EP3214990B1 - Dishwasher comprising a drying unit - Google Patents

Description

The invention relates to a dishwasher, in particular a household dishwasher, with a washing compartment for cleaning dishes, glasses, cutlery or similar items to be washed, wherein during at least one drying phase or another process phase within a program sequence, air can be introduced into the washing compartment via at least one inlet opening, in particular a blow-out opening .

Such support for the drying of the items to be washed by blowing air into the washing compartment is known in principle, for example from WO 2010/012659 A2 . According to the DE 10 2005 023 428 A1 it is known that the conveying power of a fan varies during the dishwashing drying cycle of a commercial dishwasher, it being expressly provided that the delivery line of the fan should be reduced at the beginning of the dishwashing drying cycle.

Even with the dishwasher US 2014/0223761 A1 is to be set in the drying phase, initially with maximum steam occurring at the start of drying, a low speed of a fan that is arranged in a circulating air duct.

The invention is based on the problem of further improving or optimizing the drying of items to be washed in the interior of the washing compartment of a dishwasher, in particular domestic dishwasher, during at least one drying phase of a program sequence with as little effort as possible.

If necessary, this should also apply to another process phase in which air flows into the washing container through at least one inlet opening, in particular a blow-out opening.

The invention solves this problem with a dishwasher having the features of claim 1. Further advantages and developing features as well as developments of the invention are specified in claims 2 to 17, the features of which can each be implemented individually or in combination with one another.

The fact that, according to claim 1, the volume flow of air that can be introduced or supplied through the at least one inlet opening, in particular exhaust opening, for drying the items to be washed varies or fluctuates several times over the course of the drying phase (viewed), resulting in the course of the drying phase over time in Rinsing tank considers flow conditions that have changed several times. The volume of air introduced through the inlet opening into the interior of the washing compartment per unit of time changes several times over the duration of the drying phase. In this way, for example, such phases or periods of time in which the airflow encounters a barrier (for example a bulky or awkwardly arranged piece of crockery) can be replaced by phases in which the airflow runs past this barrier. In particular, the volume flow from a first time section or point in time to a next, second time section or point in time of the chronological progression of the drying phase has a specifically assigned volume flow value in each case.

The variation of the volume flow over the duration of the drying phase can take place in particular with such steep flanks that gush-like or pulse-like introductions of drying air into the washing container result.

Flow loading or flow changing means are preferably provided in such a way that volume flow fluctuations of the air flow introduced into the washing container are caused in a targeted manner, in particular in a predeterminable manner, over the duration of the respective drying phase. As a result, local areas or zones in the interior volume of the washing container can be better reached by the air flow introduced into the washing container by means of at least one inlet opening, or even a larger volume in the washing container can be swept by moving air or an air flow than is the case with one over the entire drying phase constant or stationary, ie constant volume flow would be possible. The drying results of the washing items drying after the end of the drying phase are thus significantly improved in the dishwasher according to the invention.

In the alternative version according to claim 1, the same advantages as in the first embodiment according to claim 1 are achieved in that the outlet speed of the air that can be introduced into the washing container at the inlet opening, in particular the blow-out opening, varies several times over the drying phase. If the cross section of the inlet opening, in particular the exhaust opening, remains the same, which is the simplest solution in terms of design, the change in speed is accompanied by a change in volume flow, so that these features of claim 1 are combined. For example, with a high velocity component in the transverse direction, the air is conveyed far away from the outlet opening, for example in the region of an opposite corner in the washing compartment, so that items to be washed which are removed are also effectively dried. With a low exit speed, on the other hand, the drying air rises more in the vicinity of the exit opening. With the speed reduction in between, the average noise level during the drying phase is also reduced compared to a permanently maximum exit speed.

In particular, the local flow distribution of the air in the washing compartment during the drying phase is varied multiple times during the specified period of time of the drying phase by the multiple variation of the volume flow and/or the exit speed of the air entering the washing compartment via the at least one inlet opening, in particular exhaust opening. In this way, different flow profiles come into effect in the washing container over the drying phase in any case and independently of any sensor technology (which is entirely dispensable). Flow vectors that vary in terms of amount and/or direction at each point or location in the treatment space or interior of the washing compartment are thus advantageously produced selectively during the drying phase.

If the multiple variation or change in the volume flow and/or the exit speed over the duration of the respective drying phase is controlled by a sequence program, readjustment is not necessary. The invention therefore shows a high degree of simplicity.

In particular, the multiple variation or change in the volume flow and/or the exit speed is possible via a control device stored in a preferably electrical control device, in particular a control unit, of the dishwasher The program is permanently preset and therefore does not require any external input data, which opens up the above-mentioned option of completely dispensing with sensors.

The dishwasher according to the invention thus allows for improved drying of items to be washed in a simple manner, without the use of a sensor, such as a moisture sensor, assigned to the washing compartment being necessary. It is now possible, even in areas in the interior of the washing compartment that are shaded or covered by the respective items to be washed in a sufficient manner in order to achieve sufficient removal of any moisture present there during the drying phase. With regard to its drying, the dishwasher according to the invention is thus noticeably more independent of the type of items to be washed, the load quantity items to be washed, and/or how the washing compartment is filled with items to be washed. For example, oversized plates, pots or the like impair the inflow of moving air far less than before, even in an area that is not in the direct line of sight to the outlet or outflow opening, but is covered or obstructed by items to be washed, such as a large plate. is shadowed. The air can thus be distributed more evenly than before in the interior of the washing compartment over the entire duration of the respective drying phase. In this way, perfect, effective drying of the items to be washed is always ensured (for a predetermined total time for the drying phase) in a large number of loading situations and/or loading constellations of the washing compartment with items to be washed. This can be achieved in a particularly energy-efficient manner when using a sorption drying device. If desired, however, the drying time can even be shortened without too great a loss in terms of drying performance and/or energy efficiency.

