EP1864603B1 - Dishwasher with heat recovery - Google Patents

Description

The invention relates to a dishwasher with heat recovery according to the preamble of claim 1.

In dishwashers, the dishes to be washed are cleaned with process water in several consecutive process phases. As a rule, the water is heated in at least two of these process phases.

In order to reduce the energy consumption, it has been proposed to transfer heat by means of special heat storage from one process phase to the next.

document DE-A-3 901 169 discloses a dishwasher with such a heat storage and DE-U-29518630 discloses a dishwasher with a water decalcifying device.

It has as its object to provide a dishwasher of the type mentioned, which realizes the heat transfer between process phases in a simple way. This object is achieved by the dishwasher according to claim 1.

According to the claim, the dishwasher thus has heat transfer means which are able to transfer heat between the process water and the water decalcification device of the device. The heat transfer means are controlled by the controller of the dishwasher in such a way that they transport heat from the process water into the water decalcifier in a first process phase in order to then transport this heat from the water decalcifier back into the process water in a second, later process phase.

Thus, the Wasserentkalkungsvorrichtung the device is used as a heat storage. Since this has a relatively large thermal mass and is present anyway in each device, it is particularly suitable as a buffer for heat. Thus, a separate heat storage omitted entirely or at least smaller.

In general, the Wasserentkalkungsvorrichtung has a brine tank for receiving brine. Preferably, the heat transfer means are configured to transfer heat between that received in the brine tank Solewasser and the process water can transfer. In other words, in this case, the brine water is used as a heat storage.

• Fig. 1 eine erste Ausführung eines erfindungsgemässen Geschirrspülers,
• Fig. 2 eine zweite Ausführung des Geschirrspülers,
• Fig. 3 eine dritte Ausführung des Geschirrspülers und
• Fig. 4 eine vierte Ausführung des Geschirrspülers.

Further preferred embodiments will become apparent from the dependent claims and from the following description with reference to FIGS. Showing:

• Fig. 1 A first embodiment of a dishwasher according to the invention,
• Fig. 2 a second embodiment of the dishwasher,
• Fig. 3 a third embodiment of the dishwasher and
• Fig. 4 a fourth embodiment of the dishwasher.

The in Fig. 1 shown dishwasher has a tub 10 for receiving the dishes to be washed. In the tub 10 spray arms 11 or other spray devices are arranged in a conventional manner, with which process water can be sprayed onto the dishes. At the tub 10, a process water circuit is connected, with which the process water can be pumped. This has a suction tube 12, with which the water can be sucked out of the sump 13 of the tub. From the suction pipe 12, the water passes to a pump 14, from where it is conveyed via lines 15 to the spray arms 11.

For the supply of water in the device, a supply line 16 is provided, from which water via three valves 17, 18, 19 can be tapped. These valves, as well as all other functions and components of the device, are controlled by a controller (not shown).

By opening the first valve 17 fresh water can be passed directly into the sump 13 of the tub 10. Alternatively or additionally, by opening the second valve 18 water via a Wasserentkalkungsvorrichtung 20 also in the sump 13th be initiated. The valve 17 and the corresponding supply line can also be omitted in simple models.

The desalination apparatus 20 comprises a brine container 21 and a resin container 22. In the resin container 22, an ion exchange resin is arranged, with which water can be softened in a conventional manner. In order to regenerate the resin, brine tank 21 is provided with brine water. These are usually salt water. By opening the third valve 19, the brine water can be passed through the resin container 22 so as to perform regeneration.

For discharging contaminated process water, the device has a drain 23 with a drain pump 24.

According to the invention, as already mentioned, heat transfer agents are provided, which are described below.

In the execution after Fig. 1 The heat transfer means comprise a transfer circuit 25, which is shown with a bold line. Therein, a heat transfer medium is pumped by a circulation pump 26 between a first heat exchanger 28 and a second heat exchanger 29. The heat transfer medium may be, for example, water or another fluid.

The first heat exchanger 28 is arranged at the process water circuit, while the second heat exchanger 29 is located at the Wasserentkalkungsvorrichtung 20. In the execution after Fig. 1 the first heat exchanger 28 is thermally connected to the suction pipe 12, and the second heat exchanger 29 to the brine tank 21st

The function of the device after Fig. 1 is as follows:

For rinsing the dishes, the process phases described above are performed.

For example, the dishes are pre-rinsed in a first process phase, the pre-rinse phase.

Then the process water is pumped off and fresh water is supplied for the following main cleaning phase. This is pumped by the pump 14 and heated by a (not shown) heater. At the same time a dishwashing detergent is added.

