EP2756788A2

EP2756788A2 - Dish washing method

Info

Publication number: EP2756788A2
Application number: EP20130199631
Authority: EP
Inventors: Silvia Barus; Gianluca Benedetto; Marco Ten Bok
Original assignee: Indesit Co SpA
Current assignee: Whirlpool EMEA SpA
Priority date: 2012-12-28
Filing date: 2013-12-27
Publication date: 2014-07-23
Anticipated expiration: 2033-12-27
Also published as: EP2756788B1; EP2939585B1; EP2949256A1; EP2949256B1; EP2939585A1; EP2756788A3

Abstract

A dish washing method, comprising the steps of: distributing washing water to at least one impeller (29) arranged above a rack (39) for containing dishes; and generating through the impeller (29) a jet of water (69a-69c) directed at a predefined area (79a-79c) of the rack (39) to hit the dishes with said water; said step of distributing the water being actuated by supplying the water to the impeller (29) according to a plurality of predefined values each of which represents a different area (79a-79c) subtended by a respective jet (69a-69c) dispensed from the impeller (29).

Description

The present invention relates to a dish washing method. The washing method is in particular implemented by a dishwasher equipped preferably with a spraying device of rotating type generally arranged on the top of the dishwasher to dispense a jet falling downwards.
As is known, sprayers of this type consist of an impeller mounted idly to generate a jet with an umbrella profile which hits a predefined area of a rack containing dishes.
Besides the action of the impeller, the dishwasher comprises furthermore dispensers on rotating arms, arranged below respective racks to hit the dishes from below.
Generally, dishwashers are known equipped with three racks, arranged one above the other. Such dishwashers have a lower dispenser arranged below the lowest rack, and an upper dispenser arranged below the middle rack. The dishes contained in the upper rack however are washed principally by the umbrella jet generated by the upper impeller.
The known dishwashers comprise furthermore a supply pump, generally a centrifugal pump to feed the washing water alternately and sequentially to the dispensers or to the impeller.
The amplitude of the umbrella jet, and therefore also the corresponding area of the rack which is hit by the jet, is determined by the speed and flow rate of the water fed by the pump. In particular, depending on the revolutions per minute of the centrifugal pump, the dispensers and the impeller are made to rotate at a predetermined speed. In the case of the impeller, this rotation speed determines the respective umbrella jet of water.
The water supply to the dispensers and to the impeller is effected according to a predefined programme in which washing cycles alternate with loading/unloading the water inside the dishwasher. The washing cycles comprise sequential steps of supplying water to at least one of the dispensers and/or to the impeller, according to predefined periods, in order to be able to wash all the dishes arranged in the racks. Furthermore, the washing cycles are performed at predetermined temperatures such that the water while it is being dispensed can be heated to reach a particular temperature or maintained at a constant temperature.
The Applicant has found that the washing methods used by the dishwashers described above can be improved from the point of view of efficiency in the washing steps of the upper rack.
In fact, unlike rotating arm dispensers which during their movement hit the entire area of the respective upper racks, the impeller of the upper sprayer generates an umbrella jet which hits only a predefined circular area of the rack.
In this context, the most central area of the rack and the outermost peripheral area are not affected by the jet of water.
Consequently, some dishes arranged in the areas not affected by the jet of water generated by the impeller are not washed correctly by the aforesaid umbrella jet.
An object of the present invention is therefore to make available a method of washing dishes which overcomes the drawback of the known art mentioned above.
In particular, it is an object of the present invention to make available a method of washing dishes which is capable of spraying all the areas of the upper rack so as to completely wash all the dishes positioned in this rack. It is furthermore an object of the invention to make available a method of washing dishes which is versatile and capable of being adapted to the various process requirements.
The objects set forth above, and yet others, are fully achieved by the washing method according to the present invention, which is characterised by what is contained in the claims set forth below.
The technical characteristics of the invention, according to the aforementioned object, can be clearly seen from the contents of the claims set forth below, and the advantages thereof will more fully emerge from the detailed description which follows, made with reference to the accompanying drawings, which represent a purely exemplary and non-limiting embodiment, wherein:

figure 1 shows a schematic side view of a hydraulic circuit of a dishwasher by means of which the method according to the present invention is implemented;
figure 2 shows a graph which has on the vertical axis a qualitative scale of the temperature and on the horizontal axis the time relating to a washing cycle using the method which is the subject of the present invention.

