Dirty water tank

Abstract

There is provided a dirty water tank of a surface cleaning system. The dirty water tank comprises: an inlet; a filter for removing debris from water received through the inlet, the filter thereby separating the tank into a water-receiving portion below the filter and a debris-receiving portion above the filter; and a UV light source positioned to illuminate water in the water-receiving portion and debris in the debris-receiving portion with UV radiation.

Description

[0001] 1 P005036-W001

[0002] DIRTY WATER TANK

[0003] BACKGROUND

[0004] Surface cleaning systems, such as floor cleaning systems, may include a clean water tank for storing water to be used to clean the surface, and a dirty water tank for storing water after it has been used to clean the surface.

[0005] The water stored in the dirty water tank may be mixed with debris, such as hair, food, and dust.

[0006] SUMMARY

[0007] According to the present disclosure, there is provided a dirty water tank of a surface cleaning system, the dirty water tank comprising: an inlet; a filter for removing debris from water received through the inlet, the filter thereby separating the tank into a waterreceiving portion below the filter and a debris-receiving portion above the filter; and a UV light source positioned to illuminate water in the water-receiving portion and debris in the debris-receiving portion with UV radiation.

[0008] In this way, both the water in the tank and the debris caught on the filter may be disinfected / sanitised by the UV radiation, and the overall hygiene of the dirty water tank may be improved.

[0009] Optional features will now be set out. These may be applicable singly or in any combination unless clearly impermissible or expressly avoided.

[0010] It will be appreciated that “above” and “below” may be understood to mean “above” and “below” during a normal use and / or position of the dirty water tank. “Above” may be understood to mean on a side or edge closer to the inlet, and “below” may be understood to mean on a side or edge further from the inlet, typically closer to the floor or other surface upon which the dirty water tank is located.

[0011] The surface cleaning system may correspond to a floor cleaning system. The surface cleaning system may comprise a wet surface cleaner (e.g., a wet floor cleaner) and / or a docking station coupleable to the wet surface cleaner. The dirty water tank may be a component of the wet surface cleaner, or the docking station. For example, when the dirty water tank is a component of the docking station, the docking station may be coupleable to 2 P005036-W001 a wet surface cleaner such that a dirty water outlet of the wet surface cleaner is fluidly connected to the inlet of the dirty water tank.

[0012] In some examples, the dirty water tank may have, or may define a tank axis. For example, the tank axis may be a longitudinal and / or central axis of the dirty water tank. As used herein, a “tank axis position” may mean a tank axis coordinate (e.g., a coordinate defined in relation to its position along the tank axis). The tank axis position may not necessarily lie on the tank axis itself.

[0013] The water-receiving portion and the debris-receiving portion may be separated along the tank axis. For example, the filter may be located at a tank axis position P, the debrisreceiving portion may be located at one or more tank axis positions, each of which may be above P, and the water-receiving portion may be located at one or more tank axis positions, each of which may be below P.

[0014] In some examples, the UV light source may extend from a tank axis position above the filter (or from a first tank axis position above a tank axis position P at which the filter is located and / or through which the filter passes) to a tank axis position below the filter (or to a second tank axis position below a tank axis position P at which the filter is located and / or through which the filter passes).

[0015] In this way, a UV light source may illuminate both water in the water-receiving portion and debris in the debris-receiving portion with UV radiation, and the hygiene of the tank may be improved. This in turn reduces unwanted odours that can have an undesirable impact upon user satisfaction.

[0016] In some examples, the UV light source (e.g., the longitudinal axis of the UV light source) may extend parallel to the tank axis, or the UV light source (e.g., the longitudinal axis of the UV light source) may lie along the tank axis.

[0017] In other examples, the UV light source may extend transversely to the tank axis.

[0018] In some examples, the UV light source may extend from the debris-receiving portion to / into the water-receiving portion. In some examples, the UV light source may extend from the debris-receiving portion, through the filter (e.g., through a receiving aperture in the filter) and into the water-receiving portion. For example, the UV light source may extend through a centre of the filter. 3 P005036-W001

[0019] In this way, improved disinfection / sanitisation of the debris and / or the water may be achieved.

[0020] In some examples, the UV light source may be coupled to a wall of the tank. For example, the UV light source may be coupled to the top wall of the tank, the base wall of the tank, or to a side wall of the tank.

[0021] It will be appreciated that the top wall of the tank may be understood to mean the wall defining the top of the tank in normal use and / or position of the tank. In normal position and / or use of the tank, water in the tank may flow in a direction away from the top wall of the tank under the influence of gravity. The inlet may extend through the top wall of the tank, and / or the top wall of the tank may define the inlet. The base wall of the tank may be understood to mean the wall defining the base of the tank in normal use and / or position of the tank. In normal position and / or use of the tank, water in the tank may move in a direction towards the base wall of the tank under the influence of gravity. A side wall of the tank may be understood to mean a wall defining a (lateral) side of the tank in normal use. The side wall may extend from the top wall to the base wall. As an example, a cylindrical dirty water tank may comprise a single side wall, which may extend (e.g., circumferentially) around the tank axis.

[0022] In some examples, where a distance (e.g., the shortest distance) between the top wall and the base wall of the tank is L, the length of the UV light source may be 0.25 L or more, or 0.5 L or more, for example 0.75 L or more.

[0023] In this way, the disinfection / sanitisation by the UV light source may be improved, and the overall hygiene of the tank may be improved.

[0024] In some examples, when the UV light source is coupled to a side wall of the tank, the UV light source may be less prone to damage, and the water tank may be more robust.

[0025] In some examples, the UV light source may be removably coupled to the wall of the tank.

[0026] In this way, the UV light source, which may have a shorter lifespan than one or more other components of the water tank, may be replaceable.

