EP3708705B1 - Method for operating a liquid-conducting domestic appliance and liquid-conducting domestic appliance - Google Patents

Description

The present invention relates to a method for operating a liquid-carrying household appliance and a liquid-carrying household appliance.

Liquid-carrying household appliances are well known from the prior art, for example in the form of washing or drying machines, but also dishwashers. Essential components of such liquid-carrying household appliances are a liquid reservoir in which, for example, in the form of a tub, a used suds or dirty water is collected after a washing process, as well as a pump element and a discharge line. The liquid collected in the liquid reservoir is conveyed out of the liquid-carrying household appliance via the discharge line by means of the pump element. In particular, the pump element pumps the liquid as a rule to a connection area of the liquid-carrying household appliance, which is arranged in the housing above the pump element and the liquid reservoir, in particular above a filling level of the liquid reservoir, in order, for example, to prevent the liquid from leaking out of the device in the event of a fault. Via external, i. H. outside of the liquid-carrying household appliance, the liquid-carrying household appliance can then be connected to a domestic drainage pipe system via an installation area, so that the liquid pumped out of the liquid reservoir by means of the pump element can be discharged from the liquid-carrying household appliance via the external connection line into the drainage pipe system.

The use of pump elements that are equipped with variable-speed motors has proven to be advantageous in order to set an optimum operating point for operating the pump element when pumping the liquid out of the liquid reservoir. When setting the optimum operating point, in particular for speed adjustment, a liquid column is decisively taken into account, which builds up in the discharge line on the outlet side above, i.e. on the pressure side, of the pump element and acts on the pump element due to the force of gravity. In addition to the dimensioning of the discharge line and/or the position of the connection area, the position of the installation area and the dimensioning and design of the connection line can also have an influence on the size of the liquid column reacting on the pump element. For example, an installation area of the drain pipe system can be arranged above the connection area, so that the liquid column, which reacts on the pump element or against which the pump element has to work additionally during operation, is made up of a device-internal part and a device-external part. The liquid column acting on the pump element then does not correspond to the one that occurs, for example, when the installation area is below the connection area or even below a reference height that is defined by the position of the pump element within the liquid-carrying household appliance. Correspondingly, an optimum operating point for the pump element, which is to be set depending on the liquid column reacting on the pump element, largely depends on the installation conditions under which the fluid-carrying household appliance is installed, in particular its position relative to the installation area.

Irrespective of the fact that the fact that achieving the optimal operating point depends on the installation conditions fundamentally restricts the use of the liquid-carrying household appliance, some user-side framework conditions (e.g. structural conditions) do not allow the liquid-carrying household appliance to be installed within the firmly defined installation conditions . As a result, using the liquid-carrying household appliance outside of the optimal operating point can lead to sporadic spin failures under maximum load conditions (strong imbalances and foamed washing suds rotating in the suds container or in the liquid reservoir, which then massively increase the drive torque). In addition, in the event of a device error, it is not possible to ensure safe operation as required by the standard.

It has therefore turned out to be advantageous to determine the respective installation conditions and to automatically set an operating point of the pump element in accordance with the installation conditions actually present. For example, from the DE 10 2013 100 373 A1 a method is known in which the pumping height is adjusted by continuously increasing the pump speed of the pump element until a pump parameter changes discontinuously. From this, the real pumping height can be determined, which is influenced, for example, not only by a device-internal fluid column, but also by a device-external fluid column or by a reduction in the device-internal fluid column compared to a maximum possible device-internal fluid column.

From the prior art is also from the DE 10 2015 209 705 a liquid-carrying household appliance with a speed-controlled pump device is known, in which the pump device returns energy to the liquid-carrying household appliance in turbine operation and can recognize a special operating state of the fluid-carrying household appliance.

In the DE 10 2010 028 614 discloses a pump device for a liquid-carrying household appliance, in which an electrical parameter of the pump device is detected by means of a detection unit and the pump device is activated by means of a control device depending on the detected electrical parameter.

Proceeding from this, the object of the present invention is to provide a method which is improved over the methods known from the prior art.

This object is achieved by a method according to claim 1 and a liquid-carrying household appliance according to claim 10. Further advantages and features of the invention result from the dependent claims and the description and the attached figures.

