Wet cleaning apparatus comprising pump assembly

Abstract

Provided is a wet cleaning apparatus (100) having a porous cleaning material (104) that includes a front side (108) for contacting a surface to be cleaned (158), and a back side (106) that faces away from the front side. The wet cleaning apparatus further includes a cleaning liquid tank (152) for containing cleaning liquid (154), and a pump assembly. The pump assembly is configured to operate in an underpressure generating mode and in a cleaning liquid wetting mode, e.g. a cleaning liquid wetting mode that is implementable prior to the pump assembly being operated in the underpressure generating mode. When the pump assembly is operating in the underpressure generating mode, a liquid pick-up region (161) of the porous cleaning material is exposed, at the back side, to an underpressure generated by the pump assembly to enable liquid on the surface to be cleaned to be drawn into pores of the porous cleaning material. When the pump assembly is operating in the cleaning liquid wetting mode, cleaning liquid is delivered by the pump assembly from the cleaning liquid tank to the liquid pick-up region, at the back side, to wet the pores of the porous cleaning material with the cleaning liquid.

Description

[0001] 2024PF00045 11.08.2025

[0002] 1

[0003] WET CLEANING APPARATUS COMPRISING PUMP ASSEMBLY

[0004] FIELD OF THE INVENTION

[0005] The invention relates to a wet cleaning apparatus for cleaning a surface.

[0006] The wet cleaning apparatus can be used, for example, for cleaning a floor, an indoor surface, or a window.

[0007] BACKGROUND OF THE INVENTION

[0008] Wet cleaning apparatuses, for example wet mopping devices, are known which remove water from a surface to be cleaned. Wet cleaning apparatuses can alternatively or additionally apply cleaning liquid, e.g. water, to the surface to be cleaned, and then remove the liquid, e.g. with a suitable cloth.

[0009] Some wet cleaning apparatuses have powered pick-up functionality for removing the water from the surface to be cleaned. Wet vacuum cleaners, for instance, may pick up liquid by generating sufficient air speed (e.g. at least 10 m / s) and / or brush power to exert enough shear force on liquid droplets to cause them to enter the device. Typical power consumption values for such vacuum cleaners are relatively high, for example in the order of several hundred watts.

[0010] Certain wet cleaning apparatuses make use of a porous cleaning material that covers dirt inlet(s) in which an underpressure is provided by an underpressure generator, e.g. a pump. When the porous cleaning material is dry, the porous cleaning material may be regarded as being in an “air transport state” in which air is transported through each of the dry pores of the porous cleaning material. A “liquid transport state” corresponds to liquid, e.g. water, being transported through the (wetted) pores of the porous cleaning material. When there is no longer a feed of liquid to the pores, a “fluid block state” may be adopted. The “fluid block state” corresponds to the state at which the surface tension of the (residual) liquid retained in the wetted pores of the porous cleaning material prevents fluid transport through the pores. In the latter state, a surface or barrier is created at the boundary between air and liquid, e.g. water. This barrier can assist to maintain the underpressure between the porous cleaning material and the underpressure generator. 2024PF00045 11.08.2025

[0011] 2

[0012] The working principle of this porous cleaning material-comprising wet cleaning apparatus may depend on air ingress into the pores being blocked by liquid-air surfaces (surface tension), which can obviate the need to use a relatively high power pump to compensate for the (unnecessary) ingress of air (noting that such blocked pores can allow for an underpressure build-up inside the wet cleaning apparatus without the need for such a relatively high power pump). Moreover, liquid, e.g. water, needing to be picked up from the surface to be cleaned can remove the liquid-air surface locally, and hence only a modest underpressure may be required in order for the liquid to be drawn into the pores.

[0013] Thus, significantly less energy may be consumed to pick up liquid from the surface to be cleaned compared to, for example, wet vacuum cleaners of the type described above.

[0014] EP4209159A1 provides a wet cleaning apparatus comprising a cleaner head. The cleaner head has at least one dirt inlet, and a porous material comprising a porous material layer sealingly attached to the at least one dirt inlet. The wet cleaning apparatus also comprises an underpressure generator arrangement comprising an underpressure generator. The underpressure generator has an underpressure generator outlet. The underpressure generator is activatable to provide a flow from the at least one dirt inlet to and through the underpressure generator outlet, and deactivatable to cease the flow. The underpressure generator arrangement is configured to restrict the passage of fluid from the underpressure generator outlet towards the at least one dirt inlet at least when the underpressure generator is deactivated. In another aspect, a cleaner head includes a valve assembly configured to restrict backflow towards a porous material layer sealingly attached to dirt inlet(s).

[0015] SUMMARY OF THE INVENTION

[0016] The above-described porous cleaning material-comprising wet cleaning apparatus may, however, have a start-up time. This start-up time is the time required for the liquid pick-up functionality of the wet cleaning apparatus to become fully operational. The start-up time may depend on how quickly the pores of the porous cleaning material can be wetted to enable the underpressure to be generated behind the porous cleaning material. A delay associated with achieving sufficient wetting of the porous cleaning material can detriment usability of the wet cleaning apparatus.

[0017] The invention is defined by the claims.

[0018] According to examples in accordance with an aspect of the invention, there is provided a wet cleaning apparatus comprising: a porous cleaning material comprising a front 2024PF00045 11.08.2025

[0019] 3 side for contacting a surface to be cleaned, and a back side that faces away from the front side; a cleaning liquid tank for containing cleaning liquid; and a pump assembly configured to operate in: an underpressure generating mode in which a liquid pick-up region of the porous cleaning material is exposed, at the back side, to an underpressure generated by the pump assembly to enable liquid on the surface to be cleaned to be drawn into pores of the porous cleaning material, the porous cleaning material being arranged to enable the front side to maintain contact with the surface to be cleaned irrespective of how long the pump assembly is operated in the underpressure generating mode; and a cleaning liquid wetting mode in which cleaning liquid is delivered by the pump assembly from the cleaning liquid tank to the liquid pick-up region, at the back side, to wet the pores of the porous cleaning material with the cleaning liquid.

[0020] As a consequence of operating the pump assembly in the cleaning liquid wetting mode, e.g. prior to operating the pump assembly in the underpressure generating mode, the liquid pick-up functionality of the wet cleaning apparatus can be fully operational, due to efficient wetting of the pores of the porous cleaning material with the cleaning liquid, in significantly less time compared to when no cleaning liquid wetting mode is implemented. This reduction in the start-up time can enhance usability of the wet cleaning apparatus.

[0021] By the front side of the porous cleaning material being able to maintain contact with the surface to be cleaned irrespective of how long the pump assembly is operated in the underpressure generating mode, the wet cleaning apparatus can continue to draw liquid from the surface to be cleaned throughout the pump assembly’s operation in the underpressure generating mode.

[0022] It is noted that the front side can also maintain contact with the surface to be cleaned while the pump assembly is operating in the cleaning liquid wetting mode.

[0023] The surface to be cleaned may become wet relatively quickly following startup when the pump assembly is operated in the cleaning liquid wetting mode, e.g. prior to operating in the underpressure generating mode. This can mean that the user can begin wetting, and thus cleaning, the surface more quickly.

[0024] In some embodiments, the pump assembly is configured to switch automatically from initially operating in the cleaning liquid wetting mode to subsequently operating in the underpressure generating mode. This can alleviate burden on the user, since the user need not himself / herself be required to switch the mode of the pump assembly to the underpressure generating mode following the wetting of the liquid pick-up region with the cleaning liquid. 2024PF00045 11.08.2025

[0025] 4

[0026] In some embodiments, the pump assembly is configured to initially operate in the cleaning liquid wetting mode for a given time period and / or until a given amount of the cleaning liquid has been delivered to the liquid pick-up region, at the back side, and automatically switch from operating in the cleaning liquid wetting mode to operating in the underpressure generating mode subject to the given time period having elapsed and / or the given amount of the cleaning liquid having been delivered to the liquid pick-up region, at the back side.

[0027] Such a given time period, e.g. about 10 seconds, and / or such a given amount of the cleaning liquid can assist to ensure that the porous cleaning material is sufficiently wetted prior to the pump assembly being operated in the underpressure generating mode.

[0028] In some embodiments, the pump assembly is configured to initially operate in the cleaning liquid wetting mode upon activation, e.g. switching on, of the pump assembly. In other words, the cleaning liquid wetting mode may be selected automatically / by default when the pump assembly is activated, e.g. switched on.