[0027] In some examples, the UV light source may be coupled to an interior surface of the wall.

[0028] In this way, improved disinfection / sanitisation by the UV radiation may be achieved. 4 P005036-W001

[0029] In some examples, the UV light source may be coupled to an exterior surface of the wall.

[0030] In this way, the UV light source may be easier to maintain (e.g., keep clean) and / or to replace.

[0031] It will be appreciated that “interior” and “exterior” may be understood to mean, respectively, within the debris-receiving portion and / or water-receiving portion, and outside the debris-receiving portion and / or water-receiving portion. An interior surface of a wall may face towards the debris-receiving portion and / or water-receiving portion. An exterior surface of a wall may face away from the debris-receiving portion and / or waterreceiving portion.

[0032] In some examples, the UV light source may comprise a UV-C light source. The UV light source may emit UV radiation with a wavelength of 100 nm or more, or 240 nm or more, and / or 280 nm or less, or 270 nm or less. The UV light source may emit UV radiation with a wavelength of approximately 255 nm.

[0033] In some examples the UV light source may be embedded within a UV-transmissible material (e.g., a UV-C transmissible material), for example quartz glass, polytetrafluoroethylene (PFTE), a (specialised) Acrylic, a (specialised) polycarbonate, or UVLON™. The UV transmissible material may be coupled to the wall of the tank. That is to say, the UV light source may be coupled to the wall of the tank via the UV transmissible material.

[0034] In this way, the UV light source may be less prone to damage, and the water tank may be more robust.

[0035] In some examples, the UV light source may comprise a fluorescent lamp, such as a halogen lamp. In some examples, the UV light source may comprise one or more LEDs, which may be aligned along a light source axis. When the UV light source comprises a plurality of LEDs, the longitudinal axis of the UV light source may correspond to the light source axis along which the one or more LEDs are aligned.

[0036] In some examples, one or more of the walls of the tank (e.g., one or more of the side walls, the base wall and / or the top wall) may be formed of a UV-blocking material (i.e., a material which prevents UV passing therethrough), such as metal or a (standard) polycarbonate. 5 P005036-W001

[0037] In this way, UV radiation may be inhibited from escaping from the dirty water tank.

[0038] It may be the case that for improved hygiene of the tank, the water level within the waterreceiving portion should be kept below the filter. In this way, the debris removed by the filter may be kept separate from the water.

[0039] In some examples, where a distance (e.g., the shortest distance) between the inlet and the base of the tank (or between the top wall and the base wall of the tank) is L, a distance (e.g., the shortest distance) between the inlet and the filter (or between the top wall and the filter) may be 0.5 L or less, or 0.3 L or less, or 0.1 L or less.

[0040] In this way, a capacity of the dirty water tank for storing water may be improved, while debris on the filter may be kept separate from the water.

[0041] In some examples, the filter may comprise a mesh. In some examples, the filter may comprise two layers of filter material (e.g., two layers of mesh). An upper layer of filter material may define more apertures (e.g., through which water may pass) than the lower layer of filter material.

[0042] In this way, the removal of debris by the filter may be improved.

[0043] It will be appreciated that, “upper” and “lower” may be understood to mean “upper” and “lower” during normal use and / or position of the dirty water tank. An “upper” element may be understood to refer to an element closer to and / or facing towards the inlet (or a wall of the tank defining the inlet, or through which the inlet extends), and a “lower” element may be understood to refer to an element further from and / or facing away from the inlet (or a wall of the tank defining the inlet, or through which the inlet extends).

[0044] In some examples, the filter may be coupled to (e.g., an interior surface of) one or more side walls of the tank. In some examples, the filter may extend across the tank (e.g., transversely to the tank axis). For example, the filter may extend across a width / diameter (e.g., an entire width / diameter) of the tank, or across a dimension (e.g., an entire dimension) of the tank transverse to the tank axis. In some examples, the filter may extend (e.g., transversely relative to the tank axis) across only an outer portion of the dirty water tank.

[0045] It will be appreciated that “inner portion / side” may be understood to mean the portion / side closer / closest to a centre / central axis (e.g., the tank axis) of the tank, and “outer 6 P005036-W001 portion / side” may be understood to mean the portion / side further / furthest from the centre / central axis (e.g., the tank axis) of the dirty water tank.

[0046] A cross-sectional shape of the filter taken transverse to the tank axis may be circular or annular.

[0047] In some examples, the filter may be rotatable. For example, the filter may be rotatable around the tank axis.

[0048] By rotating the filter, the debris on the filter may be more evenly spread across the filter (i.e., across the upper surface of the filter). Additionally, or alternatively, when the UV light source is coupled to a side wall of the tank, more of the debris may be brought into closer proximity to the UV light source. In this way, it may be possible for the UV light source to better disinfect / sanitise the debris. Additionally, or alternatively, rotating the filter may facilitate water entering the water-receiving portion, as different portions of the filter are positioned under / face the inlet and may be less prone to blockage by debris.

[0049] In some examples, the filter may extend (e.g., circumferentially) around the UV light source. In such examples, the filter may be rotatable around the UV light source.

[0050] In some examples, the filter may comprise a carriage, which may correspond to a peripheral portion of the filter, and / or which may extend around a filtering portion of the filter (the filtering portion for removing debris from the water). The filtering portion may comprise a mesh, two layers of filter material, a primary filter portion and an overflow portion, and / or a debris spreader support and a filter material, as discussed above. The carriage may be for rotatably coupling the filter to one or more side walls of the dirty water tank.