According to a first aspect of the present invention, a method is provided for operating a liquid-carrying household appliance with a pump element, a liquid reservoir and a discharge line, wherein in a first operating state a liquid is conveyed out of the liquid-carrying household appliance via the discharge line from the liquid reservoir and into In a second operating state, a return flow of the liquid from the discharge line into the pump element is detected by the pump element and the detected return is used to draw conclusions about an installation condition for the liquid-carrying household appliance or the installation condition for the liquid-carrying household appliance is determined.

Compared to the prior art, it is possible in an advantageous manner to determine the return in a second operating state in order to draw conclusions about the erection condition on the basis of the detected return. The return of the liquid from the discharge line into the pump element, i.e. its volume, for example, is advantageously used to determine the installation condition, so that the pump speed does not have to be increased continuously until a corresponding pump parameter becomes discontinuous, as is the case, for example, in DE 10 2013 100 373 A1 is made. For this purpose, the second operating state is assumed immediately after the first operating state, i.e. the discharge line and a connecting line are first flooded with the liquid and then the pump element is put into the second operating state, in which it allows the return flow of the in the first operating state in the discharge line and the Connection line pumped liquid recorded. It is preferably targeted, for example by pressing a button or by a corresponding program sequence when the liquid-carrying household appliance is switched on, the pump element is switched on for a first time interval to assume the first operating state and then switched off for a second time interval in order to allow the liquid pumped during the first time interval or part of it to flow back in a targeted manner in the second time interval. Based on a voltage, current intensity and/or frequency recorded by the pump element in turbine operation, the size of the volume of the return can then be deduced, which in turn can be used to deduce the installation condition, since it provides information on the liquid column formed on the pump outlet side.

In particular, in the first operating state, the liquid is conveyed along a preferred flow direction, with which it is conveyed out of the fluid-carrying domestic appliance, while the return flow is opposite to the direction of flow. It is preferably provided that in the first operating state a motor of the pump device is switched on and in the second operating state the motor of the pump device is switched off or not actively supplied with current, i. H. the pumping device is in turbine operation in the second operating state. In other words: the pump device or the pump element is switched to turbine operation in the second operating state by water flowing back. This advantageously allows conclusions to be drawn about the amount of liquid during the return flow based on a voltage recorded over time in the second operating state, which in turn is a measure of the liquid column acting on the pump element and which allows conclusions to be drawn about the erection condition.

The installation condition is to be understood in particular as a relative orientation of an installation area with respect to the pump element or the liquid level in the liquid reservoir. The installation area forms an interface via which the liquid-carrying household appliance is connected to a domestic drainage pipe system by means of an external connection line. For example, the installation area is a connection embedded in a wall.

The concept of the installation condition also includes a course of the connection line, which can also have turns, for example. In particular, the method according to the claims can be used to check whether the currently recorded return is consistent with the installation condition that is required for an optimal operating process, in particular with regard to a set operating point. It is preferably provided that a voltage generated by the liquid flowing back through the pump element is recorded in the second operating state by means of a measuring device in terms of duration and magnitude. This measuring device is preferably connected to the pump element in such a way that the measuring device can detect a voltage in the second operating state in which the pump element is operated as a turbine, so that the detected voltage can be used to draw conclusions about the setup condition.

The liquid-carrying household appliance is preferably a washing machine, a washer-dryer or a dishwasher, i.e. a liquid-carrying household appliance for treating objects, in particular items of laundry and/or household objects, e.g. crockery. The liquid-carrying household appliance is very particularly preferably a washing machine. A washing machine generally has a tub as a liquid reservoir.

The pump element is preferably a centrifugal pump. In general, a centrifugal pump is also referred to as a centrifugal pump, since the pumping principle is based on the use of centrifugal force to pump a liquid. A central component of a centrifugal pump is usually the impeller, which can be designed radially, semi-axially or axially. The type of construction of the centrifugal pump is not restricted, but a centrifugal pump with an axially or preferably radially formed impeller is preferably used.

In general, a centrifugal pump can also be used as a turbine without necessarily having to change the shape of the housing or the impeller geometry requirement. However, it is conceivable that, particularly when the turbine is operated in the reverse direction of flow, reverse rotation speeds that are too high occur. To prevent this, a backstop can be attached to the pump shaft, for example if the reverse rotation speed is too high. As used herein, "reverse speed" means the number of revolutions per minute of the impeller running in reverse, that is, when the impeller is subjected to reverse flow direction. In contrast, "RPM" means the number of revolutions per minute that the impeller makes when the flow is in the direction of flow.

