097] The collection chamber may comprise a drain e.g. at its base to ensure that any residual water in the collected debris can drain back from the debris collection chamber e.g. back into the filtering cavity where the debris collection chamber is vertically spaced above the filtering cavity.

[0098] The debris collection chamber may comprise a scraper or auger e.g. an axial or radial scraper / auger for ejection of the collected debris from the debris collection chamber after its removal from the housing i.e. in the emptying configuration of the filter unit. The debris collection chamber may have an open axial end (e.g. a rear open axial end proximal the rear wall of the housing) to facilitate expulsion of the collected debris e.g. using the axial scraper / auger. Any radial scraper / auger may be configured to expel collected debris via the elongate opening of the debris collection chamber. The radial scraper may have a scaping edge that scrapes the guide wall of the debris collection chamber.

[0099] The debris collection chamber may comprise a locking element for releasably locking it within the housing.

[0100] The debris collection chamber may be slidable relative to the housing e.g. axially slidable in a direction parallel to the axis of the filtering cavity / rotor shaft. For example, the debris collection chamber may be removed from the housing by axial sliding. The debris collection chamber may be axially slidable through an aperture in the front or rear wall of the housing. In these embodiments, the debris collection chamber forms an airtight seal with the housing e.g. with the front or rear wall of the housing. For example, the collection chamber may comprise an axial end (e.g. a front axial end wall proximal the front wall of the housing) which forms a seal with the housing (e.g. the front wall of the housing) e.g. via an o-ring. For example, the axial end of the collection chamber may be external to the housing and may form a sealing connection with an outer surface of the front / rear wall around the aperture.

[0101] The aperture may comprise a notch for allowing passage of the locking element of the collection chamber. The collection chamber may be rotatable within the housing so that the locking element is aligned with the notch (e.g. in keyed arrangement) to allow axial sliding of the collection chamber relative to the housing. In order to lock the collection chamber within the housing, the collection chamber may be rotatable to that the locking element is mis-aligned with the notch in the aperture so that axial sliding is prevented by abutment of the locking element against the front / rear wall. In other words, the debris locking element of the debris collection chamber and notch in the aperture of the housing may form a bayonet fitting.

[0102] The axial end (e.g. front axial end) of the collection chamber may further comprise a gripping portion e.g. a projection or handle for gripping the collection chamber for removal from the housing. The opposing (e.g. rear axial end) of the collection chamber may be open to allow ejection of collected debris after removal of the debris collection chamber from the housing in the emptying configuration.

[0103] In some embodiments, the filtering cavity may be fully defined and fully enclosed by the housing. For example, the housing may comprise the upper wall portion extending from the perforated wall portion. The debris port may be defined by the housing.

[0104] The debris collection chamber may be slidable relative to the housing e.g. slidable from the housing.

[0105] The housing may further comprise a pocket portion defining a pocket (or cavity) for receiving the removable collection chamber. The pocket (portion) may be airtight in the filtering configuration.

[0106] The pocket portion (and pocket) may be axially extending between the front and rear walls. The aperture in the front / rear wall through which the collection chamber is slidable may be in communication with the pocket, the collection chamber being axially slidable from the pocket (and thus from the housing) through the aperture in the emptying configuration.

[0107] The pocket is distal the perforated wall portion. The pocket is preferably spaced vertically above the rotor shaft and preferably above the filtering cavity i.e. the filtering cavity is interposed between the perforated wall portion and the pocket. In some embodiments, the axial centre of the filtering cavity and the axial centre of the pocket are vertically aligned in a cross-section transverse to the axis of the rotor shaft. The fluid / liquid inlet may also be vertically aligned with the axial centre of the filtering cavity and the axial centre of the pocket in a cross-section transverse to the axis of the rotor shaft.

[0108] In other embodiments, the collection chamber is movable relative to (e.g. removable from) the housing in a direction that is not co-linear with the axis of the filtering cavity / rotor shaft (e.g. perpendicular to the axis of the filtering cavity / rotor shaft) e.g. by lifting the collection chamber away from the filtering cavity.

[0109] The filter unit may further comprise a lid. In these embodiments, the collection chamber is mounted within or defined by the lid. In some of these embodiments, the lid (rather than the housing) may define the upper wall portion of the filtering cavity. The lid may also define the debris port. The lid will preferably be airtight in the filtering configuration i.e. the lid preferably forms an airtight seal with the housing. The lid may be at least partly formed of a transparent material to enable the user to see when the debris collection chamber needs emptying.

[0110] The lid may be one or more of pivotable, slidable or liftable relative to the housing.

[0111] For example, the lid may be liftable from the housing (i.e. completely detachable from the housing) in a direction that is not co-linear with the axis of the filtering cavity (e.g. perpendicular to the axis of the filtering cavity).

[0112] In some embodiments, the housing may further comprise side walls extending from opposing edges of the perforated wall portion (perpendicular to the front / rear walls). The side walls may extend vertically and / or horizontally. The lid may comprise at least one sealing wall (e.g. opposing sealing walls where the lid lifts away from the housing) which seal again these housing side walls e.g. against inner surfaces of the vertical side walls and / or against the horizontal side walls. The lid will also seal against the front / rear walls, e.g. against uppermost edges of the front / rear walls.

[0113] In other embodiments, the lid may be pivotable and / or slidable relative to the housing e.g. the lid may be pivotably connected to the housing e.g. along an axially-extending edge so that the lid can pivot about the axially-extending edge to open the filtering cavity. As the lid pivots, the collection chamber (which may be defined by the pivotable lid) moves away from the filtering cavity. The lid may be both pivotable and slidable relative to the housing. For example, after pivoting of the lid to open the filtering cavity, the lid may be slid relative to the housing to remove it from the housing to facilitate emptying of the collection chamber in the emptying configuration. After emptying, the lid may be slid back into position to reinstate its pivotal connection to the housing and then pivoted back to close the filtering cavity.

[0114] The pivotable lid may seal against a flange e.g. an axially-extending flange extending from the housing above the perforated wall portion in the filtering configuration.

[0115] In embodiments where the lid is movable (e.g. one or more of pivotable, slidable and liftable) relative to the housing (e.g. removable from the housing), the debris collection chamber may comprise a radial scraper for ejecting collected debris from the elongate opening of the debris collection chamber.

[0116] In yet further embodiments, the filter unit comprises a sealing portion between the collection chamber and the debris port and the collection chamber is separable from the housing (e.g. by lifting in a direction not co-linear with the axis of the filtering cavity / rotor shaft, for example, perpendicular to the axis of the filtering cavity / rotor shaft) at the sealing portion. The debris port and collection chamber preferably form an airtight seal at the sealing portion.

[0117] The sealing portion may comprise a sealing collar provided on the debris port or on the collection chamber, the sealing collar surrounding the join between the debris port and chamber. In these embodiments, the upper wall portion of the filtering cavity is defined by the housing (and may be integral with the perforated wall portion). It may define an arc as described above such that the filtering cavity is a substantially cylindrical filtering cavity.

[0118] Any of the filter units described herein may be dimensioned so as to fit within a space defined by a detergent dosing drawer of a washing appliance. For example, the axial extension of the filtering cavity may be around 300mm. The width of the filtering cavity (in a direction perpendicular to the axial extension) may be around 200mm. In this way, the filter unit can be fitted to a washing appliance by a manufacturer in place of the dosing drawer with minimal structural modifications to the washing appliance.

[0119] In a fifth aspect, there is provided a washing and / or drying appliance comprising a filter unit according to any one of the first to fourth aspects.

[0120] The washing and / or drying appliance may comprise the drive unit (e.g. the motor / gear box) of the filter unit. The drive unit may comprise a connector spindle for releasable operative coupling to the rotor shaft.

[0121] The washing appliance may comprise a liquid feed for releasable connection to the liquid inlet of the filter unit for delivery of debris-laden liquid into the filtering cavity. The liquid feed will be connected via a pump to the washing drum of the washing appliance for transfer of debris-laden liquid from the washing drum to the filtering cavity.

[0122] The washing appliance may comprise a drain feed. The drain feed may be in fluid communication with waste or with the washing drum. Filtered liquid leaving the filter unit via the perforated wall portion may drain to waste or back to the washing drum.

