Method for operating a water-conducting household appliance with a primary and a secondary filter device and water-conducting household appliance suitable therefor

Abstract

The invention relates to a method for operating a water-conducting household appliance 1, comprising a primary filter device 22 arranged in a drain channel 23 of the household appliance 1, said device comprising a rotatable filter element 24 for separating a mass 25 containing microplastic particles from an aqueous liquid 7, a discharge pump 18 arranged upstream of the primary filter device 22 in the flow direction, and a secondary filter device 4 which is fluidly connectable to the primary filter device 22 via a conveying line 26, wherein, in a rinsing phase of the primary filter device 22, the rotatable filter element 24 is rotated such that a flow is generated in the aqueous liquid 7 in the direction of the secondary filter device 4. The invention also relates to a water-conducting household appliance suitable for carrying out this method.

Description

[0001] The invention relates to a method for operating a water-conducting household appliance with a primary and a secondary filter device and to a water-conducting household appliance suitable therefor.

[0002] The problem of microplastics is of great importance, as their distribution has been observed even in remote ocean regions and among marine organisms. Microplastics can be generated or spread in various ways, for example, through tire wear, through the use of cleaning products and cosmetics, and even during the treatment of laundry. For example, laundry appliances such as washing machines, washer-dryers, and dryers release small particles, particularly lint and other plastic particles, from the laundry being treated.

[0003] The development and integration of a technical system for cleaning the wastewater of microplastic particles in washing machines is therefore of great importance. The wastewater or exhaust air from laundry treatment machines should be able to be cleaned of microplastic particles, ideally over multiple wash cycles without customer intervention. Work is underway on retention systems for microplastic emissions.

[0004] In the filter device of a water-using household appliance, referred to herein as a primary filter device, wastewater from the water-using household appliance, in particular a washing machine or washer-dryer, is filtered before it leaves the appliance. Microplastics and all other substances such as lint or small particles that a user has washed in their laundry are filtered out after the washing process in the so-called pumping or dewatering process by being retained on a generally finely perforated filter surface.

[0005] Against this background, the object of the present invention was to provide a method for operating a water-conducting household appliance, comprising a primary filter device arranged in a drain channel of the household appliance, a discharge pump arranged upstream of the primary filter device in the flow direction, and a secondary filter device that is fluidically connectable to the primary filter device, with which small parts generated in a treatment process in the water-conducting household appliance can be transported efficiently and safely from the primary to the secondary filter device. The object of the invention was also to provide a water-conducting household appliance suitable for carrying out this method.

[0006] This object is achieved according to this invention by a method for operating a water-conducting household appliance and a water-conducting household appliance suitable for carrying out this method, having the features of the respective independent patent claims. Preferred embodiments of the method according to the invention and of the water-conducting household appliance according to the invention are listed in the dependent patent claims, wherein preferred embodiments of the method according to the invention correspond to preferred embodiments of the household appliance according to the invention, even if this is not explicitly mentioned herein.

[0007] The subject of the invention is therefore a method for operating a water-conducting household appliance, comprising a primary filter device arranged in a drain channel of the household appliance with a rotatable filter element for separating a mass containing microplastic particles from an aqueous liquid, a discharge pump arranged upstream of the primary filter device in the flow direction, and a secondary filter device which is fluidically connectable to the first filter device via a conveying line, wherein in a rinsing phase of the primary filter device the rotatable filter element is rotated in such a way that a flow in the direction of the secondary filter device is generated in the aqueous liquid.

[0008] “Fluidically connectable” means that the delivery line can, if necessary, also be closed by a closing device, e.g. a valve, for a specified period of time.

[0009] According to the invention, due to the rotation of the rotatable filter element, which is driven by a so-called filter motor, also called drive motor, all substances filtered out on the cylindrical surface of the filter element, in particular also small parts located in front of the filter element, are flushed to the secondary filter device.

[0010] Due to its design, the entire microplastic filter (MPF) system only allows a certain geometric dimension of particles (particles and larger parts) due to the necessary system gaps between moving and stationary parts. Larger particles can be filtered out using a separate large-parts filter if necessary. This, as well as the filtering out of any small parts, must always take place upstream of the MPF system in the direction of flow, upstream of the lye discharge pump, referred to herein in particular as the discharge pump.

