EP2378944A1

EP2378944A1 - Method for drying crockery in a dishwasher and dishwasher using said method

Info

Publication number: EP2378944A1
Application number: EP09805860A
Authority: EP
Inventors: Marco Whilhelmus Gerhardus Ten Bok
Original assignee: Indesit Co SpA
Current assignee: Whirlpool EMEA SpA
Priority date: 2008-12-22
Filing date: 2009-12-15
Publication date: 2011-10-26
Anticipated expiration: 2029-12-15
Also published as: WO2010073185A1; EP2378944B1; ITTO20080970A1; IT1392563B1

Abstract

The present invention relates to a method for drying crockery housed in a tub (2) of a dishwasher (1), in which dishwasher (1) the crockery is subjected, in the course of a wash cycle, to the washing action of a wash liquid flow generated by water circulation means (11) and conveyed onto said crockery through a hydraulic circuit, comprising the step of generating an air flow through air circulation means and conveying the air flow into the tub (2) and onto the crockery, thus removing humidity therefrom, wherein the air circulation means coincide with the water circulation means (11).

Description

METHOD FOR DRYING CROCKERY IN A DISHWASHER AND DISHWASHER USING SAID METHOD

DESCRIPTION

The present invention relates to a method for drying crockery in a dishwasher, as well as to a dishwasher using said method.

Dishwashers are traditionally adapted to wash crockery, which for this purpose is housed in racks inside a tub and is sprayed with a wash liquid (normally water and detergent and/or rinse aid or the like) coming out of a rotary sprayer arranged near each rack. To this end, the wash liquid is moved by water circulation means, e.g. a pump, and flows through a hydraulic circuit that includes the tub, a pump intake duct, a sprayer supply duct and the sprayers themselves, then returning back into the tub; in the circuit, the wash liquid is heated by a suitable electric resistor in order to improve the washing action.

The need to include a dish drying cycle has arisen over time, for which purpose dishwashers have been conceived wherein the crockery removed by the user is already dry or just slightly damp. An example of such machines is described in international patent application WO 2005/060821 in the name of BSH BOSCH UND SIEMENS HAUSGERATE GMBH: in this dishwasher, air circulation means, such as a fan, and an air heating electric resistor have been added just for this purpose.

It can be noted that the air is supplied into the tub by using as outlets the distribution nozzles of the rotary sprayers, which are normally used (during the wash cycles) for spraying the wash liquid.

A first drawback of this machine is that it suffers from a certain construction complexity; in fact, in order to heat and convey the air towards the distribution nozzles of the rotary sprayers, it is necessary to employ a special circuit comprising air circulation means, e.g. a fan, and a dedicated electric resistor. It should also be noted that, in order to prevent damp air from getting into the outside environment, in this solution the air flows several times through the circuit that includes the tub, the fan and the resistor: the air, heated by the resistor, is conveyed by the fan into the tub and onto the crockery, thereby subtracting dampness therefrom; the air is then condensed onto the tub walls, the temperature of which must, for this purpose, be lower than the air temperature; to this end, said tub walls are essentially made out of metal plates placed in a condition of thermal exchange with the environment. This also implies that the machine operating parameters must be controlled accurately so as to ensure that the moisture contained in the air is condensed onto the tub walls: in fact, should the latter reach temperatures too close to that of the air, there would be insufficient condensation or no condensation at all.

In this regard, the drying efficiency of the machine in a very warm environment (such as the kitchen of a restaurant or in the summer season) might be adversely affected by a high outside temperature, thus increasing the energy consumption.

It is a first object of the present invention to provide a dishwasher which carries out a dish drying cycle while being extremely simple and effective.

It is another object of the present invention to disclose a method for drying crockery contained inside a tub of a dishwasher which is effective and which can provide an economical drying cycle independently of the conditions of the outside environment.

These and other objects are achieved by a method for drying crockery in a dishwasher and by a dishwasher using said method.