[0051] The dirty water tank may comprise a support fixedly coupled to one or more side walls of the tank (e.g., to an interior surface of a respective one or more side walls of the tank). The filter (e.g., the carriage) may interface with and / or be rotatable on the support (e.g., on an upper surface of the support). The support may extend (e.g., circumferentially) around the tank axis.

[0052] In some examples, the support may comprise a bearing and / or a bushing, which may interface with the filter (e.g., with the carriage).

[0053] In this way, rotation of the filter on the support may be facilitated. 7 P005036-W001

[0054] In some examples, the filter may be rotatable (e.g., on the support) via a motor. The dirty water tank may comprise a motor for rotating the filter. For example, the motor may be (e.g., fixedly) coupled to a side wall of the tank, and / or to the support (e.g., the motor may be coupled to an upper surface of the support). The motor may comprise a rotatable driver (e.g., a gear), which may engage with the filter (e.g., the carriage), for example such that rotating the driver may cause the filter to rotate (e.g., around the tank axis). For example, the rotatable driver may comprise a toothed portion (e.g., a gear). The filter (e.g., the carriage) may comprise a toothed portion (e.g., a gear), complementary in shape to, and engaged with the toothed portion of the rotatable driver. It may be said that the motor comprises a driver gear, and the filter (e.g., the carriage) comprises a driven gear, engaged with the driver gear.

[0055] In some examples, the toothed portion of the filter, or the gear of the filter, may extend circumferentially around the tank axis.

[0056] In some examples, the driver may engage with a lower surface of the filter (e.g., a lower surface of the carriage). In such examples, the lower surface of the filter (e.g., the lower surface of the carriage) may comprise the toothed portion. In other examples, the driver may engage with a side face of the filter (e.g., an outer side face of the filter, which may oppose a side wall of the tank or may face away from a centre of the tank / a central tank axis, or an inner side face of the filter, which may face towards a centre of the tank / a central tank axis). In such examples, the side face of the filter (e.g., the side face of the carriage) may comprise the toothed portion.

[0057] In some examples, the dirty water tank may be coupleable to a power source (e.g., a battery or the mains) for transmitting power to the UV light source, and / or to the motor.

[0058] In some examples, the dirty water tank may further comprise a debris spreader located in the debris-receiving portion. The debris spreader may be moveable with respect to the filter along a filter surface (e.g., along the upper surface of the filter). For example, the filter and / or the debris spreader may be rotatable around the tank axis. For example, the debris spreader may be rotatable around the UV light source.

[0059] Due to such a debris spreader, the debris on the filter may be more evenly spread across the filter surface. In this way, it may be possible for the UV light source to better 8 P005036-W001 disinfect / sanitise the debris. Additionally, or alternatively, water may more readily enter the water-receiving portion, as the filter may be less prone to blockage by debris.

[0060] When the debris spreader is rotatable around the tank axis, the debris spreader may be inhibited from blocking water as the water passes from the inlet to the filter.

[0061] It will be appreciated that the debris spreader may contact the filter surface (e.g., the upper surface), or the debris spreader may be positioned a small distance (e.g., 1 cm or less, 0.5 cm or less, or 0.1 cm or less) above the filter surface.

[0062] In some examples, the debris spreader may be (e.g., fixedly) coupled to a wall of the tank. For example, the debris spreader may be (e.g., fixedly) coupled to (e.g., an interior surface of) the top wall of the tank. In some examples, the debris spreader may be integral with the top wall of the tank.

[0063] It may be useful to inhibit the debris spreader from blocking water as the water passes from the inlet to the filter.

[0064] In some examples, the debris spreader may cover only an inner portion of the filter, or the debris spreader may be moveable with respect to the filter across only an inner portion of the filter. The debris spreader may not cover the outer portion of the filter, and / or (at least a segment of) the outer portion of the filter may be exposed (e.g., to the inlet). In this way, (at least a segment of) the outer portion of the filter may be exposed (e.g., to the inlet), and / or water may pass from the inlet into the water-receiving portion via the outer portion of the debris-receiving portion / filter.

[0065] In some examples the dirty water tank may further comprise an overflow block on the surface (e.g., the upper surface) of the filter. The overflow block may be positioned further from the central axis / tank axis than the inlet. The overflow block may extend (e.g., circumferentially) around the tank axis. The overflow block may split the filter into a primary filter portion on a first side (e.g., an inner side) of the overflow block (e.g., on a side closer to the central axis / tank axis) and an overflow portion on a second side (e.g., an outer side) of the overflow block (e.g., on a side further from the central axis / tank axis). The debris spreader may cover only the primary filter portion of the filter, or the debris spreader may be moveable with respect to the filter across only the primary filter portion of the filter. The debris spreader may not cover the overflow portion of the filter, and / or (at least a segment of) the overflow portion of the filter may be exposed (e.g., to the inlet). 9 P005036-W001

[0066] In this way, if the primary filter portion of the filter is blocked with debris, water may overflow to and pass through the overflow portion of the filter.

[0067] In some examples, the filter may comprise a debris spreader support and a filter material. The debris spreader support may be formed of a solid material, which may be impenetrable to water. The filter material may enable water to pass through and may remove debris from the water as it passes through the filter material. The filter material may be peripheral to the debris spreader support. The debris spreader may cover only the debris spreader support of the filter, or the debris spreader may be moveable with respect to the filter across only the debris spreader support. The debris spreader may not cover the filter material, and / or (at least a segment of) the filter material may be exposed (e.g., to the inlet).

[0068] In this way, the debris spreader may be prevented from causing the filter to be blocked with debris.

[0069] In some examples, a surface (e.g., the upper surface or the lower surface) of the debris spreader may be sloped (downwards) towards the water-receiving portion (e.g., in a direction away from or towards the centre / central axis / tank axis of the tank).

[0070] In this way, the debris spreader may be inhibited from blocking water as the water passes from the inlet to the filter.