[0011] In any case, according to the invention, these small parts and possibly larger parts must be filtered out. All small parts that can pass through a large parts filter, if present, must then be reliably conveyed by the MPF system into the secondary filter device without causing filter blockages or blockages in the flow cross-section during the regeneration process of the primary filter system or during transport to the secondary filter device. Small parts within the meaning of this invention are, in particular, parts with dimensions in the range of 1 mm to several centimeters, especially in the range of 1 mm to 3 cm. Examples of these are coins, hair clips, paper clips, and buttons.

[0012] According to the invention, the filter element is particularly preferably a cylindrical filter element, and the primary filter device is configured to rotate the cylindrical filter element in such a way that the mass containing microplastic particles deposited on the filter element is centrifuged off and, together with any small particles that may have accumulated in front of the filter element, is conveyed through the conveying line into the secondary filter device by means of a suitably generated, sufficiently high flow. Larger particles can be collected in advance in an optionally used large particles trap.

[0013] The rotatable filter element therefore preferably has a cylindrical outer surface. For example, in a cylindrical filter element, a cylindrical filter surface can surround a cylindrical filter interior, and an aqueous liquid to be filtered can flow radially into the cylindrical filter interior and exit it again in an axial direction.

[0014] There is generally a drive motor for the rotating filter element, which is used for the backwashing process of the primary filter device. During this backwashing process, the aqueous fluid flows from the inside to the outside through the filter surface, i.e., the surface of the filter element.

[0015] A pump wheel, preferably arranged on the rotatable filter element of the primary filter device, ensures that the backwashed aqueous liquid containing lint and microplastics is conveyed to the secondary filter device.

[0016] According to the invention, the filter element used, e.g. a cylindrical filter element, is preferably to have a mesh size in the range from 10 to 300 µm, preferably in the range from 30 to 70 µm and very particularly preferably in the range from 40 to 60 µm, for example 50 µm.

[0017] According to the invention, it is generally not necessary to replace the primary filter device. Instead, a user of the water-using household appliance will generally clean or replace the secondary filter device directly. Cleaning the secondary filter device will depend on its design.

[0018] In one embodiment, a filter element of the secondary filter device must be replaced regularly to ensure the safe regeneration or functioning of the primary filter device so that the pumping out of the aqueous liquid is not disturbed or excessively influenced by an excessive pressure loss at the primary filter device.

[0019] In general, the secondary filter device will be designed and positioned to be easily accessible to a user. Therefore, the secondary filter device is preferably located next to or in a dispenser drawer. This can be achieved if the water-using household appliance is a washing machine or a washer-dryer. In this case, it is again advantageous for the dispenser drawer to be connected to the secondary filter device. However, the secondary filter device does not necessarily have to be located in the dispenser drawer. This position is, however, suitable due to its good accessibility for a user.

[0020] According to the invention, it is particularly preferred if the secondary filter device is arranged behind the dispenser tray.

[0021] The dispenser tray is used in particular for dispensing detergents or other treatment agents into a tub of a water-conducting household appliance, which is preferably designed as a laundry treatment appliance. If this is the case, the dispenser tray is preferably connected to the secondary filter device. The dispenser tray and secondary filter device can form a one-piece component, which can be produced, for example, by injection molding. Alternatively, however, the dispenser tray and secondary filter device can also be detachably connected to one another, e.g. by snapping into place. In the case of a washing machine or a washer-dryer, it is further preferred according to the invention for the secondary filter device to be arranged behind the dispenser tray. This means that a user of the water-conducting household appliance can first pull out the dispenser tray.If the induction bowl and secondary filter device are connected, both can be pulled out together.

[0022] The conveying line between the primary filter device and the secondary filter device can be designed in various ways. A hose is generally used as the conveying line.

[0023] The ability to convey small parts through a given cross-section of the conveying line or hose from the primary to the secondary filter device depends on three main factors: a) Mass of the small parts, which, depending on their volume, describes the static buoyancy force in the water as positive or negative, i.e. their density, b) precise geometric dimensions of the small parts, in particular their narrowest side, which offers the smallest surface area for the flow to be transported further towards the secondary filter device in terms of dynamic buoyancy, c) flow velocity, also with regard to the determination of the dynamic buoyancy force in relation to or as a difference to the sinking velocity in the water, d) Orientation of the conveyor line in the room, since gravity also plays a role, the worst case would be if particles have to be transported from bottom to top.