[0123] The drying appliance may comprise an air feed for releasable connection to the fluid inlet of the filter unit for delivery of debris-laden air into the filtering cavity. The air feed will be connected via a pump to the drying drum of the drying appliance for transfer of debris-laden air from the drying drum to the filtering cavity.

[0124] The filter unit may be slidably fitted into the body of the washing and / or drying appliance. It may be slidably fitted into a filter compartment which may define the tank referred to above. The drain feed may be provided in e.g. at the base of the filter compartment / tank. The filter compartment / tank may comprise a door. The door may have a handle or recess for sliding the filter unit from the filter compartment / tank in the emptying configuration.

[0125] The filter compartment / tank may be adjacent to a dosing compartment containing one or more dosing drawers for containing detergent and / or fabric softener. The housing may be connected to or integrally formed with at least one dosing drawer provided in the dosing compartment. In other embodiments, the filter compartment / tank may be below the washing drum of the washing appliance so that the liquid inlet is fed from the washing drum under gravity.

[0126] The rotor shaft may be sprung-loaded within the filter unit to allow removal of the rotor shaft and at least one wiper from the filtering cavity in the emptying configuration.

[0127] In a sixth aspect, there is provided a method of using the filter unit according to the first aspect for filtering debris from a debris-laden liquid, the method comprising: supplying debris-laden liquid into the filtering cavity to accumulate debris on the perforated wall portion in the filtering configuration, draining the filtering cavity; and transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris port, wherein the filter unit is airtight above the perforated wall portion in at least the filtering configuration and wherein at least an opening from the filtering cavity into the debris port is above the perforated wall portion.

[0128] Optional features of the sixth aspect will now be set out. These are applicable singly or in any combination.

[0129] In some embodiments of the sixth aspect where the filter unit further comprises at least one wiper mounted within the filtering cavity, the method comprises rotating the at least one wiper at the filtering rotation speed to agglomerate debris collected on the perforated wall portion in a filtration configuration.

[0130] In some of these embodiments, the method further comprises rotating the at least one wiper at the transfer rotation speed for transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris exit port in a transfer configuration.

[0131] The transfer rotation speed may be greater than the filtering rotation speed.

[0132] In some embodiments of the sixth aspect, the method may comprise rotating the wiper in a first (e.g. filtering) rotation direction and in a second (e.g. transfer) rotation direction. The second rotation direction may be different to the first rotation direction.

[0133] In some embodiments of the sixth aspect, where the at least one wiper comprises a compliant wiping portion for wiping the perforated wall portion, the method may comprise rotating the at least one wiper in the first rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion. The method may further comprise rotating the at least one wiper in an opposing second rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion. The first contact surface of the wiping portion may have a different area than the second contact surface of the wiping portion.

[0134] In some embodiments of the sixth aspect, the first rotation direction is a filtering rotation direction and is effected in the filtering configuration with the wiping portion flexed in the first flex direction during filtering.

[0135] In some embodiments of the sixth aspect, the second rotation direction is a transfer rotation direction effected in the transfer configuration with the wiping portion flexed in the opposing second flex direction for transferring accumulated debris from the filtering cavity to the debris collection chamber.

[0136] In some embodiments, the first contact surface area is less than the second contact surface area.

[0137] In some embodiments of the sixth aspect, the method comprises moving (e.g. one or more of pivoting, sliding or lifting) the debris collection chamber relative to the housing (e.g. removing it from the housing) in an emptying configuration.

[0138] In a seventh aspect, there is provided a method of using the filter unit according to the second aspect for filtering debris from a debris-laden fluid / liquid, the method comprising: supplying debris-laden fluid / liquid into the filtering cavity rotating the at least one wiper at the filtering rotation speed to agglomerate debris collected on the perforated wall portion, optionally draining the filtering cavity; rotating the at least one wiper at the transfer rotation speed for transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris exit port; and moving the debris collection chamber relative to the housing for emptying the debris collection chamber.

[0139] Optional features of the seventh aspect will now be set out. These are applicable singly or in any combination.

[0140] In some embodiments of the seventh aspect, the method comprises one or more of pivoting, sliding or lifting the debris collection chamber relative to the housing e.g. removing it from the housing in the emptying configuration.

[0141] Ideally the supplying, debris agglomeration (filtering), draining and debris transferring steps are effected multiple times prior to the moving step i.e. the emptying of the debris collection chamber does not need to occur after each use of the filter unit.

[0142] In some embodiments of the seventh aspect, the transfer rotation speed may be different e.g. greater than the filtering rotation speed. In an eighth aspect, there is provided a method of using the filter unit according to the third aspect for filtering debris from a debris-laden fluid / liquid, the method comprising: supplying debris-laden fluid / liquid into the filtering cavity rotating the at least one wiper at the filtering rotation speed to agglomerate debris collected on the perforated wall portion, optionally draining the filtering cavity; and rotating the at least one wiper at the transfer rotation speed for transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris exit port; wherein transfer rotation speed is greater than the filtering rotation speed.

[0143] In some embodiments of the seventh or eighth aspects, the method comprises rotating the at least one wiper in a first (e.g. filtering) rotation direction and in a second (e.g. transfer) rotation direction. The second rotation direction may be different to the first rotation direction.

[0144] In some embodiments of the seventh or eighth aspects, where the at least one wiper comprises a compliant wiping portion for wiping the perforated wall portion, the method comprises rotating the at least one wiper in a filtering rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion in the filtering configuration. The method may comprise rotating the at least one wiper in an opposing transfer rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion in the transfer configuration. The first contact surface of the wiping portion may have a different (e.g. smaller) area than the second contact surface of the wiping portion.

[0145] In a ninth aspect, there is provided a method of using the filter unit according to the fourth aspect for filtering debris from a debris-laden fluid / liquid, the method comprising: supplying debris-laden fluid / liquid into the filtering cavity rotating the at least one wiper in a first rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion, optionally draining the filtering cavity; and rotating the at least one wiper in an opposing second rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion, wherein the first contact surface of the wiping portion has a different area than the second contact surface of the wiping portion.

[0146] In some embodiments of the ninth aspect, the first contact surface area is smaller than the second contact surface area. In some embodiments of the ninth aspect, the first rotation direction is a filtering rotation direction effected in a filtering configuration of the filter unit in which the wiping portion is flexed in the first flex direction during filtering of the debris-laden fluid / liquid.

[0147] In some embodiments of the ninth aspect, where the filter unit further comprises a debris collection chamber in communication with the filtering cavity via a debris port, the method comprises rotating the at least one wiper in the transfer configuration for transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris port. The second rotation direction may be a transfer rotation direction effected in the transfer configuration of the filter unit in which the wiping portion is flexed in the second flex direction during transfer of the accumulated debris.

[0148] In some embodiments of the ninth aspect, the method comprises rotating the at least one wiper at a first rotation speed in the first rotation direction and at a second rotation speed in the second rotation direction. The second rotation speed may be greater than the first rotation speed.

[0149] In some embodiments of the ninth aspect, the first rotation direction is the filtering rotation direction and the first rotation speed is a filtering rotation speed effected in the filtering configuration of the filter unit. The second rotation direction may be the transfer rotation direction and the second rotation speed may be a transfer rotation speed effected in the transfer configuration of the filter unit. The transfer rotation speed may be greater than the filtering rotation speed.

[0150] In some embodiments of the seventh to ninth aspects, the filter unit is airtight above the perforated wall portion in at least the filtering configuration and wherein at least an opening from the filtering cavity into the debris port is above the perforated wall portion.

[0151] In some embodiments of the eighth or ninth aspects, the method comprises moving (e.g. one of more of lifting, pivoting or sliding) the debris collection chamber relative to (e.g. removing it from) the housing in the emptying configuration.

[0152] Further optional method features will now be set out. These are applicable singly or in any combination with any of the sixth to ninth aspects described above.

[0153] In some embodiments, the method comprises maintaining the housing in a fixed / static position e.g. within the washing and / or drying appliance whilst rotating the at least one wiper at the filtering rotation speed and whilst rotating the at least one wiper at the transfer rotation speed.

