EP2701571B1 - Dishwasher and method for operating a dishwasher - Google Patents

Description

The invention relates to a dishwasher, in particular a domestic dishwasher and a method for operating a dishwasher, in particular a domestic dishwasher.

In dishwashers spraying devices are arranged in different Spülraum levels, which are assigned to different arranged in the dishwasher crockery baskets. For loading items to be cleaned in an upper dish rack and / or a cutlery drawer with a rinsing liquid - often also referred to as rinsing liquid - a ceiling spraying device, e.g. in the form of a ceiling spray arm, a roof shower or a roof gyro, and / or a top basket spray device, e.g. in the form of a top basket spray arm used. For loading items to be cleaned in a lower dish rack, a lower basket spray device, e.g. used in the form of a arranged in the bottom region of the washing compartment lower basket spray arm. The supply of the spraying devices with the rinsing liquid takes place via supply lines, wherein a pump, for example a circulating pump, feeds the rinsing liquid into the supply lines. The supply lines lead the rinsing liquid, which is conveyed by the pump, to the spray devices, from which the rinsing material in the racks is exposed to rinsing liquid.

To achieve reduced water and energy consumption, a distribution unit, e.g. in the form of a water diverter, which allows a separate supply of water to the individual spray devices or even a group of spray devices.

In order to achieve a high flushing performance and thus a good cleaning result, it is necessary to avoid foam formation in the flushing liquid during operation of the dishwasher. Foaming leads namely to a drop in the delivery pressure and thus the delivery rate of the pump and thus ultimately to a reduced flushing performance.

From the DE 10 2005 061 806 A1 a dishwashing machine with a rinsing container, devices for rinsing dishes by means of rinsing liquor, a pump for circulating the rinsing liquor and a detection means for detecting foaming in the rinsing liquor in a subprogram step "rinsing" is known, wherein in the case of a detected by the detection means foaming the Foaming can be counteracted with means, in particular a rinsing bath temperature can be increased.

The object of the invention is to provide a dishwasher, in particular domestic dishwasher, with at least two spray devices which can be supplied separately with rinsing liquid and a method for operating such a dishwasher, in which foaming in the rinsing liquid is suppressed effectively and with simple means and thus in a cost-saving manner.

This object is achieved by a dishwasher and a method for operating a dishwasher having the features of the independent claims 1 and 6, respectively.

Accordingly, a dishwasher according to the invention comprises a rinsing container for receiving items to be cleaned, at least two arranged within the rinsing sprayers for applying the rinsing material with rinsing liquid, a pump, in particular circulation pump for conveying rinsing liquid to the spray devices, controlled by a control unit distribution unit for distribution the conveyed rinsing liquid to a single or a group of spray devices, wherein a volume flow of the rinsing liquid is adjusted depending on the distribution of the rinsing liquid on the spray devices. In addition, the dishwasher has a detection device for detecting foaming in the rinsing liquid. Upon detection of foaming in the rinsing liquid, the control unit controls the distributor unit in such a way that the distribution of the rinsing liquid on the spray devices changes in such a way that the tendency for foam formation to decrease.

According to the inventive method for operating a dishwasher with at least two arranged within a washing container spray devices for applying to be washed items with rinsing liquid and with a pump, in particular circulation pump, for conveying rinsing liquid to the spray devices, wherein the conveyed rinsing liquid by means of a distribution unit to a single or a group of spray devices can be distributed and adjusts depending on the distribution of the rinsing liquid on the spraying a volumetric flow of the rinsing liquid, foaming is detected in the rinsing liquid and the distribution unit is controlled in detection of foaming in the rinsing liquid such that the distribution of the rinsing liquid to the spray devices changed so that the tendency to foaming is reduced.

The invention is based on the basic idea that the tendency to foaming is actively influenced by a changed distribution of the rinsing liquid to the individual spraying devices due to the thus changed liquid paths and / or the resulting changed impact characteristics of downwardly flowing rinsing liquid on the bottom or sieve region of the rinsing container can. So can be reduced by a simple change to another spray the tendency to foam or even eliminated completely. Such operating phases thus act in terms of foaming as calming phases in which no new foam is formed and in which the already existing foam degrades again.