The present invention is based on the idea of using the very same pump normally included in the wash liquid hydraulic circuit also for blowing air onto the crockery in order to dry the latter.

According to an advantageous aspect, the air temperature is increased by means of the same electric resistor used for heating the wash liquid without needing a specific resistor, which is beneficial in terms of construction simplicity. A further advantageous aspect of the present invention is that the air fed into the circuit is at least partly taken from the environment before heating takes place, and then flows back into the environment after having been blown onto the crockery: in this manner, in fact, although damp air gets into the environment, the circuit is simplified even further while ensuring that the machine operates optimally. Further advantageous features will be set out in the appended claims.

These features as well as further advantages of the present invention will become apparent from the following description of an embodiment thereof as shown in the annexed drawings, which are supplied by way of non-limiting example, wherein:

Fig. 1 is a sectional side view of a dishwasher according to the present invention;

Fig. 2 is a sectional front view of the dishwasher of Fig. 1; Figs. 3, 4 and 5 show a detail of the hydraulic circuit arranged upstream of the pump of the machine of Fig. 1 in three different operating conditions;

Fig. 6 is a sectional view of the pump of the machine of Fig. 1;

Figs. 7 and 8 are two outside views of the pump of Fig. 6;

Fig. 9 shows the machine of Fig. 2 equipped with a device for breaking the fluid vein of the supply water flow;

Fig. 10 is a detailed view of the device for breaking the fluid vein of the supply water flow of Fig. 9;

Fig. 11 shows a detail of the well according to a variant embodiment of the machine of

Fig. 2; Fig. 12 shows a detail of the well according to a further variant embodiment of the machine of Fig. 2;

Fig. 13 illustrates a first operating mode of the variant of Fig. 12;

Fig. 14 illustrates a second operating mode of the variant of Fig. 12.

Referring now to Fig. 1, there is shown a dishwasher 1 which comprises a tub 2 that houses two racks 3 and 4, which are typically slideable on suitable guides so that they can be extracted from tub 2; in this regard, it should be noted that machine 1 is shown in

Fig. 1 with door 5 partially overturned and rack 3 partially extracted for illustration purposes only.

Two rotary sprayers are arranged under racks 3 and 4, i.e. an upper sprayer 6 and a lower sprayer 7: these sprayers (per se known) typically comprise two hollow blades 6A, 6B,

7A, 7B having a set of nozzles aiming at the rack to be sprayed; blades 6A, 6B, 7A, 7B are rotatable relative to the racks, so that they can spray all of the crockery contained therein as they rotate.

Fig. 1 also shows the channels used for conveying the fluid towards sprayers 6 and 7, i.e. upper duct 8 and lower duct 9, which are in fluidic communication with the cavities of blades 6A, 6B, 7A, 7B on one side and with a flow distributor 10 on the other side, the latter being normally fitted with a shutter adapted to let the fluid flow towards either one of the two ducts 8, 9 or towards both of them.

Flow distributor 10 is fed by the water circulation means, in this example consisting of pump 11, which communicates with the flow distributor through outlet duct 19 of the pump itself, which according to the teachings of the present invention is of the type comprising an electric resistor 12, as will be described in detail with reference to Figs. 6,

7 e 8.

Proceeding back along the path followed by the fluid, pump 11 is put in communication with the tub through tub drain duct 13: in particular, tub 2 has a concave bottom and drain duct 13 extends towards pump 11 from the lowest point of tub 2.

Drain duct 13 usually opens on a collecting well 40, which is not shown clearly in Figs.

1 and 2 for simplicity, but will be described in detail with reference to the other drawings.

Referring now to Fig. 2, there is shown a simplified front view of a section of machine 1, wherein it is possible to see both air intake duct 14 and air delivery duct 15 that connect tub drain duct 13 to the outside environment.

