This application claims priority from GB2113460.6 filed 21 September 2021 the contents of which are herein incorporated by reference for all purposes.

Field of the Disclosure

The present disclosure relates to a filter unit for the separation of particulate matter from particulate-laden liquid and a washing apparatus including the filter unit. The present disclosure also relates to a method of filtering particulate matter from particulate-laden liquid.

Background

Many industries include processes where particulate matter has to be separated from a fluid before the fluid, typically water, is discharged into a drain or recirculated for further use.

For example, sewage treatment requires the removal of particulate matter from the incoming effluent before discharge of the filtered water into rivers.

Another example is the food industry where vegetables need to be washed before they can be processed. The soil and sediment cleaned from the vegetable contaminates the wash water which then needs to be filtered before it can be either reused or discharged.

A yet further example is textile processing and washing, both domestic and commercial, where water and chemicals are used to condition or wash fabric or garments. The effluent from this process can contain a range of particulates including many thousands of microscopic fibres which enter the water cycle and contaminate rivers and seas.

Concern is growing about the long-term damage to rivers, seas and aquatic life caused by the discharge of contaminated water. Where water is discharged to a drain there are increasingly strict requirements that limit the type and amount of contaminants in the discharged water. Also, as water becomes scarcer, there is increasing pressure to recycle and reuse water rather than discharge it to a drain.

Many types of filter exist to remove contaminants in a fluid. These filters usually feature a barrier filter arrangement (typically a mesh or a bag) to remove impurities from the effluent before it is discharged or reused. Barrier filters require regular cleaning or replacement of the filter medium in order to operate effectively and not to block. Manual removal of the accumulated particulate matter is inconvenient and messy. In addition, because the matter is either wet or damp, and can remain in the filter for some time, it provides the perfect breeding ground for bacteria which can be injurious to health. In order to fully clean mesh or bag filters, it is necessary to wash the filter - which results in particulate matter entering the drain.

Centrifugal separators have long been known to be effective at filtering particulate matter from a fluid without suffering from blockages. However, emptying of the collected debris can also be problematic. The debris captured in a centrifugal separator is usually mixed with an amount of residual water. If the separator is operated intermittently the combined debris and residual water results in a dilute effluent which is more difficult to dispose of than a concentrated effluent. It is therefore desirable to concentrate the effluent as far as is possible into a sludge or a paste in order to make disposal easier.

There is a desire to develop a filter that is more easily drained.

Summary

According to a first aspect, there is provided a filter unit for separation of particulate matter from particulateladen liquid, the filter unit comprising: a chamber defined by an upper axial end wall and an opposing lower axial end wall and a peripheral particle collection wall, the upper and lower axial end walls being spaced by the peripheral particle collection wall, the chamber being rotatable about an axis of rotation so as to impart rotational motion to the liquid; an inlet for delivering particulate-laden liquid into the chamber; and an outlet for discharging filtered liquid from the chamber; wherein the chamber comprises at least one drain hole in the upper and/or lower axial end wall; and wherein the filter unit further comprises at least one a rotatable member or at least one slidable member, the/each rotatable member being rotatable or the/each slidable member being slidable between a closed configuration in which the drain hole(s) is/are obscured and an open configuration in which the drain hole(s) is/are at least partly unobscured.

By providing one or more rotatable/slidable members for opening and closing one or more drain holes, the filter can easily be drained by simple rotation/sliding of the member(s). A rotatable/slidable member is simple to manufacture, reliable in operation, and can be operated whilst the filter is rotating which ensures the particulate matter remains in the filter during the de-watering/draining operation.

Optional features will now be set out. These are applicable singly or in combination with any aspect.

In some embodiments, the outlet is provided in the upper or lower axial end wall (hereinafter referred to as the upper or lower end walls).

There may be one or more e.g. two drain holes which may be in the same axial end wall as the outlet.

Where there are two (or more) drain holes, they may be opposed (e.g. diametrically opposed) across the central longitudinal axis of the chamber.

There may be a series of drain hole(s) spaced (e.g. equally spaced) in a circumferential direction around the upper or lower end wall.

The drain hole(s) and outlet may be in the upper end wall.

The drain hole(s) may be tapered e.g. tapered from an inner surface to an outer surface of the upper/lower end wall. In this way, the transverse cross-sectional dimensions (e.g. diameter) of the drain hole(s) may increase towards the outer surface. The drain hole(s) e.g. the drain hole(s) in the upper end wall may be radially spaced from the central longitudinal axis of the chamber. Each of the two or more (e.g. the series of) drain holes may be equally radially spaced from the central longitudinal axis of the chamber. The radial spacing between the central longitudinal axis of the chamber and the drain hole(s) may be larger than the radial spacing between the drain hole and the particle-collection wall (hereinafter referred to as the collection wall).

The radial spacing between the central longitudinal axis of the chamber and the drain hole(s) may be larger than the radial spacing between the central longitudinal axis of the chamber and the outlet i.e. the outlet may be radially interposed between the central longitudinal axis of the chamber and the drain hole(s).

The drain hole(s) may be radially spaced from the collection wall. In use, the radial spacing between the drain hole(s) (e.g. the drain hole(s) in the upper end wall) and the collection wall may define a dewatering liquid level. By providing one or more drain holes that is/are radially spaced from the collection wall, the chamber can advantageously be drained and still leave some residual liquid in the chamber such that the particulate matter may be concentrated to a slurry or paste.

The filter unit may comprise at least one a rotatable member that is moveable (rotatable) between a closed configuration in which the/each drain hole is obscured (by the rotatable member) and an open configuration in which the/each drain hole is at least partly unobscured.

In other embodiments, the filter unit may comprise at least one a slidable member that is moveable (slidable) between a closed configuration in which the/each drain hole is obscured (by the slidable member) and an open configuration in which the/each drain hole is at least partly unobscured.

In the open configuration, the drain hole(s) is/are at least partially unobscured e.g. fully unobscured in order to allow liquid to drain out of the chamber.

In some embodiments, the or each rotatable/slidable member has at least one aperture that is rotatable/slidable into and out of alignment with the drain hole(s).

Thus in the closed configuration, the aperture(s) is/are un-aligned with the drain hole(s) but in the open configuration, the aperture(s) is/are at least partly e.g. fully aligned with the drain hole(s). The/each aperture may have dimensions matching those of the drain hole(s) e.g. matching the dimensions (e.g. diameter) of the drain hole(s) at the outer surface of the end wall on which the drain hole is provided.

The/each rotatable/slidable member may be mounted on the outer surface of the upper/lower end wall (i.e. the surface facing outwards from the chamber). The/each rotatable/slidable member may be rotatable/slidable relative to the upper/lower end wall of the chamber.

The rotatable member may comprise a disc e.g. a substantially circular disc or the rotatable member may comprise an annulus.

The axis of rotation of the rotatable member(s) may be parallel to the central longitudinal axis of the chamber i.e. the rotatable member(s) may (each) have an axis of rotation parallel to the axis of rotation of the chamber. In these embodiments, the axis of rotation of the rotatable member(s) may transect the upper/lower ends walls of the chamber. The slidable member may comprise an elongated slider having an elongate axis aligned with a sliding axis of the slider. The sliding axis of the/each slider is preferably perpendicular to the central axis of the chamber. The sliding axis is preferably spaced laterally/rad ial ly spaced from the central axis of the chamber i.e. does not transect the central axis.

