EP3777637B1 - Dishwasher, in particular a domestic dishwasher - Google Patents

Description

The invention relates to a dishwasher, in particular a domestic dishwasher, with a washing compartment providing a washing area which is used to hold items to be cleaned, and with a fresh water tank, the fresh water tank being fluidically connected to the washing compartment.

Dishwashers in general and those of the generic type are well known per se from the state of the art, which is why separate printed evidence is basically not required at this point.

Previously known dishwashers have a washing container that provides a washing area. This is accessible on the user side via a loading opening which can be closed in a fluid-tight manner by means of a pivotably mounted wash cabinet door. When used as intended, the washing container serves to hold items to be cleaned, which can be, for example, dishes, cutlery and / or the like.

The dishwasher has a spray device in the interior of the washing compartment for the application of washing liquid, the so-called washing liquor, to items to be cleaned. This spray device typically provides rotatably mounted spray arms, two or three such spray arms being provided as a rule. When used as intended, the items to be cleaned are exposed to washing liquor by means of rotating spray arms.

The wash liquor released by a spray device during operation hits the wash ware to be cleaned and then collects in a collecting pot of the wash container. The collecting pot is connected to a circulation pump on the one hand and a drain or waste water pump on the other hand. The circulating pump, which, when used as intended, circulates the washing liquid conveyed into the dishwasher is used to apply washing solution to the spray device. At the end of a wash program, the wash liquor is pumped out by means of the drain pump and discarded.

At the start of a washing program, fresh water is supplied to the washing container, which is typically taken from the public fresh water network. After the washing compartment has been filled with fresh water, the actual washing program begins and the circulating pump is started to charge the spray device.

During a wash program, different program sections are run through, for example a pre-wash program, a cleaning program, an intermediate wash program, a final-rinse program and / or the like. After the wash program has ended, a drying program is typically provided. In particular, the washing solution is heated up during a cleaning program and during a final rinse program. For this purpose, appropriate heating devices are used which, depending on the initial temperature of the fresh water, require a correspondingly large amount of energy until the target temperature of the washing solution for the respective washing program section is reached. The heating energy required is greater, the greater the difference between the initial temperature of the fresh water and the target temperature desired for carrying out a wash program section.

In this context, a fresh water tank is known from the prior art, which is arranged on the outside of the washing compartment. This fresh water tank is fluidically connected on the one hand to a fresh water line and on the other hand to the washing container. After a properly running wash program has ended, the fresh water tank is filled with fresh water from the fresh water line. This remains in the fresh water tank until the next wash program is carried out and is stored by this. This has the advantage that the fresh water can warm up from typically 17 ° C to room temperature of e.g. 23 °. The next upcoming wash program is then carried out at least partially with fresh water preheated to room temperature, so that the temperature difference between the initial temperature of the fresh water introduced into the wash container and the target temperature to be achieved for carrying out a wash program section is reduced, with the result that less heating energy is required.

From the prior art it is according to DE 10 2013 213 970 B4 also known, the sewer connected to the drain or sewage pump through the Pass through the fresh water tank. This has the positive effect that during a wash program section, heated wash liquor that is now to be discarded by means of the waste water pump is passed through the fresh water tank, as a result of which there is a transfer of heat from the still comparatively warm and discarded wash liquor to the cooler fresh water stored in the fresh water tank.

Although the measures described above have proven themselves in everyday practical use, there is still room for improvement. In particular, the aim is to propose a heat recovery system that contributes more effectively to being able to save heating energy by extracting heat from used washing liquor to heat up fresh water. It is therefore the object of the invention to propose a dishwasher of the type mentioned at the outset with a heat recovery system which makes it possible to an increased extent to minimize the heating energy required to carry out a washing program through heat transfer.

To solve this problem, the invention proposes a dishwasher of the type mentioned at the outset, which is characterized by a second fresh water tank and a heat exchanger, the second fresh water tank being connected to the first fresh water tank by means of a first pipeline on the one hand and by means of a second pipeline with the interposition of the heat exchanger on the other is fluidically connected.

The dishwasher according to the invention has a first fresh water tank on the one hand and a second fresh water tank on the other hand. In addition to the fresh water tank known from the prior art, a second fresh water tank is therefore provided.

The dishwasher according to the invention also has a heat exchanger.

The first fresh water tank and the second fresh water tank are fluidically connected. Two pipelines are provided for this purpose, namely a first pipeline on the one hand and a second pipeline on the other. The heat exchanger is integrated into the second pipeline, which means that the second fresh water tank is fluidically connected to the first fresh water tank by means of the second pipeline with the interposition of the heat exchanger.

The advantage of the second fresh water tank, which is separate from the first fresh water tank, is first of all that an overall larger volume of fresh water can be stored so that, in contrast to the prior art, more fresh water is available that can be warmed up to room temperature before the start of a wash program can.

A further advantage is that a targeted transfer of heat from a previously heated wash liquor to fresh water from the second fresh water tank can take place by means of the heat exchanger, so that this fresh water can be brought to an even higher temperature level. However, before this warmed up fresh water can be introduced into the washing container, the washing container must first be completely emptied so that the fresh water is not contaminated with still soiled washing liquor. In this respect, the preheated fresh water needs to be temporarily stored, for which purpose the first fresh water tank is used. In a synergetic way, the two fresh water tanks provided not only increase the total available tank volume, but also create an intermediate storage option, which allows fresh water previously warmed up to room temperature to be brought to an even higher temperature level in the heat exchanger and thus heated To be able to temporarily store fresh water until it can be introduced into the washing compartment after it has been emptied beforehand.

