US20110005557A1

US20110005557A1 - Dishwasher and method for cleaning wash ware

Info

Publication number: US20110005557A1
Application number: US12/921,639
Authority: US
Inventors: Harry Braun; Harald Disch; Markus Heidt; Klaus Padtberg
Original assignee: Premark FEG LLC
Current assignee: Premark FEG LLC
Priority date: 2008-03-11
Filing date: 2009-03-03
Publication date: 2011-01-13
Also published as: DE102008013549A1; EP2254453B1; CN101969830A; CA2717338C; WO2009114337A1; CA2717338A1; CN101969830B; EP2254453A1

Abstract

A method, and related dishwasher, for cleaning wash ware that provides a wash phase followed by a rinse phase, in which rinse fluid is conducted into a treatment chamber (2) of the dishwasher (1). The rinse phase is composed of a fresh-water rinse phase and a steam rinse phase. During the fresh-water rinse phase, a rinse liquid is sprayed into the treatment chamber (2). During the steam rinse phase, steam is generated and conducted into the treatment chamber (2). A total of 0.5 to 2.0 litres of rinse fluid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber (2) in a top view of the treatment chamber, and preferably 1.0 to 1.7 litres of rinse liquid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber (2) in a top view of the treatment chamber, is sprayed into the treatment chamber (2) during the fresh-water rinse phase.

