Dishwashing machine

Abstract

 A dishwashing machine comprises a wash tub (3), an electric pump (87) for supplying water from a bottom (3a, 88) of the tub (3) to a sprinkler system (83-86), a switchable device (40), operatively set downstream of a delivery section of the electric pump (87), for controlling supply of water to the sprinkler system (83-86), a water-storage system (30, 45, 46, 50) comprising a tank (30) and a control system including control means for issuing a command for start-up of at least one program for treatment of the dishes that includes at least one step of charging water from the water mains to the tub (3), at least one step of treatment of the dishes, and at least one the step of filling of the tank (30). The switchable device (40) comprises a casing (41), mounted displaceable within which is a distributor member, which can be actuated by an actuator for assuming a plurality of operating positions, amongst which at least one position of opening a first outlet (44), for supplying a first sprinkler (83), and of simultaneously closing another outlet (43), for supplying a second sprinkler (84). The casing (41) of the switchable device (40) has a third outlet (45) that is always open; i.e., it is open irrespective of the operating position assumed by the distributor member. The third outlet (45) is connected via a third pipe (46) to a first opening (39a) of the tank (30) that functions alternatively as inlet and as outlet for the water with respect to the cavity of the tank. Between the third outlet (45) and the first opening (39a) of the tank (30) valve means (50) operate, which can be controlled independently of the switchable device (40).

Description

Field of the invention

[0001] The present invention relates to a dishwashing machine of the type referred to in the preamble of Claim 1.

Prior art

[0002] Modem-day dishwashing machines are increasingly conceived for guaranteeing a high quality of the process of treatment of the dishes and an efficient exploitation of the energy and water sources. In this connection, dishwashing machines are equipped with auxiliary functional systems, in addition to their main hydraulic system provided for carrying out washing in the strict sense. A typical auxiliary system used on some machines is represented by a liquid-storage system, based upon the use of a tank external to the tub, generally set up against a stationary wall thereof. In some machines the storage tank is provided in the perspective of reusing, in a subsequent operating cycle, part of the liquid used in a previous cycle (typically, the liquid used in the last rinse of the dishes), or else to obtain, within at least one hot-treatment step of a washing cycle, a partial heating of water to be used in a subsequent step of the same cycle, exploiting the heat exchange that occurs between a wall of the tub and the tank set up against it.

[0003] In some solutions, filling of the storage tank is provided using the discharge pump of the machine and specific valve means, which can be controlled for deviating the flow of liquid forced by the pump towards a discharge pipe or else towards the tank. In other solutions, there is provided a dedicated pump, i.e., one additional to the washing pump and to the discharge pump. The known solutions generally prove costly, both on account of the complications that they introduce in the hydraulic circuit of the machine and on account of the need to envisage relatively complex valve means, in view of the need to guarantee the required tightness over time.

Object and summary of the invention

[0004] In its general terms, the object of the present invention is to provide a dishwashing machine equipped with a liquid-storage system that is simple and inexpensive to produce and reliable as regards operation.

[0005] An additional object of the invention is to provide a dishwashing machine of the above sort, the storage system of which is designed to charge into a corresponding tank both substantially clean water and is water that has been previously used for the purposes of treatment of the dishes, such as, for example, liquid used for a rinsing operation.

[0006] One or more of the above objects are achieved, according to the present invention, by a dishwashing machine having the characteristics referred to in Claim 1. Preferred characteristics of the invention are specified in the dependent claims. The claims form an integral part of the technical teaching provided herein in relation to the invention.

Brief description of the drawings

[0007] Further purposes, characteristics, and advantages of the invention will emerge clearly from the ensuing detailed description of embodiments provided purely by way of explanatory and non-limiting example, with reference to the annexed drawings, wherein:

• Figure 1 is a partial and schematic perspective view of a dishwashing machine according to a possible embodiment of the invention;
• Figure 2 is a partial and schematic perspective view of a lower portion of the machine of Figure 1;
• Figure 3 is a schematic perspective view of a device for storing liquid used in the machine of Figures 1 and 2;
• Figure 4 is a schematic perspective view of a first valve device used in a machine according to the invention;
• Figure 5 is a schematic perspective view of a second valve device used in a machine according to the invention;
• Figure 6 is a partial and schematic perspective view of an upper portion of the wash tub of the machine of Figures 1-2;
• Figure 7 is a detail of the device of Figure 3;
• Figures 8 is a perspective view of a fixing member used in the machine of Figures 1-2;
• Figure 9 is a partial and schematic perspective view of an upper portion of the machine of Figures 1-2, including the parts illustrated in Figures 6-8;
• Figure 10 is a detail of a system for lower coupling of the device of Figure 3 to a base of the machine of Figures 1 and 2; and
• Figure 11 is a schematic representation of a dishwashing machine according to an advantageous embodiment of the invention.

Description of preferred embodiments of the invention

[0008] Reference to "an embodiment" or "one embodiment" within the framework of the present description is intended to indicate that a particular configuration, structure, or characteristic described in relation to the embodiment is comprised in at least one embodiment. Hence, phrases such as "in an embodiment" or "in one embodiment" and the like that may be present in various points within the framework of the present description do not necessarily all refer to one and the same embodiment. Moreover, the particular configurations, structures, or characteristics may be combined in any adequate way in one or more embodiments. The references used in what follows are merely provided for convenience and do not define the sphere of protection or the scope of the embodiments.