Unless explicitly stated to the contrary, reference is made to figures 1 and 2. With reference to figure 1, the dish washing method is preferably implemented by a dishwasher 19 equipped with at least one impeller 29 arranged above a respective upper rack 39 containing dishes. The impeller 29 is mounted idly within the compartment 59 which defines the dishwasher 19, in such a way as to rotate following the supplying of the washing water.
The method comprises the steps of distributing the washing water to at least the impeller 29 in such a way that a jet 69 of water is generated, directed into a predefined area of the upper rack 39.
In particular, the step of distributing the water to the impeller 29 is actuated by supplying water according to a plurality of predefined values each of which represents a different area 79a-79c subtended by a respective jet 69a-69b dispensed by the impeller 29.
In particular, the distribution of the water is actuated by means of a pump 49, configured to supply the washing water at the predefined values corresponding to the pressure and the flow rate of the water.
Advantageously, the pump 49 is of centrifugal type and the predefined values for supplying the water are therefore defined by a series of values of speed of rotation of the aforementioned pump 49 located upstream of the impeller 29.
Consequently, for each predefined rotation value of the pump 49 a respective jet 69a-69b is generated having a substantially umbrella profile and capable of affecting a corresponding area 79a-79c.
With reference to figure 1, only three water jets 69a-69c have been shown by way of example, generated by three respective predefined values, to wash three areas 79a-79c of the dishwasher. It must however be specified that there can be any number of predefined values for washing any area of the rack and therefore all the dishes contained therein.
The amplitude of the jet 69a-69b of water is therefore linked to the speed of rotation of the pump 49. In other words, the greater the speed of rotation of the pump 49, the greater is the area 79 washed by the jet 69.
For example, at a speed of rotation of the pump 49 comprised between 1600 and 2000 rpm, the jet of water 6a is generated which hits the most central area 79a of the rack 39.
At a speed of rotation of the pump 49 comprised between 2100 and 2500 rpm the jet of water 6b is generated which hits the most peripheral area 79b of the rack 39.
At high rotation speed of the pump 49, for example a speed comprised between 2500 and 2800 rpm, on the other hand, corresponds to the jet 69c which is directed onto the outermost part of the dishwasher 19 and therefore onto the inner walls 89 of the compartment 59.
It should be noted that the above-mentioned predefined values are determined according to the type of washing and the various method requirements. This setting is actuated by suitable management software (not described and illustrated because it does not form part of the present invention) for the rotation speeds of the pump 49.
Again, each predefined value for supplying the water to the impeller 29 corresponds to a respective period of time for which that value is maintained. In this way, the individual jets 69a-69c are maintained according to a predefined period of time.
It should be noted furthermore that the speed of rotation of the pump 49 can accelerate/decelerate progressively in a predefined period, in such a way that during the change between one value and another, a progressive enlargement/contraction is produced of the area subtended by the water jets generated.
Furthermore, the water dispensing values, as well as the duration of each individual value, can be actuated at predetermined temperatures. Consequently, the water can be dispensed by the impeller, according to the alternation of the above-mentioned predefined values, heating the water to a predetermined temperature or maintaining the water at a constant temperature.
Alternating the above-mentioned water dispensing values by means of the umbrella jets 69a-69c defines a unique washing cycle in which the dishes are washed and rinsed for a series of steps in succession.
Within the washing cycle, one or more steps are alternated of loading and unloading the washing water into the containment compartment 59.
Furthermore, the washing cycle comprises one or more steps of dispensing washing water below the rack 39 by means of at least one rotating arm 99 positioned below the rack 39 itself.
In particular, it should be noted that the dishwasher can be equipped with a plurality of racks, for example three racks 39, arranged one above the other. Below the lower rack 39 a lower arm 99 extends which dispenses water from below towards this rack.
Below the middle rack 39 an upper arm 99 extends which dispenses water from below towards this rack 39. The upper rack 39, onto which the jet 69a-69b of water is dispensed from the impeller 29, is arranged above the middle rack 39.
By way of example, a cycle is described below of washing the dishes contained inside the dishwasher 19 summarily described above.
The washing cycle is described below with reference to the graph shown in figure 2.
In particular, in the graph of figure 2 the duration of the steps in minutes is shown along the horizontal axis, and the temperature of the water is shown on the vertical axis.