According to one embodiment of the invention, the distributor unit is controlled by the control unit upon detection of foaming in the rinsing liquid such that a volume flow of the rinsing liquid which is reduced in comparison to a current volume flow is also established.

If the volume flow of the rinsing liquid is too high in view of a currently available rinsing fluid quantity, the pump sucks in air, which is thus fed into the rinsing fluid circuit. However, an excessively high proportion of air promotes foaming, in particular in conjunction with a high dirt concentration and / or a rinse aid mixed with the rinsing liquid. By reducing the volume flow, the intake of air can be prevented or at least mitigated to a degree which does not lead to any further foaming. The operation with Reduced flow thus also represents a kind of calming phase, in which no new foam formed and in which the existing foam decreases again. The reduction of the volume flow of the rinsing liquid is achieved in a particularly simple and thus cost-effective manner that with the aid of a distribution unit, for example in the form of a water diverter, a change to another spray device is made, automatically adjusts a lesser volume flow in the loading of rinsing liquid , The lower volume flow can result, for example, from a smaller number of outlet openings for the rinsing liquid and / or reduced diameters of the outlet openings at the spray devices. The different installation height of the individual spray devices and / or different cross-sections of the supply lines have an effect on the respectively adjusting volume flow. A change in other operating parameters, such as the pump speed, can be made to further support the foam suppression, but is generally not required.

Particularly advantageously, the invention can be used in dishwashers, in which an alternate feeding of individual spray devices or groups of spray devices with rinsing liquid is provided anyway. In this case, the foam suppression according to the invention even allows, in a maximum flow mode, e.g. in lower basket operation, in which the rinsing liquid is distributed exclusively to a lower basket spraying device, to allow a predeterminable amount of air bound into the rinsing fluid circuit. The activation of the distributor unit according to the invention in the detection of foaming ensures that in good time before an excessive drop in the delivery pressure and thus the delivery rate of the pump to another operating mode, e.g. Upper basket operation and / or ceiling operation, with a lesser tendency to foaming and possibly also a reduced flow rate is changed.

According to one embodiment of the invention, the detection device comprises a sensor system which detects at least one operating parameter of the pump or of a drive unit associated with the pump, eg in the form of an electric motor, wherein the at least one operating parameter is dependent on a proportion of foam in the conveyed rinsing liquid. Foaming in the rinsing liquid can then be detected in this case if the at least one operating parameter or a variable derived therefrom reaches a predefinable limit value.

As operating parameters which indirectly make it possible to infer the foaming in the rinsing liquid, the pump speed and / or the pump pressure and / or the noise radiation emitted by the pump and / or the absorbed active power of the pump can be used. Accordingly, the detection device is designed to determine the pump speed and / or the pump pressure. Alternatively or additionally, the detection device is for detecting the noise radiation emitted by the pump, e.g. Volume or audio frequency, formed.

The indirect determination of the foaming on the determination of an operating parameter of the pump or the associated drive unit can be structurally particularly simple accomplish. If foaming occurs in the rinsing liquid, which is supplied to circulate the pump, this is reflected in a decreasing pump pressure and at the same time in an increasing rotational speed of the pump. As a result, the operating noise of the pump, e.g. Volume or tone frequency.

The pump speed can be determined via an arbitrarily designed speed sensor. If the speed of the pump can be controlled or regulated, then no additional speed sensor need be provided, since the speed can be sensed by the pump itself. In this way, additional costs can be avoided.

Alternatively, however, there is also an immediate detection of foaming, e.g. conceivable with the aid of optical and / or chemical sensors.

The evaluation unit can be advantageously integrated into the control unit for controlling the distribution unit, but can also be designed as an independent unit or integrated into the sensor system.

According to a specific embodiment of a dishwasher according to the invention, at least one lower-basket spraying device is located inside the washing container and on the other hand at least one upper basket spraying device and / or a ceiling spraying device arranged. In this case, the control unit controls upon detection of foaming in the rinsing liquid, the distributor unit such that the rinsing liquid is distributed to the upper-basket spraying device and / or the ceiling spray device. By changing in this way, in particular also extended fluid paths and the changed impact characteristics of the downwardly flowing rinsing liquid on the bottom or sieve region of the washing compartment, the tendency for foaming thereby decreases. Advantageously, when the lower-basket spraying device is acted upon, a higher volume flow of the rinsing liquid is produced than when the upper-basket spraying device and / or the ceiling spraying device are acted upon, so that the volume flow is automatically reduced by the replacement of the spraying device.