[0009] The use of the term "fill" and of its derivatives, in the framework of the present description and the attached claims, does not imply that the entire volume of the storage tank described hereinafter must necessarily be completely filled with a liquid, given that - in the practical embodiment of the invention - said tank may, and preferably will, be filled only partially with a liquid. The generic term "water" is to be understood, according to the cases described and claimed, as water already used for the purposes of execution of a step of treatment of the dishes, such as, for example, a rinsing step, or else as water charged into the tub from an external water mains supply but not yet used for treatment of the dishes (and hence substantially clean water, i.e., substantially without residue of dirt removed from the dishes and/or of washing agents, such as a detergent or a lustring agent). Where not otherwise specified, within the framework of the present description and the attached claims, the term "effective", when used with reference to operation of a sprinkler system or of a sprinkler member of the machine, is intended to indicate that said system or member operates fully for the purposes of treatment of dishes, for example, washing or rinsing. In this perspective, effective operation of a sprinkler member implies that the water comes out of the holes or nozzles of said member with jets of a height sufficient to reach the dishes contained in the tub so as to be able to carry out its function for the purposes of treatment.

[0010] It should moreover be pointed out that in the sequel of the present description only the elements useful for an understanding of the invention will be described, taking for granted, for example, that the machine according to the invention comprises all the elements in themselves known for operation of a dishwashing machine, including a possible external cabinet thereof, a user interface, a control system, pumps, level sensors, heating elements, means for charging water from a domestic water mains supply, a dispenser of washing agents, a system for sprinkling water on the dishes, etc.

[0011] Represented schematically in Figure 1 is a dishwashing machine 1 according to a possible embodiment of the present invention, provided with a liquid-storage system. The machine 1 is illustrated limitedly to the parts of immediate interest for understanding the present invention.

[0012] The machine 1 has a structure that comprises a base 2 and a wash tub 3, supported by the base 2. The base 2, made, for example, of injection-moulded thermoplastic material, preferably has open side walls and defines a housing space 2a, positioned within which are various functional components of the machine 1, amongst which, for example, a washing pump, a discharge pump, a pressure switch, a sump for collecting the washing liquid, etc., which here are not represented for reasons of greater clarity of the drawings.

[0013] The wash tub 3 is of a conception as a whole known, apart from the specific characteristics envisaged according to preferential embodiments of the invention, regarding the positioning of a device for storing liquid external to the tub itself.

[0014] The tub 3 comprises a lower wall 3a, an upper wall 3b and four side walls. Visible in the figures are only the stationary side walls of the tub 3, i.e., the rear wall 3c, and the right-hand and left-hand walls, designated by 3d and 3e. The fourth side wall of the tub 3, i.e., its front wall, is constituted by an internal shell of the door of the machine, here not represented (the so-called "counter-door"). From Figure 1 it may be seen how the lower wall 3a of the tub defines a central opening 3a', mounted at which is the already mentioned collection sump integrating the filtering system of the machine; it is to be noted that in Figure 1, for reasons of greater clarity, the bottom wall of the tub and other components normally present in the housing space 2a, such as the aforementioned sump, a washing pump, a discharge pump, etc., are not represented.

[0015] The liquid-storage system that equips the machine 1 basically includes a storage device or tank, designated by 30 in Figure 1, and a corresponding filling/emptying arrangement that includes valve means, designated by 40 and 50 in Figure 2. As may be clearly seen, the tank 30 substantially extends on the outside of the tub 3, whereas the valve means 40 and 50 are substantially installed within the space 2a for housing the base 2.

[0016] Figure 3 illustrates a preferential embodiment of the tank 30, which basically consists of a hollow body 31 made of plastic material, having a generally flattened configuration and preferably made of a single piece. A hollow body of this sort can, for example, be advantageously obtained by blow moulding of thermoplastic material.

[0017] As may be appreciated also from Figure 1, the body 31 of the tank 30 has a first vertical portion 34 that - in the installed condition - extends axially in the direction of the height of the tub 3, generally facing and parallel to a side wall of the latter, in particular the right-hand stationary wall 3d. The body 31 of the tank 30 then includes a second generally horizontal portion, designated by 35, that has dimensions and section of passage that are decidedly smaller than those of the portion 34 and substantially extends perpendicular to the latter, the portions 34 and 35 being connected to one another by means of a radiusing stretch 34a. As may be clearly seen also in Figure 1, the horizontal portion 35 of the body of the tank 31 generally faces and is parallel to the upper wall 3b of the tub 3. Said horizontal portion 35 has, in its face facing the upper wall 3b of the tub 3, an opening (designated by 36 in Figure 7), for being set in a position corresponding to a corresponding opening of the tub 3. As will be seen, the portion 35 of the hollow body 31 is intended for connecting the upper region of the portion 34 to the tub 3.

[0018] The tank 30 has lower opening. In one embodiment, at the lower end of the vertical portion 34 of the body 31, in a substantially central position, a restricted terminal portion, designated by 39, is defined. Preferably, the aforesaid opening - designated by 39a in Figure 3 - is provided at the restricted terminal portion 39, in the part thereof facing the tub 3 or the base 2.

[0019] The arrangement for filling and emptying the tank 30 used in the machine of Figures 1 and 2 in part exploits the valve means used for supplying selectively the sprinkler members - not represented - in order to carry out treatment programs on a reduced load or to carry out alternating washing and rinsing steps (i.e., ones carried out by supplying just one or both of the sprinklers, or else by supplying alternatively one or the other of the sprinklers).