The embodiment according to the invention allows a process to be carried out for a wash program which comprises at least one cleaning program as wash program sections and a final rinse program at the end of the wash program, as follows:
After a properly completed washing program has ended, both the first fresh water tank and the second fresh water tank are filled with fresh water. The fresh water stored in this way can warm to room temperature until the next wash program is carried out.

When a subsequent wash program is carried out, the fresh water stored in the first fresh water tank can, for example, be introduced into the wash container at the start of a cleaning program. This is then heated to the target temperature and the cleaning program is carried out. During this, the fresh water stored by the second fresh water tank remains in the second fresh water tank.

After the cleaning program has ended, the washing liquor that is no longer required is pumped out and discarded. In doing so, it is passed through the heat exchanger. Fresh water coming from the second fresh water tank is fed in countercurrent through the heat exchanger. In the heat exchanger, there is a transfer of heat from the washing liquor to the fresh water coming from the second fresh water tank. This leads to an increase in the fresh water temperature.

The fresh water warmed up in the heat exchanger reaches the first fresh water tank from the second fresh water tank with the interposition of the heat transfer. There the fresh water is stored until a rinse program is carried out.

Subsequent to a cleaning program, there is typically an intermediate rinse in order to completely remove the washing liquor from the dishwasher that has been contaminated after a cleaning program. As soon as such an intermediate wash cycle is completed, the fresh water in the first fresh water tank and originally coming from the second fresh water tank is passed into the washing compartment so that the final rinse program can now be carried out.

It is particularly preferred to dimension the size of the second fresh water tank in such a way that enough fresh water can be stored that the intermediate rinsing that takes place before a final rinse program can also be carried out with fresh water from the second fresh water tank.

In this case it is provided that the second fresh water tank is not completely emptied if fresh water is transferred from it to the first fresh water tank with the interposition of the heat transfer. The remaining amount of fresh water in the second fresh water tank can then be used for an intermediate rinse. The advantage here is that the intermediate rinse with Fresh water is carried out to room temperature, so that individual dishwasher components do not cool down unnecessarily before a final rinse is initiated. In this way it is ensured that the temperature difference between the starting temperature of the fresh water introduced into the washing compartment and the target temperature to be achieved desirably to carry out the final-rinse program is minimized, which leads to a minimization of the heating energy required.

According to a further feature of the invention, it is provided that the first fresh water tank has an overflow to which the first pipeline is connected. When the first fresh water tank is filled with fresh water from the fresh water line, the second fresh water tank is also automatically filled with fresh water when a level inside the fresh water tank is reached above the overflow. A second fresh water line for the second fresh water tank and / or a pump is therefore not required.

According to a further feature of the invention, it is provided that the second fresh water tank is fluidically connected to the washing container by means of a third pipeline. This third pipeline allows fresh water from the second fresh water tank to be fed directly into the washing compartment. In this way, fresh water can optionally be charged from the second fresh water tank either to the washing compartment via the third pipeline or to the first fresh water tank by means of the second pipeline with the interposition of the heat exchanger. The third pipeline serves in particular to transfer fresh water from the second fresh water tank into the washing container during an intermediate washing step.

According to a further feature of the invention, it is provided that the third pipeline branches off from the second pipeline with the interposition of a switchover valve, the switchover valve being connected upstream of the heat exchanger in terms of flow. In this way, a simplified pipe or line system is provided. The third pipeline branches off from the second pipeline, it being possible to set by means of a switching valve whether the third pipeline is to be charged with fresh water or not. If the third pipeline is not fed with fresh water, this is carried out solely through the second pipeline with the interposition of the heat exchanger.

It should be noted that a pipeline within the meaning of the invention, in particular as a first, second and third pipeline, is to be understood as any type of fluid line that ensures operationally reliable liquid transport within the dishwasher. The pipelines or partial sections of the pipelines can be made fixed, in particular made of plastic or metal, or also elastic, that is to say, for example, as a hose.

According to a further feature of the invention, it is provided that the heat exchanger is fluidically connected to a waste water line opening into the washing container at the other end. Rinsing liquor originating from the rinsing container is led through this waste water line when used as intended. This is preferably conveyed by means of a pump provided for this purpose from the collecting pot of the washing container, passed through the heat exchanger and into the waste water line, whereby the used washing liquor is discarded. Fresh water from the second fresh water tank is conducted in countercurrent through the heat exchanger, so that heat from the washing liquor from the washing compartment can be transferred to the fresh water from the second fresh water tank.

According to a further feature of the invention, the heat exchanger is a coaxial heat exchanger. The heat exchanger preferably has an inner tube made of stainless steel and an outer tube made of plastic that accommodates the inner tube while leaving an annular gap. The inner tube is preferably made of stainless steel in order to enable an optimized heat transfer between the washing solution and fresh water. The outer tube is made of plastic in order to provide thermal insulation so that heat is not unnecessarily lost to the outside atmosphere surrounding the heat exchanger. For an optimized heat transfer, the heated rinsing solution is passed through the stainless steel pipe, whereas the fresh water to be heated is passed through the annular gap between the inner pipe and the outer pipe.

According to a further feature of the invention it is provided that the first fresh water tank is arranged as a side tank next to the washing container. Accordingly, the first fresh water tank is arranged on an outside, in particular a side wall or the rear wall of the washing compartment. An insulation is preferably formed between the first fresh water tank and the washing container.

The second fresh water tank is preferably designed as a base tank below the washing compartment. This makes it possible to optimally utilize the installation space made available by a dishwasher. A lateral design of the second fresh water tank is also possible, but for the preferred size of approx. 4 l tank volume, the arrangement in the base area is preferred.