Then, a Zwischenenspülphase take place, in which the water is replaced by fresh water and the dishes are rinsed again.

Finally, after at least one further change of the process water, a final rinse phase for rinsing the dishes after addition of a rinse aid follows.

In the described method, the heat transfer means are used to transfer heat via the water decalcification device 20 from a first process phase to a later, second process phase. The terms "first process phase" and "second process phase" designate those process phases in which heat is transferred between the process water and the descaling device - the terms are not to be interpreted as meaning that the first process phase is necessarily the process phase that is carried out at the beginning of the cleaning process, and the second process phase does not necessarily follow directly to the first phase of the process.

The removal of heat takes place as possible towards the end of the first process phase before or during the pumping out of the process water. For this purpose, the pumps 14 and 26 are put into operation, for example, during 2 to 3 minutes, so that the heated process water flows through the suction pipe 12 there to give heat in the first heat exchanger 28 to the heat transfer medium. The heated heat transfer medium is conveyed by the pump 26 to the second heat exchanger 29, where it in turn emits heat to the Wasserentkalkungsvorrichtung 20 and in particular to the brine.

Preferably, the first process phase, from which the heat is extracted, is the main cleaning phase, as this is usually the first phase in which the process water is heated to a high temperature.

After completion of the first process phase, the process water is at least partially replaced by fresh water, whereby the temperature in the tub decreases. It may then optionally follow one or more process phases in which the pump 26 remains switched off and the heat is stored in the descaling device 20. If the first process phase is e.g. the main cleaning phase, the pump 26 may be switched off in the following intermediate flushing phase.

• die Klarspülphase, da in dieser das Prozesswasser in der Regel nochmals stark erwärmt werden soll, oder
• die Zwischenspülphase zwischen der Hauptreinigungsphase und der Klarspülphase.

The second process phase in which the heat is conveyed from the descaling device back into the process water is, for example:

• the rinse phase, since in this process water is usually to be strongly heated again, or
• the intermediate rinse phase between the main cleaning phase and the final rinse phase.

The heat transfer from the desalination device 20 to the process water preferably takes place at the beginning of the second process phase by switching on the pumps 14 and 26. The pump 26 is operated, for example, as long as the temperature of the transfer medium is higher by a threshold than that of the process water. At the same time or subsequently, heat can also be supplied to the process water with a heater arranged in the process water circuit. Preferably, the heater is activated only after completion of the heat transfer, since otherwise the Wasserentkalkungsvorrichtung less heat can be removed.

During the heat transfer in the second process phase, the pump 14 is preferably operated at reduced power, so that the process water exits only via the lower spray arm and does not act on the dishes. This allows a larger amount of heat to be transferred from the water decalcification device, as if the process water already ran during the heat transfer over the hot dishes and would heat up in this way faster. Only after completion of the heat transfer, the pump is operated with higher power.

A second embodiment of the invention is in Fig. 2 shown. This differs from the execution Fig. 1 in that the first heat exchanger 28 is not arranged on the suction tube 12 but on one of the lines 15 downstream of the pump 14. Preferably, the first heat exchanger 28 is in this case on the line to the lower spray arm, so that in the manner already described during the heat transfer in the second process phase, the pump 14 can be operated with reduced power.

A third embodiment of the invention is disclosed in Fig. 3 shown. It differs from the execution Fig. 1 in that no separate circuit is provided for a heat transfer medium. Rather, the heat transfer means are designed so that they can direct process water through the second heat exchanger 29. For this purpose, a changeover switch 32 is provided in the process water circuit, with which the process water can be selectively guided either directly to the spray arms 11 or first through the second heat exchanger 29 and only then to the spray arms 11.

In order to exchange heat between the process water and the water descaling device 20, the process water from the controller of the device is passed through the second heat exchanger 29, while in normal operation of the device, the switch 32 is set so that the water from the pump 14 directly to the spray arms 11th flows.

Switch 32 may also be continuously controllable and, for example, conduct only a portion of the water through the heat exchanger 29.

In the third embodiment, the first heat exchanger and the pump 26 can be omitted.

A fourth embodiment of the invention is in Fig. 4 shown. It differs from the execution Fig. 1 again in that no separate circuit is provided for a heat transfer medium. In this embodiment, the heat transfer means are configured so that they can convey brine through the first heat exchanger 28. For this purpose, the brine from the brine tank 21 with the pump 26 to the first heat exchanger 28 and then be promoted back.

To exchange heat between the process water and the Wasserentkalkungsvorrichtung 20, only the pump 26 needs to be activated in this case.