A corresponding operating method provides that, when in a lower basket operation, in which the rinsing liquid is distributed exclusively to the lower basket spray device, foam formation is detected, the distribution unit is controlled such that is changed from the lower basket operation in a Oberkorb- and / or ceiling operation , In this case too, it is advantageous if, in upper basket operation, in which the rinsing liquid is distributed exclusively to an upper basket spraying device and / or in ceiling operation, in which the rinsing liquid is distributed exclusively to a ceiling spraying device, sets a lower volume flow than in the lower basket operation ,

In order to suppress foaming particularly effectively, it is provided according to a further embodiment of the invention to control the distributor unit in the detection of foaming in the rinsing liquid such that sets a minimum possible volume flow of the rinsing liquid. Thus, for example, in foam detection in sub-basket operation can be switched to a ceiling operation, if set in the ceiling operation, a lower flow rate than in a top basket operation.

A particularly effective suppression of foaming with simultaneous optimal cleaning performance can be achieved in this case, that the distributor unit is controlled in detected foaming in lower basket operation such that first for a first period in the ceiling operation and then changed for a second period in the upper basket operation ,

In order to suppress foaming permanently, it is provided according to a further embodiment of the invention, to change from the upper basket and / or ceiling operation at the earliest after a predetermined period of time again in the lower basket operation.

Further support in the suppression of foam formation can finally be achieved by reducing the speed of a drive unit associated with the circulation pump in comparison to the previous lower basket operation when changing back to the lower basket mode.

Fig. 1

eine schematische Darstellung einer erfindungsgemäßen Geschirrspülmaschine,

Fig. 2

einen schematischen zeitlichen Verlauf des Volumenstroms der Spülflüssigkeit bei Einsatz eines erfindungsgemäßen Betriebsverfahrens gemäß einer ersten Ausführungsform und

Fig. 3

einen schematischen zeitlichen Verlauf des Volumenstroms der Spülflüssigkeit bei Einsatz eines erfindungsgemäßen Betriebsverfahrens gemäß einer zweiten Ausführungsform.

Further features and advantages of the invention will be explained below with reference to embodiments with reference to the accompanying figures. Show it:

Fig. 1

a schematic representation of a dishwasher according to the invention,

Fig. 2

a schematic time profile of the volume flow of the rinsing liquid when using an operating method according to the invention according to a first embodiment and

Fig. 3

a schematic time profile of the volume flow of the rinsing liquid when using an operating method according to the invention according to a second embodiment.

In Fig. 1 is a dishwasher with a, a Spülraum limiting rinse tank 1 shown. In the washing compartment of the washing container 1, a not-shown items to be cleaned can be arranged in dish racks in the form of a lower basket 3 and an upper basket 5. In the washing container 1 shown, three spraying devices provided in different spraying levels are arranged in the form of a lower basket spraying device 7, an upper basket spraying device 8 and a ceiling spraying device 9, via which the washware to be cleaned is supplied with washing liquid. The lower basket spraying device 7 and the upper basket spraying device are exemplified as spray arms and the ceiling spraying device 9 exemplified as a shower head. In Spülbehälterboden is a pump pot 10 with only roughly indicated Screen assembly 11 is provided. Starting from the pump pot 10, a circulation line 12 with pump 13 arranged therein is led away in the form of a circulating pump 13 'and a downstream water heater 14. Downstream of the water heater 14, a distributor unit 15 in the form of a water distributor 15 'is provided, at which three supply lines 16 branch off from the circulation line 12. About the supply lines 16, the circulation line 12 is connected to the spray devices 7, 8, 9. The water diverter 15 'serves to distribute the rinsing liquid conveyed by the circulating pump 13' to a single or also to a group of the spraying devices 7, 8, 9. Due to a different design and arrangement of the individual spraying devices 7, 8, 9 and / or the Feed lines 16 are dependent on the position of the water switch 15 'and the resulting distribution of the washing liquid on the spray devices 7, 8, 9 different volume flows. The respective position of the water switch 15 'is determined by a control unit 17 which controls the water switch 15'.