[0024] In the method according to the invention, the flow velocity of the aqueous liquid between the primary and the secondary filter device is increased at least briefly, for example by at least 10% compared to the situation in which the backwashing of the primary filter device occurs by rotation of the primary filter device alone.

[0025] The method according to the invention can be carried out in different ways. For example, the method according to the invention can be carried out as a cleaning sequence during the execution of a washing program. However, the method according to the invention can also be carried out as a separate cleaning program.

[0026] In a preferred embodiment, the method according to the invention is carried out after cleaning or replacing the secondary filter device. A new filter without lint deposits presents significantly lower hydraulic resistance than a clogged filter. This increases the flow rate for the aqueous liquid because there is a lower pressure drop across the filter. The smaller the pressure drop across the secondary filter device, the higher the pump flow rate and thus the flow velocity, which is largely responsible for transporting the small particles.

[0027] The user of the water-using household appliance can change the filter and communicate this information to a control unit of the water-using household appliance. However, the water-using household appliance can also use sensors to detect that a filter change has just taken place and that a cleaning sequence is now due, without the user having to communicate this information to the control unit.

[0028] Furthermore, the control device can remind the user of the need to change or clean the secondary filter device, for example by counting or recording the number of wash cycles or regeneration cycles of the primary filter device.

[0029] Irrespective of this, it is desirable that during the implementation of the method according to the invention the rotatable filter element is completely in the aqueous liquid, i.e. a high water level is realized in the water-conducting household appliance, so that the rotatable filter element can be operated for a long time without the flow breaking off because the primary filter device and possibly also the lye emptying pump are ventilated too early.

[0030] Furthermore, the higher the water level, the lower the pump head in the general case where the secondary filter device is higher than the primary filter device, i.e., the height difference between the water level and the secondary filter device. The differential pressure required by the rotating filter element acting as a pump is then lower, increasing the flow rate at a constant power input. If the water level in the device could be set to the level of the secondary filter device, the head required to be overcome by the rotating filter element acting as a pump would be zero. The pump would then only have to overcome the pressure loss due to the flow-related pressure drops.

[0031] In addition, water can be simultaneously admitted through the inlet valves of the household appliance to regenerate the primary filter device or to transport filtered particles and small parts to the secondary filter device in order to keep the water level as high as possible in order to maximize the flow rate.

[0032] The generation of a high water level uses, where possible, a washing process condition in which, due to the washing process technology, a high water level already prevails in the tub of a preferably used washing machine, as is explicitly intended for wool programs, for example.

[0033] In the method according to the invention, it is further advantageous that the primary filter motor, i.e. the motor driving the rotating filter element, is briefly switched on and off. Without generating a significant flow rate to the secondary filter device, water is constantly moved in the primary filter device, which is intended to loosen the blockage on the filter element and transport small particles towards the secondary filter device. Subsequently, a short, powerful pulse at full pump power through the rotating filter element is sufficient to transport the small particles and other particles to the secondary filter device. This minimizes the water volume required to transport the small particles to the secondary filter device and enables reliable foreign body transport.

[0034] In a preferred embodiment of the method according to the invention, the discharge pump is operated temporarily, but not during the entire operation of the drive motor, in addition to rotating the primary filter device. This leads to an additional pressure increase, increases the total flow rate, and thus enables maximization of the flow velocity for transporting the small parts. A portion of the discharge pump's volume flow will possibly continue to be pumped from the household appliance into the sewage system via the drain hose, even if this is not preferred according to the invention. However, a partial volume flow will pass from the primary to the secondary filter device, thus increasing the pumping effect of the primary filter device.The pump flow rate of the discharge pump, which is intended to pump the water out of the device, is also referred to as the pumping flow rate, while the liquid flow generated in the primary filter device is also referred to as the primary filter flow rate.

[0035] The exact division of the volume flow into the partial volume flow that leaves the device through the drain hose and the part that flows from the primary to the secondary filter device will be adjusted according to the hydraulic resistances of the two paths.