In the fourth embodiment, the second heat exchanger can be omitted.

The different variants described so far can also be combined. For example, in the embodiment according to Fig. 4 the first heat exchanger 28 also, as in the embodiment according to Fig. 2 shown to be arranged after the pump 14.

In the following, some variants of the invention are described, which, as far as appropriate, can also be combined with all of the embodiments described above.

For example, the heat capacity of the water descaling device 20 can be increased by selecting the brine container larger than conventional devices, and e.g. is set at 2 to 3 liters.

Preferably, a thermal insulation is arranged around the brine tank 21, so that the heat can be stored longer in the water decalcification device 20.

The first heat exchanger 28 can also be arranged at the outlet 23, so that the heat transfer from the process water to the water decalcification device 20 takes place only when pumping off at the end of the first process phase. In order to provide in this case, a heat transfer from the Wasserentkalkungsvorrichtung 20 back into the process water, for example, the supply line for the process water can be passed through a heat exchanger which is in contact with the Wasserentkalkungsvorrichtung 20. Or it can additionally be arranged a heat exchanger in the process water circuit.

The first heat exchanger 28 can also be arranged on the sump 13 or elsewhere on the tub 11.

In the comments after Fig. 1 and 2 the heat transfer means are equipped with a transfer circuit 25 for a heat transfer medium. Alternatively, the heat transfer agent can also be configured as an actual heat pump by an expansion valve is provided between the two heat exchangers 28 and 29 in a conventional manner, so that (depending on the direction of the pump 26) one of the two heat exchangers as evaporator and the other Capacitor works. This makes it possible to improve the heat transfer efficiency.

In the embodiments shown so far, primarily the brine tank 21 and the brine placed therein act as heat storage. Additionally or alternatively, the resin container 22 and the water therein can be used as a heat storage.

Claims (11)

1. Dishwasher with a vat for receiving the dishes to be washed, with a water decalcifying device (20), and with a controller, wherein the controller is formed in a way to clean the dishes with process water in multiple subsequent process phases, wherein the dishwasher has heat transfer means (25, 26, 28, 29) for transferring heat from the process water and vice versa, characterized in that the heat transfer means (25, 26, 28, 29) are formed to transfer heat from the process water in the water decalcifying device (20) and vice versa, wherein the heat transfer means(25, 26, 28, 29) are controlled by the controller in such a way, that they transport heat from the process water into the water decalcifying device (20) in a first process phase and heat from the water decalcifying device (20) into the process water in a second, later process.
2. Dishwasher according to claim 1, wherein the controller is formed in a way to exchange the process water between the first and the second process phase at least partly.
3. Dishwasher according to one of the preceding claims, wherein the water decalcifying device (20) has a brine container (21) for receiving brine water, wherein the heat transfer means (25, 26, 28, 29) are formed in a way to transfer heat between the brine water received in the brine container (21) and the process water.
4. Dishwasher according to claim 3, wherein a thermal isolation is provided around the brine container (21).
5. Dishwasher according to one of the preceding claims, wherein a process water circuit (15) for transferring process water is arranged at the vat, and wherein the heat transfer means (25, 26, 28, 29) has at least a first heat exchanger (28) arranged at the process water circuit (15) or at a drain (23).
6. Dishwasher according to claim 5, wherein the heat transfer means (25, 26, 28, 29) has means (26) for conveying brine water through the first heat exchanger (28).
7. Dishwasher according to one of the preceding claims, wherein the heat transfer means (25, 26, 28, 29) has a second heat exchanger (29), arranged at the water decalcifying device (20).
8. Dishwasher according to claim 5 and 6 and claim 7, wherein the heat transfer means (25, 26, 28, 29) has a transfer circuit (25) and a circuit pump (26),
   wherein a heat transfer medium may be pumped by the circuit pump (26) between the first and the second heat exchanger (29) through the transfer circuit (25).
9. Dishwasher according to one of the claims 7 or 8, wherein the heat transfer means (25, 26, 28, 29) has means (32) for conducting process water through the second heat exchanger (29).
10. Dishwasher according to one of the preceding claims, wherein the first process phase is a main cleaning phase for cleaning the dishes after adding a dishwashing liquid.
11. Dishwasher according to one of the preceding claims, wherein the second process phase is a rinsing phase for rinsing the dishes after adding a rinse aid, or
    wherein the second phase is an intermediary rinsing phase between the main cleaning phase for cleaning the dishes after adding a dishwashing liquid and a rinsing phase for rinsing the dishes after adding a rinse aid.

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