[0154] In some embodiments, the method comprises bleeding air into the filtering cavity to drain the filtering cavity in the draining / dewatering configuration e.g. bleeding air into the filtering cavity through the air bleed. The method may comprise rotating the at least one wiper (e.g. the plurality of wipers) at a filtering rotation speed up to and including 60 rpm or 50 rpm, such as 40 or 30 rpm, for example 20 or 10 rpm or 5 rpm e.g. up to and including 4 rpm or 3 rpm, such as up to and including 2 rpm e.g. around 1 rpm. At these low speeds, the shearing action of the at least one wiper tends to roll up and agglomerate any loose, fibrous debris collected on the perforated wall portion (as the fluid / liquid filters through the perforated wall portion) into threads which remain in suspension in the liquid in the filtering cavity.

[0155] In some embodiments, the method comprises monitoring back pressure within the cavity and / or liquid level within the cavity. The method may comprise adjusting (e.g. increasing) the filtering rotation speed if an increase in back pressure and / or a rise in liquid level is detected. The method may also comprise reducing or stalling the rotor rotation if no increase in back pressure is detected. The method may comprise varying the filtering rotation speed to effect a constant flow rate through the filter unit. The method may comprise pulsing the filtering rotation. It may comprise varying the pulse frequency.

[0156] The method may comprise rotating the at least one wiper (e.g. the plurality of wipers) in the transfer configuration at the transfer rotation speed that is faster than the filtering rotation speed. The method may comprise rotating the at least one wiper (e.g. the plurality of wipers) at a transfer rotation speed greater than 60 rpm, e.g. greater than 100 rpm or 250 rpm, such as greater than 300, 400, 500, 600 ,700 or 800 rpm e.g. around 850 rpm. At these higher speeds and in the absence of liquid in the filtering cavity, the agglomerated debris within the housing can be flung tangentially to the cavity (e.g. upwards against gravity) and into a collection chamber vertically spaced above the filtering cavity.

[0157] The method may comprise transferring the accumulated debris through the debris exit port in a direction extending tangentially from a circle swept by the wiping end of the at least one wiper to the collection chamber e.g. to the vertically uppermost point of the collection chamber.

[0158] The method may comprise transferring the accumulated debris through the debris port in a direction extending at an angle greater than zero and less than 90 degrees from vertical (in a cross-section transverse to the rotor shaft), preferably at an angle between 10 and 80 degrees such as between 20 and 70 degrees or 20 and 60 degrees, for example between 25 and 50 degrees or 30 and 50 degrees e.g. between 43 and 45 degrees such as around 40 degrees.

[0159] The method may further comprise rotating the at least one wiper (e.g. the plurality of wipers) at a dewatering rotation speed for de-watering agglomerated debris after draining of the filtering cavity and prior to transfer into the debris collection chamber. The method may comprise rotating the at least one wiper (e.g. the plurality of wipers) at the de-watering rotation speed in the same or opposite direction to the filtering rotation. The method may comprise rotating the at least one wiper (e.g. the plurality of wipers) at a dewatering rotation speed that is faster than the filtering rotation speed. The method may comprise rotating the at least one wiper (e.g. the plurality of wipers) at a dewatering rotation speed that is lower than the transfer rotation speed. The method may comprise rotating the at least one wiper (e.g. the plurality of wipers) at a dewatering rotation speed that greater than 5 rpm, e.g. between 20-100 rpm, such as between 30 and 80 or 40 and 70 rpm, such as between 50 and 60 rpm.

[0160] The method may comprise removing the collection chamber from the housing by axial sliding in a direction parallel to the axis of the filtering cavity / rotor shaft.

[0161] The method may comprise removing the collection chamber from the housing in a direction not co-linear with the axis of the filtering cavity / rotation shaft (e.g. perpendicular to the axis of the filtering cavity / rotor shaft) e.g. by lifting the collection chamber away from the filtering cavity.

[0162] In some embodiments, the method further comprises removing a removable lid from the housing, the removable lid enclosing or defining the collection chamber. These methods may comprise lifting the lid from the housing in a direction not co-linear with the axis of the filtering cavity / rotation shaft (e.g. perpendicular to the axis of the filtering cavity).

[0163] In some embodiments, the method comprises pivoting a pivotable lid relative to the housing, the pivotable lid enclosing or defining the collection chamber. These methods may comprise pivoting the lid relative to the housing in a direction not co-linear with the axis of the filtering cavity / rotation shaft (e.g. perpendicular to the axis of the filtering cavity). The method may further comprise sliding the lid to remove it from the housing in the emptying configuration.

[0164] In some embodiments, the method comprises removing debris from the collection chamber using a scraper / auger e.g. an axial or radial scraper / auger.

[0165] The disclosure includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0166] Summary of the Figures

[0167] Embodiments will now be discussed with reference to the accompanying figures in which:

[0168] Figure 1A is a schematic cross-sectional drawing of a first embodiment of a filter unit;

[0169] Figure 1 B is a schematic cross-sectional drawing of the first embodiment of the filter unit along a longitudinal axis thereof;

[0170] Figure 2 is a schematic cross-sectional drawing of a second embodiment of a filter unit;

[0171] Figure 3 is a schematic cross-sectional drawing of a third embodiment of a filter unit;

[0172] Figure 4 is a schematic cross-sectional drawing of a filter cavity and a plurality of wipers mounted therein; Figures 5A and 5B show an excerpted detail from the drawing of Figure 4, illustrating details of the wiper’s construction;

[0173] Figure 6 is a schematic cross-sectional drawing of a filter cavity and a plurality of wipers mounted therein;

[0174] Figures 7A and 7B show cross-sections through a further embodiment of the filter unit in situ in a washing appliance; and

[0175] Figure 8 is a flowchart illustrating a method of using a filter unit for filtering debris from a debris-laden liquid.

[0176] Detailed Description

[0177] Aspects and embodiments will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art.

[0178] Figures 1 A and 1 B show schematic cross-sectional drawings of a first embodiment of a filter unit 1 .

[0179] The filter unit 1 is for filtering debris-laden fluid / liquid such that filtered fluid / liquid can be discharged from the filter unit 1 and the debris collected for disposal. Although the following discussion refers to filtering a debris-laden liquid, the discussion is equally applicable to the filtering of debris-laden gas (e.g. air).

[0180] The filter unit 1 comprises a housing 10 defining a filtering cavity 11 that is configured to be charged (in a filtering configuration) with debris-laden liquid via a liquid inlet (not shown) from a liquid feed. The housing 10 comprises a perforated wall portion 13 that partially defines the filtering cavity 11. The perforated wall portion 13 defines an arc subtending an angle of approximately 210 degrees, such that a large filtering area is provided within the filter unit 1 , thereby increasing the filtering capacity of the filter unit 1 .

[0181] The perforated wall portion 13 acts as the filtering surface within the filter unit 1 , with liquid able to pass through the perforations, but the debris contained within the liquid retained. In Figure 1 , the perforated wall portion 13 provides the base of the filtering cavity 11 i.e. the lowermost portion of the filtering cavity 11 when in use. Accordingly, debris-laden liquid entering the cavity 11 via the liquid inlet is filtered through the perforated wall portion 13 under gravity assisted by pump pressure of the liquid feed.

[0182] The cavity 11 is further defined by an upper wall portion 14 that extends from the perforated wall portion 13. The upper wall portion 14 is arcuate having the same axial centre 15 as the perforated wall portion 13, such that the perforated wall portion 13 and the upper wall portion 14 together a substantially cylindrical filtering cavity 11 . The filtering cavity 11 is further defined (at its axial ends) by front and rear walls 16, 17 (see Figure 1 B).

[0183] The liquid inlet may be provided in the rear end wall 17.

[0184] Mounted within the filtering cavity 11 are six wipers 20. The wipers 20 are each mounted to a rotor shaft 19 that extends axially through the filtering cavity 11 (i.e. between the front and rear walls 16, 17 of the cavity 11). The attached edge 21 of each wiper by which it is mounted to the rotor shaft 19 extends axially along the rotor shaft 19 between the front and rear walls 16, 17 of the cavity 11 (as shown in Figure 1 B), such that each wiper 20 is a substantially planar member i.e. a blade. The wipers 20 each extend radially from the rotor shaft 19 towards the periphery of the filtering cavity 11. It can be appreciated that the axis of the rotor shaft 19 is coincident with the axis 15 of the substantially cylindrical cavity 11 (i.e. the centre point of the arc of the perforated wall portion 13 and upper wall portion 14). Each wiper 120 extends from its attached edge 21 towards a radially-outer wiping portion 22 that has a wiping edge 23 distal the rotor shaft 19.