The rotatable member(s) may be mounted on the outer surface of the upper/lower end wall via one or more mounting pins extending through the rotatable member into a respective receiving hole on the outer surface of the upper/lower end wall.

For the/each rotatable member comprising a rotatable disc, there may be a respective mounting pin extending through the geometric/axial centre of the disc.

The annular rotatable member may be mounted using one or more mounting pins (e.g. two mounting pins) extending through the annulus within a respective circumferentially-extending slot. In this way, the annular rotatable member can rotate by moving relative to the mounting pin(s) in the slot(s).

The slider may be mounted within a slot or channel on the outer surface of the upper/lower end wall. The slot may be an elongated slot having an elongate axis coincident with the sliding axis of the slider. The elongate slot may have an elongate length greater than an elongate length of the slider so that the slider can slide within the slot. The drain hole is also provided within the slot so that it can be covered/uncovered by sliding of the slider.

The slot may extend partly along a portion of a chord of a circular upper/lower end wall. Where there are multiple slidable members/slots, the slot may be parallel to each other and may be diametrically opposed.

The slider is connected to a first axial end of the slot by a biasing member (e.g. a resilient member such as a spring). The biasing member biases the sliding member towards the second axial end of the slot such that the aperture of the slider is out of alignment with the drain hole i.e. the drain hole is closed.

In some embodiments, the filter unit further comprises an actuator for effecting rotation/sliding of the/each rotatable/slidable member to move the rotatable/slidable member(s) between the open and closed configurations. The actuator is configured to interact with the/each rotatable/slidable member by applying a force to the rotatable/slidable member(s). The interaction may be direct e.g. through contact between the actuator and the/each rotatable/slidable member or the interaction may be indirect e.g. with no contact between the actuator and the/each rotatable/slidable member. The force may be, for example, a contact or frictional force or a non-contact force e.g. a magnetic force (e.g. through electromagnetic induction).

A non-contact force does not require the actuator to contact the rotatable/slidable member, which prevents wear of the components moving relative to each other while still providing actuation. Preventing wear of the actuator and/or rotatable/slidable member improves the lifespan of the components and avoids contamination of the filtered water leaving the filter.

In some embodiments, the filter unit includes a chamber housing for housing the filter unit chamber and the actuator is provided on the chamber housing. The drain hole(s) may be fluidly connected to the chamber housing. The chamber housing may have an outlet that may be fluidly connected to a drain. The chamber housing may comprise upper and lower axial end walls adjacent (e.g. parallel to) the upper and lower ends walls of the filter chamber.

In some embodiments, the actuator comprises: an external portion e.g. a handle portion external to the chamber housing e.g. mounted on an outer surface of the upper or lower axial end wall of the chamber housing; an actuating element internal to the chamber housing; and a connecter portion extending through the chamber housing e.g. through the upper or lower axial end wall of the chamber housing to connect the external/handle portion and actuating element.

In some embodiments, the actuating element may be movable e.g. by movement of the external/handle portion towards the rotatable/slidable member(s). The actuating element may be movable into contact with the rotatable/slidable member(s). The actuating element may be axially moveable or radially moveable (e.g. radially slidable) towards e.g. into contact with the rotatable/slidable member. The actuating element may be axially moveable towards e.g. into contact with an upper surface of the rotatable/slidable member e.g. with an upper surface of the annular rotatable/slidable member. The actuating element may be radially slidable into contact with at least one boss upstanding from the surface of the rotatable/slidable member, e.g. from the surface of the rotatable disc member.

In some embodiments, the actuator may comprise a magnet. The actuator may comprise a permanent magnet or an electromagnet. For example, the actuator may comprise a magnetic actuating element (formed of a ferromagnetic material) which may be a permanent or electromagnet.

In these embodiments, the rotatable/slidable member(s) may be at least partly conductive. For example, the rotatable/slidable member(s) may be at least partly formed of a conductive material such as a metal. In some embodiments, the rotatable member may comprise a conductive annular plate e.g. a metal annular plate. The slidable member may comprise a conductive elongated slider which may be a metal slider. The rotatable/slidable member may additionally or alternatively comprise conductive protrusions upstanding from the rotatable/slidable member(s). In close proximity to the conductive rotatable/slidable member(s) and/or conductive protrusions, the magnetic actuating element creates drag on the rotatable/slidable member(s) due to a magnetic force e.g. an electromagnetic force.

The magnetic actuating element may be axially moveable towards the rotatable/slidable member(s) without making direct contact with the rotatable/slidable member(s) e.g. moveable into close proximity with the conductive rotatable/slidable member. For example, the magnet may be connected to a handle portion (e.g. via a connector portion extending through the chamber housing). The magnet may be axially moveable towards the conductive rotatable/slidable member. At close proximity to the conductive rotatable/slidable member and/or conductive protrusions, the permanent magnet will create a drag in the rotatable/slidable member(s) e.g. in the metal annular plate or metal slider as described above.

In other embodiments, the magnetic actuating element may be axially moveable towards the conductive rotatable/slidable member using a solenoid. For example, the external portion of the actuator may comprise an electrical power supply configured to supply an electrical current to the solenoid and the magnetic actuating element may be movable e.g. by supplying the electrical current to the solenoid. The solenoid may move the magnetic actuating element towards the conductive rotatable/slidable member when activated by the electrical current so that the magnet creates a drag in the rotatable/slidable member(s) as described above.

In yet further embodiments, where the actuator comprises an electromagnet, the external portion may comprise an electrical power supply for supplying an electric current to a coil wound around a ferrous core.

The coil may be external to the chamber housing. The ferrous core may extend into chamber housing through the upper axial end wall.

In some embodiments, the ferrous core may comprise two radially spaced extensions extending from the ferrous core through the chamber housing. In these embodiments, the electrical power supply may be configured to supply an electrical current to the coil which magnetises the ferrous core and extensions. The radial spacing between the extensions may be occupied by the conductive protrusions upstanding from the rotatable member(s). The electromagnet may be axially fixed relative to the rotatable/slidable member. Upon energisation of the electromagnet, the magnetised extensions of the ferrous core may create a drag in the rotatable/slidable member as a result of the electromagnetic induction in the conductive protrusions.

In some embodiments, where the filter unit comprises multiple drain holes, the filter unit also comprises multiple rotatable/slidable members, each rotatable/slidable member associated with a respective drain hole. In some embodiments, each rotatable member may be a disc member rotateably mounted (on its mounting pin) adjacent the respective drain hole. Each rotatable disc member will comprise a respective aperture for alignment (in the open configuration) with the respective drain hole. In other embodiments, each slidable member may be an elongated slider slidably mounted in a respective slot housing the respective drain hole. Each slider will comprise a respective aperture for alignment (in the open configuration) with the respective drain hole within the respective slot.