The centrifugal pump is preferably driven by a speed-controlled drive motor. The design of the speed-controlled drive motor is not restricted. For example, it can be a three-phase motor, which can be an asynchronous motor or a synchronous motor. In any case, the speed of the drive motor can be varied. For this purpose, the drive motor can have a power converter, for example.

The pump element is preferably equipped with a synchronous motor. In general, the synchronous motor consists of a fixed stator and a rotatable rotor, which can be designed as an external or internal rotor. The stator usually consists of a housing, a stator core and a stator winding, the stator winding usually being a three-phase winding for generating the rotating magnetic field. The rotor generally has a solid or laminated pole core and carries an excitation winding that is supplied with direct current via slip rings. It acts as an electromagnet and its number of poles is generally as large as the number of poles of the stator winding.

In a further conceivable embodiment, a synchronous motor is used which has a permanent magnet rotor as the rotor. As a result, the synchronous motor has a fixed, permanent magnetic field, which usually ensures higher efficiency and a simpler motor design. This synchronous motor is referred to herein as a permanent magnet synchronous motor. In a particularly preferred embodiment, the permanently excited synchronous motor has at least one 3-phase winding, but the winding is preferably designed with multiple strands. According to the invention, such a synchronous motor is referred to herein as a permanently excited, multi-phase synchronous motor.

For example, the liquid-carrying household appliance, in particular the permanently excited, multi-phase synchronous motor, has a power converter. As a result, the rotational speed of the synchronous motor can be varied by means of activation by the control device. The type of power converter used is not restricted, but a power converter with IGBT or MOSFET components is preferably used.

The power of the speed-controlled drive motor used in the pumping element is usually detected by means of a power detector. The power recorder can record, for example, an electrical current and/or an induced electrical voltage and/or an electrical power as electrical parameters and transmit it to an evaluation device and/or control device.

In general, the speed-controlled drive motor and the pump element are drivingly connected to one another, for example via a drive shaft. In turbine operation of the pump element, however, the speed-controlled drive motor is generally switched off. In turbine operation, the drive does not take place via the speed-controlled drive motor, but via the movement of the impeller of the pump, so that the drive motor works like a generator in turbine operation. In this case, the pump element is used in the second operating state in turbine operation.

Energy is preferably generated during turbine operation and fed back into the household appliance.

According to a preferred embodiment, it is provided that the second operating state is assumed during an installation and/or during a maintenance measure and/or during commissioning and/or when the liquid-carrying household appliance is switched on and/or switched off and/or in a monitoring state . This means that at fixed times the pump element is used to determine the return flow of the liquid from the discharge line into the pump element and, for example, to draw conclusions about the currently present installation conditions on the basis of the determined return flow. It is advantageous that, in addition to the measurement during installation or maintenance work, also in regular operation, i.e. when starting up or switching off the liquid-carrying household appliance, the installation conditions are determined or confirmed again, so that the liquid-carrying household appliance can also recognize, for example, if it is converted and the installation conditions have therefore changed accordingly. It is also possible to monitor and record the recorded returns over longer periods of time. This also allows conclusions to be drawn about changes in the overall system, for example as a result of deposits in the lines.

In particular, the targeted initiation of the second operating state during maintenance work proves to be advantageous, since another pump element does not have to be installed in a costly manner in order to infer a possibly unfavorable installation condition. The method is preferably carried out before and/or during each wash cycle or each time the liquid-carrying household appliance is put into operation. This ensures that a change in the installation area is recognized as quickly as possible.

It is preferably provided that in a monitoring state, a return or a forward flow is detected by means of the pump element and a special operating state is inferred based on the return flow and/or forward flow detected in the monitoring state. In this case, under forward flow of the To understand liquid along a direction that the liquid follows when it is pumped out with the pump element from the liquid-carrying household appliance (pump preferred direction of rotation). In the monitoring state, the pump element is switched off or not energized or actively driven, so that the forward flow or return flow is the consequence of a vacuum or of liquid running back into the liquid-carrying household appliance, ie an unexpected turbine operation or second operating state is present , in which the pump element is operated in the second quadrant of the pump-throttle-curve characteristic map, so to speak, with negative delivery flow and positive delivery pressures. A monitoring state is to be understood above all as a state in which the liquid-carrying household appliance is in a stand-by mode and, for example due to a special operating state caused by a fault, a return or forward movement occurs in the liquid-carrying household appliance, which would not normally be expected and accordingly can indicate a malfunction in the entire hydraulic system. For example, it is conceivable that a blockage in the domestic drainage pipe system leads to a backwater of the liquid, which even forces liquid back through the connection line into the drainage line, so that the liquid does not only flow back into the pump element. By detecting a voltage in this monitoring state, the pump element can thus also be used explicitly to determine any special operating states in order to take appropriate countermeasures.