[0020] These first valve means hence comprise a device for alternating supply of the sprinklers, designated by 40 in Figure 2. The device 40, like the similar devices according to the known art, has a casing 41 provided with an inlet 42, for connection to the delivery of a known washing pump, and two main outlets 43 and 44, connected, respectively, to the supply of the upper sprinkler and of the lower sprinkler, the outlet 43 preferably having a smaller section of passage than the outlet 44. Mounted displaceable within the casing 41 is an open/close member or distributor, which can be actuated by a corresponding actuator, isolated from the fluid, for assuming at least one first position, of opening of both of the outlets 43 and 44, and at least one second position, of opening of the outlet 44 and of closing of the outlet 43 and/or vice versa, all according to the known art. For example, the aforesaid distributor member can have the shape of a disk or of a circular sector, with one or more through holes, and be mounted displaceable in front of the aforesaid outlets 43 and 44.

[0021] According to a characteristic of the invention, the device 40 is configured in such a way that the casing 41 additionally defines a further outlet, designated by 45, which is always in fluid communication with the inlet 42, irrespective of the operating position of the aforesaid distributor member. Connected to said outlet 45, which preferably has a smaller section of passage than the outlets 43 and 44, is the first end of a pipe or duct, designated by 46 in Figure 2, the second end of which is connected to the lower opening 39a of the tank 30, with interposition of second valve means of the filling arrangement, represented by a valve, designated by 50, of any known conception.

[0022] In the embodiment exemplified, the valve 50, represented in Figure 5, is a valve of an open/closed type, which includes a connector body 50a having an inlet 51, connected to which is the pipe 46, and an outlet 52, connected, with interposition of suitable sealing means, to the opening 39a of the tank 30. Operative between the inlet 51 and the outlet 52, within the body 50a is an open/close element, displaceable by means of an actuator, which, in the embodiment exemplified, is an electrothermic actuator 53, of a type in itself known. The valve 50 can be actuated by the control system independently of the device 40 and is of a normally closed type: consequently, in the absence of supply to the actuator 53, the pipe 46 is not in fluid communication with the inside of the tank 30.

[0023] In one embodiment, defined in the upper wall 3b of the tub 3 is a through hole, designated by 60 in Figure 6, which is preferably circular and formed in an area 61 of said wall 3b that is slightly drawn outwards. On the other side, as may be seen from Figure 7, the upper opening 36 of the tank 30 comprises a projecting attachment, defined in the face of the body portion 35, which is to face the upper wall 3b of the tub 3. In the example, said attachment basically consists of a cylindrical stretch 62, which is to be fitted in the hole 60, with possible interposition of sealing means. Coupled to the part of the cylindrical stretch 62 that projects within the tub 3 is a fixing member: for said purpose, in a possible embodiment the cylindrical stretch 62 is threaded. Represented in Figure 8 is a possible embodiment of the aforesaid fixing member, designated as a whole by 65, which advantageously functions also as shielding for the opening 32. In the example, the member 65 is basically configured like a plug, having a body made of a single piece of moulded thermoplastic material. The body of the member 65 has a ringnut part provided with internal screw 65a, connected to which, via upright portions 65b, is a front wall 65c. In this way, defined between the aforesaid ringnut part and the front wall 65c are radial passages 65d. In its annular ringnut portion, the body of the member 65 advantageously defines a seat for an annular gasket 66. As may be appreciated, for the purposes of upper fixing of the hollow body 31 of the storage tank 30, the cylindrical stretch 62 is fitted in the through hole 60 of the upper wall 3b of the tub 3, and screwed on the part thereof projecting into the tub is the member 65. The assembled condition may be clearly seen in Figure 9; it will be appreciated that, thanks to the drawn area 61, the member 65 does not constitute a significant encumbrance towards the inside of the tub 3.

[0024] It is to be noted that, according to other embodiments (not represented), the coupling between the attachment 62 and the member 60 could be of a type different from the one exemplified, and not threaded: for example, said attachment and member may be shaped for coupling by means of a known bayonet-coupling system.

[0025] In one embodiment, the body 31 of the tank 30 also integrates coupling means used for establishing positioning and fixing of the body itself to the base 2 of the machine 1. As may be noted, for example, in Figure 3, made integral in the restricted terminal portion 39 of the body 31 are two lateral flanges 70, provided with respective holes. From the same figure it may moreover be noted how, from the lower edge of the vertical portion 34, in lateral positions with respect to the terminal portion 39, there depart downwards two substantially vertical projections or pins 71, which are also made integrally in the body 31 and which preferably have a cylindrical or slightly frustoconical section. Both the lateral flanges 70 and the pins 71 can be easily made of a single piece with the body 31 in the course of the corresponding moulding operation.

[0026] On the other hand, the base 2 has coupling means designed to co-operate with the ones defined in the lower part of the body 31 of the tank 30. In this connection, in the embodiment exemplified in Figure 10, the base 2 has, in its side corresponding to the wall 3d of the tub 3, and preferably at its upper edge, at least two cantilever walls 72, defined between which is a space for positioning of the terminal portion 39 of the body 31. Defined in each cantilever wall is a respective seat 72a, for insertion of a corresponding pin 71. In the body of the base 2, in a position lower than the cantilever walls 72 there are then defined formations - one of which is visible, designated by 73 - provided with a respective hole, designed to receive a corresponding fixing screw 74, inserted passing in the opening of a corresponding lateral flange 70. Also the cantilever walls 72, with the corresponding seats 72a, and the formations 73, with the corresponding holes, are advantageously formed integrally in the base 2, in the course of moulding thereof. The screws 74 are preferably of a self-tapping type.

[0027] As may be appreciated, the coupling between the upper hole 60 of the tub 3 and the cylindrical attachment 62 (Figures 6 and 7) and the coupling between the pins 71 and the corresponding seats 72a of the base 2 (Figure 10) facilitates assembly and precise positioning of the body 31 on the structure represented by the base 2 and by the tub 3, in particular guaranteeing the correct position between the vertical part 34 of the body 31 and the side wall 3d of the tub 3. The presence of the cantilever walls 72 enables discharge on the latter, and hence on the base 2, of the weight of the tank 30, this being particularly useful when the tank is filled with water.