The invention works in an advantageous manner with different types of drying, for example also with circulating air drying, exhaust air drying and/or condensation drying.

In particular, however, the dishwasher can also be provided with a sorption drying device. During the drying phase, air that has passed through the sorption drying device and has given off liquid to the sorbent there via adsorption can then be introduced into the rinsing container and bring about a high degree of drying. Then it is particularly favorable to work with a high volumetric flow rate and/or a high discharge speed in the initial phase, i.e. during the initial time of the drying phase in which the drying air transports a particularly large amount of moisture away, which and/or during the further course of the drying phase overall can be reduced.

Since according to the invention the variation of the volume flow and/or the exit speed can be (also) effected via different speeds of a blower upstream of the exhaust opening, the structural design and the controllability of such an air flow impinging or flow changing means are simple and inexpensive. The speed of the blower is variably preset, in particular via the program sequence, so that no sensors are required for input data. A simple control is sufficient without having to provide a control loop.

According to the invention, the speed of the blower during the drying phase or another process phase - outside of a start-up phase and a run-down phase of the blower - is kept in a (speed value) interval between at least one, in particular specifiable, maximum and at least one minimum speed, so it is not noticeable Zero, so that the drying time is used effectively. In the respective speed value interval, a large number of other speed values can of course be approached and varied as speed maximums and minimums. The interval can be selected in such a way that the average noise level falls below a set limit value. Due to the independence of the control, the noise level is always the same.

According to the invention, the speed at the beginning of the drying phase is first raised to a maximum speed and then reduced to a minimum speed of the interval. The amount of water to be discharged at the beginning of the drying phase is particularly high in the case of the sorption devices mentioned above. This can be taken into account by the particularly high rotational speed initially during an initial period of the drying phase or the drying cycle.

The respectively selected minimum speed (lowest value) and maximum speed (highest value) of the speed change range defined for the speed variation is preferably outside the speed range that occurs when the blower is initially started up or stopped. The minimum speed is selected in particular from a speed range other than zero revolutions per minute (=rpm ("rounds per minute")), from which the fan can set a desired operating speed in a defined manner. Tests have shown that for the fan types commonly used in dishwashers for drying, only a speed of at least 1500 revolutions per minute is favorable for control engineering reasons. This is because many fans that have a so-called PMSM (permanent magnet synchronous motor) electric motor can only be set, in particular regulated, to a desired speed from 1500 revolutions per minute. A value between 3000 and 4000 revolutions per minute is preferably selected for the first, lower target speed to be set (lowest value of the speed variation interval). A value that is at least 5000 revolutions per minute, in particular between 5000 and 6000 revolutions per minute, is expedient for the second, upper setpoint speed (maximum value of the speed variation value interval). The distance between the lower or lower speed and the upper, higher speed is selected in particular to be more than 1000 revolutions per minute. A speed variation between the minimum and maximum values is advantageously selected in such a way that it falls within a range of auditory perception that users of dishwashers perceive or accept as uncritical.

If, according to an advantageous development of the invention, the speed of the blower during the drying phase is at least twice the (speed value) interval between Passing through maximum and minimum speed, a large change in the air flow can be brought about, so that the most varied local distributions of the (air) flow are realized in the rinsing tank. This means that the speed of the blower changes several times between a first (non-zero) target speed and a different, second (non-zero) target speed during the duration of the drying phase, ie is varied.

In particular, with the blower 2-10 changing between a preferably specifiable, lower setpoint speed and a preferably specifiable, upper setpoint speed over the entire duration of the drying phase of the respective wash cycle can be expedient in order to achieve a change or variation desired to improve the drying performance of the dishwasher to bring about the local air flow distribution in the interior of the rinsing tank to a sufficient extent. The period of time for the change between the first target speed and the second target speed, which differs therefrom, is expediently at least 30 seconds, in particular between 1 minute and 5 minutes.

The speed curve can be variable over at least part of the drying phase in the manner of a sawtooth or sine curve between one or more maximum and minimum values, so that the speed changes constantly from one moment to the next. Alternatively, it is also possible for the speed profile to be variable over at least part of the drying phase in the manner of a step function between one or more maximum and minimum values. Then, at the beginning, for example, a time typically in the range of minutes can be left at the highest speed level in order to drain off a particularly large amount of water.

The respective lowest value of the target speed is more than 5% below the respective maximum value of the target speed and thus clearly above any tolerance fluctuations of a speed-controlled motor.

In particular, the lowest values of the speed are more than 1000 revolutions per minute below the highest values in order to achieve large differences in the local flow distribution.

In addition or as an alternative to the speed variation, the volume flow and/or the exit speed can also be varied via at least one controllable closure element assigned to the inlet opening, in particular the exhaust opening, such as a sector disk with one or more rotating in the air flow downstream of the blower open and closed areas.

