The present invention relates to a device for treating laundry by means of water, particularly, a household washing machine or washer dryer machine. US3176484 describes a laundry machine that represents a closest state of the art for the present invention.

The washing and washer dryer machines have to meet stringent regulations with reference to the prevention of the flowback of a liquid (which could be polluted) from the household appliance into the water grid. To this aim, there are tests and regulation constraints, the meeting of which poses expensive and sometimes technically complex design choices.

This is particularly felt in the case of washer dryer machines ("washer dryers") of the prior art, in which a double-membrane non-return valve is used to prevent water from being able to flow back to the water grid in the case that a vacuum is applied thereto.

The object of the present invention is to provide a laundry treatment machine using water, having such characteristics as to obviate the drawbacks of the prior art.

A particular object of the invention is to provide a washing and/or washer dryer machine having such characteristics as to prevent water from flowing back to the water grid in the case of a vacuum applied to the duct in communication with the household appliance, and which is less expensive and/or structurally less complex than the washing and/or washer dryer machines of the prior art.

A further object of the invention is to propose an alternative solution to the known use of double-membrane non-return valves.

A further object of the invention is to provide a washing and/or washer dryer machine with an improved water supply system.

These and other objects are achieved by a laundry treatment machine according to claim 1 and 6.

This allows obviating complex and expensive double-membrane non-return valves, while ensuring meeting the stringent regulations described in the introduction.

Further advantageous aspects of the invention will be apparent from the following description of some embodiments thereof by way of non-limiting example, with reference to the appended Figures, in which:

• Fig. 1 is a schematic view of a laundry treatment machine, particularly a washer dryer machine, according to an embodiment of the invention;
• Fig. 2 shows an enlarged detail of a water supply system of the treatment machine in Fig. 1;
• Fig. 3 is an enlarged schematic view of a detail of the water supply system of the treatment machine according to an embodiment;
• Fig. 4 is a schematic view of a laundry treatment machine, particularly a top-loading washing machine, according to an embodiment;
• Fig. 5 is a sectional view of an upright length with air gap of a water supply duct of the treatment machine according to an embodiment;
• Fig. 6 is a schematic view of a laundry treatment machine, particularly a front-loading washing machine, according to an embodiment of the invention;
• Fig. 7 shows an enlarged detail of a water supply system of the treatment machine in Fig. 6;

With reference to the figures, and in accordance with a general principle of the invention, a laundry treatment machine, for example a washing machine 1 or a washer dryer machine 2, comprises a laundry container 3 suitable to contain the laundry to be treated, a treatment device, for example a washing tub 4 or a condensation unit 32, that uses water and that cooperates with the laundry container 3 for the purpose of the treatment (e.g., washing, drying, moisture condensation, etc.) of the laundry, a water loading system having a first supply duct 6 connectable to the water grid and in communication with the treatment device 4, 32, a drain duct 8 for draining the washing liquid from the treatment device 4, 32, a first supply electrovalve 7 arranged in the first supply duct 6, as well as an electronic control unit 9 that drives the first supply electrovalve 7 to supply grid water to the treatment device 4, 32 depending on a predetermined and/or user-selectable treatment program.

According to an aspect of the invention, the first supply duct 6 comprises, downstream of the first supply valve 7 and upstream of the treatment device 4, 32, an approximately vertical upright length, with an air gap or interspace 10 formed between an upper tube end 11 and a lower tube end 12 (concentrically) aligned with and facing the upper tube end 11, so as to prevent a water flow back into the water grid.

This allows obviating complex and expensive double-membrane non-return valves, while ensuring meeting the stringent regulations described in the introduction.

The laundry treatment machine can be a washing machine 1 (Figs. 4, 6) with a support and housing structure 15, inside which a washing tub 4 is housed (which forms part of the above-mentioned treatment device) provided with a front opening closable by a porthole door 16 frontally hinged to the housing 15. The laundry container 3 is housed inside the washing tub 4 in a rotatable manner about a horizontal or inclined axis, embodied as a perforated drum or bucket to receive the laundry to be subjected to a washing operation. The bucket 3 also defines a front opening arranged at the washing tub 4 opening, in order to be able to carry out the laundry loading and unloading.

The washing tub 4 is suitable to contain the washing liquid during the laundry washing steps.

In order to allow the loading of the washing tub 4 with grid water and cleaning substances and additives, the water loading system comprises, beside the first supply duct 6, one or more further supply ducts 17, 18 extending from one or more further supply electrovalves 19, 20 through corresponding detergent compartments 14 of a detergent drawer 13, up to the washing tub 4.

A drain duct 8 connects to the bottom 21 of the washing tub 4, with associated drain pump 22 which provides for the removal of the washing liquid from the tub 4 and which controls, together with the supply electrovalves 7, 19, 20, the liquid level within the tub 4.

In order to heat of the washing liquid contained in the tub 4, an electric coil resistor 23 may be provided for, which is arranged inside the tub 4, particularly on the tub bottom 21, in the interspace between the wall of the tub 4 and the laundry basket 3.

For stirring and mixing the laundry with the washing liquid, the laundry basket 3 may be actuated in rotation by an electric motor 24 and a transmission 25.

The operation of the washing machine 1 is controlled by an electronic, electric, or electro-mechanical control unit 9, operatively connected to a user control interface 26 which is located at an outer wall of the housing 15 and which allows selecting the washing programs and the characteristics thereof. In response to the selections carried out by the user by the user interface 26, the control unit 9 drives the various components of the washing machine 1.