The rinsing liquid sprayed out of the spray devices 7, 8, 9 collects on the rinsing container bottom and is introduced again via the sump 10 into the recirculation line 12, so that a liquid circuit is formed. At the sump 10 also connected to the water supply network fresh water supply line 18 and a drain line 19 is provided, in which a drain pump 20 is arranged for pumping out rinsing liquid from the washing compartment 1. In the fresh water supply line 18, a water inlet valve 19 is arranged.

To carry out a rinse cycle, the dishwasher has a program control device 21 with which known program steps, such as pre-rinsing, cleaning, intermediate rinsing, rinsing and / or drying, can be carried out. For this purpose, the program control device 21 can control the respective device components via signal lines shown in dashed lines.

How out Fig. 1 Furthermore, the circulation pump 13 'is assigned a drive unit 22 in the form of an electric motor 22', which drives the circulation pump 13 'via a drive shaft 23. The electric motor 22 'can be designed, for example, as a so-called BLDC motor, that is, brushless DC motor. The electric motor 22 'may also be associated with an unillustrated inverter or inverter, the Electric motor 22 'supplied with electrical energy. The inverter or inverter generates the required electrical three-phase voltage for the electric motor 22 ', ie an electrical voltage with the required frequency and required RMS value. About the inverter or inverter, the program control device 21, the electric motor 22 'of the circulation pump 13' control, if necessary, also regulate.

By a sensor 24, an operating parameter of the electric motor 22 ', such as e.g. the speed can be detected during pump operation. The operating parameter thus detected is conducted via a signal line 25 to an evaluation unit 26 and evaluated there. In the illustrated embodiment, the evaluation unit 26 is integrated into the program control device 21. Alternatively, however, the evaluation unit 26 can also be realized separately or integrated into the sensor system 24.

The operating parameters detected by the sensors 24, e.g. the speed of the electric motor 22 'is dependent on a proportion of foam in the conveyed rinsing liquid. As such, by comparing the operating parameter or a quantity derived therefrom, e.g. the fluctuation range of the operating parameter or the pump power, with a threshold value, a foaming in the rinsing liquid can be detected. In addition to the speed of the electric motor mentioned by way of example, basically any desired operating parameter of the circulating pump 13 'or the associated electric motor 22' for detecting foaming in the rinsing liquid can be detected and evaluated, provided that the operating parameter changes as a function of the proportion of foam in the rinsing liquid.

The sensor 24 thus forms, together with the evaluation unit 26, a detection device 27 for detecting foaming in the rinsing liquid.

As an alternative to detecting the formation of foam via an operating parameter of the circulating pump 13 'or of the associated electric motor 22', it is of course also possible to use a sensor system which directly detects the foaming.

To explain the operating method according to the invention, it is assumed in the following that, in a lower basket operation, in which the rinsing liquid is distributed exclusively to the lower basket spray device 7, due to the embodiment and Arrangement of the lower basket spray device 7 and / or the associated feed power 16 sets a maximum flow rate of the rinsing liquid. Correspondingly, in the upper basket mode, in which the rinsing liquid is distributed exclusively to the upper basket spraying device 8, a medium volume flow and in the ceiling mode, in which the rinsing liquid is distributed exclusively to the ceiling spray device 9, a minimum volume flow. Furthermore, it is assumed by way of example that in sub-basket operation, a predeterminable proportion of air in the rinsing liquid should be permissible.

An inventive operating method according to a first embodiment is described below with reference to FIG. 2 explains which shows schematically the time course of the volume flow of the rinsing liquid. In a first time phase beginning with the time T0, the dishwasher is operated in lower basket operation. This results in a maximum volume flow Q1. Due to the high volume flow and the permissible air content in the lower basket operation, foaming in this operating mode can not be ruled out. An increased concentration of dirt, especially when using rinse water in a known intermediate storage of rinsing liquid (fleet storage technology), increases the tendency to foaming especially in a part program step "cleaning" in addition.