[0036] The goal of all measures is to keep the flow rate from the primary filter device to the secondary filter device as high as possible for as long as possible to ensure the safe transport of foreign bodies, especially small particles, to the secondary filter device. This increases the likelihood of even foreign bodies with high density and a relatively small surface area being transported to the secondary filter device.

[0037] In addition, a user of the water-conducting household appliance can, if necessary, contribute by inserting special filters in the secondary filter device that are optimized for cleaning and have a significantly reduced pressure loss and are equipped with a larger filter passage area and / or a larger filter mesh size.

[0038] In a preferred embodiment of the method according to the invention, the secondary filter device is therefore designed to have a secondary filter with a particularly low hydraulic resistance, so that microplastics are generally allowed to pass through and can be circulated in the household appliance. Such a secondary filter is also referred to herein as a special secondary filter.

[0039] This is achieved, in particular, by using a mesh or filter bag with a correspondingly large mesh size and / or with a particularly high filter area penetration ratio. A large mesh size results in low hydraulic backpressure, allowing small particles to be pumped more easily from the primary filter device to the secondary filter device. The primary purpose is to capture small particles during a specific cleaning program. With this design, small particles can be transported relatively quickly to the secondary filter device, where they can be removed by a user of the water-using household appliance.

[0040] This mesh size is larger than the size of the microplastic particles to be retained. However, with this design, the microplastic particles that are no longer filtered out remain in the water-carrying household appliance and cannot enter the wastewater, as they are essentially only circulated within the household appliance, meaning they only circulate and do not leave the appliance.

[0041] Instead of a special filter bag with a large mesh size, the induction bowl itself or an additional component can be equipped with a correspondingly coarse-mesh grid. This additional grid allows the grid structure to be further reduced to accommodate the small particles to be collected.

[0042] In this case, the method according to the invention can also be carried out without a secondary filter bag. The control device generally present in the water-conducting household appliance can then be designed to allow the method according to the invention to be carried out even without a secondary filter bag. In this embodiment, a user of the appliance can remove collected small parts, for example, from a tray belonging to the secondary filter device near or in the dispenser tray, without having to open a secondary filter bag.

[0043] In an alternative preferred embodiment, the secondary filter device is designed such that it has an openable secondary filter bag that can be opened by a user of the household appliance so that foreign bodies, in particular small parts, can be removed, if necessary by washing out the secondary filter bag. This means that the special filter bag can be cleaned and reused again and again. This works best if a user of the household appliance can open the filter bag and rinse it under the tap. The mesh size must also be selected to be large enough that microplastic particles are not retained by the secondary filter bag. This prevents the flow rate of the aqueous liquid from being reduced while minimizing the filter surface area being covered by foreign bodies, and this prevents microplastic particles from entering the sewage system when rinsing under the tap.

[0044] However, the filter bag does not have to be openable. The filter bag can be completely removed as part of the secondary filter device. Opening the secondary filter device is preferably done implicitly by pulling out a dispensing tray, since at least its rear part is preferably functionally part of the secondary filter device.

[0045] Instead of or in addition to this, a secondary filter bag with a small mesh size, which can capture not only small particles but also microparticles, can also be used in the method according to the invention. However, the hydraulic backpressure can be relatively high, which is disadvantageous for pumping small particles from the primary to the secondary filter device. Since a user must change the secondary filter device during normal operation, depending on the fill level with removed filter linings, the small particles are thus removed from the virtually closed secondary filter device.

[0046] The method according to the invention therefore particularly preferably enables a combined use of normal and special secondary filter bags.

[0047] Preferably, in the method according to the invention, the secondary filter device used is recognized and the method is adapted accordingly. The secondary filter can be coded accordingly for this purpose. Furthermore, the recognition of normal and special secondary filter bags by the control device of the household appliance, e.g. based on the pressure losses across the filter detected by a pressure sensor or coding of the filters (e.g. using RFID; however, other coding options such as color are also possible), could initiate the start of a cleaning program. As mentioned, different secondary filters or secondary filter bags can be used depending on the intended use. By using, for example, an RFID chip that is read by the control device of the household appliance, a user can determine which type of filter bag is used.

[0048] Furthermore, the shape of the filter, in particular the hard structure of the inlet opening, can be designed in such a way that corresponding sensors in the device (tactile, optical, capacitive) can detect this specific shape and thus this specific filter.