• bei dem der erste Frischwassertank zur Befüllung von erstem und zweitem Frischwassertank mit Frischwasser beaufschlag wird,
• bei dem zu Beginn eines Reinigungsprogramms im ersten Frischwassertank befindliches Frischwasser in den Spülbehälter geleitet wird,
• bei dem mit Beendigung des Reinigungsprogramms die im Spülbehälter befindliche Spülflotte abgepumpt und verworfen wird,
• wobei die Spülflotte im Gegenstrom mit aus dem zweiten Frischwassertank stammendem Frischwasser durch den Wärmeübertrager geführt wird
• und wobei das aus dem zweiten Frischwassertank stammende Wasser nach einem Passieren des Wärmeübertragers in den ersten Frischwassertank geführt und dort bevorratet wird und
• bei dem mit Beginn eines Klarspülprogramms das sich im ersten Frischwassertank befindliche Frischwasser in den Spülraum geführt wird.

The invention also proposes, on the process side, a method for operating a dishwasher of the type according to the invention,

• in which the first fresh water tank is charged with fresh water to fill the first and second fresh water tanks,
• in which fresh water in the first fresh water tank at the start of a cleaning program is fed into the rinsing container,
• in which when the cleaning program ends, the washing solution in the washing compartment is pumped out and discarded,
• wherein the rinsing liquor is passed through the heat exchanger in countercurrent with fresh water coming from the second fresh water tank
• and wherein the water originating from the second fresh water tank, after passing through the heat exchanger, is fed into the first fresh water tank and stored there, and
• in which the fresh water in the first fresh water tank is fed into the wash cabinet at the start of a final rinse program.

With the method according to the invention, the advantages already described above with reference to the dishwasher are achieved.

• dass vor dem Klarspülprogramm ein Zwischenspülprogramm durchgeführt wird, wobei mit Beginn des Zwischenspülprogramms Frischwasser aus dem zweiten Frischwassertank in den Spülraum überführt wird.

According to an advantageous development of the method according to the invention, provision is made

• that an intermediate rinse program is carried out before the final rinse program, with the start of the intermediate wash program, fresh water is transferred from the second fresh water tank into the wash cabinet.

According to this process addition, an intermediate wash program upstream of the final rinse program is also carried out with fresh water preheated to at least room temperature. This prevents the items to be washed and individual dishwasher components from cooling down, as would be the case if an intermediate wash program were carried out with colder fresh water.

Fig. 1

in schematischer Darstellung eine erfindungsgemäße Geschirrspülmaschine;

Fig. 2

in schematischer Seitenansicht einen Wärmeübertrager nach der Erfindung;

Fig. 3

den Wärmeübertrager nach Fig. 2 in einer geschnittenen Querschnittsdarstellung;

Fig. 4

in einer Ausschnittsdarstellung die Geschirrspülmaschine nach Fig. 1;

Fig. 5

in einer schematischen Darstellung eine zur Ausführungsform nach Fig. 4 alternative Ausgestaltung;

Fig. 6

in schematischer Darstellung den Anschluss des zweiten Frischwassertanks an den Wärmeübertrager;

Fig. 7

in schematischer Darstellung ausschnittsweise die Geschirrspülmaschine nach Fig. 1;

Fig. 8

in schematischer Darstellung ausschnittsweise die Geschirrspülmaschine nach Fig. 1;

Fig. 9

in einer schematischen Darstellung eine alternative Ausführungsform zur Ausgestaltung nach Fig. 8;

Fig. 10

in einer schematischen Darstellung eine alternative Ausführungsform zur Ausgestaltung nach Fig. 8;

Fig. 11

in schematischer Darstellung ausschnittsweise die Geschirrspülmaschine nach Fig. 1;

Fig. 12

in schematischer Darstellung eine zur Ausführungsform nach Fig. 11 alternative Ausgestaltung;

Fig. 13

in schematischer Darstellung eine zur Ausführungsform nach Fig. 11 alternative Ausgestaltung;

Fig. 14

in schematischer Darstellung eine zur Ausführungsform nach Fig. 11 alternative Ausgestaltung;

Fig. 15

in schematischer Darstellung den strömungstechnischen Anschluss des Wärmeübertragers an eine Abwasserleitung;

Fig. 16

in schematischer Darstellung ausschnittsweise die Geschirrspülmaschine nach Fig. 1;

Fig. 17

in schematischer Darstellung eine zur Ausführungsform nach den Figuren 15 und 16 alternative Ausführungsform;

Fig. 18

in schematischer Darstellung eine zur Ausführungsform nach den Figuren 15 und 16 alternative Ausführungsform;

Fig. 19

in schematischer Seitenansicht ein Wärmeübertrager nach der Erfindung gemäß einer ersten Ausführungsform;

Fig. 20

in schematischer Seitenansicht ein Wärmeübertrager nach der Erfindung gemäß einer zweiten Ausführungsform;

Fig. 21

in schematischer Seitenansicht ein Wärmeübertrager nach der Erfindung gemäß einer dritten Ausführungsform;

Fig. 22

in schematischer Seitenansicht ein Wärmeübertrager nach der Erfindung gemäß einer vierten Ausführungsform;

Fig. 23

in schematischer Seitenansicht ein Wärmeübertrager nach der Erfindung gemäß einer fünften Ausführungsform;

Fig. 24

in schematischer Seitenansicht ein Wärmeübertrager nach der Erfindung gemäß einer sechsten Ausführungsform;

Fig. 25

in schematischer Seitenansicht ein Wärmeübertrager nach der Erfindung gemäß einer siebten Ausführungsform;

Fig. 26

in schematischer Seitenansicht ein Wärmeübertrager nach der Erfindung gemäß einer achten Ausführungsform;

Fig. 27

in schematischer Darstellung die erfindungsgemäße Geschirrspülmaschine gemäß einer weiteren Ausführungsform;

Fig. 28

in einem Flussdiagramm eine erfindungsgemäße Verfahrensabwicklung;

Fig. 29

in einer schematisch perspektivischen Darstellung den zweiten Frischwassertank gemäß der Ausführungsform nach Fig. 18;

Fig. 30

in einer schematischen Detailansicht den zweiten Frischwassertank in einer alternativen Ausführungsform;

Fig. 31

in einer schematischen Detailansicht den zweiten Frischwassertank in einer alternativen Ausführungsform; und

Fig. 32

in schematischer Darstellung eine Geschirrspülmaschine nach dem Stand der Technik.