The reference number 109 indicates an initial step of loading the containment compartment 59 with washing water.
Subsequently, the washing step indicated with the reference number 119 is shown.
Within this step water is dispensed to the dishes through at least two rotating arms 99 and through at least the impeller 29 positioned above the upper rack.
This step is performed alternately to dispense water first from the arm 99 positioned below the lower rack 39, then to the arm 99 positioned below the middle rack 39 and to the impeller 29.
More particularly, the step of washing 119 comprises the sub-step 129 of keeping cold wherein the rotating arms 99 are supplied with water at a speed of the pump 49 comprised between 2200 and 2800 rpm, while the impeller 29 is supplied with a rotation speed of the pump 49 at a value comprised between 2100 and 2500 rpm. This dispensing is effected by performing an alternation (with a duration of each alternation comprised between 1 and 5 minutes) which affects each arm 99 and the impeller 29. The set of said alternations concerns a period of duration comprised between 10 and 20 minutes. Furthermore, the step of keeping cold 129 is actuated at the water network temperature.
Subsequently there begins the sub-step 139 of ramping up the heating wherein the rotating arms 99 are supplied with water at a speed of the pump 49 comprised between 2300 and 2700 rpm, while the impeller 29 is supplied at three predefined speeds corresponding to the aforementioned predefined values. In fact, the impeller 29 is supplied first with water at the speed value of the pump 49 comprised between 2100 and 2500 rpm, subsequently at a speed value of the pump 49 comprised between 1600 and 2000 rpm and subsequently at a speed value of the pump comprised between 2100 and 2500 rpm. This dispensing is effected by performing an alternation (with a duration of each alternation comprised between 1 and 5 minutes) which affects each arm 99 and the impeller 29. The set of said alternations concerns a period of duration comprised between 10 and 20 minutes. For the impeller 29 the predefined values each last for a period comprised between 30 and 55 sec.
Furthermore, the step 139 is effected by heating the water until it reaches a temperature comprised between 45 °C and 50 °C.
Subsequently, there is effected the sub-step 149 of keeping hot. In this step the water temperature is kept constant in a range comprised between 45 °C and 50 °C.
Opportunely during sub-step 149 the rotating arms 99 are supplied with water at a speed of the pump 49 comprised between 2300 and 2700 rpm, while the impeller is supplied by making the pump 49 rotate at a speed comprised between 1700 and 2800 rpm. This dispensing is effected by performing an alternation (with a duration of each alternation comprised between 1 and 5 minutes) which affects each arm 99 and the impeller 29. In this step the water temperature diminishes as a result of thermal dissipation.
At the end of the step of delivering the water (washing step 119) a step 169 is effected of unloading the water from the containment compartment 59, and subsequently the compartment 59 is loaded for a second time with clean washing water.
At this point, the water is dispensed for a second time from the arms 99 and from the impeller 29 for a cold rinsing operation. This operation is effected by a maintaining sub-step 179 in which the rotating arms 99 are supplied with water at a speed of the pump 49 comprised between 2300 and 2700 rpm, while the impeller is supplied at a speed of the pump comprised between 2100 and 2500 rpm. This dispensing is effected by performing an alternation (with a duration of each alternation comprised between 1 and 5 minutes) which affects each arm 99 and the impeller 29.
Subsequently the step 189 is effected of unloading the water for a second time from the containment compartment 59. At this point the compartment 59 is loaded for a third time with clean washing water.
In this way, the water is dispensed for a third time for a hot rinsing operation 199.
Advantageously, in the example of the washing cycle described above the impeller is supplied according to a plurality of predefined values, each of which represents a different area subtended by a respective jet dispensed by the impeller. In fact, in the sub-step 139 of ramping up the heating and keeping hot 149, the speed is varied of supplying the pump 49, with the consequent variation in the amplitude of the jets 69a-69c and of the area 79a-79c which is washed.
All the areas of the upper rack are therefore sprayed to completely wash all the dishes positioned within it. Furthermore, by modifying the water jet 69 it is possible to adapt the washing and rinsing operations to the various operative requirements, in terms both of washing cycle and of positioning the dishes in the rack.
It should be noted furthermore that at high speeds of rotation of the pump 49 (for example for a speed of rotation comprised between 2500 and 2800 rpm), the impeller 29 generates a jet of water 69c directed against the internal walls 89 with the consequent advantageous operation of washing the walls of the compartment 59.
Please refer in what follows to figures 3-7 only.