The washing machine 1 may further comprise a recirculation system of the washing liquid with a traditional recirculation pump or by an ejector (jet pump) in flow communication with the bottom 21 of the washing tub 4 and the bucket laundry 3.

In accordance with an aspect of the invention, the first supply duct 6 is so located as to convey the grid water from the first supply electrovalve 7 (preferably directly) into the washing tub 4 and the upright length with the air gap 10 of the first supply duct 6 is advantageously arranged inside the detergent drawer 13.

This obviates the need to arrange, in the washing machine, an additional space for the air gap 10 and an additional system for the collection and drain of water that is not led away (for example, in the case of an obstruction) by the lower tube 12 of the air gap 10. In fact, the detergent drawer 13 collects and discharges all the liquids directly in the washing tub 4, ensuring that the zone of the air gap 10 always remains clear.

The characteristics of the treatment machine hereto described with reference to a front-loading washing machine similarly refers to top-loading washing machines (Fig. 4). In such machines, the laundry basket 3 has a loading opening 27, for example, of the shutter type, formed in a side wall of the basket 3 and which can be overlapped by an upper opening 28 of the washing tub 4 and of the support structure 15, which can be closed and opened by a hinged upper lid 29. In the top-loading washing machines, the detergent drawer 13 can be preferably formed or connected directly to the upper lid 29 and is arranged in flow connection with the various ducts at least when the upper lid 29 is closed (operative state of the machine).

In accordance with a non-claimed example, the laundry treatment machine is a dryer machine (not illustrated separately, since Fig. 1 shows a washer dryer machine incorporating, besides to the drying functions, also the washing functions). Besides the general characteristics and functions of the laundry treatment machine according to the invention, the dryer machine comprises a drying circuit with a suctioning group 31, a condensation unit 32, and a heating unit 33 mutually communicating by a drying duct 30 and configured to convey a drying air flow through the laundry container 3, in which the first supply duct 6 is located to convey the grid water from the first supply electrovalve 7 into the condensation unit 32 to cool and condense the moisture extracted from the laundry. In this case, the upright length with the air gap 10 of the first supply duct 6 is arranged upstream of the condensation unit 32.

In this manner the grid water can sprinkle the condensation unit 32 to extract the moisture from the drying air flow and, in the case that a vacuum was applied upstream of the first supply electrovalve, this would draw only air suctioned through the air gap 10.

In accordance with a further aspect of the invention, the laundry treatment machine is a washer dryer machine 2 (Fig.1) having the structural and functional characteristics of the washing machine for washing and those of the dryer machine for drying the laundry.

In this case, the first supply duct 6 can be located to convey the grid water from the first supply electrovalve 7 into the washing tub and/or in the condensation unit 32.

With further advantage, in the washer dryer machine 2 also, the upright length with the air gap 10 of the first supply duct 6 is arranged inside the detergent drawer 13.

In this manner, the grid water can sprinkle the condensation unit 32 to extract the moisture from the drying air flow and/or enter the tub 4 to the purposes of the washing operation, and, in the case that a vacuum was applied upstream of the first supply electrovalve 7, this would draw only air suctioned through the air gap 10.

Generally, besides the first supply duct 6, the water loading system could comprise:

• a second supply duct 34 connectable to the water grid and in communication with a second treatment device, for example the condensing unit 32, in the case that the washing tub 4 was the first treatment device,
• a second supply electrovalve 35 arranged in the second supply duct 34,

In the case of the washer dryer machine 2, the first supply duct 6 could be located to supply grid water from the first electrovalve 7 in the washing tub 4, and the second supply duct 34 could be located to supply grid water from the second supply electrovalve 35 to the condensation unit 32. Both the first 6 and second 34 ducts could form the corresponding air gaps 10 in the detergent drawer 13.

Figs. 3 and 5 illustrate exemplary embodiments of the air gap 10. Advantageously, the upper tube end 11 tapers in a convergent manner downwardly and forms a convergent nozzle that accelerates the water flow so as to create a liquid sheet having a spray with a reduced output width. The liquid exiting the convergent nozzle, passing through the air gap 10, reaches the lower tube end 12 (which may form a funnel-shaped edge 36 to collect the entire flow) located under the convergent nozzle of the upper tube end 11. The height 37 of the air gap, i.e., the vertical distance between the upper 11 and lower 12 tube ends can range from 2mm to 5mm, preferably about 3 mm.

Although the presence, which is possible, but not indispensable, of the funnel-shaped edge 36, the inner diameter of the lower tube 12 gradually tapers in a convergent manner upwardly moving near to the upper tube 11 end.

The convergence angle 38 of the upper tube 11 (i.e., the angle between two inner surface portions of the tube in a sectional plane comprising the central axis of the tube) can be advantageously in the range of 12° ... 17.1° ... 22°, while the convergence angle 39 of the lower tube 12 can be advantageously in the range of 4 ... 5.9° ... 8°.

The end portions of the upper 11 and lower 12 tubes can be tapered from a maximum diameter 40 of 6mm ... 7.5mm ...9 to a minimum diameter 41 of 2mm ... 3mm ... 4mm at the free ends facing the air gap 10, see Fig. 5).

It shall be apparent that, to the laundry treatment machine according to the present invention, those skilled in the art, in order to meet contingent, specific needs, will be able to make further modifications and variations, all of which anyhow fall within the protection scope of the invention, as defined by the following claims.