[0185] The six wipers 120 are equiangularly spaced about the rotor shaft 19 (i.e. an angle of 60 degrees is provided between adjacent wipers 20). It can be appreciated that different numbers and / or spacings of the wipers 20 may be used.

[0186] The rotor shaft 19 can be operatively coupled to a drive unit including a motor and gear box (not shown in Figures 1A / 1 B) for driving the rotation of the shaft 19, and in turn the wipers 20, relative to the cavity 11 , which is stationary in the filtering configuration. By rotating the wipers 20, they can wipe over debris accumulating on the perforated wall portion 13 as liquid is filtered therethrough. This repeated wiping motion causes the agglomeration of the debris due to the shear forces the wipers 20 exert on the debris. Once agglomerated, for example into threads or roughly cylindrical masses, the agglomerated debris has a tendency to remain suspended within the liquid that the filtering cavity 11 , rather than remaining on, and thus blocking the perforated wall portion 13. In this way the filtering capacity of the filter unit 1 (i.e. the volume of debris-laden liquid that can be processed before the pressure drop across the filter unit 1 exceeds a threshold) can be increased. The sealed / airtight nature of the pump means that there is a pump pressure generated by the rotation of the wipers in the filtering configuration that helps create flow through perforated wall portion.

[0187] In order to promote agglomeration of debris, the filter unit 1 can be operated in a filtering configuration in which the rotor shaft 19 is rotated at a filtering rotation speed of 1 -2 rpm. At these low speeds, the shearing action of the wipers 20 tends to roll up and agglomerate any loose, fibrous debris accumulated on the perforated wall portion 13 (as the liquid filters through the perforated wall portion 13) into agglomerates that remain in suspension in the liquid in the filtering cavity 11 .

[0188] Because the debris filtered from the liquid passing through the perforated wall portion 13 does not sit on and block the perforated wall portion 13, smaller mesh / pore / perforation sizes can be used in the perforated wall portion than are typical for the known mesh filters, e.g. a pore size of less than 25 microns can be used.

[0189] The wiping portions 22 of the wipers 20 are compliant (i.e. formed of (elastically) deformable e.g. soft, flexible, material such as rubber) and the distance from the attached edge 21 to the wiping edge 23 of an undeformed wiper 20 is greater than the distance between the outer surface of the rotor shaft 19 to which the attached edge 21 is mounted and the perforated wall portion 13 of the cavity 11. The result of this greater distance from the attached edge 21 to the wiping edge 23 and the compliant nature of the wiping portion 22 is that the wiping portion 22 of each blade is deflected by contact with the sidewalls of the cavity 11 (e.g. the perforated wall portion 13).

[0190] By the deflection of the wiping portions 22 of the wipers 20, the contact area between the wiping portion 22 and the perforated wall portion 13 can be increased during rotation of the rotor shaft 19 and wipers 20, thereby increasing the shear force acting on debris that has accumulated on the perforated wall portion 13. This increase in shear force can increase the rate of agglomeration of the debris on the perforated wall portion 13.

[0191] The filter unit 1 further comprises a debris collection chamber 5. The debris collection chamber 5 provides a location within the filter unit 1 to which debris that has been filtered from the liquid and agglomerated by the action of the wipers 20 can be transferred from the filtering cavity 11 for storage before the collected debris is disposed of.

[0192] By providing a debris collection chamber 5 within the filter unit 1 that is separate to the filtering cavity 11 but is open thereto, it is possible for debris to be removed from the filtering cavity 11 without having to open the filter unit 1 and without any user input. Thus, the filtering capacity of the filter unit 1 can be further increased because not only does the accumulated debris not block the perforated wall portion 13, but also the agglomerated debris that would otherwise remain in the filtering cavity 11 can be moved to the debris collection chamber 5 without having to open the filter unit 1 .

[0193] Similar to the filtering cavity 11 , the collection chamber 5 extends axially along the filter unit 1 between front and rear walls 16, 17. The debris collection chamber 5 is distal the perforated wall portion 13 within the filter unit 1 , that is, the collection chamber 5 is positioned vertically above the filtering cavity 11 , on an opposite side of the rotor shaft 19 to the perforated wall portion 13. Specifically, as shown in Figure 1A, the axial centre of the collection chamber 5 is vertically aligned with the axial centre 15 of the filtering cavity 11 , the axial centre 15 of the filtering cavity 11 also being coincident with the axis of rotation of the rotor shaft 19. It is also vertically aligned with the liquid inlet (not shown).

[0194] The debris collection chamber 5 is in communication with the filtering cavity 11 via a debris port 6. The debris port 6 extends from an opening 7 in the upper wall portion 14 of the filtering cavity to an exit 8 into the collection chamber 5, thereby defining a path along which debris can be transferred from the filtering cavity 11 to the debris collection chamber 5. As with the filtering cavity 1 1 , the debris exit port extends axially along the filter unit 1 between the front wall and rear walls 16, 17 of the housing 10. The debris port 6 extends from the filtering cavity 1 1 to the collection chamber 5 in a direction substantially tangentially to a circle swept by the wiping portions 22 of the wipers 20. Furthermore, it can be appreciated from Figure 1A that the debris exit port extends from the filtering cavity 1 1 to the collection chamber 5 in a direction that is around 25 degrees from vertical (in the cross-section shown in Figure 1 A).

[0195] In order to transfer agglomerated debris from the filtering cavity 11 to the collection chamber 5 via the debris port 6, the filter unit 11 is placed in the transfer configuration. The filtering cavity 11 is drained of liquid (by allowing air to bleed into the filtering cavity 11 through an air bleed (not shown)), and the rotor shaft 19 and wipers 20 are rotated first at a dewatering rotation speed of around 100 rpm and then at a transfer rotation speed of around 800 rpm. This transfer rotation speed imparts a tangential force (i.e. a force in a direction tangential to the circle swept by the wiping portions 22 of the wipers 20) on the agglomerated debris and imparts it with sufficient momentum that it can move into and through the debris port 6 and reach the collection chamber 5 i.e. the agglomerates become airborne and move against gravity to travel through the debris port 6 and into the collection chamber 5.

[0196] In order to assist debris travelling through the debris port 6 in passing through the exit 8 into the collection chamber 5, the collection chamber 5 further comprises a guiding wall 2 for guiding the path of the debris into the collection chamber 5. The guiding wall 2 defines an arc that intersects the axis of the debris port 6 such that debris travelling through the debris port 6 towards the collection chamber 5 may collide with the guiding wall 2 and thereby be slowed and deflected into the collection chamber 5, such that it then falls towards the base 3 of the collection chamber 5 under gravity.

[0197] Furthermore, to prevent debris that has been transferred into the collection chamber 5 from moving back into the debris port 6 and subsequently into the filtering cavity 11 , the collection chamber 5 is provided with a retaining wall 4 that extends upwards from the base 3 so as to provide a barrier between the collection chamber 5 and the debris port 6. The retaining wall 4 is substantially parallel to, and extends from, an inner wall 6a of the debris port 6, thereby not disrupting the passage of debris from the filtering cavity 1 1 into the collection chamber 5 by extending into the debris port 6.

[0198] It can be appreciated from Figure 1 A that the debris collection chamber 5 is provided in a pocket portion 9 formed within the housing 10. The base of the pocket portion 9 is provided by the upper wall portion 14 whilst the pocket portion 9 is defined at its upper portion by a pocket wall 9a. The pocket portion 9 extends axially between the front and rear walls 16, 17 of the housing 10 and is distal the perforated wall portion 13.

[0199] The filter unit 1 is airtight above the perforated wall portion 13 in the filtering configuration i.e. there is no airflow path into the filtering cavity 11 through any of the front and rear walls 16, 17, or through the pocket wall 9a in the filtering configuration. In this way, an air pocket can be formed within the housing 10 of the filter unit 1 because air above the perforated wall portion 13 is trapped within the housing 10. Accordingly, the liquid level in the filtering cavity 11 will not rise substantially above the upper edge of the perforated wall portion 13 because to do so would require compression of the air pocket in preference to forcing liquid already in the cavity 11 through the perforated wall portion 13. Thus, by also positioning the opening 7 of the debris port 6 and the debris collection chamber 5 vertically above the filtering cavity 11 and distal the perforated wall portion 13, the debris collection chamber 5 can remain in the air pocket and accordingly debris can dry out rather than being re-wetted by operation of the filter unit 1. To assist in the drying of the debris in the collection chamber 5, a drain (not illustrated) can be provided in the base 3 of the collection chamber 5, allowing liquid in the collected debris to drain from the chamber 5 back to the cavity 11 via a drain hole in pocket portion 9.