In other embodiments where the filter unit comprises multiple drain holes, the filter unit comprises a single rotatable member, e.g. a single annular rotatable member (which may be a single conductive annular rotatable member). In these embodiments, the annular rotatable member may rotateably mounted (on its mounting pins) with its axial centre coincident with the central longitudinal axis of the filer chamber. The rotatable disc member will comprise a plurality of apertures, each for alignment (in the open configuration) with a respective one of the plurality of drain holes.

In some embodiments (e.g. where the/each drain hole has an associated rotatable member) where the actuating element is radially slidable, the actuating element may comprise two downwardly depending radially spaced tabs (i.e. spaced in a direction perpendicular to the central longitudinal axis of the chamber).

The rotatable member(s) (e.g. rotatable disc member(s)) may each comprise two bosses upstanding from the surface of the rotatable member. The two tabs protrude and the two bosses upstand sufficiently that there is a common plane perpendicular to the central longitudinal axis of the chamber through which both the actuating element tabs and rotatable member bosses pass i.e. there is overlap in an axial direction between the actuating element tabs and the bosses of the rotatable member(s).

The angle between the two bosses may be between 30 and 180 degrees e.g. around 120 degrees. The actuating element has a rest configuration in which the tabs are spaced from the bosses e.g. rest either side of the bosses on the rotatable member(s) so that there is no contact between the tabs and bosses.

To effect rotation of the rotatable member(s) to close the drain hole(s) (so that the filter unit can be used to filter liquid), the external/handle portion of the actuator is used to slide the actuating element so that a first of the tabs is in the path of a first of the bosses on the/each rotatable member(s) as the rotatable member(s) rotate(s) with the upper/lower axial walls. The circumferential contact between the first tab and the first boss(es) in its path rotates the/each rotatable member (e.g. on its respective mounting pin) by knocking the first boss(es) out of the path of the first tab. As the/each rotatable member rotates, the aperture in the rotatable member is moved out of alignment with the respective drain hole so that liquid cannot exit the drain hole.

To effect rotation of the rotatable member(s) to open the drain hole(s) (so that the filter unit can be drained), the external/handle portion of the actuator is used to slide the actuating element so that a second of the tabs is in the path of the second of the bosses on the/each rotatable member(s) as the rotatable member(s) rotate(s) with the upper/lower axial walls. The circumferential contact between the second tab and the second boss(es) in its path rotates the/each rotatable member (e.g. on its respective mounting pin) by knocking the second boss(es) out of the path of the second tab. As the/each rotatable member rotates, the aperture in the rotatable member is moved into alignment with the respective drain hole so that liquid can exit the drain hole.

In other embodiments where the actuating element is axially moveable towards e.g. into contact with or proximal the rotatable/slidable member, the actuating element may be biased out of contact with or distally from the rotatable/slidable member(s). For example, the actuator may comprise a resilient element (such as a spring) to bias the actuating element out of contact or distally from with the rotatable/slidable member(s). The resilient element may be provided externally to the housing chamber, for example, it may be interposed between the housing chamber and the external/handle portion of the actuator. In some embodiments, the resilient member (e.g. spring) may be coiled around the connecting portion of the actuator with a lower end in abutment with the housing chamber and an upper end in abutment with the handle portion of the actuator so that the handle portion is biased away from the housing chamber thus pulling the actuating element away from and/or out of contact with the rotatable/slidable member(s).

In these embodiments, there may be a single rotatable member comprising an annulus e.g. mounted on one or more (e.g. two) mounting pins seated within circumferentially-extending slots.

The rotatable member (e.g. the single annular rotatable member - which may be a conductive annular member) or slidable member may be biased towards its closed configuration with the drain hole(s) blocked. For example, the filter unit may comprise at least one biasing element e.g. at least one resilient spring. This may be as discussed above for the slidable member. For the rotatable member, it may be connected between the upper/lower axial end wall of the filter and the rotatable member for biasing the rotatable member into its closed configuration. The/each biasing element, e.g. resilient spring may extend in a circumferential direction e.g. within a respective circumferential channel provided in the rotatable member or the axial end wall. One axial end of the/each biasing element/resilient spring may be connected to the rotatable member with the other end(s) connected to the axial end wall.

In some embodiments, the rotatable member may have one or more stop elements to limit a range of rotation (e.g. through an angle of around 10 degrees) of the rotatable member. The stop element(s) may protrude in a radial direction e.g. within a respective circumferential channel provided in the axial end wall.

The actuator may be configured to create drag (e.g. through contact/friction/non-contact force) to pull on the rotatable/slidable member e.g. against the bias of the biasing element/resilient spring so that the rotatable/slidable member moves (e.g. the rotatable member moves through an angle of around 10 degrees) relative to the axial end wall into its open configuration in which the aperture(s) are moved into alignment with the drain hole(s).

In some embodiments, e.g. where the rotatable/slidable member is not biased towards its closed (or open) configuration, the transition between the open configuration and the closed configuration is determined by reversing the direction of rotation/sliding of the rotatable/sliding member e.g. in the presence of the drag which pulls on the rotatable/sliding member in a direction that opposes the direction of rotation/sliding.

The rotatable/slidable member may be sunk into the upper surface of the axial end wall so that its surface is flush with the outer surface of the axial end wall.

In some embodiments, the filter unit comprises a flow path from the inlet to the outlet and the flow path includes a radial component from the inlet to the peripheral particle collection wall and an axial component along the peripheral particle collection wall.

By providing a filter unit with a flow path that includes a radial component from the inlet to the peripheral particle collection wall and an axial component along the collection wall, particulate-laden liquid can enter the rotating chamber and flow from the inlet towards the collection wall and subsequently along the collection wall before exiting the chamber via the outlet. As the particulate-laden liquid passes axially along the collection wall, particulate matter (e.g. fibres, micro-fibres, particles etc.) within the liquid is subjected to large centrifugal forces and is therefore deposited on the collection wall so that the liquid exiting the filter unit at the outlet is substantially free of particulate matter.

The flow path axial component may be adjacent (e.g. directly adjacent) the collection wall. The flow path axial component may be parallel to the collection wall.

The radial component may be adjacent the lower end wall.

The inlet and the outlet may be axially spaced. The inlet may be at (or proximal) the lower end wall and the outlet at (or proximal) the upper end wall. In these embodiments, the flow path will include an axially upwards component along the collection wall. As the chamber rotates, the liquid will include a circumferential component (around the axis of rotation), i.e. the liquid in the chamber rotates to create a vortex. The liquid vortex in the rotating chamber enables the liquid to travel upwards from the inlet to the outlet. The axial spacing between the inlet and the outlet may be the axial length of the chamber (e.g. the inlet may be an aperture at the upper end wall and the outlet an aperture at the lower end wall or vice versa). In other embodiments, the axial spacing between the inlet and the outlet may be less than the full axial length of the chamber, for example the axial spacing may be less than 90%, less than 75%, less than 50%, less than 25%, less than 5% of the axial length of the chamber. Generally speaking the greaterthe axial spacing, the better the separation of fine particulate matter.

The filter unit may include a guide surface from the inlet to the collection wall.

The guide surface may be configured to guide the liquid radially from the inlet to the collection wall. The guide surface may extend radially from the inlet towards the collection wall (i.e. the guide surface may at least partly define the radial component of the flow path from the inlet to the collection wall).