[0049] According to the invention, various secondary filter devices can be combined. As already discussed, when using a secondary filter with a large mesh size, microparticles are passed through the secondary filter and are generally circulated in the water-conducting household appliance. If a secondary filter with a sufficiently small mesh size is then used, microparticles can also be captured. A filter bag filled with microparticles can then be removed and disposed of by a user.

[0050] The invention further relates to a water-conducting household appliance, comprising a control device, a primary filter device arranged in a drain channel of the household appliance, said device comprising a rotatable filter element for separating a mass containing microplastic particles from an aqueous liquid, a discharge pump arranged upstream of the primary filter device in the flow direction, and a secondary filter device which is fluidly connectable to the primary filter device via a conveying line, wherein a method described herein can be carried out in the water-conducting household appliance. In particular, a method can be carried out in the water-conducting household appliance according to the invention in which, during a rinsing phase of the primary filter device, the rotatable filter element is rotated such that a flow is generated in the aqueous liquid in the direction of the secondary filter device.Details of the water-conducting household appliance are therefore explained in more detail above in the description of the method according to the invention.

[0051] The water-based household appliance is preferably selected from the group consisting of a washing machine and a washer-dryer. The aqueous liquid to be filtered to remove microplastic particles is generally the washing solution used in a textile washing process.

[0052] If the water-conducting household appliance according to the invention is a washing machine or washer-dryer, it generally also has a drum rotatably mounted in a tub for holding laundry items, as well as a water supply device. The latter can, for example, be a valve-controlled fresh water connection, with the valve preferably being controllable by the control unit.

[0053] The invention offers numerous advantages. It enables the operation of the water-conducting household appliance with improved, more efficient use of the filter devices. Furthermore, the invention enables the filter motor, i.e., the drive motor for the filter element, to be designed for the optimal operating point during normal operation, thus achieving optimum space, performance, and cost.

[0054] According to the invention, the basic design of the pump unit of the primary filter device, in particular the motor size and the performance class of the electronic motor control, can be based on the normal load of the primary filter device caused by microplastics and lint. This allows the primary filter device to be optimized in terms of installation space and cost, and there is no need to maintain a higher performance for the rather rare case in which small particles enter the primary filter device.

[0055] The invention is illustrated below with reference to a non-limiting embodiment of a second filter device usable according to the invention and a water-conducting household appliance according to the invention, in this case a washing machine. Reference is made to the Fig. 1 to 3.

[0056] Fig. Figure 1 shows, in a non-limiting embodiment, a washing machine 1 as an example of a water-conducting household appliance according to the invention. The washing machine 1 of Fig. 1 comprises a tub 2 in which a drum 3 is rotatably mounted and driven by a drive motor 5. Carriers 14 and scooping devices 17 on the inner surface of the drum shell ensure improved mixing of the aqueous liquid 7 with laundry items (not shown here). The washing machine 1 also comprises a water supply system comprising a water connection fitting 20 for the domestic water supply, an electrically controllable valve 21, and a supply line 13 to the tub 2, which may optionally also be routed via a detergent dispenser tray 12, from which the incoming water can transport detergent portions into the tub 2 during a washing process. Furthermore, a heating device 16 is located in the tub 2.The valve 21 as well as the heating device 16 can be controlled by a control device 8 depending on a program flow plan, which can be linked to a time program and / or to the achievement of certain measured values ​​of parameters such as water level, water temperature, drum speed, etc. within the washing machine 1. 9 denotes a motor-drum control unit.

[0057] In this embodiment, the washing machine 1 has an acoustic and / or optical input and display unit 11 with which, for example and in particular, the execution of a washing program can be displayed.

[0058] 18 denotes a pump (drain pump) connected to the control device 8 for pumping the aqueous liquid 7 out of the suds container 2 and, if necessary, for temporarily assisting the method according to the invention. For this purpose, the drain pump 18 is arranged in the drain channel 23. A primary filter device 22 with a rotatable filter element 24 for separating a moist mass 25 containing microplastic particles from an aqueous liquid 7 from the suds container 2 is arranged in the drain channel 23. The primary filter device 22 is connected via a conveying line 26 to the secondary filter device 4 next to the dispenser tray 12. The secondary filter device 4 serves to receive the moist mass 25 containing microplastic particles separated by the filter element 24, as well as small parts not shown in detail here. The second filter device 4 contains a water-permeable filter bag 6 for receiving the moist mass 25 containing microplastic particles.