Description

The invention relates to a dishwasher and to a method for cleaning wash ware in a dishwasher.
The invention relates, in particular, to a method for cleaning wash ware in a dishwasher, in particular a commercial dishwasher, which is in the form of a program-controlled ware washer. Furthermore, the invention relates to a dishwasher, in particular a commercial dishwasher, in the form of a program-controlled ware washer.
Programme-controlled ware washers are dishwashers which can be manually loaded and unloaded. Programme-controlled ware washers (called box-type ware washers or even batch dishwashers) may be called hood-type dishwashers or even hood-type ware washers or may be front loader dishwashers (front loader ware washers). Front loader dishwashers may be under-counter machines, top-counter machines or else free-standing front loaders.
Examples of wash ware include plates, cups, pots, trays, knives, forks, spoons, glasses and other kitchen utensils.
WO 2006/037447 A1 discloses a dishwasher in the form of a program-controlled ware washer, in which the following method steps are run through successively: a wash phase, in which wash liquid is sprayed from a tank by means of wash pump through a wash line system into a treatment chamber and can flow back from the treatment chamber into the tank because of the force of gravity; a rinse phase, in which heated fresh water as the rinse liquid is sprayed from a fresh-water feed line by means of a rinse pump through a rinse line system into the treatment chamber and can flow from the treatment chamber into the tank because of the force of gravity; a steam phase, in which steam is generated from heated fresh water from a fresh-water feed line by means of a steam generator and is conducted into the treatment chamber by the rinse line system. Provision is optionally made for the wash ware to be dried after the steam phase by air being blown in or to be cooled by letting water in. A booster can alternatively be used to heat up the fresh water for the rinsing or for steam generation.
EP 1 738 677 A2 discloses a domestic dishwasher which is designed for the following procedure: a wash phase, during which wash liquid is sprayed by means of a pump from a sump via spray nozzles into a washing chamber which is designed to accommodate wash ware. Wash liquid is then pumped away, and the sump is filled with fresh water which is then conveyed by the same pump as the wash liquid previously to the same spray nozzles as the wash liquid previously. The transition from the sump to the pump contains a heater for heating the wash liquid, with it being possible for the rinse liquid to be heated or left unheated during the rinse phase. The rinse phase is followed by a steam phase, in which fresh water from the sump is evaporated by means of the heater and is conducted via the said spray nozzles into the treatment chamber. The steam phase may be followed by a drying phase, in which the heated wash ware dries.
Commercial dishwashers require water, detergent, rinse aid and energy in order to clean wash ware. The consumption of detergent and rinse aid is proportionally dependant on the water consumption per wash cycle. This is also true of the heating energy at a constant water admission temperature.
A commercial dishwasher usually has two water circuits which are completely separate from each other. These two water circuits comprise a circuit which is responsible for washing and through which used water from the wash tank is conducted, and a fresh-water circuit which is responsible for rinsing and uses fresh water from a boiler.
The main object of the rinse phase is to remove the wash-liquid residues (lye) which are found on the wash ware. The rinse liquid (pure fresh water or fresh water mixed with rinse aid) which is sprayed during the rinse phase flows into the wash tank and then also serves to regenerate the wash liquid.
Before new rinse liquid is conducted into the wash tank during the rinse phase, the same quantity of wash liquid is pumped out of the wash tank.
At the basis of conventional dishwashers which are known from the prior art and are in the form of program-controlled ware washers is a fresh-water or rinse-liquid consumption of 2.4 to 3.5 litres per wash cycle.
The object to be achieved by the invention is to provide a way of reducing the quantity of fresh water and quantity of rinse liquid required for cleaning wash ware, without the efficiency of the cleaning of the wash ware being adversely affected.
The invention achieves this object by means of a method for cleaning wash ware in a dishwasher, in particular in a commercial dishwasher, which is in the form of a program-controlled ware washer and has a treatment chamber for accommodating the wash ware which is to be cleaned, wherein the method has the following program-controlled method steps which are to be executed successively: a wash phase, in which wash liquid is sprayed from a tank (wash tank) by means of a wash pump through a wash line system into the treatment chamber and can flow back into the tank from the treatment chamber because of the force of gravity; and a rinse phase, in which rinse fluid is conducted into the treatment chamber.