In this case, the open areas can be of different sizes over the circumference, in order to also allow a high passage and a high volume flow at the beginning, which can then become smaller in the course of the drying phase.

At least one movable mechanical control means, such as an air baffle, a nozzle with variable direction, a movable flap or the like, can also be assigned to the outlet opening. The direction of the air blown in can thus be changed, as can the outlet cross-section, so that variations are also possible here.

According to an expedient development of the invention, the inventive variation of the volume flow and/or the exit speed of the air that enters the washing chamber of the washing compartment from the respective inlet opening, in particular exhaust opening, can also be used in one or more further process phases of the dishwasher, in particular when a dishwasher program is running be performed. Another such process phase can be a desorption phase, for example, in a dishwasher equipped with a sorption drying device. This can be carried out advantageously in terms of energy in a partial wash cycle, such as the cleaning cycle with dishwashing liquid to be heated, because then the heat energy applied for desorption by a heating device can also be used to heat up dishwashing liquid of a partial wash cycle, such as a cleaning cycle, of the rinse cycle of a dishwashing program can. By varying the volume flow and/or the exit speed, the air exiting the inlet opening into the washing compartment, which is heated by a heating device used for desorption, can advantageously sweep over a larger spatial area of the washing compartment enclosed by the washing compartment and the door and/or heat the treatment space enclosed by the wash tub and the closed dishwasher door more evenly than this would previously have been possible with a volume flow and/or exit velocity that remained constant over the entire desorption period. In particular, this can result in higher energy efficiency and/or heating-up speed of the washing compartment.

Other developments of the invention are given in the dependent claims.

The advantageous constructions and developments of the invention explained above and/or reproduced in the subclaims can - apart from e.g. B. in cases of clear dependencies or incompatible alternatives - can be used individually or in any combination with each other.

Fig. 1

eine schematisch dargestellte Geschirrspülmaschine in perspektivischer Ansicht von schräg vorne bei teilweise geöffneter Tür,

Fig. 2

eine schematische Ansicht eines herausgezeichneten Spülbehälters von schräg vorne mit einem in der hinteren rechten Ecke gelegenen Ausblasöffnung für in der Trocknungsphase den Innenraum des Spülbehälters beaufschlagende Luft,

Fig. 3

einen möglichen Drehzahlverlauf eines Gebläses zur Luftbeaufschlagung der Ausblasöffnung während der Trocknungsphase,

Fig. 4

einen weiteren möglichen Drehzahlverlauf eines Gebläses zur Luftbeaufschlagung der Ausblasöffnung während der Trocknungsphase,

Fig. 5

ein Diagramm der Wasseraufnahmefähigkeit von Zeolith als Sorptionstrocknungsmittel über die Zeit,

Fig. 6

ein Diagramm der gemessenen Ausblastemperatur der Luft in der Adsorptionsphase,

Fig. 7

eine Ansicht von der Vorderseite in einen befüllten Spülbehälter mit eingezeichneten Strömungspfeilen einer Luftströmung während der Trocknungsphase,

Fig. 8

eine ähnliche Ansicht wie Figur 7 mit einer alternativen Strömungsverteilung,

Fig. 9

eine ähnliche Ansicht wie Figur 7 mit einer alternativen Strömungsverteilung,

Fig. 10

eine ähnliche Ansicht wie Figur 7 mit einer alternativen Strömungsverteilung,

Fig. 11

eine Detailansicht einer Ausblasöffnung mit einem vorgeschalteten Verschlußglied, und

Fig. 12

ein schematisches Gesamtschaltbild eines Spülbehälters mit einer Luftauslaßleitung, einem Gebläse und einem Sorptionstrocknungsbehälter vor einer Ausblasöffnung.

The invention and its advantageous training and further developments as well as their advantages are explained in more detail below with reference to drawings showing exemplary embodiments. They show, each in a schematic principle sketch:

1

a schematically illustrated dishwasher in a perspective view obliquely from the front with the door partially open,

2

a schematic view of a drawn-out washing compartment diagonally from the front with an exhaust opening located in the rear right-hand corner for air that acts on the interior of the washing compartment in the drying phase,

3

a possible speed curve of a blower for air loading of the exhaust opening during the drying phase,

4

Another possible speed curve of a fan for air loading of the exhaust opening during the drying phase,

figure 5

a diagram of the water absorption capacity of zeolite as a sorption drying agent over time,

6

a diagram of the measured outlet temperature of the air in the adsorption phase,

7

a view from the front into a filled rinsing container with drawn flow arrows of an air flow during the drying phase,

8

a similar view as figure 7 with an alternative flow distribution,

9

a similar view as figure 7 with an alternative flow distribution,

10

a similar view as figure 7 with an alternative flow distribution,

11

a detailed view of a blow-out opening with an upstream closure member, and

12

a schematic overall circuit diagram of a rinsing tank with an air outlet line, a blower and a sorption drying tank in front of a blow-out opening.

Elements with the same function and mode of operation are each provided with the same reference symbols in the figures. In this case, only those components of a household appliance which are necessary for understanding the invention are provided with reference symbols and explained.

In the figure 1 Dishwasher 1 shown schematically is a household dishwasher and, as part of a body 5, has a washing compartment 2 for accommodating items to be washed, such as crockery, pots, cutlery, glasses, cooking utensils, and the like. The items to be washed can be held, for example, in crockery baskets 11 and/or a cutlery drawer 10 and can be acted upon by washing liquor. The washing container 2 can have an at least essentially rectangular outline having a front side VS facing a user in the operating position. The front VS can form part of a kitchen front made of kitchen furniture standing next to one another or, in the case of a stand-alone appliance, can also be unrelated to other furniture.