Further features and advantages of the invention emerge from the following description with reference to the figures. Show:

Fig. 1

a schematic representation of a dishwasher according to the invention;

Fig. 2

a schematic side view of a heat exchanger according to the invention;

Fig. 3

the heat exchanger Fig. 2 in a cut cross-sectional view;

Fig. 4

in a detail view of the dishwasher Fig. 1 ;

Fig. 5

in a schematic representation one for the embodiment according to Fig. 4 alternative design;

Fig. 6

a schematic representation of the connection of the second fresh water tank to the heat exchanger;

Fig. 7

in a schematic illustration of a section of the dishwasher according to Fig. 1 ;

Fig. 8

in a schematic illustration of a section of the dishwasher according to Fig. 1 ;

Fig. 9

in a schematic representation an alternative embodiment to the configuration according to Fig. 8 ;

Fig. 10

in a schematic representation an alternative embodiment to the configuration according to Fig. 8 ;

Fig. 11

in a schematic illustration of a section of the dishwasher according to Fig. 1 ;

Fig. 12

in a schematic representation one for the embodiment according to Fig. 11 alternative design;

Fig. 13

in a schematic representation one for the embodiment according to Fig. 11 alternative design;

Fig. 14

in a schematic representation one for the embodiment according to Fig. 11 alternative design;

Fig. 15

a schematic representation of the fluidic connection of the heat exchanger to a sewer pipe;

Fig. 16

in a schematic illustration of a section of the dishwasher according to Fig. 1 ;

Fig. 17

in a schematic representation one for the embodiment according to the Figures 15 and 16 alternative embodiment;

Fig. 18

in a schematic representation one for the embodiment according to the Figures 15 and 16 alternative embodiment;

Fig. 19

a schematic side view of a heat exchanger according to the invention according to a first embodiment;

Fig. 20

a schematic side view of a heat exchanger according to the invention according to a second embodiment;

Fig. 21

a schematic side view of a heat exchanger according to the invention according to a third embodiment;

Fig. 22

a schematic side view of a heat exchanger according to the invention according to a fourth embodiment;

Fig. 23

a schematic side view of a heat exchanger according to the invention according to a fifth embodiment;

Fig. 24

a schematic side view of a heat exchanger according to the invention according to a sixth embodiment;

Fig. 25

a schematic side view of a heat exchanger according to the invention according to a seventh embodiment;

Fig. 26

a schematic side view of a heat exchanger according to the invention according to an eighth embodiment;

Fig. 27

in a schematic representation the dishwasher according to the invention according to a further embodiment;

Fig. 28

in a flowchart a method implementation according to the invention;

Fig. 29

in a schematic perspective illustration the second fresh water tank according to the embodiment according to FIG Fig. 18 ;

Fig. 30

in a schematic detailed view the second fresh water tank in an alternative embodiment;

Fig. 31

in a schematic detailed view the second fresh water tank in an alternative embodiment; and

Fig. 32

a schematic representation of a dishwasher according to the prior art.

Fig. 32 shows, in a purely schematic representation, a dishwasher 1 according to the prior art. The dishwasher 1 has a housing (not shown in greater detail in the figures) which, among other things, accommodates a washing container 2. Of the The washing compartment 2, for its part, provides a washing compartment 3 which, when used as intended, is used to hold items to be cleaned.

A spray device 4, which is arranged inside the washing compartment 2, is used to load items to be cleaned with washing liquor. Such a spray device 4 preferably has spray arms 5 which are each rotatably arranged within the washing compartment 2. According to the embodiment according to Fig. 32 the spray device 4 has a total of three spray arms 5.

The washing chamber 3 opens into a collecting pot 6 of the washing container 2, to which a circulating pump 7 is fluidically connected. Via corresponding supply lines 9, 10 and 11, the spray arms 5 of the spray device 4 are fluidically connected to the circulating pump 7, with the interposition of a water switch 8. In the intended use, the spray device 4 can thus be charged with rinsing solution by means of the circulating pump 7, with each after setting the water switch 8, one of the spray arms 5 can be charged with washing liquor.

Furthermore, a waste water pump 12 is fluidically connected to the collecting pot 6, which pumps off washing liquor located in the collecting vessel 6 if necessary and feeds it to the waste water line 13, as a result of which the washing liquor is discarded.

The dishwasher 1 is also connected to a fresh water line 14. Typically, the fresh water line 14 is preceded by a water softener, which is not shown in more detail in the figures. The fresh water line 14 opens into a switchover valve 15. A feed line 16 and a tank line 18 are provided on the output side of the switchover valve 15. In this way, depending on the position of the switching valve 15, either the supply line 16 or the tank line 18 can be served with fresh water.

For reasons of water safety, the supply line 16 typically has a free outlet, which is connected directly downstream of the switching valve 15 in terms of flow. Like the water softener, this free outlet is not shown any further for the sake of clarity. The feed line 16 opens into the collecting pot 6. When the dishwasher is being charged with fresh water, it flows through the supply line 16 consequently fresh water via the fresh water line 14, the switching valve 15 and the supply line 16 directly into the collecting pot 6.

The tank line 18 opens into a fresh water tank 17. This is typically arranged next to the washing container 2 and attached as a side tank to a side wall of the washing container 2.