figure 3 shows an open dishwasher (i.e. in which the door has been removed), according to the present invention, in a side view;
figure 4 shows several components (spraying means) of the dishwasher of figure 3, in a side view;
figure 5 shows several components (top spraying means) of the dishwasher of figure 3, in perspective view;
figure 6 shows several components (sprinkler) of the dishwasher of figure 3, in an exploded perspective view;
figure 7 shows the qualitative progress of the temperature as a function of time (along the horizontal axis) relating to the ECO programme of the dishwasher of figure 3.

With reference to the drawings, no. 1 indicates a dishwasher comprising a box-shaped casing 2, substantially in the shape of a parallelepiped, defining a washing compartment 3. Inside the washing compartment 3 are two racks 4, 5 destined for housing the dishes to be washed.
In particular, the following can be distinguished:

a lower rack 4 slidable on a pair of rails (not shown) positioned in proximity to the bottom 2a of the box-shaped casing 2;
an upper rack 5 positioned above the lower rack 4 and slidable on a pair of rails (not shown) positioned on lateral walls 2b, 2c of the box-shaped casing 2.

These racks 4, 5 are the only racks present in the dishwasher 1. In particular the expression 'racks' in the course of this treatment is intended to mean support means for the dishes to be washed which slide along guides formed along the box-shaped casing 2. Opportunely these racks are perforated, being obtained by intersection of filiform elements. They have overall dimensions which almost completely occupy a horizontal level of the box-shaped casing 2. Any accessories applicable to said racks to increase their load capacity or make them suitable for housing particular types of dishes (for example tiltable flaps or cutlery containers) are to be considered an integral part of said racks and are not to be considered distinct racks.
The dishwasher 1 comprises spraying means 6, 7, 8 arranged inside the washing compartment 3 and capable of spraying washing liquid on the dishes contained in the two racks 4, 5. In particular, the washing liquid comprises water and detergents (cleaning agents, finisher etc.). After coming into contact with the dishes to be washed, the washing liquid also comprises the dirt removed from the dishes to be washed (for example residues of food or condiments).
The dishwasher 1 comprises furthermore conveying means 9 suitable for connecting the washing compartment 3 to the spraying means 6, 7, 8. Preferably, the conveying means 9 connect the bottom 2a of the box-shaped casing 2 to the spraying means 6, 7, 8. The dishwasher 1 comprises a motorised pump 10 operatively active on the conveying means 9 to take the washing liquid from the washing compartment 3 and send it to the spraying means 6, 7, 8.
The washing liquid sprayed by the spraying means 6, 7, 8 builds up by gravity on the bottom 2a of the box-shaped casing 2, where it is picked up by the motorised pump 10 and sent again to the spraying means 6, 7, 8 via the conveying means.
The spraying means 6, 7, 8 comprise first bottom spraying means 6, second bottom spraying means 7 and top spraying means 8. The first bottom spraying means 6 are situated below the lower rack 4. The first bottom spraying means 7 are situated below the upper rack 5. The top spraying means 8 are positioned above the upper rack 5.
Preferably, the top spraying means 8 consist of a sprinkler comprising an impeller 12, a ring nut 13 and a cage 14 attachable to the ring 13 in such a way as to form a housing receptacle 15 for the impeller 12.
The cage 14 has a pin 16 having an end 16a of conical shape. The impeller 12 has a through hole 17 in such a way as to be able to be rotatably mounted on the pin 16 of the cage 14.
During the rotation of the impeller 12 around the pin 16, the flow of washing liquid diverges ("umbrella" opening).
Preferably, the sprinkler 8 is attached to the conveying means 9 by rotation of the ring nut 13 through a quarter of a turn.
The dishwasher 1 comprises a selector 11 operatively active over the conveying means 9 to selectively open a first route 9a towards the first bottom spraying means 6 or a second route 9b towards the second bottom spraying means 7 or a third route 9c towards the top spraying means 8 in such a way that the washing liquid is sprayed from the selected sprayer.
In the event of opening of the first route 9a or the second route 9b, the motorised pump 10 operates at a rotation speed comprised between 2300 and 2600 revolutions per minute.
In the event of opening of the third route 9c, the motorised pump 10 operates at between 1500 and 2500 revolutions per minute.
As will be better explained below, the selector 11 is formed of a fixed disc and a rotating disc superimposed.
The procedure for washing dishes placed in a washing compartment housing only two racks is described below.
This method is used both in ECO washing programmes (or cycles) and in normal programmes (i.e. non-ECO). Preferably, the proposed procedure is used for washing dishes positioned in the racks 4, 5 in such a way as to have the concavity facing downwards.
This procedure provides for the following steps:

setting a bottom spraying of the lower rack 4 through the first bottom spraying means 6;
setting a bottom spraying of the upper rack 5 via the second bottom spraying means 7;
acting on the selector 11 to switch the supply of the washing liquid at least between a first conduit 9a which supplies the first spraying means 6 and a second conduit 9b which supplies the second spraying means 7;

Opportunely the method comprises a first step of setting a top spraying of said upper rack 5 via the top spraying means 8 positioned above said upper rack 5 and supplied via the third conduit 9c. The third conduit 9c connects the spraying means 8 to said selector 11. The step of setting a top spraying of said upper rack 5 comprises a step of removing the dirt built up in said third conduit 9c during the change from spraying the lower rack 4 to spraying the upper rack 5 or vice versa. In fact the selector 11 comprises a fixed disc comprising at least one hole and a movable disc comprising a plurality of holes. Depending on which hole in the movable disc is superimposed on the hole in the fixed disc, the first or second or third conduit 9a, 9b, 9c is supplied. To switch the flow from the first to the second conduit 9a, 9b or vice versa, the movable disc rotates and during this rotation the hole in the fixed disc is superimposed for a brief space of time on the hole which supplies the third conduit 9c, causing the introduction of a small quantity of water (often dirty) which stagnates in the third conduit 9c.
Bottom spraying of the lower rack 4 and bottom spraying of the upper rack 5 are carried out alternately several consecutive times in such a way as to form a step of bottom spraying.
The step of removing the dirt built up in the third conduit 9c is performed before and/or after this step of bottom washing. In particular it is performed at the end of a ramping up of the heating of the washing liquid. It can also be performed after a long step (for example greater than 30 minutes) in which said step of bottom washing is performed).
The duration of the step of bottom washing is greater by an order of magnitude than the duration of the step of removing the dirt built up in the third conduit 9c.
Preferably, both the bottom spraying of the lower rack 4 and the bottom spraying of the upper rack 5 have a duration comprised between about one minute and about five minutes, while the bottom washing (which is given by the multiple alternation of these sprayings) has a duration comprised between about twelve minutes and fifty-six minutes.
The step of removing the dirt built up in the third conduit 9c has a duration comprised between about one minute and about five minutes.
The embodiment here described and illustrated refers to a programme or cycle of ECO type thus composed.
The washing liquid is loaded into the washing compartment 3 during a first loading step.
Subsequently, the step of bottom washing is actuated for a duration comprised between 25 and 40 minutes during which the temperature of the washing liquid is kept constant between 20 and 25 °C for a first interval comprised between 10 and 20 minutes (see reference "a" in figure 7) and is heated up to a temperature comprised between 45° and 55°C in a second interval of duration comprised between 10 and 20 minutes (see reference "b" in figure 7).
There follows the step of removing the dirt built up in the third conduit 9c, having a duration comprised between 1 and 5 minutes (see reference "c" in figure 7).
Subsequently, the step of bottom washing is performed again for a total duration comprised between 50 and 60 minutes during which the temperature of the washing liquid is kept constant (see reference "d" in figure 7). There follows the step of removing the dirt built up in the third conduit 9c, having a duration comprised between 1 and 5 minutes (see reference "e" in figure 7).
The succession of steps of bottom washing for the first time, removing the dirt from the third conduit for the first time, bottom washing for the second time and removing the dirt from the third conduit for the second time constitute the so-called ECO cycle "wash".
The ECO cycle comprises furthermore the so-called "cold rinsing" (see reference "f") and the so-called "hot rinsing" (see reference "g"), which are not explained in detail because they do not constitute the subject of the patent.
In alternative embodiments, the step of removing the dirt from the main conduit can be performed even during the "cold rinsing" or during the "hot rinsing".
From the description given the characteristics are clear of the dishwasher and of the method for washing dishes placed in a washing compartment housing only two racks, according to the present invention, and the advantages are also clear.
In particular, the problem of the build-up of dirt, due to momentary undesired selections of the holes by the selector, is resolved thanks to the activation of the top spraying means (sprinkler).
Furthermore, activating the sprinkler at the end of the ramping-up of the heating exploits the descaling power of heat.
Furthermore, good cleaning of the main conduit is achieved by activating the sprinkler even after the last step of bottom washing, which is very long and therefore entails a considerable build-up of dirt in the conduit itself.
Since the activation of the sprinkler occurs for brief periods compared with the activation of the bottom spraying means (there is a difference of an order of magnitude), the dirt introduced by the activation of the sprinkler is negligible.
Furthermore, being positioned above the upper rack, the sprinkler makes it possible to complete the washing of the dishes by spraying from above (the other sprayers are positioned below the relative racks).
The technical task stated and the specified object are substantially achieved by a dishwasher and a procedure for washing dishes positioned in a washing compartment, comprising the technical characteristics set forth in one or more of claims 11 to 15.