The loading opening of the rinsing tank can be closed with a door. Here in the exemplary embodiment, a front loading opening of the washing compartment 2 on the front side VS of the dishwasher can be closed by a door 3 . This door 3 is in figure 1 shown in a partially open position and then at an angle to the vertical. In its closed position, on the other hand, it stands upright approximately vertically. According to the drawing, it can be pivoted forwards and downwards in the direction of arrow 4 about a horizontal axis that is lower in relation to the front loading opening of the washing compartment, so that it is at least almost horizontal in the fully open position. The walls of the washing compartment and the closed door enclose a treatment or washing chamber in which the items to be washed to be cleaned and/or dried can be accommodated.

On its outer and front side VS, which is vertical in the closed position and faces the user, the door 3 can be provided with a decorative panel 6 in order to experience a visual and/or haptic enhancement and/or an adaptation to the surrounding kitchen furniture.

The dishwasher 1 is designed here as a stand-alone device or as a so-called partially integrated or fully integrated device.

The movable door 3 is in the embodiment according to the drawing of figure 1 in its upper area, an operating panel 8 extending in the transverse direction QR is assigned, which can include an access opening 7 accessible from the front for manually opening and/or closing the door 3 .

Dishwasher 1 also has an inlet opening opening into washing compartment 2, in particular exhaust opening 9, via which air for drying items to be washed can be introduced into the washing compartment during at least one drying phase within a program sequence. Also several entry openings, in particular Exhaust openings 9 could alternatively be possible. Here the blow-out opening 9 protrudes into the interior of the washing compartment 2 at the rear right-hand corner of the bottom of the washing compartment 2--seen from the front side VS. Alternatively, the exhaust opening can also be provided in the door.

In a first embodiment of the invention, the blow-out opening 9 is designed to be unchangeable, in particular rigid, and therefore requires no adjusting elements for its movement.

Furthermore, in the present exemplary embodiment, the dishwasher is provided with a sorption drying device 12, which figure 12 is drawn. Air that has passed through the sorption drying device 12 can be introduced into the washing container 2 during a phase drying the items to be washed or a drying cycle of the washing cycle of a dishwashing program that is currently running. The sorption drying device 12 is preferably a component of an air circulation system. This includes an air duct 24 which connects an air outlet opening 23 in the washing compartment 2 to the air outlet or blow-out opening 9 in a wall, here for example in the bottom part of the washing compartment 2 . The sorption drying device 12 is inserted into the air duct 24 . Between the air outlet opening 23 and the sorption drying device 12, i.e. viewed in the air flow direction, a fan 17 is inserted in front of the sorption drying device 12, which during drying operation ensures that air laden with moisture is blown out of the interior of the washing compartment through the outlet opening 23 into the air duct 24 is sucked in, is conveyed or transported through the sorption drying device 12, where its sorption material (such as zeolite) removes moisture from the moist air by adsorption, and then the air dried in this way is blown into the interior of the washing compartment via the blow-out opening 9 and thus back into it is supplied. The blown-in air then absorbs moisture from the items to be washed again. Finally, a desired degree of drying of the items to be washed is ensured by the continued circulation of the air from the interior of the washing compartment through the air duct with the sorption drying device.

For the desorption of the sorption material can be considered in the air duct in the air flow direction in front of the sorption drying device and / or in the Sorption drying device may be provided at least one electric heating device. In the present embodiment, the heating device is in the figure 12 marked with HZ. The desorption is preferably carried out during a partial wash cycle with washing liquid to be heated, for example during the cleaning cycle of a subsequent dishwashing program. The blower is activated so that air is sucked out of the interior of the washing compartment through the outlet opening 23 into the air duct 24 and is transported through the sorption drying device 12 . The sorption material and/or the air that is passed through are heated by the electric heating device, so that the air absorbs the moisture adsorbed on the sorption material. The sorption material is thus dried and is available regenerated for adsorption drying for the drying cycle of the rinse cycle of a subsequent dishwashing program.

In order to allow air to be blown into the washing container 2 via the blow-out opening 9 in this version, but also in another embodiment, at least one blower or fan 17 is provided, preferably as a further component of the air duct 24 . During the respective drying phase of a dishwashing program to be carried out, moist air to be dried is sucked from the interior of the washing compartment 2 via the air outlet opening 23 of the washing compartment into the air duct 24, through which it is conducted via the inlet-side section (viewed in the flow direction of the air) to the sorption drying device 12 conveyed through it and the moisture contained in the air is adsorbed by the sorption material. The air dried in this way is then moved via the downstream section of the air duct 24 in the direction of the blow-out opening 9 and is blown back through it into the interior of the washing compartment.

Of course, instead of such an air circulation system with a sorption drying device, the dishwasher can also have another drying system that works according to an alternative or modified drying principle. So-called exhaust air drying can be provided, for example, in which the process air is discharged from the washing container, for example via a process air duct by means of a drying air fan present there, where it is blended or mixed with outside air or ambient air, ie enriched and then blown out of the dishwasher in its vicinity. If necessary, instead of a specially provided process air duct, provision can also be made for the door to be partially opened, so that a ventilation gap is provided for moist air to escape to the outside. Such a discharge of internal air out of the washing container can expediently be supported by a fan. With these variants of exhaust air drying, outside air flows from the environment through an opening in the washing compartment or the door into the interior of the washing compartment. Here, too, there is an inlet opening, in particular a blow-out opening, for the inflow or introduction of air into the interior of the washing compartment.