[0200] To allow the liquid to be drained from the cavity 11 in the dewatering and transfer configurations, the filter unit 1 further comprises an air bleed valve (e.g. a float valve or flap valve) (not illustrated) that allows air to bleed into the filtering cavity. This facilitates placing the filter unit 1 into the transfer configuration for transferring agglomerated debris into the collection chamber 5, which requires the cavity 11 to be drained of liquid. When the air bleed valve is shut, the filter unit 1 is airtight above the perforated wall portion, and when it is open, air is able to bleed into the housing 10 via the bleed valve.

[0201] It can be appreciated that continuing operation of the filter unit 1 as described above allows the perforated wall portion 13 to continue filtering the debris-laden liquid (because the perforated wall portion 13 can be cleared of debris) but will result in the collection of debris in the collection chamber 5 over time. Eventually, the collection chamber 5 will require emptying in order to provide space for more debris to be collected therein. In order to facilitate this, the collection chamber 5 is slidable relative to the housing 10 in a direction substantially parallel to the axis of the filtering cavity 11 and rotor shaft 19. This is illustrated in Figure 1 B, which shows the collection chamber 5 in place within the housing and (in dotted lines) shows the sliding movement of the collection chamber 5.

[0202] Specifically, in Figure 1 B, the collection chamber 5 slides from the housing 10 through an aperture provided in the front wall 16 of the housing 10 into the pocket 9. The axial end 5a of the collection chamber 5 sits proud of the housing 10 when fully inserted therein (as shown in solid lines in Figure 1 B) and is provided with a gripping portion 5b to allow for easy sliding of the collection chamber 5 relative to the pocket portion 9 of the housing 10.

[0203] In the filtering, dewatering and transfer configurations of the filter unit 1 , the axial end 5a of the collection chamber 5 abuts the outside surface of the front wall 16 of the housing 10 when fully inserted therein and forms a sealing interface with the housing 10 in order to provide the airtight configuration discussed above; an O-ring seal 12 on the collection chamber 5 adjacent the axial end 5a providing this sealing with the outside surface of the front wall 16 of the housing 10. In order to remove the collected debris from the collection chamber 5, the collection chamber 5 is slid from the housing 10 through the aperture in the front wall 16. The collection chamber 5 may be removed from the housing 5 thus facilitating removal of the debris from the collection chamber 5 into, for example, a bin, via an opening 5c / 5d of the collection chamber 5. An axial scraper or auger may be provided within the collection chamber 5 to assist with this removal step via the open axial end 5d of the collection chamber 5 proximal the rear wall 17. Alternatively, a radial scraper / auger may be used to scrape the debris from the collection chamber via the slotted opening 5c. Once the collected debris have been removed from the collection chamber 5, the collection chamber 5 can be re-inserted into the pocket portion 9 of the housing 10 via the same aperture such that the filter unit 1 .

[0204] Although not illustrated in Figure 1 B, in order to prevent inadvertent removal of the collection chamber 5 from the housing 10, the aperture through which the collection chamber 5 is inserted may comprise a notch for allowing passage of a locking element provided on an outer surface of the collection chamber 5. Accordingly, where the collection chamber 5 is rotatable within the housing 10 once fully inserted therein, the locking element may require alignment with said notch (e.g. in keyed arrangement) in order to allow the collection chamber 5 to be slid out from the housing 10, as otherwise the locking element may abut the housing 10 or the notch may abut the collection chamber 5. Such an arrangement may be considered a bayonet arrangement.

[0205] Figure 2 is a schematic cross-sectional drawing of a second embodiment of a filter unit 1 ’. The second embodiment can be considered a modification of the first embodiment. The forgoing description in relation to the first embodiment is applicable, mutatis mutandis, to the second embodiment, except for in relation to the differences highlighted in the discussion of the second embodiment below.

[0206] Where features of the first embodiment of the filter unit 1 and the second embodiment of the filter unit T are alike, they are indicated by equivalent reference numbers.

[0207] A first difference between the first embodiment of the filter unit 1 and the second embodiment of the filter unit T relates to the manner in which the debris collection chamber 5 is removable from the housing 10 in order to empty the collection chamber 5 of collected debris.

[0208] In the second embodiment, the collection chamber 5 is movable relative to the housing by lifting the collection chamber 5 vertically away from the housing 10 (i.e. in a direction that is not co-linear with the axis of the filtering cavity 11 / rotor shaft 19, but instead substantially perpendicular to that axis, typically vertically upwards).

[0209] The collection chamber 5 forms part of a lid 25 of the filter unit T. The lid 25 seals the filter unit T such that the filtering cavity 11 and collection chamber 5 are airtight. In Figure 2, there are side walls 26a, 26b which extend vertically from opposing ends of the perforated wall portion 13 (the perforated wall portion 13 subtending an angle of around 180 degree). Each side wall terminates with an outwardly-extending lip 27a, 27b. The lid 25 has corresponding sealing walls 28a, 28b that abut inner surfaces of the respective side walls 26a, 26b of the housing 10, and sealing lips 29a, 29b which overlay the outwardly-extending lips 27a, 27b. Seal elements 30a, 30b are interposed between the lips.

[0210] There are two upper wall portions 14a, 14b provided as part of the lid 25. These upper wall portions 14a, 14b are substantially linear and, as such, the filtering chamber does not have a substantially cylindrical cross-section. Accordingly, it is only the perforated wall portion 13 of the housing 10 that the wiping portions 22 of the wipers 20 contact on rotation of the rotor shaft 19. Moreover, the filtering cavity 11 is defined by the perforated wall portion 13 and the base 3 of the collection chamber 5, rather than by the perforated wall portion 13 and the upper wall portions 14a, 14b. The base 3 of the collection chamber 5 extends into the filtering cavity 11 (and defines the upper limit of the filtering cavity 11) from the second upper wall portion 14b.

[0211] The collection chamber 5 also forms part of the lid 25 with the guiding wall 2 joining the first upper wall portion 14a.

[0212] The opening 7 to the debris port 6 is defined between the first upper wall portion 14a and the retaining wall 4.

[0213] In order to empty the collection chamber 5, the lid 25 is removed from the housing 10 (after bleeding air into the filtering cavity 11) by vertical lifting of the lid 25 relative to the housing.

[0214] As well as allowing emptying of the collection chamber 5, the removal of the lid 25 to exposes the filtering cavity 11 so that the rotor shaft 19 and wipers 20 are exposed and can be easily cleaned of any long hairs or threads that may have become wrapped around the rotor shaft 19.

[0215] Figure 3 is a schematic cross-sectional drawing of a third embodiment of a filter unit 1 ”. The third embodiment can be considered a modification of the first embodiment. The forgoing description in relation to the first embodiment is applicable, mutatis mutandis, to the third embodiment, except for in relation to the differences highlighted in the discussion of the third embodiment below. Where features of the first embodiment of the filter unit 1 and the third embodiment of the filter unit 1 ” are alike, they are indicated by equivalent reference numbers.

[0216] A first difference between the first embodiment of the filter unit 1 and the third embodiment of the filter unit 1 ” relates to the manner in which the debris collection chamber 5 is removable from the housing 10 in order to empty the collection chamber 5 of collected debris.

[0217] In the first embodiment, the collection chamber 5 is receivable within the pocket portion 9 of the housing 10, i.e. a substantial portion of the collection chamber 5 resides within the housing 10 of the filter unit 1 , from which the collection chamber 5 can be slid for removal and emptying. In contrast, in the third embodiment, the collection chamber 6 is not received within the housing 10, but instead resides outside the housing 10 and the filter unit 1 ” comprises a sealing portion 30 between the collection chamber 5 and the filtering cavity 11. In the case of Figure 3, the sealing portion is a sealing collar 30a lined with an o-ring 30b which forms an airtight seal but which allows the collection chamber 5 to be repeatedly attached to, and detached from, the housing 10 by moving the collection chamber 5 away from the housing in a direction substantially parallel to the axis of the debris port 6, that direction being non co-linear with (e.g. perpendicular to) the axis of the filtering cavity 11 / rotor shaft 19.