[0029] This can provide a relatively quick and convenient way of making the liquid pick-up functionality of the wet cleaning apparatus fully operational, via wetting of the pores of the porous cleaning material, since there may be no delay associated with the user having to select the cleaning liquid wetting mode following activation, e.g. switching on, of the pump assembly.

[0030] In some embodiments, the wet cleaning apparatus comprises a monitoring system configured to determine whether a given time period has elapsed following deactivation, e.g. switching off, of the pump assembly. In such embodiments, the pump assembly may be configured to initially operate in the cleaning liquid wetting mode upon activation, e.g. switching on, of the pump assembly, subject to the monitoring system determining that the given time period has elapsed.

[0031] In such embodiments, if the monitoring system determines that the given time period has not elapsed, the pump assembly may, for example, be configured to initially operate in the underpressure generating mode upon activation, e.g. switching on, of the pump assembly.

[0032] In this way, the cleaning liquid wetting mode need only be initially employed upon activation of the pump assembly if wetting is warranted, e.g. owing to the amount of time, for allowing drying of the porous cleaning material, that has passed since deactivation of the pump assembly. 2024PF00045 11.08.2025

[0033] 5

[0034] Any suitable time period can be used for the given time period, e.g. depending on the drying properties of the porous cleaning material. In some embodiments, the given time period is in the range of 20 to 40 minutes, such as about 30 minutes.

[0035] The monitoring system can be implemented in any suitable manner. In some embodiments, the monitoring system comprises electronics having a timer, with the timercomprising electronics being configured to check whether the given time period has elapsed, for example by determining whether the pump assembly was activated during the given time period, e.g. during the past 30 minutes.

[0036] The pump assembly can be configured in any suitable manner in order to enable operation in the cleaning liquid wetting mode and, e.g. subsequently, in the underpressure generating mode.

[0037] In some embodiments, the pump assembly comprises a pump drivable in a first direction to deliver the cleaning liquid to the liquid pick-up region, at the back side, in the cleaning liquid wetting mode, and drivable in a second direction opposite the first direction to expose the liquid pick-up region, at the back side, to the underpressure in the underpressure generating mode.

[0038] This may provide a relatively simple way of implementing the two modes, since the same pump can be used to pump the cleaning liquid in the cleaning liquid delivery mode and to generate the underpressure in the underpressure generating mode.

[0039] In other embodiments, the pump assembly comprises a first pump for providing the underpressure in the underpressure generating mode, and a second pump, different from the first pump, for delivering the cleaning liquid from the cleaning liquid tank to the liquid pick-up region, at the back side, in the cleaning liquid wetting mode.

[0040] In some embodiments, the pump assembly comprises at least one positive displacement pump, for example at least one positive displacement pump in the form of a peristaltic pump. Such a positive displacement pump, e.g. peristaltic pump, can, for example, be driven in the first direction in the cleaning liquid wetting mode and in the second direction in the underpressure generating mode.

[0041] Such a positive displacement pump can assist to maintain the underpressure after the pump assembly has been deactivated, e.g. switched off, because the pump design inherently restricts backflow from the pump outlet. This, in turn, may alleviate problematic liquid release from the porous cleaning material, for instance following cleaning of the surface to be cleaned and / or during stowing of the wet cleaning apparatus in a storage area after use. 2024PF00045 11.08.2025

[0042] 6

[0043] In some embodiments, the liquid pick-up region, at the back side, is exposed to the underpressure via a conduit fluidly connecting the liquid pick-up region, at the back side, to the pump assembly, when the pump assembly is operating in the underpressure generating mode, and the cleaning liquid is deliverable to the liquid pick-up region, at the back side, via the same conduit when the pump assembly is operating in the cleaning liquid wetting mode. Such a design can be relatively straightforward to manufacture, since it can avoid use of multiple conduits being used to deliver the cleaning liquid to the liquid pick-up region in the cleaning liquid wetting mode and to subject the liquid pick-up region to the underpressure in the underpressure generating mode.

[0044] The wet cleaning apparatus may include a dirty liquid collection tank.

[0045] In such embodiments, the pump assembly may be arranged, when operating in the underpressure generating mode, to draw liquid from the back side of the porous cleaning material to the dirty liquid collection tank.

[0046] In some embodiments, the pump assembly comprises a valve assembly configured to restrict flow of the cleaning liquid from the cleaning liquid tank towards the liquid pick-up region, at the back side, when the pump assembly is operating in the underpressure generating mode. The valve assembly can include, for example, a one-way valve that is closed / closes in response to the direction of flow that provides the underpressure in the underpressure generating mode.

[0047] In this manner, the valve assembly, e.g. the one-way valve thereof, can assist to minimize or prevent the cleaning liquid from interfering with liquid pick-up during operation of the pump assembly in the underpressure generating mode.

[0048] In some embodiments, the valve assembly is configured to restrict flow of the dirty liquid collected in the wet cleaning apparatus, e.g. in a dirty liquid collection tank thereof, towards the liquid pick-up region, at the back side, when the pump assembly is operating in the cleaning liquid wetting mode. The valve assembly can include, for example, a (further) one-way valve that is closed / closes in response to the direction of flow that delivers the cleaning liquid towards the liquid pick-up region, at the back side.

[0049] In this way, the valve assembly, e.g. the (further) one-way valve thereof, can assist to minimize or prevent unwanted flow of dirty liquid back towards the back side of the porous cleaning material during operation of the pump assembly in the cleaning liquid wetting mode.

[0050] In some embodiments, the porous cleaning material comprises a cleaning liquid delivery region, in addition to the liquid pick-up region, with the wet cleaning 2024PF00045 11.08.2025

[0051] 7 apparatus comprising a cleaning liquid delivery system configured to deliver the cleaning liquid from the cleaning liquid tank to the cleaning liquid delivery region.

[0052] This delivery of the cleaning liquid by the cleaning liquid delivery system can, for example, be implemented while the pump assembly is operating in the underpressure generating mode.

[0053] By simultaneously delivering the cleaning liquid towards the surface to be cleaned and picking up liquid from the surface to be cleaned, the wet cleaning apparatus can clean the surface without the surface becoming excessively wet.

[0054] In some embodiments, a flow through the porous cleaning material generated by the pump assembly when operating in the underpressure generating mode is equal to or greater than a flow of the cleaning liquid provided by the cleaning liquid delivery system towards the surface to be cleaned.

[0055] For example, the flow of cleaning liquid may be in the range of 20 to 100 cm3 / minute, and the flow provided by the pump assembly operating in the underpressure generating mode may be in the range of 40 to 2000 cm3 / minute, more preferably 80 to 750 cm3 / minute, even more preferably 100 to 300 cm3 / minute, and most preferably 150 to 300 cm3 / minute.

[0056] In some embodiments, the wet cleaning apparatus includes a cleaning liquid pump for pumping the cleaning liquid from the cleaning liquid tank towards the surface to be cleaned.

[0057] In such embodiments, the cleaning liquid pump can, for example, be provided in addition to the pump assembly, e.g. in addition to the pump included in the pump assembly for providing at least the underpressure generating mode.

[0058] In some embodiments, the porous cleaning material comprises a porous layer and a further porous layer, with at least the liquid pick-up region, at the back side, being provided by the porous layer, and at least part, e.g. the entirety, of the front side being provided by the further porous layer.

[0059] In such embodiments, the further porous layer may, for example, be detachable from the cleaner head.

[0060] Thus, the further porous layer can be detached for cleaning and / or replacement after use.

[0061] In some embodiments, the further porous layer comprises a projections- comprising side, with the project! ons-comprising side comprising projections, e.g. tufts and / or ridges, arranged so that at least some of the projections are contactable with the 2024PF00045 11.08.2025

[0062] 8 surface to be cleaned. Coarse dirt, e.g. sand, may be accommodated in spaces between the projections, thereby alleviating the risk of scratching of the surface to be cleaned. It is also noted that the projections can accommodate unevenness of the surface to be cleaned, noting that individual projections can enter recesses, dislocations etc. in the surface to be cleaned.

[0063] The pump assembly may be configured to, when being operated in the underpressure generating mode, provide a pressure difference between an inside of the wet cleaning apparatus and atmospheric pressure for drawing fluid through the porous cleaning material, with the pressure difference being in a range of 3000 Pa to 13500 Pa, preferably 5000 Pa to 9000 Pa, most preferably 7000 Pa to 9000 Pa.

[0064] Alternatively or additionally, the pump assembly may be configured to generate a flow through the porous cleaning material that is at most 2000 cm3 / minute when the pump assembly is being operated in the underpressure generating mode.