[0028] In general terms, the machine 1 according to the invention is equipped with a control system of its own with corresponding user interface, of a substantially known conception, which enables selection, start-up, and control of a plurality of washing programs, where at least one of said programs is configured for managing operation of the liquid-storage system.

[0029] For instance, in one embodiment, prior to the step of discharge of the liquid used for the last rinse, the control system of the machine governs opening of the valve 50 and start-up of the washing pump. The pump forces the rinsing liquid into the inlet 42 of the device 40 (Figures 2 and 4), and part of said liquid, in addition to being fed to one or both of the sprinklers, via the outlets 43 and/or 44, is free to flow into the outlet 45, and then reach the tank 30, through the pipe 46. The tank 30 is in this way progressively filled from beneath, irrespective of the operating position of the device 40. Preferably, for execution of said step, the open/close element internal to the device 40 is brought to assume the position of opening of just the outlet 43, considering that the branch of supply of the upper sprinkler of the machine is the one distinguished by the higher head losses.

[0030] The filling step may, for example, be timed. Since the capacity of the washing pump, the section of the various passages (the device 40, the pipe 46, and the valve 50), and the times of opening/closing of the valve 50 are known, the step of filling the tank 30 may in fact last a pre-set time in order to obtain a certain level of filling of the tank 30, which is substantially predetermined. It is to be noted that, advantageously, the horizontal portion 35 of the tank, with the attachment 62, the corresponding opening 36, and the member 65 (Figures 7-9) function as venting and/or overflow system for the tank 30 (in other words, in the course of filling and emptying of the tank 30, the air is free to exit from and, respectively, enter the tank 30 and, even in the case where the liquid introduced into the tank 30 were for any reason to reach the horizontal portion 35, the liquid in excess can drop back into the tub from above, through the passages 65d of the member 65).

[0031] After the programmed time, the control system interrupts supply of the actuator 53 of the valve 50, which hence re-closes and then starts the discharge pump, for evacuating from the machine the possible residue of rinsing liquid still present in the tub.

[0032] In the course of a subsequent washing program, for example, from its start-up, the control system issues a command for a new opening of the valve 50 in the absence of supply of the washing pump, preferably but not necessarily in the absence of a concomitant intake of water from the external water mains supply. In this way, the liquid present in the tank 30 can flow off by gravity via the pipe 46, first reaching the device 40, then the pump, and finally the sump of the tub 3, connected to which is the intake branch of the washing pump. Basically, then, in the emptying step, the liquid flows away into the tub from the tank 30 following a path that is opposite to the one followed during the filling step, irrespective of the operating position of the device 40. The liquid thus introduced into the tub can be used, in the example considered, after re-closing of the valve 50, for carrying out a first step of washing the dishes. The liquid discharged from the tank will be substantially at room temperature, and this enables, in addition to the recovery of liquid, also a certain energy saving for heating thereof (in particular, when the mains water has a temperature lower than room temperature). After carrying out the aforesaid first washing step, the liquid is then discharged from the tub via the customary discharge pump.

[0033] The volume of liquid charged into the tank 30 may be smaller than, greater than, or equal to, the volume necessary for carrying out a washing step. Hence, in the first case, the control system will issue a command for an additional step of charging water from the mains supply up to the level necessary (for example, detected with a suitable sensor, such as a pressure switch). In the second case, the valve 50 will be opened for a time such as to ensure a partial discharge of the tank 30, i.e., discharge of a volume of liquid substantially corresponding to the amount necessary to carry out the washing step. In the third case, the time of opening of the valve 50 will be such as to enable complete emptying of the tank 30. It may be taken for granted that, in the second case referred to, control of the valve 50, for the purposes of partial emptying of the tank 30, may also be obtained by exploiting a known level sensor present in the tub, such as a pressure switch (basically, when said sensor detects that the level of liquid necessary to carry out the washing step has been reached, the control system issues a command for closing the valve 50, which may even be of a solenoid type). It is likewise clear that - in more sophisticated embodiments - the process of filling/emptying of the tank 30 can be controlled by providing a corresponding sensor (for example, a turbine flowmeter) between the device 40 and the valve 50, or else between the valve 50 and the lower opening 39a of the tank 30.

[0034] In the embodiment described previously, the liquid charged into the tank 30 is a liquid that has already been used for treatment of dishes in an operating cycle, namely, rinsing liquid, said liquid then being made available in a subsequent operating cycle of the machine. In possible variant embodiments, however, the operating modalities of management of the liquid-storage system (filling and emptying of the tank 30, as well as use of the water) may vary from those previously exemplified. In this perspective, for example, in an advantageous embodiment, filling of the tank 30 may also be performed with substantially clean water during a treatment cycle. The water thus stored in the tank 30 can then be at least partially heated, in the course of one or more hot-treatment steps of the same cycle, thanks to the heat exchange between the tub 3 and the body 31 of the tank 30, in view of execution of a treatment step. In another embodiment, the substantially clean water can be charged into the tank 30 in the course of a treatment cycle then to be used in a subsequent treatment cycle: in such a case, the water discharged from the tank will be substantially at room temperature, and this enables a certain energy saving for heating thereof (as has been mentioned, the mains water has generally a temperature lower than room temperature).

[0035] A possible embodiment in this sense will now be described with reference to Figure 11, which uses the same reference numbers as the ones used in the previous figures to indicate elements that are technically equivalent to the ones already described above.