[0218] Figure 4 is a schematic cross-sectional drawing of a filter cavity and a plurality of wipers mounted therein. Figures 5A and 5B show an excerpted detail from the drawing of Figure 4, illustrating details of the wiper’s construction. The wipers in Figures 4 and 5A / 5B may be employed in any of the embodiments of the filter unit described herein.

[0219] As described above in relation to Figure 1 , the wiping portion 22 of the wiper 20 may be compliant. In some embodiments, the entire wiper 20 may be compliant.

[0220] However, in the case of the three wipers 20 in Figure 4, the wiping portion 22 is the only compliant portion of the wiper 20, the wiping portion 22 being mounted on a rigid portion 24. Accordingly, where the distance from the attached edge 21 to the wiping edge 23 of an undeformed wiper 20 is greater than the distance between the outer surface of the rotor shaft 19 to which the attached edge 21 is mounted and the perforated wall portion 13, it is only the wiping portion 22 of the wiper 20 that is deflected by contact with the perforated wall portion 13.

[0221] Figures 5A / B provide and excerpted detail from the drawing of Figure 4, illustrating one possible manner in which the wiping portion 22 may be mounted on the rigid portion 24 of a wiper 20. In Figures 5A / B, the wiping portion 22 is mounted in a seat 36 provided in the end of the rigid portion 24 distal the attached edge 21 of the wiper. The seat 36 takes the form of a recess in an end face of the rigid portion 24, the recess extending along the rigid portion 42 in the axial direction of the filtering cavity 11 and being bounded by seat extensions 36a, 36b in the clockwise and anticlockwise directions of rotation of the wiper 20. The seat extensions 36a, 36b act to support the wiping portion 22 received in the seat 36. However, the seat extension 36a that acts to support the wiping portion 22 when the wiper 20 is rotating clockwise (i.e. is behind the wiping portion 22 in the direction of travel when the wiper 20 is rotating clockwise) is shorter in the radial direction than the seat extension 36b that acts to support the wiping portion 22 when the wiper 20 is rotating anticlockwise (i.e. is behind the wiping element 22 in the direction of travel when the wiper 20 is rotating clockwise). In other words, the seat 36 is asymmetrical, such that asymmetrical deflection of the wiping portion 22 can be effected.

[0222] Specifically, a greater proportion of the wiping portion 22 is able to deflect when the wiper 20 is rotating in a clockwise direction than in the anticlockwise direction, meaning the force required to deflect the part of the wiping portion 22 that exceeds the distance from the rigid portion 24 to the perforated wall portion 13 is less (since the deformation is less localised), meaning the reaction force exerted on the wiping element 22 by the perforated wall portion 13 is less and therefore less friction will be exerted on the debris accumulated thereon. This asymmetry can be exploited where the rotation direction of the wipers 20 in the transfer configuration of the filter unit is different to the rotation direction of the wipers 20 in the filtering configuration of the filter unit, since it may be desired to exert a greater force on the debris when rotating the wipers 20 in the transfer configuration than in the filtering configuration. Accordingly, to achieve this effect with the wiper 20 shown in Figures 5A / B, the transfer configuration would be for the wiper 20 to be rotated anticlockwise such that the longer seat extension 36b is behind the wiping element 22 in the direction of travel. This creates a stiffer wiping portion and a greater contact area between the wiping portion and perforated wall portion.

[0223] Figure 6 is a schematic cross-sectional drawing of a filter cavity and a plurality of wipers mounted therein. The configuration illustrated in Figure 6 may be employed in any of the embodiments of the filter unit described herein.

[0224] The arrangement of the filter cavity in Figure 6 differs from that previously shown in that the axis of rotation of the rotor shaft 19 is not co-axial with the axis 15 of the filtering cavity 11 (i.e. the axis passing through the centre of the arc defining perforated wall portion 13 and extending parallel to the perforated wall portion 13). Specifically, in Figure 6 the axis of rotation of the rotor shaft 19 is parallel to the axis 15 of the filtering cavity 11 but is offset from that axis 15 in a direction towards the perforated wall portion 13 (e.g. offset vertically downwards in Figure 6). The result of this offsetting of the rotor shaft 19 within the cavity 11 is that the wipers 20 are deflected to a greater extent when contacting the perforated wall portion 13 than when in contact with the upper wall portion 14 of the cavity 11 , meaning that as the wipers 20 are rotated and a wiper 20 transitions from contacting the perforated wall portion 13 to contacting the upper wall portion 14, the reduction in the amount of deflection of the wipers 20 imparts the released elastic deformation energy to the debris that the wiper 20 is in contact with. In this configuration the volumes between the wipers 20 in the upper portion of the filtering cavity 11 are larger than the volumes adjacent the perforated wall portion 13. Effectively, the rotor shaft 19 / wipers 20 act as a flexible vane pump. This could create higher pressures and flows as a result.

[0225] In the instance of Figure 6, the offsetting of the rotor shaft 19 is accommodated by the entirety of each wiper 20 being made compliant, allowing for greater amounts of deflection than in the case where the wipers 20 each comprise a rigid portion 24 as in Figures 4, 5a, 5b. The rotor shaft 19 may also be made compliant to accommodate offsetting of the rotor shaft 19 within the filtering cavity 11 .

[0226] Moreover, in comparison to the structure of the first embodiment in Figures 1A and 1 B, the liquid inlet 40 has been relocated from a position interposed between the rotor shaft 19 and perforated wall portion 13 on a front or rear wall of the housing 10 (e.g. vertically below the rotor shaft 19) in Figure 1 to a position above the rotor shaft 19 in Figure 6 in order to accommodate the offsetting of the rotor shaft 19 within the filtering cavity 11 .

[0227] Figures 7A and 7B show perpendicular cross-sections through yet a further embodiment of a filter unit 1 ”’ which is similar to the second embodiment in that the collection chamber 5 is defined within a lid 25. However, the lid 25 is pivotally and slidably connected to the housing 10 at a pivotal connection 45. Similar to the second embodiment, the collection chamber 5 is defined by the lid 25 which is transparent so that the contents of the collection chamber are visible. The base 3 of the collection chamber 5 also forms the upper wall 14 of the filtering cavity 11 which, along with the perforated wall portion 13 defines a substantially cylindrical filtering cavity.

[0228] Figures 7A / 7B show the filter unit 1 in situ within a washing appliance. The filter unit 1 is slidably fitted into a modified space typically occupied by the dosing drawer of the washing appliance. The pre-wash portion of the dosing drawer is replaced with the filter unit T”. The housing 10 of the filter unit T” is integrally formed with two dosing drawers 50a, 50b which sit within a dosing compartment 50 having a detergent feed 51 to the washing drum 52 of the washing appliance. The filter unit sits within a filter compartment (tank) 53 having a drain 54 which may be in fluid connection with waste or may be in fluid communication with the washing drum. As filtered liquid leaves the filtering cavity 11 via the perforated will portion 13, the drain 54 acts to feed filtered liquid to waste or back into the washing drum). The filter compartment and dosing compartment may be sealed by a door 55 which may have a handle or recess for sliding the filter unit 1 and the dosing drawers from their compartments 53, 50.

[0229] The rotor shaft 19 is operatively connected to a drive unit 60 by way of a make / brake connection 61 . The drive unit 60 is configured to drive the rotor shaft 19 as described herein. The inlet 40 of the filter cavity 11 is coupled to a liquid feed 62 in fluid communication with the washing drum for feeding debris-laden liquid into the filter cavity. The inlet 40 and the liquid feed are connected via a make / break connection.

[0230] When emptying of the debris collection chamber 5 is required, the door 55 is pulled away from the washing appliance to slide the filter unit 1 from the filer compartment 53. The lid 25 can then be pivoted to open the filtering cavity 11. The lid 25 is then slid away from and removed from the housing 10 to facilitate emptying of the collection chamber 5 via its elongate opening 5c e.g. using a radial scraper 56 which scrapes over the guiding wall 2 of the collection chamber.

[0231] Figure 8 is a flowchart illustrating a method using a filter unit according to one of the first to fifth embodiments for filtering debris from a debris-laden liquid. Optional steps in the method are indicated by the dashed outlines to the boxes containing these steps.