From the time T1 results in a non-circular operation of the circulation pump 13 'and concomitantly a drop in the volume flow with a simultaneous increased fluctuation range, which is due to foaming in the rinsing liquid. This foaming also has an effect on the operating parameters of the circulation pump 13 'and the associated electric motor 22', such as the rotational speed of the electric motor 22 ', so that the foam formation can be detected with the aid of detection means in the form of the sensor system 24 and the evaluation unit 26. After detection of the foaming is changed at time T2 from the upper basket operation in the ceiling operation. For this purpose, the water switch 15 'by the associated control unit 17, which is realized in the illustrated embodiment as part of the program control device 21, but which can also be realized separately, so controlled that the rinsing liquid is distributed exclusively to the ceiling spray device 9. As a result, the volume flow abruptly drops to a minimum value Q2. The reduced volume flow leads to a significant reduction of the air content in the rinsing liquid and thus to avoid further foaming. Rather, the already formed foam is reduced again. The ceiling operation In this respect, foaming acts as a calming phase, in which the foam formed can degrade again. After a first period of time Δt1 is changed at a time T3 from ceiling operation in the upper basket operation, in which sets a mean volume flow Q3. For this purpose, the water switch 15 'is again controlled by the control unit 17 accordingly.

Also, the average volume flow Q3 leads in comparison to the high volume flow Q1 during the lower basket operation to a reduction of the air content in the washing liquid, in which further foaming is avoided and in which already formed foam can degrade again. In this respect, the upper basket operation still acts as a calming phase with regard to foam formation.

After a second period .DELTA.t2 is changed at the time T4 from the upper basket operation again in the lower basket operation. From then on the sequence shown and described repeats periodically. A third time interval .DELTA.t3 between two Unterkorbbetrieberi, which is composed in the illustrated embodiment of the two periods .DELTA.t1 and .DELTA.t2 is set such that the already formed foam is degraded again at least to such an extent that sufficient Spülleistung be achieved in the course of the rinsing process can.

FIG. 3 shows schematically the time course of the volume flow of the rinsing liquid when using an operating method according to the invention according to a second embodiment. The second embodiment differs from the first embodiment only in that after a renewed change to the lower basket operation at time 4, the speed of the circulating pump 13 'associated electric motor 22' is reduced compared to the previous lower basket operation in the period between T0 and T2, which manifests itself in a volume flow Q1 'reduced to the maximum volume flow Q1. If necessary, this reduction in the speed can also be continued over several periods, as shown.

The invention has been described by way of example for a dishwashing machine in which different volume flows of the washing liquid result in lower basket operation, in upper basket operation and in ceiling operation, which supports the desired suppression of foam formation. It should be expressly understood, however, that the invention Basically, regardless of a change in the volume flow can be used, since even the changed fluid paths and / or the resulting changed impact characteristics of the flowing down flushing liquid on the container bottom can cause the desired suppression of foaming.

Used reference signs

1

rinse tank

3

lower basket

5

upper basket

7

Lower rack sprayer

8th

Upper basket spray device

9

Ceiling spray

10

sump

11

sieve

12

circulation line

13

pump

13 '

circulating pump

14

water Heating

15

distribution unit

15 '

water points

16

supply lines

17

control unit

18

Fresh water supply

19

Water inlet valve

20

Drain pump

21

Program control device

22

drive unit

22 '

electric motor

23

drive shaft

24

sensors

25

signal line

26

evaluation

27

detection device

Claims (15)

1. Dishwasher, in particular domestic dishwasher, having

   - a dishwashing cavity (1) for receiving wash items to be cleaned,

   - at least two spraying devices (7, 8, 9) arranged inside the dishwashing cavity (1) for applying wash liquor to the wash items,

   - a pump (13), in particular circulating pump (13'), for conveying wash liquor to the spraying devices (7, 8, 9),

   - a control unit (17),

   - a detection facility (27) for detecting a formation of foam in the wash liquor, characterized in that the dishwasher furthermore has

