Wet cleaning device

Abstract

A wet cleaning device (278) is provided, comprising a cleaning head (100) and an underpressure generator device (280). The cleaning head has at least one dirty inlet (142A) and a porous material (168) covering the at least one dirty inlet. The underpressure generator device comprises an underpressure generator (178) configured to provide a flow rate inside the wet cleaning device for sucking fluid through the porous material into the at least one dirty inlet. The underpressure generator device is configured to control the flow rate based on the pressure on the inside of the wet cleaning device between the porous material and the underpressure generator.

Description

Technical Field

[0001] The present invention relates to a wet cleaning device, such as a wet mopping device, including a cleaning head. The wet cleaning device can be used, for example, to clean floors, indoor surfaces or windows. Background Art

[0002] Wet cleaning devices for removing water from a surface to be cleaned are known, such as wet mopping devices. Such wet cleaning devices can also apply a cleaning liquid, such as water, to the surface to be cleaned and then remove the liquid, for example, with a suitable cloth.

[0003] Some wet cleaning devices have a power pick-up function for removing water from the surface to be cleaned. For example, a wet vacuum cleaner can suck up the liquid by generating a sufficient airspeed (e.g., at least 10 m / s) and / or brush force to apply sufficient shear force on the droplets so that the droplets enter the device. The typical power consumption value of such a vacuum cleaner is relatively high, for example, in the order of several hundred watts.

[0004] When a wet cleaning device is arranged to deliver a cleaning liquid and use suction to suck up the liquid, further challenges arise. In at least some designs, providing these two functions may pose a risk of inefficient use of the cleaning liquid.

[0005] During or even after use, there may also be a risk that the uncontrolled delivery of the cleaning liquid causes the environment to be soaked with the cleaning liquid. In at least some cases, especially when a relatively low-power pick-up system is employed, such soaking of the surface to be cleaned may not be easily resolved by the pick-up function of the device.

[0006] In some designs, the pick-up function may also pose a risk of hindering the movement of the cleaning head of such a wet cleaning device on the wet surface to be cleaned.

[0007] US2019 / 380553 A1 discloses a cleaning device including a surface interaction layer, a cleaning fluid supply device having a cleaning fluid channel provided at the surface interaction layer for supplying a cleaning fluid to the surface through the surface interaction layer in contact with the surface. The cleaning device further includes a dirty fluid discharge device having a dirty fluid channel at the surface interaction layer for discharging dirty water from the surface through the surface interaction layer in contact with the surface by means of underpressure.

[0008] KR 940 001 037Y1 discloses a vacuum cleaner having a wet dust collector.

[0009] WO 2016 / 008773 A1 discloses a surface cleaning device, which includes a cloth placed on a porous material, a reservoir for collecting the liquid absorbed by the cloth, and a device for applying a negative pressure in the reservoir to transfer the liquid from the cloth to the reservoir. The pore diameter of the porous material is between 1 μm and 50 μm.

[0010] DE 102013223864 A1 discloses a method for operating a vacuum cleaner, which has a fan with a fan motor that generates an air flow through the nozzle of the vacuum cleaner. The control device of the vacuum cleaner controls the fan according to the type of floor covering to be treated.

[0011] DE 102007059930 B3 discloses a device for controlling or regulating the motor power of a vacuum cleaner, which has at least one motor, a dust separation device, and a nozzle. The device uses a first sensor to detect the negative pressure in the nozzle area.

[0012] DE 102011078388 A1 discloses a secondary air valve for a vacuum cleaner, which has a housing, an inlet opening for the secondary air flow, an outlet opening for the secondary air flow, and a pressure-dependent closing device for blocking the flow connection between the inlet opening and the outlet opening. A vacuum cleaner is also disclosed, which has a nozzle, a suction fan connected to the nozzle, a dust separation device arranged in the flow channel, a pressure sensor with an electrical or electronic interrogation device, and a secondary air valve for selectively supplying the secondary air flow to the suction channel. Summary of the Invention

[0013] The present invention is defined by the claims.

[0014] According to an example of one aspect of the present invention, a wet cleaning device is provided, which includes: a cleaning head having at least one dirt inlet and a porous material covering the at least one dirt inlet; and a negative pressure generator device including a negative pressure generator configured to provide a flow rate inside the wet cleaning device for sucking a fluid through the porous material into the at least one dirt inlet, wherein the negative pressure generator device is configured to control the flow rate based on the pressure on the inside of the wet cleaning device between the porous material and the negative pressure generator.

[0015] The porous material can be arranged to contact the liquid on the surface to be cleaned.

[0016] The porous material can include, for example, porous fabric and / or porous foam. The porous fabric can be, for example, a microfiber fabric.

[0017] The surface tension of the liquid retained in the pores of the porous material can contribute to maintaining underpressure. This surface tension can be overcome, which means that the air-liquid surface is removed at a point (or points) on the outside of the porous material in contact with the liquid on the surface to be cleaned, such that the liquid is transported through the porous material in the direction of the (multiple) dirt inlets.

[0018] By controlling the flow based on the pressure on the inside between the porous material and the underpressure generator of the wet cleaning device by means of an underpressure generator device, the fluid transport through the porous material can be advantageously controlled. In some non-limiting examples, such control can minimize foam accumulation in and downstream of the porous material.

[0019] In some embodiments, the underpressure generator device is configured to control the flow rate such that the pressure is maintained at or above a predetermined pressure threshold.

[0020] By controlling the flow rate to maintain the pressure at or above a predetermined threshold, stable and efficient operation of the wet cleaning device can be promoted. In particular, maintaining the pressure at or above a predetermined threshold can mean that the underpressure generator can operate more efficiently, for example by being intermittently deactivated / disconnected, and thus utilize the above-described ability of the porous material to help maintain the underpressure in the covered (multiple) dirt inlets.

[0021] Each pore of the porous material can have a certain bursting pressure at which the surface tension of the (residual) liquid present in the pore can no longer withstand the internal underpressure and gives way. When this occurs, the pore may no longer be effectively sealed by the liquid contained therein, but may start to transport air into the (multiple) dirt inlets. When the cleaning liquid contains a foaming detergent, problems may accordingly arise. The burst pores may start to transport air at the rate of the underpressure generator (such as a pump), which may risk generating a relatively large amount of foam at the dirt inlets and downstream thereof.

[0022] Therefore, the above-mentioned predetermined pressure threshold can be set, for example, to avoid reaching the bursting pressure of at least some pores (such as most or all pores) of the porous material. When using a detergent, this helps to avoid operational problems related to foam.

[0023] The predetermined pressure threshold can be set accordingly to limit the underpressure, in other words, the pressure difference between the inside between the porous material and the underpressure generator of the wet cleaning device and the outside of the cleaning head (such as atmospheric pressure), to a value in the range of, for example, at most 2000 Pa to 13500 Pa, preferably 2000 Pa to 12500 Pa, more preferably 5000 Pa to 9000 Pa, and most preferably 7000 Pa to 9000 Pa.

[0024] The breaking pressure of the porous material can be considered negative (with reference to atmospheric pressure). Accordingly, the pressure inside the wet cleaning device between the porous material and the underpressure generator can be maintained above this negative pressure. On the other hand, if the breaking pressure of the porous material is an absolute pressure (with reference to a vacuum, 0 Pa), it is still possible to maintain the pressure inside the wet cleaning device between the porous material and the underpressure generator above such an absolute pressure, in particular by controlling the flow rate to keep the pressure at or above a predetermined threshold.

[0025] In some embodiments, the underpressure generator device includes: a sensor and a controller, the sensor being arranged to sense a measured value of the pressure in at least one covered dirt inlet, and the controller being configured to control the underpressure generator to provide fluid based on the measured value of the pressure.

[0026] The controller, such as a microcontroller, can receive a sensor signal from the sensor and send a control signal to the underpressure generator based on the sensor signal. For example, the control signal can trigger the underpressure generator to activate to provide flow or deactivate to stop flow. Alternatively or additionally, the control signal can increase or decrease the flow rate according to the sensor signal.

[0027] The deactivation or reduction of the flow rate provided by the underpressure generator in this way can contribute to reducing the power consumption of the wet cleaning device. This can help to conserve battery power in examples where the wet cleaning device is battery-powered / battery-operable and thereby increase the runtime.

[0028] In embodiments where the underpressure generator includes a controller and a sensor, the controller can be configured to control the flow rate provided by the underpressure generator such that the pressure in at least one covered dirt inlet is maintained at or above the aforementioned predetermined pressure threshold.

[0029] In a non-limiting example, the controller (e.g., including a proportional-integral controller or in the form of a proportional-integral controller) is configured to compare the sensed pressure measurement with a desired operating pressure and control the underpressure generator based on this comparison.

[0030] In some embodiments, the sensor is configured to sense a measured value of the pressure in at least one of the following: the cavity between the porous material and at least one dirt inlet, and the tube connecting at least one dirt inlet to the underpressure generator.

[0031] Sensing the measured value of the pressure in the cavity can be particularly advantageous because the flow rate can be tuned more directly to the characteristics of the porous material during use.

[0032] Arranging the sensor such that a measured value of the pressure is sensed in the tube can provide a relatively straightforward way of incorporating the sensor into the wet cleaning device.

[0033] The sensor can be any suitable type of sensor, as long as the sensor is capable of sensing the measured value of the pressure on the inner side between the porous material and the underpressure generator of the wet cleaning device. For example, the sensor includes a pressure sensor, such as a microelectromechanical systems (MEMS) pressure sensor.

[0034] In some embodiments, the underpressure generator device includes a mechanical regulator that is configured to control the flow rate based on the pressure on the inner side between the porous material and the underpressure generator of the wet cleaning device. Such a mechanical regulator can provide a relatively simple, robust, and inexpensive control of the flow rate based on the pressure in the covered (multiple) dirt inlets.

[0035] In a non-limiting example, the mechanical regulator includes a switch and a deflectable member, the actuation of the switch controls the underpressure generator, and the deflectable member is, for example, a diaphragm that is configured to actuate the switch in response to pressure.

[0036] Such a mechanical regulator, in this case an electromechanical regulator, can be configured such that when, for example, the pressure is at or above a predetermined pressure threshold, the switch is actuated by the membrane, for example to deactivate the underpressure generator.

[0037] Such a switch - membrane device can provide a simple and inexpensive way to control the flow rate based on pressure without the need for an additional controller, such as a microcontroller.

[0038] In some embodiments, the mechanical regulator includes a valve that is arranged to control the fluid communication between the underpressure generator and at least one dirt inlet.

[0039] In such an embodiment, the valve can include a valve seat and a valve member that is configured to adopt an initial position and a closed position. In the initial position, the valve member is separated from the valve seat to allow fluid communication between the underpressure generator and at least one dirt inlet. In the closed position, the valve member abuts against the valve seat to restrict the fluid communication between the underpressure generator and at least one dirt inlet, and in some examples blocks the fluid communication.

[0040] For example, the valve member can be in the form of a flexible rubber membrane that adopts an undeflected profile in the initial position and thus is spatially displaced from the valve seat when there is no underpressure in the covered (multiple) dirt inlets. After starting the underpressure generator (such as a pump), an underpressure can be generated in the covered (multiple) dirt inlets and the mechanical regulator. The underpressure can act on the exposed surface of the rubber membrane in the mechanical regulator, and the exposed surface of the rubber membrane can thus begin to deflect inward in the direction of the valve seat, causing the valve to transition towards the closed position.

[0041] In some embodiments, the valve is configured such that when the pressure is below a predetermined pressure threshold, the valve member is caused to move against the valve seat by the pressure in at least one covered dirt inlet.

[0042] In a non - limiting example where the valve member is in the form of a flexible rubber membrane, the threshold pressure can be set / pre - determined at least in part by the distance between the flexible rubber membrane and the valve seat. The greater the distance, the higher the under - pressure (or equivalently, the lower the pressure) in the covered (s) dirt inlet required to deform the rubber membrane to contact the valve seat.

[0043] In some embodiments, the limiting pore diameter of the porous material measured using ASTM F316 - 03, 2019, Test A is equal to or greater than 15 μm.

[0044] It has been found empirically (as further described below) that a limiting pore diameter equal to or greater than 15 μm can help maintain a relatively large under - pressure while ensuring that the pores are large enough to effectively transport liquid through. Regarding the latter, it is noted that this observation is supported by theory, noting that when using the Poiseuille equation approximation, for smaller pores, the flow resistance can increase to the fourth power.

[0045] Similarly, the bubble - point pressure of the porous material measured using ASTM F316 - 03, 2019, Test A can be equal to or less than 13500 Pa.

[0046] In some embodiments, the limiting pore diameter of the porous material measured using ASTM F316 - 03, 2019, Test A is equal to or less than 105 μm. Limiting the upper limit of the pore diameter helps ensure that the porous material can maintain sufficient under - pressure.

[0047] Similarly, the bubble - point pressure of the porous material measured using ASTM F316 - 03, 2019, Test A can be equal to or greater than 2000 Pa.

[0048] In some embodiments, the limiting pore diameter of the porous material measured using ASTM F316 - 03, 2019, Test A is equal to or greater than 15 μm and equal to or less than 105 μm.

[0049] Limiting the flow rate to an upper limit can help minimize the risk that the pores cannot withstand the under - pressure and thus "burst", resulting in a large amount of air entering the interior of the wet cleaning device, which in turn may require a larger pump that consumes more power.

[0050] In some embodiments, the under - pressure generator is configured to provide a flow rate through the porous material of less than or equal to 2000 cm 3 / minute.

[0051] This flow rate can be significantly lower than that of the above-mentioned conventional wet vacuum cleaners. Since power is equal to the flow rate multiplied by the pressure difference, by combining this maximum flow rate of 2000 cm 3 / minute (0.03 l / s) with the above-mentioned maximum pressure difference of 13,500 Pa as the maximum power consumption scenario, the power consumption of the wet cleaning device can be minimized. This can enable the wet cleaning device to be manufactured relatively compactly, for example, using a smaller battery, and / or to have a relatively long operating time.

[0052] Alternatively or additionally, the underpressure generator can be configured to provide a flow rate through the porous material that is equal to or greater than 15 cm 3 / minute.

[0053] This can help pick up liquid from the surface to be cleaned quickly enough. In some embodiments, the lower limit of 15 cm 3 / minute can be set to be equal to or exceed the flow rate of the cleaning liquid from the cleaning liquid outlet(s) also included in the cleaning head.

[0054] More generally, the underpressure generator can be configured such that when providing a flow rate, the flow rate is in the range of 15 cm 3 / minute to 2000 cm 3 / minute, preferably in the range of 40 cm 3 / minute to 2000 cm 3 / minute, more preferably in the range of 80 cm 3 / minute to 750 cm 3 / minute, and most preferably in the range of 100 cm 3 / minute to 300 cm 3 / minute.

[0055] This flow, i.e., the flow rate, can utilize the underpressure holding ability of the porous material and can ensure sufficient liquid pickup while limiting energy consumption.

[0056] In some embodiments, the underpressure generator includes a pump that is configured to control the flow rate for sucking fluid through the porous material into at least one dirt inlet in response to the pressure in the covered dirt inlet device.

[0057] In such an embodiment, it can be the underpressure generator / pump itself that controls the flow rate in response to the pressure in the covered dirt inlet device.

[0058] Such a pump can be considered a pressure-limiting pump. A pressure-limiting pump is capable of generating a certain pressure difference across the tube to which it is connected. In principle, the pump pressure can be tuned to the pressure required for the porous material covering the dirt inlet(s).

[0059] The pump, such as a pressure-limiting pump, can include or be, for example, a centrifugal pump.

[0060] Alternatively or additionally, the pump may include a liquid pump disposed in the cleaning head.

[0061] By disposing the liquid pump in the cleaning head, e.g., as opposed to in or on a handle coupled to the cleaning head, the height and (static) pressure of the pump may be independent of the orientation of the handle relative to the floor.

[0062] In an alternative example, the liquid pump may be disposed in a handle coupled to the cleaning head. This may facilitate the manufacture of the wet cleaning device as there may be more available space in the handle for the liquid pump than in the cleaning head.

[0063] In some embodiments, the wet cleaning device includes a dirty liquid collection tank for collecting liquid, wherein the underpressure generating means is arranged such that the flow draws liquid from the at least one dirty inlet into the dirty liquid collection tank.

[0064] For example, the liquid pump described above may be disposed between the dirty inlet and such a dirty liquid collection tank.

[0065] Alternatively or additionally, the pump may include an air pump disposed downstream of the dirty liquid collection tank.

[0066] In at least some embodiments, the porous material includes a porous material layer sealingly attached to the at least one dirty inlet. This may help to maintain an underpressure in the dirty inlet with or without a flow applied by the underpressure generator included in the wet cleaning device.

[0067] The liquid pickup area of the porous material layer may be defined, for example, by a sealed connection of the porous material layer around each dirty inlet in the at least one dirty inlet.

[0068] The sealed connection may be achieved in any suitable manner, e.g., by gluing or welding the porous material layer around each dirty inlet in the at least one dirty inlet, e.g., by gluing and / or welding the porous material layer around one or more tubes, the (multiple) openings of which define the dirty inlet. In some non-limiting examples, an impermeable portion (e.g., a polymer film) is sealed to the surface of the porous material layer that is exposed to the (multiple) dirty inlets and around the (multiple) dirty inlets.

[0069] In some embodiments, the porous material includes one or more additional porous material layers.

[0070] In addition to the porous material layer sealingly attached to the dirty inlet, including one or more additional porous material layers may help to increase the underpressure that can be maintained in the dirty inlet. This in turn helps to operate the above-described underpressure generator more effectively.

[0071] Such additional layer(s) of porous material may be arranged, for example, on the outer surface of the porous material layer such that the outer surface of the additional layer of porous material that is furthest from at least one dirt inlet in the thickness direction of the porous material contacts the surface to be cleaned.

[0072] In some embodiments, the porous material has a thickness less than or equal to 10 mm, more preferably less than or equal to 5 mm, and most preferably less than or equal to 3 mm. Such a maximum thickness can help to minimize the flow resistance through the porous material.

[0073] In some embodiments, the fluid delivery pressure for fluid flowing through the porous material at 200 cm 3 / minute is less than 0.25 times the bubble point pressure as determined by ASTM F316 - 03, 2019, Test A.

[0074] This may mean that the flow resistance through the porous material remains at a relatively low level.

[0075] In some embodiments, the porous material includes one or more of porous fabric, porous plastic, and foam.

[0076] Such porous plastic may take the form of a sintered mesh of plastic particles, for example.

[0077] In embodiments where the porous material includes such porous plastic, one or more additional layers of porous material, for example including porous fabric, such as woven porous fabric, may be arranged on the outer surface of the porous plastic. Such additional layer(s) of porous material may be more wettable by water than the porous plastic and thus more suitable for contacting the surface to be cleaned when wetted by water.

[0078] Particularly mentioned porous materials include porous woven fabric, most preferably woven microfiber fabric. Such woven microfiber fabric can facilitate obtaining the required underpressure in a wet cleaning device.

[0079] Such porous woven fabric, especially such woven microfiber fabric, can be configured, in particular, by its weaving tightness to meet the above range of limiting diameters.

[0080] In some embodiments, the cleaning head includes at least one cleaning liquid outlet through which cleaning liquid can be delivered.

[0081] The wet cleaning device may include a cleaning liquid supply that includes a cleaning liquid reservoir for containing the cleaning liquid, the cleaning liquid reservoir being able to be in fluid communication or in fluid communication with the at least one cleaning liquid outlet.

[0082] Such a cleaning liquid supply may include, for example, a cleaning liquid reservoir and a delivery device, such as a delivery device including a pump, for transporting the cleaning liquid to and through at least one cleaning liquid outlet.

[0083] The cleaning liquid supply and the at least one cleaning liquid outlet may be configured, for example, to provide a continuous delivery of the cleaning liquid towards the surface to be cleaned. Such continuous delivery may be provided, for example, while a negative pressure generator supplies fluid.

[0084] In some embodiments, the cleaning liquid supply includes a pump arranged to pump the cleaning liquid from the cleaning liquid reservoir to and through the at least one cleaning liquid outlet.

[0085] In some embodiments, the cleaning liquid supply and the negative pressure generator are configured such that the flow rate of the cleaning liquid delivered through at least one cleaning liquid outlet is lower than the flow rate provided by the negative pressure generator to at least one dirt inlet.

[0086] This helps to ensure that the surface to be cleaned is not overly wetted by the cleaning liquid. For example, the flow rate of the cleaning liquid may be in the range of 20 cm 3 / minute to 60 cm 3 / minute, the flow rate provided by the negative pressure generator may be in the range of 40 cm 3 / minute to 2000 cm 3 / minute, more preferably in the range of 80 cm 3 / minute to 750 cm 3 / minute, and most preferably in the range of 100 cm 3 / minute to 300 cm 3 / minute.

[0087] In at least some embodiments, the wet cleaning device is a wet mopping device.

[0088] In other examples, the wet cleaning device may be or include, for example, a window cleaner, a sweeper, or a wet vacuum cleaner, such as a canister, stick, or upright wet vacuum cleaner.

[0089] In some examples, the wet cleaning device may be or include a robotic wet vacuum cleaner or a robotic wet mopping device configured to autonomously move, for example, a cleaning head on a surface to be cleaned (such as the surface of a floor) in one cleaning direction.

[0090] The wet cleaning device may be a battery-powered wet cleaning device, where the negative pressure generator may be powered by a battery electrically connected to the negative pressure generator.

[0091] The power consumption reduction effect provided by the porous material that can cover the dirty inlet sucking the under-voltage generator can make the wet cleaning device particularly suitable for battery-powered operation.