In a modification of this, in the case of circulating air drying, the process air duct leads the process air, which may have been blended or mixed with outside air, via a blow-out opening back into the rinsing container. Alternatively or additionally, the process air duct and/or its fan can be provided with a condensation surface, so that condensation drying of moist air flowing past is effected there. If necessary, ambient air can be routed past the outside of the condensation surface via a fresh air duct in order to cool it. For this purpose, the fresh air duct can have its own fan or the fan of the process air duct is designed as a common fan for the process air duct and the fresh air duct.

In addition, there are a number of other air drying systems in which air is guided or moved into the interior or treatment room through a blow-out opening such as 9 in a wall of the washing compartment and/or the door - possibly by means of a blower such as 17, for example. If drying is assisted by opening the door a little, the inlet opening can also be formed by this gap under certain circumstances.

In a first exemplary embodiment, the exhaust opening 9 is immovable and has a constant cross section. Versions are described further below that differ in this respect and also change the flow distribution SV in the washing container 2 by mechanical changes to the blow-out opening 9 .

During a wash cycle, the dishwasher runs through different program steps of an ongoing dishwashing program, including at least one Drying phase (several are also possible), in which an air flow 13 is introduced through the blow-out opening 9 to dry the items to be washed in the washing compartment 2 . The respective dishwashing program thus implements one or more liquid-carrying partial wash cycles and at least one drying cycle.

In any case, there is a variation in the local flow distribution SV of the air in the washing compartment in that the volume flow Q that can be introduced into the washing compartment via the blow-out opening 9 and/or the exit speed c of air 13 for drying the items to be washed varies several times over the drying phase TG. In the context of the invention, volume flow is understood in particular to mean the respective volume of air which leaves the opening cross section of the blow-out opening per unit of time, ie within a period of time. If there is an unchanging outlet opening, the relationship Q = c A applies, where A is the opening cross-section of the outlet opening, c is the outlet velocity and Q is the resulting volume flow in liters per second.

Such a drying phase of the wash cycle executed by the respective dishwashing program of a dishwasher preferably lasts at least 15 minutes, in particular typically several 10 minutes, preferably between 30 and 60 minutes. In the illustrations after Figures 3 and 4 a period of 30 minutes is set as an example for the drying phase. The variation or change in the volume flow and/or the exit speed of the air introduced into the washing compartment via the blow-out opening causes the local flow distribution SV of the air in the washing compartment to vary several times during the drying phase. Examples are in the Figures 7 to 10 shown. In other words, different local flow distributions of the air in the interior of the washing compartment result as a function of changes or variations in the volume flow and/or the flow rate at which the air exits from the exhaust opening.

In figure 7 Due to a very high outflow speed c of the air from the exhaust opening 9, a local air flow distribution with a high proportion of cross-flow 14 can be seen in the vicinity of the bottom 16 of the washing compartment, so that the entire lower area of the washing compartment 2 with a large volume flow Q of the drying air is swept over and the vertical flow 15 is distributed over the entire width of the washing compartment 2 .

In figure 8 on the other hand, the outlet speed c of the air emerging from the outlet opening 9 is compared to the local air flow distribution SV figure 7 lower, so that after passing through the sorption material of the sorption drying device 12, the air, which has been dried and thereby heated, flows upwards with a larger proportion of vertical flow 15, and as a result opposite figure 7 deviating areas of the rinsing tank 2 are subjected to more intense air.

According to the local air flow distribution SV of figure 9 there is both a high proportion of cross-flow 14 and a high proportion of vertical flow 15, which is possible, for example, with a high outlet velocity on the one hand and a high air temperature on the other, for example at the beginning of the drying phase (see Fig figure 6 ).

the figures 9 and 10 also show how different air currents can form in the rinsing tank. These images can also be snapshots during a change in volume flow. For example, cutlery drawer 10 and upper crockery basket 11 are acted upon here from a direction of flow from above—unlike in FIGS figures 7 and 8th .

The volume flow and/or the outlet speed of the air introduced from the blow-out opening into the interior of the washing compartment are preferably varied over the duration of the respective drying phase of a wash cycle such that a turbulent air flow is formed in the washing compartment. This increases the probability with which the respective local area in the washing compartment of the washing compartment can be covered or swept over by a sufficient air flow for drying the items to be washed.

It becomes clear how many different and mutually alternating distributions of air flows are possible within a drying phase, so that a wide variety of areas of the interior of the washing compartment 2 times with high and times with lower intensity of the air flow and/or also from different flow directions RI are reached . This change in volume flow Q and/or outlet speed c and/or outflow direction of the air flowing into the washing tub via the exhaust opening, it is also not important whether, for example, large items of washware in the washing tub form obstacles for the air flow, since these obstacles are hit from different directions and are therefore also flown behind.

The described variation in the outlet speed of the air from the outlet opening 9, which is accompanied by a change in the volume flow with a constant outlet cross section, can be effected particularly advantageously via different speeds DR of a fan 17 connected upstream of the outlet opening 9, or at least can be effected with its support.