[0065] In some embodiments, the pump assembly is configured, when operating in the underpressure generating mode, to provide the underpressure by providing a flow through the porous cleaning material in the range of 15 to 2000 cm3 / minute, more preferably 80 to 750 cm3 / minute, even more preferably 100 to 300 cm3 / minute, and most preferably 150 to 300 cm3 / minute.

[0066] Such a flow, i.e. flow rate, may capitalize on the underpressure-maintaining capability of the porous cleaning material, and may ensure sufficient liquid pick-up whilst limiting energy consumption.

[0067] More generally, the wet cleaning apparatus may comprise, for example, a wet mopping device, a window cleaner, a sweeper, or a wet vacuum cleaner, such as canistertype, stick type, or upright type wet vacuum cleaner. The wet cleaning apparatus may in some examples comprise a robotic wet vacuum cleaner or a robotic wet mopping device configured to autonomously move the porous cleaning material on the surface to be cleaned, such as the surface of a floor. Particular mention is made of a wet mopping device.

[0068] In a particular non-limiting example, the wet cleaning apparatus is a battery- powered (or battery-powerable) wet cleaning apparatus, such as a battery-powered (or battery-powerable) wet mopping device, in which the pump assembly is powered (or powerable) by a battery electrically connected (or connectable) thereto. Particular mention is made of this example due to the power consumption-reducing effect which can be provided by the porous cleaning material to which the suction of the pump assembly is applied when operating in the underpressure generating mode. 2024PF00045 11.08.2025

[0069] 9

[0070] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

[0071] BRIEF DESCRIPTION OF THE DRAWINGS

[0072] For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0073] FIG. 1 schematically depicts a liquid transport state, intermediate regime and end regime sequence of a porous cleaning material when liquid and suction are applied thereto;

[0074] FIG. 2 schematically depicts a test arrangement for testing the behavior of the porous cleaning material when liquid and suction are applied thereto;

[0075] FIG. 3 provides a graph of underpressure vs time from data acquired using the test arrangement shown in FIG. 2;

[0076] FIG. 4 schematically depicts a wet cleaning apparatus;

[0077] FIGs. 5A and 5B schematically depict another wet cleaning apparatus;

[0078] FIG. 6 schematically depicts a wet cleaning apparatus according to an additional example; and

[0079] FIG. 7 schematically depicts a wet cleaning apparatus according to a further example.

[0080] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0081] The invention will be described with reference to the Figures.

[0082] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0083] Provided is a wet cleaning apparatus having a porous cleaning material that includes a front side for contacting a surface to be cleaned, and a back side that faces away 2024PF00045 11.08.2025

[0084] 10 from the front side. The wet cleaning apparatus further includes a cleaning liquid tank for containing cleaning liquid, and a pump assembly. The pump assembly is configured to operate in an underpressure generating mode and in a cleaning liquid wetting mode, e.g. in a cleaning liquid wetting mode that is implementable prior to the pump assembly being operated in the underpressure generating mode. When the pump assembly is operating in the underpressure generating mode, a liquid pick-up region of the porous cleaning material is exposed, at the back side, to an underpressure generated by the pump assembly to enable liquid on the surface to be cleaned to be drawn into pores of the porous cleaning material. When the pump assembly is operating in the cleaning liquid wetting mode, cleaning liquid is delivered by the pump assembly from the cleaning liquid tank to the liquid pick-up region, at the back side, to wet the pores of the porous cleaning material with the cleaning liquid.

[0085] FIG. 1 schematically depicts a working principle of a wet cleaning apparatus 100 comprising an underpressure generator 102 and a porous cleaning material 104. The underpressure generator 102 may be arranged to apply suction to a back side 106 of the porous cleaning material 104. The front side 108 of the porous cleaning material 104 can, in use, contact the surface to be cleaned (not visible in FIG. 1).

[0086] The wet cleaning apparatus 100 can comprise a cleaner head 110 in which a dirt inlet structure 112 is defined, with the dirt inlet structure 112 being arranged to apply the suction generated by the underpressure generator 102 to a liquid pick-up region 161 of the porous material 104, at the back side 106, of the porous cleaning material 104.

[0087] The liquid pick-up region 161 of the porous cleaning material 104 may, for example, be delimited by sealing attachment of at least part of the porous cleaning material 104 around the dirt inlet structure 112.

[0088] The sealing attachment of the at least part of the porous cleaning material 104 around the dirt inlet structure 112, may assist to maintain an underpressure in the dirt inlet structure 112 with or without the flow being applied by the underpressure generator 102 included in the wet cleaning apparatus 100.

[0089] The sealing attachment can be implemented in any suitable manner, such as by gluing or welding the at least part of the porous cleaning material 104 around the dirt inlet structure 112, for example gluing and / or welding the at least part of the porous cleaning material 104 around one or more tubes or channels that define the dirt inlet structure 112.

[0090] Still referring to FIG. 1, the cleaner head 110 can comprise a support substrate 114. The support substrate 114 may, for example, be regarded as a main body of the cleaner head 110. 2024PF00045 11.08.2025

[0091] 11

[0092] The support substrate 114 may, for instance, be a pliable support substrate 114. Such a pliable support substrate 114 can assist the cleaner head 110 to follow contours on the surface to be cleaned. Alternatively or additionally, the pliability of the pliable support substrate 114 may assist cleaning of the cleaner head 110 after use, for example involving wringing liquid from the cleaner head 110 and / or washing at least part of the cleaner head 110 in the user’s washing machine.

[0093] Such a pliable support substrate 114 may be formed from any suitable pliable material. For example, the pliable material forming the pliable support substrate 114 can comprise a polymeric material and / or elastomeric material.

[0094] Particular mention is made of silicone rubber and ethylene-vinyl acetate, in other words a copolymer of ethylene and vinyl acetate, for the pliable material.

[0095] Other polymeric and / or elastomeric materials, such as a poly diene, e.g. polybutadiene, a thermoplastic elastomer, and so on, can also be contemplated for the pliable material.

[0096] Alternatively or additionally, the pliable material can be less than 50 Shore A, preferably less than 20 Shore A, most preferably less than 10 Shore A.

[0097] In a non-limiting example, the pliable material is 4 Shore A silicone rubber.

[0098] The pliable support substrate 114 can, for instance, be formed from a closed cell foam material, for example an ethylene-vinyl acetate closed cell foam material.

[0099] Such a closed cell foam material may facilitate an efficient (and inexpensive) product! on / assembly process for fabricating the cleaner head 110. Moreover, the closed cellular structure of the closed cell foam material can assist to retain liquid in the dirt inlet structure 112.

[0100] When the cleaner head 110 comprises the support substrate 114, e.g. the pliable support substrate 114, the dirt inlet structure 112 may be recessed into and / or embossed on a bottom surface of the support substrate 114, which bottom surface faces, in use, the surface to be cleaned.

[0101] In the scenario that the dirt inlet structure 112 is recessed into the bottom surface of the support substrate 114, the dirt inlet structure 112 may comprise, e.g. be defined by, a groove defined in and extending across at least part of the bottom surface.

[0102] When the dirt inlet structure 112 is embossed on the bottom surface of the support substrate 114, the dirt inlet structure 112 may comprise, e.g. be defined by, an arrangement of protruding elements protruding from the bottom surface and extending across 2024PF00045 11.08.2025

[0103] 12 at least part of the bottom surface, with path(s) for the dirty liquid being defined between protruding elements of the arrangement of protruding elements.

[0104] As shown in FIG. 1, a dirt conduit 116 can fluidly connect the dirt inlet structure 112 to the underpressure generator 102. At least part of the dirt conduit 116 can be defined, for example, in a connector for connecting the cleaner head 110 to the underpressure generator 102.

[0105] FIG. 1 schematically depicts pores 118 of the porous cleaning material 104. When the porous cleaning material 104 is dry, the porous cleaning material 104 may be regarded as being in an “air transport state” in which air is transported through each of the dry pores 118 of the porous cleaning material 104. A “liquid transport state”, as shown in a) of FIG. 1, corresponds to liquid, e.g. water, being transported through all of the (wetted) pores 118 of the porous cleaning material 104 (but note that the (ample) liquid below the pores is not visible in a)). The end of the “liquid transport state” is shown in b) of FIG. 1, an intermediate regime is shown in c) of FIG. 1, and an end regime is shown in d) of FIG. 1.