The term “rinse fluid” used here is to be understood as meaning any gaseous or vaporous or liquid substance which is sprayed into the treatment chamber of the dishwasher during the rinse phase or is supplied to the treatment chamber of the dishwasher in some other way, with the aim of removing the wash-liquid residues (lye) which are to be found on the wash ware after the wash phase.
With regard to the method for cleaning wash ware, the present invention is characterized in that the rinse phase is composed of a fresh-water rinse phase and a steam rinse phase. During the fresh-water rinse phase, a rinse liquid is sprayed from a rinse-liquid supply device by means of a rinse pump through a rinse line system into the treatment chamber of the dishwasher. The rinse liquid sprayed into the treatment chamber during the fresh-water rinse phase can subsequently flow into the wash tank of the dishwasher because of the force of gravity. A suitable rinse-liquid supply device, from which the rinse liquid is removed during the fresh-water rinse phase, is, in particular, a fresh-water tank, in which fresh water and, if appropriate, rinse aid which is metered into the fresh water are stored, or a boiler, in which the rinse liquid (i.e. the fresh water and the rinse aid which, if appropriate, is metered into the fresh water) can optionally be heated.
During the steam rinse phase, rinse liquid (i.e. pure fresh water or fresh water with rinse aid metered in) is evaporated with the aid of a steam generator connected to a fresh-water feed line, and the steam generated in such a manner is conducted into the treatment chamber of the dishwasher.
It is provided here, as being particularly essential to the invention, that a total of 0.5 to 2.0 litres of rinse liquid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber in a top view of the treatment chamber, and preferably a total of 1.0 to 1.7 litres of rinse liquid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber in a top view of the treatment chamber, are sprayed into the treatment chamber of the dishwasher during the fresh-water rinse phase.
The abovementioned rinse-liquid quantities are each based on a unit area of 500 mm×500 mm, since the accommodating capacity of a dishwasher in the form of a program-controlled ware washer is usually described or can be described with the aid of the unit area size of 500 mm×500 mm. This unit area size is derived from the area of a utensil basket customarily used in a dishwasher.
As a rule, the area of a utensil basket used for inserting the wash ware into the treatment chamber of the dishwasher is 500 mm×500 mm. A dishwasher, the treatment chamber of which is designed for accommodating a single utensil basket, is therefore approximately 500 mm×500 mm in size in a top view of the treatment chamber. A dishwasher which is designed for simultaneously accommodating two utensil baskets therefore has a treatment chamber which has, in a top view of the treatment chamber, an area which is enclosed by the wall of the treatment chamber and corresponds to two unit areas of 500 mm×500 mm.
The present invention is based on the finding that the steam conducted into the treatment chamber during the steam rinse phase can be used for removing residue wash liquid, in particular lye, from the surfaces of the wash ware. Accordingly, it is possible for only some of the wash-liquid residues remaining on the surfaces of the wash ware after the wash phase to be rinsed off during the fresh-water rinse phase, by the rinse liquid being sprayed into the treatment chamber of the dishwasher. The remaining amount of wash-liquid residues is removed with the aid of the steam conducted into the treatment chamber of the dishwasher during the steam rinse phase.
Owing to the fact that, according to the invention, the rinse phase is composed, firstly, of a fresh-water rinse phase and, secondly, of a steam rinse phase, the total water consumption per cleaning cycle can be reduced, with the energy to be applied per cleaning cycle and the chemical costs being reduced at the same time.
Tests have shown that steam which condenses on the surfaces of wash ware has extremely good rinsing-off effects. The steam introduced into the treatment chamber of the dishwasher during the steam rinse phase is distributed uniformly in the treatment chamber in accordance with the second fundamental law of thermodynamics, and therefore said steam which is introduced into the treatment chamber in particular even reaches wash-ware shadow zones which may possibly be present, i.e. surfaces of the wash ware which are not directly reachable by the spray jet. Put another way, this means that the steam introduced into the treatment chamber of the dishwasher during the steam rinse phase reaches every surface of the wash ware within the treatment chamber irrespective of the position and the orientation of the surface of the wash ware and can be deposited substantially in equal parts (uniformly) on the surfaces of the wash ware. This advantageous effect cannot be achieved in the case of a rinse phase which merely comprises a fresh-water rinse phase, in which rinse liquid rather than any steam is sprayed into the treatment chamber.
Surfaces of wash ware, which, on account of their geometrical shape, do not permit fluid to flow off from them because of gravity, i.e. do not permit liquid to flow off from them because of the force of gravity, provide restrictions with regard to the use of steam as a rinsing medium. These restrictions may occur, for example, in the case of wash ware having depressions in the base, such as, for example, in the case of small bowls or glasses, if said wash ware is correspondingly positioned in the treatment chamber of the dishwasher and the orientation of at least some of the surfaces of the wash ware does not permit liquid to flow off from them in a gravity-induced manner.