The variation of the volume flow and/or the exit speed is expediently controlled via a sequence program which is carried out via a preferably electrical control device, in particular a control unit CO (see figure 12 ) the dishwasher 1 stored program is permanently preset. No data from ongoing operation is required for this, but the program can be run without measured input data.

This is according to the Figures 3 and 4 the speed DR of the blower 17, which changes over time t, is variably preset via the program sequence.

As is clear from the curves DV, SV drawn there, the speed of the blower 17 during the drying phase - outside of a start-up and run-down phase of the blower - is in an interval IV between maximum speeds such as DMA (here: 6000 rpm) and Minimum speeds such as DMI (here: 3000 rpm) are maintained, so that there are several 10% variations from the upper to the lower speed limit (here 50%). Generally speaking, the lowest values of the rotational speed DR are more than 5% below the highest values. Here in the exemplary embodiment, the lowest values of the rotational speed DR are in particular more than 1000 revolutions per minute below the highest values and are therefore significantly more than 5% below the highest values. The fluctuations are thus far above the tolerance fluctuations that are usual in control loops for a constant speed.

At the beginning of the drying phase TG, the rotational speed DR is first increased to a maximum rotational speed DMA and then lowered to a minimum rotational speed DMI of interval IV. The high initial speed means that a particularly large amount of water can be transported out of the rinsing tank in this phase. In particular, a sorption drying device such as 12 absorbs a lot of water in this phase and gives off a lot of thermal energy (see Figures 5, 6 ). It is therefore particularly useful to vary the volume flows several times in the initial phase, ie during an initial period of time AP of the drying phase TG, in order to effectively flow around as many areas of the interior of the washing compartment as possible.

figure 5 shows a schematic representation of the water absorption capacity of zeolite as a sorption material as a function of the progression of the drying time t during a drying cycle TG, which here lasts 30 minutes, for example. In this embodiment, after about 5 minutes from the start time (at t = 0 minutes) of the drying cycle TG by sorption drying, about half of the total amount of moisture or water caused by the total amount, here of about 200g, of sorption material in the sorption drying device 12 is adsorbable, bound in the sorption material, here zeolite. Corresponding to figure 5 the figure shows schematically the development over time of the blow-out temperature T in °C of the air that is blown out of the blow-out opening into the washing chamber of the washing compartment during the drying phase TG, as a function of the time t in minutes. During the initial period AP of the sorption process, the air passed through the sorption drying device reaches its highest temperature and then drops by the end of the drying cycle or the drying phase TG, here at around 30 minutes. The first maximum can also be particularly high in order to make drying very effective. Further maxima can then be lowered somewhat in order to reduce the average noise level.

How often this speed interval is run through after the initial time period AP can vary. Since, for example, with a sorption drying device 12, the water drainage is particularly high in the first few minutes (see figure 5 ), it is possible to work mainly at the minimum speed such as DMI of the interval such as IV, for example, and also to consider the noise level and reduce energy demand. In particular, a shorter rapid drying phase is also made possible.

In most cases it is favorable if the rotational speed DR of the blower 17 runs through the interval between maximum and minimum rotational speed such as DMA and DMI at least twice during the drying phase TG. The curves can be different, as in the comparison of the Figures 3 and 4 becomes clear:

According to figure 3 the speed profile DV is variable over at least part of the drying phase TG in the manner of a sine curve between maximum and minimum values. According to figure 4 on the other hand, the speed profile DV is variable over at least part of the drying phase in the manner of a step function between maximum and minimum values. Maximum or minimum speeds can be maintained for several minutes. Mixed forms or other curve characteristics are also possible. For example, a sawtooth curve can be implemented in a particularly simple manner by repeatedly changing between an upper setpoint speed and a lower setpoint speed of the fan. The speed increases essentially linearly between the lower setpoint speed and the upper setpoint speed. In contrast, the speed falls essentially linearly between the upper setpoint speed and the lower setpoint speed.

If a large number of different operating points are passed through, the effect achieved is that all areas of the interior or washing chamber of the washing container are flown around twice more weakly and sometimes more strongly and no dead areas remain in the washing chamber.

In order to reduce the average noise level of the dishwasher over the entire duration of the wash cycle of the respective dishwasher program to be carried out, it can be particularly useful if the fan is controlled in such a way, in particular by the control device CO via a control line 20, that the higher target speed, e.g. DMA of the blower is approached for a shorter period of time than the lower target speed such as DMI.

The speed DR of the fan 17 during the drying phase TG—outside a start-up and run-down phase of the fan—is favorable in a (speed value) interval such as IV between at least one, in particular predeterminable, basal value Maximum speed such as DMA (see e.g figure 3 ) and at least an absolute minimum speed such as DMI, so does not drop to zero, so that the drying time of the drying phase TG is used effectively. In the respective speed value interval, a large number of other speed values can of course be approached and varied as relative speed maximums and minimums. These target speed values are therefore lower than the upper speed limit such as DMA and higher than the lower speed limit DMI of this interval such as IV. The interval can be selected in particular so that the average noise level falls below a set limit value. Due to the independence of the control, the noise level is always the same.

The speed at the beginning of the drying phase is first increased to a maximum speed such as DMA and then reduced to a minimum speed such as DMI of the interval. The amount of water to be discharged at the beginning of the drying phase is particularly high in the case of the sorption devices mentioned above. This can be taken into account by the particularly high rotational speed initially during an initial period of the drying phase or the drying cycle.