[0106] The pores 118, e.g. micropores, may each have a different “breaking pressure.” This is represented in FIG. 1 by the number provided underneath each pore 118. For the sake of simplicity, each number is rounded to a single digit.

[0107] Taking as an illustrative example a porous cleaning material 104 in the form of a cloth made from fibers and yams, which are woven together into a sheet of fabric, the pore sizes present in such a porous cleaning material 104 may be defined between all fibers and yams, so the pore sizes present in the cloth are not fixed to exactly one size, but rather vary statistically. This variation is represented in FIG. 1 via the different numbers under each pore 118.

[0108] At start-up of the underpressure generator 102, e.g. pump, all liquid, e.g. water, is drawn from the surface to be cleaned, and the required pressure is the liquid transport pressure, in this example set at “1”. The underpressure in the dirt inlet structure 112 behind the porous cleaning material 104 is correspondingly “1”.

[0109] In b), the underpressure starts to rise. When all the liquid, e.g. water, has been removed from the surface to be cleaned, all pores 118 may be blocked via the surface tension of the residual liquid therein. In the depicted illustrative example, the underpressure generator 102 is a fixed flow pump, and hence continued operation of the pump may increase the underpressure. At a certain point, the underpressure in the dirt inlet structure 112 may rise to the level, such as “4”, of the breaking pressure of the “weakest” pores 118, and exceeding of the breaking pressure of these pores 118 means that air starts to be transported therethrough. 2024PF00045 11.08.2025

[0110] 13

[0111] Since the pressure in the dirt inlet structure 112 behind the porous cleaning material 104 may already be significant when these first pores 118 “break”, the air transported by these pores 118 at this point may be significant. Step c) in FIG. 1 can thus be regarded as schematically representing an intermediate regime.

[0112] In the intermediate regime, pores 118 may be getting blocked while other pores 118 are still transporting liquid from further regions (further away from the dirt inlet structure 112), hence creating more underpressure close to the dirt inlet structure 112. This can make the underpressure rise relatively slowly until all free liquid is gone. This may all be influenced by the pump rate and, in at least some examples, the properties of the dirt inlet structure 112, together with the flexibility of all elements, deforming when underpressure is applied.

[0113] This process may continue until the air transported is equal to the pump rate in this illustrative example, and the underpressure in the dirt inlet structure 112 behind the porous cleaning material 104 is lower than the breaking pressure of the remaining “unbroken” pores 118 having the lowest breaking pressure. Step d) in FIG. 1 can thus be regarded as schematically representing an end regime.

[0114] FIG. 2 schematically depicts an exemplary test arrangement 120 for testing the breaking pressure characteristics of the porous cleaning material 104. The porous cleaning material 104 is clamped between a clamping member 122 and a base plate 124. The clamping member 122 delimits holes for bolts 126, which bolts 126 are received in threaded holes in the base plate 124. Turning of the bolts 126 in the appropriate direction enables clamping / releasing of the porous cleaning material 104.

[0115] In this specific example, the clamping member 122 is an aluminium ring having a thickness of 10 mm, and the base plate 124 is made of poly (methyl methacrylate) having a thickness of 10 mm. The sample of the porous cleaning material 104 is a circular disk having a diameter of 140 mm. The sample is secured using eight bolts 126.

[0116] The dirt inlet structure 112 in this test arrangement 120 is provided in the form of a coarse mesh with a diameter of 80 mm. The dirt conduit 116 is partly defined by an opening of a transport duct 128 provided in the base plate 124.

[0117] The test arrangement 120 comprises an underpressure generator 102 for generating an underpressure in the dirt inlet structure 112, and a pressure sensor 130, e.g. a pressure gauge, arranged to measure the pressure in the dirt inlet structure 112. 2024PF00045 11.08.2025

[0118] 14

[0119] The pressure sensor 130 in this specific example comprises a pressure gauge in combination with a data acquisition unit (LabQuest® 2) to enable monitoring of the pressure as a function of time.

[0120] The underpressure generator 102 in this specific example is in the form of a peristaltic pump or a syringe pump, e.g. a 250 mL syringe pump. The peristaltic pump can provide a pulsed water flow. The syringe pump was found to permit more precise measurements than the peristaltic pump.

[0121] The test arrangement 120 also comprises a pressure line filter 132 in the form of a chamber arranged to prevent liquid from entering the pressure sensor line 134 connecting the pressure line filter 132 with the pressure sensor 130. Downstream of the pressure line filter 132 and the underpressure generator 102 is a collection reservoir 136 for collecting the liquid pumped through the porous cleaning material 104.

[0122] The testing procedure comprises clamping the sample of the porous cleaning material 104 between the clamping member 122 and the base plate 124, and then setting the underpressure generator 102 to deliver a flow rate of 100 cm3 / minute. The pressure line filter 132 is checked to ensure that it is empty, the pressure gauge of the pressure sensor 130 is zeroed and reconnected before each measurement. 25 cm3of water is then poured onto the sample of the porous cleaning material 104, leaving a layer of water on the porous cleaning material 104 having a depth of approximately 4 mm. A flushing run is then implemented by starting the underpressure generator 102 such that the water is pulled through the sample of the porous cleaning material 104. Following the flushing run, the underpressure generator 102 is stopped and 25 cm3of water is poured onto the sample of the porous cleaning material 104, and a measurement run is implemented by triggering the data acquisition unit to start the data acquisition and starting the underpressure generator 102.

[0123] A typical graph of underpressure vs time from the data acquisition is provided in FIG. 3, together with schematic diagrams of the porous cleaning material 104. Initially, the above-described “liquid transport state” 138 is adopted in which the liquid 140, in this example water, is transported through the (pre-wetted) pore 118. The recorded “transport pressure” in this case corresponds to the pressure difference required to transport the liquid 140 through the porous cleaning material 104 and the dirt inlet structure 112.

[0124] The governing equation describing the “liquid transport state” 138 may be the following Poiseuille equation: 2024PF00045 11.08.2025

[0125] 15 where AP is the pressure difference across the pore 118; r| is the dynamic viscosity of the liquid; L is the length of the pore 118; (|> is the volumetric flow rate; and r is the radius of the pore 118.

[0126] Assuming, for instance, a pore diameter of 20 pm, with the pore 118 extending across a porous cleaning material 104 having a thickness of 0.8 mm, with an estimated volumetric flow rate of about 4.96* 10'14m3 / s per pore 118 (from a typical fluid flow of 100 cm3 / minute), and with qWater being l*10'3Pa s, AP = 10.1 Pa.

[0127] Subsequently to the “liquid transport state” 138, the intermediate regime 142 is adopted in which almost all of the liquid 140 has been removed from the surface of the sample of the porous cleaning material 104, such that most of the pores 118 are in the abovedescribed “fluid block state” in which the surface tension of the (residual) liquid 140 retained in the wetted pore(s) 118 of the porous cleaning material 104 prevents air 144 from being transported through the pore 118. An ever decreasing number of pores 118 may be in the “liquid transport state” in the intermediate regime 142. The “fluid block state” allows a significantly higher underpressure, so during the intermediate regime 142 the underpressure increases relatively rapidly, as shown.

[0128] The governing equation describing the “fluid block state” may be the following Droplet dP equation:

[0129] 2T

[0130] Pi1- P0u= — R where Pi and Po are the inside and outside pressures, and R is the fluid drop radius, as schematically depicted in FIG. 3. T is the surface tension.

[0131] Assuming, for instance, that R is 10 pm for a typical 20 pm diameter pore 118, and Twater is 0.073 N / m, Pi - Po = AP = 14600 Pa.

[0132] The AP of 14600 Pa from the above Droplet dP equation may be increased to 18000 Pa when detergent is added to the water. Whilst water surface tension decreases when detergent is added (TSOapy water is 0.045 N / m.), two surfaces in the bubble over the pore 118 are created: the inside and the outside of the bubble. Thus, the breaking pressure in the case of detergent being added to the water may be approximately double that of a single-layer surface:

[0133] 4T

[0134] Pi1- Pou= — R

[0135] Following the intermediate regime 142, the end regime 146 is adopted in which all free water has been removed from the surface of the porous cleaning material 104, 2024PF00045 11.08.2025

[0136] 16 and all the pores 118 are initially in the “fluid block state”. Since the underpressure generator 102 continues drawing water through the porous cleaning material 104, hence increasing the underpressure, this may cause some of the fluid blocks to break such that air 144 is transported through the respective pores 118 in an “air transport state”. The associated ingress of air may come to an equilibrium in the end regime 146 in which the applied flow results in an underpressure which causes no more fluid blocks to break. The latter corresponds to the “breaking pressure” of the porous cleaning material 104 being investigated.