[0036] In the schematic representation illustrated in Figure 11, provided inside the tub 3 of the machine 1 are a lower basket 80 and an upper basket 81, designed to contain respective loads of dishes and mounted - in a way in itself known - so that they can be pulled out and/or removed through the front opening of the tub. The machine 1 has, as has been said, charging means, for filling the tub with water coming from a domestic water mains supply. Said charging means, which may be of any known type, are configured for charging the tub 3 with a substantially predetermined amount of water, it being possible for said amount to vary according to the type of treatment cycle and/or as a function of the operating step of a treatment cycle. In this connection, the charging means preferably include dosing means, such as a level sensor, for example, a pressure switch.

[0037] Once again according to the known art, the machine 1 has a sprinkler system, which includes at least one first sprinkler member and one second sprinkler member, designated by 83 and 84 respectively, for sprinkling water on the dishes contained in the baskets 80 and 81, respectively. The sprinklers 83 and 84 are preferably rotary sprinklers, set underneath the corresponding basket and at a distance therefrom, which have a respective hollow body that is rotatably mounted at the end of a corresponding supply pipe belonging to the main hydraulic system of the machine. The body of each sprinkler has - at least in the part thereof facing the respective dish basket - a series of holes or nozzles. In the example represented, the hydraulic circuit of the machine includes two supply pipes, designated by 85 and 86, for the sprinkler 83 and the sprinkler 84, respectively.

[0038] Designated by 87 is an electric washing pump, i.e., a pump driven by an electric motor, for example a centrifugal pump, which has an inlet section and an outlet section, which is in fluid communication with the inlets of the pipes 85 and 86, by way of the first valve means represented by the device 40. As already explained, the device 40 is switchable, upon command from the control system of the machine 1, at least between a first condition, where the delivery section of the pump 87 is in fluid communication with the sprinklers 83 and 84, respectively, via the corresponding outlets 44 and 43 and the pipes 85 and 86, and a second condition, where the delivery section of the pump 87 is in fluid communication with just one of the sprinklers 83 and 84, respectively, via the outlet 44 and the pipe 85 or via the outlet 43 and the pipe 86, respectively.

[0039] Mounted at the opening 3a' (see Figure 1) of the lower wall 3a of the tub is the corresponding collection sump, designated by 88, which has an outlet in fluid communication with the inlet section of the pump 87. As already mentioned, such a sump includes the system for filtering the water (understood as clean water, or else already added with washing agents or rinsing additives, or else already containing residue of dirt removed from the dishes). The level sensor previously referred to can be operatively associated to the sump 88.

[0040] As per the known art, for carrying out a step of treatment of the dishes, such as a washing step or a rinsing step, the water charged into the tub 3 from the external water mains supply reaches the bottom wall 3a and converges towards the sump 88. The water is sucked in by the sump 88 via the pump 87, which forces the water into the pipe 85 and/or the pipe 86, for supplying the sprinkler 83 and/or the sprinkler 84. The water at outlet from the sprinkler or sprinklers impinges upon the dishes contained in the baskets 80 and/or 81, and drops onto the lower wall 3a, to return to the sump 88 and then - after prior filtering - be re-circulated by the pump 87. At the end of the treatment step, the water present in the bottom of the tub (the sump 88 and the wall 3a) is evacuated from the machine 1, via a known discharge pump (not represented).

[0041] In the course of the treatment steps performed with liquid (washing and rinsing) the control system of the machine 1 governs the pump 87 at a given treatment speed, necessary for supplying the water - possibly previously heated - from the bottom of the tub 3 to the sprinkler system 83-35 and 84-86 so as to render effective operation of said system for the purposes of the treatment of the dishes. In other words, the motor of the pump 87 is driven at a speed designed to bestow a pressure upon the water in the pipe 85 and/or the pipe 86 so that the water comes out of the holes of the sprinkler 83 and/or the sprinkler 84 with height of the jets sufficient for striking the dishes contained in the respective baskets 80 and/or 81 and thus carry out the function of washing or rinsing; at the same time, the water passes through each sprinkler with sufficient pressure to cause rotation thereof, so that said dishes are cyclically impinged upon by the jets of water. At the end of the treatment step, the discharge step is carried out, with which the water previously used for treatment of the dishes is evacuated from the tub 3, via the discharge pump governed by the control system.

[0042] According to an advantageous embodiment of the present invention, the motor of the electric pump 87 is a controllable-speed motor, of any known type designed for the purpose. In a preferred embodiment, the motor is a permanent-magnet brushless motor, and the control system of the machine 1 includes a driving circuit - of a type in itself known - that enables variation and control with relative precision of the r.p.m. of the motor. The motor of the electric pump 87 may also be an asynchronous motor, with the control of its speed that is performed by means - which are also in themselves known - designed to partialize the supply current.

[0043] In this embodiment of the invention, filling the tank 30 is obtained by issuing a command for actuation of the motor of the pump 87 at a reduced speed, i.e., lower than the treatment speed that renders the sprinkler system effective.

[0044] More in particular, the control system is prearranged for driving the motor of the pump 87 in such a way that, in the step of filling the tank 30, the corresponding motor will turn at a reduced speed such that the sprinkler system is not effective. Said reduced speed is hence lower than the speed used in the course of the washing and rinsing steps and than the minimum speed necessary for obtaining from the pump 87 a pressure of the water sufficient for causing wetting of the dishes contained in the lower basket 80 and/or upper basket 81. For example, in the case of supply of the lower sprinkler 83, the jets at outlet from said sprinkler in the steps of filling the tank 30 will have a height indicatively comprised between approximately 3 mm and approximately 30 mm, preferably between approximately 5 mm and approximately 20 mm, even more preferably between approximately 10 mm and approximately 15 mm, smaller than the distance between the sprinkler itself and the dishes contained in the basket 80. It will consequently be appreciated that, in said steps of filling the tank 30, the water charged into the tub 3 from the water mains supply will remain substantially clean, even though it is introduced into circulation by the pump 87.