The restriction discussed above means that a steam rinse phase alone is, under some circumstances, not sufficient as a rinse phase to achieve a good cleaning result. For this reason, according to the present invention, the rinse phase used for rinsing off the wash-liquid residues remaining on the surfaces of the wash ware after the wash phase is composed of the steam rinse phase and the fresh-water rinse phase. It has been shown that only the combination of a fresh-water rinse phase and a steam rinse phase supplies a thoroughly satisfactory cleaning result.
In comparison to a rinse phase carried out in a conventional dishwasher known from the prior art, with the solution according to the invention, in which the fresh-water rinse phase is employed in conjunction with the steam rinse phase, the quantity of fresh water used in total during the rinse phase can be significantly reduced.
In a preferred realization of the method according to the invention, it is provided that a standard wash phase is followed by the previously described fresh-water rinse phase carried out with a reduced quantity of fresh water of 0.5 to 2.0 litres, and preferably with a reduced quantity of fresh water of 1.0 to 1.7 litres. This fresh-water rinse phase is followed by the steam rinse phase, in which the wash-liquid residues still remaining on the surfaces of the wash ware after the fresh-water rinse phase are completely rinsed off with the aid of the steam introduced into the treatment chamber of the dishwasher. This steam rinse phase employs a total quantity of fresh water of 0.05 to 0.25 litre, and preferably a quantity of fresh water of 0.10 to 0.15 litre in steam form. The quantities of fresh water stated for this preferred realization of the solution according to the invention are always based on a dishwasher in the form of a program-controlled ware washer, the treatment chamber of which is designed for a utensil basket of 500 mm×500 mm, and therefore a unit area of 500 mm×500 mm is enclosed by the wall of the treatment chamber in a top view of the treatment chamber.
In the abovementioned, preferred realization of the solution according to the invention, the steam rinse phase lasts for a total of approximately 5 to 60 seconds, and preferably for a total of approximately 10 to 30 seconds.
Following the steam rinse phase, a condensation and draining phase is then carried out, which phase lasts for a defined time, and in which the steam conducted into the treatment chamber of the dishwasher during the steam rinse phase can at least partially condense on the surfaces of the wash ware, can drain and flow into the wash tank because of the force of gravity. The abovementioned condensation and draining phase preferably lasts for approximately 10 to 60 seconds, and even more preferably approximately 20 to 30 seconds.
In comparison to the currently customary cleaning methods used in dishwashers—in the case of the abovementioned preferred realization of the method according to the invention, approx. 1 litre of fresh water and a corresponding quantity of detergent and rinse aid and approx. 50 to 200 kJ of energy can be saved per wash or rinsing cycle.
The object on which the invention is based is achieved with regard to the apparatus by means of a dishwasher, in particular by means of a commercial dishwasher, in the form of a program-controlled ware washer which is designed for executing the above-described method according to the invention. In this case, the dishwasher has a program-control device for executing at least one cleaning program; a treatment chamber into which wash ware can be manually inserted and from which said wash ware can be removed; a tank (wash tank) down into which liquid from the treatment chamber can flow because of the force of gravity; a wash system with a wash pump and a wash line system for conveying wash liquid from the wash tank through wash nozzles into the treatment chamber during a wash phase; a fresh-water rinse system with at least one rinse pump and at least one rinse line system for conveying rinse liquid from a fresh-water supply device through rinse nozzles into the treatment chamber during a fresh-water rinse phase; and a steam rinse system with a steam generator, which is connected to a fresh-water feed line, for generating steam and for conducting the steam via a steam line into the treatment chamber during a steam rinse phase. In this case, the program-control device is designed in such a manner that first the wash phase, then the fresh-water rinse phase and thereafter the steam rinse phase are executed.
The dishwasher according to the invention is distinguished in that the program-control device and the fresh-water rinse system controlled by it are designed to spray a total of 0.5 to 2.0 litres of rinse liquid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber in a top view of the treatment chamber, and preferably a total of 1.0 to 1.7 litres of rinse liquid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber in a top view of the treatment chamber, during the fresh-water rinse phase.