The fresh water tank 17 is in fluidic communication with the supply line 16, specifically by means of a pipeline 22. This is fluidically connected to the fresh water tank 17 with the interposition of a shut-off valve 21.

If the shut-off valve 21 is in the shut-off position, as in Fig. 32 shown, the pipeline 22 is closed. According to this position of the shut-off valve 21, no fresh water stored by the fresh water tank 17 can flow through the pipeline 22 into the supply line 16. When the shut-off valve 21 is open, fresh water stored in the fresh water tank 17 passes through the pipeline 22 and the supply line 16 into the collecting pot 6.

The fresh water tank 17 is also in fluidic communication with the washing space 3 provided by the washing compartment 2. For this purpose, the fresh water tank 17 has an overflow 19, which is connected to an overflow line 20 which opens into the washing space 3. If the fresh water tank 17 is possibly overfilled with fresh water, the latter reaches the washing area 3 via the overflow 19 and the overflow line 20.

The fresh water tank 17 is used to be filled with fresh water after completion of a properly running wash program. The fresh water stored by the fresh water tank 17 can warm up to room temperature until the next wash program is carried out, so that the heating energy required in the subsequent wash program to heat the wash liquor is advantageously reduced.

Fig. 1 shows a schematic representation of a dishwasher 1 designed according to the invention, which in comparison to the prior art according to Fig. 32 The same structural components of the dishwasher 1 have the same reference numerals.

The dishwasher 1 according to the invention is characterized by a second fresh water tank 23 and a heat exchanger 27. The second fresh water tank 23 is fluidically connected to the first fresh water tank 17 by means of a first pipe 25 on the one hand and by means of a second pipe 31 with the interposition of the heat exchanger 27 on the other hand.

According to the invention, in addition to the first fresh water tank 17, a second fresh water tank 23 is provided, which is preferably designed as a base container, i.e. is arranged in the base area of the dishwasher below the washing container 2.

The first fresh water tank 17 and the second fresh water tank 23 are in flow communication, specifically by means of a first pipe 25. This is connected on the part of the first fresh water tank 17 to an overflow 24 provided by the first fresh water tank 17. This overflow 24 is arranged in the height direction below the overflow 19 of the overflow line 20.

The second fresh water tank 23 is also connected to a ventilation line 26 which opens into the overflow line 20 between the first fresh water tank 17 and the washing container 2.

The second fresh water tank 23 is also in fluidic communication with the first fresh water tank 17 by means of a second pipeline 31, the pipeline 31, the fresh water tank 23 with a pump 32, the pump 32 with a switchover valve 38, the switchover valve 38 with the heat exchanger 27 and the heat exchanger 27 connects fluidically to the first fresh water tank 17.

Furthermore, a third pipe 35 is connected to the switchover valve 38 and opens into the collecting pot 6 on the other end. Depending on the position of the switchover valve 38, fresh water is fed either to the pipeline 31 or to the pipeline 35, starting from the fresh water tank 23.

In terms of flow, the heat exchanger 27 is also connected to the collecting pot 6, specifically by means of a pipeline 34 with a heat exchanger pump 33 interposed Sewer line 13 a. In the intended use case, washing liquor can therefore be conveyed from the collecting pot 6 by means of the heat exchanger pump 33, passed through the heat exchanger 27 and then conveyed to the sewer line 13.

The heat exchanger 27 is, in particular, a synopsis of the Figures 2 and 3 can be seen, designed as a coaxial heat exchanger. It has an inner tube 28 and an outer tube 29 which accommodates the inner tube 28 leaving an annular gap 30. The inner tube 28 is preferably formed from a thin-walled stainless steel tube, whereas the outer tube 29 is formed from a plastic tube.

In the intended use case, fresh water originating from the second fresh water tank 23 can be moved by means of the pump 32 in accordance with the arrows 36 Fig. 2 be guided through the annular gap 30. In countercurrent to this, in correspondence with the arrows 37, washing liquor is guided from the collecting pot 6 through the inner pipe 28 by means of the heat exchanger pump 33, which after passing through the heat exchanger 27 reaches the sewer line 13.

The two fresh water tanks 17 and 23 serve to store fresh water, the fresh water stored by these tanks being introduced into the washing compartment 2 at different times in a washing program carried out as intended.

First of all, the two fresh water tanks 17 and 23 are filled with fresh water, to be precise after the end of a washing program carried out as intended. This filling takes place via the fresh water line 14, the switching valve 15 and the tank line 18. The fresh water tank 17 has the overflow 24 below the overflow 19, to which the first pipeline 25 connects. The fresh water tank 23 can thus be filled by targeted overfilling of the fresh water tank 17. It is important to ensure that the overflow 24 has a sufficiently large cross-section so that the fresh water supplied can flow into the second fresh water tank 23 faster than the water level in the first fresh water tank 17 rises to the higher overflow 19 in the washing area 3. Adequate tank ventilation must be ensured so that the second fresh water tank 23 located below can also be filled. For this purpose a vent line 26 is provided, which goes back into the first The fresh water tank 17 leads directly into the overflow line 20. This ensures that if the fresh water tank 23 is overfilled due to a fault, the excess fresh water can be discharged directly into the washing area 3 via the watertight vent line 26.