[0232] At step S100 the filter unit is placed in the filtering configuration such that debris-laden liquid can be supplied into the filtering cavity and the wiper(s) can be rotated at a filtering rotation speed. At step S200, the debris-laden liquid is supplied into the filtering cavity, for example via a liquid inlet or a conduit in the housing into the filtering cavity. The liquid inlet typically comprises a valve such that the flow of debris-laden liquid can be controlled (e.g. a flap valve or a solenoid-controlled valve) and flow of liquid out of the filtering cavity via the liquid inlet can be prevented.

[0233] Once debris-laden liquid is supplied into the filtering cavity, it will proceed to be filtered by the perforated wall portion of the cavity under gravity. The perforated wall portion will retain the debris and allow the liquid to flow through.

[0234] The filtration of liquid through the perforate wall portion will lead to the accumulation of debris on the perforated wall portion, increasing the pressure drop from the cavity through the perforated wall portion.

[0235] Accordingly, at step S300 the wiper(s) disposed in the cavity are rotated at a filtering rotation speed of up to and including 60 rpm or 50 rpm, such as 40 or 30 rpm, for example 20 or 10 rpm or 5 rpm e.g. up to and including 4 rpm or 3 rpm, such as up to and including 2 rpm e.g. around 1 rpm. The wipers contact the debris accumulated on the perforated wall portion and exert a shear force on those debris, causing them to roll up and agglomerate. Once the debris has agglomerated, their shape and size, along with the rotating action of the wipers, keeps them in suspension in the liquid in the filtering cavity, thereby preventing them from clogging the perforated wall portion. Typically, the wipers are rotated by a controller sending a control signal to a drive unit (e.g. motor / gear box) that is connected to a rotor shaft that the wipers are mounted on.

[0236] Subsequently, it may be desired to transfer the agglomerated debris from the filtering cavity to the debris collection chamber, for example, if the amount of agglomerated debris in the chamber has become too high and the filter unit is no longer efficiently filtering the debris-laden liquid, i.e. the flow rate has dropped. In order to do so, at step S400 the filtering cavity is drained of liquid, typically by shutting off the supply of liquid to the cavity and opening an air bleed valve or otherwise supplying air to the cavity such that the pressure inside and outside the cavity can be equalised as the remaining liquid in the cavity drains out through the perforated wall portion.

[0237] Having drained the filtering cavity, it may be beneficial to also reduce the amount of water adsorbed into the debris within the filtering cavity. Accordingly, at step S500, the filter unit is placed into a de-watering configuration, then allowing step S600 of rotating the wipers at a de-watering rotation speed to be conducted. The de-watering rotation speed promotes the de-watering of the debris in the cavity. The dewatering rotation speed is preferably faster than the filtering rotation speed and slower than the transfer rotation speed. The de-watering rotation speed may be greater than 5 rpm, e.g. between 20-100 rpm, such as between 30 and 80 or 40 and 70 rpm, such as between 50 and 60 rpm. De-watering the debris generally makes the debris less moist, making its transfer to the collection chamber easier, and results in less liquid accumulating in the collection chamber. Subsequently, at step S700 the filter unit is placed in the transfer configuration, then allowing the wipers to be rotated at the transfer rotation speed at step S800. The transfer rotation may be in the same or opposite direction to the filtering rotation, depending on the positioning and orientation of the debris exit port. The transfer rotation speed is preferably faster than the filtering rotation speed. The transfer rotation speed may be greater than 60 rpm, e.g. greater than 100 rpm or 250 rpm, such as greater than 300, 400, 500, 600 ,700 or 800 rpm e.g. around 850 rpm. At these higher speeds and in the absence of liquid in the filtering cavity, the agglomerated debris within the housing can be flung tangentially from a wall of the filtering cavity and into the collection chamber via the debris exit port. In this manner, the amount of agglomerated debris in the filtering cavity can be reduced such that it is possible to return to step S100 to re-commence using the filter unit to filter debris-laden liquid.

[0238] However, debris will accumulate in the collection chamber 5 over time. Eventually, the collection chamber 5 will require emptying in order to provide space for more debris to be collected therein. In order to facilitate this, step S900 of removing the debris collection chamber from the housing of the filter unit can be conducted so that the debris accumulated in the collection chamber can be removed, for example, into a bin. Once emptied, the debris collection chamber may be returned to the housing.

[0239] Following step S900, the method may also return to step S100 to re-commence using the filter unit to filter debris-laden liquid.

[0240] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised.

[0241] While the disclosure includes exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the scope of the claims.

[0242] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0243] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0244] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0245] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%.

Claims

Claims:1 . A filter unit for filtering debris from debris-laden liquid, the filter unit comprising: a housing at least partly defining a filtering cavity, the housing comprising a perforated wall portion forming the base of the filtering cavity for accumulation of debris in a filtering configuration, a debris collection chamber in communication with the filtering cavity via a debris port, wherein the filter unit is airtight above the perforated wall portion in at least the filtering configuration and wherein at least an opening from the filtering cavity into the debris port is above the perforated wall portion.

2. A filter unit according to claim 1 wherein the debris port and / or the debris collection chamber is above the perforated wall portion.

3. A filter unit according to claim 1 or 2 wherein the filter unit further comprises at least one wiper mounted within the filtering cavity for wiping the perforated wall portion and wherein the filter unit has a transfer configuration in which the at least one wiper is rotatable for transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris port.

4. A filter unit according to claim 3 wherein, the at least one wiper is rotatable at a first rotation speed and at a second rotation speed, the second rotation speed being greater than the first rotation speed.

5. A filter unit according to claim 3 or 4 wherein the at least one wiper is rotatable in a first rotation direction and in a second opposing rotation direction.

6. A filter unit according to claim 5 wherein the at least one wiper comprises a compliant wiping portion for wiping the perforated wall portion and wherein, the at least one wiper is rotatable in the first rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion; the at least one wiper is rotatable in an opposing second rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion; and the first contact surface of the wiping portion may have a different area than the second contact surface of the wiping portion.

7. A filter unit according to any one of claims 1 to 6 wherein the debris collection chamber is moveable relative to the housing in an emptying configuration.

8. A filter unit for filtering debris from debris-laden fluid / liquid, the filter unit comprising: a housing at least partly defining a filtering cavity, the housing comprising a perforated wall portion for accumulation of debris, at least one wiper mounted within the filtering cavity for wiping the perforated wall portion, a debris collection chamber in communication with the filtering cavity via a debris port, wherein the filter unit has a filtering configuration in which the at least one wiper is rotatable at a filtering rotation speed; wherein the filter unit has a transfer configuration in which the at least one wiper is rotatable at a transfer rotation speed for transferring accumulated debris from the filtering cavity to the debris collection chamber; and wherein the debris collection chamber is moveable relative to the housing in an emptying configuration.

9. A filter unit according to claim 7 or 8 wherein the debris collection chamber is pivotable, liftable or slidable relative to the housing.

10. A filter unit according to claim 9 wherein the debris collection unit is slidably removable from the housing.

11. A filter unit according to claim 10 wherein the debris collection chamber is within or forms part of a lid which forms an airtight seal with the housing in the filtering configuration but which is movable to open the filtering cavity in the emptying configuration.

12. A filer unit according to claim 11 wherein the lid is pivotally mounted to the housing.

13. A filter unit according to claim 8 wherein the transfer rotation speed is greater than the filtering rotation speed.

14. A filter unit for filtering debris from debris-laden fluid / liquid, the filter unit comprising: a housing at least partly defining a filtering cavity, the housing comprising a perforated wall portion for accumulation of debris, at least one wiper mounted within the filtering cavity for wiping the perforated wall portion,a debris collection chamber in communication with the filtering cavity via a debris port, wherein the filter unit has a filtering configuration in which the at least one wiper is rotatable at a filtering rotation speed; wherein the filter unit has a transfer configuration in which the at least one wiper is rotatable at a transfer rotation speed for transferring accumulated debris from the filtering cavity to the debris collection chamber; and wherein transfer rotation speed is greater than the filtering rotation speed.

15. A filter unit according to claim 4, 13 or 14 wherein the first / filtering rotation speed is between 1-60 rpm and the second / transfer rotation speed is greater than 60 rpm.

16. A filter unit according to claim 15 wherein the transfer rotation speed is greater than 500 rpm.

17. A filter unit according to claim 14 wherein the at least one wiper is rotatable in a first rotation direction and in a second opposing rotation direction.