[0045] A practical example of operation of the hydraulic circuit of the machine 1, for the purposes of charging of the tank 30 with clean water is described in what follows.

[0046] At the end of charging of water into the tub, the control system issues a command for opening the valve 50 and actuates the pump 87 at the aforesaid reduced speed. It is to be noted that, in the step of filling the tank 30, it is not necessary for the water-heating element to be active. At start of the step of filling the tank 30, the device 40 is in, or is, for this purpose, brought by the control system into, the condition of outlet 44 closed and outlet 43 open.

[0047] In this way, in the course of the step of filling the tank 30, the pump 87 driven at the reduced speed forces the water both into the supply pipe 86 of the sprinkler 84 and into the pipe 46, towards the inside of the tank 30, as has been described previously. The section of supply of the upper sprinkler of the machine is distinguished by higher head losses. On this basis, the reduced speed at which driving of the pump 87 will be such that the water forced into the pipe 86 climbs up the pipe itself but, given the reduced head, only up to a certain point, without being able to reach the sprinkler 84 and/or without being able to supply it so that the water can exit from its holes. In effect, hence, in the pipe 86 the water does not manage to exceed a certain height, which depends (in a known way) upon the characteristics of the hydraulic circuit. This will in any case not prevent an at least partial filling of the tank 30, at least up to a level equal to the one reached by the liquid inside the pipe 86.

[0048] When the programmed level of filling of the tank 30 has been reached (as already mentioned in relation to the first embodiment discussed previously, the level of filling may be timed or else controlled by a corresponding sensor, for example, a volumetric turbine sensor), the control system issues a command for closing the valve 50 and for possible arrest of the pump 87. Next, the control system issues a command for a new charging of water into the tub, for the residual amount necessary to carry out a treatment step. Possibly, charging of water from the mains supply may come about in dynamic conditions, i.e., with the washing pump active.

[0049] In the course of at least one step of hot treatment subsequent to filling of the tank 30, the washing water present in the tub is first heated and then made to recirculate via the pump 87 and the sprinkler system 83-86, according to modalities in themselves known. In said treatment step, the control system drives the motor of the pump 87 at the treatment speed for supplying the sprinkler 83 and/or the sprinkler 84 with a pressure such as to render operation thereof effective, i.e., such as to cause the water sprayed by the sprinkler 83 and/or the sprinkler 84 to impinge effectively upon the dishes contained in the baskets 80 and/or 81 and to cause rotation of the sprinklers. In this way, the hot water will yield part of its own heat, not only to the dishes being treated, but also to the walls of the tub 3, including the wall 3d that the tank 30 is set up against: in this way, there is provided a heat exchange that generates a partial heating of the contents of the tank itself. It should be pointed out that, according to the type of treatment program set, the aforesaid treatment step can be carried out using just one of the sprinklers or both of the sprinklers: obviously, according to the cases, the control system will issue a command for consequent switching of the device 40. At the end of the treatment step, there is hence envisaged the step of discharge of the liquid from the tub 3, with the control system that governs the discharge pump accordingly.

[0050] Next, for example, immediately after the aforesaid step of discharge of the tub, the control system issues a command for carrying out the step of discharge of the tank 30, according to modalities similar to those already described previously; i.e., it issues a command for opening of the valve 50, in the absence of supply of the pump 87. In this way, the contents of the tank are poured back into the tub. As has been said, the water contained in the tank 30 has been in the meantime at least partially heated, and said circumstance enables reduction of the energy consumption if the subsequent treatment step envisaged by the cycle implies heating of the water.

[0051] As has been mentioned, in any case, discharge of the tank 30 may occur also in a treatment cycle subsequent to the one in the course of which substantially clean water has been delivered to the tank 30.

[0052] The fluid-dynamic characteristics of the hydraulic circuit of the machine 1 may possibly be established also in such a way that the step of filling the tank 30 with substantially clean water present in the tub can be obtained by driving the motor of the pump 87 at a reduced speed, and with the openings 43 and 44 of the device both open. In such an embodiment, in the course of the step of filling the tank 30, the pump 87 takes in water from the sump 88 and forces it both into the pipe 85 and into the pipe 86 (as well as into the pipe 46). Given the reduced pressure of the fluid at outlet from the pump 87, the water comes out of the holes of the sprinkler 83 with jets having a height insufficient to produce wetting of the dishes contained in the basket 80; i.e., it exits from the sprinkler without substantially reaching the dishes. On the other hand, the water forced into the pipe 86 may climb up the pipe itself, but only up to a certain point, given the reduced head, without being able to reach the sprinkler 84. Given the constancy of opening of the outlet 45 of the device 40, and the concomitant opening of the valve 50, part of the water forced by the pump 87 also reaches the inside of the tank 30, via the pipe 46.

[0053] The water that exits from the sprinkler 83 drops onto the bottom of the tub and converges in the sump 88, and is then sent back into circulation via the pump 87. The water is made to circulate in this way until the programmed level of filling of the tank 30 is reached. The control system then issues a command for closing of the valve 50. For the rest, operation of the machine 1 is similar to what has just been described above with reference to the case of opening of the outlet 43 and closing of the outlet 44 of the device 40.

[0054] Not excluded from the sphere of application of the invention is the case of opening of the outlet 44 and simultaneous closing of the outlet 43, with actuation of the pump 87 at a reduced speed. In such a case, the system can be conceived so that the water will exit from the sprinkler 83 without reaching the dishes contained in the lower basket 80, and then drop back onto the bottom of the tub and converge in the sump 88, to be again sent back into circulation via the pump 87 as in the previous case.