The invention is described below using preferred embodiments of the dishwasher according to the invention with reference to the attached drawings, in which

FIG. 1 schematically shows a dishwasher, in particular a commercial dishwasher, in the form of a program-controlled ware washer, according to a first embodiment; and

FIG. 2 schematically shows a dishwasher, in particular a commercial dishwasher, in the form of a program-controlled ware washer, according to a second embodiment.

The dishwasher 1 according to the invention contains a treatment chamber 2 for cleaning wash ware (not illustrated). A wash tank 4 in which liquid can flow back out of the cleaning chamber 2 because of the force of gravity is arranged under the treatment chamber 2. The wash tank 4 can be covered at the transition to the treatment chamber 2 with the aid of a strainer (not illustrated). The wash tank 4 contains wash liquid 6, which is usually water, to which detergent can optionally be automatically supplied by a detergent-metering apparatus (not illustrated). The wash liquid 6 can be conveyed by a wash pump 8 via a wash line system 10 to wash nozzles 7 and 9 and can be sprayed through said wash nozzles 7, 9 in the treatment chamber 2 onto the wash ware to be cleaned. The sprayed wash liquid 6 subsequently flows back into the wash tank 4. A discharge line 3 with a discharge pump 11 can be connected to the lower end 5 of the wash tank for the purpose of emptying the wash tank 4, if the need arises.
In the embodiment, illustrated in FIG. 1, of the dishwasher 1 according to the invention, the intake side of a first rinse pump 12 is connected to an outlet 35 of a boiler 21. The boiler 21 furthermore has an inlet 22 which is connected to a fresh-water feed line 28 and via which either fresh water or fresh water with rinse aid metered into it is supplied to the boiler 21. In the boiler 21, the liquid (pure fresh water or fresh water with rinse aid metered into it) which is supplied via the inlet 22 is heated up in accordance with the stipulations of a process sequence. Via the first rinse pump 12, the intake side of which is connected to the boiler outlet 35, the rinse liquid which is heated up in the boiler 21 can be supplied, for example during a fresh-water rinse phase, via a rinse line system 15, 15 a to rinse nozzles 33 and 34, respectively. The rinse nozzles 33 and 34 are arranged in the treatment chamber 2 in order to spray the rinse liquid heated in the boiler 21 onto the wash ware in the treatment chamber 2. Of course, however, it is also conceivable for the boiler 21 to be supplied via the inlet 22 and the fresh-water feed line 28 with pure fresh water into which a rinse aid is metered after the fresh water has been heated in the boiler 21.
Furthermore, in the embodiment, illustrated in FIG. 1, of the dishwasher 1 according to the invention, a second rinse pump 13 is provided, the intake side of which is connected to a fresh-water tank 14 and the delivery side of which is connected to a rinse line system 15, 15 b. The rinse line system 15 b which extends from the delivery side of the second rinse pump 13, and the rinse line system 15 a which extends from the delivery side of the first rinse pump 12 merge into a common rinse line system 15. By means of the second rinse pump 13 which is connected to the fresh water tank 14, unheated rinse liquid can be conveyed to the rinse nozzles 33 and 34 arranged in the treatment chamber 2 in order to spray unheated rinse liquid onto the wash ware, if the need arises.
The fresh-water tank 14 has an inlet 37 which is connected to a fresh-water feed line 31. Either pure fresh water or fresh water with rinse aid metered into it is supplied via this fresh-water feed line 31 to the fresh-water tank 14. Of course, however, it is also conceivable to arrange, downstream of the outlet 36 of the fresh-water tank 14, a metering device, not illustrated in FIG. 1, for the metering in of rinse aid.
The wash nozzles 7, 9 and the rinse nozzles 33, 34 are respectively preferably arranged above and below the wash ware region and directed towards the wash ware region of the treatment chamber 2. In the embodiment, illustrated in FIG. 1, of the dishwasher 1 according to the invention, an upper wash-nozzle system and an upper rinse-nozzle system formed separately therefrom, and a lower wash-nozzle system and a lower rinse-nozzle system formed separately therefrom are provided. Of course, however, it would also be conceivable to provide an upper and a lower wash-nozzle system which together serve to spray wash liquid and to spray rinse liquid. Instead of being arranged at the bottom and top, the wash nozzles 7, 9 and/or the rinse nozzles 33, 34 may also be arranged only at the top or only at the bottom, or instead or in addition, also on one side of the treatment chamber 2 and directed into the wash ware region transversely with respect to the treatment chamber 2.