   - a distribution unit (15) controlled by the control unit (17) for distributing the conveyed wash liquor to a single or a group of spraying devices (7, 8, 9), wherein a volume flow of the wash liquor is set as a function of the distribution of the wash liquor to the spraying devices (7, 8, 9),

   wherein the control unit (17) is designed such that upon detection of a formation of foam in the wash liquor, it controls the distribution unit (15) such that the distribution of the wash liquor to the spraying devices (7, 8, 9) changes such that the tendency towards the formation of foam decreases.
2. Dishwasher according to claim 1, wherein upon detection of a formation of foam in the wash liquor, the control unit (17) controls the distribution unit (15) such that a reduced volume flow of the wash liquor is set in comparison to a current volume flow.
3. Dishwasher according to one of claims 1 or 2, wherein the detection facility (27) comprises sensor technology (24) which acquires at least one operating parameter of the pump (13) or of a drive unit (22) assigned to the pump (13), wherein the at least one operating parameter is dependent on a foam content in the conveyed wash liquor.
4. Dishwasher according to claim 3, wherein the detection facility (27) comprises an evaluation unit (26), which detects a formation of foam in the wash liquor if the at least one operating parameter or a variable derived therefrom reaches a predeterminable limit value.
5. Dishwasher according to one of claims 1 or 2, wherein the detection facility (27) comprises sensor technology, in particular at least one chemical or optical sensor, which directly detects a formation of foam in the wash liquor.
6. Dishwasher according to one of the preceding claims, wherein

   - at least one lower-basket spraying device (7) is arranged inside the dishwashing cavity (1),

   - at least one upper-basket spraying device (8) and/or a ceiling spraying device (9) are arranged inside the dishwashing cavity and

   - upon detection of a formation of foam in the wash liquor, the control unit (17) controls the distribution unit (15) such that the wash liquor is distributed to the upper-basket spraying device (8) and/or the ceiling spraying device (9).
7. Dishwasher according to claim 6, wherein

   - a higher volume flow of the wash liquor is set for application by the lower-basket spraying device (7) than for application by the upper-basket spraying device (8) and/or the ceiling spraying device (9).
8. Method for the operation of a dishwasher, in particular a domestic dishwasher, having at least two spraying devices (7, 8, 9) arranged inside a dishwashing cavity (1) for applying wash liquor to wash items and having a pump (13), in particular circulating pump (13'), for conveying wash liquor to the spraying devices (7, 8, 9), wherein the conveyed wash liquor can be distributed to a single or a group of spraying devices (7, 8, 9) by means of a distribution unit (15) and a volume flow of the wash liquor is set as a function of the distribution of the wash liquor to the spraying devices (7, 8, 9), wherein

   - a formation of foam in the wash liquor is detected and

   - upon detection of a formation of foam in the wash liquor, the distribution unit (15) is controlled such that the distribution of the wash liquor to the spraying devices (7, 8, 9) changes such that the tendency towards the formation of foam decreases.
9. Method according to claim 8, wherein upon detection of a formation of foam in the wash liquor, the distribution unit (15) is controlled such that a reduced volume flow of the wash liquor is set in comparison to a current volume flow.
10. Method according to claim 9, wherein upon detection of a formation of foam in the wash liquor, the distribution unit (15) is controlled such that a minimum possible volume flow of the wash liquor is set.
11. Method according to one of claims 8 to 10, wherein

    - at least one operating parameter of the pump (13) or of a drive unit (22) assigned to the pumps (13) is acquired, which operating parameter is dependent on a foam content in the conveyed wash liquor and

    - a formation of foam in the wash liquor is detected if the at least one operating parameter or a variable derived therefrom reaches a predeterminable limit value.
12. Method according to one of claims 8 to 10, wherein a formation of foam in the wash liquor is directly acquired with the aid of sensor technology, in particular at least one chemical or optical sensor.
13. Method according to one of claims 8 to 12, wherein the distribution unit (15) is controlled such that there is a change from a lower-basket operation, in which the wash liquor is only distributed to a lower-basket spraying device (7), to an upper-basket operation, in which the wash liquor is only distributed to an upper-basket spraying device (8), and/or a ceiling operation, in which the wash liquor is only distributed to a ceiling spraying device (9), if a formation of foam is detected during lower-basket operation.
14. Method according to claim 12, wherein a lower volume flow is set during upper-basket operation and/or during ceiling operation than during lower-basket operation.
15. Method according to claim 14, wherein

    - a lower volume flow is set during ceiling operation than during upper-basket operation, and

    - the distribution unit (15) is controlled such that there is initially a change to ceiling operation for a first period of time and subsequently a change to upper-basket operation for a second period of time if a formation of foam is detected during lower-basket operation.

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