Such a special operating state can be, for example, emptying or raising all the liquid from the liquid-carrying household appliance. Such a special operating state is usually caused by a negative pressure in the domestic water line connected to the household appliance. Such a condition is in particular intensified if, under special installation conditions or situations, the discharge line of the household appliance is installed far into a floor drainage, ie the suspension height or an installation height is even negative. After the one-time Overcoming the internal height of the device, a flow of liquid occurs here, regardless of whether the pump element is switched on or not. In any case, the emptying of the liquid-carrying household appliance causes liquid to flow through the discharge line out of the household appliance. The impeller of the pump element is flown against in the direction of flow of the discharge line - i.e. in the pump's preferred direction, which means that the pump element operates in the opposite direction when the drive motor is switched off and energy is also fed back as a result if the pump element is in the fourth quadrant with positive delivery flow and negative delivery pressures of the pump throttle curve map is operated.

In a preferred embodiment of the liquid-carrying household appliance, the delivery capacity of the pump element can be set up by the control device via the speed-controlled drive motor in such a way that only a certain amount of liquid is pumped out of the liquid-carrying household appliance, which is necessary to overcome the internal device height and thus initiate automatic emptying . In a particularly preferred embodiment of the liquid-carrying household appliance, the speed-controlled drive motor is therefore a permanently excited, multi-phase synchronous motor with, for example, a MOSFET component and a power converter, which is connected to the control device. The amount of liquid that is required to overcome an internal device height can usually be determined as a function of the installation conditions for each household device and stored in the control device. After initiating emptying, the control device of the liquid-carrying household appliance is set up to stop the speed-controlled drive motor of the pump element, so that the pump element changes from pump operation to turbine operation. The energy fed back by the drive motor during turbine operation can then preferably be stored in the household appliance and/or used to operate it.

Furthermore, the energy fed back during turbine operation is generally detected by the power recorder or the measuring device and transmitted to the control device. The control device of the household appliance is set up in such a way that it recognizes the special operating state of emptying based on the amount of energy E _empty detected by the power detector.

A special operating state of a liquid-carrying household appliance is also conceivable, in which the discharge line is flooded at the back through the connection line, for example if it is blocked and liquid is pressed out of the connection line into the household appliance. In this case, the liquid flows against the impeller of the pump element in the opposite direction to the flow direction of the discharge line or the preferred direction of rotation of the pump, since the household appliance is filled from the waste water side. Turbine operation begins in the opposite direction to the preferred pumping direction of the pump element. The speed at which the impeller of the pump element runs in turbine operation against the preferred pump direction is generally referred to as the reverse speed. The reverse speed can be lower than the forward speed in the preferred pump direction but occasionally higher. In addition, the flow speed is generally lower when the rear of a liquid-carrying household appliance fills up, so that this also usually results in only low return speeds of the pump elements. Therefore, the amount of regenerated energy E is generally lower when the turbine is running backwards. In any case, in a special operating state, which is caused by rear filling, a smaller amount of energy E _full is fed back than is the case in the special operating state emptying with forward running turbine operation, since in emptying caused by negative pressure significantly higher liquid flows are achieved and thus significantly higher speeds of the Pump element in forward running turbine mode.

It is also conceivable that a special operating state occurs in a liquid-carrying household appliance due to a defect, for example due to a defective appliance solenoid valve on a fresh water supply line. In this case, the household appliance will generally first fill up with liquid on the inside and eventually run out. If liquid from the inside runs out of the device through the discharge line, the impeller of the pump element is flown against in the direction of flow, provided no further opening is provided in the tub, for example for ventilation purposes. Turbine operation thus begins when the drive motor is switched off. This turbine operation is also forward-running and higher speeds are generally achieved than in reverse-running turbine operation. In addition, when the liquid flows out of the liquid-carrying household appliance into the domestic water pipe, the onset of negative pressure can increase the flow rate and thus contribute to an increase in the pump speed in turbine operation. In any case, a larger quantity of energy E _Aus is also fed back for a special operating case "internal run-out" than is the case for a special operating case "filling up".

A special operating state of a liquid-carrying household appliance is, in particular, emptying by the pumps on the pressure-side connection line in the event of negative pressure, rear filling caused by the connection line or domestic sewage line in the event of clogging and/or internal leakage caused by an internal defect.