[0137] The governing equation describing the “air transport state” may be the Poiseuille equation provided above for the “liquid transport state”. Assuming, for instance, a pore diameter of 20 pm, with the pore 118 extending across a porous cleaning material 104 having a thickness of 0.8 mm, with an estimated volumetric flow rate of about 4.96* 10'14m3 / s per pore 118 (from a typical fluid flow of 100 cm3 / minute), and with T|air being 18.1*10'6Pa s, AP = 0.18 Pa.

[0138] Overall, the air transport pressure (e.g. 0.18 Pa) and the water transport pressure (e.g. 10.1 Pa) may both be significantly smaller, e.g. negligible, in comparison to the surface tension-derived pressure difference (e.g. 14600 Pa).

[0139] The porous cleaning material 104 may accordingly be selected to provide a relatively large difference between breaking pressure and water transport pressure. The significant advantage of this is that the porous cleaning material 104 can be “pre-tensioned” by the underpressure generator 102. A wetted porous cleaning material 104, e.g. pick-up pad, can be set to a pressure of, for example, 14600 Pa. When this state is reached, no more power may be needed. Whenever a droplet of liquid, e.g. water, is added to the porous cleaning material 104, the air-liquid surface disappears and suddenly the function of transporting the liquid can be fulfilled at a pressure difference of, for example, 10 Pa.

[0140] Thus, the wet cleaning apparatus 100 can be highly energy-efficient and effective. Liquid, e.g. water, may only be transported at the position where it is fed to the porous cleaning material 104. Once no liquid is provided for transportation, the wet cleaning apparatus 100 can return to its “pre-tensioned” state.

[0141] The pore size, in other words pore diameter, of the pores 118 of the porous cleaning material 104 may be selected in order to balance a relatively high underpressure with a relatively low resistance to transport of liquid through the porous cleaning material 104. 2024PF00045 11.08.2025

[0142] 17

[0143] Whilst the foregoing has focussed on pick-up of liquid from the surface to be cleaned, a key consideration is delivery of cleaning liquid towards the surface to be cleaned. FIG. 4 schematically depicts a wet cleaning apparatus 100 comprising the underpressure generator 102, the porous cleaning material 104, the dirt inlet structure 112, and the dirt conduit 116, as well as a dirty liquid collection tank 148 arranged to receive the dirty liquid 150 from the dirt inlet structure 112. Moreover, the wet cleaning apparatus 100 shown in FIG. 4 comprises a cleaning liquid tank 152 for containing cleaning liquid 154, and a cleaning liquid delivery system configured to deliver the cleaning liquid 154 from the cleaning liquid tank 152 towards the surface to be cleaned 158, for instance by delivering the cleaning liquid 154 to the back side 106 of the porous cleaning material 104 and / or to a cleaning liquid delivery region 160 of the porous cleaning material 104, which cleaning liquid delivery region 160 is provided in addition to the liquid pick-up region 161.

[0144] The cleaning liquid delivery system can, for example, include a cleaning liquid outlet structure 156 for delivering the cleaning liquid 154 towards the surface to be cleaned 158, such as to the back side 106 and / or to the cleaning liquid delivery region 160 of the porous cleaning material 104.

[0145] As shown in FIG. 4, a cleaning liquid pump 162 can transport the cleaning liquid 154 towards the surface to be cleaned 158. Thus, the cleaning liquid pump 162 can pump the cleaning liquid 154 towards the surface to be cleaned 158, while the underpressure generated by the underpressure generator 102 removes liquid from the porous cleaning material 104, e.g. to fill the dirty liquid collection tank 148.

[0146] It is reiterated at this point that the working principle may depend on the pores 118, wetted with liquid, e.g. water, causing air ingress into the pores 118 to be blocked by the liquid-air surfaces (surface tension), which can obviate the need to use a relatively high power pump to compensate for the (unnecessary) ingress of air (noting that such blocked pores 118 can allow for an underpressure build-up inside the wet cleaning apparatus 100 without the need for such a relatively high power pump). Moreover, liquid, e.g. water, needing to be picked up from the surface to be cleaned 158 can remove the liquid-air surface locally, and hence only a modest underpressure may be needed in order for the liquid to be drawn into the pores 118. Thus, the underpressure that has been built up behind the porous cleaning material 104 can be capable of picking up the liquid present on the surface to be cleaned 158.

[0147] However, the start-up time of the wet cleaning apparatus 100 may depend on how quickly the pores 118 can be wetted to enable the necessary underpressure to be 2024PF00045 11.08.2025

[0148] 18 generated. A start-up sequence of the wet cleaning apparatus 100 shown in FIG. 4 may be as follows:

[0149] 1. The wet cleaning apparatus 100 is started by both the underpressure generator 102, e.g. peristaltic pump, and the cleaning liquid pump 162 being activated.

[0150] 2. The cleaning liquid pump 162 can deliver the cleaning liquid 154 to the cleaning liquid delivery region 160 of the porous cleaning material 104, to wet the cleaning liquid delivery region 160. This can take some time, due to the absorbent nature of the cleaning liquid delivery region 160.

[0151] 3. After some time, the cleaning delivery region 160 can be wet enough to wet the surface to be cleaned 158 (see arrow Al in FIG. 4).

[0152] 4. The liquid pick-up region 161 of the porous cleaning material 104 can then be wetted by the cleaning liquid 154 on the surface to be cleaned 158 (see arrow A2 in FIG. 4), at least partly due to movement of the porous cleaning material 104 over the surface to be cleaned 158 by the user.

[0153] 5. The cleaning liquid 154 may then need to saturate the porous cleaning material 104, including the liquid pick-up region 161, before the desired / requisite underpressure can be built-up behind the liquid pick-up region 161, e.g. in the dirt inlet structure 112.

[0154] This whole process can, for example, take about 3 minutes. In more general terms, the start-up time of the wet cleaning apparatus 100 can depend on how quickly all of the pores 118 of the porous cleaning material 104 can be wetted, so as to enable the desired / requisite underpressure to be generated. Hence the user may be inconvenienced with having to wait for such a period in order to make use of a wet cleaning apparatus 100 whose liquid pick-up functionality is fully operational.

[0155] For this reason, and referring now to FIGs. 5A and 5B, the present disclosure contemplates a pump assembly 164 configured to operate in a cleaning liquid wetting mode (see FIG. 5A), e.g. a cleaning liquid wetting mode implementable prior to the pump assembly 164 being operated in an underpressure generating mode (see FIG. 5B).

[0156] In the cleaning liquid wetting mode, the cleaning liquid 154 is delivered by the pump assembly 164 from the cleaning liquid tank 152 to the liquid pick-up region 161, at the back side 106, of the porous cleaning material 104, to wet the pores 118 of the porous cleaning material 104 with the cleaning liquid 154 (see the arrows 165 in FIG. 5 A).

[0157] Thus, the cleaning liquid 154 wets the liquid pick-up region 161 via the back side 106, so as to provide wetting of the liquid pick-up region 161 from the inside of the wet cleaning apparatus 100. 2024PF00045 11.08.2025

[0158] 19

[0159] In the underpressure generating mode, e.g. implemented subsequently to the cleaning liquid wetting mode, the liquid pick-up region 161, at the back side 106, of the porous cleaning material 104 is exposed to an underpressure generated by the pump assembly 164 to enable liquid on the surface to be cleaned 158 to be drawn into pores 118 of the porous cleaning material 104 (see the arrows 166 in FIG. 5B).

[0160] As a consequence of operating the pump assembly 164 in the cleaning liquid wetting mode, e.g. prior to operating the pump assembly 164 in the underpressure generating mode, the liquid pick-up functionality of the wet cleaning apparatus 100 can be fully operational in significantly less time, e.g. after about 15 seconds, compared to when no cleaning liquid wetting mode is implemented (which can be about 3 minutes, as noted above).

[0161] It is noted that the arrangement of the porous cleaning material 104 is shown in FIG. 5B as enabling the front side 108 to maintain contact with the surface to be cleaned 158 irrespective of how long the pump assembly 164 is operated in the underpressure generating mode. Thus, the wet cleaning apparatus 100 can continue to draw liquid from the surface to be cleaned 158 throughout the pump assembly’s 164 operation in the underpressure generating mode.