In the embodiment, illustrated in FIG. 1, of the dishwasher 1 according to the invention, both the boiler 21 and the fresh-water tank 14 are connected via fresh- water feed lines 24, 26, 28, 29 and 31 to a return-prevention means 16. The return-prevention means 16 serves to prevent fresh water from being able to sucked back into a fresh-water feed line 17 from the intake side of the first rinse pump 12 and/or from the intake side of the second rinse pump 13.
The return-prevention means 16 has an outlet 40 which is connected via fresh- water feed lines 24 and 41 to a water-softening device 39. The water-softening device 39 has, firstly, a salt container 42 which is connected to the fresh-water feed line 41 and, secondly, first and second water softeners 39 a, 39 b which are arranged parallel to each other. The two water softeners 39 a, 39 b which are arranged parallel to each other are connected via a corresponding fresh-water line system and the fresh-water feed line 24 to the outlet 40 of the return-prevention means 16. The water softeners 39 a, 39 b of the water-softening device 39 can be operated alternately by suitable activation of the valves 43, in order to soften the fresh water supplied to the boiler 21 via the fresh- water feed lines 26 and 28 and to soften the fresh water supplied to the fresh-water tank 14 via the fresh- water feed lines 26, 29 and 31.
The salt container 42 belonging to the water-softening device 39 contains a suitable salt or a suitable chemical with which, when the need arises, a water-softening agent metered in via the water softeners 39 a and 39 b or a decomposition product produced when a water-softening agent is metered in can be suitably regenerated. The salt container 42 can be topped up with the salt or the chemical from the treatment chamber 2 of the dishwasher 1 via an opening which can be closed by a cover 44.
In the illustrated and preferred embodiment of the dishwasher 1 according to the invention, the boiler 21 has an integrated steam generator 20. A corresponding steam outlet 23 of the steam generator 20 is formed on the upper region of the boiler 21. The steam outlet 23 of the steam generator 20 is connected via a steam line 32 to the treatment chamber 2 at a location 37 above the wash tank 4 in order, when the need arises, to conduct the steam generated in the steam generator 20 into said treatment chamber. The outlet opening of the steam line 32 is preferably located between the upper nozzles 7, 33 and the lower nozzles 9, 34 of the wash line system 10 and of the rinse line system 15. Of course, however, other positions are also possible.
The boiler 21, which serves not only to heat the rinse liquid but also to generate steam, contains a heater 45. Furthermore, a level sensor 46 which controls, for example, a valve 19 of the fresh-water line 17 may be arranged in or on the boiler.
In the preferred embodiment, illustrated in FIG. 1, of the dishwasher 1 according to the invention, it is optionally possible, by means of the provision of the fresh-water tank 14 and the second rinse pump 13, also to supply non-heated rinse liquid via the rinse line system 15 b and 15 to the rinse nozzles 33 and 34, respectively. Accordingly, it is possible, by means of suitable activation, for example of the rinse pumps 12, 13, and/or by means of suitable activation, for example of the valves 19, 27 and 30 arranged in the fresh-water feed lines to the fresh-water tank 14 and the boiler 21, to supply non-heated or heated rinse liquid to the treatment chamber 2.
A program-control device 50 for controlling at least one cleaning program is designed in such a manner and is connected to the controllable components of the dishwasher, for example to the valves 19, 27 and 30, to the wash pump 8, to the first rinse pump 12, to the second rinse pump 13, and/or to a heater control circuit for controlling the heater 45, in order to realize a cleaning method (cleaning cycle) with the following steps (phases) to be executed successively:

- 1. A wash phase, in which wash liquid is sprayed from the wash tank 4 by means of the wash pump 8 through the wash line system 10 into the treatment chamber 2 and can then flow back into the wash tank 4 from the treatment chamber 2 because of the force of gravity;
- 2. A fresh-water rinse phase, in which heated or unheated fresh water or fresh water with rinse aid metered into it, as the rinse liquid, is sprayed by means of the first rinse pump 12 and the second rinse pump 13 into the treatment chamber 2 and can then flow into the wash tank 4 from the treatment chamber 2 because of the force of gravity; and
- 3. A steam rinse phase, which follows the fresh-water rinse phase and in which steam generated by the steam generator 20 is introduced into the treatment chamber 2 via the steam line 32, which is formed separately from the wash line system 10 and separately from the rinse line system 15.

Furthermore, the program controller 50 is preferably designed in such a manner that a condensation and draining phase is executed for a specific period of time in a program-controlled manner following the steam rinse phase, during which period of time steam introduced into the treatment chamber 2 during the steam rinse phase can condense and can drain from the treatment chamber 2 into the wash tank 4, before the end of the program is reached.
FIG. 2 schematically provides a dishwasher, in particular a commercial dishwasher, in the form of a program-controlled ware washer according to the second preferred embodiment of the solution according to the invention. In contrast to the first embodiment illustrated in FIG. 1, the dishwasher 1 illustrated in FIG. 2 does not have a fresh-water tank and therefore also does not have a second rinse pump via which—as illustrated in FIG. 1—unheated rinse liquid can be supplied via a rinse line system to the rinse nozzle. Otherwise, the dishwasher 1 illustrated in FIG. 2 is identical in a structural and functional regard with the dishwasher described previously with reference to FIG. 1.
Of course, it is conceivable that the heater control circuit (not illustrated explicitly) can correspondingly activate the heater 45 of the boiler 21 or of the steam generator 20 in order to provide rinse liquid which is heated to a greater or lesser extent.
The invention is not restricted to the embodiments of the dishwasher 1 that are shown by way of example in the drawings. On the contrary, the invention arises from an expert overall consideration of the patent claims and the description of the exemplary embodiments.

Claims

1. Method for cleaning wash ware in a program-controlled ware washer having a treatment chamber (2) for accommodating the wash ware to be cleaned, wherein the method has the following program-controlled method steps to be executed successively:

a wash phase, in which wash liquid (6) is sprayed from a tank (4) by means of a wash pump (8) through a wash line system (10) into the treatment chamber (2) and can flow back into the tank (4) from the treatment chamber (2) because of the force of gravity; and

a rinse phase, in which rinse fluid is conducted into the treatment chamber (2), characterized in that the rinse phase is composed of a fresh-water rinse phase, in which a rinse liquid is sprayed from a rinse-liquid supply device (14, 21) by means of a rinse pump (12, 13) through a rinse line system (15) into the treatment chamber (2) and can flow from the treatment chamber (2) into the tank (4) because of the force of gravity, and of a steam rinse phase, in which steam is generated by means of a steam generator (20), which is connected to a fresh-water feed line (28), and is conducted into the treatment chamber (2), with a total of 0.5 to 2.0 litres of rinse liquid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber (2) in a top view of the treatment chamber, being sprayed into the treatment chamber (2) during the fresh-water rinse phase.

2. Method according to claim 1, characterized in that a total water quantity of 0.05 to 0.25 litre per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber (2) in a top view of the treatment chamber, is conducted in steam form during the steam rinse phase into the treatment chamber (2).

3. Method according to claim 2, characterized in that 1.0 to 1.7 litres of rinse liquid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber (2) in the top view of the treatment chamber is sprayed into the treatment chamber (2) during the fresh-water rinse phase and water quantity of 0.10 to 0.15 litres per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber (2) in the top view of the treatment chamber is conducted in steam form during the steam rinse phase into the treatment chamber (2).

4. Method according to claim 1, characterized in that the steam rinse phase takes up a period of time of 5 to 60 seconds.

5. Method according to claim 1, characterized in that the steam rinse phase begins after the fresh-water rinse phase ends.

6. Method according to claim 1, characterized in that the steam rinse phase and the fresh-water rinse phase at least partially overlap chronologically.

7. Method according to claim 1, characterized in that the method furthermore has a condensation and draining phase which is carried out following the steam rinse phase and lasts for a defined time, and in which the steam conducted into the treatment chamber (2) during the steam rinse phase can at least partially condense, drain and flow into the tank (4) because of the force of gravity.

8. Method according to claim 1, characterized in that clean fresh water is used as the rinse liquid during the fresh-water rinse phase, or in that fresh water and the rinse aid which is metered into the fresh water are used as the rinse liquid during the fresh-water rinse phase.

9. Method according to claim 1, characterized in that rinse liquid which is heated or unheated during the fresh-water rinse phase is sprayed into the treatment chamber (2).