[0092] The embodiments described herein with respect to the cleaning head can be applied to the wet cleaning device, and the embodiments described herein with respect to the wet cleaning device can be applied to the cleaning head. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] Examples of the present invention will now be described in detail with reference to the accompanying drawings, in which:

[0094] Figure 1 The underside of a cleaning head according to one example is schematically shown;

[0095] Figure 2 A schematic cross-sectional view of a cleaning liquid distribution belt included in the Figure 1 shown cleaning head is provided;

[0096] Figure 3 The underside of a cleaning head according to a second example is schematically shown, in which the cleaning liquid applicator material is separated from the cleaning head;

[0097] Figure 4 The Figure 3 underside of the shown cleaning head is schematically shown, to which a cleaning liquid applicator fabric is attached;

[0098] Figure 5A The porous material layer and the dirty inlet of an exemplary cleaning head are schematically shown;

[0099] Figure 5B A Figure 5A schematic cross-sectional view of the porous material layer and the dirty inlet shown is provided;

[0100] Figure 6A An example of a sealed attachment of a porous material layer around a dirty inlet is schematically depicted;

[0101] Figure 6B A Figure 6A schematic cross-sectional view of the exemplary sealed attachment shown in

[0102] Figure 7A The Figure 6A and Figure 6B variant of the sealed attachment shown in

[0103] Figure 7B A Figure 7A schematic cross-sectional view of the exemplary sealed attachment shown is provided;

[0104] Figure 8 A Figure 7A andFigure 7B Schematic cross-sectional view of a variant of a sealed attachment as shown;

[0105] Figure 9 There is provided Figure 8 Schematic cross-sectional view of a variant of a sealed attachment as shown;

[0106] Figure 10 Schematic of fluid transport through three exemplary porous materials is provided;

[0107] Figure 11 A test arrangement for testing the behavior of a porous material when liquid is applied to it and suction is applied is schematically shown;

[0108] Figure 12 There is provided a graph of underpressure versus time of data obtained from using Figure 11 the test arrangement shown;

[0109] Figure 13 Several pressure-time graphs of porous materials including different numbers of layers of porous material are provided;

[0110] Figure 14 The liquid transport state, intermediate state, and end state sequence of a porous material when suction is applied to the porous material are schematically shown;

[0111] Figure 15 Several pressure-time graphs of porous materials with different pore sizes are provided;

[0112] Figure 16 An exemplary cleaning head moving on a surface to be cleaned is schematically shown;

[0113] Figures 17 to 23 A schematic cross-sectional view of a porous material mounted on a support member is provided;

[0114] Figures 24 to 30 Various exemplary cleaning heads are schematically shown;

[0115] Figure 31 An exemplary cleaning head that can swing on a protruding element so that a part of the lower side of the cleaning head contacts the surface to be cleaned is schematically shown;

[0116] Figure 32A An example of a sealed attachment of a porous material layer around a dirt inlet is schematically depicted;

[0117] Figure 32B There is provided Figure 32A a schematic cross-sectional view of the exemplary sealed attachment shown;

[0118] Figure 33AA view of the end of a cleaning head according to an example is provided;

[0119] Figure 33B A view of the top side of the cleaning head shown is provided; Figure 33A is provided;

[0120] Figure 33C A schematic cross-sectional view of a protruding element / separable member according to an example is provided;

[0121] Figure 33D A schematic cross-sectional view of a protruding element / separable member according to another example is provided;

[0122] Figure 33E A schematic cross-sectional view of an exemplary separable element including (a plurality of) additional porous material layers and a cleaning liquid applicator material is provided;

[0123] Figure 33F A perspective view of a cleaning head including Figure 33C or the protruding element / separable member shown in 33D and Figure 33E the separable element shown is provided;

[0124] Figure 34 An exemplary wet cleaning device is schematically shown before (left square), during (central square), and after (right square) sucking liquid through the porous material;

[0125] Figure 35 An exemplary wet cleaning device having a negative pressure generator is schematically shown, where the negative pressure generator is activated (left hand square) and deactivated (right hand square);

[0126] Figure 36 A negative pressure generator in the form of a peristaltic pump is schematically shown;

[0127] Figure 37A The pores of the porous material layer of an exemplary wet cleaning device are schematically shown;

[0128] Figure 37B is schematically shown Figure 37A the foam accumulation in the wet cleaning device shown;

[0129] Figure 37C The operating window of the wet cleaning device is graphically shown, particularly when the wet cleaning device is started;

[0130] Figure 38 An exemplary wet cleaning device is schematically shown, which includes a negative pressure generator device having a negative pressure generator, a pressure sensor, and a controller;

[0131] Figure 39Schematically shows an exemplary wet cleaning device having an underpressure generator device, the underpressure generator device having an underpressure generator and a mechanical regulator;

[0132] Figure 40 Schematically shows an exemplary wet cleaning device, the underpressure generator of which comprises a pressure-limiting liquid pump;

[0133] Figure 41 Schematically shows an exemplary wet cleaning device, the underpressure generator of which comprises a pressure-limiting air pump;

[0134] Figure 42 Schematically shows an exemplary wet cleaning device in the form of a wet vacuum cleaner; and

[0135] Figure 43 Schematically shows an exemplary wet cleaning device in the form of a robotic wet vacuum cleaner. Detailed Description

[0136] The present invention will be described with reference to the accompanying drawings.

[0137] It should be understood that the detailed description and specific examples, although indicating exemplary embodiments of the device, system and method, are for illustrative purposes only and are not intended to limit the scope of the present invention. These and other features, aspects and advantages of the device, system and method of the present invention will become better understood from the following description, the appended claims and the drawings. It should be understood that the drawings are merely schematic and not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to denote the same or similar components.

[0138] There is provided a wet cleaning device comprising a cleaning head and an underpressure generator device. The cleaning head has at least one dirt inlet and a porous material covering the at least one dust inlet. The underpressure generator device comprises an underpressure generator configured to provide a flow inside the wet cleaning device for sucking a fluid through the porous material into the at least one dirt inlet. The underpressure generator device is configured to control the flow based on the pressure on the inside of the wet cleaning device between the porous material and the underpressure generator.

[0139] Figure 1 Shows a cleaning head 100 according to a non-limiting example. In particular, Figure 1 shows the underside 102 of the cleaning head 100. The underside 102 faces the surface to be cleaned using the cleaning head 100 ( Figure 1 not visible in

[0140] From Figure 1As can be clearly seen in the views shown, the cleaning head 100 includes at least one cleaning liquid outlet 104. The cleaning liquid can be delivered through each cleaning liquid outlet in, for example, the at least one cleaning liquid outlet 104. It should be noted that the at least one cleaning liquid outlet does not need to be provided on the lower side 102 of the cleaning head 100 and, alternatively, can be provided elsewhere in the cleaning head 100 as long as the cleaning liquid can be delivered via the (one or more) cleaning liquid outlets to reach the surface to be cleaned.

[0141] The cleaning liquid can include water or consist of water. Thus, the cleaning liquid can be an aqueous cleaning liquid. In some non-limiting examples, which will be discussed in more detail below, the cleaning liquid is an aqueous detergent solution.

[0142] In Figure 1 In the non-limiting example shown, the cleaning liquid outlets 104 are arranged in a row along the length 106 of the cleaning head 100. This can help the cleaning head 100 to wet the surface to be cleaned with the cleaning liquid along the length 106 of the cleaning head 100. Nevertheless, it should be noted that any suitable configuration or pattern of the cleaning liquid outlets 104 can be envisaged as long as other components capable of accommodating the cleaning head 100 are provided.

[0143] In Figure 1 In the specific example shown, the cleaning head 100 includes sixteen cleaning liquid outlets 104. It should be noted that more cleaning liquid outlets 104 can help to increase the evenness of wetting of the surface to be cleaned. However, any suitable number of cleaning liquid outlets 104 can be provided in the cleaning head 100, such as one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen, twenty or more.

[0144] In some embodiments, as Figure 1 shown, the cleaning head 100 includes a cleaning liquid distribution band 108. As shown, at least some or in this example all of the cleaning liquid outlets 104 can be included in the cleaning liquid distribution band 108.

[0145] Figure 2 There is provided a cross-sectional view of the cleaning liquid distribution band 108 included in the Figure 1 exemplary cleaning head 100 shown. In this non-limiting example, the cleaning liquid distribution band 108 includes a channel 110 which can be supplied with cleaning liquid, for example, via an inlet 112 from a suitable cleaning liquid reservoir ( Figure 2 not visible in the figure).

[0146] In Figure 2In the example shown, the inlet 112 is provided at or near the end of the cleaning liquid distribution strip 108. However, it is also conceivable that the inlet 112 is provided at a central position along the length of the cleaning liquid distribution strip 108. Alternatively or additionally, the cleaning liquid distribution strip 108 includes a plurality of inlets 112, such as a pair of inlets 112 provided at opposite ends of the cleaning liquid distribution strip 108.

[0147] The cleaning liquid can leave the cleaning liquid distribution strip 108 through an orifice that defines the cleaning liquid outlet 104 in the cleaning liquid distribution strip 108. Such an orifice can be sized such that when the channel 110 is being filled, the cleaning liquid, such as an aqueous cleaning liquid, is restricted from passing through the orifice due to the surface tension of the cleaning liquid, but once the channel 110 has been filled, the cleaning liquid is allowed to pass through all the orifices of the cleaning liquid distribution strip 108. This can cause the surface to be cleaned across the length 106 of the cleaning head 100 to be wetted relatively uniformly.

[0148] To this end, each cleaning liquid outlet 104 can have a diameter of, for example, less than 1 mm, such as in the range of 0.1 mm to 1 mm, preferably 0.1 mm to 0.8 mm, and most preferably 0.1 mm to 0.5 mm, such as approximately 0.3 mm.

[0149] The cleaning liquid distribution strip 108 can be formed of any suitable material, such as metal, metal alloy (such as stainless steel), and / or polymer. Forming the cleaning liquid distribution strip 108 from a polymer can make the cleaning liquid distribution strip 108 lighter and / or less expensive to manufacture.

[0150] Returning to Figure 1 , the cleaning head 100 further includes a porous material that includes a porous material layer 114 or, in some embodiments, consists of the porous material layer 114. Although not visible in Figure 1 , the cleaning head 100 has at least one dirt inlet. Each of the (multiple) dirt inlets is covered by the porous material layer 114.

[0151] The porous material layer 114 can be arranged between the (multiple) dirt inlets and the surface to be cleaned such that the dirt liquid on the surface to be cleaned is first transported into the pores of the porous material layer 114 and then enters the (multiple) dirt inlets from the porous material layer 114.

[0152] Figure 1 The view provided in

[0153] The porous material layer 114 is disposed at or near the lower side 102 of the cleaning head 100. More generally, the porous material, although not necessarily specifically the porous material layer 114 included in the porous material, can contact the surface to be cleaned and / or the liquid on the surface to be cleaned.

[0154] In a non-limiting example in which the porous material includes one or more additional porous material layers (not visible in Figure 1 ) disposed on the outer surface 116 of the porous material layer 114, the outer surface of the additional porous material layer that is furthest from at least one dirt inlet in the thickness direction of the porous material can contact the surface to be cleaned.

[0155] The porous material layer 114 covering each dirt inlet of the at least one dirt inlet can help maintain a negative pressure in the (multiple) dirt inlets in the case where a constant flow rate is or is not applied to the (multiple) dirt inlets, for example, by a negative pressure generator (such as a pump) fluidly connected to the dirt inlet.

[0156] The porous material layer 114 can include or be composed of, for example, a porous fabric and / or a porous foam. The porous fabric can be, for example, a microfiber fabric.

[0157] Similarly, each of the one or more additional porous material layers can include or be composed of a porous fabric (such as a microfiber fabric) and / or a porous foam.

[0158] As used herein, the term "microfiber fabric" refers to a fabric formed from synthetic fibers, which is formed from filaments having a fineness of less than 1 decitex.

[0159] Such a microfiber fabric can include, for example, polyester fibers, polyamide fibers, and combinations of polyester and polyamide fibers.

[0160] The microfiber fabric can be, for example, a microfiber chamois.

[0161] In other examples, the porous fabric is natural chamois, for example, made of chamois, deer skin, goat skin, or sheep skin.

[0162] The surface tension of the liquid retained in the pores of the porous material layer 114 can help maintain the negative pressure. This surface tension can be overcome at a point (or points) on the outer surface 116 of the porous material layer 114 in contact with the liquid, so that the liquid is transported through the porous material layer 114 in the direction of the (multiple) dirt inlets.

[0163] For example, a porous material including a microfiber fabric may be particularly prone to wear, and such wear may risk compromising the underpressure retention / liquid pick-up performance of the porous material. Accordingly, the porous material may include a plurality of layers of different colors that are gradually worn by using the cleaning head 100 such that the color of the porous material serves as a wear indicator.

[0164] In some embodiments, for example Figure 1 in the illustrated embodiment, the porous material and / or the porous material layer 114 included in the porous material is elongate and thus has a maximum dimension extending parallel to the length 106 of the cleaning head 100.

[0165] In Figure 1 the non-limiting example shown, the porous material layer 114 is located at different positions relative to the cleaning liquid outlet 104 along the width 118 of the cleaning head 100.

[0166] In some embodiments, such as Figure 1 shown, the cleaning head 100 includes a portion 120 for facing the surface to be cleaned. One or more cleaning liquid outlets 104 may be arranged to deliver cleaning liquid to the portion 120 of the cleaning head 100.

[0167] Although not visible in the Figure 1 view provided, the protruding element may be mounted adjacent to the portion 120, where the protruding element protrudes from the cleaning head 100 in the direction of the surface to be cleaned. The protruding element may be considered an element that is mounted separately in the cleaning head 100 relative to the portion 120.

[0168] Due to the protruding nature of the protruding element, the protruding element may have a limited contact with the surface to be cleaned. The protruding element may for example have a smaller contact area with the surface to be cleaned than the portion 120.

[0169] In at least some embodiments, the protruding element includes a porous material. Since the contact area between the porous material and the surface to be cleaned is limited, the movement resistance of the cleaning head 100 on the surface to be cleaned can be reduced. This will be described in further detail below with reference to Figure 31 Further details.

[0170] In some embodiments, the cleaning head 100 may swing in a first direction on the protruding element to bring the portion 120 into contact with the surface to be cleaned, and swing in a second direction opposite to the first direction on the protruding element to separate the portion 120 from the surface to be cleaned.

[0171] In such embodiments, the protruding element may be considered a rocker that allows the cleaning head 100 to swing onto the portion 120. To achieve such a swinging function, the contact of the protruding element with the surface to be cleaned is restricted.

[0172] In some embodiments, such as in Figure 3 the non - limiting example shown, the cleaning head 100 includes a portion 120 for facing the surface to be cleaned and an additional portion 122. In such an embodiment, the porous material layer 114 may be disposed between the portion 120 and the additional portion 122.

[0173] Although not visible in the Figure 3 views provided, when the cleaning head 100 includes the above - mentioned protruding element, the protruding element may be mounted between the portion 120 and the additional portion 122. Thus, the protruding element may be an element separately mounted relative to both the portion 120 and the additional portion 122. In this way, the cleaning head 100 can swing forward on the protruding element to bring the portion 120 into contact with the surface to be cleaned, and swing backward to bring the additional portion 122 into contact with the surface to be cleaned.

[0174] Regardless of whether the cleaning head 100 includes a protruding element, the (one or more) cleaning liquid outlets 104 may be arranged to deliver the cleaning liquid to the portion 120 and the additional portion 122 of the cleaning head 100.

[0175] In Figure 3 the non - limiting example shown, the cleaning head 100 includes a cleaning liquid distribution belt 108 and an additional cleaning liquid distribution belt 124. The orifices of the cleaning liquid distribution belt 108 define the cleaning liquid outlets 104 that deliver the cleaning liquid to the portion 120, as described above with respect to Figure 1 and Figure 2 The additional orifices of the additional cleaning liquid distribution belt 124 define the cleaning liquid outlets 104 that deliver the cleaning liquid to the additional portion 122.

[0176] Both the cleaning liquid distribution belt 108 and the additional cleaning liquid distribution belt 124 may extend parallel to the length 106 of the cleaning head 100, as Figure 3 shown.

[0177] In some embodiments, such as Figure 4 the embodiment shown, the cleaning head 100 includes cleaning liquid applicator materials 126, 128 adjacent to each of the at least one cleaning liquid outlet 104. The cleaning liquid applicator materials 126, 128 are arranged to apply the cleaning liquid to the surface to be cleaned. In other words, the cleaning liquid applicator materials 126, 128 can receive the cleaning liquid delivered from the (one or more) cleaning liquid outlets 104 and transfer the cleaning liquid to the surface to be cleaned.

[0178] The cleaning liquid applicator materials 126, 128 may include, for example, polyamide and / or polyester fibers.

[0179] Alternatively or additionally, the cleaning liquid applicator materials 126, 128 comprise a combination of thinner and thicker fibres.

[0180] The thinner fibres can be, for example, less than or equal to 1 dtex, and the thicker fibres can have a thickness greater than 0.01 mm, for example the thickness of the thicker fibres can be about 0.05 mm.

[0181] The thicker fibres, which can be made of polyamide or polyester, can contribute to reducing the friction between the cleaning liquid applicator materials 126, 128 and the surface to be cleaned, while the thinner fibres, which can be made of polyamide or polyester for example, can contribute to enhancing the dirt retention.

[0182] The thicker fibres can also provide elasticity to the cleaning liquid applicator materials 126, 128, thereby minimising the compression of the cleaning liquid applicator materials 126, 128.

[0183] The compression reduction ability of the thicker fibres is particularly useful in embodiments where the cleaning liquid applicator materials 126, 128 are included in the portion 120 adjacent to the projecting element rocker and / or the additional portion 122. This is because the minimised compression can help to ensure that a consistent degree of wobbling on the projecting element results in the cleaning liquid applicator materials 126, 128 contacting the surface to be cleaned during continued use of the cleaning head 100.

[0184] The thickness of the cleaning liquid applicator materials 126, 128 can alternatively or additionally be selected or restricted, for example taking into account the degree of protrusion of the projecting element relative to the portion 120 and / or the additional portion 122, in order to minimise the compression of the cleaning liquid applicator materials 126, 128 during use of the cleaning head 100.

[0185] In embodiments where the cleaning liquid applicator materials 126, 128 comprise a combination of thinner and thicker fibres, these fibres can be arranged relative to each other in any suitable manner. For example, the cleaning liquid applicator materials 126, 128 can comprise a thicker fibre band adjacent to a thinner fibre band. These bands can each extend along the length 106 of the cleaning head 100 such that the fibre thickness varies alternately in the width 118 direction. This configuration can help to reduce friction when the cleaning head 100 is moved in a direction parallel to the width 118 direction.

[0186] In embodiments where the cleaning liquid applicator materials 126, 128 comprise both polyamide and polyester fibres, these fibres can be arranged relative to each other in any suitable manner. For example, the cleaning liquid applicator materials 126, 128 can comprise a polyamide fibre band adjacent to a polyester fibre band. These bands can each extend along the length 106 of the cleaning head 100 such that the fibre type alternates in the width 118 direction.

[0187] The cleaning liquid applicator materials 126, 128 can, for example, include a backing layer that supports a material (such as a material containing polyamide and / or polyester fibers) in contact with the surface to be cleaned. The backing layer can be formed from any suitable backing fabric material (such as polyester).

[0188] Such a backing layer can be provided with tufts, for example, tufts formed from polyamide and / or polyester fibers. Such tufts can help the cleaning liquid applicator materials 126, 128 follow the contour of the surface to be cleaned and / or can help the cleaning liquid applicator materials 126, 128 retain dirt particles while also minimizing the risk of scratching the surface to be cleaned.

[0189] In some embodiments, the cleaning liquid applicator materials 126, 128 can be distinguished from the porous material (at least) by a backing layer (such as the backing layer supporting the tufts described above) that is included in the cleaning liquid applicator materials 126, 128 but not in the porous material.

[0190] In some non - limiting examples, the fibers constituting the cleaning liquid applicator materials 126, 128 are the same as the fibers constituting the porous material.

[0191] In an alternative example, one way in which the cleaning liquid applicator materials 126, 128 can be distinguished from the porous material is the fineness, such as the denier, of the threads and / or fibers of the respective materials (such as the threads and / or fibers of the respective materials in contact with the surface to be cleaned). For example, the fibers of the (multiple) porous material layers constituting the porous material can be finer than the fibers of the cleaning liquid applicator materials 126, 128. Alternatively or additionally, the threads of the (multiple) porous material layers constituting the porous material can be finer than the threads of the cleaning liquid applicator materials 126, 128.

[0192] The porous material can generally be denser than the cleaning liquid applicator materials 126, 128, for example, due to a tighter weave of the microfiber fabric.

[0193] In some embodiments, the cleaning liquid applicator materials 126, 128 include multiple layers of different colors that are gradually worn away by using the cleaning head 100, such that the color of the cleaning liquid applicator materials 126, 128 serves as a wear indicator.

[0194] In some embodiments, the cleaning liquid applicator materials 126, 128 may be separable from each of the at least one cleaning liquid outlet 104. This may enable the replacement of the cleaning liquid applicator materials 126, 128, e.g., once the cleaning liquid applicator materials 126, 128 have become excessively worn, and / or enable the cleaning liquid applicator materials 126, 128 to be cleaned between uses. For example, wear may be indicated by the colored layer including the cleaning liquid applicator materials 126, 128 described above.