[0162] The front side 108 can also maintain contact with the surface to be cleaned 158 while the pump assembly 164 is operating in the cleaning liquid wetting mode (see FIG. 5 A). This can enable the surface to be cleaned 158 to become wet relatively quickly following start-up when the pump assembly 164 is operated in the cleaning liquid wetting mode, e.g. prior to operating in the underpressure generating mode. This may, for example, enable the surface to be cleaned 158 to become visibly wet after only about 2 seconds, instead of after about 15 seconds when no cleaning liquid wetting mode is implemented.

[0163] In some embodiments, the pump assembly 164 is configured to switch automatically from initially operating in the cleaning liquid wetting mode to subsequently operating in the underpressure generating mode. This can alleviate burden on the user, since the user need not himself / herself be required to switch the mode of the pump assembly 164 to the underpressure generating mode following the wetting of the liquid pick-up region 161 with the cleaning liquid 154.

[0164] In some embodiments, the pump assembly 164 is configured to initially operate in the cleaning liquid wetting mode for a given time period and / or until a given amount of the cleaning liquid 154 has been delivered to the liquid pick-up region 161, at the back side 106, and automatically switch from operating in the cleaning liquid wetting mode 2024PF00045 11.08.2025

[0165] 20 to operating in the underpressure generating mode subject to the given time period having elapsed and / or the given amount of the cleaning liquid 154 having been delivered to the liquid pick-up region 161, at the back side 106.

[0166] Such a given time period, e.g. about 10 seconds, and / or such a given amount of the cleaning liquid 154 can assist to ensure that the porous cleaning material 104 is sufficiently wetted prior to the pump assembly 164 being operated in the underpressure generating mode.

[0167] In some embodiments, the pump assembly 164 is configured to initially operate in the cleaning liquid wetting mode upon activation, e.g. switching on, of the pump assembly 164. In other words, the cleaning liquid wetting mode may be selected automatically / by default when the pump assembly 164 is activated, e.g. switched on.

[0168] This can provide a relatively quick and convenient way of making the liquid pick-up functionality of the wet cleaning apparatus 100 fully operational, via wetting of the pores 118 of the porous cleaning material 104, since there may be no delay associated with the user having to select the cleaning liquid wetting mode following activation, e.g. switching on, of the pump assembly 164.

[0169] In some embodiments, the wet cleaning apparatus 100 comprises a monitoring system configured to determine whether a given time period has elapsed following deactivation, e.g. switching off, of the pump assembly 164. In such embodiments, the pump assembly 164 may be configured to initially operate in the cleaning liquid wetting mode upon activation, e.g. switching on, of the pump assembly 164, subject to the monitoring system determining that the given time period has elapsed.

[0170] In such embodiments, if the monitoring system determines that the given time period has not elapsed, the pump assembly 164 may, for example, be configured to initially operate in the underpressure generating mode upon activation, e.g. switching on, of the pump assembly 164.

[0171] In this way, the cleaning liquid wetting mode need only be initially employed upon activation of the pump assembly 164 if wetting is warranted, e.g. owing to the amount of time, for allowing drying of the porous cleaning material 104, that has passed since deactivation of the pump assembly 164.

[0172] Any suitable time period can be used for the given time period, e.g. depending on the drying properties of the porous cleaning material 104. In some embodiments, the given time period is in the range of 20 to 40 minutes, such as about 30 minutes. 2024PF00045 11.08.2025

[0173] 21

[0174] The monitoring system can be implemented in any suitable manner. In some embodiments, the monitoring system comprises electronics having a timer, with the timercomprising electronics being configured to check whether the given time period has elapsed, for example by determining whether the pump assembly 164 was activated during the given time period, e.g. during the past 30 minutes.

[0175] The pump assembly 164 can be configured in any suitable manner in order to enable operation in the cleaning liquid wetting mode and, e.g. subsequently, in the underpressure generating mode. In some embodiments, such as shown in FIGs. 5A and 5B, the pump assembly 164 comprises a pump 167 drivable in a first direction to deliver the cleaning liquid 154 to the liquid pick-up region 161, at the back side 106, in the cleaning liquid wetting mode, and drivable in a second direction opposite the first direction to expose the liquid pick-up region 161, at the back side 106, to the underpressure in the underpressure generating mode.

[0176] This may provide a relatively simple way of implementing the two modes, since the same pump 167 can be used to pump the cleaning liquid 154 in the cleaning liquid delivery mode and to generate the underpressure in the underpressure generating mode.

[0177] In some embodiments, the pump assembly 164 comprises a positive displacement pump, for example a positive displacement pump in the form of a peristaltic pump. Such a positive displacement pump, e.g. peristaltic pump, can, for example, be driven in the first direction in the cleaning liquid wetting mode and in the second direction in the underpressure generating mode.

[0178] In some embodiments, such as shown in FIGs. 5A and 5B, the liquid pick-up region 161, at the back side 106, is exposed to the underpressure via a conduit 168 fluidly connecting the liquid pick-up region 161, at the back side 106, to the pump assembly 164, when the pump assembly 164 is operating in the underpressure generating mode, and the cleaning liquid 154 is supplied to the liquid pick-up region 161, at the back side 106, via the same conduit 168 when the pump assembly 164 is operating in the cleaning liquid wetting mode. Such a design can be relatively straightforward to manufacture, since it can avoid use of multiple conduits being used to deliver the cleaning liquid 154 to the liquid pick-up region 161 in the cleaning liquid wetting mode and to subject the liquid pick-up region 161 to the underpressure in the underpressure generating mode.

[0179] In some embodiments, and still referring to FIGs. 5A and 5B, the pump assembly 164 comprises a valve assembly 169, 170 configured to restrict flow of the cleaning liquid 154 from the cleaning liquid tank 152 towards the liquid pick-up region 161, at the 2024PF00045 11.08.2025

[0180] 22 back side 106, when the pump assembly 164 is operating in the underpressure generating mode. To this end, the valve assembly 169, 170 can include, for example, a first one-way valve 169 that is closed / closes in response to the direction of flow (see arrows 166 in FIG. 5B) that provides the underpressure in the underpressure generating mode.

[0181] In this manner, the valve assembly 169, 170, e.g. the first one-way valve 169 thereof, can assist to minimize or prevent the cleaning liquid 154 from interfering with liquid pick-up during operation of the pump assembly 164 in the underpressure generating mode.

[0182] Alternatively or additionally, the valve assembly 169, 170 may be configured to restrict flow of the dirty liquid 150 collected in the wet cleaning apparatus 100, e.g. in the dirty liquid collection tank 148 thereof, towards the liquid pick-up region 161, at the back side 106, when the pump assembly 164 is operating in the cleaning liquid wetting mode. To this end, the valve assembly 169, 170 can include, for example, a second one-way valve 170 that is closed / closes in response to the direction of flow (see arrows 165 in FIG. 5 A) that delivers the cleaning liquid 154 towards the liquid pick-up region 161, at the back side 106.

[0183] In this way, the valve assembly 169, 170, e.g. the second one-way valve 170 thereof, can assist to minimize or prevent unwanted flow of dirty liquid back towards the back side 106 of the porous cleaning material 104 during operation of the pump assembly 164 in the cleaning liquid wetting mode.

[0184] As shown in FIGs. 5 A and 5B, the porous cleaning material 104 may comprise the cleaning liquid delivery region 160 in addition to the liquid pick-up region 161, with the cleaning liquid delivery system, e.g. the cleaning liquid pump 162 thereof, being configured to deliver the cleaning liquid 154 from the cleaning liquid tank 152 to the cleaning liquid delivery region 160.

[0185] This delivery of the cleaning liquid 154 can, for example, be implemented while the pump assembly 164 is operating in the underpressure generating mode.

[0186] By simultaneously delivering the cleaning liquid 154 towards the surface to be cleaned 158 and picking up liquid from the surface to be cleaned 158, the wet cleaning apparatus 100 can clean the surface 158 without the surface 158 becoming excessively wet.

[0187] In some embodiments, a flow through the porous cleaning material 104 generated by the pump assembly 164 when operating in the underpressure generating mode is equal to or greater than a flow of the cleaning liquid 154 provided by the cleaning liquid delivery system, e.g. the cleaning liquid pump 162 thereof, towards the surface to be cleaned 158. 2024PF00045 11.08.2025

[0188] 23

[0189] More generally, the wet cleaning apparatus 100 can include the cleaning liquid pump 162 for pumping the cleaning liquid 154 from the cleaning liquid tank 152 towards the surface to be cleaned 158, with the cleaning liquid pump 162 being provided in addition to the pump assembly 164, e.g. in addition to the pump 167 included in the pump assembly 164 for providing at least the underpressure generating mode.