[0059] Fig. 2 shows in an open, from the laundry treatment device of Fig. 1 in the state pulled out by a user, a one-piece arrangement comprising a dispenser tray 12 and a second filter device 4. The internal structure of the dispenser tray 12 and a lower part of the second filter device 4 is clearly shown here, wherein no filter bag is shown on the filter bag engaging part 10.

[0060] Fig. 3 shows a secondary filter device 4 as shown in Fig. 2 is arranged behind the induction bowl. In the secondary filter device 4 of the Fig. 3, a filter bag 6 is attached to a filter bag snap-in part 10. This can be opened by a user to dispose of filtered particles and small parts. However, the filter bag 6 used here is permeable to microplastic particles due to the relatively large mesh size. List of reference symbols 1 water-conducting household appliance; washing machine 2 lye containers 3 drums 4 Secondary filter device 5 Drive motor for the drum 6 filter bags 7 aqueous liquid 8 Control device 9 Motor-drum control unit 10 Filter bag snap-in part 11 optical and / or acoustic input and display unit 12 (Detergent) dispenser tray 13 Supply line to the suds container 14 drivers 15 Water-permeable bottom wall of the second filter device 16 Heating device 17 Scooping device 18 Pump 19 axis of rotation 20 Water supply, domestic water network, water supply 21 (electrically controlled) valve 22 Primary filter device 23 drainage channel 24 Filter element in the first filter device (for filtering out microplastic particles) 25 Filter pad; moist mass containing microplastic particles 26 Conveyor line for mass and small parts containing moist microplastic particles

Claims

[1] Method for operating a water-conducting household appliance (1), comprising a primary filter device (22) arranged in a drainage channel (23) of the household appliance (1) with a rotatable filter element (24) for separating a mass (25) containing microplastic particles from an aqueous liquid (7), a discharge pump (18) arranged upstream of the primary filter device (22) in the flow direction, and a secondary filter device (4) which is fluidically connectable to the primary filter device (22) via a conveying line (26), wherein in a rinsing phase of the primary filter device (22) the rotatable filter element (24) is rotated such that a flow in the direction of the secondary filter device (4) is generated in the aqueous liquid (7). [2] Method according to claim 1, characterized byin that the filter element (24) is a cylindrical filter element and the primary filter device (22) is designed to rotate the cylindrical filter element (24) in such a way that the mass (25) containing microplastic particles deposited on the filter element (24) is thrown off and, together with any small parts accumulated in front of the filter element (24), is conveyed through the conveying line (26) into the secondary filter device (4) due to a suitably generated flow. [3] Method according to claim 1 or 2, characterized by that a pump wheel is arranged on the rotatable filter element (24). [4] Method according to one of claims 1 to 3, characterized by that the secondary filter device (4) is arranged next to or in a dispensing bowl (12). [5] Method according to claim 4, characterized by that the induction bowl (12) is connected to the secondary filter device (4). [6] Method according to claim 4 or 5, characterized by that the second filter device (4) is arranged behind the induction bowl (12). [7] Method according to one of claims 1 to 6, characterized by that a drive motor for the rotatable filter element is briefly switched on and off during the process. [8] Method according to one of claims 1 to 7, characterized by that the discharge pump (18) is also operated at least temporarily. [9] Method according to one of claims 1 to 8, characterized by that the secondary filter device (4) has a secondary filter with a low hydraulic resistance which is permeable to microplastics. [10] Water-conducting household appliance (1) comprising a control device (8), a primary filter device (22) arranged in a drainage channel (23) of the household appliance (1) with a rotatable filter element (24) for separating a mass (25) containing microplastic particles from an aqueous liquid (7), a discharge pump (18) arranged upstream of the primary filter device (22) in the flow direction, and a secondary filter device (4) which is fluidically connectable to the primary filter device (22) via a conveying line (26), characterized by that a method according to one of claims 1 to 9 can be carried out in the water-conducting household appliance.

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