[0195] The cleaning liquid applicator materials 126, 128 may be attached to the cleaning head 100 in any suitable manner, particularly to the underside 102 of the cleaning head 100 in the non - limiting example shown. Figures 1 to 4 As shown, the depicted cleaning head 100 includes at least one fastening member 130A, 130B, 132A, 132B, which in this example is in the form of a Velcro strip, that engages with the additional fastening member(s) (not visible) on the cleaning liquid applicator materials 126, 128. The additional fastening member(s) may be included, for example, in or attached to the aforementioned backing layer of the cleaning liquid applicator materials 126, 128.

[0196] Returning Figure 3 to, the depicted cleaning head 100 includes at least one fastening member 130A, 130B, 132A, 132B, which in this example is in the form of a Velcro strip, that engages with the additional fastening member(s) (not visible) on the cleaning liquid applicator materials 126, 128. The additional fastening member(s) may be included, for example, in or attached to the aforementioned backing layer of the cleaning liquid applicator materials 126, 128.

[0197] Alternative ways of attaching (e.g., detachably coupling) the cleaning liquid applicator materials 126, 128 to the cleaning head 100, particularly to at least one cleaning liquid outlet 104, may be envisaged, such as using ejectors, button - buttonhole arrangements, zippers, etc.

[0198] In some embodiments, as Figure 4 shown, the cleaning liquid applicator materials 126, 128 include a first applicator portion 126 and a second applicator portion 128, and a porous material layer 114 is disposed between the first applicator portion 126 and the second applicator portion 128.

[0199] When the first applicator portion 126 is included in the cleaning head 100, the first applicator portion 126 may be included in the aforementioned portion 120 of the cleaning head 100.

[0200] In embodiments where the cleaning liquid applicator material (e.g., the first applicator portion 126) is included in the portion 120, the portion may be adapted to contact the surface to be cleaned and assist in cleaning the surface to be cleaned, e.g., by assisting in applying the cleaning liquid to the surface to be cleaned.

[0201] However, it is also conceivable that the cleaning liquid applicator material is not included in the portion 120, for example if the cleaning head 100 is supplied without such cleaning liquid applicator material. In such a case, although the portion 120 may have a potentially smaller cleaning capacity compared to the case where the cleaning liquid applicator material (such as the first applicator portion 126) is included in the portion 120, the portion 120 is still adapted to contact the surface to be cleaned (the portion 120 can contact the surface to be cleaned without the need for the portion 120 to include the cleaning liquid applicator material).

[0202] The first applicator portion 126 may include the above-mentioned additional fastening member(s), which engage with the fastening member(s) 130A, 130B provided on the cleaning head 100 for bonding the first applicator portion 126 in the portion 120.

[0203] Similarly, when the second applicator portion 128 is included in the cleaning head 100, the second applicator portion 128 may be included in the above-mentioned additional portion 122 of the cleaning head 100.

[0204] In such an embodiment, the second applicator portion 128 may include the above-mentioned additional fastening member(s), which engage with the fastening member(s) 132A, 132B provided on the cleaning head 100 for bonding the second applicator portion 128 in the additional portion 122.

[0205] In some embodiments, at least one cleaning liquid outlet 104 includes at least a pair of cleaning liquid outlets 104, and the porous material layer 114 is disposed between each pair of cleaning liquid outlets 104.

[0206] In embodiments where the cleaning liquid applicator materials 126, 128 include the first applicator portion 126 and the second applicator portion 128, the first applicator portion 126 may be adjacent to one of the cleaning liquid outlets of the pair of cleaning liquid outlets 104, while the second applicator portion 128 is adjacent to the other cleaning liquid outlet of the pair of cleaning liquid outlets 104. In Figure 3 and Figure 4 such an example is shown.

[0207] In at least some embodiments, the porous material (although not necessarily specifically the porous material layer 114 included in the porous material) contacts the cleaning liquid applicator fabrics 126, 128.

[0208] By contacting the cleaning liquid applicator materials 126, 128 with a porous material, some of the cleaning liquid can be transferred from the cleaning liquid applicator materials 126, 128 to the porous material and into the (multiple) dirt inlets. This configuration can help prevent an excessive volume of cleaning liquid from accumulating in the cleaning liquid applicator materials 126, 128 and, thus, can help minimize overwetting of the surface to be cleaned, e.g., by dripping the cleaning liquid from the cleaning liquid applicator materials onto the surface to be cleaned. Alternatively or additionally, by contacting the cleaning liquid applicator materials 126, 128 with a porous material, the cleaning liquid in the latter can be used to effectively flush the porous material covering the (multiple) dirt inlets.

[0209] In a non-limiting example, the porous material layer 114 contacts the cleaning liquid applicator materials 126, 128. In an example where the porous material includes one or more additional porous material layers disposed on the outer surface 116 of the porous material layer 114 (not visible in Figure 3 and Figure 4 ), the porous material layer 114 and / or the (multiple) additional porous material layers can contact the cleaning liquid applicator materials 126, 128.

[0210] Although the porous material contacts the cleaning liquid applicator materials 126, 128, these materials can also be arranged to contact the surface to be cleaned. This can be achieved in any suitable manner. In some embodiments, as Figure 3 and Figure 4 shown, the edge portion 134 of the porous material abuts the opposite edge portions 136 of the cleaning liquid applicator materials 126, 128. Thus, the cleaning liquid can first be delivered into the cleaning liquid applicator materials 126, 128 and only subsequently be delivered from the cleaning liquid applicator materials 126, 128 to the porous material via the abutting edge portions 134, 136 of the respective materials. This can provide enhanced control over the humidity of the cleaning liquid applicator materials 126, 128.

[0211] Alternatively or additionally, the cleaning liquid applicator materials 126, 128 can be deformable to bring at least a portion of the cleaning liquid applicator materials 126, 128 into contact with the porous material.

[0212] By making the cleaning liquid applicator materials 126, 128 deformable so that at least a portion of the cleaning liquid applicator materials 126, 128 contacts the porous material, some cleaning liquid can be transferred from the cleaning liquid applicator materials 126, 128 to the porous material in a particularly controlled manner. In this way, over-wetting of the surface to be cleaned can be minimized, for example by dripping the cleaning liquid from the cleaning liquid applicator materials 126, 128 onto the surface to be cleaned. Alternatively or additionally, by deforming the cleaning liquid applicator materials 126, 128 such that at least a portion of the cleaning liquid applicator materials 126, 128 contacts the porous material, the cleaning liquid in the latter can be used to effectively rinse the porous material.

[0213] In at least some embodiments, the cleaning liquid applicator materials 126, 128 are configured to deform when contacting the surface to be cleaned and / or when wetted by a liquid (such as water).

[0214] Such wetting can be the result of the delivery of the cleaning liquid from the (one or more) cleaning liquid outlets to the cleaning liquid applicator materials 126, 128 and / or due to the presence of liquid on the surface to be cleaned.

[0215] In a non-limiting example, the cleaning liquid applicator materials 126, 128 include tufts formed by fibers and a backing layer that supports the tufts. Such tufts can be deformed to contact the porous material, for example when contacting the surface to be cleaned and / or when wetted by a liquid such as water.

[0216] While the tufts remain in contact with the porous material, the cleaning liquid can be transferred from the cleaning liquid applicator materials 126, 128 to the porous material via the tufts.

[0217] In some embodiments, the cleaning liquid applicator material is deformable so that an edge portion 136 of the cleaning liquid applicator materials 126, 128 contacts the porous material, for example contacts an edge portion 134 of the porous material.

[0218] For example, when the cleaning liquid applicator materials 126, 128 are deformed so that an edge portion 136 of the cleaning liquid applicator materials 126, 128 contacts the porous material, the edge portion 136 of the cleaning liquid applicator materials 126, 128 can abut the (opposite) edge portion 134 of the porous material.

[0219] In some embodiments, the edge portions 136 of the cleaning liquid applicator materials 126, 128 are arranged to contact the surface to be cleaned at least when the cleaning liquid applicator materials 126, 128 are deformed such that the edge portions 136 of the cleaning liquid applicator materials 126, 128 contact the porous material. Thus, the humidity of the cleaning liquid applicator materials 126, 128 can be controlled where the cleaning liquid applicator materials 126, 128 contact the surface to be cleaned, thereby minimizing the risk of over-wetting the surface to be cleaned.

[0220] In a non-limiting example, the cleaning liquid applicator materials 126, 128 can be deformed such that at least a portion of the cleaning liquid applicator materials 126, 128 contacts the porous material layer 114 of the porous material. In an example where the porous material includes one or more additional porous material layers, the deformation of the cleaning liquid applicator materials 126, 128 causes at least a portion (e.g., edge portion 136) of the cleaning liquid applicator materials 126, 128 to contact the porous material layer 114 and / or the additional porous material layer(s).

[0221] In embodiments where the cleaning head 100 includes the above-described projecting element, the adjacent opposite edge portions 134, 136 of the porous material and the cleaning liquid applicator materials 126, 128 are preferably positioned between the projecting element and the portion 120. In this way, for example, by swinging the cleaning head 100 via the projecting element, the excess cleaning liquid extruded from between the projecting element and the cleaning liquid applicator materials 126, 128 can be effectively transported via the porous material into the dirt inlet(s).

[0222] It should be noted that the contact between the porous material and the cleaning liquid applicator materials 126, 128 can be provided on the surface contact side of the materials to be cleaned. This can help to prevent the cleaning liquid from directly entering the porous material and inappropriately wetting the cleaning liquid applicator materials 126, 128 or flushing the porous material.

[0223] In some embodiments, the cleaning liquid applicator materials 126, 128 can be deformed such that at least a portion of the cleaning liquid applicator materials 126, 128 contacts the porous material between the projecting element and the portion 120.

[0224] Thus, for example, the excess cleaning liquid extruded from between the projecting element and the cleaning liquid applicator materials due to the swinging of the cleaning head 100 on the projecting element can be effectively transported via the porous material into the dirt inlet(s).

[0225] In embodiments where the cleaning liquid applicator materials 126, 128 include the first applicator portion 126 and the second applicator portion 128 described above, the opposing edge portions 136 of the cleaning liquid applicator materials 126, 128 may be included in the first applicator portion 126, as Figure 4 shown. Additionally, additional edge portions 138 of the porous material may abut additional opposing edge portions 140 of the second applicator portion 128. Examples of this are described in Figure 3 and Figure 4 .

[0226] When the above-described protruding element is disposed between the portion 120 and the additional portion 122, the adjacent opposing edge portions 134, 136 of the porous material and the first applicator portion 126 are preferably positioned between the protruding element and the portion 120, and the adjacent opposing additional edge portions 138, 140 of the porous material and the second applicator portion 128 are preferably positioned between the protruding element and the additional portion 122.

[0227] In this way, for example, the excess cleaning liquid extruded from the cleaning liquid applicator materials 126, 128 between the protruding element and the first and second cleaning liquid applicator portions 126, 128 caused by swinging the cleaning head 100 forward and backward respectively can be effectively transported via the porous material to the (multiple) dirt inlets.

[0228] The opposing edge portions 136 and / or the additional opposing edge portions 140 (when present) of the cleaning liquid applicator materials 126, 128 may be arranged, for example, to contact the surface to be cleaned. Thus, the humidity of the cleaning liquid applicator materials 126, 128 can be controlled at the location where the cleaning liquid applicator materials 126, 128 contact the surface to be cleaned, thereby minimizing the risk of over-wetting the surface to be cleaned.

[0229] In some embodiments, the first applicator portion 126 may be deformable to bring at least a portion of the first applicator portion 126 into contact with the porous material between the portion 120 and the protruding element, and / or the second applicator portion 128 may be deformable to bring at least a portion of the second applicator portion 128 into contact with the porous material between the additional portion 122 and the protruding element.

[0230] Figure 5A A plan view showing the porous material layer 114 and at least one dirt inlet 142A, 142B of the exemplary cleaning head 100 is provided. Figure 5B There is provided Figure 5A a schematic cross-sectional view of the porous material layer 114 and at least one dirt inlet 142A, 142B shown in

[0231] In some embodiments, as Figure 5Aand Figure 5B As shown, each of the at least one dirt inlet 142A, 142B is defined by an opening of one or more tubes 144A, 144B that are fluidly connected or can be fluidly connected to a negative pressure generator (not visible in Figure 5A and Figure 5B ).

[0232] In the non - limiting example shown in Figure 5A and Figure 5B , the cleaning head 100 includes a pair of dirt inlets 142A, 142B, but any suitable number of dirt inlets 142A, 142B can be contemplated, such as one, two, three, four, five, six or more.

[0233] When multiple dirt inlets 142A, 142B are included in the cleaning head 100, they can, for example, have the same size as each other.

[0234] Alternatively or additionally, when multiple (e.g., a pair of) dirt inlets 142A, 142B are employed, the dirt inlets 142A, 142B can be spaced apart along the length 106 of the cleaning head 100 so as to provide relatively uniform suction along the length 106 of the cleaning head 100. For example, the distance along the length 106 between the center position of the cleaning head 100 and the center of the dirt inlet 142A can be the same as or substantially the same as the distance along the length 106 between the center position and the center of the dirt inlet 142B.

[0235] If a single dirt inlet is employed, this can be provided at the center position of the cleaning head 100 to provide a relatively symmetric suction profile along the length 106 of the cleaning head 100.

[0236] More generally, the liquid pickup region PR of the porous material layer 114 is defined by a sealed attachment of the porous material layer 114 around each of the at least one dirt inlet 142A, 142B, for example.

[0237] Such a sealed attachment can help maintain a negative pressure in the covered dirt inlets 142A, 142B, as leakage losses of negative pressure through the gap between the dirt inlets 142A, 142B and the porous material layer 114 are minimized or prevented.

[0238] The sealed attachment can be achieved in any suitable manner, such as by gluing or welding the porous material layer 114 around each of the at least one dirt inlet 142A, 142B, for example, gluing and / or welding the porous material layer 114 around the opening(s) that define the (multiple) dirt inlets 142A, 142B to the above - mentioned (multiple) tubes 144A, 144B.

[0239] In particular, the porous material layer 114 is sealingly attached to the (multiple) dirt inlets 142A, 142B by heat sealing (such as ultrasonic welding). It has been found that this provides a particularly airtight seal in a direct manner, which helps to maintain the underpressure in the (multiple) dirt inlets 142A, 142B.

[0240] Referring Figure 5B , Figure 6A and Figure 6B , a non-limiting example of the sealing attachment of the porous material layer 114 to the dirt inlets 142A, 142B is achieved by the cleaning head 100, which includes an impermeable portion 146 that is sealed to the porous material layer 114 (such as to the inner surface 148 of the porous material layer 114) and surrounds the dirt inlets 142A, 142B, whereby the dirt inlets 142A, 142B are exposed to a sealed cavity 150 between the porous material layer 114 and the impermeable portion 146.

[0241] The impermeable portion 146 can for example include a polymer film, such as a thermoplastic film, or consist of a polymer film. Various alternative sealing arrangements are described below, some of which do not include such a polymer film.

[0242] In Figure 6A and Figure 6B the non-limiting example shown, a seal 152, formed for example by adhesion and / or welding of the impermeable portion 146 (such as a polymer film), extends around the perimeter of the porous material layer 114 and around the dirt inlets 142A, 142B.

[0243] In at least some embodiments, such as Figure 7A and Figure 7B the embodiments shown, the liquid pickup area PR is arranged relative to at least one cleaning liquid outlet 104 to allow the cleaning liquid to bypass, for example, pass around the perimeter of the liquid pickup area PR, to reach or at least be directed towards the surface to be cleaned.

[0244] This can enable more efficient use of the cleaning liquid. This is because the cleaning liquid has a greater chance of reaching the surface to be cleaned, for example, through the above-described cleaning liquid applicator materials 126, 128 (when included in the cleaning head 100).

[0245] In other examples, the porous material can be at least partially attached around the (multiple) dirt inlets 142A, 142B by being adsorbed against the (multiple) dirt inlets 142A, 142B by the flow provided by an underpressure generator, for example against the cleaning head 100 or a component of the cleaning head 100.

[0246] In some embodiments, the cleaning head 100 includes a liquid delivery support structure 154 within the cavity 150, the liquid delivery support structure 154 being arranged to provide one or more flow paths between the pores of the porous material layer 114, particularly the porous material layer 114, and at least one dirt inlet 142A, 142B in the liquid pickup region PR.

[0247] The porous material layer 114 (such as a microfiber fabric) and / or the impermeable portion 146 (such as a polymer film) may be flexible such that the underpressure can cause the porous material layer 114 and the impermeable portion 146 to be stretched towards each other. This may risk restricting the flow of liquid from the porous material layer 114 to at least one dirt inlet 142A, 142B. Although the porous material layer 114 and the impermeable portion 146 are stretched towards each other, the liquid delivery support structure 154 can help ensure that liquid can still be delivered from the porous material layer 114, particularly the pores of the porous material layer 114, to at least one dirt inlet 142A, 142B.

[0248] The liquid delivery support structure 154 can be implemented in any suitable manner. In Figure 7A and Figure 7B the non-limiting example shown, the liquid delivery support structure 154 includes or is defined by one or more mesh layers. In such an example, the above one or more flow paths can be provided by the spaces between the elements making up the (multiple) mesh layers. Alternative examples of the liquid delivery support structure 154 will be described below.

[0249] As described above, in some embodiments, in addition to the porous material layer 114, the porous material may include one or more additional porous material layers 156, 158. Examples thereof are described in Figure 8 and Figure 9 herein.

[0250] At this time, it should be noted that when the porous material is dry, the porous material can be regarded as being in an "air delivery state" in which air is delivered through each dry pore of the porous material. The "liquid delivery state" corresponds to liquid (such as water) being delivered through the (wetted) pores of the porous material. When no more liquid is supplied to the (multiple) pores, a "fluid blockage state" can be adopted. The "fluid blockage state" corresponds to a state in which the surface tension of the (residual) liquid retained in the wetted (multiple) pores of the porous material prevents fluid from being delivered through the (multiple) pores. In the latter state, a surface or barrier is generated at the boundary between air and liquid (such as water). This barrier can help maintain the above underpressure in the (multiple) dirt inlets 142A, 142B. The pressure required to "break" this barrier can be referred to as the "rupture pressure".

[0251] It should be noted that a woven porous fabric with a finer weave may have smaller pores, such as micropores, resulting in a higher burst pressure. However, there may be limitations on how to manufacture small pores using weaving techniques. At the same time, it is possible that certain fibers, such as those selected due to their favorable cleaning and / or wear properties, can only be woven to provide a more open structure that is not suitable for maintaining a sufficient underpressure in the (multiple) dirt inlets 142A, 142B.

[0252] However, the "burst pressure" can be adjusted in various ways. In Figure 8 the non-limiting example shown, the porous material includes a porous material layer 114 and an additional first porous material layer 156 or is defined by the porous material layer 114 and the additional first porous material layer 156.

[0253] For example, the porous material layer 114 is a microfiber fabric and the additional first porous material layer 156 is a microfiber fabric.

[0254] By including a stacked porous material of the porous material layers 114, 156 in this way, the burst pressure can be increased, for example, as compared to a situation where the porous material consists only of the porous material layer 114.

[0255] Without wishing to be bound by any particular theory, it is believed that this effect stems from changes in pore size and shape, such as statistical variations. For example, a microfiber fabric can be made from many fibers and yarns that are woven together into a fabric sheet. Thus, pores, such as micropores, can be created between the fibers and yarns, and the pore sizes present in the fabric are not precisely fixed to one size and shape but vary statistically.

[0256] A single porous material layer 114 can include a few relatively large pores (for which the surface tension of the residual liquid is small), such that these relatively large pores contribute to the lower burst pressure of the single porous material layer 114. By stacking an additional porous material layer 156 on the porous material layer 114, the likelihood that the above-mentioned few relatively large pores of the porous material layer 114 align / communicate with the relatively large pores included in the additional porous material layer 156 can be relatively small. Therefore, the stacking of the porous material layers 114, 156 can contribute to increasing the burst pressure of the porous material.

[0257] Although in Figure 8 the non-limiting example shown, the porous material is formed by the porous material layer 114 and an additional first porous material layer 156, more than one additional porous material layer 156 can be included in the porous material, for example, to further increase the burst pressure. In Figure 9In the non-limiting examples shown, the porous material includes a porous material layer 114, an additional first porous material layer 156, and an additional second porous material layer 158, or is defined by a porous material layer 114, an additional first porous material layer 156, and an additional second porous material layer 158.

[0258] For example, the porous material layer 114 is a microfiber fabric, the additional first porous material layer 156 is a microfiber fabric, and the additional second porous material layer 158 is a microfiber fabric.

[0259] The porous material layers 114, 156, 158 of the porous material may or may not adhere to each other. In a non-limiting example where the porous material layers 114, 156, 158 adhere to each other via a suitable adhesive applied between the porous material layers, this can help further increase the burst pressure of the porous material.

[0260] Without wishing to be bound by any particular theory, this is thought to be due to the adhesive hindering the horizontal fluid transport between the adhering porous material layers. Turning to Figure 10 , the fluid transport through the pores 160A, 160B of the porous material layer 114 is schematically depicted in the upper left grid, and the horizontal fluid transport between the non-adhering porous material layer 114 and the pores 162A of the additional first porous material layer 156 is schematically depicted in the lower left grid. Comparing the latter with Figure 10 the right grid, it is evident that the adhesive 164 between the porous material layer 114 and the additional first porous material layer 156 restricts or prevents the horizontal fluid transport between the pores 160A of the porous material layer and the pores 162A, 162B of the additional first porous material layer 156.