In general, the pump element works in turbine mode when there is a special operating state in or on a liquid-carrying household appliance, and energy is fed back into the household appliance from the switched-off, speed-controlled drive motor, which works as a generator in turbine mode of the pump element. The quantities of energy E fed back are dependent on which special operating state is present and in which form. It is generally the case here that a quantity of energy E that is fed back is greatest when there is a special operating state of sucking empty and is lowest when there is a special operating state of filling up on the back is present, for a special operating case of internal slowing down, the amount of energy fed back is in the middle range, ie E _empty > E _off > E _full .

Such special operating states are generally recognized by the control device based on the amount of energy E fed back detected by the power detector when the pump element is operating in the turbine Amount of energy fed back E _empty the special operating state emptying.

As a rule, at least one measure is stored in the control device for an existing special operating state, which is carried out by the control device when the existing special operating state is detected.

In general, household appliances that carry liquids have display elements via which information and/or options for action can be output to a user and can be carried out by the user. In principle, such display elements are not restricted in terms of type, shape and content reproduction, but a display is preferably used, particularly preferably a color display and very particularly preferably a touch display, on which content, such as information and/or options for action, is written and / or image, preferably highlighted in color, can be displayed.

A measure to be taken when a special operating state is present usually includes displaying information about the special operating state recognized by the control device on the display element of the liquid-carrying household appliance, e.g. B. the indication that the liquid-carrying household appliance is being sucked empty and/or the indication that there is an internal defect and the household appliance is running out, and/or the indication that the household appliance is filling up on the back. In this way, a user receives direct informational help and can, if necessary, take necessary actions based on this early, such as shutting off the domestic fresh water supply in the event of internal leakage before, for example, the room in which the household appliance is installed is flooded.

In general, however, it is also conceivable that a further measure to be carried out in the event of a special operating state or unfavorable installation conditions includes issuing an option for action to a user. In this way, measures can be proposed to the user, which he can initiate in order to counteract possible damage at an early stage in the event of a special operating state or an unsuitable installation condition. In a preferred embodiment of the liquid-carrying household appliance, options for action are assigned to a present special operating state in the control device. For example, one option for action in the presence of the special operating state of emptying is "replenish the treatment agent". An option for action in the presence of the special operating state of internal leakage is e.g. "Service required". An option for action in the presence of the special operating status rear filling is, for example, "run program" and/or "run self-cleaning".

Furthermore, a measure to be taken in the presence of a special operating state includes switching on the pump element. Switching on the pump element is usually necessary when unwanted liquid has to be removed from the liquid-carrying household appliance, for example if the household appliance fills up on the back, the pump element can counteract this if the pressures present are not too high. In a preferred embodiment of the liquid-carrying household appliance according to the invention, the speed-controlled pump element is directly activated and switched on and/or its speed increased by the control device upon detection of a special operating state of internal leakage and/or rear filling.

Provision is preferably made for the recorded returns to be compared with one another over a plurality of second operating states by means of an evaluation device and/or a storage device. This not only registers a change in the installation conditions, but also long-term changes in the hydraulic system. For example, blockages and/or line constrictions in the pump pressure-side connection line and/or the discharge line can be detected, which occur over time and correspondingly also reduce the flow rate of the return flow or reduce the volume of the return flow. Using a corresponding evaluation device, it is therefore possible to determine via a number of second operating states whether a continuous steady decrease in the return flow can be determined and whether an appropriate countermeasure should be initiated.

Provision is preferably made for a warning signal to be output and/or a pump parameter for the first operating state to be adjusted as a function of a magnitude and/or a point in time of the detected return. The rotational speed of the pump element is preferably adjusted as a function of the fixed installation condition. It is also conceivable that a warning signal is sent to the user of the liquid-carrying household appliance to inform him that the current connection conditions do not conform to the design of the pump element and therefore do not conform to the specified appliance installation conditions. The speed at the pump element is particularly preferably automatically adapted to the recorded installation condition or to the correspondingly recorded return.

Provision is preferably made for the pumping parameter of the pumping element to be adjusted after a specified number of recorded returns. As a result, the pump parameters can be adjusted regularly for operationally optimized use of the pump element in an advantageous manner, so that long-term changes, such as deposits in the connecting line and/or Discharge line, do not prevent the liquid-carrying household appliance from an operationally optimized use of the pump element. The specified number is preferably greater than 30. It is also conceivable that the pumping parameter is regularly adjusted once a month or once a year.