The guide surface may be a solid (i.e. unperforated) surface. For example, in embodiments where the inlet is at (or proximal) the lower end wall, the guide surface may be an inside surface of the lower end wall. In embodiments where the inlet is at (or proximal) the upper end wall, the guide surface may be the inside surface of the upper end wall.

By including a solid guide surface between the inlet and the collection wall, the liquid introduced into the chamber is guided from the inlet to the collection wall.

In some embodiments, the filter unit may include an inlet conduit extending within the chamber (e.g. from the upper end wall) and the inlet may be a conduit opening. The inlet/conduit opening may be an open end of the inlet conduit (i.e. an opening in the axial end of the inlet conduit).

The inlet/conduit opening may be towards the lower end wall, e.g. the axial spacing between the conduit opening and the lower end wall may be smaller than the axial spacing between the conduit opening and the upper end wall, such that, in use, liquid is delivered closer to the lower end wall than the upper end wall. For example, the inlet conduit may extend within the chamber from or through the upper axial end wall towards the lower axial end wall with an opening (e.g. an end opening) within the chamber proximal the lower end wall.

The inlet conduit may extend from an opening in the upper end wall. The inlet conduit may extend through the upper end wall (i.e. the inlet conduit may extend from above the upper end wall through the upper end wall and into the chamber).

The central longitudinal axis of the inlet conduit may be coaxial with the central longitudinal axis of the chamber. The central longitudinal axis of the inlet conduit may be coaxial with the axis of rotation of the chamber.

Feed to the inlet conduit may be under gravity, by a pressure pump, or by impeller within the filter chamber. The inlet conduit may include an inlet radial flange. The inlet flange may be shaped substantially as a disc.

The inlet flange may extend radially from or proximal the axial end (e.g. the axial open end) of the inlet conduit. If the drain hole(s) are in the lower axial end wall, the inlet flange may extend radially so as to extend past the drain hole(s). The inlet flange (where present) at least partly defines the radial component of the flow path. For example, there may be a radial passage defined between the guide surface and the inlet flange.

In use, the inlet flange (and guide surface) diverts the delivered liquid radially outwards towards the collection wall of the chamber. The diverted liquid can then flow axially at a position nearer to the radially outer edge of the chamber where it will be subject to higher centrifugal forces (compared to liquid closer to the axis of rotation), therefore increasing the likelihood of particulate matter contained within the liquid being forced towards and against the collection wall. It will be appreciated that the centrifugal force increases in direct proportion to the radial spacing from the axis of rotation.

The inlet flange may be a lower flange extending proximal the lower end wall. In these embodiments, the radial flow path will extend between the upper (guide) surface of the lower end wall and the lower surface of the lower flange.

The inlet conduit may additionally or alternatively comprise an outlet flange extending radially from the inlet conduit proximal the outlet. The outlet flange may at least partly define a second radial component of the flow path e.g. from the collection wall to the outlet

In use, the outlet flange diverts the liquid radially inwards from the collection wall towards the central axis of the chamber where it can exit via the outlet.

The outlet flange may be an upper flange extending proximal the upper end wall. In these embodiments, the second radial flow path will extend between the lower surface of the upper end wall and the upper surface of the upper flange. For example, there may be a radial passage defined between the upper flange and the upper end wall.

If the drain hole(s) are in the upper axial end wall, the outlet flange may extend radially so as to extend past the drain hole(s).

In some embodiments, the filter unit may include an outlet (upper) flange and an inlet (lower) flange.

The outlet (e.g. upper) and/or inlet (e.g. lower) flange may each include a vent or bleed arrangement extending between opposing axial faces of the respective flange. The vent/bleed arrangement may be an aperture, e.g. a circular aperture, annular aperture, or a channel. It may include a bleed valve. The/each vent/bleed arrangement in the outlet/inlet flange may be about 1 ,5mm in width, for example it/they may be 3.0mm or greater. The radial spacing between the vent/bleed arrangement in the outlet/inlet flange and the inlet conduit may be smaller than the radial spacing between the vent/bleed arrangement in the outlet/inlet flange and a radially outer edge of the outlet/inlet flange. The radial spacing between the vent/bleed arrangement in the outlet/inlet flange and the inlet conduit may be smaller than the radial spacing between the outlet and the inlet conduit i.e. the vent/bleed arrangement is closer to the inlet conduit than the outlet. The upper and/or lower flanges may also be annular with the inner diameter offset from the inlet conduit.

In use, the vent/bleed arrangement may be configured to allow air to pass from one side of the flange to the other side of the flange in order to balance air pressure (and thus water levels).

The outlet/inlet flange may be a continuous or discontinuous annulus. The radial spacing between the radially outer edge of the outlet/inlet flange and the collection wall may be smaller than the radial spacing between the central longitudinal axis of the chamber/inlet conduit and the radially outer edge of the flange (i.e. the radially outer edge of the flange is closer to the collection wall than the central longitudinal axis of the inlet conduit). The distance from the axial centre of the chamber/inlet conduit to the radially outer edge of the outlet/inlet flange may be greater than 50%, greater than 60%, greater than 70%, greater than 80%, or greater than 90% (e.g. between 95-96%) of the radius of the chamber.

The outlet may be radially spaced from the axis of rotation of the chamber. The radial spacing from the axis of rotation to the outlet may be less than the radial spacing from the outlet to the collection wall.

The outlet may include a single opening or a series of openings e.g. arranged on the upper end wall. The series of openings may be symmetrically located either side of the central longitudinal axis of the chamber (i.e. diametrically opposed either side of the longitudinal axis). In other embodiments, the opening may be asymmetrically arranged either side of the central longitudinal axis. The openings may be arranged in a ring around (e.g. centred around) the central longitudinal axis of the chamber. The openings may be arranged in a ring with even circumferential spacing between the openings.

The outlet may be a continuous or discontinuous annular opening. The axial centre of the annular opening may be coincident with the central longitudinal axis of the chamber i.e. coincident with the axis of rotation.

The annular opening may surround/circumscribe the inlet conduit as the inlet conduit passes through the upper end wall.

The filter unit includes a chamber for receiving particulate-laden liquid. The chamber may be cylindrical. The cylindrical chamber may have a diameter ranging from 120mm to 180mm. The cylindrical chamber may have a diameter of about 300mm. The chamber may have an axial length of 80-100 mm.

The volume of the chamber may be between 1-30 litres. For example, the volume of the chamber may be between 20-30 litres. For example the volume of the chamber may be about 1 litre or 2 litres. Much larger volumes (and thus larger axial heights and diameters) may be appropriate for high volume applications e.g. for sewage treatment.

The filter unit may include a motor for rotating the chamber about the axis of rotation. The motor may include a drive shaft or belt operatively coupled between the motor and the chamber.

In some embodiments, the chamber comprises a particle dispense opening for dispensing particulate matter from within the chamber. The axial centre of the particle dispense opening may be axially aligned with the central longitudinal axis of the chamber.

The particle dispense opening may be selectively openable to dispense particulate matter out of the chamber.

The particle dispense opening may be an opening in the lower end wall. The filter unit has a use configuration (for filtering liquid) where the chamber is rotatable about the axis of rotation such that, in use it collects particulate matter against the collection wall (with the rotatable/slidable member(s) in a closed configuration and the drain hole(s) blocked).