The respective selected minimum speed (lowest value) and maximum speed (maximum value) of the speed change range specified for the speed variation is preferably outside the speed range that occurs when the fan is initially started up or stopped. The minimum speed is selected in particular from a speed range other than zero revolutions per minute (=rpm ("rounds per minute")), from which the fan can set a desired operating speed in a defined manner. Tests have shown that for the fan types commonly used in dishwashers for drying, only a rotational speed DR of at least 1500 revolutions per minute is favorable for control engineering reasons. This is because many fans that have a so-called PMSM (permanent magnet synchronous motor) electric motor can only be set, in particular regulated, to a desired speed from 1500 revolutions per minute. A value between 3000 and 4000 revolutions per minute is preferably selected for the first, lower setpoint speed to be set (absolute lowest value of the speed variation interval) (see figure 3 ). A value that is at least 5000 revolutions per minute, is in particular between 5000 and 6000 revolutions per minute (see figure 3 ). The distance between the lower or lower speed and the upper, higher speed is selected in particular to be more than 1000 revolutions per minute. Expressed in general terms, the respective lowest value of the desired speed is expediently more than 5% below the respective highest value of the desired speed and thus clearly above any tolerance fluctuations of a speed-controlled motor. A speed variation between the minimum and maximum values is advantageously chosen in such a way that it falls within a range of auditory perception that users of dishwashers perceive or accept as uncritical.

If, according to an advantageous development of the invention, the speed of the fan runs through the (speed value) interval between maximum and minimum speed at least twice during the drying phase, a large change in the air flow can be brought about, so that a wide variety of local distributions of the (air) flow are realized in the washing compartment are. This means that the speed of the blower changes several times between a first (non-zero) target speed and a different, second (non-zero) target speed during the duration of the drying phase, i.e. is varied.

In particular, with the blower 2-10 changing between a preferably predeterminable lower target speed such as DMA and a preferably predeterminable upper target speed such as DMI over the entire duration of the drying phase TG of the respective wash cycle can be expedient in order to improve the drying performance the dishwasher to bring about a sufficient change or variation in the local air flow distribution SV in the interior of the washing compartment. The period of time for the change between the first target speed and the second target speed, which differs therefrom, is expediently at least 30 seconds, in particular between 1 minute and 5 minutes.

In addition to the changes shown in the volume flow when the discharge opening 9 is not mechanically influenced, its cross section and/or exit direction can also be influenced in phases via actuators. For example, an actuator can cause the blow-out opening 9 to pivot about its vertical axis 18 .

In addition or as an alternative, the variation of the volume flow can be effected (in part) via at least one controllable closure element 19 assigned to the blow-out opening 9 . This is in figure 11 arranged and can completely or partially interrupt the air flow leading to the exhaust opening 9 . The switching, in particular the switching on and off, of this closure element 19 can vary periodically or otherwise and is in figure 11 indicated as a diagram over time t. A control line 20 leads from the control device CO, in particular the control unit, with the program storage to the closure member 19.

Instead of the valve, a sector disc (not shown) rotating in the air flow with open and closed areas can also be provided as the closure member 19, which rotates continuously and thereby alternately blocks or releases the air flow (partially). The open areas can, for example, be of different sizes over the circumference. Strict periodicity is therefore not necessary here either, but the opening and closing times can vary over the drying time.

If necessary, the volume flow and/or the exit speed of the air introduced through the exhaust opening into the interior of the washing compartment can be varied simply by a rotatable disc or other closure element that has only a single opening and is otherwise closed. Depending on whether this one opening is completely aligned with the exhaust opening, is only partially aligned with the exhaust opening and/or the closed area or the covering zone of the closure element completely covers and thus closes the exhaust opening, and in which temporal Depending on the sequence and duration of the opening, partial closing and/or complete closing of the exhaust opening, changing local air flow distributions occur over the duration of the drying phase in the interior of the washing compartment.

The driving force of the closure member 19 can be effected via its own actuators. It is also possible to tap off a motor for the fan 17, for example via a reduction gear.

At least one movable mechanical control means, such as an air baffle, a nozzle with variable direction, a movable flap or the like, can also be assigned to the exhaust opening 9, so that the outlet cross section (and thus the outlet speed of the air) and/or the outlet direction AR over time the drying phase varies. This can also alternate between extreme positions, so that curves similar to those in FIGS Figures 3 and 4 can arise.

In addition, for example flaps or the like can also be controlled by the varying air flow itself, so that they align themselves due to the different volume flows.

In figure 12 such a supplementary embodiment is shown, in which a control line 20 controls the blower speed and a further control line 20 is provided for influencing the exhaust opening 9 . In addition, a third control line 20 can also be used to influence a switching element 22 at the air outlet from the washing container 2, i.e. in the area of the air outlet opening 23 of the washing container and/or the suction opening of the air duct 24, in order to temporarily prevent air from accumulating there by closing it to generate an overpressure and temporarily a free passage.

At point 21 in the rinsing container, an example of how flow vectors can vary there in terms of amount, in particular with regard to the volume flow value and/or the flow rate, and direction RI over the drying period is illustrated.

The invention therefore results in both improved drying with the same energy input and independent drying from the respective load.