In the region upstream of pump 11 where these intake and delivery ducts 14 and 15 connect to tub drain duct 13, there are two flow diverters 14A and 15 A, as shown in

Figs. 3, 4 and 5, the operation of which will be discussed later on. As far as pump 11 is concerned, it includes an impeller 1 IA driven by an electric motor

1 IB and is of the type fitted with a built-in electric resistor, as shown in Figs. 6, 7 and 8.

This pump 11 is of a per se known type and is analogous to the one described in patent

EP 1 507 914 in the name of AWECO APPLIANCE SYSTEMS GmbH & CO. KG, i.e. it is fitted with an electric resistor 12 housed in the shell of pump 11, in particular in the chamber of impeller HA. The operation of machine 1 is controlled by a control unit

(not shown), which will be dealt with later on.

In general, the method according to the present invention provides for generating an air flow for drying the crockery through air circulation means which, according to the invention, consist of the very same means used for water circulation, i.e. pump 11 that generates the wash liquid flow.

Furthermore, the air flow is heated in the hydraulic circuit of the wash liquid by the very same electric resistor used for heating the wash liquid.

Dishwasher 1 operates as follows: when a wash cycle is over, if the user wants to dry the crockery contained in racks 3 and 4, the wash liquid being present at the bottom of tub 2 is drained through a suitable drain duct, e.g. duct 41 located at the bottom of well 40, visible in the detailed drawings 3, 4 and 5; on duct 41 there is a valve (not shown) of a per se known type, which is adapted to shut off the flow section of duct 41 itself; as an alternative, a drain pump may also be used for carrying the liquid towards the sewage system.

In this regard, it should be pointed out that in the above-described embodiment well 40 is arranged downstream of drain duct 13.

Once the wash liquid has been drained outside the tub (e.g. through duct 41), different operating conditions can be used for carrying out the drying cycle: full recirculation, partial recirculation or no recirculation; all these operating conditions share the fact that the drying process is carried out without using any specially dedicated circuit; in particular, unlike the prior art there is no fan or electric resistor specifically employed for that purpose, since pump 11 is also used as a fan for blowing the air onto the crockery, and the air is heated by the same resistor 12 already used for heating the wash liquid.

Therefore, this solution provides a remarkable reduction in the number of components, and the dishwasher is simpler to manufacture as well.

Figs. 3, 4 and 5 show the three operating conditions of the machine illustrated in Figs. 1 and 2: full recirculation (Fig. 3), no recirculation (Fig. 4) and partial recirculation (Fig.

5).

The method adopted in the first of these cases includes the following steps: a- taking air from the tub through a drain duct 13, b- providing the air with pressure energy by means of pump 11, c- conveying the air in ducts 8,9,10,19 afferent to rotary sprayers 6,7 arranged in tub 2 for blowing it onto the crockery.

As can be seen in Fig. 3, which illustrates this operating condition, the two flow diverters 14A and 15A are arranged in a manner such as to shut off the respective intake duct 14 and delivery duct 15, so that the air taken from tub 2 is conveyed to pump 11 by means of drain duct 13, heated by resistor 12, and then blown into outlet duct 19 by pump 11. Through the latter duct, the air reaches flow distributor 10, which distributes it into upper duct 8 and lower duct 9, thereby feeding sprayers 6 and 7.

The latter then deliver the hot air flow, through the respective nozzles, onto the crockery placed in racks 3 and 4.

It should be pointed out that sprayers 6 and 7 rotate when they are being fed with wash liquid, whereas they may rotate or not when they are being fed with air: however, this will not affect the drying effect because, even if the sprayers remain still, the air will nevertheless be distributed within the tub and the resulting turbulence will allow it to reach the crockery.

In this case, the moisture subtracted from the crockery is condensed onto the tub walls and is thus separated from the air, which keeps circulating.

For example, it is conceivable that the condensed water is collected on the tub bottom and then enters tub drain duct 13, from which it is then transferred into well 40, where it can be either accumulated or drained through duct 41 as necessary.

