EP2746451A1 - Method for pumping a liquid from a water-conducting household device, in particular from a washing machine, and water-conducting domestic appliance - Google Patents

Abstract

The method involves conveying liquid from a lye tub (2) through a drain line (4) by an electrical lye pump (3) with an operation pump power of the lye pump. The pump power of the lye pump is subsequently gradually lowered during a switching off process so that a liquid column provided in the drain line does not exceed a maximum reflow speed of 0.5 m/s, preferably 0.4 m/s, 0.3 m/s, 0.25 m/s, 0.2 m/s during reflow along the drain line. A reduction rate of the pump power of the lye pump is limited during the switching off process. An independent claim is also included for a water-conducting domestic appliance.

Description

The invention relates to a method for pumping a liquid from a water-conducting household appliance, in particular from a washing machine, wherein the liquid is conveyed from a tub through a drain line by means of an electric lye pump at a Betriebsspumpleistung the drain pump and the power of the drain pump is then shut down in a shutdown ,

Such a method turns out, for example DE 10 2011 050 922 B3 known washing machine. The drain pump is used to pump out between washing cycles of a wash program, and at the end of a wash program, the existing in the tub spent washing liquid from the washing machine through a drain opening to the outside. After the liquid has been completely pumped out of the tub, the drain pump is turned off.

Usually, the drain opening, which is usually followed by a sewage hose outside the washing machine housing, is arranged above the drain pump, so that the liquid to be pumped off has to overcome a height difference in the drain line. As explained in the above-cited document, this height difference also serves as a return flow by liquid is kept in the liquid column to flow after switching off the drain pump back into the drain pump and to close there existing drain valve between the drain pump and tub. However, in the embodiments described below, a backflow preventer may also be provided in addition to the drain line in order to increase the volume of the returning liquid beyond the capacity of the drain line.

In the abrupt turn off the drain pump, however, it may happen that the liquid column still located in the drain line accelerates again in the direction of the drain pump due to gravity and abruptly flows back to the drain pump and possibly even back into the tub. In embodiments of the washing machine in which a vent line connects the tub to a dispenser, this rapid backflow can cause contaminated waste water to also flow into this vent line, which gradually clogs due to soiling. In addition, it often happens that due to the sudden acceleration The liquid column down a vacuum is created, which is finally noticeable by a loud and unpleasant Gurgelgeräusch.

The invention has for its object to make the pumping out of the liquid from the water-bearing household appliance reliable and hygienic.

The object is achieved according to the invention by a method having the features of claim 1 and by a water-conducting household appliance having the features of claim 10. Advantageous developments of the invention are listed in the subclaims.

The invention is based on the consideration, during the shutdown, the drain pump not abruptly or jerkily, but gradually shut down. This means that by activating the drain pump, the energy supply to the drain pump does not switch off immediately or shuts down to a minimum, but shuts down gradually or with intermediate steps. This does not mean an unavoidable delay of the switch-off process due to the control or pump motor electronics or the pump motor mechanism (for example due to the inertia of a rotor), which would inevitably occur in all lye pumps. Rather, it is about a scheduled, controlled or defined, gradual shutdown of the pumping capacity of the drain pump. This should preferably be controlled in such a way that a reduction rate of the shut down pumping power is limited. In other words, the pump power preferably proceeds substantially steadily from the operating pump power to zero.

Due to such a regulated shutdown of the drain pump pressure peaks in the drainage system and / or ventilation system of the water-bearing household appliance are reduced or even completely avoided. Preferably, the liquid column located in the discharge line does not exceed a maximum return flow rate of 0.5 meters per second (m / s) during its downward movement.

In a water-conducting household appliance implementing this method, a drain pump control device is accordingly provided which ensures the gradual shutdown of the drainage pump's power during the shutdown process. The water-conducting household appliance is in particular a washing machine or a dishwasher. In particular, this solution also works for a washing machine or a dishwasher, which have an additional circulation pump.