The solution is particularly customer-oriented and, due to the speed reductions with different operating points of the blower 17, offers reduced noise pollution without loss of effectiveness.

Reference list:

1

Dishwasher,

2

processing tank,

3

Door,

4

pan direction,

5

body,

6

decorative panel,

7

access opening,

8th

control panel,

9

exhaust port,

10

cutlery drawer,

11

dish rack,

12

sorption drying device,

13

airflow,

14

cross flow component,

15

vertical current fraction,

16

bottom of the rinsing tank,

17

Fan,

18

vertical axis,

19

fastener link,

20

control line,

21

point in the flush tank,

22

switching element,

23

air outlet opening,

24

air duct,

AR

exit direction,

DR

Rotation speed,

dv

RPM curve as a function of time,

HZ

heating device,

RI

flow direction,

SV

local air distribution or flow distribution,

Q

Volume flow or air throughput,

c

exit velocity,

CO

Control device, in particular control unit,

vs

Front,

QR

transverse direction

Claims (17)

1. Dishwasher (1), in particular a household dishwasher, with a wash container (2) for cleaning dishes, glasses, cutlery or similar items to be washed, wherein it is possible for air to be introduced into the wash container (2) by way of at least one inlet opening, in particular a discharge opening (9), during at least one drying phase (TG) or another process phase within a program sequence, wherein the volume flow (Q) of air (13) that can be introduced into the wash container (2) through the inlet opening, in particular discharge opening (9), varies a number of times over the drying phase (TG) or the other process phase, or the exit speed (c) of the air that can be introduced into the wash container (2) varies a number of times at the discharge opening (9) over the drying phase (TG) or another process phase, wherein the volume flow (Q) and/or exit speed (c) can (also) be varied by way of different rotation speeds (DR) of a blower (17) positioned before the discharge opening (9) and the rotation speed (DR) of the blower (17) is kept in an interval (IV) between at least one, in particular predefinable, maximum rotation speed (DMA) and at least one, in particular predefinable, minimum rotation speed (DMI) during the drying phase (TG) or another process phase - apart from a start-up and run-down phase of the blower, wherein the respective lowest value (DMI) of the rotation speed (DR) is more than 5% below the respective highest value (DMA) of the rotation speed, and wherein the rotation speed (DR) is first raised to the maximum rotation speed (DMA) at the start of the drying phase (TG) or another process phase and is then reduced to the minimum rotation speed (DMI) of the interval (IV).
2. Dishwasher (1) according to claim 1,
   characterised in that
   varying the volume flow (Q) and/or exit speed (c) varies the local flow distribution (SV) of the air in the wash container (2) a number of times during the drying phase (TG) or another process phase.
3. Dishwasher (1) according to one of claims 1 or 2,
   characterised in that
   the variation of volume flow (Q) and/or exit speed (c) is/are controlled by way of a sequence program.
4. Dishwasher (1) according to claim 3,
   characterised in that
   the variation is preset in a fixed manner by way of a program stored in a control unit (CO) of the dishwasher (1).
5. Dishwasher (1) according to claim 4,
   characterised in that
   the program can be performed without measured input data.
6. Dishwasher (1) according to one of claims 1 to 5,
   characterised in that
   the dishwasher is provided with a sorption drying facility (12).
7. Dishwasher (1) according to claim 6,
   characterised in that
   during the drying phase air, which has passed through the sorption drying facility (12), can be introduced into the wash container (2).
8. Dishwasher (1) according to one of claims 1 to 7,
   characterised in that
   the rotation speed (DR) of the blower (17) is preset in a variable manner over the program sequence.
9. Dishwasher (1) according to one of claims 1 to 8,
   characterised in that
   the rotation speed (DR) of the blower (17) passes at least twice through the interval (IV) between maximum and minimum rotation speed over the drying phase (TG) or another process phase.
10. Dishwasher (1) according to one of claims 1 to 9,
    characterised in that
    the rotation speed profile (DV) can vary in the manner of a sawtooth or sine profile between one or more highest and lowest values (DMA, DMI) over at least a sub-segment of the drying phase (TG) or another process phase.
11. Dishwasher (1) according to one of claims 1 to 10,
    characterised in that
    the rotation speed profile (DV) can vary in the manner of a step function between one or more highest and lowest values over at least part of the drying phase (TG) or another process phase.
12. Dishwasher (1) according to one of the preceding claims,
    characterised in that
    the volume flow (Q) and/or exit speed (c) can (also) be varied by way of at least one activatable closing element (19) assigned to the inlet opening, in particular discharge opening (9).
13. Dishwasher (1) according to claim 12,
    characterised in that
    the closing element (19) comprises a sector disk that rotates in the air flow with just one open region and a closed region or with a number of open and closed regions.
14. Dishwasher (1) according to claim 13,
    characterised in that
    the open regions extend to different lengths over the periphery.
15. Dishwasher (1) according to one of the preceding claims,
    characterised in that
    at least one movable, mechanical control means, for example a baffle, a variable-direction nozzle, a movable flap or the like, is assigned to the inlet opening, in particular discharge opening (9).
16. Dishwasher (1) according to claim 15,
    characterised in that
    the exit direction (AR) of the air flow into the wash container (2) can be influenced by the at least one control means.
17. Dishwasher (1) according to one of the preceding claims,
    characterised in that
    the other process phase is the desorption phase for a sorption drying facility (12).

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