[0261] Any suitable adhesive 164 can be used to bond the porous material layers 114, 156, 158 to each other, such as a heat-activated fabric glue. Commercially available examples of heat-activated fabric glue are

[0262] The advantage that the porous material layers 114, 156, 158 of the porous material do not adhere to each other can be that the resistance to the transport of liquid through the porous material can be reduced, for example, due to allowing the horizontal transport of liquid between the porous material layers 114, 156, 158, or at least less restricting the horizontal transport of liquid between the porous material layers 114, 156, 158 compared to the case where the adhesive 164 is present between the porous material layers 114, 156, 158.

[0263] As an alternative or addition to the porous material layer 114 that also includes one or more additional porous material layers 156, 158, the porous material layer 114 (e.g., microfiber fabric) can be subjected to a densification process, such as by ultrasonic welding. This helps to increase the burst pressure of the porous material layer 114.

[0264] In an exemplary densification process, the porous material layer 114 (e.g., a porous fabric, such as a microfiber fabric) is placed (e.g., compressed) between two elements (e.g., rollers), and vibrations of relatively high frequency (e.g., about 40 kHz) are emitted into the porous material layer 114.

[0265] Such vibrations may cause the fibers of the porous fabric (e.g., microfiber fabric) to move and rub against each other, generating heat, which may cause individual fibers to be welded together. This welding can be controlled to provide a denser porous structure rather than a dense solid block. Since the process can be carried out while the porous fabric is in a compressed state, the density of the fabric can be increased, thereby increasing the burst pressure.

[0266] When one or more additional porous material layers 156, 158 are included in the porous material, such a densification process can alternatively or additionally be used to densify one or more of the additional porous material layers 156, 158.

[0267] Figure 11 An exemplary test device 166 for testing the burst pressure characteristics of a porous material 168 is schematically shown. The porous material 168 is clamped between a clamping member 170 and a substrate 172. The clamping member 170 defines a hole for a bolt 174, and the bolt 174 is received in a threaded hole in the substrate 172. Rotating the bolt 174 in an appropriate direction can clamp / loosen the porous material 168.

[0268] In this specific example, the clamping member 170 is an aluminum ring with a thickness of 10 mm, and the substrate 172 is made of poly(methyl methacrylate) with a thickness of 10 mm. The sample of the porous material is a disk with a diameter of 140 mm. Eight bolts 174 are used to fix the sample.

[0269] The dirt inlet 142A in the test device 166 is defined by an opening of a delivery conduit 176 provided in the substrate 172. In the cavity between the porous material 168 and the dirt inlet 142A, the above-described liquid delivery support structure 154 is provided, and in this case, the liquid delivery support structure 154 is in the form of a net with a diameter of 80 mm.

[0270] The test device 166 includes a vacuum generator 178 for generating a vacuum in the dirt inlet 142A, and a pressure sensor 180, such as a pressure gauge, provided to measure the pressure in the dirt inlet 142A.

[0271] In this specific example, the pressure sensor 180 includes a manometer combined with a data acquisition unit ( 2) to be able to monitor the pressure as a function of time.

[0272] In this specific example, the underpressure generator 178 is in the form of a peristaltic pump or an injection pump, such as a 250 mL injection pump. The peristaltic pump can provide a pulsed water flow. It has been found that the injection pump allows for more precise measurements than the peristaltic pump.

[0273] The test device 166 also includes a pressure line filter 182 in the form of a chamber, which is arranged to prevent liquid from entering the pressure sensor line 184 connecting the pressure line filter 182 and the pressure sensor 180. Downstream of the pressure line filter 182 and the pump 178 is a collection reservoir 186 for collecting the liquid pumped through the porous material 168.

[0274] The test procedure includes clamping a sample of the porous material 168 between the clamping member 170 and the substrate 172, and then setting the pump 178 to deliver a flow rate of 100 cm 3 / min. The pressure line filter 182 is checked to ensure that it is empty, and the manometer of the pressure sensor 180 is zeroed and reconnected before each measurement. Then 25 cm 3 of water is poured onto the sample of the porous material 168, leaving a water layer with a depth of approximately 4 mm on the porous material. Then a flushing run is carried out by starting the pump 178 so that the water is suctioned through the sample of the porous material 168. After the flushing run, the pump 178 is stopped and 25 cm 3 of water is poured onto the sample of the porous material 168, and a measurement run is carried out by triggering the data acquisition unit to start data acquisition and starting the pump 178.

[0275] Figure 12 A typical graph of underpressure versus time from the data acquisition, as well as a schematic diagram of the porous material 168, are provided in

[0276] The control equation describing the "liquid delivery state" 188 can be the following Poiseuille equation:

[0277]

[0278] where ΔP is the pressure difference across the aperture 192; η is the dynamic viscosity of the liquid; L is the length of the aperture 192; φ is the volumetric flow rate; and r is the radius of the aperture 192.

[0279] For example, assuming an aperture diameter of 20 μm, the aperture extending through a porous material 168 having a thickness of 0.8 mm, an estimated volumetric flow rate of about 4.96*10 -14 m 3 / s per aperture 192 (from a typical fluid flow rate of 100 cm 3 / min), and η 水 is 1*10 -3 Pa·s, ΔP = 10.1 Pa.

[0280] After the "liquid delivery state" 188, an intermediate state 194 is adopted, in which almost all of the liquid 190 has been removed from the surface of the sample of the porous material 168, such that most of the apertures are in the above-described "fluid blockage state", in which the surface tension of the (residual) liquid 190 remaining in the wetted (multiple) apertures of the porous material 168 prevents air 196 from being delivered through the apertures 192. In the intermediate state 194, a decreasing number of apertures 192 may be in the "liquid delivery state". The "fluid blockage state" allows a significantly higher underpressure, and thus the underpressure increases relatively rapidly during the intermediate state 194, as shown in the figure.

[0281] The control equation describing the "fluid blockage state" may be the following droplet dP equation:

[0282]

[0283] where Pi is the internal pressure, P O is the external pressure, R is the radius of the fluid droplet, as Figure 12 schematically shown. T is the surface tension.

[0284] For example, assuming for a typical 20-μm diameter aperture 192, R is 10 μm, and T 水 is 0.073 N / m, P i −P O = ΔP = 14600 Pa.

[0285] When a detergent is added to water, this ΔP can increase to 18000 Pa. When the detergent is added, the surface tension of the water decreases (T 肥皂水 is 0.045 N / m), and at this time two surfaces are created in the bubble on the aperture 192: the inside and the outside of the bubble. Therefore, the bursting pressure in the case where the detergent is added to the water can be approximately twice the bursting pressure of a single layer surface:

[0286]

[0287] After the intermediate state 194, the end state 198 is adopted, in which all free water has been removed from the surface of the porous material 168 and all the pores 192 are initially in a "fluid blockage state". Since the pump 178 continues to pump water through the porous material 168, the underpressure is increased, which may cause some fluid blocks to rupture, enabling air 196 to be transported through the corresponding pores 192 in an "air transport state". The associated air entry can reach equilibrium in the end state 198, where the applied flow results in an underpressure that no longer causes fluid block rupture. The latter corresponds to the "rupture pressure" of the porous material 168 under study.

[0288] The governing equation describing the "air transport state" can be the Poiseuille equation provided above for the "liquid transport state". For example, assuming a pore diameter of 20 μm, the pore extending through the porous material 168 with a thickness of 0.8 mm, the estimated volumetric flow rate is about 4.96*10 -14 m 3 / s per pore 192 (from a typical fluid flow rate of 100 cm 3 / min), and η 空气 is 18.1*10 -6 Pa·s, ΔP = 0.18 Pa.

[0289] Generally, compared with the pressure difference generated by surface tension (e.g., 14600 Pa), both the air transport pressure (e.g., 0.18 Pa) and the water transport pressure (e.g., 10.1 Pa) can be significantly smaller, e.g., negligible.

[0290] Figure 13 Several pressure-time graphs of the porous material 168 tested using the above test device 166 and test procedure are provided. Curve 200 is for the porous material 168 with only the porous material layer 114; curve 202 is for the porous material 168 with the porous material layer 114 and an additional first porous material layer 156; curve 204 is for the porous material 168 with the porous material layer 114, an additional first porous material layer 156 and an additional second porous material layer 158; and curve 206 is for the porous material 168 with the porous material layer 114 and three additional porous material layers. These data indicate that, as described above, including more stacked porous material layers in the porous material 168 increases the rupture pressure.

[0291] Furthermore, each curve in the group of curves 202, 204, and 206 is for the porous material 168 where the porous material layers are either adhered or not adhered to each other. It is observed that using an adhesive to adhere the porous material layers to each other further increases the rupture pressure, as described above.

[0292] Figure 14Schematically shows the above-mentioned "liquid delivery state" 188, where in a) the liquid is sucked through all the holes 192, in b) the end of the liquid delivery state 188, in c) the intermediate state 194, and in d) the final state 198. The porous material 168 is shown in Figure 14 covering the (multiple) dirt inlets 142A, 142B connected to the underpressure generator 178 (such as a pump).

[0293] The porous material 168 has holes 192, such as micropores, each with a different bursting pressure. The latter is represented by the numbers provided below each hole 192 in Figure 14 For simplicity, each number is rounded to a single digit.

[0294] When the underpressure generator 178 (such as a pump) is started, all the liquid (such as water) is drawn out of the floor, and the required pressure is the water delivery pressure, which is set to "1" in this example. The underpressure in the dirt inlet 142A, and correspondingly the underpressure in the cavity 150 behind the porous material 168 in this example, is "1". Therefore, Figure 14 a) in schematically represents the "liquid delivery state" 188, and b) shows the end of the "liquid delivery state" 188. In b), the point where the underpressure starts to rise is reached.

[0295] When all the liquid, such as water, has been removed from the floor, all the holes 192 can be blocked by the surface tension of the residual liquid therein. In the non-limiting example shown, the underpressure generator 178 is a fixed-flow pump, so continuous operation of the pump can increase the underpressure. At a certain point, the underpressure in the dirt inlet 142A behind the porous material 168 can rise to the level of the bursting pressure of the weakest hole 192, such as "4", and the bursting pressure of the hole will be exceeded, and air can start to be delivered through it. Since the pressure in the dirt inlet 142A behind the porous material 168 may already be significant when these first holes 192 "burst", the air delivered through these holes 192 at this point may be significant. Therefore, Figure 14 step c) in can be regarded as schematically representing the intermediate state 194.

[0296] In the intermediate state 194, some of the holes 192 may be blocked, while other holes 192 are still delivering liquid from other areas (away from the (multiple) dirt inlets 142A), so more underpressure is generated near the (multiple) dirt inlets 142A. This can cause the underpressure to rise relatively slowly until all the free liquid disappears. This may all be affected by the pump speed, and in at least some examples, the characteristics of the liquid delivery support structure 154, together with the flexibility of all the components, deform when underpressure is applied.

[0297] For simplicity of explanation, if the flow rate is set to 100 cm 3 / min, ignoring the flow resistance between the porous material and the pump, and all components are infinitely rigid, then the intermediate state 194 can be Figure 12 the vertical line in, digitally moving from the "liquid delivery state" 188 to the end state 198.

[0298] This process can continue until the air delivered is equal to the pumping rate in this example, and the underpressure in the dirty inlet 142A behind the porous material 168 is lower than the bursting pressure of the remaining "unburst" holes 192 with the lowest bursting pressure. Thus, Figure 14 step d) in can be regarded as schematically representing the above-mentioned end state 198.

[0299] It should be noted that the pressure measured in the test device 166 can define the bursting pressure of the porous material 168. Different flow rates have been tested, such as 150 cm 3 / min, but the same bursting pressure is shown, noting that more holes 192 can "burst" to compensate for the increased flow.

[0300] The pore size (in other words, the pore diameter) of the holes 192 of the porous material 168 can be selected in order to balance the relatively high underpressure with the relatively low liquid delivery resistance / liquid delivery pressure of the porous material 168.

[0301] Smaller holes 192 can increase the underpressure generated in the dirty inlet 142A, for example, by using a relatively low-power underpressure generator 178 (such as a pump). A denser porous material 168 with smaller holes 192 can generate a higher bursting pressure. Also, to study the lower limit of the pore size, the above-mentioned test device 166 and test procedure were used for the study, and the test procedure used beer filters specified according to the particle sizes they can retain as the porous material 168: 0.25 μm, 3 μm, 10 μm, and 25 μm filters were tested. For this experiment, it was assumed that the latter beer filter specification was the same as the "pore size / diameter".

[0302] Referring to Figure 15 , curve 208 is for the 0.25 μm filter; curve 210 is for the 3 μm filter; curve 212 is for the 10 μm filter; curve 214 is for the 25 μm filter; curve 216 is for the reference microfiber fabric.

[0303] From Figure 15 it can be seen that the pore size / diameter of the porous material 168 has a significant impact on the performance. Based on the results, it is estimated that, considering the underpressure, an average pore diameter / diameter of 40 μm of the porous material 168 (for example, corresponding to a 40 μm beer filter) may correspond to the maximum value.

[0304] Based on considerations of liquid delivery pressure, the average 0.25 μm pore diameter / diameter of the porous material 168 (e.g., equivalent to a 0.25 μm beer filter) can correspond to a minimum value.

[0305] From Figure 15 It is evident that a 0.25 μm filter can result in a significantly higher water delivery pressure than a 3 μm filter. In the case of a 0.25 μm filter, the underpressure may rise to approximately 23000 Pa during water delivery. Additionally, for a 0.25 μm filter, the time to reach a dry state may be significantly longer, meaning that significantly more time may be spent delivering liquid / water from the surface to be cleaned.

[0306] In a non - limiting example, an average pore size / diameter of approximately 3 μm (e.g., equivalent to a 3 μm beer filter) of the porous material 168 can provide a favorable balance of properties.

[0307] Figure 15 There is shown to be a limited difference between the liquid / water delivery pressure and the burst pressure of the porous material 168. Relatively small pores 192 can lead to an increase in the burst pressure, e.g., up to 39000 Pa in the case of a 0.25 μm filter, but can also lead to an increase in the water / liquid delivery pressure, e.g., up to 33000 Pa in the case of a 0.25 μm filter. It should be noted that the difference between the water delivery pressure and the burst pressure is similar to that of the reference microfiber fabric (1000 Pa water delivery pressure; 7000 Pa burst pressure).

[0308] Bacteria tend to be characterized by having a relatively small size. For example, Escherichia coli cells are approximately 2 μm long and 0.5 μm in diameter.

[0309] Therefore, a porous material 168 with pore sizes greater than 2 μm can allow such bacteria to pass through. In this way, bacteria can be removed from the surface to be cleaned.

[0310] Depending on the porous material 168 selected, up to 99.9% of the bacteria can be drawn through the porous material 168 from the surface to be cleaned.

[0311] In some embodiments, the porous material 168 is defined by one or more layers of microfiber fabric, the pores of which have a pore size / diameter in the range of 0.25 μm to 40 μm (e.g., equivalent to a 0.25 μm to 40 μm beer filter).

[0312] For example, such a porous material 168 (defined by one or more layers of microfiber fabric) may have a pore size / diameter distribution in the range of 0.25 μm to 40 μm as described above, and an average pore size of 20 μm to 40 μm, for example, about 35 μm. Since the size of the pores is significantly larger than the size of bacteria, the bacteria can pass through the porous material 168, thereby being removed from the surface to be cleaned.

[0313] While the above description focuses on the working principle of the porous material 168, it should be noted that the porous material 168 can be in contact with the surface to be cleaned and move on the surface to be cleaned at a certain speed. This is Figure 16 schematically shown in Figure 16 which shows an exemplary cleaning head 100 that includes a dirt inlet 142A covered with the porous material 168 on the surface 218 to be cleaned. In this non-limiting example, the surface 218 to be cleaned is the surface of a floor 220, and there is a liquid layer 222, such as water, between the surface 218 to be cleaned and the porous material 168. A negative pressure generator 178, such as a pump, is used to suck fluid through the pores 192 of the porous material 168 in the direction of arrow 224. Arrow 226 represents the internal negative pressure that pulls the liquid towards the dirt inlet 142A. Arrow 228 represents the speed of the cleaning head 100.

[0314] Figure 16 The velocity distribution 234 in the fluid layer 222 is schematically shown. Arrow 230 represents the fluid shear force on the porous material 168 generated by the velocity distribution 234 in the fluid layer 222. Arrow 232 represents the shear force that pulls the water towards the floor 220.

[0315] This behavior can be approximated using the following Bernoulli equation:

[0316]

[0317] where ρ is the density of the fluid, υ is the fluid velocity, P is the pressure, h is the height above a reference plane (in this case the floor 220), and g is the acceleration due to gravity.

[0318] For the pressure under the porous material 168, the above Bernoulli equation can be rewritten as:

[0319]

[0320] For a velocity of 1.5 m / s, ΔP = 1125 Pa; for a velocity of 3.16 m / s, ΔP = 5000 Pa.

[0321] This indicates that at higher speeds, more liquid will remain on the floor 220, because at higher speeds the floor 220 will pull the liquid more strongly, and this has been observed with the cleaning head 100 according to the present disclosure.

[0322] Movement of the cleaning head 100, for example at a speed of about 1.5 m / s, can create a shear flow in the liquid layer 222, creating a shear force 232 acting on the liquid in the porous material 168 that pulls the liquid towards the surface 218 to be cleaned. The water is also pushed in the direction of the dirt inlet 142A by the underpressure 226. The underpressure can be selected such that the force that moves the liquid 222 towards the (one or more) dirt inlets 142A exceeds the shear force 232.

[0323] The liquid pickup performance of an exemplary cleaning head 100 was evaluated, the cleaning head 100 including a porous material 168 and cleaning liquid applicator materials 126, 128 for applying a liquid (such as water) to the surface 218 to be cleaned, the cleaning liquid applicator materials 126, 128 moving over the surface 218 to be cleaned at a speed of 1.5 m / s and having different dirt inlet underpressures. The results are listed in Table 1.

[0324]

[0325] Table 1

[0326] Another advantage of the liquid pickup principle described herein can be lower power consumption, particularly in examples where the underpressure generator 178 is powered.

[0327] Conventional vacuum cleaners capable of picking up water need to generate a significant airspeed and / or brush force in order to create sufficient shear force on the water droplets to cause the water droplets to enter the vacuum cleaner. Typical power consumption values for such vacuum cleaners are in the hundreds of watts.

[0328] The following calculations show the relatively low mechanical power required for liquid (such as water) pickup according to the present disclosure.

[0329] P = Φ * ΔP

[0330] where P is the mechanical power in watts; Ф is the fluid flow rate in m 3 / s; and ΔP is the underpressure in the (one or more) dirt inlets 142A in Pa.

[0331] For example, with an underpressure of 5000 Pa and a fluid flow rate of 100 cm 3 / minute, the power is 8.3 * 10 -3 watts.

[0332] If the underpressure generator 178 is powered by a conventional battery that provides a runtime of, for example, 28 minutes in a wet cleaning device with a mechanical power consumption of approximately 50 watts, the runtime in the current case would be 168,000 minutes, in other words, more than 100 days.

[0333] Thus, an electric wet cleaning device having a cleaning head 100 according to the present disclosure may only rarely need to recharge its battery (in an example including such a battery to power the wet cleaning device), and / or may be lighter due to, for example, the minimum battery capacity required for a 1-hour runtime. Regarding the latter, it should be noted that the battery for a conventional handheld wet cleaning device can weigh approximately 0.5 kg and can thus significantly increase the total weight of the wet cleaning device.

[0334] Table 2 provides a comparison of mechanical power between a conventional vacuum cleaner and the above various states regarding the wet cleaning device according to the present disclosure.

[0335]

[0336] Table 2

[0337] More generally, the present invention provides a wet cleaning device including a cleaning head 100. The cleaning head 100 has at least one dirt inlet 142A, 142B and a porous material 168 covering at least one dirt inlet 142A, 142B. The wet cleaning device further includes an underpressure generator 178 configured to provide a pressure difference between the interior of the wet cleaning device and atmospheric pressure for sucking a fluid through the porous material 168 and into at least one dirt inlet 142A, 142B.

[0338] The underpressure generator 178 is included in an underpressure generator device configured to control the flow inside the wet cleaning device based on the pressure on the inner side between the porous material 168 and the underpressure generator 178 to suck the fluid through the porous material 168 into at least one dirt inlet 142A, 142B.

[0339] In some embodiments, the pressure difference is in the range of 2000 Pa to 13,500 Pa.

[0340] The two endpoints of the 2000 Pa to 13,500 Pa range for the pressure difference are purposefully selected.

[0341] The 2000 Pa lower limit reflects that the cleaning head 100 will typically move on a surface to be cleaned, such as a floor, and when the speed of the cleaning head 100 on the floor increases, the accompanying static pressure drop means that the liquid is pulled towards the floor. As described above, this behavior can be approximated by the Bernoulli equation.

[0342] Referring to Table 1 above, it has been found that when the cleaning head 100 moves over the surface to be cleaned at a typical speed, below 2000 Pa, excessive liquid may remain on the surface to be cleaned.

[0343] Based on the minimum typical speed at which the user moves the cleaning head 100 over the surface to be cleaned, a minimum underpressure of 2000 Pa is set accordingly, so as to ensure that the underpressure is sufficient to suck the liquid into the interior of the wet cleaning device, without the user having to significantly slow down or stop the movement of the cleaning head 100 over the surface to be cleaned in order to pick up the liquid.

[0344] The purpose of defining the upper limit of 13500 Pa is to ensure that the liquid delivery through the porous material 168 is fast enough.

[0345] There is a trade-off between the magnitude of the underpressure that can be maintained and the flow resistance through the porous material 168, which determines the rate at which the liquid can pass through the porous material 168. This trade-off is reflected in the choice of the 13500 Pa upper limit of this range.