[0071] In some examples, the inlet may be located off-centre. For example, the inlet may not be aligned with a central axis (e.g., the tank axis) of the tank.

[0072] In this way, the passing of water from the inlet to the filter may be facilitated.

[0073] In some examples, the dirty water tank may comprise an inlet pipe defining the inlet. The inlet pipe may extend through a wall of the tank (e.g., the top wall of the tank). The inlet pipe may protrude from an exterior surface of the wall (e.g., the top wall) and / or from an interior surface of the wall.

[0074] In this way, delivery of water into the dirty water tank may be facilitated.

[0075] In some examples, the inlet may also correspond to an outlet for emptying water out of the tank. 10 P005036-W001

[0076] In some examples, the dirty water tank may further comprise an agitator to generate movement of water within the water-receiving portion. For example, the agitator may be located within the water-receiving portion.

[0077] In this way, improved disinfection / sanitisation of the water may be achieved. For example, an intensity / strength of UV radiation decreases with increasing distance from the UV light source. Moving the water within the water-receiving portion may enable more of the water to come into close proximity of the UV light source, resulting in improved disinfection / sanitisation of the water.

[0078] In some examples, the agitator may comprise a stirrer or a stir bar. In some examples, the agitator may comprise a magnetic stir bar rotatable, by a rotating magnetic field, to stir water located within the water-receiving portion. For example, the magnetic stir bar (e.g., a longitudinal axis of the magnetic stir bar) may be rotatable around the tank axis.

[0079] In this way, there may be less tangling of debris (e.g., hair) around the agitator, because the magnetic stir bar may not require an axle or bearing. Additionally, or alternatively, sealing and / or manufacture of the tank may be facilitated because the magnetic stir bar may not require direct coupling to a power source.

[0080] It will be appreciated that the magnetic stir bar may be formed of / may comprise a magnetic and / or ferrous material. The magnetic stir bar may comprise a permanent magnet.

[0081] According to a second aspect of the disclosure, there is provided a docking station comprising the dirty water tank according to the first aspect.

[0082] The docking station may be coupleable to a wet surface cleaner (e.g., a wet floor cleaner) such that a dirty water outlet of the wet surface cleaner is fluidly connected to the inlet of the dirty water tank (when the docking station is coupled to the wet surface cleaner).

[0083] For example, the wet surface cleaner may be operable to empty dirty water into the dirty water tank.

[0084] According to a third aspect of the disclosure, there is provided a wet surface cleaner (e.g., a wet floor cleaner) comprising the dirty water tank according to the first aspect.

[0085] According to a fourth aspect of the disclosure, there is provided a dirty water tank of a surface cleaning system, the dirty water tank comprising: an inlet; a water-receiving portion for holding water received through the inlet; a disinfector operable to 11 P005036-W001 disinfect / sanitise and / or sterilise water within the water-receiving portion; and a magnetic stir bar rotatable, by a rotating magnetic field, to stir water within the water-receiving portion.

[0086] The magnetic stir bar may enable improved disinfection / sanitisation of the water by the disinfector, for example, because more water within the water-receiving portion may come into close proximity to the disinfector. Further, by using the magnetic stir bar, there may be less tangling of debris (e.g., hair), because the magnetic stir bar may not require an axle or bearing. Additionally, or alternatively, the sealing and / or manufacture of the tank may be facilitated because the magnetic stir bar may not require direct coupling to a power source.

[0087] Optional features will now be set out. These may be applicable singly or in any combination unless clearly impermissible or expressly avoided.

[0088] It will be appreciated that the magnetic stir bar may be rotatable by a rotating magnetic field generated by a driver. For example, the driver may comprise a driver magnet coupled to a motor, and the motor may be operable to rotate the driver magnet.

[0089] It will further be appreciated that the magnetic stir bar may be formed of a magnetic and / or ferrous material. The magnetic stir bar may comprise a permanent magnet.

[0090] The water-receiving portion may be (at least partially) defined by the one or more sidewalls of the tank and the base wall of the tank.

[0091] In some examples, the dirty water tank may have, or may define a tank axis. For example, the tank axis may be a longitudinal and / or central axis of the dirty water tank. The magnetic stir bar (e.g., a longitudinal axis of the magnetic stir bar) may be rotatable around the tank axis.

[0092] In some examples, where a width / diameter / dimension transverse to the tank axis of the dirty water tank is W, a length of the magnetic stir bar may be 0.75 W or less, 0.5 W or less, 0.3 W or less, or 0.25 W or less.

[0093] In some examples, where a width / diameter / dimension transverse to the tank axis of the dirty water tank is W, a length of the magnetic stir bar may be 0.1 W or more, or 0.2 W or more, or 0.5 W or more.

[0094] In this way, the magnetic stir bar may cause greater agitation of the water for a given RPM of the magnetic stir bar. 12 P005036-W001

[0095] In some examples, the dirty water tank may comprise a restraint, which may be coupled to a wall of the tank (e.g., the base wall or one or more side walls of the tank). The restraint may restrict movement of the magnetic stir bar within the water-receiving portion.

[0096] In this way, the magnetic stir bar may be restrained within a required region or at a required location, and / or the magnetic stir bar may be prevented from escaping from the tank, when the tank is emptied, for example.

[0097] In some examples, the restraint may form (or may at least partially define) an enclosure and the magnetic stir bar may be located within the enclosure. The enclosure may be at least partially defined by the base wall of the tank, and / or by one or more side walls of the tank. The base wall of the tank may be configured to interface with (or face towards, e.g., have an exterior surface facing towards) the driver operable to generate the rotating magnetic field. As an example, the restraint may comprise a cage. The cage may be coupled to the base wall of the tank. The restraint may comprise a mesh. The restraint (e.g., the mesh) may extend across a diameter / width / dimension transverse to the tank axis of the dirty water tank and may be coupled to one or more side walls of the tank.