The water-bearing domestic appliance can be considered as a system of vessels or tubes communicating with each other, to which the drain line, the tub, if not separated by an outlet valve, the drain pump and possibly a vent line belong. Therefore, reducing the maximum velocity of the downflowing liquid column in the drain line also reduces the height up to which the liquid and contaminants carried therein are carried up the other ports of the pump, ie in the tub, if not separated by an outlet valve. or in the vent line.

It is therefore advantageous to provide the shutdown of the drain pump even more careful. In particular, it is advantageous if, during the shutdown process, the power of the drain pump is gradually shut down such that a liquid column located in the drain line has a maximum speed of 0.4 m / s, 0.3 m / s, 0.25 m / s or 0.2 m / s. This prevents that the liquid located in the drain line penetrates so far into the tub, into a vent line extending from the drain pump to the dispenser or even into the dispenser that contaminants can deposit there at heights that remain permanently below the water level. This could otherwise lead to a drying of the dirt on the inner surfaces of these areas in the household appliance.

The fact that the liquid column in the discharge line does not exceed a certain maximum speed or a maximum return flow rate means that the liquid in the discharge line moves downwards at a rate through the discharge line, ie in the direction of the drain pump, which in each case lies below this maximum speed , The speed of the liquid column can be measured in particular on a liquid surface or a liquid level at the upper end of the liquid column. Such a liquid surface forms in the return flow of the liquid in the direction of the drain pump when the liquid flow at the outlet of the drain line tears off. If there is a backflow preventer in the form of a liquid reservoir in or on the drain line, the liquid column expands around the liquid stored in the return flow safety device. The return safety device serves to ensure a residual filling quantity in the drain pump even when the liquid is completely pumped out, so that a drain valve present between the drain pump and the tub remains securely closed. The drain line itself can be dimensioned as a return flow protection.

Advantageously, the speed of the liquid column is the speed of the liquid at about half the height of the discharge line, that is, around the Speed at which the upper liquid level passes through a central area of the drain line. However, in certain embodiments, it may also be the velocity of the liquid as measured from the upper liquid level at the lower end of the drain line.

According to a preferred embodiment, it is provided that during shutdown the shutdown of the power of the drain pump is at least partially in stages and / or gradually. For example, it is possible that the capacity of the leach pump is first reduced to a certain first intermediate value in one or more stages before it is then gradually reduced from the first intermediate value to a second intermediate value or to zero. This may be useful if the first intermediate value corresponds to a liquor pump power which is sufficient to build up a sufficiently high pressure so that the liquid column in the drain line does not yet move back. In the subsequent gradual reduction of the caustic pump performance then the liquid column would slowly move back in the drain line. Alternatively, the gradual reduction of pumping power may occur after the gradual reduction, or the shutdown may be performed substantially entirely in single stages.

Conveniently, the gradual reduction of the caustic pump power can be performed ramped. In other words, the shutdown of the power of the drain pump can be at least partially ramped during shutdown. This means that the time course of the lye pump power is ramped. Here, the slope of the ramp determines the speed at which the drain pump is throttled, and thus indirectly the speed of the falling liquid column in the drain line. While it is possible for the sake of simplicity to reduce the drain pump power in a ramp with a constant slope, the ramp may be composed of several partial ramps with different slopes, for example, to make the shutdown process more efficient. The temporal course of the pumping power can also be composed of different ramp-shaped and / or non-ramp-shaped gradual and / or step-shaped partial progressions.

In an advantageous embodiment, the drain pump is a rotary pump, which is driven at operating speed at operating speed. In this case, it is advantageous if, during the switch-off process, the speed of the drain pump is reduced at least temporarily per second by less than 10%, 8%, 6% or 4% of the operating speed. Preferably, the speed of the lye pump is reduced, starting at the operating speed until the complete shutdown of the drain pump per second by less than said values, for example by the Speed is reduced ramp. The operating speed may be, for example, more than 3500 revolutions per minute (rpm), preferably between about 3500 to 4000 rev / min, more preferably between about 3200 to 3600 rev / min.