[0055] It will be appreciated that the modalities of control of the motor of the pump 87 described above, based upon driving of the corresponding motor at the reduced speed, can be used also in order to carry out the steps of filling of the tank with liquid already used in the course of a treatment step, such as the rinsing liquid.

[0056] From the foregoing description, the characteristics and advantages of the present invention emerge clearly. The dishwashing machine according to the invention is simple and economically advantageous to produce, as well as reliable in operation.

[0057] The storage system exploits the washing pump, which is in any case provided on the machine, and does not entail substantial complications of its hydraulic circuit, exploiting in part valve means which are also in any case present on the machine, i.e., the deviator device for controlling alternating supply of the sprinklers. Said deviator device implies minimal adaptations, as compared to the ones normally used, which consist in simply providing a supplementary outlet, which is in any case always open. The deviator device thus remains extremely economically advantageous to produce, without adaptations of the corresponding distributor member and its sealing means, or complications in its actuation system. The fact that the outlet connected to the tank is always open enables discharge of the latter irrespective of the operating position of the deviator device.

[0058] Also the second valve means, which represent a simple open/close valve, are of simple and inexpensive conception, and present a high level of reliability in time also over the long period, for example, in terms of sealing, and call for actuation limited just to the steps of filling/emptying the tank, with a consequent reduced amount of wear.

[0059] The preferential embodiments described, based upon control of the motor of the washing pump at a reduced speed, enable filling of the tank also with clean water, i.e., water not contaminated by residue of dirt or by washing agents, but without implying a direct connection of the tank with the water mains supply.

[0060] In the advantageous embodiments illustrated, assembly of the tank 30 can be obtained with simple and elementary operations and enables a very compact configuration to be obtained. Correct positioning of the parts is ensured by the presence of the two positioning/constraint areas (in the upper part, at the roof of the tub, and in the lower part, at the base). The hole 60 provided in the upper wall 3b of the tub, in combination with the upper opening 36 of the body 31 enables availability of a vent and/or of a safety overflow for the tank 30.

[0061] It is clear that numerous variations may be made to the dishwashing machine described purely by way of example by the person skilled in the branch, without thereby departing from the scope of the invention as defined in the annexed claims.

[0062] It will be appreciated that the specific conformation of the tank of the storage system, as well as its positioning within the structure of the machine, may vary from the ones exemplified, without this calling into question the presence of the first and second valve means described previously, represented by the device 40 and by the valve 50.

[0063] The dishwashing machine according to the invention may be a dishwashing machine that comprises a sprinkler member set above the upper basket of the machine, in particular a third sprinkler member additional to the ones usually provided below the two baskets (such as the sprinklers 83 and 84 respectively, exemplified previously), for instance, a sprinkler substantially of a shower type, mounted on the upper wall 3b of the tub. Machines of this type, where the third sprinkler member can be of a stationary type, are generally known. In said embodiment, the device 40, with the corresponding casing and internal open/close element, will be configured so as to have, in addition to the outlets 43, 44 and 45, a further outlet connected to the supply of the aforesaid third sprinkler. Preferably, the steps of filling/emptying of the tank, according to the modalities described previously, based upon the control of the speed of the motor of the washing pump, may be performed when the device 40 is in the position of supply of the aforesaid third sprinkler member, the supply channel of which will be distinguished by the highest head losses.

Claims

1. A dishwashing machine comprising a wash tub (3), at least one lower basket (80) and one upper basket (81) for containing dishes in the tub (3), charging means for charging water into the tub (3) from a water mains, a sprinkler system (83-86), an electric pump (87) for supplying the sprinkler system (83-86) with water from a bottom (3a, 88) of the tub (3), a switchable device (40), operatively set downstream of a delivery section of the electric pump (87), for controlling supply of water to the sprinkler system (83-86), a water-storage system (30, 45, 46, 50), comprising a tank (30) defining an internal cavity designed to be set in fluid communication with the inside of the tub (3) for filling and emptying thereof, a control system including control means for issuing a command for start-up of at least one program for treatment of the dishes that includes at least one step of charging water from the mains supply to the tub (3), at least one step of treatment of the dishes, and at least one the step of filling of the tank (30),
wherein the sprinkler system includes a first sprinkler member (83), a second sprinkler member (84), a first supply pipe (85) for supplying the first sprinkler member (83), and a second supply pipe (86) for supplying the second sprinkler member (84),
wherein the switchable device (40) comprises a casing (41) having an inlet (42), connected to the delivery section of the electric pump (87), a first outlet (44) connected to the first pipe (85), and a second outlet (43) connected to the second pipe (85), there being mounted displaceable within the casing (41) a distributor member, which can be actuated by an actuator for assuming a plurality of operating positions, amongst which at least one position for opening one of the first and second outlets and simultaneously closing the other one of the first and second outlets,
characterized in that:

- the casing (41) of the switchable device (40) has a third outlet (45) that is always open; i.e., it is open irrespective of the operating position assumed by the distributor member;

- the third outlet (45) of the casing (41) of the switchable device (40) is connected via a third pipe (46) to a first opening (39a) of the tank (30) that functions alternatively as inlet and as outlet for the water with respect to said cavity; and

- between the third outlet (45) of the casing (41) of the switchable device (40) and the first opening (39a) of the tank (30) valve means (50) are operative, which can be controlled independently of the switchable device (40).

2. The dishwashing machine according to Claim 1, wherein the valve means comprise a valve of a normally closed type (50).