[0098] In this way, there may be less tangling of debris (e.g., hair), because the magnetic stir bar may not require an axle or bearing to constrain it in a required region.

[0099] In some examples, where a distance (e.g., the shortest distance) between the top wall and the base wall of the tank is L, a distance (e.g., the shortest distance) between the restraint (e.g., an upper surface of the restraint) and the base wall may be 0.25 L or less, or 0.1 L or less, or 0.05 L or less.

[0100] In this way, the magnetic stir bar may be more precisely restrained.

[0101] In some examples, the restraint may comprise an axle and a bearing, wherein the axle and bearing rotatably couple the magnetic stir bar to the wall of the tank (e.g., the base wall). For example, the bearing may be (e.g., directly) fixedly coupled to the wall of the tank, the axle may be (e.g., directly) fixedly coupled to the magnetic stir bar, and the axle may be (e.g., directly) rotatably coupled to the bearing.

[0102] In this way, the magnetic stir bar may be better constrained at a required location.

[0103] In some examples, the dirty water tank may comprise an outlet for emptying water from the water-receiving portion. The outlet may extend through a wall of the tank (e.g., the top 13 P005036-W001 wall of the tank). For example, the inlet may correspond to the outlet (e.g., the same passage through the wall of the tank may form the inlet and the outlet).

[0104] In some examples, the wall of the tank through which the outlet extends may further define (e.g., on an interior surface of the wall of the tank) a depression for catching the magnetic stir bar when water is emptied from the water-receiving portion via the outlet. For example, the depression may have a complementary / similar shape to that of the magnetic stir bar. The depression may have a size similar to / of the order of the size of the magnetic stir bar. For example, when the length of the magnetic bar is L, the depth and / or width of the depression may be at least 0.25 L, at least 0.5 L, at least 0.75 L, or at least L.

[0105] In this way, the magnetic stir bar may be prevented from escaping from the tank when the tank is emptied.

[0106] In some examples, the disinfector may be located within the water-receiving portion.

[0107] In this way, improved disinfection / sanitisation of the water may be achieved.

[0108] In some examples, the disinfector may be coupled to a wall of the tank. For example, the disinfector may be removably coupled to the wall of the tank.

[0109] In this way, the disinfector, which may have a shorter lifespan than one or more other components of the water tank, may be replaceable.

[0110] It will be appreciated that in some examples the disinfector may be a steriliser.

[0111] In some examples, the disinfector may comprise a UV light source (e.g., positioned) to transmit UV radiation into the water-receiving portion.

[0112] In some examples, the dirty water tank may further comprise a filter for removing debris from water received through the inlet, the filter thereby separating the tank into a waterreceiving portion below the filter and a debris-receiving portion above the filter. The water-receiving portion may be defined by the one or more sidewalls of the tank, the base wall of the tank and the filter, for example. The debris-receiving portion may be defined by the one or more sidewalls of the tank, the top wall of the tank and the filter, for example. The water-receiving portion and the debris-receiving portion may be separated along the tank axis. The UV light source may be positioned to illuminate water in the waterreceiving portion and debris in the debris-receiving portion with UV radiation. 14 P005036-W001

[0113] In this way, both the water in the tank and the debris caught on the filter may be disinfected / sanitised by the UV radiation, and the overall hygiene of the dirty water tank may be improved.

[0114] In some examples, the filter may be rotatable. For example, the filter may be rotatable around the tank axis.

[0115] By rotating the filter, the debris on the filter may be more evenly spread across the filter (i.e., across the upper surface of the filter).

[0116] It will be appreciated that the features set out with reference to the first aspect may be equally included in the fourth aspect, unless clearly impermissible, and vice versa. For example, the dirty water tank according to the first aspect may comprise the restraint described with reference to the fourth aspect.

[0117] It will be appreciated that the definitions set out with reference to the first aspect may be equally applicable to the fourth aspect, unless clearly impermissible, and vice versa. As an example, definitions of “upper” and “lower” set out with reference to the first aspect may be equally applicable to the fourth aspect.

[0118] According to a fifth aspect of the disclosure, there is provided a water disinfecting system of a surface cleaning system, the water disinfecting system comprising a dirty water tank according to the fourth aspect, and a driver operable to generate a rotating magnetic field to rotate the magnetic stir bar. For example, the driver may comprise a driver magnet (e.g., directly) coupled to a motor, and the motor may be operable to rotate the driver magnet.

[0119] According to a sixth aspect of the disclosure, there is provided a docking station comprising the dirty water tank according to the fourth aspect.

[0120] The docking station may be coupleable to a wet surface cleaner (e.g., a wet floor cleaner) such that a dirty water outlet of the wet surface cleaner is fluidly connected to the inlet of the dirty water tank (when the docking station is coupled to the wet surface cleaner).

[0121] For example, the wet surface cleaner may be operable to empty dirty water into the dirty water tank.

[0122] According to a seventh aspect of the disclosure, there is provided a wet surface cleaner (e.g., a wet floor cleaner) comprising the dirty water tank according to the fourth aspect. 15 P005036-W001

[0123] BRIEF DESCRIPTION OF THE DRAWINGS

[0124] Figure 1 shows a cross-sectional side view of a dirty water tank.

[0125] Figure 2 shows a cross-sectional top view of a filter.

[0126] Figures 3 A-E show cross-sectional side views of different dirty water tanks with respective UV light sources in different positions.

[0127] Figures 4A-D show cross-sectional side views of different dirty water tanks with respective UV light sources in different positions.