In this respect, it should be pointed out that, advantageously, the quantity of condensed water is relatively small (about 60 grams), and therefore it may not be necessary to drain it during the drying cycle, e.g. if a well having adequate capacity is used.

Through duct 13, the air is then conveyed again towards pump 11, where the cycle will begin anew.

As an alternative, an even simpler machine may be conceived wherein no air recirculation takes place.

When no air recirculation inside the machine is provided for, the method includes the following steps: a- taking air from the environment outside tub 2 through intake duct 14, b- providing the air with pressure energy by means of pump 11, c- conveying the air in ducts 8,9,10,19 afferent to rotary sprayers 6,7 arranged in tub 2 for blowing it onto the crockery, d- draining the air from tub 2 into the environment outside tub 2 through delivery duct 15.

This operating mode is obtained as shown in Fig. 4: here, flow diverters 14A and 15A have been moved in order to shut off duct 13 while at the same time opening intake duct 14 and delivery duct 15: in this case, the air is taken in by intake duct 14, which is in fluidic communication with the outside environment, and is conveyed into pump 11, where it laps electric resistor 12, thereby increasing its temperature from the ambient temperature to a higher temperature, e.g. a temperature between 60°C and 80⁰C, preferably about 70⁰C, so as to subtract humidity from the crockery more effectively, and then flows towards flow distributor 10 which, as described above, distributes it into upper duct 8 and lower duct 9, thus feeding sprayers 6 and 7; through the nozzles of the latter, the air is then let into tub 2, where it subtracts humidity from the crockery in racks 3 and 4.

The damp air then flows on along its path (pushed by the new air mass delivered by the nozzles) and is conveyed towards duct 13, which is intercepted by diverter 15 A and is open on delivery duct 15, which in turn is open on the environment. In this manner, the damp air is discharged outside the tub without needing special operating conditions capable of causing the humidity to be condensed inside the tub, unlike the preceding case or, more in general, all those cases wherein the air is recirculated inside the tub.

Though simple, this solution is extremely effective and allows to do without many machine components, while being also suitable for providing an inexpensive drying cycle obtained, for example, by leaving the electric resistor off: when the temperature of the environmental air is high enough, it is conceivable to dry the crockery, on which water stops in the form of droplets, by blowing onto the latter a jet of air at ambient temperature. In this case (electric resistor 12 off), it may be appropriate to extend the duration of the drying cycle, i.e. the operating time of pump 11, compared to the case wherein electric resistor 12 is turned on.

An intermediate operating condition is shown in Fig. 5, and corresponds to a condition wherein the recirculation of the air inside the tub is only partial: in this case, the method includes the following steps: a- taking a first air flow from the environment outside tub 2 through intake duct 14, b- taking a second air flow from tub 2, c- mixing the first and second air flows, d- providing the air with pressure energy by means of pump 11 (now acting as a fan), e- conveying the air in ducts 8,9,10,19 afferent to rotary sprayers 6,7 arranged in tub 2 for blowing it onto the crockery, f- draining a first air flow from tub 2 into the environment outside tub 2 through delivery duct 15.

As can be seen in Fig. 5, in this condition the two flow diverters 14A and 15A are brought to an intermediate position between the two positions shown in Figs. 3 and 4, thus shutting duct 13 as well as intake duct 14 and delivery duct 15 only partially. In this manner, it being understood that pump 11 and resistor 12 operate as described above, when the damp air mass comes out of the tub after having subtracted humidity from the crockery, a portion thereof is discharged into the environment through delivery duct 15, while the remaining portion flows on along duct 13 and is mixed with a fresh air flow supplied through intake duct 14. An environmental air flow, which is cold but has a low degree of humidity, is thus mixed with an air flow coming from the tub, which is hot and has a high degree of humidity: this allows some energy to be saved compared to the solution with no recirculation previously described with reference to Fig. 4, since a portion of the thermal energy used for heating the air is re-used. With this solution too, should any condensed water accumulate on the tub bottom, it will be drained into well 40 and then into the sewage system through duct 41. In this regard, it should be pointed out that in this solution duct 13 is straight and vertical, and well 40 is located on the axis of said duct, whereas pump 11 is arranged on a branch, so as to prevent the water drained from the tub during the drying steps from being put in circulation again.