The filter unit has a draining/dewatering configuration where any excess residual liquid remaining in the chamber following operating the filter unit in the use configuration may be drained from the chamber. Draining the residual liquid from the chamber may concentrate the particulate matter to a paste/slurry. In this configuration, the rotatable/slidable member(s) is/are in an open configuration with the drain hole(s) at least partly e.g. fully unblocked.

The filter unit may be configured to be operated in a particle dispense configuration where the filter chamber is static and where the particulate matter collected in the chamber (e.g. on the collection wall) may be extracted or ejected from the chamber via the particle dispense opening.

The filter unit may move from the use (filtering) configuration to the draining/dewatering configuration without stopping rotating. The filter unit may be configured to rotate at the same speed in the use and draining configurations.

According to a second aspect, there is provided a washing apparatus for washing textile items, the apparatus comprising: a main housing in which a washing drum is rotatably mounted, the washing drum including side walls comprising one or more apertures configured to discharge liquid from the washing drum; a collector located downstream of the washing drum and configured to collect liquid discharged from the washing drum; a filter unit according to the first aspect; and a flow pathway between the collector and the inlet of the filter unit.

The outlet of the filter unit may be fluidly connected to the washing drum so that water is recirculated back to the washing drum. This allows filtration of the washing water during the washing cycle i.e. water from the washing drum can be passed to the inlet of the filter unit during the washing cycle and then returned to the washing drum via the outlet. As a result, the washing water used during the washing cycle remains cleaner and better able to ensure thorough washing of the textiles within the washing drum. The outlet of the filter unit may be fluidly connected to a drain.

The outlet of the filter unit also or alternatively may be connected to a storage reservoir for re-use in a subsequent wash cycle. For example, rinse water from a first wash cycle can be stored and used as the wash water in a second wash cycle. In this way the washing machine water consumption can be reduced by up to 60%.

For example, the outlet of the filter unit may be selectively fluidly connectable to the washing drum or storage reservoir so as to be selectively fluidly connected to the drum/reservoir during a washing process. The filter unit (e.g. the drain holes) may be fluidly connectable (e.g. selectively fluidly connectable) to a drain or drum or reservoir during a dewatering process. The apparatus may be a washing machine. The filter unit can be used to clean water during the wash water during the wash cycle to improve wash performance.

According to a third aspect, there is provided a method of filtering particulate matter from particulateladen liquid in an apparatus, including the filter unit according to the first aspect, the method comprising: introducing particulate-laden liquid into the chamber via the inlet; and rotating the chamber about the axis of rotation at a speed configured to move the liquid in a radial direction from the inlet to the peripheral particle collection wall and axially along the peripheral particle collection wall.

Rotating the chamber about the axis of rotation may include operating the motor to rotate the chamber.

The method may include rotating the chamber at a first speed configured to generate centrifugal forces in the rotating liquid that are orders of magnitude greater than the gravitational forces acting on the liquid.

The centrifugal forces being orders of magnitude greater than gravitational forces, it will be apparent to the skilled person that the filter unit may work effectively as described in any orientation, i.e. upside down, horizontally or any point in between.

The rotational speed may be chosen such that the centrifugal force is sufficient to capture a desired percentage of particulate matter against the peripheral particle collection wall (i.e. the collection wall) without the use of any form of barrier filter (e.g. a mesh).

The rotational speed may be between 1000 - 20000 rpm, e.g. between 10,000 and 20,000 rpm. These high speed may be especially suitable for smaller filter units whilst slower speeds, e.g. between 4000 and 6000 rpm may be more suitable for larger filter units.

The method may include rotating the chamber such that the centrifugal force generated in the liquid is 100,000 ms ² or about 10,000 G.

The method may include providing an inlet conduit as described above for the first aspect, rotating the inlet conduit about the axis of rotation in the same direction and/or at the same rotational speed as the chamber.

The method may include providing an outlet as described above for the first aspect and rotating the chamber at the first speed such that particulate matter in the liquid may be collected against the collection wall and filtered liquid may exit the outlet.

The filter unit may have a flow rate of between 0.5 litres/min to 20 litres/min. For example, the filter unit may have a flow rate of about 10 litres/min. In some embodiments, the filter unit may have a flow rate of 15-20 litres/min. Embodiments with significantly higher flow rates are also envisioned.

The above features may relate to the filter unit being operated in the use configuration. Once all the available liquid has been filtered, liquid is no longer introduced into the inlet.

Any excess liquid remaining in the chamber may be ejected from the filter chamber via the drain hole(s). Accordingly, the method may include providing drain holes(s) as described above for the first aspect, moving the rotatable/slidable member(s) to their open configuration and rotating the chamber (e.g. at the same speed as during the use configuration) to drain the chamber of excess residual liquid.

Moving the rotatable/slidable member(s) to their open configuration may comprise using the actuator to contact or create drag on the rotatable/slidable member(s).

The method may comprise rotating the filter chamber as the rotatable/slidable members are moved to their open configuration such that there is no interruption in the rotation of the filter chamber during the transition from the use (filtering) configuration to the draining/dewatering configuration.

Once the excess residual liquid has been ejected from the chamber, the chamber may stop rotating. As the chamber stops rotating, the slurry/paste of particulate matter collected on the collection wall may be allowed to fall (under gravity) toward the lower end wall. The method may include providing a particle dispense opening in the lower end wall as described above for the first aspect such that, as the chamber stops rotating, the particulate matter may be extracted via the particle dispense opening.

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

Summary of the Figures

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

Figure 1 is a schematic cross-sectional drawing of a filter unit to which the present invention may be applied;

Figure 2 is a schematic cross-sectional drawing of another filter unit to which the present invention may be applied;

Figure 3 is a schematic cross-sectional drawing of a further filter unit to which the present invention may be applied;

Figure 4 is a cross-sectional view of a portion of filter unit according to a first embodiment;

Figure 5a is a plan view of the actuating element overlying the rotatable member in the closed (blocking) configuration in the first embodiment;

Figure 5b is a plan view of the actuating element overlying the rotatable member in the open (aligned) configuration in the first embodiment;

Figure 5c is a side view of the actuating element and rotatable member in the rest configuration;

Figure 6 is a cross-sectional view of a portion of the filter unit according to a second embodiment;

Figure 7 is a plan view of the rotatable member of the second embodiment;

Figures 8a and 8b show enlarged view of the biasing elements of the second embodiment; Figure 9 is a cross-sectional view of a portion of the filter unit in a third embodiment;

Figures 10a and 10b are cross-sectional views of a portion of the filter unit in a fourth embodiment;

Figure 11 is a plan view of the annular rotatable member of the fourth embodiment; and

Figure 12 is a plan view of the top axial wall of a fifth embodiment.

Detailed Description

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.

Figure 1 shows a schematic drawing of a filter unit 10 to which the present invention may be applied.

The filter unit 10 includes a cylindrical chamber 12 defined by an upper axial end wall (upper end wall) 14, an opposing lower axial end wall (lower end wall) 16 and a peripheral particle collection wall (collection wall) 18. The upper and lower end walls are spaced by and connected by the collection wall 18. The filter unit 10 includes an inlet opening 23 for delivering particulate-laden liquid into the chamber 12. In particular, the inlet includes a conduit 20 which extends axially through the upper end wall 14 and into the chamber 12. The inlet opening 23 is an axial open end of the conduit 20.