[0190] It is noted at this point that the cleaning liquid outlet structure 156 can be implemented in any suitable manner. In embodiments in which the cleaner head 110 comprises the support substrate 114, e.g. the pliable support substrate 114, the cleaning liquid outlet structure 156 may be recessed into and / or embossed on the bottom surface of the support substrate 114, e.g. together with the dirt inlet structure 112.

[0191] In the scenario that the cleaning liquid outlet structure 156 is recessed into the bottom surface of the support substrate 114, the cleaning liquid outlet structure 156 may comprise a groove defined in and extending across at least part of the bottom surface.

[0192] When the cleaning liquid outlet structure 156 is embossed on the bottom surface of the support substrate 114, the cleaning liquid outlet structure 156 may comprise, e.g. be defined by, an arrangement of protruding portions protruding from the bottom surface and extending across at least part of the bottom surface, with path(s) for the cleaning liquid 154 being defined between protruding portions of the arrangement of protruding portions.

[0193] In some embodiments, the cleaning liquid outlet structure 156 comprises at least one cleaning liquid distribution strip, with each of the at least one cleaning liquid distribution strip comprising a channel arranged to receive the cleaning liquid 154 from the cleaning liquid tank 152. Each of the at least one cleaning liquid distribution strip may comprise apertures arranged along its length.

[0194] The channel can, for example, be defined in the bottom surface of the support substrate 114, e.g. in the bottom surface of the pliable support substrate 114.

[0195] The apertures may, for example, be dimensioned such that passage of the cleaning liquid 154, e.g. aqueous cleaning liquid, through the apertures is restricted, due to the surface tension of the cleaning liquid 154, while the channel is being filled with the cleaning liquid 154, but with passage of the cleaning liquid 154 through all of the apertures of the cleaning liquid distribution strip at the same time being permitted once the channel has been filled. This may enable relatively uniform wetting of the surface to be cleaned 158 across the length of the cleaning liquid distribution strip. 2024PF00045 11.08.2025

[0196] 24

[0197] To this end, each aperture may have, for example, a diameter less than 1 mm, for example a diameter in the range of 0.1 to 1 mm, preferably 0.1 to 0.8 mm, most preferably 0.1 to 0.5 mm, such as about 0.3 mm.

[0198] The cleaning liquid distribution strip can be formed of any suitable material, such as a metal, a metal alloy, e.g. stainless steel, and / or a polymer. Forming the cleaning liquid distribution strip from a polymer can make the cleaning liquid distribution strip more lightweight and / or cheaper to manufacture.

[0199] In some embodiments, such as shown in FIGs. 5A and 5B, the cleaning liquid outlet structure 156 comprises a first cleaning liquid outlet portion and a second cleaning liquid outlet portion, with the dirt inlet structure 112 being arranged in-between the first cleaning liquid outlet portion and the second cleaning liquid outlet portion.

[0200] For example, the at least one cleaning liquid distribution strip can include a first cleaning liquid distribution strip and a second cleaning liquid distribution strip, with the dirt inlet structure 112 being arranged in-between the first cleaning liquid distribution strip and the second cleaning liquid distribution strip.

[0201] In other embodiments (not shown), the dirt inlet structure 112 comprises a first dirt inlet portion and a second dirt inlet portion, with the cleaning liquid outlet structure 156 being arranged in-between the first dirt inlet portion and the second dirt inlet portion.

[0202] As shown in FIGs. 5 A and 5B, a cleaning liquid conduit 174 can fluidly connect the cleaning liquid tank 152 to the cleaning liquid outlet structure 156.

[0203] In some embodiments, the porous cleaning material 104 comprises a porous layer and a further porous layer, with at least the liquid pick-up region 161, at the back side 106, being provided by the porous layer, and at least part of the front side 108 being provided by the further porous layer.

[0204] In such embodiments, the further porous layer may, for example, be detachable from the cleaner head 110. Thus, the further porous layer can be detached for cleaning and / or replacement after use.

[0205] The further porous layer can be detachably coupled to the cleaner head 110 in any suitable manner. In some embodiments, the further porous layer is detachable from the cleaner head 110 via a hooks-loops fastening assembly, e.g. Velcro®.

[0206] In such embodiments, part of the hooks-loops fastening assembly can be arranged at an upwardly facing portion of the support substrate 114, such that the further porous layer is required to wrap at least partially around the support substrate 114 in order to fasten to the cleaner head 110. 2024PF00045 11.08.2025

[0207] 25

[0208] In some embodiments, the further porous layer comprises a project ons- comprising side, with the project ons-comprising side comprising projections, e.g. tufts and / or ridges, arranged so that at least some of the projections are contactable with the surface to be cleaned 158. Coarse dirt, e.g. sand, may be accommodated in spaces between the projections, thereby alleviating the risk of scratching of the surface to be cleaned 158. It is also noted that the projections can accommodate unevenness of the surface to be cleaned 158, noting that individual projections can enter recesses, dislocations etc. in the surface to be cleaned 158.

[0209] It is noted at this point that the wet cleaning apparatus 100 can comprise, for example, a wet mopping device, a window cleaner, a sweeper, or a wet vacuum cleaner, such as a stick-type vacuum cleaner, an upright vacuum cleaner, a canister-type vacuum cleaner (see FIG. 6) or a robotic vacuum cleaner (see FIG. 7).

[0210] It is noted that a vacuum cleaner can generate about 20000 Pa of underpressure, and a flow of about 30 L / s (resulting in about 200 W of mechanical power). The above-described liquid pick-up functionality, involving the porous cleaning material 104, may only require an underpressure of >5000 Pa and a flow of about 250 cm3 / minute (resulting in roughly 0.02 W of power). This means that the liquid pick-up functionality can easily be implemented using the vacuum cleaner.

[0211] However, it is alternatively contemplated that the pump assembly 164 may be configured to generate a flow through the porous cleaning material 104 that is at most 2000 cm3 / minute when the pump assembly 164 is being operated in the underpressure generating mode.

[0212] Alternatively or additionally, a pressure difference, when the pump assembly 164 is operating in the underpressure generating mode, between an inside of the wet cleaning apparatus 100 and atmospheric pressure may be in a range of 3000 Pa to 13500 Pa, preferably 5000 Pa to 9000 Pa, most preferably 7000 Pa to 9000 Pa.

[0213] The pressure difference can be directly and positively verified in a given wet cleaning apparatus 100 by, for example, drilling a hole in a tube of the wet cleaning apparatus 100 which is fluidly connected to the back side 106 of the porous cleaning material 104 and using the hole to couple to a pneumatic pressure sensor itself having a tube with a membrane covering an end thereof; the sensor being thus connected using an airtight connection. The sensor may be arranged to avoid disturbing the flow, hence the skilled person will arrange the sensor to avoid, for instance, creating a bypass flow. No flow may be towards or from the 2024PF00045 11.08.2025

[0214] 26 sensor: only pressure is transmitted. In this way, the flow of the appliance may never be compromised (hence may remain at the set level in spite of the sensor installation).

[0215] The pressure sensor is connected between the porous cleaning material 104 and the pump assembly 164 and as close to the porous cleaning material 104 as possible, to minimise the influence of other factors, such as flow resistance etc., on the sensed pressure difference.

[0216] The sensing element / membrane of the pressure sensor / gauge is ideally arranged / positioned in the pressure sensor so that the sensing element can be placed directly (without the requirement for connecting tubes) in the tube, or in a cavity behind the porous cleaning material 104.

[0217] By positioning the membrane of the pressure sensor, in other words membrane pressure gauge, with the membrane positioned at, in other words in line with, the wall of the tube (or exposed to the cavity), measurement errors may be minimized, as will be appreciated by a person skilled in the art.

[0218] It is noted that air bubbles inside narrow tubes may generate resistance (capillary / surface tension effects), and hence may influence the measurement. Hence the skilled person will further appreciate that care is also to be taken that air bubbles (water-air surfaces) do not unduly influence the pressure difference measurement.

[0219] It is further noted that a column of water present between the pressure sensor and the porous cleaning material 104 should be deducted from the measurement result (if such a column of water is present during the measurement), to compensate for the static pressure generated by the column of water.