[0346] In some embodiments, the pressure difference is from 2000 Pa to 12500 Pa, preferably from 5000 Pa to 9000 Pa, and most preferably from 7000 Pa to 9000 Pa. These ranges can reflect a particularly enhanced liquid pick-up observed during the movement of the cleaning head 100, combined with a relatively low flow resistance through the porous material 168.

[0347] This pressure difference can be directly and positively verified in a given wet cleaning device, for example, by drilling a hole in the pipe of the wet cleaning device that is fluidly connected to the (multiple) dirt inlets 142A, 142B and using this hole to connect to a pneumatic pressure sensor itself, which has a pipe with a membrane covering its end; thus, an airtight connection is used to connect the sensor. The sensor can be arranged to avoid disturbing the flow, so those skilled in the art will arrange the sensor to avoid, for example, creating a bypass flow. There is no flow into or out of the sensor: only pressure is transmitted. In this way, the flow of the appliance is never impaired (therefore, it can still be maintained at the set level despite the installation of the sensor).

[0348] The pressure sensor is connected between the porous material 168 and the underpressure generator 178 and as close as possible to the porous material 168 to minimize the influence of other factors (such as flow resistance, etc.) on the sensed pressure difference.

[0349] The sensing element / membrane of the pressure sensor / pressure gauge is ideally arranged / located in the pressure sensor such that the sensing element can be placed directly (without a connecting pipe) in the pipe or in the cavity 150 behind the porous material 168.

[0350] As will be understood by those skilled in the art, the measurement error can be minimized by positioning the diaphragm of the pressure sensor (in other words, the diaphragm manometer) such that the diaphragm is positioned at the wall of the tube (or exposed to the cavity 150) (in other words, in line with the wall of the tube).

[0351] It should be noted that air bubbles in the narrow tube can create resistance (capillary / surface tension effect) and can thus affect the measurement. Thus, those skilled in the art will further understand that care should also be taken that the air bubbles (water-air surface) do not unduly affect the differential pressure measurement.

[0352] It should also be noted that the water column present between the pressure sensor and the porous material 168 should be subtracted from the measurement result (if such a water column exists during the measurement) to compensate for the static pressure generated by the water column.

[0353] Once the pressure sensor is arranged as described above, it can be determined that the maintenance of the underpressure is due to the porous material 168 and not some other component, such as a valve. Any such component that affects the underpressure presented to the porous material 168 should be made inoperable for the purpose of performing the measurement.

[0354] When performing the differential pressure measurement, the component(s) for dispensing the cleaning liquid (if the wet cleaning device is configured to deliver the cleaning liquid) are disengaged.

[0355] The wet cleaning device is turned on (at the desired settings) such that the pick-up system including the underpressure generator 178 is activated. Data from the pressure sensor is started to be recorded.

[0356] The pick-up area of the cleaning head 100 is suspended in a water layer with a maximum depth of 5 mm.

[0357] The pick-up area is then lifted out of the water without tilting it in any way (such that the cleaning head 100 remains in the cleaning position as if it were positioned to clean the floor), such that the water no longer contacts the porous material 168. At this time, the "free water" will be removed from the porous material 168, all the pores will enter their "blocked state", and the burst pressure is determinable. The measurement result will be similar to Figure 12 the curve shown in, again noting that an equilibrium is established in the end state 198, where the applied flow results in an underpressure that does not cause more fluid blocks to burst.

[0358] The burst pressure obtained from this measurement result, with reference to the end state 198, is the "differential pressure between the inside of the wet cleaning device and the atmospheric pressure for sucking fluid through the porous material 168 and into at least one of the dirty inlets 142A, 142B". It is verified whether the range of 2000 Pa to 13500 Pa is satisfied according to the measurement result.

[0359] It should be noted that the porous material 168 can be arranged to contact the liquid on the surface to be cleaned, as described above. Thus, the porous material 168 can be defined as from the outer surface of the porous material 168 that can be exposed to the liquid on the surface to be cleaned to the inner surface of the porous material 168 that is exposed to at least one dirt inlet.

[0360] ASTM F316-03, 2019, Test A provides the measurement of the bubble point pressure. Although this standard method was developed for non-fiber membrane filters, this procedure can be replicated for the porous material 168 according to the present disclosure.

[0361] In short, a bubble point test for determining the limiting pore diameter, in other words the maximum pore diameter, is performed by pre-wetting a sample of the porous material 168, increasing the gas pressure upstream of the porous material 168 at a predetermined rate, and observing the bubbles downstream to indicate the passage of gas through the largest diameter pores of the porous material 168.

[0362] Like the membrane filter described in ASTM F316-03, 2019, Test A, the porous material 168 can (at least approximately) have discrete pores extending from one side of the porous material 168 to the other, similar to capillaries. The bubble point test is based on the principle that the wetting liquid is held in these capillary pores by capillary attraction and surface tension, and the minimum pressure required to force the liquid out of these pores is a function of the pore diameter. The pressure at which a stable bubble flow appears in this test is called the "bubble point pressure".

[0363] It should be noted that ASTM F316-03, 2019, Test A is based on the assumption that the pores are approximately capillary pores with a circular cross-section, so the limiting pore diameter should be considered only an empirical estimate of the maximum pore diameter based on this premise.

[0364] Like the test procedure, replicate the test device specified in ASTM F316-03, 2019, Test A.

[0365] 1. A sample of the porous material (2 inches (50.8 mm) in diameter; held in a circular holder (e.g., having an opening / effective area with a diameter of 47 mm) is completely wetted by floating it on a liquid bath (note that if necessary, a vacuum chamber can be used to assist in wetting the sample). For a water-wettable sample, place the sample in water and fully immerse it.

[0366] 2. Place the wetted sample of the porous material in the filter holder of the test device.

[0367] 3. Place a fine mesh (100×100 mesh) on the sample of the porous material; the fine mesh is the first part of the two-layer structure specified by the standard.

[0368] 4. The second part of the two-layer structure in the form of a perforated metal component for increased rigidity is placed on the fine mesh.

[0369] 5. The support ring is placed on the stack and fixed in place with bolts. At this time, a slight gas pressure can be applied to eliminate possible liquid backflow.

[0370] 6. The perforated metal component is covered with a test liquid of 2 mm - 3 mm (type IV water as required by the standard when the sample is wetted with water).

[0371] 7. Then the gas pressure is increased, and the lowest pressure at which a steady bubble flow rises from the central region of the reservoir is recorded (see Figure 5 of ASTM F316 - 03, 2019, Test A; note that bubbles observed at the edge of the reservoir are ignored for bubble point determination).

[0372] It is found that it is appropriate to first increase the pressure relatively rapidly (e.g., at about 200 Pa / second) to roughly determine the bubble point. Then the pressure is released from the sample to allow the water to flow back into the sample. Then the pressure is increased to about 80% of the expected pressure value, held at the 80% level for about 15 seconds (to ensure that all "free" water is pressed out of the sample), and then the pressure is increased again at a lower rate ≤ Pa / second until a steady bubble flow is observed.

[0373] Then the limiting pore diameter d is determined from the recorded bubble point pressure p using Equation 1 of ASTM F316 - 03, 2019, Test A: D = Cγ / p, where γ is the surface tension in mM / m (72.75 for distilled water at 20 °C), and C is 2860 when p is in Pa.

[0374] It is found that the bubble point pressure from ASTM F316 - 03, 2019, Test A is comparable to the above-mentioned rupture pressure for samples of the porous material 168, except for the case of the 0.25 μm beer filter, which can be directly explained by the forced flow present in the rupture pressure test rather than in the bubble point test. The results of various samples of the porous material 168 are provided in Table A.

[0375]

[0376]

[0377] Table A

[0378] In some embodiments, the limiting pore diameter of the porous material 168 measured using ASTM F316 - 03, 2019, Test A is equal to or greater than 15 μm.

[0379] Such a limiting pore diameter equal to or greater than 15 μm can help maintain a relatively large underpressure while ensuring that the pores are large enough to effectively deliver liquid. Regarding the latter, it should be noted that this observation is supported by theory, noting that when approximating using the Poiseuille equation provided above, for smaller pores, the flow resistance can increase to the fourth power.

[0380] In some embodiments, the limiting pore diameter of the porous material 168 measured using ASTM F316 - 03, 2019, Test A is equal to or less than 105 μm. The upper limit of the limiting pore diameter helps ensure that the porous material 168 can maintain sufficient underpressure.

[0381] As described above, ASTM F316 - 03, 2019, Test A uses cylindrical pores. For illustrative purposes only (and thus should not be regarded as the limiting value of the limiting pore diameter from ASTM F316 - 03, 2019, Test A provided herein), it should be noted that the limiting pore diameter can be adjusted with a Tortoise factor (TF) to compensate for the non - circularity of the pores, where the Tortoise factor (TF) is an empirical factor derived from solid - line filters. The 1.3 - 1.65 expansion of the TF recommended in ASTM E3278 - 21 (see Section 4.2.1 of this standard) may result in an approximately 27% expansion of the pore size. For illustrative purposes only, Table B shows the above - mentioned limiting pore diameter endpoints when adjusted using TF. Note that the limiting pore diameter of ASTM F316 - 03, 2019, Test A provides a measure of the maximum pore size through which particles can pass, so the TF can compensate for the fact that "triangular" pores can only allow spherical particles much smaller than the triangular surface to pass.

[0382]

[0383] Table B

[0384] In some embodiments, the underpressure generator is configured to provide a flow rate through the porous material 168 that is less than or equal to 2000 cm 3 / minute.

[0385] Such a flow rate can be significantly lower than the flow rate of the above - mentioned conventional wet vacuum cleaners. Since power is equal to the flow rate multiplied by the pressure difference, by combining this maximum 2000 cm 3 / minute flow rate with the above - mentioned maximum 13500 Pa pressure difference as the maximum power consumption scenario, the power consumption of the wet cleaning device can be minimized. Referring to Table 2 above, this can enable the wet cleaning device to be manufactured relatively compactly, for example, using a smaller battery, and / or having a relatively long runtime.

[0386] Alternatively or additionally, the underpressure generator can be configured to provide a flow rate equal to or greater than 15 cm 3The flow rate through the porous material 168 is / minute. This can help pick up liquid from the surface to be cleaned quickly enough. In some embodiments, 15 cm 3 The lower limit of / minute can be set to be equal to or exceed the flow rate of the cleaning liquid from the (one or more) cleaning liquid outlets 104 also included in the cleaning head 100.

[0387] In some embodiments, the underpressure generator is configured to provide a flow rate through the porous material equal to or greater than 40 cm 3 / minute. In addition to helping with effective liquid pickup, in some embodiments, this 40 cm 3 / minute can be set to be equal to or exceed the flow rate of the cleaning liquid from the cleaning liquid outlet also included in the cleaning head, and the minimum cleaning liquid flow rate is set to ensure sufficient supply of the cleaning liquid to the surface to be cleaned.

[0388] The underpressure generator can be configured to provide a flow rate through the porous material of 80 cm 3 / minute - 750 cm 3 / minute, more preferably 100 cm 3 / minute - 300 cm 3 / minute, and most preferably 150 cm 3 / minute - 300 cm 3 / minute. Such a flow rate can utilize the underpressure holding ability of the porous material 168 and can ensure sufficient liquid pickup while limiting energy consumption.

[0389] In some embodiments, the porous material 168 has a thickness less than or equal to 10 mm, more preferably less than or equal to 5 mm, and most preferably less than or equal to 3 mm. Such a maximum thickness can help minimize the flow resistance through the porous material 168.

[0390] The thickness of the porous material 168 can be determined by using a 0.01 mm precision gauge and two grounded metal plates for accommodating the porous material 168 therebetween (the upper plate for applying positive pressure is 70 mm × 30 mm, and the lower plate for supporting the porous material sample thereon has an area larger than the 70 mm × 30 mm surface of the upper plate for easy alignment). This arrangement is configured to apply a pressure of 864.2 N / m 2 to the porous material sample (70 mm × 30 mm). The relevant measurement parameters are shown in Table C:

[0391]

[0392] Table C

[0393] The thicknesses of several samples are determined using this method, and the data are provided in Table D:

[0394]

[0395]

[0396] Table D

[0397] In some embodiments, the fluid delivery pressure flowing through the porous material 168 at 200 cm 3 / minute is less than 0.25 times the bubble point pressure as determined by ASTM F316 - 03, 2019, Test A.

[0398] This may mean that the flow resistance through the porous material 168 remains at a relatively low level.

[0399] Another set of burst pressure tests (similar to the above tests) was conducted using the porous materials corresponding to sample number 18 in Table A and sample numbers 22 - 25 in Table D and a Supplier F fabric with a thickness of 0.8 mm. The flow pressure drop and burst pressure of each sample were recorded, and the results (average of at least two measurements) are listed in Table E. In these experiments, a flow rate of 89 cm 3 / minute was used, and the diameter of the circular mesh under the sample (extending through the "active area" of the sample) was 80 mm.

[0400] Porous material sample number / description Flow pressure drop / Pa Burst pressure / Pa 15 19000 13920 Supplier F fabric; thickness 0.8 mm 120 5539 22 2910 11495 23 8921 12405 24 12359 13000 25 15830 13363 26 16617 14100 27 18127 14173

[0401] Table E

[0402] It can be seen that the burst pressure increases as more layers are stacked on top of each other, as previously described. However, when more layers are added, the delivery flow pressure can increase faster than the burst pressure, and in the case of sample numbers 22 to 27, when the porous material has four stacked double layers (at sample number 25), the delivery flow pressure exceeds the burst pressure.

[0403] Compared to what is clearly seen from samples 22 to 27, the delivery flow pressure rises faster with more layers; however, the air in the system may mean that the data starts to show compressibility, especially for sample numbers 25 to 27.

[0404] More generally, these data can indicate that the wet cleaning device can operate when the delivery flow pressure (at the desired flow rate) is below the burst pressure.

[0405] For the tests whose results are listed in Table E, the flow rate was 89 cm 3 / minute, and the effective area of the fabric was 5030 mm 2 . In the case of the cleaning head 100, the effective area can be approximately 1750 mm 2Therefore, when a conveying flow pressure is applied to the porous material 168 of the cleaning head 100, the actual flow rate through the porous material 168 can be 0.35 times lower (1750 / 5030) than the flow rate used in these tests.

[0406] This may mean that at the point where the conveying flow pressure is equal to the burst pressure (e.g., at sample number 24), the maximum flow rate that the porous material 168 can withstand is approximately (0.35 * 98) 31 cm 3 / minute. Even if more layers are added to the porous material 168, the burst pressure can remain roughly the same while the conveying flow pressure increases, thus reducing this value even more.

[0407] Note that in the above burst pressure tests, the entire surface of the test sample was covered with water, so the entire area of the porous material 168 delivered water. However, in practice, the area of the cleaning head 100 that contacts the floor (e.g., 5 mm wide and 350 mm long) delivers water, while the area of the porous material 168 adjacent to this area can also deliver air. This may mean that when, for example, using four double layers (in the case of sample number 25), and the burst pressure of the porous material is lower than the water delivery pressure, the perimeter of the porous material 168 may start to rupture, thus releasing air and resulting in settlement at the burst pressure. The active / pickup area can maintain a relatively low pressure, so the liquid can be picked up relatively slowly, and thus the liquid can remain on the surface to be cleaned. On the contrary, in the case where the porous material 168 has a relatively low conveying flow pressure and a significantly larger burst pressure (e.g., in the case of the 0.8 mm thick fabric from supplier F, where the burst pressure is 50 times higher than the conveying flow pressure), the pickup flow may be very high.

[0408] In summary, the wet cleaning device can operate when the burst pressure is higher than the conveying flow pressure, but in order to enable picking up at a higher speed, the burst pressure can be at least twice the conveying flow pressure.

[0409] In some non - restrictive examples, the cleaning head 100 can deliver the cleaning liquid at a flow rate of 40 cm 3 / minute. In the case where the flow rate through the porous material 168 is 85% of the flow rate of this cleaning liquid on the smooth surface to be cleaned, i.e., a pickup rate of 34 cm 3 / minute, the pickup rate can be compared with the 31 cm 3 / minute estimated above for sample number 24.

[0410] In some non - restrictive examples, some tolerances can be introduced, for example, to account for a cleaning liquid flow rate of 20 cm 3 / minute, thus resulting in an upper limit of the thickness of the porous material 168 of approximately 5 mm (see sample number 25).

[0411] As described above, the porous material 168 may include one or more of porous fabrics, porous plastics, and foams.

[0412] Such a porous plastic may take the form of, for example, a sintered mesh of plastic particles.

[0413] In embodiments where the porous material 168 includes such a porous plastic, one or more additional layers of porous material, such as including a porous fabric, such as a woven porous fabric, may be disposed on the outer surface of the porous plastic. Such additional layer(s) of porous material may be more wettable by water than the porous plastic and thus may be more suitable for contacting the surface to be cleaned when wetted by water.

[0414] Particularly mentioned porous materials include porous woven fabrics, most preferably woven microfiber fabrics. Such woven microfiber fabrics may facilitate obtaining the desired underpressure in a wet cleaning device.

[0415] Such a porous woven fabric, particularly such a woven microfiber fabric, may be configured, in particular by the tightness of its weave, to meet the above range of limiting pore diameters.

[0416] The specifications of particularly suitable woven fabrics are provided in Table F as illustrative non-limiting examples.

[0417]

[0418]

[0419] Table F

[0420] Figures 17 to 23 An example of how the porous material 168 is mounted in the cleaning head 100 is schematically depicted.

[0421] The porous material 168 may be mounted in any suitable manner. In some embodiments, as Figure 17 shown, the cleaning head 100 includes a support member 236, such as a rigid support member 236, for supporting the porous material 168. The support member 236 may be formed of any suitable material, such as an engineering thermoplastic.

[0422] In some embodiments, the cleaning head 100 includes an elastomeric material 238 on which the porous material 168 is disposed. If, for example, there are relatively hard protrusions on the surface 218 to be cleaned in contact with the porous material 168, the elastic deformation of such an elastomeric material 238 may reduce the risk of damaging the porous material 168. Alternatively or additionally, the elastomeric material 238 may help the porous material 168 to follow any contour of the surface 218 to be cleaned.

[0423] The elastomeric material 238 can for example be or include silicone rubber. Other elastomeric materials such as polydienes, for example polybutadiene, thermoplastic elastomers, etc. can also be considered to be included in or define the elastomeric material 238.

[0424] Alternatively or additionally, the elastomeric material can be less than 50 Shore A, preferably less than 20 Shore A, and most preferably less than 10 Shore A.

[0425] In a non-limiting example, the elastomeric material is 4 Shore A silicone rubber.

[0426] In embodiments where the cleaning head 100 includes a support member 236, for example a rigid support member 236, the elastomeric material 238 can be disposed between the support member 236 and the porous material 168. Figure 17 Such an example is shown in.

[0427] In embodiments where the cleaning head 100 includes the above-mentioned protruding elements, the protruding elements can include the elastomeric material 238, which will be described in more detail below.

[0428] Returning to Figure 17 In the non-limiting example shown, the impermeable portion 146 is in the form of a polymer (e.g., thermoplastic) film, where the seal 152 is disposed between the polymer film and the porous material layer 114 included in the porous material 168. Additionally, the liquid delivery support structure 154 included in this particular example is in the form of a mesh or a stack of mesh layers.

[0429] In some embodiments, for example Figure 18 In the non-limiting embodiment shown, the impermeable portion 146 is defined by (a plurality of) impermeable seal portions, such as multiple polymer films, extending from the elastomeric material 238 to the porous material layer 114 of the porous material 168. In this case, it may not be necessary for the polymer film to extend laterally on the inner surface of the porous material layer 114.

[0430] In some embodiments, the elastomeric material 238 includes the impermeable portion 146 sealed to the porous material layer 114 of the porous material 168. Thus, in this embodiment, the above-mentioned polymer film and multiple polymer films are eliminated and can be omitted. In this way, the number of components in the cleaning head 100 can be reduced, thereby facilitating manufacturing.

[0431] In some embodiments, as Figure 19As shown, the liquid delivery support structure 154 is provided at least in part or entirely by a surface pattern on and / or in the surface of the porous material layer 114 of the elastomeric material 238 facing the porous material 168. Replacing the (multiple) mesh with a surface pattern on the surface of the elastomeric material 238 can help reduce the number of components in the cleaning head 100. In other aspects, Figure 19 The example shown corresponds to Figure 18 the example shown.

[0432] In some embodiments, as Figure 20 shown, the support member 236 includes an impermeable portion 146 sealed to the porous material layer 114 of the porous material 168. In other words, the seal between the support member 236 and the porous material 168 is provided by the protruding portion of the support member 236 that seals against the porous material 168. Thus, the polymer film is not necessary in this example as a direct connection between the porous material layer 114 and the support member 236 can be used to create the seal. In other aspects, Figure 20 The example shown corresponds to Figure 17 the example shown.

[0433] Figure 21 The non-limiting example shown in corresponds to Figure 20 the non-limiting example shown in, except that the liquid delivery support structure 154 is provided at least in part or entirely by a surface pattern on and / or in the surface of the porous material layer 114 of the elastomeric material 238 facing the porous material 168.

[0434] Figure 22 The non-limiting example shown in corresponds to Figure 18 the non-limiting example shown in, except that the elastomeric material 238 is disposed within the cavity 150 provided between the polymer film as the impermeable portion 146 and the porous material layer 114 of the porous material 168.

[0435] Figure 23 The non-limiting example shown in corresponds to Figure 22 the non-limiting example shown in, except that the liquid delivery support structure 154 is provided at least in part or entirely by a surface pattern on and / or in the surface of the porous material layer 114 of the elastomeric material 238 facing the porous material 168.