Specifically, it may be advantageous in a drain pump designed as a rotary pump that during shutdown the speed of the drain pump is at least temporarily reduced by less than 200 rev / min, 150 rev / min, 100 rev / min or 50 rev / min per second. Preferably, the speed of the lye pump is reduced starting at the operating speed until the complete shutdown of the drain pump by less than these values, for example by the speed is reduced in a ramp.

Preferably, a synchronous pump is used as the drain pump. In an expedient development, it is provided that the shutdown process, the gradual shutdown of the performance of the drain pump is done by a drive frequency of an electrical control or an electrical supply to the drain pump is varied. Varying the drive frequency can be done using a frequency converter.

In an advantageous embodiment, the liquid flows due to a difference in height by gravity from the tub in the drain pump. This means that the drain pump is not a suction pump. The liquid flowing into a pump chamber of the drain pump is forced through the pumping action of the drain pump through a pump outlet into the drain line. Advantageously, an outlet valve, for example, provided with a trained as a buoyant seal between the tub and the drain pump to prevent backflow from the drain pump into the tub.

Fig. 1

eine Querschnittsansicht einer Waschmaschine und

Fig. 2a und 2b

den zeitlichen Ablauf unterschiedlicher Abschaltvorgänge einer Laugenpumpe.

The invention will be explained below with reference to embodiments with reference to the figures. Hereby show:

Fig. 1

a cross-sectional view of a washing machine and

Fig. 2a and 2b

the timing of different shutdown a drain pump.

The Fig. 1 shows a water-conducting household appliance 1, namely in this case a washing machine, with a housing 11 and a tub 2, in which the washing drum is in the case of a washing machine. At the tub 2 a Einspülbehälter 5 is arranged, which can be filled with detergent. By a Inlet line 6 enters fresh water into the dispenser 5 and rinses the detergent in the tub 2. Below the tub 2, a drain pump 3 is arranged, which pumps the liquid from the tub 2 through an opening into a drain opening 43 drain line 4 through to the outside. Between the tub 2 and the drain pump 3 is an outlet valve 31, which ensures that the leaked out of the tub 2 in the drain pump 3 liquid does not flow back into the tub 2. In the case of the domestic appliance 1 considered here, there is also a vent line 7 which extends between the drain pump 3 and the dispenser 5 and ensures pressure equalization.

At the end of a washing program and optionally also between different washes of a washing program, the liquid is pumped out of the tub 2 by means of the drain pump 3. During the pumping operation, a liquid column 41 is formed in the discharge line 4. Due to gravity, the liquid column 41 generates a backpressure dependent on the height difference, against which the drain pump 3 must work in order to convey the liquid from the household appliance 1. In the Fig. 1 In addition, a return fuse 42 is shown schematically in dashed lines, which is a liquid storage. When the drain pump 3 is turned off, then a defined amount of liquid flows from the return valve 42 back into the drain pump 3 and thereby ensures that the outlet valve 31 is closed and remains. Instead of a return valve 42 in the form of such an additional element, the drain line 4 itself can be dimensioned as a return valve 42 by it can hold enough liquid to fill the lye pump 3 in the off state.

At the end of a pumping operation, the drain pump 3 is shut down in a shutdown. Usually, this is done by the energy supply to the drain pump 3 abruptly turned off and / or the drain pump 3 is also braked. As a result, the pumping power of the drain pump 3 drops abruptly from the operation pumping power to a minimum pumping power or to zero. This fact is in the Fig. 2a reproduced in the case of a designed as a rotary pump drain pump 3. The speed of the drain pump 3 falls here during the shutdown in no time from the operating speed, in this case 3500 U / min, to zero. This has the consequence that the pumping force maintained by the pumping power is immediately eliminated and the liquid column 41 located in the discharge line 4 is also abruptly accelerated downwards to the drain pump 3. In the present embodiment, since the spill valve 31 prevents the liquid from entering the tub 2, the backflowing liquid becomes in the Vent line 7 penetrate and lead to the deposition of dirt there - in the worst case up to Einspülbehälter 5 up.