For further use of the fresh water stored by the second fresh water tank 23, it must be pumped up from the fresh water tank 23 arranged below the washing compartment 2. The pump 32 is provided for this, which pumps the fresh water from the fresh water tank 23 through the heat exchanger 27. A switch valve 38 is integrated into the pipeline 31 to the heat exchanger 27, to which the third pipeline 35 also connects, which opens directly into the collecting pot 6 of the washing compartment 2. It is thus permitted that fresh water originating from the second fresh water tank 23 can optionally be conveyed through the heat exchanger 27 or directly into the collecting pot 6 or into the washing area 2. This offers the possibility of dividing the tank volume made available by the second fresh water tank 23 for different wash program sections, so that fresh water preheated to room temperature of e.g. 23 ° C can be fed to the wash container 2 at different wash program times. In particular, it is possible to use fresh water warmed up to room temperature for an intermediate rinse. As a result, components and loads are cooled less than if, as is customary according to the prior art, cold fresh water of e.g. 15 ° C from the fresh water line 14 is used for the intermediate rinsing.

When the heat exchanger 27 is used as intended, it is flowed through by fresh water from the fresh water tank 23 on the one hand and by previously heated washing liquor from the collecting pot 6 on the other hand. A heat transfer then takes place in the heat exchanger 27 from the hot washing liquor to the fresh water, with the result that fresh water which is still further heated is available, which is then available for further washing program sections.

When the heated fresh water leaves the heat exchanger 27, it must first be temporarily stored in a tank. It cannot be passed directly from the heat exchanger 27 into the washing area 3, since the remaining washing solution is still being pumped out here. The fresh water tank 17 serves to store the fresh water heated by means of the heat exchanger 27, with a quasi-synergetic advantage.

With the interposition of the heat exchanger 27, the second pipeline 31 therefore leads from the second fresh water tank 23 to the first fresh water tank 17.

The fresh water heated in the heat exchanger 27 is stored in the first fresh water tank 17 until it is needed for the rinsing process, for example for a final rinse.

In order to carry out the most efficient heat transfer possible in the heat exchanger 27, the cross-sections in the coaxial heat exchanger 27 are to be kept small. For this it is advisable to use filtered washing liquor from the sieve system of the collecting pot 6 in order to avoid conveying coarse dirt through the heat exchanger 27. According to the illustration after Fig. 1 a separate heat exchanger pump 33 is used for conveying the filtered washing liquor. This promotion is similar to pumping out, because after the heat exchange, the cooled washing solution should be led out of the dishwasher. To ensure that the caustic solution is reliably directed, the wash liquor must pass through a non-return valve in front of or behind the heat exchanger as well as a caustic overstroke. For functional integration, the lye feed from the heat exchanger 27 is brought together with the lye feed from the collecting pot 6 immediately before or within the caustic excess stroke.

The construction according to the invention allows a method to be carried out, as it is based on Fig. 28 is shown in a schematic flow diagram. Thereafter, the following procedure is preferred as follows:
Before the start of a new wash program, the first fresh water tank 17 and the second fresh water tank 23 are filled with fresh water. This fresh water is warmed up to room temperature. According to 100, a new wash program begins.

The washing program includes cleaning. A fresh water inlet takes place at the beginning of this washing program section. In this case, according to 101, the fresh water tank 17 is emptied into the washing area 3. The tank volume of the fresh water tank 17 can be 2.8 l, for example. Since this amount is not yet sufficient for cleaning, further fresh water is fed into the washing chamber 3 via the fresh water line 14 and the supply line 16 according to 102. With a tank volume of the first fresh water tank 17 of approx. 2.8 l, one is required Supply of fresh water via the fresh water line 14 of approx. 0.65 I.

During the cleaning according to 103, the wash liquor in the wash compartment 2 and the load are first heated to the program-related cleaning temperature. After the heating has been switched off, the remaining temperature will continue to flush for a certain period of time. After cleaning, according to 104, there follows a draining phase with a subsequent pumping process or partial pumping using the drain pump 12.

At this point, according to 105, the heat transfer is carried out in that at the same time according to 106 washing liquor and according to 107 fresh water are conveyed from the second fresh water tank 23 through the heat exchanger 27. Approx. 2.8 l of washing liquor and approx. 2.75 l of fresh water are passed through the heat exchanger 27.

The cooled washing liquor that has left the heat exchanger 27 is directly conveyed away and discarded, whereas the heated fresh water is stored in the first fish water tank 17.

The amount of water in the wash liquor that is conveyed through the heat exchanger 27 does not fully correspond to what was passed into the wash cabinet at the start of the process, since some of the water sticks to the load in the dishwasher and, if filtered wash liquor is used for the heat exchange, still water remains in the lower sump of the sump 6 in front of the drain pump. After the washing liquor has been conveyed away with the heat exchanger pump 33, the remaining washing liquor is then briefly pumped out of the collecting pot 6 according to 108 by using the waste water pump 12 to convey away the washing liquor and coarse dirt remaining in the lower sump of the collecting pot 6.

At the same time, the draining phase is continued according to 109 and, if necessary, pumping takes place according to 110.

A short rinsing step follows for further removal of dirt particles. For this purpose, water according to 111 is fed from the fresh water line 14 into the collecting pot, preferably in an amount of approx. 0.7 I. The actual short rinsing step then follows according to the lower spray arm is guided. Then takes place according to 113 a pumping out.

After the short rinse step, there is an intermediate rinse. In order to cool down the load as little as possible, the remaining fresh water from the second fresh water tank 23, which is warmed up to room temperature, is used for this instead of fresh water coming from the fresh water line 14. For this purpose, fresh water is pumped from the second fresh water tank 23 in an amount of approx. During the intermediate rinsing according to 115, the fresh water heated by the heat exchange in the heat exchanger 27 remains in the first fresh water tank 17.

At the end of the intermediate wash, the wash liquor located in wash space 2 is pumped out according to 116. At this point, too, a short rinse step is carried out to further remove dirt particles to improve the washing result. For this purpose, water is initially supplied from the fresh water line 14 according to 117. Compared with the first short rinsing step according to 112, however, only a smaller amount of water is fed from the feed line 14 into the collecting pot 6, for example 0.5 l. The actual short rinsing step then takes place in accordance with 118. After completion of this short rinsing step, the water previously introduced into the collecting pot 6 is pumped out according to 119.