[0436] At this point, it is to be reiterated that the above-described liquid pickup region PR of the porous material layer 114 (defined by the sealed attachment of the porous material layer 114 around each of at least one of the dirt inlets 142A, 142B, for example) can be arranged relative to each of the at least one cleaning liquid outlet 104 to allow the cleaning liquid to bypass the liquid pickup region PR and reach or at least be directed towards the surface 218 to be cleaned. This arrangement of the liquid pickup region PR relative to each cleaning liquid outlet of the (one or more) cleaning liquid outlets 104 can be achieved in any suitable manner.

[0437] In some embodiments, for example Figure 24 as shown, each cleaning liquid outlet 104 of the cleaning liquid outlets is arranged in one or more dispensing members that are spatially separated from the porous material layer 114. By arranging the (one or more) cleaning liquid outlets 104 in such separate one or more dispensing members, the cleaning liquid can be delivered towards the surface 218 to be cleaned along Figure 24 the direction of the arrow 240 without initially contacting the porous material layer 114.

[0438] In Figure 24 the non-limiting example shown, the dispensing members correspond to the above-described cleaning liquid dispensing belts 108, 124.

[0439] In Figure 24 it, the spatial separation is evident through a gap 242, such as an air gap 242, provided between the porous material layer 114 and the cleaning liquid dispensing belts 108, 124.

[0440] In some embodiments, as Figure 25 shown, the porous material 168 includes one or more of the above-described additional porous material layers 156, and the cleaning head 100 includes a separable element 244 that includes one or more of the additional porous material layers 156. Separation of the separable element 244 separates the one or more additional porous material layers 156 from the porous material layer 114.

[0441] In some embodiments, the separable element 244 includes the above-described cleaning liquid applicator materials 126, 128. In this way, one or more of the additional porous material layers 156 can be directly replaced while replacing the cleaning liquid applicator materials 126, 128. For example, the cleaning liquid applicator materials 126, 128 can be attached (e.g., adhered) to one or more of the additional porous material layers 156 in the separable element 244.

[0442] In some embodiments, such as in Figure 25In the non-limiting example shown, the cleaning liquid applicator materials 126, 128 include the first and second applicator portions 126, 128 described above, wherein the first attachment 246A connects one or more additional porous material layers 156 to the first applicator portion 126, and the second attachment 246B connects one or more additional porous material layers 156 to the second applicator portion 128. The following refers to Figure 33E describe another example.

[0443] In some embodiments, the cleaning head 100 includes a support for supporting the porous material layer 114, and the cleaning head 100 includes a separable (and / or attachable) member 248, the separable member 248 including the porous material layer 114, and separation of the separable member 248 separates the porous material layer 114 from the support.

[0444] In addition to the porous material layer 114, such a separable member 248 may include the impermeable portion 146 described above, for example including or in the form of a polymer film, wherein at least one dirt inlet 142A is defined by one or more orifices in the impermeable portion 146.

[0445] In some non-limiting examples, such as Figure 26 shown, the separable (and / or attachable) member 248 also includes the liquid delivery support structure 154 described above.

[0446] For example, the liquid delivery support structure 154 may be disposed in a cavity 150 between the porous material layer 114 and the impermeable portion 146.

[0447] When the cleaning head 100 includes both the separable element 244 and the separable element 248, the separable element 244 may be separable, for example, independently of the separable element 248, and the separable element 248 may be separable independently of the separable element 244.

[0448] In some embodiments, as Figure 27 shown, the separable member 248 also includes the cleaning liquid applicator materials 126, 128. For example, when the separable member 248 includes the impermeable portion 146, the cleaning liquid applicator materials 126, 128 may be attached to (e.g., adhered to) the impermeable portion 146.

[0449] In Figure 27 the non-limiting example shown, the cleaning liquid applicator materials 126, 128 include the first and second applicator portions 126, 128 described above, a first connection 250A connects a first side of the impermeable portion 146 to the first applicator portion 126, and a second connection 250B connects a second side of the impermeable portion 146 to the second applicator portion 128.

[0450] Figure 28 Schematically shows an exemplary cleaning head 100, which includes a separable member 248 that does not include cleaning liquid applicator materials 126, 128. However, the cleaning liquid applicator materials 126, 128 are still separable, and in this example, each of the first and second applicator portions 126, 128 can be separated from the cleaning liquid outlet 104 independently of each other and independently of the separable member 248.

[0451] More generally, the present disclosure provides the attachable (and / or separable) member 248 itself. The attachable member 248 can be adapted to be attached to a wet cleaning device having a vacuum generator 178. In at least some embodiments, the attachable member 248 includes a porous material layer 114; and at least one dirt inlet 142A, 142B, and when the attachable member 248 is attached to the wet cleaning device, the vacuum generator 178 can be fluidly connected to the at least one dirt inlet 142A, 142B, wherein the liquid pickup region PR of the porous material layer 114 is defined by a sealed attachment of the porous material layer 114 around the at least one dirt inlet 142A, 142B.

[0452] Such an attachable member 248 enables the replacement of the porous material layer 114 without the need to reseal the porous material layer 114 to the (one or more) dirt inlets 142A, 142B.

[0453] In some embodiments, the attachable member 248 includes an impermeable portion 146, and the at least one dirt inlet 142A, 142B is defined by one or more orifices provided in the impermeable portion 146 and / or between the impermeable portion 146 and the porous material layer 114. Such an attachable member 248 can enable the replacement of the porous material layer 114 without the need to reseal the impermeable portion 146 to the porous material layer 114.

[0454] In some embodiments, the at least one dirt inlet 142A, 142B is exposed to a cavity 150 between the porous material layer 114 and the impermeable portion 146, a liquid delivery support structure 154 is disposed in the cavity 150, and provides one or more flow paths in the liquid pickup region PR between the porous material layer 114 and the at least one dirt inlet 142A, 142B.

[0455] A wet cleaning device, such as a cleaning head 100 included in a wet cleaning device, may include at least one cleaning liquid outlet 104 through which, as previously described, cleaning liquid may be delivered. When at least one dirt inlet of the attachable member 248 is fluidly connected to the underpressure generator 178, a liquid pickup area PR may be arranged relative to each of the at least one cleaning liquid outlet 104 such that the liquid pickup area PR is bypassed by the cleaning liquid delivered towards the surface 218 to be cleaned.

[0456] Figure 29 An exemplary cleaning head 100 including a separable element 244 is schematically shown. The separable element 244 includes, in this example, one or more additional porous material layers 156. Further, in this non-limiting example, in this example, each of the first and second applicator portions 126, 128 may be separated from the cleaning liquid outlet 104 independently of each other and independently of the separable element 244.

[0457] Figure 30 An exemplary cleaning head 100 is shown in which a porous material (in this case a porous material layer 114) contacts cleaning liquid applicator fabrics 126, 128. As previously explained, this configuration may help prevent an excessive accumulation of cleaning liquid in the cleaning liquid applicator materials 126, 128 and may thus help minimize overwetting of the surface 218 to be cleaned, for example by dripping the cleaning liquid from the cleaning liquid applicator materials 126, 128 onto the surface 218 to be cleaned.

[0458] In this particular example, enhanced control of the humidity of the cleaning liquid applicator materials 126, 128 may be achieved since an edge portion 134 of the porous material layer 114 abuts against opposite edge portions 136 of the cleaning liquid applicator materials 126, 128.

[0459] More specifically, in this non-limiting example, the cleaning liquid applicator materials 126, 128 include a first applicator portion 126 and a second applicator portion 128 such that the opposite edge portions 136 of the cleaning liquid applicator material are included in the first applicator portion 126, as shown. Further, in this example, another edge portion 138 of the porous material layer 114 abuts against additional opposite edge portions 140 of the second applicator portion 128.

[0460] However, in Figure 30In the example shown, the liquid pickup region PR of the porous material layer 114 (defined by the sealed attachment of the porous material layer 114 around each of at least one soiling inlet 142A, 142B, for example) is arranged relative to each of the cleaning liquid outlets 104, so as to allow the cleaning liquid to bypass the liquid pickup region PR. In this regard, in this example, the cleaning liquid outlets 104 are arranged in a dispensing member, which in this example is in the form of cleaning liquid dispensing belts 108, 124, which are spatially separated from the porous material layer 114. The latter is reflected by the gap 242 (such as an air gap 242) between the porous material layer 114 and the dispensing members 108, 124.

[0461] It is reiterated that the porous material 168 including the porous material layer 114 is different from the cleaning liquid applicator materials 126, 128 in that the porous material 168 is denser than the cleaning liquid applicator materials 126, 128, for example due to a tighter weave of the microfiber fabric.

[0462] In some embodiments, as Figure 31 shown, the cleaning head 100 includes a portion 120 facing the surface 218 to be cleaned, and the protruding element 252 is mounted near the portion 120. Thus, the protruding element 252 is an element mounted separately relative to the portion 120. The protruding element 252 protrudes from the cleaning head 100 in the direction of the surface 218 to be cleaned. In this way, the cleaning head 100 can swing in a first direction on the protruding element 252 to bring the portion 120 into contact with the surface 218 to be cleaned, and swing in a second direction opposite to the first direction on the protruding element 252 to separate the portion 120 from the surface 218 to be cleaned, as described above.

[0463] In some embodiments, as Figure 31 shown, the cleaning head 100 includes a support member 236, such as a rigid support member 236, and the protruding element 252 is mounted to the support member 236 by an attachment.

[0464] It should be noted that the cleaning head 100 can be attached or attachable to a suitable handle (not visible) to assist in moving the cleaning head 100. For this purpose, the cleaning head 100 can include a coupling point 254, to which such a handle can be coupled, for example pivotally coupled.

[0465] Referring to Figure 31 , the cleaning head 100 moves on the surface 218 to be cleaned by applying a force F 运动 The movement of the cleaning head 100 on the surface 218 to be cleaned may not be without resistance. The weight F of the cleaning head 100 重力 and / or the user pressing the cleaning head 100 towards the surface 218 to be cleaned can generate a force Fn perpendicular to the surface 218 to be cleaned.

[0466] The cleaning head 100 can be wet and thus can operate in a viscous friction state and a dry state; the former generates a viscous frictional force Fv, while the latter generates a Coulomb frictional force Fc, which is controlled by a normal force Fn and a coefficient of friction f. The resulting drag force Fr is approximated by the following equation.

[0467]

[0468] where the forces Fr, Fv, Fc, and Fn are in Newtons; μ is the dynamic viscosity in Pa·s; A is the contact area in m 2 ²; u is the velocity in m / s; and y is the thickness of the liquid layer in m.

[0469] The above equation shows that both a larger contact area A and a liquid layer with a thickness y approaching zero tend to increase the viscous friction term and thus increase the resulting drag force Fr.

[0470] It should also be noted that a relatively large contact area A required for effectively picking up liquid on the uneven surface 218 to be cleaned can result in a relatively high drag force Fr, especially on a relatively flat / smooth surface 218 to be cleaned.

[0471] Thus, in at least some embodiments, the protruding element 252 includes a porous material 168. Since the contact area A between the porous material 168 and the surface 218 to be cleaned is limited, the movement resistance of the cleaning head 100 on the surface to be cleaned can be reduced.

[0472] The porous material layer 114 of the porous material 168 can be included in the protruding element 252.

[0473] In some embodiments, the liquid pickup region PR of the porous material layer 114 is included in the protruding element 252 and terminates between the protruding element 252 and the portion 120. In this way, the area of the porous material layer 114 to which suction is applied is restricted to the protruding element 252, thereby helping to reduce the movement resistance.

[0474] Alternatively or additionally, at least one dirt inlet 142A, 142B can be defined in the protruding element 252. Thus, suction can be applied to the portion of the cleaning head 100 that contacts the surface 218 to be cleaned, in other words, to the protruding element 252, and the contact of the protruding element 252 with the surface 218 to be cleaned is reduced, for example due to its swinging function.

[0475] In embodiments where the cleaning head 100 includes a portion 120 and an additional portion 122 facing the surface 218 to be cleaned, the protruding element 252 can be mounted between the portion 120 and the additional portion 122. In this way, the cleaning head 100 can swing forward on the protruding element 252 to bring the portion 120 into contact with the surface 218 to be cleaned, asFigure 31 as shown, and swing backward to bring additional portion 122 into contact with the surface 218 to be cleaned.

[0476] In such an embodiment, the liquid pickup region PR of the porous material layer 114 may extend between the portion 120 and the additional portion 122 and terminate between the projecting element 252 and the portion 120 and between the projecting element 252 and the additional portion 122.

[0477] In Figure 31 In the non - limiting example shown, the adjacent opposite edge portions 134, 136 of the porous material 168 and the cleaning liquid applicator materials 126, 128 are positioned between the projecting element 252 and the portion 120. In this way, excess cleaning liquid extruded from the cleaning liquid applicator materials 126, 128 between the projecting element 252 and the cleaning liquid applicator materials 126, 128, for example, by the swinging of the cleaning head 100, can be effectively delivered via the porous material 168 into the dirt inlets 142A, 142B.

[0478] In particular, Figure 31 the portion 120 shown includes a first applicator portion 126, and the additional portion 122 includes a second applicator portion 128. Further, in this example, the adjacent opposite edge portions 134, 136 of the porous material 168 and the first applicator portion 126 are positioned between the projecting element 252 and the portion 120, and the adjacent opposite additional edge portions 138, 140 of the porous material 168 and the second applicator portion 128 are positioned between the projecting element 252 and the additional portion 122. Thus, excess cleaning liquid extruded from the cleaning liquid applicator materials 126, 128 between the projecting element and the first applicator portion 126 and between the projecting element and the second applicator portion 128, for example, by swinging the cleaning head 100 forward and backward respectively, can be effectively delivered via the porous material 168 into the dirt inlets 142A, 142B.

[0479] In some embodiments, as Figure 31 shown, the projecting element 252 has a curved surface arranged to contact the surface 218 to be cleaned.

[0480] Such a curved (e.g., circular) surface of the projecting element 252 can further help to minimize the contact area between the projecting element 252 and the surface 218 to be cleaned and thus help to minimize the resistance to the movement of the cleaning head 100 on the surface 218 to be cleaned.

[0481] The curved surface of the projecting element 252 can be curved, for example, between the portion 120 and the additional portion 122, as Figure 31 shown.

[0482] In some embodiments, the projecting element 252 includes the above-mentioned elastomeric material 238 with a porous material 168 disposed thereon. The elastomeric material 238 can be or include, for example, silicone rubber and / or have a hardness of less than 50 Shore A, preferably less than 20 Shore A, and most preferably less than 10 Shore A.

[0483] Referring Figure 31 , the elastomeric material 238 can be disposed between a support member 236 (such as a rigid support member 236) and the porous material 168.

[0484] If there are relatively hard protrusions, for example, on the surface 218 to be cleaned in contact with the porous material 168, the elastic deformation of such elastomeric material 238 can reduce the risk of damaging the porous material 168. Alternatively or additionally, the elastomeric material 238 can help the porous material 168 to follow any contour of the surface 218 to be cleaned.

[0485] Alternatively or additionally, the projecting element 252 can be elastically mounted adjacent to the portion 120. For example, the projecting element 252 can be spring-mounted to the support member 236. This can help the porous material 168 to follow any contour of the surface 218 to be cleaned, thereby facilitating liquid pickup.

[0486] In embodiments where the elastomeric material 238 is included in the projecting element 252, the curvature of the curved surface of the elastomeric material 238 (e.g., the arc between the portion 120 and another portion 122) can be followed by the porous material 168 to provide the curved surface of the projecting element 252.

[0487] Although not visible in Figure 31 , the projecting element 252 can also include the above-mentioned impermeable portion 146, which includes or is in the form of a polymer film sealed to the porous material layer 114 and surrounding the dirt inlets 142A, 142B. In such an example, the underpressure present behind the porous material 168 during the use of the cleaning head 100 can be absent in the elastomeric material 238, but is contained within the sealed cavity 150 between the porous material layer 114 and the impermeable portion 146. This can help to ensure that the elastomeric material 238 is substantially unaffected by the underpressure, especially in examples where the elastomeric material 238 itself is porous and would otherwise be prone to compaction due to the underpressure.

[0488] In other non-limiting examples, the elastomeric material 238 itself is non-porous, such that the elastomeric material 238 can be included in the impermeable portion 146 sealed to the porous material 168, for example, as described above with respect to Figure 18 described.

[0489] In Figure 31 In the non - limiting example shown, the above - mentioned liquid - delivery support structure 154 is also disposed between the porous material 168, in particular the porous material layer 114 and the impermeable portion 146. The liquid - delivery support structure 154 can be defined by or include, for example, one or more mesh layers and / or surface patterns on and / or in the surface of the elastomeric material 238, such as a curved surface.

[0490] More generally, the protruding element 252 can include, for example, the liquid - delivery support structure 154 disposed between the porous material layer 114 and at least one dirt inlet 142A, 142B.

[0491] The porous material 168 can be arranged on the elastomeric material 238 in any suitable manner, such as on the curved surface of the elastomeric material 238.

[0492] Figure 32A and Figure 32B An example of sealingly attaching the porous material layer 114 around the dirt inlets 142A, 142B to define a liquid - pick - up region PR is schematically shown. In Figure 32A and Figure 32B it is further evident the impermeable portion 146 (in this case in the form of a polymer film) and the liquid - delivery support structure 154 (in this case in the form of a mesh or multiple stacked mesh layers). The porous material 168 in this example includes or is defined by the porous material layer 114 and additional porous material layers 156, 158. Thus, the laminate includes the additional porous material layers 156, 158, the porous material layer 114, the liquid - delivery support structure 154, and the impermeable portion 146, wherein the tubes 144A, 144B providing the dirt inlets 142A, 142B are partially captured between the impermeable portion 146 and the porous material layer 114.

[0493] In Figure 32A and Figure 32B In the non - limiting example shown, the impermeable portion 146, the porous material layer 114, and the additional porous material layers 156, 158 extend in the direction of the tubes 144A, 144B beyond the liquid - delivery support layer 154. The seal 152, which is a heat - seal in this case, also extends in the direction of the tubes 144A, 144B beyond the liquid - delivery support layer 154.

[0494] By introducing clay in the region between the porous material layer 114 and the impermeable portion 146, a seal 152, i.e., an airtight seal, is provided between the porous material layer 114 and the impermeable portion 146, and the tubes 144A, 144B are guided through the impermeable portion 146. In this example, a piece of tape is then wrapped around the porous material layer 114, the impermeable portion 146, the tubes 144A, 144B, and the clay to encapsulate the clay and thus prevent it from sticking to another object.

[0495] The laminate can be flexible enough to be disposed on a curved surface of, for example, an elastomeric material 238. Additionally, for example, the laminate can be provided with one or more suitable fasteners 256A-D, which in this case are in the form of straps for securing the laminate in the cleaning head 100.

[0496] Moving on to Figure 33A and Figure 33B the non-limiting example shown in, including a laminate similar to the above regarding the porous material layer 114 and an additional first porous material layer 156 Figure 32A and Figure 32B wherein the laminate is disposed on the curved surface 258 of the elastomeric material 238 and is secured to the support member 236 via (a plurality of) fasteners 256A-D (such as ). Thus, the protruding element 252 in this example includes the elastomeric material 238 and the porous material layers 114, 156.

[0497] Since in this example the porous material layers 114, 156 follow the curvature of the curved surface 258 of the elastomeric material 238, the protruding element 252 itself includes a curved surface arranged to contact the surface 218 to be cleaned.

[0498] In Figure 33A and Figure 33B the non-limiting example shown, the protruding element 252 is mounted near the portion 120 (and in this example particularly between the portion 120 and an additional portion 122) by the elastomeric material 238 attached to the support member 236 of the cleaning head 100. In this non-limiting example, this attachment is at least partially achieved by the elastomeric material 238, which includes a protrusion 260 that is received within and engages a slot 262 defined in the support member 236. The protrusion 260 can be, for example, a push fit within the slot 262.

[0499] Figure 33AIllustrate the deformation of the cleaning liquid applicator materials 126, 128 so that at least a portion of the cleaning liquid applicator materials 126, 128 contacts the porous material. In this way, some cleaning liquid can be transferred from the cleaning liquid applicator materials 126, 128 to the porous material in a particularly controlled manner.

[0500] In Figure 33A In the non - limiting example shown, the cleaning liquid applicator materials 126, 128 include tufts of hair formed by fibers and a backing layer (not visible) that supports the tufts. As shown, such tufts can be deformed to contact the porous material, for example when contacting the surface to be cleaned and / or when wetted by a liquid such as water.

[0501] In some embodiments, the wet cleaning device includes a cleaning head 100 and a vacuum generator 178 fluidly connected to at least one dirt inlet 142A, 142B (not visible in Figure 33A and Figure 33B ). This fluid connection can be achieved through tubes 144A, 144B which, in this particular non - limiting example, extend to a single tube leading to the vacuum generator at a bifurcation point 266.

[0502] The vacuum generator 178 can be, for example, or include a pump, such as a positive displacement pump (the technical advantages of positive displacement pumps are described in more detail below). Any suitable pump can be used as long as the pump can withstand the operating pressure selected for the wet cleaning device, such as approximately 5000 Pa (see Table 1 above).

[0503] In some embodiments, the vacuum generator 178 is configured to provide suction by providing a flow rate in the range of 40 cm 3 / min to 2000 cm 3 / min, more preferably 80 cm 3 / min to 750 cm 3 / min, and most preferably 100 cm 3 / min to 300 cm 3 / min.

[0504] This flow, i.e., the flow rate, can utilize the vacuum - holding ability of the porous material 168 and can ensure sufficient liquid pickup while limiting energy consumption.

[0505] The wet cleaning device can also include a dirty liquid collection tank (not visible in Figure 33A and Figure 33B ). In such embodiments, the vacuum generator can be arranged to suck liquid from at least one dirt inlet 142A, 142B into the dirty liquid collection tank.