For the machine to operate by exchanging air with the outside environment (as in the cases with partial recirculation or no recirculation described above), it is therefore necessary that dishwasher 1 comprises at least a tub 2 in which the crockery to be subjected to the washing action is to be placed, and a pump 11 for circulating a wash liquid flow in a hydraulic circuit comprising ducts 13, 19, 10,8,9,6A,6B,7A,7B afferent to and from tub 2, which is in fluidic communication with pump 11 by means of a tub drain duct 13, which in turn is in fluidic communication with an intake duct 14 and a delivery duct 15 afferent to the environment outside tub 2, so as to allow environmental air to be supplied into and drained from said hydraulic circuit, wherein between said drain duct 13 and intake duct 14 and delivery duct 15 there are respective flow diverters 14A,15A adapted to stop, either totally or partially, the fluidic communication between said drain duct 13 and the corresponding intake duct 14 and delivery duct 15.

The revolution speed of electric motor 1 IB that drives impeller 1 IA is typically approx.

2,600 rpm when pump 11 is used for conveying wash liquid towards the sprayers, whereas the electric motor is operated at a higher speed, e.g. a speed in the range of 3,000 to 5,000 rpm, in particular approx. 3,600 rpm, when the pump is used as a fan, i.e. when it is used for conveying air towards the sprayers.

Machine 1 is also equipped with a control unit (not shown) which controls pump 11 and/or resistor 12 even in the absence of any wash liquid in the tub, thus providing the drying cycle; the control unit is also used for controlling the electric motors that drive flow diverters 14A and 15 A, thus providing the different operating modes (full recirculation, partial recirculation or no recirculation) as described above.

As an alternative, it should be noted that flow diverters 14A and 15A may be operated manually by the user, e.g. by means of suitable levers.

Furthermore, the control unit regulates the revolution speed of the pump and possibly also the direction of rotation thereof; by appropriately shaping and/or sizing the blades of the pump/fan, it is conceivable to use one direction of rotation when the device is being used as a pump and the other direction of rotation when the device is being used as a fan.

The control unit receives the machine operating parameters, e.g. the temperature of resistor 12 detected by a suitable sensor, so that it can turn the resistor off when the temperature thereof reaches or exceeds a preset threshold value, for the purpose of preventing it from overheating or suffering any damage.

When turned on with no wash liquid, in fact, resistor 12 tends to reach a high temperature very quickly, and therefore it is essential to keep its temperature under control and supply power thereto accordingly, so as to prevent it from overheating or suffering any damage, when it is to be used for heating the air to be blown onto the crockery to be dried.

In this respect, an advantageously simple solution is to adjust the power supplied to the resistor by means of a circuit comprising a triac, as described, for example, in patent application TO2000A000406 in the name of the present Applicant. Referring now to Figs. 9 and 10, there is shown a solution which is particularly advantageous in terms of construction simplicity: in the embodiment of Fig. 2, the air delivery duct and air intake duct 15 and 14 end outside of the tub, opening on the environment surrounding machine 1 through corresponding apertures obtained in the casing. Alternatively, it is possible to avoid making holes in the machine casing by taking into account that the casing is not hermetically sealed from the outside environment.

In such a case, intake duct 14 should be fitted with a filter, so as to prevent any dirt possibly present in the environment from entering the hydraulic circuit.

These problems are solved by the variant shown in Figs. 9 and 10: here, intake duct 14 is afferent to device 25 for breaking the fluid vein of the supply water flow.

This device 25 is per se known (it is also referred to as "air break" by those skilled in the art), and is used for preventing any water backflow towards the water mains that supplies machine 1.