18. A filter unit according to claim 17 wherein the at least one wiper comprises a compliant wiping portion for wiping the perforated wall portion and wherein, the at least one wiper is rotatable in the first rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion; the at least one wiper is rotatable in an opposing second rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion; and the first contact surface of the wiping portion may have a different area than the second contact surface of the wiping portion.

19. A filter unit for filtering debris from debris-laden fluid / liquid, the filter unit comprising: a housing at least partly defining a filtering cavity, the housing comprising a perforated wall portion for accumulation of debris, at least one wiper mounted within the filtering cavity and having a compliant wiping portion for wiping the perforated wall portion, wherein the at least one wiper is rotatable in a first rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion;wherein the at least one wiper is rotatable in an opposing second rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion; and wherein the first contact surface of the wiping portion has a different area than the second contact surface of the wiping portion.

20. A filter unit according to claim 19 wherein the first contact surface area is less than the second contact surface area.

21. A filter unit according to claim 19 or 20 wherein the first rotation direction is a filtering rotation direction effected in a filtering configuration of the filter unit in which the wiping portion is flexed in the first flex direction during filtering of the debris-laden fluid / liquid.

22. A filter unit according to claim 21 wherein the filter unit further comprises a debris collection chamber in communication with the filtering cavity via a debris port, the filter unit has a transfer configuration in which the at least one wiper is rotatable for transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris port and, the second rotation direction isa transfer rotation direction effected in the transfer configuration of the filter unit in which the wiping portion is flexed in the second flex direction during transfer of the accumulated debris.

23. A filter unit according to any one of claims 14 or 22 wherein the debris collection chamber is movable relative to the housing in the emptying configuration24. A filter unit according to any one of claim 19 to 23 wherein the at least one wiper is rotatable at a first rotation speed in the first rotation direction and at a second rotation speed in the second rotation direction, the second rotation speed being greater than the first rotation speed.

25. A filter unit according to any one of claims 4 to 6 or 24 wherein the at least one wiper is rotatable at a dewatering rotation speed in a dewatering configuration at a rotation speed intermediate to the first / fi Itering rotation speed and the second / transfer rotation speed.

26. A filter unit according to any one of claims 6, 18 and 19-25 wherein the at least one wiper comprises a rigid portion having an asymmetric seat, the compliant wiping portion mounted in the seat of the rigid portion.

27. A filter unit according to any one of claims 8 to 26 wherein the perforated wall portion forms the base of the filtering cavity for accumulation of debris in the filtering configuration, the filter unit is airtight above the perforated wall portion, and at least the opening to the debris port is above the perforated wall portion.

28. A filter unit according to any one of the preceding claims wherein the housing is a static housing.

29. A filter unit according to any one of the preceding claims wherein the perforated wall portion defines an arc subtending an angle of between 90 and 250 degrees.

30. A filter unit according to any one of the preceding claims wherein the perforated wall portion has a mesh size of 60 microns or less.

31. A filter unit according to any one of the preceding claims further comprising a sensor for detecting pressure and / or liquid level within the filtering cavity.

32. A filter unit according to any one of claims 1-18 or 22-31 wherein the debris port extends from the filtering cavity at any angle of between 10 and 80 degrees from vertical in a cross-section transverse to an axial extension of the filtering cavity.

33. A filter unit according to any one of claims 1-18 or 22-23 wherein the debris collection chamber comprises an axial or radial scraper or auger.

34. A washing and / or drying appliance comprising a filter unit according to any one of the preceding claims.

35. A washing appliance according to claim 34 comprises one or more of: a drive unit comprising a connector spindle for releasable operative coupling to a rotor shaft of the filter unit; a liquid feed for releasable connection to a liquid inlet of the filter unit for delivery of debris-laden liquid into the filtering cavity; and / or a drain feed in fluid communication with the perforated wall portion of the housing.

36. A method of using the filter unit according to any one of claims 1 to 33 for filtering debris from a debris-laden liquid, the method comprising: supplying debris-laden liquid into the filtering cavity to accumulate debris on the perforated wall portion in the filtering configuration, draining the filtering cavity; and transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris port,wherein the filter unit is airtight above the perforated wall portion in at least the filtering configuration and wherein at least an opening from the filtering cavity into the debris port is above the perforated wall portion.

37. The method claim 36 wherein the filter unit further comprises at least one wiper mounted within the filtering cavity and the method comprises rotating the at least one wiper at a filtering rotation speed to agglomerate debris collected on the perforated wall portion in a filtration configuration and wherein the method further comprises rotating the at least one wiper at a transfer rotation speed for transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris exit port in a transfer configuration, the transfer rotation speed being greater than the filtering rotation speed.

38. The method of claim 37 wherein the at least one wiper comprises a compliant wiping portion for wiping the perforated wall portion and the method comprises rotating the at least one wiper in a first rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion and rotating the at least one wiper in an opposing second rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion, wherein the first contact surface of the wiping portion may have a different area than the second contact surface of the wiping portion.

39. The method of any one of claims 36 to 38 further comprising moving the debris collection chamber relative to the housing in a emptying configuration.

40. A method of using the filter unit according to any one of claims 1 to 33 for filtering debris from a debris-laden fluid / liquid, the method comprising: supplying debris-laden fluid / liquid into the filtering cavity rotating the at least one wiper at the filtering rotation speed to agglomerate debris collected on the perforated wall portion, optionally draining the filtering cavity; rotating the at least one wiper at the transfer rotation speed for transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris exit port; and moving the debris collection chamber relative to the housing for emptying the debris collection chamber.

41. The method of claim 40 wherein the transfer rotation speed is greater than the filtering rotation speed.

42. A method of using the filter unit according to any one of claims 1 to 33 for filtering debris from a debris-laden fluid / liquid, the method comprising: supplying debris-laden fluid / liquid into the filtering cavity rotating the at least one wiper at the filtering rotation speed to agglomerate debris collected on the perforated wall portion, optionally draining the filtering cavity; and rotating the at least one wiper at the transfer rotation speed for transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris exit port, wherein transfer rotation speed is greater than the filtering rotation speed.

43. A method according to any one of claims 40 to 42 wherein the at least one wiper comprises a compliant wiping portion for wiping the perforated wall portion, the method comprises rotating the at least one wiper in a filtering rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion in the filtering configuration, rotating the at least one wiper in an opposing transfer rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion in the transfer configuration, wherein the first contact surface of the wiping portion has a greater area than the second contact surface of the wiping portion.

44. A method of using the filter unit according any one of claims 1 to 33 for filtering debris from a debris-laden fluid / liquid, the method comprising: supplying debris-laden fluid / liquid into the filtering cavity rotating the at least one wiper in a first rotation direction with the wiping portion flexed in a first flex direction to provide a first contact surface in contact with the perforated wall portion, optionally draining the filtering cavity; and rotating the at least one wiper in an opposing second rotation direction with the wiping portion flexed in an opposing second flex direction to provide a second contact surface in contact with the perforated wall portion, wherein the first contact surface of the wiping portion has a different area than the second contact surface of the wiping portion.

45. The method of claim 44 wherein the first contact surface area is greater than the second contact surface area.

46. The method of claim 44 or 45 wherein the first rotation direction is a filtering rotation direction effected in a filtering configuration of the filter unit in which the wiping portion is flexed in the first flex direction during filtering of the debris-laden liquid, and wherein the filter unit further comprises a debris collection chamber in communication with the filtering cavity via a debris port, the method comprising rotating the at least one wiper in a transfer configuration for transferring accumulated debris from the filtering cavity to the debris collection chamber via the debris port, the second rotation direction being a transfer rotation direction effected in the transfer configuration of the filter unit in which the wiping portion is flexed in the second flex direction during transfer of the accumulated debris.

47. The method of any one of claims 33 to 43 or 46 further comprising removing debris from the collection chamber using an axial or radial scraper or auger.

48. The method of any one of claims 44 to 47 comprising rotating the at least one wiper at a first rotation speed in the first rotation direction and at a second rotation speed in the second rotation direction, the second rotation speed being greater than the first rotation speed.

49. The method of any one of claims 40 to 48 wherein the filter unit is airtight above the perforated wall portion in at least the filtering configuration and wherein at least an opening from the filtering cavity into the debris port is above the perforated wall portion.

50. The method of any one of claims 42 to 49 comprising moving the debris collection chamber relative to the housing in the emptying configuration.

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