Provision is preferably made for the second operating state to be assumed immediately after a first operating state. As a result, the return flow of the liquid that was conveyed into the discharge line and the connection line in advance by means of the first operating state is detected in an advantageous manner. Provision is also made for the second operating state to take place according to a fixed schedule and/or to be able to be actively initiated, for example via a corresponding input device on the liquid-carrying household appliance.

It is preferably provided that an installation height of a connection line is additionally determined in the first operating state. By combining the determination of the installation height or the connection condition in the first operating state and in the second operating state, it is advantageously possible to carry out the same measurement redundantly in two different operating states of the liquid-carrying household appliance or the pump element. Regarding the determination of the pumping height or the connection condition, without determining this by means of the return, ie in the first operating state, the disclosure of the DE 10 2013 100 373 A1 referenced.

It is particularly preferably provided that when the liquid-carrying household appliance is installed, a dependency of the return on a height of an end of the connecting line on the installation area side is determined in the manner of a characteristic diagram. As a result, the detected voltage value or the value for the fed-back energy can be assigned precisely to a pumping-off level or input level, which in particular also affects the structural details of the connection line or discharge line into account, such as pressure losses due to hose laying and hose dimensioning, the existence of a water mountain ventilation or suds container ventilation or other pressure-side influencing variables on the liquid column.

A further object of the present invention is a control device for operating a liquid-carrying household appliance with a method according to the invention. All the features and advantages described for the method can be transferred to the control device and vice versa.

Another object of the present invention is a liquid-carrying household appliance with a liquid reservoir, a discharge line and a pump element, the pump element between a first operating state in which a liquid is discharged from the liquid reservoir via the discharge line from the liquid-carrying household appliance by means of the pump element and a second operating state in which a return of the liquid from the discharge line into the pump element is determined by means of the pump element, can be transferred. All the features and advantages described for the method can be transferred to the liquid-carrying household appliance and vice versa.

Further advantages and features emerge from the following description of preferred embodiments of the subject with reference to the attached figure. Individual features of the individual embodiment can be combined with one another within the scope of the invention.

Fig. 1:

ein flüssigkeitsführendes Haushaltsgerät gemäß einer bevorzugten Ausführungsform der vorliegenden Erfindung,

Fig. 2:

ein Pumpenelement mit einem an der Druckkammer tangential angeformten Druckstutzen für ein flüssigkeitsführendes Haushaltsgerät aus Figur 1 und

Fig. 3

ein Flussdiagram für Verfahren zur Betrieb eines flüssigkeitsführenden Haushaltsgeräts aus den Figuren 1 und 2.

It shows:

Figure 1:

a liquid-carrying household appliance according to a preferred embodiment of the present invention,

Figure 2:

discloses a pump element with a pressure port tangentially formed on the pressure chamber for a liquid-carrying household appliance figure 1 and

3

a flowchart for methods for operating a liquid-carrying household appliance from figures 1 and 2 .

In figure 1 a liquid-carrying household appliance 1 is shown according to a preferred embodiment of the present invention. The essential components of such a liquid-carrying household appliance 1 are a liquid reservoir 6, a pump element 2 and a discharge line 4. For example, the liquid-carrying household appliance 1 is a washing machine or a dishwasher, in which the pump element 2 is used to drain a used liquid that is in the liquid reservoir 6 is collected, for example a lye or dirty water, is conveyed out via the discharge line 4 from the liquid-carrying household appliance 1. The discharge line 4 leads the liquid to a connection area 10 which is arranged in particular above the pump element 2 and above the liquid reservoir 6 . The pump element 2 is preferably arranged in a lower part of a housing 3 of the liquid-carrying household appliance 1 , while a connection area 10 can be found in the upper area of the housing 3 of the liquid-carrying household appliance 1 . The liquid-carrying household appliance 1 can then be connected to a drain pipe system (not shown) via a connecting line 8 . The connecting line 8 running outside of the liquid-carrying household appliance 1 ends in a domestic installation area 12, for example at a corresponding interface in a wall.