[0220] Once the pressure sensor is arranged as described above, it may be ascertained that maintenance of the underpressure is due to the porous cleaning material 104 and not some other element, such as a valve. Any such element that influences the underpressure that is presented to the porous cleaning material 104 should be rendered inoperable for the purpose of performing the measurement.

[0221] Component(s) that dispense cleaning liquid is / are disengaged when performing the pressure difference measurement.

[0222] The wet cleaning apparatus 100 is turned on (in the desired setting) and the pumping assembly 164 is operated in the underpressure generating mode, so that the pick-up system is activated. Recording of data from the pressure sensor is started.

[0223] The pick-up area of the wet cleaning apparatus 100 is suspended in a layer of water, at max. 5 mm depth. 2024PF00045 11.08.2025

[0224] 27

[0225] The pick-up area is then lifted from the water without tilting it in any way (so that the cleaner head 110 remains in a cleaning position, as if it were positioned to clean the floor), so that the water is no longer touching the porous cleaning material 104. At this point, “free water” will be removed from the porous cleaning material 104, all pores 118 will go into their “blocked state”, and the breaking pressure is determinable. The measurement result will resemble the graph shown in FIG. 3, once again noting that an equilibrium is established in the end regime 146 in which the applied flow results in an underpressure which causes no more fluid blocks to break.

[0226] The breaking pressure obtained from this measurement result, referring to the end regime 146, is the “pressure difference between the inside of the wet cleaning apparatus 100 and atmospheric pressure for drawing fluid through the porous cleaning material 104.” It is verified from the measurement result whether or not the 3000 Pa to 13500 Pa range is satisfied.

[0227] It is noted that the porous cleaning material 104 may be arranged to contact liquid on the surface to be cleaned 158, as previously described. Thus, the porous cleaning material 104 may be defined from the front side 108 of the porous cleaning material 104 exposable to liquid on the surface to be cleaned 158 to the back side 106 exposed to the underpressure.

[0228] The vacuum cleaner-comprising wet cleaning apparatus 100 shown in FIG. 6, and in particular the porous cleaning material 104 thereof, can be moved over the surface to be cleaned 158 during vacuuming as well as when applying the cleaning liquid 154 to the surface to be cleaned 158. Such movement can be assisted, for example, by wheels 184 included in the vacuum cleaner.

[0229] The wet cleaning apparatus 100 may in some examples be or comprise a robotic vacuum cleaner or a robotic wet mopping device configured to autonomously move on the surface to be cleaned 158, such as the surface of a floor.

[0230] FIG. 7 schematically depicts an exemplary wet cleaning apparatus 100 comprising a robotic vacuum cleaner. The robotic vacuum cleaner may move autonomously on the surface to be cleaned 158, e.g. via automated control over the wheels 184.

[0231] The cleaning liquid stored in the cleaning liquid tank 152 can be delivered to the surface to be cleaned 158, and liquid can be picked up via the porous cleaning material 104 and collected in the dirty liquid collection tank 148, during autonomous movement of the robotic vacuum cleaner. The pump assembly 164 may also be under automated control. 2024PF00045 11.08.2025

[0232] 28

[0233] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0234] If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to".

[0235] Any reference signs in the claims should not be construed as limiting the scope.

Claims

2024PF00045 11.08.202529CLAIMS1. A wet cleaning apparatus (100) comprising: a porous cleaning material (104) comprising a front side (108) for contacting a surface to be cleaned (158), and a back side (106) that faces away from the front side; a cleaning liquid tank (152) for containing cleaning liquid (154); characterized by a pump assembly (164) configured to operate in: an underpressure generating mode in which a liquid pick-up region (161) of the porous cleaning material is exposed, at the back side, to an underpressure generated by the pump assembly to enable liquid on the surface to be cleaned to be drawn into pores (118) of the porous cleaning material, the porous cleaning material being arranged to enable the front side to maintain contact with the surface to be cleaned irrespective of how long the pump assembly is operated in the underpressure generating mode; a cleaning liquid wetting mode in which cleaning liquid is delivered by the pump assembly from the cleaning liquid tank to the liquid pick-up region, at the back side, to wet the pores of the porous cleaning material with the cleaning liquid; the pump assembly (164) comprises a pump (167) drivable in a first direction to deliver the cleaning liquid (154) to the liquid pick-up region (161), at the back side (106), in the cleaning liquid wetting mode, and drivable in a second direction opposite the first direction to expose the liquid pick-up region, at the back side, to the underpressure in the underpressure generating mode.

2. The wet cleaning apparatus (100) according to claim 1, wherein the pump assembly (164) comprises at least one positive displacement pump.

3. The wet cleaning apparatus (100) according to any one of claims 1 to 2, wherein the pump assembly (164) comprises a valve assembly (169, 170) configured to: restrict flow of cleaning liquid (154) from the cleaning liquid tank (152) towards the liquid pick-up region (161), at the back side (106), when the pump assembly is operating in the underpressure generating mode; and / or restrict flow of dirty liquid (150) collected in the wet cleaning apparatus towards the liquid pick-up region, at the back side, when the pump assembly is operating in the cleaning liquid wetting mode.2024PF00045 11.08.2025304. The wet cleaning apparatus (100) according to any one of claims 1 to 3, wherein the pump assembly (164) is configured to switch automatically from initially operating in the cleaning liquid wetting mode to subsequently operating in the underpressure generating mode.

5. The wet cleaning apparatus (100) according to any one of claims 1 to 4, wherein the pump assembly (164) is configured to: initially operate in the cleaning liquid wetting mode for a given time period and / or until a given amount of cleaning liquid (154) has been delivered to the liquid pick-up region (161), at the back side (106), and automatically switch from operating in the cleaning liquid wetting mode to operating in the underpressure generating mode subject to the given time period having elapsed and / or the given amount of cleaning liquid having been delivered to the liquid pickup region, at the back side.

6. The wet cleaning apparatus (100) according to any one of claims 1 to 5, wherein the pump assembly (164) is configured to initially operate in the cleaning liquid wetting mode upon activation of the pump assembly.

7. The wet cleaning apparatus (100) according to any one of claims 1 to 6, comprising a cleaning liquid delivery system configured to deliver the cleaning liquid (154) from the cleaning liquid tank (152) towards the surface to be cleaned (158) at least when the pump assembly (164) is operating in the underpressure generating mode.

8. The wet cleaning apparatus (100) according to claim 7, wherein the porous cleaning material (104) comprises a cleaning liquid delivery region (160) in addition to the liquid pick-up region (161), wherein the cleaning liquid delivery system is configured to deliver the cleaning liquid (154) from the cleaning liquid tank (152) to the cleaning liquid delivery region.

9. The wet cleaning apparatus (100) according to any one of claims 1 to 8, comprising a cleaning liquid pump (162) for pumping cleaning liquid (154) from the cleaning liquid tank (152) towards the surface to be cleaned (158); optionally wherein the cleaning liquid pump is provided in addition to the pump assembly (164).2024PF00045 11.08.20253110. The wet cleaning apparatus (100) according to any one of claims 1 to 9, wherein the porous cleaning material (104) comprises a porous layer and a further porous layer, at least the liquid pick-up region (161), at the back side (106), being provided by the porous layer, and at least part of the front side (108) being provided by the further porous layer.

11. The wet cleaning apparatus (100) according to claim 10, wherein the further porous layer comprises a project! ons-comprising side, at least some of the projections of the projections-comprising side being arranged for contacting the surface to be cleaned (158).

12. The wet cleaning apparatus (100) according to any one of claims 1 to 11, wherein the liquid pick-up region (161), at the back side (106), is exposed to the underpressure via a conduit (168) fluidly connecting the liquid pick-up region, at the back side, to the pump assembly (164), when the pump assembly is operating in the underpressure generating mode, and wherein the cleaning liquid (154) is deliverable to the liquid pick-up region, at the back side, via the same conduit when the pump assembly is operating in the cleaning liquid wetting mode.

13. The wet cleaning apparatus (100) according to any one of claims 1 to 12, wherein the pump assembly (164) is configured to, when being operated in the underpressure generating mode: provide a pressure difference between an inside of the wet cleaning apparatus and atmospheric pressure for drawing fluid through the porous cleaning material (104), with the pressure difference being in a range of 3000 Pa to 13500 Pa; and / or generate a flow through the porous cleaning material that is at most 2000 cm3 / minute.

14. The wet cleaning apparatus (100) according to any one of claims 1 to 13, comprising a wet mopping device, a window cleaner, a sweeper, or a wet vacuum cleaner.

Images