The inlet opening 23 is towards the lower end wall 16. The inlet conduit 20 includes a length that is greater than 80% of the axial length of the chamber 12 such that the axial spacing between the inlet opening 23 and the lower end wall 16 is smaller than the axial spacing between the inlet opening 23 and the upper end wall 14.

The filter unit 10 includes an outlet 24 at the upper end wall 14 for discharging filtered liquid from the chamber 12. In this embodiment, the outlet 24 is an annular opening which circumscribes the inlet conduit 20.

The chamber 12 is rotatable about an axis of rotation 30 which in this embodiment is the central longitudinal axis of the chamber 12. The central longitudinal axis of the inlet conduit 20 and the axial centre of the annular outlet 24 are coaxial with the axis of rotation 30. The filter unit 10 includes a motor 34 for rotating the chamber 12 about the axis of rotation 30.

The flow path of the liquid from the inlet 23 to the outlet 24, as indicated by the arrows 22, includes a radial component from the inlet 23 to the collection wall 18 and an axially upwards component along the collection wall 18. The inlet 23 being towards the lower end wall 16 results in the radial component of the flow path being directly adjacent and parallel to the lower end wall 16. In particular, the inside surface 25 of the lower end wall 16 forms a solid guide surface which guides the liquid from the inlet 23 to the collection wall 18.

Turning to Figure 2 and 3, these show embodiments of filter unit 10 to which the present invention can be applied including a flange 50, in particular a lower flange. The flange 50 extends radially outwardly from the axial open end 23 of the conduit. The radial spacing (i.e. the transverse annular spacing) between the outer edge of the flange 50 and the collection wall 18 is smaller than the radial spacing between the central longitudinal axis of the inlet conduit 20 and the outer edge of the flange (i.e. the outer edge of the flange is closerto the collection wall 18 than the central longitudinal axis of the inlet conduit 20). This advantageously ensures that the majority of the liquid introduced into the chamber is diverted radially outwards towards the collection wall 18 of the chamber 12 where it will be subject to higher centrifugal forces. The axial component of the liquid along the collection wall 18 is therefore closer to and preferably directly adjacent the collection wall 18 (i.e. the axial component of the flow path is directly adjacent to the outer edge of the chamber 12). In this embodiment, the lower surface 52 of the flange 50 forms a guide surface. The inside surface 25 of the lower end wall 16 and the lower surface 52 of the flange 50 both provide solid guide surfaces to guide the liquid from the inlet 23 to the collection wall 18.

In the embodiment of Figure 2, the outlet is an annular opening 24 centred on the axis of rotation 30. The radial spacing from the axis of rotation 30 to the annular opening 24 is less than the radial spacing from the annular opening 24 to the collection wall 18 (i.e. the annular opening 24 is closer to the axis of rotation 30 than to the collection wall 18).

In other examples, the embodiments shown in Figure 1 to 3 include an upper (outlet) flange extending from the conduit proximal and parallel to the upper axial end wall.

For example, Figure 4 shows an upper portion of a filter unit 100 within a chamber housing 101 , the chamber housing having an upper axial end wall 102. The inlet conduit 200 comprises an upper flange 500 which extends radially proximal and parallel the upper axial end wall 140. The upper flange extends radially past the annular outlet 240 and past drain holes 300a, 300b provided in the upper axial end wall 140.

The two drain holes 300a, 300b are diametrically opposed across the central longitudinal axis of the chamber 120. The drain holes 300a, 300b are equally radially spaced from the central longitudinal axis of the chamber 120. The radial spacing between the central longitudinal axis of the chamber and the drain holes 300a, 300b is larger than the radial spacing between the drain holes 300a, 300b and the particlecollection wall 180. The outlet 240 is interposed between the drain holes 300a, 300b and the central longitudinal axis of the chamber 120.

The drain holes 300a, 300b are tapered from an inner surface to an outer surface of the upper end wall 140 i.e. the transverse cross-sectional diameter of the drain holes 300a, 300b increases towards the outer surface.

The drain holes 300a, 300b each include a rotary valve 400a, 400b that has a rotatable member 401 a, 401 b that is moveable (rotatable) between a closed configuration in which the respective drain hole 300a, 300b is obscured by the rotatable member 401 a, 401 b and an open configuration in which the respective drain hole 300a, 300b is fully unobscured to allow liquid to drain out of the chamber.

The rotatable members 401 a, 401 b have a respective aperture 402a (only one visible) that is rotatable into and out of alignment with the respective drain hole 300a, 300b. Thus in the closed configuration (shown for the valve on the right hand side of Figure 4 and in Figure 5a), the aperture 402a is un-aligned with the drain hole 300a but in the open configuration (shown for the valve on the left hand side of Figure 4 and in Figure 5b), the aperture 402a is fully aligned with the drain hole 300a. In practice, both valves will be in the same configuration.

The aperture 402a has dimensions matching those of the drain hole 300a i.e. matching the diameter of the drain hole 300a at the outer surface 140b of the end wall 140 on which the drain hole 300a is provided.

The rotatable members 401 a, 401 b which each comprise circular disc are rotatably mounted on the outer surface of the upper end wall 140 by a respective mounting pin 403a, 403b. The axis of rotation of the rotatable members 401 a, 401 b are parallel to the central longitudinal axis of the chamber 120.

The filter unit 100 further comprises an actuator 500 for effecting rotation of the rotatable member 401 a, 401 b to move the rotatable members 401 a, 401 b between their open and closed configurations. The actuator 500 is configured to interact with the rotatable member 401 a, 401 b of the rotary valves 400a, 400b through direct contact between the actuator 500 and the rotatable members 401 a, 401 b.

The actuator 500 comprises a handle portion 501 external to the chamber housing 101 and mounted on an outer surface of the upper axial end wall 102 of the chamber housing 101. An actuating element 502 is provided internal to the chamber housing 101 and a connecter portion 505 extends through the chamber housing 101 through the upper axial end wall 102 of the chamber housing 101 to connect the handle portion 501 and actuating element 502.

The actuating element 502 is radially movable by a sliding movement into contact with the rotatable members 401 a, 401 b using the handle portion 501 .

The actuating element 502 comprises two downwardly depending radially spaced tabs 503a, 503b. Each rotatable members comprises two bosses 404a/a’, 404b/b’ upstanding from the surface of the rotatable member 401 a, 401 b. This is best seen in Figures 5a-5c which show plan views (Figs 5a and 5b) and a side view (Fig 5c) of the actuating element overlying the rotatable member. The tabs 503a, 503b protrude and the bosses 404a/a’, 404b/b’ upstand sufficiently that there is a common plane perpendicular to the central longitudinal axis of the chamber 120 through which both the actuating element tabs 503a, 503b and rotatable member bosses 404a/a’, 404b/b’ pass.

The actuating element 502 has a rest configuration (seen in Figure 5c) in which the tabs 503a, 503b rest either side of the bosses 404a/a’, 404b/b’ on the rotatable members 401 a, 401 b.