3. The dishwashing machine according to Claim 1 or Claim 2, wherein the control system is prearranged for causing:

- in the course of execution of a the step of filling the tank (30), opening of the valve means (50), subsequent closing of the valve means (50), and activation of the electric pump (87) at least for a period of time comprised between said opening and said closing; and

- in the course of execution of a step of emptying the tank (30), opening of the valve means (50) and subsequent closing of the valve means (50), in the absence of activation of the electric pump (87) at least for a period of time comprised between said opening and said closing.

4. The dishwashing machine according to Claim 3, wherein the control system is prearranged for performing the step of filling the tank (30) during a first treatment program and for performing a corresponding step of emptying the tank (30) during a second treatment program, subsequent to the first treatment program.

5. The dishwashing machine according to Claim 4, wherein the control system is prearranged for performing said filling step after a step of treatment of the dishes, prior to a corresponding discharge, the water charged into the tank (30) being rinsing water.

6. The dishwashing machine according to Claim 3, wherein the control system is prearranged for performing the step of filling the tank (30) and a corresponding step of emptying the tank (30) during one and the same treatment program.

7. The dishwashing machine according to Claim 3 or Claim 6, wherein the control system is prearranged for performing the step of filling the tank (30) after a step of charging water into the tub from the water mains and prior to a corresponding treatment step, the water charged into the tank (30) being substantially clean water.

8. The dishwashing machine according to Claim 7, wherein the control system is prearranged for performing the step of emptying the tank (30) after a step of hot treatment of the dishes.

9. The dishwashing machine according to any one of the preceding claims, wherein the control system is prearranged for:

- controlling the motor of the electric pump (87), in the course of execution of a treatment step, at a treatment speed such as to render operation of the sprinkler system (83-86) effective for the purposes of wetting the dishes;

- controlling the motor of the electric pump (87), in the course of execution of a the step of filling the tank (30), at a reduced speed, which is lower than the treatment speed and is lower than the minimum speed necessary for obtaining from the electric pump (87) a pressure and/or a head sufficient for rendering effective operation of the sprinkler system (83-86) for wetting the dishes.

10. The dishwashing machine according to Claim 9, wherein the motor of the electric pump (87) is one of a permanent-magnet brushless motor and an asynchronous motor with associated means designed to partialize the corresponding supply current.

11. The dishwashing machine according to any one of the preceding claims, wherein the tank (30) has a body (31) with a first portion (34), which is generally vertical and faces a stationary side wall (3d) of the tub (3), and a second portion (35), which is generally horizontal and faces the upper wall (3b) of the tub (3).

13. The dishwashing machine according to Claim 11, wherein:

- the tank (30) has a second opening (36), defined in a face of the second portion (35) facing the upper wall of the tub (3b);

- the upper wall (3b) of the tub (3) has a through opening (60) to which the second opening (32) of the tank (30) is operatively coupled, the second opening providing a vent opening and/or an overflow outlet of the tank.

14. A method for control of operation of a dishwashing machine that comprises a wash tub (3), at least one lower basket (80) and one upper basket (81) for containing dishes in the tub (3), charging means for charging water into the tub (3) from a water mains supply, a sprinkler system (83-86), an electric pump (87) for supplying water from a bottom (3a, 88) of the tub (3) to the sprinkler system (83-86), a switchable device (40), operatively set downstream of a delivery section of the electric pump (87), for controlling supply of water to the sprinkler system (83-86), a water-storage system (30, 45, 46, 50), comprising a tank (30) defining an internal cavity designed to be set in fluid communication with the inside of the tub (3) for filling and emptying thereof, a control system including control means for issuing a command for start-up of a plurality of programs for treatment of the dishes that each include at least one step of charging water from the water mains to the tub (3) and at least one step of treatment of the dishes,
wherein the sprinkler system includes a first sprinkler member (83), a second sprinkler member (84), a first supply pipe (85) for supplying the first sprinkler member (83) and a second supply pipe (86) for supplying the second sprinkler member (84);
wherein the switchable device (40) comprises a casing (41) having an inlet (42), connected to the delivery section of the electric pump (87), a first outlet (44) connected to the first pipe (85), and a second outlet (43) connected to the second pipe (85), there being mounted displaceable within the casing (41) a distributor member, which can be actuated by an actuator for assuming a plurality of operating positions, amongst which at least one position for opening one of the first and second outlets and simultaneously closing the other one of the first and second outlets,
characterized in that:

- in the course of operation of the electric pump (87), the water is forced into a third outlet (45) of the casing (41) of the switchable device (40) that is always open, irrespective of the operating position assumed by the distributor member, and is connected to a first opening (39a) of the tank (30) that functions alternatively as inlet and as outlet for the water with respect to said cavity;

- in the course of execution of the step of filling the tank (30), there is brought about opening and subsequent closing of valve means (50) operatively set between said third outlet (45) and said first opening (39a), moreover activating the electric pump (87) at least for a period of time comprised between the corresponding opening and closing of the valve means (50); and

- in the course of execution of a step of emptying the tank (30), there is brought about opening and subsequent closing of the valve means (50) in the absence of activation of the electric pump (87) at least for a period of time comprised between the corresponding opening and closing of the valve means (50).

15. The method according to Claim 14, wherein:

- in the course of execution of a treatment step, a motor of the electric pump (87) is driven at a treatment speed such as to render operation of the sprinkler system (83-86) effective for wetting the dishes;

- in the course of execution of a the step of filling the tank (30), the motor of the electric pump (87) is driven at a reduced speed, which is lower than the treatment speed and is lower than the minimum speed necessary for obtaining in the electric pump (87) a pressure and/or a head sufficient for rendering operation of the sprinkler system (83-86) effective for wetting the dishes.

Drawing