Claims

A dish washing method, comprising the steps of:
- distributing washing water to at least one impeller (29) arranged above a dish containment rack (39); and

- generating through the impeller (29) a jet of water (69a-69c) directed towards a predefined area (79a-79c) of the rack (39) to hit the dishes with said water;
characterised in that said step of distributing the water is actuated by supplying water to the impeller (29) according to a plurality of predefined values each of which represents a different area (79a-79c) subtended by a respective jet (69a-69c) dispensed by the impeller (29).
The method according to the preceding claim, characterised in that each predefined value of water supply to the impeller (29) corresponds to a respective period of time for that value.
The method according to any of the preceding claims, characterised in that the supply of the water to the impeller (29) according to a plurality of predefined values determines a progressive enlargement/contraction of the area (79a-79c) subtended by the jets (69a-69c) of water.
The method according to any one of the preceding claims, characterised in that said step of distributing water to the impeller (29) is actuated by a pump (49); said predefined water supply values corresponding to water pressure and flow rate values at the outlet from said pump (49).
The method according to any of the preceding claims, characterised in that said predefined water supply values are defined by the speed of rotation of a centrifugal pump (49) positioned upstream of the impeller (29).
The method according to the preceding claim, characterised in that said water supply values correspond at least to:
a speed of rotation of the pump (49) comprised between 1600 and 2000 rpm to generate a jet of water (69a) that hits a substantially central area (79a) of the rack (39);

a speed of rotation of the pump (49) comprised between 2100 and 2500 rpm to generate a jet of water (69b) that hits a substantially peripheral area (79b) of the rack (39); and

a speed of rotation of the pump (49) comprised between 1400 and 2800 rpm to generate a jet of water (69c) that hits the lateral walls (89) of a containment compartment (59) of the rack (39).
The method according to claim 5 or 6, characterised in that within a washing cycle said predefined water supply values are alternated corresponding to the different speeds of rotation of the centrifugal pump (49).
A dish washing cycle, comprising the steps of:
- loading with washing water a containment compartment (59) of at least three dish housing racks (39) positioned one on top of the other; then

- dispensing water to the dishes through at least two rotating arms (99) positioned below a lower rack (39) and a middle rack (39) respectively; and