In order to reduce or completely prevent the abrupt return flow, the shut-off operation of the drain pump 3 is designed such that the pumping power of the drain pump 3 is gradually reduced down to zero from the operation pumping power. This case is in the Fig. 2b exemplified, which shows a ramped shutdown of the power of the lye pump speed from the operating speed to 3500 rpm to zero. The shutdown of the performance of the drain pump, for example, gradually so that a liquid column located in the drain line does not exceed a maximum return flow rate of 0.5 meters per second (m / s) at the return flow from the drain opening 43 back to the drain pump 3. The speed of the liquid flowing back can be determined, for example, by measuring dirt particles in the liquid column 41. Alternatively, it is also possible to have an in Fig. 1 traced liquid level 44, which forms when the performance of the drain pump 3 is shut down far enough that the liquid column 3 tears off and flows down along the drain line 4.

LIST OF REFERENCE NUMBERS

1

Water-conducting household appliance

11

casing

2

tub

3

Drain pump

31

outlet valve

4

drain line

41

liquid column

42

Return valve

43

drain hole

44

liquid level

5

Induction bowl

6

inlet line

7

vent line

Claims (10)

A method for pumping a liquid from a water-conducting household appliance (1), in particular from a washing machine, in which by means of an electric lye pump (3) at an operating pumping capacity of the drain pump (3) the liquid from a tub (2) conveyed up through a drain line (4) and the pumping capacity of the drain pump (3) is then shut down in a shutdown process,
characterized,
that the shutdown process, the pumping power of the drain pump (3) is gradually carried out. Method according to claim 1,
characterized,
that during the shutdown process, a reduction rate of the pumping capacity of the drain pump (3) is limited. Method according to claim 1 or 2,
characterized,
in that, during the switch-off process, the power of the drain pump (3) is gradually reduced such that a liquid column located in the drain line at reflux along the drain line (4) has a maximum return flow of 0.5 meters per second (m / s), 0.4 m / s, 0.3 m / s, 0.25 m / s or 0.2 m / s. Method according to one of the preceding claims,
characterized,
that during shutdown the shutdown of the performance of the drain pump (3) takes place at least partially in stages and / or gradually. Method according to one of the preceding claims,
characterized,
that the shutdown of the power of the drain pump (3) is at least partially ramped. Method according to one of the preceding claims,
characterized,
that the drain pump (3) has an operating speed at BetriebsPumpleistung, wherein during the shutdown, the speed of the drain pump (3) at least temporarily per second by less than 10%, 8%, 6% or 4% of the operating speed is reduced. Method according to one of the preceding claims,
characterized,
that the drain pump (3) has an operating speed in operation of pump power, wherein upon turn-off operation, the rotational speed of the drain pump (3) at least at times to less than 200 revolutions per minute (rev / min), 150 U / min, 100 U / min or 50 U / min per second is reduced. Method according to one of the preceding claims,
characterized,
that during the shutdown process, the gradual shutdown of the performance of the drain pump (3) by a drive frequency of an electrical control of the drain pump (3) is varied. Method according to one of the preceding claims,
characterized,
that the liquid flows due to a difference in height by gravity from the tub (2) in the drain pump (3). Water-conducting household appliance, in particular washing machine, with a tub (2), a drain line, an electric drain pump (3) which is connected to the tub (2) and a drain line (4), for conveying up a liquid from the tub (2) the drain line (4), and a lye pump control device, which is designed to control the drain pump (3) for conveying the liquid from the tub (2) through the drain line (4) at a Betriebsspumpleistung and then the drain pump (3) in one Shut down shutdown,
characterized,
in that the drain pump control device is designed to gradually perform the shutdown of the power of the drain pump (3) during the switch-off process.

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