For the optimal design of the pump element 2, in particular for its operation-optimized speed setting, the size of a liquid column acting back on the pump element 2, which is located within the discharge line 4, if necessary at least partially, is decisive during operation. Depending on a set-up condition, i.e. a relative orientation of the installation area 12 to the connection area 10, the liquid columns reacting on the pump element 2 can be of different sizes, so that different pressures and different sized return flow volumes react on the pump element 2. in the in figure 1 The example shown shows the installation area for a first installation height H1, for a second installation height H2 and a third installation height H3. In the case of the first installation height H1, the installation area 12 is higher than the connection area 10 or is greater than a connection height AH assigned to the connection area 10 in relation to a reference height RH, which is related to a height of the pump element 2 in the vertical direction VR. In this case, the liquid column above the pump element 2 is made up of a device-internal part in the discharge line 4 and a device-external part within the connection line 8 . In the case of the second installation height H2, the second installation height H2, viewed in the vertical direction VR, lies between the reference height RH and the connection area 10. In this case, the liquid column above the pump element 2 is essentially determined by the device-internal liquid column. Finally, it is also possible that the installation area 12 is arranged at the third installation height H3, which is arranged below the reference height RH. In this case, the device-internal liquid column above the pump element 2 can be reduced compared to a completely filled discharge line 4. In view of the dependency of the pressure acting on the pump element 2, caused by the liquid column in the discharge line and/or connection line, speed-optimized operation of the pump element is required helpful to know whether the connection conditions are optimal and/or which connection conditions exist, either to inform the user that the connection conditions are contrary to a current optimal operation or to adjust the speed of the pump element 2 accordingly, preferably automatically.

For this purpose, it is provided that the pump element 2 moves from a first operating state B1, in which it conveys the liquid out of the liquid-carrying household appliance 1 along a conveying direction or flow direction, to a second operating state B2, in which an independent return RF - i.e. without an activated pump element from the discharge line 4 is detected in the pump element 2, can be transferred. The return flow RF recorded on the pump element 2 advantageously makes it possible to draw conclusions about the installation conditions, in particular about an installation height H1, H2, H3 of the external connection line 8 in relation to the connection area 10. A measuring device 30 is provided for this purpose, which, for example, a voltage of the pump element 2 is detected when this acts as a turbine in the second operating state B2 and, driven by the return flow RF, generates a voltage. The information about the return RF recorded by means of the measuring device 30, in particular about the existence of the return RF and/or a quantity of a return RF, is then forwarded to an evaluation device 31 which, for example, determines the quantity of the return RF based on the detected temporally occurring voltage . The evaluation device 31 can then use a control device 35, for example, to adapt the speed of the pump element 2 for the first operating state B1, so that the pump element 2 can be operated at an optimized speed when pumping the liquid out of the liquid reservoir 6 from the liquid-carrying household appliance 1. In addition, it is conceivable that the information about the return RF, in particular the time and/or quantity of the return RF, is stored in a storage device 32. By comparing it with previously recorded returns RF or specific volumes of the returns RF, it is then in advantageously possible to determine whether the installation conditions have changed since the liquid-carrying household appliance 1 was last operated, for example due to a new connection. Alternatively, it is also conceivable for the stored information to be used to determine whether changes have taken place over a longer period of time, for example with regard to the size of the return volume recorded. This could indicate, for example, that a line inner diameter of the discharge line 4 and/or connection line 8 is reduced due to possible calcification and/or deposits and the return flow volume has decreased accordingly or due to an increased flow resistance, which occurs due to the smaller flow cross sections caused by the deposits, the flow speed of the return flow is also reduced.

Provision is also made for an output device 33 to be provided which, for example, informs the user about the existence of a non-optimal connection condition or a non-optimally set speed of the pump element 2 . For example, such an output device 33 is a display that is attached to the outside of the housing 3 . However, it is also conceivable that the output device 33 forwards a corresponding warning or information to a mobile end device, such as a tablet or a smartphone, by wireless communication.

In figure 2 1 is an example of a pump element 2 for a device figure 1 shown in different views. In particular shows figure 2 the second operating state, in which a return RF runs through a first pump pipe or the pump pressure connection 21 into the pump element 2, where, due to the tangential arrangement of the pressure connection 21, drives an impeller 23 to rotate about an axis of rotation R and then the pump element 2 via the suction connection 22 leaves. For the best possible degree of efficiency, it is particularly preferred that the first pump pipe 21 (pump pressure port) is arranged tangentially on a pressure chamber. For example, the pump element 2 is a centrifugal pump, in particular a radial centrifugal pump. In particular, the figure 2 It is not a pump in which the pressure chamber has a radial pressure connection or first pump pipe, so that pumping can always take place with the same flow rate, regardless of the direction of rotation of the impeller. For turbine operation, however, this means that the impeller does not necessarily have to rotate. Is the pressure port however, arranged tangentially, as shown in figure 2 is shown, a rotation of the impeller is inevitably caused.