[0128] Figure 5 shows a cross-sectional side view of a dirty water tank.

[0129] Figure 6 shows a cross-sectional top views of a dirty water tank at different time points.

[0130] Figures 7A-7C show cross-sectional side views of different dirty water tanks with respective motors in different positions.

[0131] Figure 8 shows a cross-sectional side view of a dirty water tank.

[0132] Figures 9A-9B show cross-sectional side views of dirty water tanks.

[0133] Figure 10 shows a cross-sectional side view of a dirty water tank.

[0134] Figure 11 shows a cross-sectional top view of a dirty water tank.

[0135] Figure 12 shows a cross-sectional side view of a dirty water tank.

[0136] Figure 13 shows a cross-sectional side view of a water disinfecting system.

[0137] Figures 14A-14C shows cross-sectional side views of different dirty water tanks with different respective restraints.

[0138] Figure 15 shows a cross-sectional side view of a dirty water tank.

[0139] DETAILED DESCRIPTION

[0140] Figure 1 shows a cross-sectional side view of an example of a dirty water tank 100 according to the present disclosure. The dirty water tank 100 may be a component of a wet surface cleaner (e.g., a floor cleaner), or a docking station for coupling to a wet surface cleaner.

[0141] The dirty water tank 100 is roughly cylindrical, having a top wall 102, a base wall 104, and a circumferential side wall 106 extending from the top wall 102 to the base wall 104. A tank axis is defined, which is the central longitudinal axis of the dirty water tank 100. The dirty water tank 100 comprises an inlet pipe 108 protruding from and extending through the top wall 102 and a UV light source 110 coupled to the top wall 102 and extending 16 P005036-W001 centrally through the tank along the tank axis. The dirty water tank 100 further comprises a filter 112, in the form of a mesh, coupled to the side wall 106 and extending across the tank (transversely to the tank axis) and circumferentially around the UV light source 110. The filter 112 is positioned closer to the top wall 102 of the tank than the base wall 104, such that the distance between the top wall 102 and the filter 112 is approximately a quarter of the distance between the top wall 102 and the base wall 104. The filter 112 splits the dirty water tank 100 into a debris-receiving portion 116 above the filter 112 and a waterreceiving portion 114 below the filter 112, and the UV light source 110 extends through the debris-receiving portion 116 and into the water-receiving portion 114.

[0142] The dirty water tank 100 shown in Figure 1 is holding water 118 in the water-receiving portion 114, and debris 119 on the filter 112.

[0143] When water is received through the inlet 108, it passes through the filter 112, which removes debris from the water, and into the water-receiving portion 114. The UV light source 110 can then illuminate water in the water-receiving portion 114 and debris in the debris-receiving portion 116 with UV radiation to disinfect / sanitise both the water 118 in the water-receiving portion 114 and the debris in the debris-receiving portion 116.

[0144] Figure 2 shows a top cross-sectional view of the filter 112 used in the Figure 1 dirty water tank 100. As shown in Figure 2, the cross-section of the filter 112 taken transverse to the tank axis is annular in shape. The filter 112 defines a receiving aperture through which the UV light source 110 is received.

[0145] Although the UV light source 110 in the example shown in Figure 1 extends centrally through the tank along the tank axis, in other examples, the UV light source may be located at other positions in the dirty water tank.

[0146] The dirty water tanks described below share several features in common with that of the dirty water tank 100 shown in Figure 1. For conciseness, these features may not be described again. Further, in the below-described figures, the inlet of the respective dirty water tank may not be shown for clarity of the respective figure.

[0147] Figures 3A-3E show cross-sectional side views of different dirty water tanks 300a-e with respective UV light sources 310a-e at different positions. For clarity, the filters and inlets are not shown in the Figure 3A-3E dirty water tanks 300a-e. Figure 3A shows a UV light source 310a coupled to the top wall 302a and extending centrally through the tank along 17 P005036-W001 the tank axis. Figure 3B shows a UV light source 310b coupled to the base wall 304b and extending centrally through the tank along the tank axis. Figure 3C shows a UV light source 310c coupled to the top wall 302c and extending transversely relative to the tank axis along the top wall 302c. Figure 3D shows a UV light source 310d coupled to the base wall 304d and extending transversely relative to the tank axis along the base wall 304d. Figure 3E shows a UV light source 310e coupled to the side wall 306e of the tank and extending parallel to the tank axis along the side wall 306e.

[0148] The UV light sources 3 lOa-e shown in Figures 3 A-3E are fluorescent lamps.

[0149] Figures 4A-4D show cross-sectional side views of different dirty water tanks 400a-d with respective UV light sources 410a-e at different locations within the dirty water tank. The UV light sources 410a-e shown in Figures 4A-4D each comprise a plurality of LEDs aligned along a longitudinal axis of the respective UV light source. Figure 4A shows a UV light source 410a coupled to the top wall 402a which has a longitudinal axis extending transversely to the tank axis along the top wall 402a. Figure 4B shows a UV light source 410b coupled to the base wall 404b which has a longitudinal axis extending transversely to the tank axis along the base wall 404b. Figure 4C shows a UV light source 410c coupled to an exterior surface of the side wall 406c of the tank which has a longitudinal axis extending parallel to the tank axis along the side wall 406c. Figure 4D shows a UV light source 410d coupled to an interior surface of the side wall 406d of the tank which has a longitudinal axis extending parallel to the tank axis along the side wall 406d.

[0150] Turning now to the filter, in some examples, the filter may be rotatable around the tank axis. Figure 5 shows a cross-sectional side view of an example of a dirty water tank 500 which includes a rotatable filter 512. For clarity, the UV light source is not shown in the Figure 5 dirty water tank 500.