[0506] In such an embodiment, the dirty liquid collection tank can be arranged relative to the underpressure generator 178 in any suitable manner, for example, upstream or downstream of the underpressure generator 178.

[0507] In some embodiments, the wet cleaning device including the cleaning head 100 includes a cleaning liquid supply (not visible in Figure 33A and Figure 33B ), which is used to supply the cleaning liquid to the cleaning head 100 for delivery towards the surface to be cleaned through at least one cleaning liquid outlet 104. Such a cleaning liquid supply can include, for example, a cleaning liquid reservoir and a delivery device, such as a delivery device including a pump, for delivering the cleaning liquid to and through at least one cleaning liquid outlet 104.

[0508] The cleaning liquid supply and at least one cleaning liquid outlet 104 can be configured to provide a continuous delivery of the cleaning liquid towards the surface 218 to be cleaned.

[0509] The cleaning liquid supply and the underpressure generator 178 can be configured, for example, such that the flow rate of the cleaning liquid delivered through at least one cleaning liquid outlet 104 is lower than the flow rate provided by the underpressure generator 178 to at least one dirty inlet 142A, 142B. This helps to ensure that the surface 218 to be cleaned is not overly wetted by the cleaning liquid. For example, the flow rate of the cleaning liquid can be in the range of 20 cm 3 / min to 60 cm 3 / min, and the flow rate provided by the underpressure generator 178 can be in the range of 40 cm 3 / min to 2000 cm 3 / min, more preferably in the range of 80 cm 3 / min to 750 cm 3 / min, and most preferably in the range of 100 cm 3 / min to 300 cm 3 / min.

[0510] If a positive displacement pump is used as the underpressure generator 178, at a flow rate of 1 liter / min or 2 liters / min, such a pump may become relatively large and noisy, so a lower flow rate may help to keep the wet cleaning device relatively small, quiet and lightweight.

[0511] In principle, it is sufficient if the flow rate of the underpressure generator 178 is equal to the flow rate of the cleaning liquid provided by the cleaning liquid supply.

[0512] However, if, for example, the porous material 168 (e.g., newly attached) encounters an overflow of water, there may be a risk of a relatively significant disturbance (necessary underpressure) to the system balance. For example, with a 40 cm 3A cleaning liquid flow rate of / minute and 50 cm provided by the underpressure generator 178 3 / minute of the wet cleaning device encounters a 50 cm 3 puddle may mean that it takes about 5 minutes to suck in all the water (resulting in a 5-minute drop in underpressure, so there is a 5-minute period during which the floor remains significantly wetter (because the puddle remains spread out)). On the other hand, 250 cm provided by the underpressure generator 178 3 / minute of flow rate can reduce it to a 14-second period. A flow rate provided by the underpressure generator 178 that is higher than the flow rate of the cleaning liquid provided by the cleaning liquid supply can allow the system to recover to equilibrium faster after such a disturbance.

[0513] In Figure 33A and Figure 33B In the non-limiting example shown, the cleaning liquid is delivered, for example, from the above-mentioned cleaning liquid reservoir via the tube 268, which bifurcates to supply the cleaning liquid to the cleaning liquid outlet 104 of the cleaning liquid distribution belt 108 via the first tube 270A and to the cleaning liquid outlet 104 of the additional cleaning liquid distribution belt 124 via the second tube 270B.

[0514] In an embodiment where the wet cleaning device includes a cleaning head 100, an underpressure generator, and a cleaning liquid supply, the underpressure generator can be configured to provide suction to at least one dirt inlet 142A, 142B while (in other words, synchronously) the cleaning liquid supply supplies the cleaning liquid to at least one cleaning liquid outlet 104 and through at least one cleaning liquid outlet 104.

[0515] In Figure 33A and Figure 33B In the exemplary cleaning head 100 shown, the cleaning liquid distribution belts 108, 124 are joined to each other and to the support member 236 by the joining members 272A, 272B.

[0516] In some embodiments, the wet cleaning device includes a handle (not visible in Figure 33A and Figure 33B ) that is coupled or attachable to the cleaning head 100. Such a handle can facilitate the movement of the cleaning head 100.

[0517] In Figure 33A and Figure 33B In the non-limiting example shown, the attachment point 254 to which such a handle can be coupled includes a vertically extending slot for adjusting the height at which the attachment is provided. In this example, such an attachment point 254 is provided in each of a pair of mounting members 274A, 274B, and the handle engagement member 276 is pivotally mounted between the mounting members 274A, 274B. The handle engagement member 276 can engage the end of the handle, for example, receive the end of the handle.

[0518] In some embodiments, the handle may support or include at least a portion of a vacuum generator 178 that is fluidly connected to at least one dirt inlet 142A, 142B and / or a dirt liquid collection tank. Alternatively or additionally, at least a portion of the cleaning liquid supply, such as the cleaning liquid reservoir and / or the delivery device, may be supported by the handle or included in the handle.

[0519] In some embodiments, as Figure 33C and Figure 33D shown, the attachable member 248 (wherein the liquid pickup region PR of the porous material layer 114 is defined by a sealed attachment of the porous material layer 114 around at least one dirt inlet 142A, 142B) includes (or defines) a protruding element 252.

[0520] In Figure 33C the non-limiting example shown, the protruding element 252 includes an elastomeric material 238 on which the porous material layer 114 is disposed. In this particular example, the porous material layer 114 is sealingly attached to the support member 236 via a seal 152 (such as a heat seal).

[0521] In this way, the porous material layer 114 is sealingly attached to the (one or more) dirt inlets 142A, which in this example are defined in the support member 236 and the elastomeric material 238, i.e., bounded by the support member 236 and the elastomeric material 238. In this particular example, the dirt inlets 142A, 142B are in the form of channels extending through the support member 236 and the elastomeric material 238.

[0522] More generally, the support member 236 to which the porous material layer 114 is sealingly attached may be included in the attachable member 248. In such an example, the support member 236 may be attached to a support included in the remainder of the cleaning head 100.

[0523] The attachable member 248 may be attached to the support in any suitable manner, such as by the attachable member 248, such as the support element 236, having a ridge member that fits into a slot defined in the support, or by a support having such a ridge member that fits into a slot defined in the attachable member 248, such as defined in the support element 236.

[0524] In Figure 33C the example shown, an additional porous material layer 156 is also included in the protruding element 252. It should be noted that the process of heat-sealing the porous material layer 114 to the plastic support member 236, for example via ultrasonic welding, also causes the additional porous material layer 156 to become adhered to the porous material layer 114.

[0525] Figure 33C and Figure 33D The examples shown in Figure 33C differ from each other in that the liquid delivery support structure 154 shown in Figure 33D is defined by a surface pattern disposed on and / or in the surface of the elastomeric material 238, while

[0526] Figure 33E An exemplary separable element 244 is shown, which includes additional porous material layers 158A, 158B and cleaning liquid applicator materials 126, 128. This example has some similarities with Figure 26 the separable element 244 shown in

[0527] except that in this case the cleaning liquid applicator materials 126, 128 are mounted on the additional porous material layers 158A, 158B.

[0528] In Figure 33E it is further evident that the backing layer BL and the tufts TU included in the cleaning liquid applicator materials 126, 128. As previously described, the backing layer BL supports the tufts TU.

[0529] Figure 33F A perspective view of the cleaning head 100 is provided, which includes Figure 33C or Figure 33D the projecting element 252 / attachable member 248 shown in Figure 33E and the separable element 244 shown in

[0530] The separable element 244 can be detachably coupled to the remainder of the cleaning head 100 in any suitable manner, such as by the separable element 244, which includes a set of shoes disposed along one longitudinal side of the separable element 244 and bands disposed on opposite longitudinal sides. In this example, each of the set of shoes receives and engages a foot disposed on one longitudinal side of the remainder of the cleaning head 100, and the bands can be engaged to complementary The set of foot - shoe arrangements can help minimize unwanted movement of the separable element 244 relative to the remainder of the cleaning head 100 in the lateral and longitudinal directions.

[0531] In Figure 33F it is further apparent the label LA of the separable element 244. This label can provide attachment / detachment and / or cleaning instructions for cleaning the separable element 244 after it is separated from the remainder of the cleaning head 100.

[0532] More generally, a wet cleaning device according to one aspect of the present disclosure includes an under - pressure generator device and a cleaning head 100 having at least one dirt inlet 142A, 142B and a porous material 168, the porous material 168 including a porous material layer 114 sealingly attached to the at least one dirt inlet 142A, 142B.

[0533] The cleaning head 100 can be, for example, according to any of the embodiments described herein.

[0534] The under - pressure generator device includes an under - pressure generator 178 having an under - pressure generator outlet, the under - pressure generator 178 being activatable to provide flow from the at least one dirt inlet 242A, 242B to and through the under - pressure generator outlet, and being de - activatable to stop the flow.

[0535] In at least some embodiments, the under - pressure generator device is configured to restrict the passage of fluid from the under - pressure generator outlet towards the at least one dirt inlet 242A, 242B at least when the under - pressure generator is de - activated.

[0536] The flow rate provided by the under - pressure generator 178 can create an under - pressure in the at least one dirt inlet 142A, 142B. The porous material 168, particularly the wetted porous material 168, can help maintain the under - pressure, and liquid can be suctioned through the porous material 168 and into the (one or more) dirt inlets, as previously described.

[0537] Figure 34 An exemplary wet cleaning device 278 is schematically shown before (left - hand square), during (central square), and after (right - hand square) suctioning liquid 190 through the porous material 168. Figure 34 The left - hand square of Figure 34The central square shows the wet cleaning device 278 in operation, during which the liquid 190 (e.g., water) in contact with the porous material 168 is transported through the wet cleaning device 278 in the direction of the (multiple) dirt inlets 142A. Thus, the surface 218 to be cleaned can be dried or at least drier, but not all of the liquid 190 can be transported away from the cleaning head 100, e.g., transported to a dirty liquid collection tank included in the wet cleaning device 278 (not visible in Figure 34 ). In this non-limiting example, some of the liquid 190 can remain in the (multiple) flow paths of the liquid transport support structure 154, as shown. During operation, this liquid 190 can be beneficial as it is used to keep the porous material 168 moist, even when there is no liquid 190 on the surface 218 to be cleaned. As previously mentioned, the residual liquid 190 in the pores 192 of the porous material 168 helps maintain the underpressure. When an underpressure is maintained in the (multiple) dirt inlets 142A, the liquid 190 remains on the (multiple) dirt inlet side of the porous material 168, as shown in the central square of Figure 34 .

[0538] However, when the underpressure generator 178 is deactivated, e.g., by being turned off after using the wet cleaning device 278, the loss of underpressure can be caused by the fluid (e.g., ambient air) entering through the underpressure generator outlet. This can cause the liquid 190 to be released from the porous material 168, e.g., to drip, as shown in the right-hand square of Figure 34 .

[0539] After cleaning, e.g., wiping the surface to be cleaned, it is not desirable for the liquid 190 to be released through the porous material 168 when the underpressure generator 178 is deactivated, e.g., released back onto the surface 218 to be cleaned (or already cleaned) and / or released during the transport of the wet cleaning device 278 to its storage location.

[0540] To this end, the underpressure generator device can be configured to restrict (e.g., block) the passage of fluid (e.g., ambient air) from the underpressure generator outlet towards the (multiple) dirt inlets at least when the underpressure generator 178 is deactivated, e.g., when the underpressure generator 178 is turned off. This can mitigate the release of problematic liquid from the porous material 168, e.g., after cleaning the surface 218 to be cleaned and / or during loading the wet cleaning device in a storage area after use.

[0541] Figure 35 An exemplary wet cleaning device 278 including such an underpressure generator device 280 is schematically shown. In the left-hand square of Figure 35 , the underpressure generator 178, which is a pump in this example, is activated. This is indicated as "pump on". In Figure 35In the right - hand square, the under - pressure generator 178 is deactivated, indicated as "pump off". Contrary to the liquid leakage described above with respect to Figure 34 the fluid passage from the under - pressure generator outlet towards the (multiple) dirt inlets 142A is restricted, for example blocked, as shown by the cross 282 in Figure 35 . In this way, after the under - pressure generator 178 is deactivated, the under - pressure can be better maintained, thus reducing the release of problematic liquid from the porous material 168.

[0542] It is conceivable that at least when the under - pressure generator 178 is deactivated, any suitable means by which the under - pressure generator device 280 is configured to restrict the fluid passage from the under - pressure generator outlet towards the (multiple) dirt inlets 142A.

[0543] In some embodiments, the under - pressure generator 178 itself is configured to restrict the back - flow of fluid, such as air, from the under - pressure generator outlet in the direction of the (multiple) dirt inlets 142A when the under - pressure generator 178 is deactivated.

[0544] In some embodiments, as shown in Figure 36 , the under - pressure generator 178 is or includes a positive - displacement pump. The design of such a positive - displacement pump means that the back - flow of fluid (such as air) from the under - pressure generator outlet (in other words, the pump outlet) in the direction of the (multiple) dirt inlets 142A is inherently restricted.

[0545] Examples of such positive - displacement pumps include peristaltic pumps, diaphragm pumps, and piston pumps. Thus, the under - pressure generator 178 can include or consist of one or more of a peristaltic pump, a diaphragm pump, and a piston pump.

[0546] Referring to Figure 36 , the depicted peristaltic pump can include a compressible hose 284 between the pump / under - pressure generator inlet 286 and the pump / under - pressure generator outlet 288, which is compressed at at least one location when the peristaltic pump is deactivated. Thus, when the peristaltic pump is deactivated, the back - flow of fluid, such as air, from the pump outlet towards the (multiple) dirt inlets 142A can be restricted, for example blocked. Thus, the selection of a peristaltic pump can minimize the under - pressure loss in the (multiple) dirt inlets, thereby minimizing the release of problematic liquid through the porous material 168 to the outside of the cleaning head 100.

[0547] The peristaltic pump can, for example, include a rotatable compression - boot assembly 290 that includes at least one compression boot 292, and the rotation of the compression - boot assembly 290 and the concomitant compression of the compressible hose 284 by the at least one compression boot 292 provide the flow.

[0548] The above diaphragm pump and piston pump use a similar type of construction, where the stationary state of the pump, i.e., when the pump is deactivated, restricts the backflow from the pump outlet 288 in the direction of the (multiple) dirt inlets 142A.

[0549] In some embodiments, for example, as an alternative or supplement to the above positive displacement pump that constitutes the underpressure generator 178, the underpressure generator device 280 includes, for example, a valve assembly represented by the cross 282 in Figure 35 which is configured to restrict the passage of fluid from the underpressure generator outlet 288 towards at least one dirt inlet 142A.

[0550] In Figure 35 the non-limiting example shown, the valve assembly is configured to restrict the passage of the fluid between the underpressure generator inlet 286 and at least one dirt inlet 142A.

[0551] Alternatively or additionally, the passage of the fluid can be restricted between the underpressure generator outlet 288 and the underpressure generator inlet 186. For example, as described above with respect to the positive displacement pump, the positive displacement pump is included in or defines the underpressure generator 178.

[0552] The valve assembly can have any suitable design. In some embodiments, the valve assembly is configured to restrict the passage of the air in response to the underpressure generator 178 being deactivated. This can be considered an “active” valve that is triggered by the deactivated underpressure generator 178 to close the system (by restricting the passage of fluid from the underpressure generator outlet 288 towards the (multiple) dirt inlets 142A).

[0553] In some embodiments, the valve assembly includes a check valve that is configured to prevent the conveyance of fluid in the direction of at least one dirt inlet 142A. The check valve can be considered a “passive” valve. Such a check valve can be arranged to allow fluid, such as air and / or liquid, to flow out of the porous material 168, but prevent the fluid (such as air and / or liquid) from returning towards the (multiple) dirt inlets 142A when and after the underpressure generator 178 is deactivated. Any suitable check valve design can be envisaged, such as a ball check valve.

[0554] In a non-limiting example, an additional porous material portion made of, for example, a microfiber fabric is arranged between the porous material layer 114 and the underpressure generator outlet 288. The additional porous material portion is capable of allowing fluid flow (such as air and / or liquid) to leave the porous material layer 114, but restricts the return of fluid (such as air and / or liquid) towards the porous material layer 114 (at least) when the underpressure generator 178 is deactivated.

[0555] More generally, the underpressure generator 178 can be configured such that when the flow is provided by the (activated) underpressure generator 178, the flow rate is in the range of 40 cm 3 / min to 2000 cm 3 / min, more preferably in the range of 80 cm 3 / min to 750 cm 3 / min, and most preferably in the range of 100 cm 3 / min to 300 cm 3 / min.

[0556] Such flow, i.e., the flow rate, can utilize the underpressure holding ability of the porous material 168 and can ensure sufficient liquid pickup while limiting energy consumption.

[0557] It is reiterated that the wet cleaning device 278 can include a dirty liquid collection tank (not visible in Figure 35 and Figure 36 ) for collecting the dirty liquid, and the underpressure generator device 280 is arranged such that the flow direction and the flow through the underpressure generator outlet 288 suck the dirty liquid from at least one dirty inlet 142A into the dirty liquid collection tank. In such an embodiment, the above valve assembly can be arranged in any suitable manner relative to, for example, upstream or downstream of the dirty liquid collection tank.

[0558] In some embodiments, a sealed flow path is defined between the (multiple) dirty inlets 142A and the underpressure generator outlet 288.

[0559] This helps to maintain the underpressure.

[0560] In an alternative embodiment, fluid (such as air) can enter via one or more regions other than the underpressure generator outlet 288 and the holes 192 of the porous material 168 of the wet cleaning device 278.

[0561] However, in such an alternative embodiment, the configuration of the underpressure generator device 280 can still help to maintain the underpressure by (at least) restricting the passage of fluid from the underpressure generator outlet 288 in the direction of the dirty inlet 142A.

[0562] In some embodiments, the underpressure generator device 280 includes a valve assembly 282, such as the above valve assembly 282, which is positioned between one or more regions and the (multiple) dirty inlets 142A, thereby restricting the backflow from one or more regions towards the (multiple) dirty inlets 142A. In such an embodiment, the valve assembly 142A can, for example, also restrict the backflow from one or more regions in addition to restricting the passage of fluid from the underpressure generator outlet 288 in the direction of the (multiple) dirty inlets 142A.

[0563] More generally, a wet cleaning apparatus according to another aspect of the present disclosure includes an underpressure generating device 280 and a cleaning head 100 having at least one dirt inlet 142A, 142B and a porous material 168 covering the at least one dirt inlet 142A, 142B. In some embodiments, the porous material 168 includes a porous material layer 114 sealingly attached to the at least one dirt inlet 142A, 142B. The cleaning head 100 can be, for example, according to any of the embodiments described herein. In this aspect, the underpressure generating device 280 includes an underpressure generator 178 configured to provide a flow inside the wet cleaning apparatus for sucking fluid through the porous material 168 into the at least one dirt inlet, and the underpressure generating device 280 is configured to control the flow based on the pressure on the inner side of the wet cleaning apparatus, for example, in the at least one covered dirt inlet 142A, 142B, between the porous material 168 and the underpressure generator 178.

[0564] By controlling the flow based on the pressure on the inner side of the wet cleaning apparatus between the porous material 168 and the underpressure generator 178, the underpressure generating device 280 can advantageously control the fluid delivery through the porous material 168. In some non-limiting examples, such control can minimize foam accumulation in and downstream of the porous material 168.

[0565] In some embodiments, the underpressure generating device 280 is configured to control the flow rate such that the pressure remains at or above a predetermined pressure threshold.

[0566] By controlling the flow rate to maintain the pressure at or above a predetermined threshold (in other words, at or below an underpressure threshold), stable and efficient operation of the wet cleaning apparatus 278 can be promoted. In particular, maintaining the pressure at or above a predetermined threshold can mean that the underpressure generator 178 can operate more effectively, for example, by intermittently deactivating / disconnecting, thereby utilizing the above-described ability of the porous material 168 to help maintain an underpressure in the covered dirt inlet(s) 142A, 142B.

[0567] As previously described, control of the flow rate can also help control the humidity of the surface to be cleaned.

[0568] Figure 37A The pores 192 of the porous material layer 168, such as micropores 192, are schematically shown filled with a liquid 190, such as water. The retained liquid 190 can thus help maintain an underpressure in the dirt inlet(s) 142A, with or without a flow applied by the underpressure generator 178, as previously described.

[0569] As also explained previously, each pore 192 of the porous material 168 can have a certain burst pressure at which the surface tension of the (residual) liquid 190 residing in the pore 192 can no longer withstand the internal underpressure and gives way. When this occurs, the pore 192 is no longer effectively sealed by the liquid contained therein, but can start to convey air into the (one or more) dirt inlets 142A.

[0570] A typical pump used as the underpressure generator 178 can be, for example, a flow-driven pump or a positive displacement pump, such as a piston pump, and can move towards its maximum operating pressure, for example 20000 Pa, when the porous material 168 is blocked. The latter can be higher than the average burst pressure of the porous material 168, for example about 5000 Pa, such that the porous material 168 can start to allow air to pass through at a certain point.

[0571] Operation using, for example, pure water as the liquid 190 may cause little (if any) difficulty. However, problems may arise when the cleaning liquid 190 contains a foaming detergent. Referring Figure 37B to, the burst pores 294 can start to deliver air at the rate of the underpressure generator 178 (such as a pump), which may risk generating a relatively large amount of foam 296 that may, for example, relatively quickly flood the dirty liquid collection tank (not visible in Figure 37B ).