To effect rotation of the rotatable members 401 a, 401 b to close the rotary valves 400a, 400b (so that the filter unit can be used to filter liquid), the handle portion 501 of the actuator 500 is used to slide the actuating element 502 so that a first of the tabs 503a is in the path of a first of the bosses 404a/a’ on the rotatable members 401 a, 401 b as the rotary valves 400a, 400b rotate with the upper axial wall 102 (i.e. as the chamber 120 rotates). The circumferential contact between the first tab 503a and the first boss 404a/a’ in its path rotates the rotatable member 401 a, 401 b on its mounting pin 403a, 403b by knocking the first boss 404a/a’ out of the path of the first tab 503a. As each rotatable member 401 a, 401 b rotates, the apertures 402a in the rotatable members 401 a, 401 b are moved out of alignment with the drain holes 300a, 300b so that liquid cannot exit the drain holes 300a, 300b. To effect rotation of the rotatable members 401 a, 401 b to open the rotary valves 400a, 400b (so that the filter unit can be drained), the handle portion 501 of the actuator 500 is used to slide the actuating element 502 so that a second of the tabs 503b is in the path of the second of the bosses 404b/b’ on the rotatable members 401 a, 401 b as the rotary valves 400a, 400b rotate with the upper axial wall 102. The circumferential contact between the second tab 503b and the second boss 404b/b’ in its path rotates the rotatable member 401 a, 401 b on its mounting pin 403a, 403b by knocking the second boss 404b/b’ out of the path of the second tab 503b. As each rotatable member 401 a, 401 b rotates, the apertures 402a in the rotatable members 401 a, 401 b are moved into alignment with the drain holes 300a, 300b so that liquid can exit the drain holes 300a, 300b.

Turning now to Figures 6-8, a second embodiment with a single annular rotatable member 401 ’ is shown.

Figure 6 shows a cross-sectional view of an upper portion of the second embodiment. The left- and righthand sides of Figure 6 show different operating configurations. Figure 7 shows a top plan view. Figures 8a and 8b show an enlarged view of the biasing elements 408.

It can be seen that the annular rotatable member 401 ’ circumscribes the inlet conduit 20’ and the outlet 24’ which is a discontinuous annular outlet formed in the upper axial end wall 14’ of the filter chamber 12’.

The annular rotatable member 40T has a series of apertures 402’, one for each drain hole 300’. The apertures 402’ are equally spaced in the circumferential direction around the annular rotatable member 401 ’. In Figure 7, the apertures 402’ are seen out of alignment with the drain holes 300’ (shown in dotted lines). This is the closed configuration of the rotatable member 401 ’ for use in the filtering configuration.

The annular rotatable member 40T is mounted on the upper surface of the upper axial end wall 14’ using six mounting pins 403’ extending through the annulus 40T within a respective circumferentially-extending slot 409. In this way, the annular rotatable member 401 ’ can rotate by moving relative to the mounting pins 403’ in the slots 409.

The mounting pins 403’ are each connected to the axial end of a respective biasing member 408 comprising a resilient spring. Each biasing element extends circumferentially within a respective channel 409 in the rotatable member 401 ’. The other end of each biasing element 408 is connected to the rotatable member 401 ’. The biasing elements 408 bias the rotatable member 401 ’ into the blocking configuration with the drain holes 300’ blocked. The blocking configuration can be seen in Figure 8a.

The filter unit further comprises an actuator 500’ (see in Figure 6) configured to apply a frictional force to the rotatable member 40T.

A handle portion 50T external to the chamber housing 101 ’ is mounted on an outer surface of the upper axial end wall of the chamber housing 101 ’ with an actuating element 502’ internal to the chamber housing 101 ’.

The actuating element 502’ is axially movable (from the position shown in the right-hand side of Figure 6) by depression of the handle portion 50T against the resilient bias of a resilient member 600 into contact with the rotatable member 401 (as shown in the left hand side of Figure 6). Note that in practice, only one actuator is needed and the left and right sides of Figure 6 shows the two different operating configurations, holes 300’ open (on left-hand side) and closed (on right-hand side).

In the filtering configuration, the annular rotatable member 401 ’ will be rotating with the upper axial end wall 14’ of the filter chamber 12 in its blocking configuration with the drain holes 300’ closed. The right hand drain hole is shown blocked in Figure 6.

The frictional contact between the actuating element 502’ and the surface of the rotatable member 40T creates drag that acts against the biasing elements 408 to pull the rotatable member 40T against the chamber rotation which causes rotation of the rotatable member 40T relative to the upper axial end wall 14’ so as to rotate the rotatable memberto its open (unblocking) configuration. This compresses the biasing elements 408 and causes the mounting pins 403’ to move within their channels 409 as seen in Figure 8b. The left hand drain hole is shown unblocked in Figure 6. In practice, both drain holes will be in the same configuration.

This transition to the unblocking configuration can be achieved without ceasing rotation of the chamber 12’ and thus allows transition to the draining configuration (once flow of particulate-laden liquid into the inlet conduit 20’ has ceased) without interruption of the filter rotation and thus without dislodgement of the collected debris from the collection wall 18’.

Turning now to Figure 9, a third embodiment with a single annular rotatable member 401 ” is shown. Figure 9 shows a cross-sectional view of an upper portion of the third embodiment. In this embodiment, an electromagnetic actuator 602 is configured to apply an electromagnetic force to the rotatable member 401 ”. The electromagnet is axially fixed relative to the rotatable member. A power supply 601 is external to the chamber housing 10T and is configured to supply an electrical current to a wire coil 603 wound around a ferrous core. The ferrous core comprises two radially spaced extensions 604a, 604b which extend from the ferrous core through the chamber housing. The electrical current supplied to the wire coil 603 magnetises the ferrous core and the extensions 604a, 604b and generates a magnetic field between the extensions 604a, 604b above the rotatable member 401 ’.

The radial spacing between the extensions 604a, 604b is occupied by an upstanding conductive protrusion 605 which may be an annular protrusion.

As the rotatable member 401 ” rotates, the conductive protrusion 605 moves relative to the magnetic field and eddy currents are induced in the axial protrusion 605 by the magnetic field. Each eddy current produces an additional magnetic field that is naturally configured to oppose the magnetic field that induced it. The opposing magnetic fields exert a drag force between the magnetised extensions 604a, 604b and the conductive protrusion 605. The drag force acts against the biasing elements (not shown) to pull the rotatable member 401 ” against the chamber rotation which causes rotation of the rotatable member 401 ” relative to the upper axial end wall 14’ so as to rotate the rotatable member to its open (unblocking) configuration.

The drag force disappears when the power supply is switched off such that the extensions 604a, 604b are demagnetized and the magnetic field ceases. As a result, the rotatable member401 ” returns to the blocking configuration under the force of the biasing elements (not shown). The transition to the unblocking (open) configuration to allow draining of the chamber can be achieved without stopping rotation of the chamber 12’ by switching on the electrical supply to the electromagnetic actuator 602.