[0151] The dirty water tank 500 shown in Figure 5 comprises a support 520 fixedly extending circumferentially around the tank axis and coupled to the side wall 506, the support 520 holding the filter 512. The support 520 comprises a bearing or a bushing such that the filter 512 can rotate around the tank axis along the surface of the support 520. The filter 512 comprises a peripheral carriage 522 which interfaces with the support 520. The carriage 522 extends around a filtering portion 524 of the filter 512 (the filtering portion 524 being 18 P005036-W001 for removing the debris from the water). As shown in Figure 5, the filtering portion 524 is formed of two layers of mesh.

[0152] Rotation of the filter 512 enables the debris to be more evenly spread across the filter surface. Figure 6 shows a top cross-sectional view of the Figure 5 dirty water tank 500 at progressive time points as the filter 512 rotates clockwise. As shown in Figure 6, because the portion of the filter 512 which is directly under the inlet 508 changes as the filter 512 rotates, the debris can be deposited more evenly across the surface of the filter 512.

[0153] Although not shown in Figure 5, the rotation of the filter 512 may be driven by a motor. Figures 7A-7C show cross-sectional side views of different dirty water tanks 700a-c, with respective motors 726 located at different positions.

[0154] Figure 7A shows a motor 726a fixedly coupled to the exterior surface of the side wall 706a, while Figures 7B and 7C each show a motor 726b / c fixedly coupled to the support 720. Each of the motors 726a-c comprises a driver gear 728a-c which engages with a complementary-shaped toothed portion of the carriage 722 (not visible in the figures), the toothed portion extending circumferentially around the tank axis. In Figure 7A, the outer side face of the carriage 722 (which faces the side wall 706a) comprises the toothed portion, and the driver gear 728a engages with the toothed portion on the outer side face. In Figure 7B, the inner side face of the carriage 722 (which faces towards the tank axis) comprises the toothed portion, and the driver gear 728b engages with the toothed portion on the inner side face. In Figure 7C, the lower surface of the carriage 722 (which faces towards the support 720) comprises the toothed portion, and the driver gear 728c engages with the toothed portion on the lower side face.

[0155] Although the UV light sources are not shown in Figures 7A-7B, the UV light sources may be in any of the positions described with reference to Figures 3A -3E or 4A-44D. For example, the UV light source may extend along the tank axis, and the filter may be rotatable around the UV light source.

[0156] Figures 8 shows a cross-sectional side view of a dirty water tank 800 with a rotatable filter 812, where the dirty water tank 800 comprises a debris spreader 830 in the debris-receiving portion 816 located a small distance above the upper surface of the filter 812. Although not shown in this figure, the debris spreader 830 may be fixedly coupled to the top wall 802 of the dirty water tank 800. 19 P005036-W001

[0157] Therefore, when the filter 812 rotates around the tank axis, the debris spreader 830 spreads the debris across the surface of the filter 812. In other examples, the filter 812 may be fixedly coupled to the side wall 806 of the tank, and the debris spreader 830 may be rotatable around the tank axis.

[0158] Further, the debris spreader 830 shown in Figure 8 has an upper surface sloped downwards towards the water-receiving portion 814 of the tank, which may facilitate water passing to the water-receiving portion 814.

[0159] Figures 9A and 9B show cross-sectional side views of alternative examples of dirty water tanks 900a / b, each with a rotatable filter 912a / b and a debris spreader 930a / b in the debrisreceiving portion 916a / b.

[0160] The filter 912a shown in Figure 9A comprises a solid debris spreader support 932, and a peripheral filter material 934 around the debris spreader support 932. The debris spreader 930a covers only the debris spreader support 932, which may reduce the likelihood of the relative movement between the debris spreader 930a and the filter 912a causing blockage of the filter 912a.

[0161] The dirty water tank 900b shown in Figure 9B comprises an overflow block 936 on the upper surface of the filter 912b and extending around the tank axis. The overflow block 936 splits the filter 912b into a primary filter portion 940 on an inner side of the overflow block and an overflow portion 938 on an outer side of the overflow block. The debris spreader 930b only covers the primary filter portion 940. In this way, if the primary filter portion 940 of the filter 912b is blocked with debris, water may overflow to and pass through the overflow portion 938 of the filter.

[0162] Figure 10 shows a cross-sectional side view of an alternative example of a dirty water tank 1000 with a rotatable filter 1012 and a debris spreader 1030 in the debris-receiving portion 1016.

[0163] The motor 1026 and the filter 1012 are arranged and interact correspondingly to the motor 1026 and filter 1012 described above with reference to Figure 7B.

[0164] The debris spreader 1030 is integral with and extends from the interior surface of top wall 1002. Further, the debris spreader 1030 shown in Figure 10 has a lower surface sloped downwards towards the water-receiving portion 1014 of the tank. 20 P005036-W001

[0165] Figure 11 shows a top cross-sectional view of the Figure 10 dirty water tank 1000, in which the side wall 1006, the debris spreader 1030, the filter 1012 (both the carriage 1022 and the filtering portion 1024) and the inlet 1008 are shown.

[0166] Figure 12 shows an example of a dirty water tank 1200 which includes an agitator 1242, in the form of a magnetic stir bar, in the water-receiving portion 1214. The length of the magnetic stir bar 1242 is smaller than the diameter of the dirty water tank 1200, optionally 1 / 3 of the diameter of the dirty water tank 1200, and the longitudinal axis of the magnetic stir bar 1242 is rotatable around the tank axis to stir water within the water-receiving portion 1214. The magnetic stir 1242 bar is rotatable by a rotating magnetic field.

[0167] Figure 13 shows an example of a disinfecting system comprising a dirty water tank 1300 and a driver 1344. The base wall 1304 of the dirty water tank 1300 interfaces with the driver.