- dispensing water to the dishes through at least one impeller (29) positioned above the upper rack (39);

- said steps of dispensing the water being actuated alternately to dispense water from the arm (99) positioned below the lower rack (39), from the arm (99) positioned below the middle rack (39) and from the impeller (29);

- said steps of dispensing the water being actuated for a determined period in which the water is initially dispensed at the water network temperature, then dispensed by heating it until a temperature comprised between 45 and 50 °C is reached, and then it is dispensed at a constant temperature in an interval comprised between 45 and 50 °C. characterised in that said steps of dispensing the water through the impeller comprise the operating steps described in any one of the preceding claims.
The cycle according to the preceding claim, characterised in that during the dispensing of the water, heating it from the network temperature to a temperature comprised between 45 and 50 °C, and during at least a part of the dispensing of the water at a constant temperature comprised between 45 and 50 °C, the predefined water supply values to the impeller (2) are alternated.
The cycle according to claim 8 or 9, characterised in that it further comprises, following the water dispensing step, the further steps of:
- unloading the water from the containment compartment (59);

- loading the containment compartment (59) with clean washing water a second time; then

- dispensing the water a second time alternately through the rotating arms (99) and through the impeller (29); then

- unloading the water from the containment compartment (59) a second time; then

- loading the containment compartment (59) with clean washing water a third time; and then

- dispensing the water to the dishes a third time.
The method for washing dishes placed in a washing compartment (2) housing only two racks (4, 5), comprising the steps of:
setting the bottom spraying of a lower rack (4) through first bottom spraying means (6);

setting the bottom spraying of an upper rack (5), positioned above said lower rack (4), through second bottom spraying means (7);

acting on a selector (11) to switch the supply of a washing liquid at least between a first conduit (9a) which supplies the first spraying means (6) and a second conduit (9b) which supplies the second spraying means (7);

characterised in that it comprises a step of setting the top spraying of said upper rack (5) through top spraying means (8) positioned above said upper rack (5) and supplied through a third conduit (9c) which connects them to said selector (11); the step of setting the top spraying of said upper rack (5) comprising a step of removing the dirt built up in said third conduit (9c) during the change from the spraying of the lower rack (4) to the spraying of the upper rack (5) or vice versa.
The method according to claim 11, wherein the step of setting the bottom spraying of the lower rack (4) and the step of setting the bottom spraying of the upper rack (5) alternate a few consecutive times so as to define a bottom washing step, said step of removing the dirt built up in the third conduit (9c) being performed at least after said bottom washing step.
A dishwasher (1) comprising:
a washing compartment (3);

a lower rack (4) and an upper rack (5) intended to house dishes, said upper rack (5) being positioned above the lower rack (4) within the washing compartment (3);

first bottom spraying means (6) arranged below the lower rack (4) so as to spray it with washing liquid;

second bottom spraying means (7) arranged below the upper rack (5) so as to spray it with washing liquid;

conveying means (9) suitable to connect the washing compartment (3) to said first and second spraying means (6, 7);

a motorised pump (10) operatively active on the conveying means (9) to take the washing liquid from the washing compartment (3) and send it to said first and second spraying means (6, 7),

characterised in that it comprises top spraying means (8) pertaining to said conveying means (9) and positioned above the upper rack (5) so as to spray it with the washing liquid for durations shorter by an order of magnitude than the spraying durations from said first and second spraying means (6, 7), said racks (4, 5) being the only racks present in the dishwasher (1).
The dishwasher (1) according to claim 13, further comprising a selector (11) operatively active on the conveying means (9) to selectively open a first conduit (9a) towards said first bottom spraying means (6) or a second conduit (9b) towards said second bottom spraying means (7) or a third conduit (9c) towards said top spraying means (8), said motorised pump (10) operating at between 1500 and 2500 revolutions per minute in the event that said third conduit (9c) opens.
The dishwasher (1) according to claim 13 or 14, wherein said top spraying means (8) consist of a sprinkler comprising an impeller (12), a ring nut (13) and a cage (14) to be coupled to said ring nut (13) so as to define a housing receptacle (15) for said impeller (12).