After the second short rinse step, there is a final rinse. Since the final rinse includes a heating phase, it makes sense to use the fresh water from the fresh water tank 17, which was previously preheated by the heat exchange, at this point. This significantly reduces the heating energy required. According to 120, there is consequently a water inflow from the first fresh water tank 17.

During the final rinse in accordance with 121, the washing liquor is initially heated to a defined final rinse temperature, similar to cleaning, including the load, and after this temperature has been reached, rinsing continues for a certain period of time without further reheating. At the end of the final rinse, the washing solution is completely pumped out. In order to clean the heat transfer 27, it makes sense to discharge partial quantities via the heat transfer 27 according to 122. Complete pumping then takes place in accordance with 123.

After the final rinse, there follows a drying phase that begins at 124.

During the drying phase, according to 125 and 126, the first fresh water tank 17 and the second fresh water tank 23 are filled with fresh water, so that these amounts of water can absorb heat from the environment until the next wash program.

The drying phase is then ended at 127. And at 128, the washing program carried out as intended ends.

The others Figures 4 to 7 and 20th and 29 to 31 indicate constructive variants in each case.

Fig. 4 shows that using Fig. 1 The fluidic connection of the first fresh water tank 17 and the second fresh water tank 23 by means of the first pipeline 25 as described above. The second fresh water tank 23 can then be filled by specifically overfilling the first fresh water tank 17. This construction is very simple and represents an inexpensive embodiment.

According to the in Fig. 5 An additional switchover valve 39 is provided, which is connected to the fresh water line 14 downstream of the switchover valve 15 in terms of flow. The second fresh water tank 23 can thus be filled directly from the fresh water line 14. This allows a more flexible filling of the second fresh water tank 23 that is independent of the fill level of the first fresh water tank 17.

Fig. 6 shows the fluidic connection between the second fresh water tank 23 and the heat exchanger 27. This is implemented by means of a pipe 31 into which the pump 32 is integrated. According to this construction, the fresh water tank 23 is always emptied with the interposition of the heat exchanger 27.

Fig. 7 shows an alternative embodiment to this, as it has already been shown on the basis of Fig. 1 is described. According to this embodiment, a switchover valve 38 is integrated into the pipeline 31, to which a third pipeline 35 is also connected. At the other end, the third pipeline 35 opens into the collecting pot 6. So is Optionally, depending on the position of the switching valve 38, the pipeline 31 or the pipeline 35 can be charged with fresh water from the fresh water tank 23.

Fig. 8 FIG. 11 shows a construction which enables the fresh water heated by the heat exchange to be stored in the first fresh water tank 17. For this purpose, the already described pipeline 31 is provided, which fluidically connects the second fresh water tank 23 to the first fresh water tank 17. In order to keep the waterways as short as possible, it is preferred to run the section of the water line 31 between the heat exchanger 27 and the first fresh water tank 17 above the washing compartment 2. The heated fresh water can be stored in the tank 17 or passed into the collecting pot 6 for further use via the outlet or shut-off valve 15 already present on the tank 17.

Fig. 9 shows an alternative embodiment according to which an additional tank 40 is provided. This tank 40 is preferably designed as a side wall tank and is arranged on the outside of the washing compartment 2 opposite the first tank 17. The tank 40 is in fluidic connection with the collecting pot 6 via a pipeline 41, a shut-off valve 42 being integrated into the pipeline 41. The short waterways are particularly advantageous of this configuration.

Another alternative shows Fig. 10 , whereby a suction lifter 43 for emptying the tank 40 is provided here instead of a shut-off valve 42.

Fig. 11 shows an embodiment according to which a separate heat exchanger pump 33 is provided for conveying the washing liquor into the heat exchanger 27. Rinsing liquor filtered by means of the pump 33 is preferably used from the sieve system. As a result, smaller cross-sections can be used in the heat exchanger 27, as a result of which a very efficient heat exchange is made possible.

According to an alternative embodiment, as shown in Fig. 12 is shown, instead of a separate pump 33, the sewage pump 12, which is already present, is used to charge the heat exchanger 27 with washing liquor. Here, the cross-sections of the heat exchanger 27 must be kept correspondingly large so that no coarse dirt particles can clog the heat exchanger 27.

According to a further alternative Fig. 13 the wash liquor is conveyed directly with the circulating pump 7 provided. For this purpose, a corresponding feed line, which leads to the heat exchanger 27, must be connected to the water switch 8.

Another embodiment shows Fig. 14 . A water line with a shut-off valve 44 is then inserted into the pressure area of the circulation pump 7. If this valve 44 is opened, a bypass is switched on for the washing solution, through which the washing solution reaches the heat exchanger 27.

The representation after Fig. 15 shows an embodiment according to which the heat exchanger 27 is connected directly to the sewer line 13. In the normal operating case, the entire waste water is conveyed through the heat exchanger 27 by means of a waste water pump 12 and transported away.

the Figures 16 and 17 show an alternative embodiment to this, according to which it is provided that a return line from the heat exchanger 27 and the sewage line 13 are brought together behind the sewage pump 12. The merging can be positioned in front of or behind the suds lift. Another check valve 45 is used for the return line from the heat exchanger 27.

Fig. 18 shows an embodiment according to which the line 34 going out from the heat exchanger 27 and leading to the water line 13 is at least partially passed through the base area of the second fresh water tank 23. Residual heat in the waste water can thus be transferred to the fresh water stored in the second fresh water tank 23, which serves to further heat the fresh water.

Possible designs according to the construction Fig. 18 are in the Figures 29, 30 and 31 shown.