[0572] In a specific non-limiting example, the pump of the above-described cleaning liquid supply (not visible in Figure 37B ) delivers a cleaning liquid flow of 40 cm 3 / min. Thus, only 40 cm 3 of the cleaning liquid (such as water) may be available for pick-up. In this example, the underpressure generator 178 (such as a pump) delivers a flow rate of about 150 cm 3 / min. This combination can produce at least (150 cm 3 / min - 40 cm 3 / min =) 110 cm 3 / min of foam. For example, when a dirty liquid collection tank with a capacity of 400 cm 3 is included in the wet cleaning device 278, this can reach capacity in about 4 minutes (reach capacity in about 10 minutes at a pick-up rate of 40 cm 3 / min).

[0573] This shows that without taking remedial measures, especially when the cleaning liquid includes a water-containing detergent, rapid foam accumulation can lead to an interruption in the use of the wet cleaning device 278. Such an interruption can include frequently interrupting the cleaning to empty the dirty liquid collection tank.

[0574] Thus, the above-mentioned predetermined pressure threshold can be set, for example, to avoid reaching the burst pressure of at least some of the pores 192 (such as most or all of the pores) of the porous material 168. When using a cleaning agent, this helps to avoid operational problems related to foaming.

[0575] The pressure threshold can be set / pre-determined based on the burst pressure of the porous material 168 (as measured using the above-mentioned test device 166 and test procedure). Thus, the pre-determined pressure threshold can be set to limit the underpressure, in other words, the pressure difference between the inside between the porous material and the underpressure generator and the outside of the cleaning head 100, such as atmospheric pressure, to a value in the range of, for example, 2000 Pa to 13500 Pa, preferably 2000 Pa to 12500 Pa, more preferably 5000 Pa to 9000 Pa, and most preferably 7000 Pa to 9000 Pa.

[0576] Studies have shown that the higher the underpressure, the drier the surface to be cleaned may become, as explained earlier (see Table 1 above). This leads to the conclusion that the wet cleaning device 278 ideally operates at the burst pressure of the porous material 168.

[0577] The above studies have shown that operating at an underpressure of 5000 Pa can provide favorable surface drying results. Therefore, a working window that can prevent foaming can be defined. Table 3 provides specific non-limiting examples of the operating parameters of an exemplary wet cleaning device 278.

[0578] Cleaning liquid supply pump flow rate <![CDATA[40 cm 3 / minute]]> Flow rate delivered by underpressure generator 178 (e.g. pump) <![CDATA[150 cm 3 / minute]]> Burst pressure of porous material 168 6500 Pa Operating pressure 5000 Pa

[0579] Table 3

[0580] The above parameters can reflect that the porous material 168 can exhibit favorable surface drying ability at 5000 Pa and can only start to "burst" at 6500 Pa.

[0581] Therefore, by adjusting the pressure, in other words, by selecting the above-mentioned pressure threshold, such that the underpressure behind the porous material 168 does not reach the burst pressure of the porous material 168, foaming can be minimized or prevented.

[0582] Figure 37C The illustration shows the operating window of the wet cleaning device, especially when the wet cleaning device is started. Figure 37C The relationship between pressure and time relative to atmospheric pressure is shown.

[0583] The breaking pressure BP of the porous material 168 can be considered negative (with reference to atmospheric pressure). Thus, the pressure inside the wet cleaning device between the porous material 168 and the underpressure generator 178 can be maintained above this underpressure BP. On the other hand, if the breaking pressure of the porous material is an absolute pressure (with reference to vacuum, 0 Pa), then the pressure inside the wet cleaning device between the porous material 168 and the underpressure generator 178 can still be maintained above such an absolute pressure, in particular by a controlled flow in order to maintain the pressure at or above a predetermined threshold PT.

[0584] Figure 37C Also shown is a "safety zone" SZ at or above a predetermined threshold PT, at which threshold PT the wet cleaning device can be operated without approaching the breaking pressure BP of the porous material 168. In addition, Figure 37C Shown is an optimal operating zone OZ, at which optimal operating zone OZ the requirement of avoiding reaching the breaking pressure BP of the porous material 168 is combined with the achievement of sufficient liquid pickup from the surface to be cleaned.

[0585] More generally, controlling the flow rate based on the pressure in at least one covered dirt inlet 142A can be achieved in any suitable manner. In some embodiments, for example Figure 38 in the embodiment shown, the underpressure generator device 280 includes a sensor 180 and a controller 298, the sensor 180 being arranged to sense a measured value of the pressure on the inside of the wet cleaning device between the porous material 168 and the underpressure generator 178, and the controller 298 being configured to control the underpressure generator 178 to provide a flow rate based on the sensed pressure measurement.

[0586] The controller 298, such as a microcontroller, can receive a sensor signal from the sensor 180, as Figure 38 shown by arrow 300 in, and send a control signal 302 to the underpressure generator 178 based on the sensor signal.

[0587] For example, the control signal 302 can trigger the underpressure generator 178 to activate to provide flow or deactivate to stop flow. Alternatively or additionally, the control signal 302 can increase or decrease the flow rate according to the sensor signal 300. The deactivation or reduction of the flow rate provided by the underpressure generator 178 in this way can contribute to reducing the power consumption of the wet cleaning device 278. This can contribute to maintaining battery power in examples where the wet cleaning device is battery-powered / battery-operable, and thereby increase the runtime.

[0588] As previously mentioned, controlling the flow rate can also contribute to controlling the humidity of the surface to be cleaned.

[0589] In some embodiments, the controller 298 is configured to control the flow provided by the underpressure generator 178 such that the pressure on the inner side between the porous material 168 and the underpressure generator 178 of the wet cleaning device is maintained at or above the aforementioned predetermined pressure threshold. In a non-limiting example, if the sensed pressure measurement indicates that the pressure is below the predetermined pressure threshold, the underpressure generator 178 can control the underpressure generator 178 to disable to stop or reduce the flow.

[0590] In a non-limiting example, the controller 298 (e.g., including a proportional-integral controller or in the form of a proportional-integral controller) is configured to compare the sensed measurement of the pressure with a desired operating pressure (e.g., set with reference to the burst pressure of the porous material 168, as described above), and control the underpressure generator 178 based on this comparison.

[0591] In some embodiments, the sensor 180 is arranged to sense the measurement of the pressure in at least one of the following: the cavity 150 between the porous material 168 and at least one dirt inlet 142A, and the tube 144A (or tubes 144A, 144B) connecting at least one dirt inlet 142A to the underpressure generator 178.

[0592] Sensing the pressure measurement in the cavity 150 can be particularly advantageous because the flow can be tuned more directly to the characteristics of the porous material 168 during use.

[0593] The sensor 180 is arranged such that the pressure measurement sensed in the (multiple) tubes 144A, 144B can provide a relatively straightforward way to incorporate the sensor 180 into the wet cleaning device.

[0594] In embodiments where the underpressure generator 178 is arranged downstream of the dirty liquid collection tank, the sensor 180 can also be located in the dirty liquid collection tank. In this case, for example, the height of the dirty liquid collection tank arranged on or in the handle may generate noise (dP = H * cos(α) * ρ * g, where H is the height of the dirty liquid collection tank in the vertical position, and α is the angle of the handle relative to the vertical direction). However, this noise can be compensated by including an angle sensor (e.g., an accelerometer) in the sensor 180.

[0595] More generally, the sensor 180 can be any suitable type of sensor as long as the sensor is capable of sensing the measurement of the pressure on the inner side between the porous material 168 and the underpressure generator 178 of the wet cleaning device. For example, the sensor includes a pressure sensor, such as a microelectromechanical system (MEMS) pressure sensor.

[0596] In some embodiments, for example Figure 39In the illustrated embodiment, the underpressure generator device 280 includes a mechanical regulator 304 configured to control the flow based on the pressure on the inner side between the porous material 168 and the underpressure generator 178 of the wet cleaning device.

[0597] The mechanical regulator 304 can for example include valves 306, 308 arranged to control the fluid communication between the underpressure generator 178 and at least one soiled inlet 142A according to the pressure in at least one covered soiled inlet 142A.

[0598] In Figure 39 In the non - limiting example shown, the valves 306, 308 include a valve seat 306 and a valve member 308 configured to assume an initial position and a closed position. In the initial position, the valve member 308 is separated from the valve seat 306 to allow fluid communication between the underpressure generator 178 and at least one soiled inlet 142A. In the closed position, the valve member 308 abuts against the valve seat 306 to restrict the fluid communication between the underpressure generator 178 and at least one soiled inlet 142A.

[0599] In some embodiments, the valves 306, 308 are configured such that when the pressure is below the above - mentioned predetermined pressure threshold, the valve member 308 is caused to move against the valve seat 306 by the pressure in at least one covered soiled inlet 142A.

[0600] The valve member 308 can for example be in the form of a flexible rubber membrane which assumes a flat profile in the initial position and is thus spatially removed from the valve seat 306 when there is no underpressure in the covered soiled inlet(s) 142A. After starting the underpressure generator 178 (e.g. a pump), an underpressure can be generated in the covered soiled inlet(s) 142A and in the mechanical regulator 304. The underpressure can act on the exposed surface of the rubber membrane in the mechanical regulator 304, which can thus start to deflect inwards in the direction of the valve seat 306.

[0601] In this non - limiting example, the threshold pressure can be set / pre - determined by the distance between the flexible rubber membrane and the valve seat 306. The greater the distance, the higher the underpressure (or equivalently, the lower the pressure) in the covered soiled inlet(s) 142A required to deform the rubber membrane to contact the valve seat 306.

[0602] Once the underpressure reaches the level at which the rubber membrane contacts the valve seat, the fluid communication between the underpressure generator 178 and the porous material 168 can be removed, thereby preventing the underpressure from reaching a higher level than that set by the mechanical regulator 304. The underpressure generator 178 can continue to operate at the same rate towards its maximum operating underpressure. When the underpressure in the covered dirt inlet(s) 142A decreases, the flexible membrane can move back towards the above-mentioned flat state, thereby opening the valves 306, 308 and allowing the underpressure generator 178 to restore the desired underpressure level.

[0603] In another non-limiting example, the mechanical regulator 304 includes a switch and a deflectable member, the actuation of the switch controlling the underpressure generator 178, and the deflectable member being, for example, a diaphragm configured to actuate the switch in response to pressure.

[0604] Such a mechanical regulator, in this case an electromechanical regulator, can be configured such that when the pressure is, for example, at or above a predetermined pressure threshold, the switch is actuated by the diaphragm, for example to deactivate the underpressure generator 178.

[0605] Such a switch-diaphragm arrangement can provide a simple and inexpensive way to control the flow based on pressure without the need for an additional controller, such as a microcontroller.

[0606] In some embodiments, as Figure 40 and Figure 41 shown, the underpressure generator 178 itself includes a pump configured to control the flow in response to the pressure in at least one covered dirt inlet 142A.

[0607] Such a pump can be considered a pressure-limiting pump. A pressure-limiting pump is capable of generating a certain pressure difference across the tube to which it is connected. In principle, the pump pressure can be tuned to the pressure required for the porous material 168 covering the dirt inlet(s) 142A.

[0608] The pressure-limiting pump can include or be, for example, a centrifugal pump. The pump, such as a centrifugal pump, can be or include a liquid pump. Such a liquid pump can, for example, be arranged between the dirt inlet 142A and the dirty liquid collection tank 310.

[0609] In Figure 40 the non-limiting example shown, the underpressure generator 178, such as a centrifugal pump and / or a liquid pump, is arranged in the cleaning head 100.

[0610] Alternatively, the pump, such as a centrifugal pump, can be or include an air pump. Such an air pump can, for example, be arranged downstream of the dirty liquid collection tank 310.

[0611] It should be noted that the dirty liquid collection tank 310 can be arranged at a specific height 312 on the handle, for example 0.5 m. Therefore, an additional head may be required:

[0612] P = h * ρ * g = 0.5 * 1000 * 9.81 to 5000 Pa

[0613] When considering the position of the handle, including the position where the handle lies flat on a horizontal surface 218 to be cleaned, such as a floor surface (where the water head becomes zero), the pressure change on the porous material 168 can be equal to its operating pressure. The latter can be solved by attaching the pipe 144A at a fixed height relative to the floor, regardless of the position of the handle, for example, by directly attaching (a part of) the dirty liquid collection tank 310 to the porous material 168.

[0614] Figure 41 The wet cleaning device 278 is schematically shown, where a vacuum generator 178, a pressure-limiting air pump (such as a centrifugal air pump), is used to regulate the pressure. This can provide the starting benefit for the Figure 40 shown example, because the pump can always operate using air, thus ensuring that the pump can generate the required vacuum (the porous material 168 is completely dry) at startup.

[0615] In some embodiments, the vacuum generator 178, regardless of its design, is configured such that when a flow rate is provided, the flow rate is in the range of 40 cm 3 / minute to 2000 cm 3 / minute, more preferably in the range of 80 cm 3 / minute to 750 cm 3 / minute, and most preferably in the range of 100 cm 3 / minute to 300 cm 3 / minute.

[0616] Such a flow rate, i.e., flow velocity, can utilize the vacuum holding capacity of the porous material and can ensure sufficient liquid pickup while limiting energy consumption, as described above.

[0617] More generally, the wet cleaning device 278 can be or include, for example, a wet mopping device, a window cleaner, a sweeper, or a wet vacuum cleaner, such as a canister, stick, or upright wet vacuum cleaner.

[0618] In certain non-limiting examples, the wet cleaning device 278 is a battery-powered (or battery-powered-capable) wet cleaning device, such as a battery-powered (or battery-powered-capable) wet mopping device, where the underpressure generator 178 (e.g., a pump) is powered (or powerable) by a battery electrically connected (or electrically connectable) thereto. Due to the above-described power consumption reduction effect, this example is specifically mentioned, and the power consumption reduction effect can be provided by the porous material 168 covering the (multiple) dirt inlets 142A, 142B, and the suction of the underpressure generator 178 is provided to the dirt inlets 142A, 142B.

[0619] Figure 42 An exemplary wet cleaning device 278 in the form of a wet vacuum cleaner is schematically shown. In this non-limiting example, the wet cleaning device 278 includes the above-described dirt liquid collection tank 310 and the cleaning liquid reservoir 313. The cleaning head 100 included in the wet vacuum cleaner can move on the surface 218 to be cleaned, assisted in this example by wheels 314 included in the wet vacuum cleaner.

[0620] In some examples, the wet cleaning device 278 can be or include a robotic wet vacuum cleaner or a robotic wet mopping device, which is configured to autonomously move the cleaning head 100 on the surface to be cleaned (e.g., the surface of a floor).

[0621] Figure 43 An exemplary wet cleaning device 278 in the form of a robotic wet vacuum cleaner is schematically shown. The robotic wet vacuum cleaner can move autonomously on the surface 218 to be cleaned, for example, by automatic control of the wheels 314.

[0622] During the autonomous movement of the robotic wet vacuum cleaner, the cleaning liquid stored in the cleaning liquid reservoir 313 can be delivered to the surface to be cleaned, and the liquid can be picked up via the covered (multiple) dirt inlets 142A of the cleaning head 100 and collected in the dirt liquid collection tank 310. The underpressure generator 278 / underpressure generator device 280 and / or the cleaning liquid supply can also be automatically controlled.

[0623] By studying the drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement other variations of the disclosed embodiments when practicing the claimed invention. 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 fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A wet cleaning device (278), comprising: A cleaning head (100) having at least one dirt inlet (142A, 142B) and a porous material (168) covering the at least one dirt inlet; and An underpressure generator device (280) comprising an underpressure generator (178) configured to provide a flow rate inside the wet cleaning device for drawing fluid through the porous material into the at least one dirty inlet, wherein the underpressure generator device is configured to control the flow rate based on a pressure on the inside of the wet cleaning device between the porous material and the underpressure generator, The underpressure generator device (280) is configured to control the flow rate so that the pressure is maintained at or above a predetermined pressure threshold, and the predetermined pressure threshold is determined based on a rupture pressure of the porous material (168).

2. The wet cleaning device (278) according to claim 1, wherein the predetermined pressure threshold is set to limit the pressure difference between the inside of the wet cleaning device and the outside of the cleaning head to a value in the range of 2000 Pa to 13500 Pa.

3. The wet cleaning device (278) of claim 1, wherein the undervoltage generator device (280) comprises: a sensor (180) arranged to sense a measurement of the pressure; as well as A controller (298) is configured to control the underpressure generator (178) to provide the flow rate based on the sensed measurement of the pressure.

4. The wet cleaning device (278) of claim 2, wherein the undervoltage generator device (280) comprises: a sensor (180) arranged to sense a measurement of the pressure; as well as A controller (298) is configured to control the underpressure generator (178) to provide the flow rate based on the sensed measurement of the pressure.

5. A wet cleaning device (278) according to claim 3, wherein the sensor (180) is arranged to sense a measured value of the pressure in at least one of the following: a cavity (150) between the porous material (168) and the at least one dirty inlet (142A, 142B); and a tube connecting the at least one dirty inlet (142A, 142B) to the underpressure generator (178).

6. A wet cleaning device (278) according to claim 4, wherein the sensor (180) is arranged to sense a measured value of the pressure in at least one of the following: a cavity (150) between the porous material (168) and the at least one dirty inlet (142A, 142B); and a tube connecting the at least one dirty inlet (142A, 142B) to the underpressure generator (178).

7. The wet cleaning device (278) according to any one of claims 1 to 6, wherein the underpressure generator device (280) comprises a mechanical regulator (304) configured to control the flow rate based on the pressure.

8. The wet cleaning device (278) of claim 7, wherein the mechanical regulator (304) comprises a valve arranged to control fluid communication between the underpressure generator (178) and the at least one dirty inlet (142A, 142B).

9. A wet cleaning device (278) according to claim 8, wherein the valve includes a valve seat (306) and a valve member (308), the valve member being configured to adopt an initial position and a closed position, in which the valve member is separated from the valve seat to allow fluid communication between the underpressure generator and the at least one dirty inlet (142A, 142B), and in which the valve member abuts against the valve seat to limit fluid communication between the underpressure generator and the at least one dirty inlet.

10. A wet cleaning device (278) according to claim 9, wherein the valve is configured so that when the pressure is below the predetermined pressure threshold, the valve member (308) moves against the valve seat (306) caused by the pressure in the at least one covered dirty inlet (142A, 142B).

11. A wet cleaning apparatus (278) according to any one of claims 1 to 6 and 8 to 10, wherein the underpressure generator (178) comprises a pump configured to control the flow rate in response to the pressure in the covered dirty inlet.

12. The wet cleaning device (278) of claim 11, wherein the pump comprises a centrifugal pump.

13. The wet cleaning device (278) of claim 11, wherein the pump comprises a liquid pump.

14. The wet cleaning device (278) of claim 13, wherein the liquid pump is arranged in the cleaning head (100) or in a handle coupled to the cleaning head.

15. A wet cleaning device (278) according to any one of claims 1 to 6, 8 to 10 and 12 to 14, comprising a dirty liquid collection tank (310) for collecting liquid, the underpressure generator device (280) being arranged so that the flow draws liquid from the at least one dirty inlet (142A, 142B) to the dirty liquid collection tank.

16. The wet cleaning device (278) according to claim 11 comprises a dirty liquid collection tank (310) for collecting liquid, the underpressure generator device (280) being arranged so that the flow draws liquid from the at least one dirty inlet (142A, 142B) to the dirty liquid collection tank, wherein the pump comprises an air pump arranged downstream of the dirty liquid collection tank (310).

17. The wet cleaning device (278) of any one of claims 1 to 6, 8 to 10, 12 to 14, and 16, wherein the porous material (168) comprises a porous material layer (114) sealingly attached to the at least one dirty inlet (142A, 142B).

18. A wet cleaning device (278) according to any one of claims 1 to 6, 8 to 10, 12 to 14 and 16, wherein the cleaning head (100) includes at least one cleaning liquid outlet (104), and the cleaning liquid can be delivered through the at least one cleaning liquid outlet (104), and wherein the wet cleaning device includes a cleaning liquid supply, the cleaning liquid supply includes a cleaning liquid reservoir (313) for containing the cleaning liquid, and the cleaning liquid reservoir can be fluidically connected to or in fluid communication with the at least one cleaning liquid outlet.

19. A wet cleaning device (278) according to any one of claims 1 to 6, 8 to 10, 12 to 14 and 16, wherein the wet cleaning device is a wet mopping device, and / or wherein the undervoltage generator (178) is configured such that when providing a flow rate, the flow rate is between 15 cm 3 / min to 2000cm 3 / minute range.

20. The wet cleaning device (278) according to any one of claims 1 to 6, 8 to 10, 12 to 14 and 16, wherein the wet cleaning device is a wet mopping device, and / or wherein the undervoltage generator (178) is configured such that when providing a flow rate, the flow rate is 40 cm / s. 3 / min to 2000cm 3 / minute range.

21. A wet cleaning device (278) according to any one of claims 1 to 6, 8 to 10, 12 to 14 and 16, wherein the wet cleaning device is a wet mopping device, and / or wherein the undervoltage generator (178) is configured such that when providing a flow rate, the flow rate is between 80 cm 3 / min to 750cm 3 / minute range.

22. The wet cleaning device (278) according to any one of claims 1 to 6, 8 to 10, 12 to 14 and 16, wherein the wet cleaning device is a wet mopping device, and / or wherein the undervoltage generator (178) is configured such that when providing a flow rate, the flow rate is 100 cm / s. 3 / min to 300cm 3 / minute range.

23. The wet cleaning device (278) according to any one of claims 1 to 6, 8 to 10, 12 to 14 and 16, wherein the undervoltage generator (178) is configured to provide a pressure less than or equal to 2000 cm 3 / min flow rate through the porous material (168).

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