In short, supply pipe 27 is connected to the water mains and conveys the supply water flow towards fluid vein breaking device 25: as the water comes near perforated bulkhead 26, it drips downwards and crosses chamber 30 that communicates with the outside through pipe 29.

Because of the water dripping downwards, the continuity of the fluid vein is broken, and the water then flows into duct 28 that leads to the tub, thus allowing machine 1 to be supplied with the water necessary for the dish wash cycles while at the same time preventing any water from flowing back into the mains from machine 1 in the event of a malfunction, which might otherwise cause mains pollution.

In the embodiment shown in Fig. 9, intake duct 14 is in fluidic communication with chamber 30, which in turn communicates with the environment, thus allowing the hydraulic circuit to be supplied.

In this manner, the air coming in from intake duct 14 then flows through chamber 30, where any dirt present in the air can deposit; the chamber will then be cleaned before the next operating cycle.

This also makes it unnecessary to provide an outlet hole for duct 14, thus simplifying the construction of machine 1 even further. The above teachings may be subject to many variations, which however will still fall within the scope and objects of the present invention.

By way of example, resistor 12 may be housed outside pump 11, which can thus be a traditional one.

Likewise, it is also conceivable that the two flow diverters 14A and 15A are replaced with a single flow diverter having the same functionalities.

Although reference has been made so far to flow distributor 10, it is also clear that the latter may alternatively be absent or be replaced, for example, with a simple duct bifurcating into two branches directed towards the two sprayers.

It is also conceivable that air is blown by just one of the two sprayers, so as to dry the crockery contained in one rack only: this solution proves to be particularly advantageous whenever the machine is not fully loaded and crockery has been placed on one rack only.

Still with a view of simplifying the construction of the dishwasher, several other variants can be conceived in accordance with the present invention. The first one is shown in Fig. 11 : with this particular arrangement, the intake duct ends into the body of well 40, whereas delivery duct 15 is absent.

In this solution, when pump 11 is operating, a portion of the total air flow processed by the pump is taken from the tub while the remaining portion is taken from the outside through intake duct 14; the air may be discharged into the outside environment through a known device typically included in any dishwasher, consisting of a simple vent normally used for preventing any overpressure from building within the tub.

Such a solution only allows to obtain the operating mode described above as "partial recirculation", since the air flow blown onto the crockery comes partly from the tub and partly from the outside; in spite of this restriction of the possible operating modes, the machine construction is made considerably simpler.

Referring now to Fig. 12, there is shown a further variant: in this case, well 40 is located upstream of drain duct 13, thus being directly in fluidic communication with an aperture obtained in the tub bottom.

Here duct 13 extends substantially horizontally, and the intake port of pump 11 is higher than the bottom of well 40, so as to create, as will be explained in detail below, a sort of siphon.

Air intake duct 14, possibly fitted with shut-off valve 140, opens on duct 13 in the immediate vicinity of the intake port of pump 11.

In well 40 a liquid level sensor 41 of a per se known type may additionally be arranged, e.g. consisting of a simple float or a pressure switch, preferably a linear one. This solution allows to implement all of the above-described dishwasher operating modes. In Fig. 13, well 40 is totally empty and valve 140 is open: when pump 11 is turned on, the total air flow processed by it is taken partly from the tub (through well 40) and partly from the outside (through intake duct 14), thus providing the operating mode described above as "partial recirculation". When, on the contrary, intake duct 14 is shut off by valve 140, the air flow processed by pump 11 is wholly taken from the tub, thus providing the "full recirculation" solution. Fig. 14 shows the solution according to which the machine operates with no air recirculation: on the bottom of well 40 there is a certain quantity 42 of water or wash liquid which is sufficient to prevent the air, just like a siphon, from flowing from well 40 to pump 11 , resulting in the latter, when turned on, taking the whole air flow from the outside through duct 14, valve 140 of which is open.