Fig. 29 shows the second fresh water tank 23 in a schematic perspective illustration. This has a base area 46. The pipeline 34 is laid in the base area 46, with different laying patterns being conceivable. Fig. 30 shows a meandering layout, whereas Fig. 31 shows a spiral laying.

The heat exchanger 27 is preferably arranged on a side wall 47 of the washing compartment 2. Different embodiments of the heat exchanger 27 are shown in Figures 19 to 26 shown.

Fig. 19 shows a coil of straight, horizontal elements with 180 ° bends.

Fig. 20 shows a pipe coil with inclined instead of horizontal elements. This improves the heat transfer 27 from running empty.

Fig. 21 shows a pipe coil which also has vertical, straight elements.

Fig. 22 shows a pipe coil with an inward and outward spiral shape, as a result of which a greater length of the heat exchanger 27 is achieved. The spiral shape can have straight or curved tubular elements.

Fig. 23 shows a heat exchanger 27 in a vertical orientation, an inclined one also being possible.

Fig. 24 shows a pipe snake with a 180 ° bend, concentric bends and inclined parallel guides.

Fig. 25 shows a heat exchanger 27 in a vertical orientation, completely without bends. As a result, the inner tube 28 can be guided optimally coaxially.

Fig. 26 shows a meandering pipe coil, which is clearly lengthened by the course in two levels.

For improved energy efficiency, the spaces between the coaxial heat exchanger 27 should be filled with insulating material. This will reduce the heat loss from the device.

Fig. 27 Finally, FIG. 3 shows an embodiment with a double feed pump 48. This allows washing liquor and fresh water to be conveyed simultaneously through the heat exchanger 27. A single motor 49 controls two feed chambers 50 and 51 for different water volumes.

Reference number

1

dishwasher

2

Rinsing container

3

Wash cabinet

4th

Spraying device

5

Spray arm

6th

Collecting pot

7th

Circulation pump

8th

Water switch

9

supply line

10

supply line

11

supply line

12th

Sewage pump

13th

Sewer pipe

14th

Fresh water pipe

15th

Changeover valve

16

Feed line

17th

Fresh water tank

18th

Tank line

19th

Overflow

20th

Overflow pipe

21

Changeover valve

22nd

Check valve

23

second fresh water tank

24

Overflow

25th

first pipeline

26th

Vent line

27

Heat exchanger

28

Inner tube

29

Outer tube

30th

Annular gap

31

second pipeline

32

pump

33

Heat exchanger pump

34

Pipeline

35

third pipeline

36

arrow

37

arrow

38

Changeover valve

39

Changeover valve

40

tank

41

Pipeline

42

Check valve

43

Suction cup

44

Shut-off valve

45

check valve

46

Base area

47

Side wall

48

Double delivery pump4e

49

engine

50

Delivery chamber

51

Delivery chamber

100 to 128

Process step

Claims (11)

1. Dishwasher, in particular a domestic dishwasher, comprising a washing container (2) which provides a washing chamber (3) and is used for receiving washware to be cleaned, and comprising a fresh water tank (17), the fresh water tank (17) being fluidically connected to the washing container (2), characterised by a second fresh water tank (23) and a heat exchanger (27), the second fresh water tank (23) being fluidically connected to the first fresh water tank (17) by means of a first pipeline (25) on the one hand and by means of a second pipeline (31) with the interposition of the heat exchanger (27) on the other hand.
2. Dishwasher according to claim 1,
   characterised in that
   the first fresh water tank (17) has an overflow (24) to which the first pipeline (25) is fluidically connected.
3. Dishwasher according to either claim 1 or claim 2,
   characterised in that
   the second fresh water tank (23) is fluidically connected to the washing container (2) by means of a third pipeline (35).
4. Dishwasher according to claim 3,
   characterised in that
   the third pipeline (35) branches off from the second pipeline (31) with the interposition of a switching valve (38), the switching valve (38) being fluidically connected upstream of the heat exchanger (27).
5. Dishwasher according to any of the preceding claims,
   characterised in that
   the heat exchanger (27) is fluidically connected to a wastewater line (13) which opens into the washing container (2) at the other end.
6. Dishwasher according to any of the preceding claims,
   characterised in that
   the heat exchanger (27) is a coaxial heat exchanger.
7. Dishwasher according to any of the preceding claims,
   characterised in that
   the heat exchanger (27) has an inner tube (28) made of stainless steel and an outer tube (29) which is made of plastic and accommodates the inner tube (28) while leaving an annular gap (30).
8. Dishwasher according to any of the preceding claims,
   characterised in that
   the first fresh water tank (17) is arranged as a side tank next to the washing container (2).
9. Dishwasher according to any of the preceding claims,
   characterised in that
   the second fresh water tank (23) is arranged as a base tank below the washing container (2).
10. Method for operating a dishwasher according to any of the preceding claims,

    - in which the first fresh water tank (17) is supplied with fresh water in order to fill the first and the second fresh water tank (17, 23),

    - in which fresh water in the first fresh water tank (17) is fed into the washing container (2) at the start of a cleaning program,

    - in which, when the cleaning program ends, the washing solution in the washing container (2) is pumped out and discarded,

    - the washing solution being conducted through the heat exchanger (27) in counterflow with fresh water originating from the second fresh water tank (23)

    - and the fresh water originating from the second fresh water tank (23) being fed into the first fresh water tank (17) and stored there after passing through the heat exchanger (27),

    - in which, at the start of a final rinse program, the fresh water in the first fresh water tank (17) is fed into the washing chamber (2).
11. Method according to claim 10, in which an intermediate rinse program is carried out before the final rinse program, wherein fresh water is transferred from the second fresh water tank (23) into the washing container (2) at the start of the intermediate rinse program.

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