[0168] The dirty water tank 1300 comprises a disinfector in the form of a UV light source 1310 fixedly coupled to the top wall 1302 of the tank and extending centrally through the tank along the tank axis into a water-receiving portion 1314 of the tank. Although not shown in the Figure, the dirty water tank 1300 also includes an inlet for receiving water therethrough. A magnetic stir bar 1342 is located in the water-receiving portion 1314 of the tank. The magnetic stir bar 1342 is rotatable around the tank axis by a rotating magnetic field generated by the driver 1344, to thereby stir the water within the water-receiving portion 1314.

[0169] The driver 1344 comprises a driver magnet 1346 coupled to a motor 1348, and the motor 1348 is operable to rotate the driver magnet 1346.

[0170] Figures 14A-C show examples of dirty water tanks 1400a-c, which each comprise a respective restraint 1450a-c restricting the movement of the magnetic stir bar 1442 within the water-receiving portion 1414. These dirty water tanks 1400a-c share several features in common with that shown of Figure 13, which for conciseness will not be repeated here.

[0171] The restraint 1450a in the example of Figure 14A is in the form of a cage coupled to the base wall 1404a of the tank. The cage 1450a and the base wall 1404a together form an enclosure within which the magnetic stir bar is located. 21 P005036-W001

[0172] The restraint 1450b in the example of Figure 14B is in the form of a mesh which extends across the diameter of the dirty water tank 1400b and is coupled to the interior surface of the side wall 1406b at a position proximate the base wall 1404b. The mesh 1450b and the base wall 1404b together form an enclosure within which the magnetic stir bar 1442 is located.

[0173] The restraint 1450c in the example of Figure 14C comprises an axle 1452 and a bearing 1454 which rotatably couple the magnetic stir bar 1442 to the base wall 1404c of the tank. In more detail, the bearing 1454 is fixedly coupled to the base wall 1404c, the axle 1452, extending from the bearing 1454 to the magnetic stir bar 1442, is fixedly coupled to the magnetic stir bar 1442 and rotatably coupled to the bearing 1454.

[0174] Figure 15 shows an example of a dirty water tank 1500 which comprises a lipped top wall 1502. This dirty water tank 1500 shares several features in common with that shown of Figure 13, which for conciseness will not be repeated here.

[0175] Although not shown in Figure 15, a passage extends through the top wall 1502, which forms both an inlet and an outlet of the tank (for receiving water therethrough and respectively filling or emptying the water-receiving portion 1514).

[0176] The interior surface of the top wall 1502 further defines a depression (or a lip) 1556 for catching the magnetic stir bar when the water is emptied from the water-receiving portion 1514 via the outlet. To this end, as shown in Figure 15, the size of the depression 1556 is of the order of that of the magnetic stir bar.

[0177] Although the dirty water tanks shown in Figures 13 and 14A-C and 15 do not include filters, in some examples these dirty water tanks may include filters, such as those described above with reference to Figures 1 to 12.

Claims

22 P005036-W001CLAIMS1. A dirty water tank of a surface cleaning system, the dirty water tank comprising: an inlet; a filter for removing debris from water received through the inlet, the filter thereby separating the tank into a water-receiving portion below the filter and a debris-receiving portion above the filter; and, a UV light source positioned to illuminate water in the water-receiving portion and debris in the debris-receiving portion with UV radiation.

2. A dirty water tank according to claim 1, wherein the water-receiving portion and the debris-receiving portion are separated along a tank axis, and wherein the UV light source extends from a tank axis position above the filter to a tank axis position below the filter.

3. A dirty water tank according to any of the preceding claims, wherein the water-receiving portion and the debris-receiving portion are separated along a tank axis, and wherein the filter is rotatable around the tank axis.

4. A dirty water tank according to any of the preceding claims further comprising: a debris spreader located in the debris-receiving portion, wherein: the debris spreader is moveable, with respect to the filter, along a filter surface.

5. A dirty water tank according to claim 4, wherein the water-receiving portion and the debris-receiving portion are separated along a tank axis, and wherein the debris spreader is rotatable around the tank axis.

6. A dirty water tank according to claim 4 or claim 5, wherein: the debris spreader is moveable with respect to the filter across only an inner portion of the filter.23 P005036-W0017. A dirty water tank according to claim 5 or claim 6, wherein the debris spreader has an upper surface facing towards a wall of the tank through which the inlet extends, and wherein the upper surface slopes towards the water-receiving portion.

8. A dirty water tank according to any of claims 1 to 7 wherein the UV light source extends along a tank axis which is central.

9. A dirty water tank according to any of claims 1 to 8, wherein: the UV light source extends through a receiving aperture in the filter; and, the UV light source extends into the water-receiving portion.

10. A dirty water tank according to any of claims 1 to 7, wherein: the tank comprises a side wall to which the filter is coupled, the side wall at least partially defining the water-receiving portion; and, the UV light source is coupled to the side wall of the tank.

11. A dirty water tank according to any of the preceding claims, wherein the UV light source comprises a fluorescent lamp or one or more LEDs.

12. A dirty water tank according to any of the preceding claims, further comprising an agitator to generate movement of water within the water-receiving portion.

13. A dirty water tank according to claim 12, wherein the agitator comprises a magnetic stir bar rotatable, by a rotating magnetic field, to stir water located within the waterreceiving portion.

14. A docking station comprising the dirty water tank of any of the preceding claims, wherein the docking station is coupleable to a wet surface cleaner such that a dirty water outlet of the wet surface cleaner is fluidly connected to the inlet of the dirty water tank.

15. A wet surface cleaner comprising the dirty water tank of any of claims 1 to 14.

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