10. (canceled)

11. Dishwasher (1) in the form of a program-controlled ware washer, having:

a program-control device (50) for executing at least one cleaning program;

a treatment chamber (2) into which wash ware can be manually inserted and from which said wash ware can be manually removed;

a tank (4) down into which liquid from the treatment chamber (2) can flow because of the force of gravity;

a wash system (7, 8, 9, 10) with a wash pump (8) and a wash line system (10) for conveying wash liquid (6) from the tank (4) through wash nozzles (7, 9) into the treatment chamber (2) during a wash phase;

a fresh-water rinse system (12, 13, 15 a, 15 b, 33, 34) with at least one rinse pump (12, 13) and at least one rinse line system (15 a, 15 b) for conveying rinse liquid from a fresh-water supply device (14, 21) through rinse nozzles (33, 34) into the treatment chamber (2) during a fresh-water rinse phase; and

a steam rinse system (20, 32) with a steam generator (20), which is connected to a fresh-water feed line (28), for generating steam and conducting the steam via a steam line (32) into the treatment chamber (2) during a steam rinse phase,

wherein the program-control device (50) is designed in such a manner that first the wash phase, then the fresh-water rinse phase and thereafter the steam rinse phase are executed,

characterized in that the program-control device (50) and the fresh-water rinse system (12, 13, 15 a, 15 b, 33, 34) controlled by it are designed to spray a total of 0.5 to 2.0 litres of rinse liquid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber (2) in a top view of the treatment chamber, into the treatment chamber (2) during the fresh-water rinse phase.

12. Dishwasher according to claim 11, characterized in that the program-control device (50) and the steam rinse system (20, 32) controlled by it are designed to conduct a total water quantity of 0.05 to 0.25 litre per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber (2) in a top view of the treatment chamber, in steam form into the treatment chamber (2) during the steam rinse phase.

13. Dishwasher according to claim 12, characterized in that 1.0 to 1.7 litres of rinse liquid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber (2) in the top view of the treatment chamber is sprayed into the treatment chamber (2) during the fresh-water rinse phase and water quantity of 0.10 to 0.15 litres per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber (2) in the top view of the treatment chamber is conducted in steam form during the steam rinse phase into the treatment chamber (2).

14. Dishwasher according to claim 11, characterized in that the treatment chamber (2) is designed to accommodate at least one basket of 500 mm×500 mm.

15. Dishwasher according to claim 11, characterized in that the fresh-water supply device (21) for heating the rinse liquid to be conveyed into the treatment chamber (2) during the fresh-water rinse phase has a boiler (21) which is connected to a fresh-water feed line (28) and the outlet (35) of which is connected to the intake side of a first rinse pump (12), of which there is at least one.

16. Dishwasher according to claim 11, characterized in that the fresh-water supply device (14) has a fresh-water tank (14) which is connected to a fresh-water line (31) and the outlet (36) of which is connected to the intake side of a second rinse pump (13), of which there is at least one.

17. Dishwasher according to claim 11, characterized in that the steam generator (20) is integrated in the boiler (21); and a steam outlet (23) of the steam generator (20) is connected to the treatment chamber (2) via a steam line (32), which is separate from the rinse line system (15) and the wash line system (10), at a location (37) which is higher than the tank (4).

18. (canceled)

19. Dishwasher according to claim 11, characterized in that the program-control device (50) is designed to execute a condensation and draining phase which follows the steam rinse phase and which lasts for a defined time during which steam which has condensed in the treatment chamber (2) can flow down into the tank (4) after the steam rinse phase, before the end of the program is reached.

20. Dishwasher according to claim 11, characterized in that a rinse-aid metering device is provided for metering rinse aid into the fresh water of the rinse liquid.

21. Dishwasher according to claim 11, characterized by a return-prevention means (16) via which the intake end of the at least one rinse pump (12, 13) is connected to a fresh-water feed line (17), with the back flow-prevention means (16) being designed to prevent liquid from flowing back into the fresh-water feed line (17) in the direction from the at least one rinse pump (12, 13).

22. Dishwasher according to claim 11, characterized by a water-softening device (39) for conditioning the fresh water for the fresh-water rinse system (12, 13, 15 a, 15 b, 33, 34) and the fresh water for the steam rinse system (20, 32).