In this solution as well, it can be seen that delivery duct 15, described above with reference to the machine of Figs. 1 and 2, has been apparently omitted: in fact, the air is discharged into the outside environment in this case as well, as in the variant discussed with reference to Fig. 12, through the vent of the dishwasher itself, thereby avoiding the use of additional components, which is advantageous in terms of construction simplicity.

In this solution, quantity 42 of liquid on the well bottom necessary for achieving the siphon effect discussed above is detected by liquid level sensor 41. According to a possible alternative solution, the wash liquid contained in the machine may be first drained thoroughly at the end of the wash cycles, and then a predetermined quantity 42 of water may be supplied in order to close the passage from the tub to the pump, as shown in Fig. 14.

This solution offers the additional advantage of providing a further simplification of the machine construction.

Claims

1. Method for drying crockery housed in a tub (2) of a dishwasher (1), in which dishwasher (1) the crockery is subjected, in the course of a wash cycle, to the washing action of a wash liquid flow generated by water circulation means (11) and conveyed onto said crockery through a hydraulic circuit, comprising the step of generating an air flow through air circulation means and conveying the air flow into the tub (2) and onto the crockery, thus removing humidity therefrom, and wherein the air circulation means coincide with the water circulation means (11), characterized by comprising the steps of: a- taking a first air flow from the environment outside the tub (2) through an intake duct (14), b- taking a second air flow from the tub (2), c- mixing the first and second air flows, d- providing the air with pressure energy by means of the pump (11), e- conveying the air in ducts (8,9,10,19) afferent to rotary sprayers (6,7) arranged in the tub (2) for blowing it onto the crockery, f- draining a first air flow from the tub (2) into the environment outside the tub (2) through a delivery duct (15).

2. Method according to claim 1, wherein the water circulation means and the air circulation means comprise a pump (11).

3. Method according to claim 1 or 2, comprising the step of heating the air flow in the hydraulic circuit.

4. Method according to claim 1, 2 or 3, wherein the air flow is heated by means of an electric resistor (12) arranged in the proximity of an impeller (1 IA) of the pump (11).

5. Method according to any of the preceding claims, comprising the steps of: a- taking air from the tub through a drain duct (13), b- providing the air with pressure energy by means of the pump (11), c- conveying the air in ducts (8,9,10,19) afferent to rotary sprayers (6,7) arranged in the tub (2) for blowing it onto the crockery.

6. Method according to any of claims 1 to 4, comprising the steps of: a- taking air from the environment outside the tub (2) through an intake duct (14), b- providing the air with pressure energy by means of the pump (11), c- conveying the air in ducts (8,9,10,19) afferent to rotary sprayers (6,7) arranged in the tub (2) for blowing it onto the crockery, d- draining the air from the tub (2) into the environment outside the tub (2) through a delivery duct (15).

7. Method according to any of the preceding claims, further comprising the step of heating the air in a chamber that houses the impeller (HA) of the pump (11).

8. Dishwasher (1) of the type comprising a tub (2) in which the crockery to be subjected to the washing action is arranged, and further comprising a pump (11) for circulating a wash liquid flow in a hydraulic circuit including ducts (13,19,10,8,9,6A,6B,7A,7B) afferent to and from the tub (2), wherein the tub (2) is in fiuidic communication with the pump (11) through a tub drain duct (13) extending between said tub (2) and said pump

(H), characterized in that the drain duct (13) is put in connection with the outside by an intake duct (14) and a delivery duct (15), being in fiuidic communication with said intake duct (14) and delivery duct (15) afferent to the environment outside the tub (2), for allowing air to be supplied into said hydraulic circuit from the external environment and to be drained into the external environment from said hydraulic circuit, respective flow diverters (14A,15A) being provided between said drain duct (13) and said intake duct (14) and delivery duct (15) which are adapted to totally or partially stop the fiuidic communication between said drain duct (13) and the corresponding intake (14) and delivery (15) ducts.

9. Dishwasher according to claim 8, characterized in that it implements the method according to one or more of claims 1 to 7.