In figure 3 a flowchart for a method according to a preferred embodiment of the present invention is presented. In particular, the method provides that a first operating state B1 is set by switching on the pump element 2 and a second operating state B2 is initiated by switching off the pump element 2 . By measuring 101 a voltage over time in the second operating state B2 on the pump element 2, the return flow RF is then determined 102 to determine the set-up condition and, if necessary, a warning signal is output 103 .

Reference list:

1

liquid-carrying household appliance

2

pump element

3

Housing

4

discharge line

6

fluid reservoir

8th

connecting cable

10

connection area

12

installation area

21

first pump pipe or pump pressure nozzle

22

second pump tube or pump suction port

23

Wheel

30

measuring device

31

evaluation device

32

storage facility

33

output device

35

control device

101

Measure

102

Determine

103

output

H1

first installation height

H2

second installation height

H3

third installation height

RH

reference height

AH

connection height

R

axis of rotation

RF

return

B1

first operating state

B2

second operating state

Claims (10)

1. Method for operating a liquid-conducting household appliance (1) having a pump element (2), a liquid reservoir (6) and an output line (4) by means of a control facility (35), wherein in a first operating state (B1) a liquid is carried out of the liquid reservoir (6) via the output line (4) from the liquid-conducting household appliance (1) by means of the pump element (2), and characterised in that in a second operating state (B2), a return flow (RF) of the liquid out of the output line (4) into the pump element (2) is detected by means of the pump element (2), wherein an installation condition of the liquid-conducting household appliance (1) is determined on the basis of the return flow (RF) detected in the second operating state (B2), wherein the installation condition is a relative alignment of an installation region (12) with respect to the pump element and/or a liquid level in the liquid reservoir (6) and/or a course of a connection line (8).
2. Method according to claim 1, wherein the second operating state (B2) is assumed

   - with an installation and/or

   - with a maintenance measure and/or

   - with a commissioning and/or

   - with a switching-off and/or

   - before or during a washing program

   of the liquid-conducting household appliance (1).
3. Method according to one of the preceding claims, wherein in addition the second operating state (B2) is assumed in a monitoring state, wherein a return flow (RF) or an inlet flow is detected by means of the pump element (2) and a special operating state is concluded on the basis of the return flow (RF) and/or inlet flow detected in the monitoring state, wherein the special operating state is a draining by pumping the pressure-side connection line (8) at low pressure, a rear-side filling-up produced by the connection line (7) or domestic waste water disposal line in the event of a blockage and/or an internal leak produced by an internal fault.
4. Method according to one of the preceding claims, wherein the detected return flows are compared with one another over a number of second operating states (B2) by means of an evaluation facility (31) and/or a storage facility (32).
5. Method according to one of the preceding claims, wherein a warning signal is output as a function of a size and/or a time instant of the detected return flow (RF) and/or a pump parameter of the pump element (2) is adjusted to the first operating state (B1).
6. Method according to one of the preceding claims, wherein after a defined number of detected return flows, the pump parameter of the pump element (2) is adjusted.
7. Method according to one of the preceding claims, wherein the second operating state (B2) is assumed immediately after a first operating state (B1).
8. Method according to one of the preceding claims, wherein with the installation of the liquid-conducting household appliance (1), a dependency of the return flow (RF) on a height of an installation region-side end of the connection line (8) is determined in the manner of a characteristic diagram.
9. Control facility (35) for operating a liquid-conducting household appliance (1) having a pump element (2), a liquid reservoir (6) and an output line (4) with a method according to one of the preceding claims.
10. Liquid-conducting household appliance (1) having a liquid reservoir (6), a output line (4), a control facility (35) and a pump element (2), characterised in that the pump element (2) can be transferred between a first operating state (B1), in which a liquid is carried out of the liquid reservoir (6) via the output line (4) from the liquid-conducting household appliance (1) by means of the pump element (2), and a second operating state (B2), in which a return flow (RF) of liquid out of the output line (4) into the pump element (2) is determined by means of the pump element (2), wherein the control facility is configured to be able to determine an installation condition of the liquid-conducting household appliance (1) on the basis of the return flow (RF) detected in the second operating state (B2), wherein the installation condition is a relative alignment of an installation region (12) compared with the pump element and/or a liquid level in the fluid reservoir (6) and/or a course of a connection line (8).

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