Turning now to Figures 10a, 10b and Figure 11 a fourth embodiment with a single annular rotatable member 401 ”’ is shown. Figures 10a and 10b show a cross-sectional view of an upper portion of the fourth embodiment in two different configurations. In this embodiment, a permanent magnet actuator 700 is actuatable to apply an electromagnetic force to the rotatable member 401 ’” (see Figure 10b) using a permanent magnet 702 as the actuating element. A handle portion 701 external to the chamber housing 101 ’ is mounted on an outer surface of the upper axial end wall 102 of the chamber housing 101 ’ with the permanent magnet 702 internal to the chamber housing 10T. A connecter portion 705 extends through the chamber housing 10T to connect the handle portion 701 to the permanent magnet 702. The permanent magnet 702 produces a constant magnetic field. Unlike the electromagnet in the third embodiment, the magnetic field produced by the permanent magnet actuator 700 in this embodiment is not switched on or off using an electrical supply. Instead, the permanent magnet 702 is axially movable (from the position shown in Figure 10a) by depression of the handle portion 701 against the bias of a biasing element 704. Depressing the handle portion 701 moves the magnetic field closer to the rotatable member 40T” (as shown in Figure 10b). Alternatively, the permanent magnet 702 is axially movable (from the position shown in Figure 10a) by supplying an electrical current to a solenoid (not shown in Figures 10a or 10b) coupled to the permanent magnet which moves the permanent magnet and therefore the magnetic field closer to the rotatable member 401 ’”.

The annular rotating member 40T” (shown in Figure 11) is formed of metal and therefore conductive. When the permanent magnet is depressed as the rotatable member 401 ’” rotates, the movement of the conductive rotatable member 40T” relative to the magnetic field causes induction of eddy currents in the rotatable member 401 ’” by the magnetic field. Each eddy current produces a further magnetic field that is naturally configured to oppose the magnetic field that induced it. The opposing magnetic fields exert a drag force between the permanent magnet 702 and the conductive surface 706. The drag force acts against biasing elements 708 (see Figure 11) to pull the rotatable member 40T” against the chamber rotation which causes rotation of the rotatable member 401 ’” relative to the upper axial end wall 14” so as to rotate the rotatable member to its open (unblocking) configuration.

Figure 1 1 shows a top plan view of the single annular rotatable member 401 ’”, which is used in the fourth embodiment as shown in Figures 10a and 10b. In other embodiments (not shown) the rotatable member 401 ’” is used in the second or third embodiments.

In Figure 1 1 , the apertures 402” are seen out of alignment with the drain holes 300” (shown in dotted lines). This is the closed configuration of the rotatable member 401 ’” for use in the filtering configuration. In this embodiment, the rotatable member has six radial protrusions that each move within a respective circumferential channel 712 provided in the upper axial end wall 14” of the chamber.

Three of the radial protrusions 710a are each connected to the axial end of a respective biasing element 708 comprising a resilient spring. Each biasing element 708 extends circumferentially within the corresponding channel 712a in the upper axial end wall 14”. The other end of each biasing element 708 is connected to the upper axial end wall 14”. In this way, the annular rotatable member 40T” can rotate by moving relative to the upper axial end wall 14” in the circumferential channels. The biasing elements 708 bias the rotatable member 401 ’” into the blocking configuration with the drain holes 300’ blocked.

The other three of the radial protrusions 710b are not connected to any biasing element and are received within shorter circumferential channels 712b thus allowing them to act as stop elements to limit the extent of rotation of the rotatable member 401 ”’ (e.g. through an angle of around 10 degrees) by abutment of the radial protrusion against an end surface of the channels.

According to another embodiment (not shown) biasing elements may be omitted from the single annular rotatable member 40T, 401 ” 40T”. The transition between the unblocking configuration and the blocking configuration occurs instead when the direction of rotation of the filter chamber and annular rotatable member 40T, 401 ” 40T” is reversed.

A further embodiment with two slidable elements is shown in Figure 12.

There are two elongated conductive (metal) sliders 800a, 800b each having an elongate axis aligned with a sliding axis of the respective slider 800a, 800b. The sliding axes are perpendicular to the central axis of the chamber. The sliders 800a, 800b and sliding axes are spaced laterally/radially from the central axis of the chamber i.e. the axes do not transect the central axis.

The sliders 800a, 800b are mounted within a respective slot 801 a, 801 b on the outer surface of the circular upper axial end wall 14’”. The slots 801 a, 801 b are elongated and each have an elongate axis coincident with the sliding axis of the respective slider 800a, 800b. The elongate slots 801 a, 801 b have an elongate length greater than an elongate length of the sliders 800a, 800b so that the sliders 800a, 800b can slide within the slots 801 a, 801 b.

The slots 801 a, 801 b extend partly along a portion of a chord of the circular upper end wall 14’”. The two slots 801 a, 801 b are parallel to each other and diametrically opposed.

Each slider 800a, 800b has a respective aperture 802a, 802b extending therethrough in a direction perpendicular to the sliding axes.

Each slider 800a, 800b is connected to a first axial end 803a, 803b of the respective slot 801 a, 801 b by a respective resilient spring biasing member 804a, 804b.

The drain holes 300a, 300b are also provided within the slots 801 a, 801 b. The biasing members 804a, 804b bias the sliders 800a, 800b towards the second axial end 805a, 805b of the respective slot 801a, 801 b such that the apertures 802a, 802b of the sliders 800a, 800b are out of alignment with the drain holes 300a, 300b i.e. the drain holes 300a, 300b are closed. This is exemplified in the slider 800a shown at the bottom portion of Figure 12.

A magnetic actuator (not shown but as described for Figure 10a and 10b) is used to effect sliding of the sliders 800a, 800b from the closed position to an open position where the drain holes 300a, 300b are open. This is exemplified in the slider 800b shown in the top portion of Figure 12. The magnetic actuator is actuatable to apply an electromagnetic force to the sliders 800a, 800b using a permanent magnet as the actuating element. The permanent magnet produces a constant magnetic field and is axially movable by depression of a handle portion (not shown) against the bias of a biasing element (not shown). Depressing the handle portion moves the magnetic field closer to the sliders 800a, 800b. Alternatively, the permanent magnet is axially movable by supplying an electrical current to a solenoid (not shown) coupled to the permanent magnet which moves the permanent magnet and therefore the magnetic field closer to the sliders 800a, 800b.

The sliders 800a, 800b are formed of metal and therefore conductive. When the permanent magnet is depressed as the upper axial end wall 14”’ rotates with the chamber, the movement of the conductive sliders 800a, 800b relative to the magnetic field causes induction of eddy currents in the sliders 800a, 800b by the magnetic field. Each eddy current produces a further magnetic field that is naturally configured to oppose the magnetic field that induced it. The opposing magnetic fields exert a drag force between the permanent magnet and the conductive sliders 800a, 800b. The drag force acts against biasing members 804a, 804b to pull the sliders 800a, 800b against the chamber rotation which causes sliding of the sliders 800a, 800b within their slots 801 a, 801 b in the upper axial end wall 14”’ so as to slide the sliders 800a, 800b to their open (unblocking) configuration with their apertures 802a, 802b aligned with the drain holes 300a, 300b.

The Figure 12 embodiment could alternatively use the frictional actuator shown in Figure 6 or the electromagnetic actuator of Figure 9.

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.

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.

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.

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

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. 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%.