It is known that modern domestic washing machines, dishwashers and like are semi-permanently connected to the plumbing system, to be supplied, during their operation, with a flow of water and, obviously, are also connected to a drainage system for the discharge of waste water.

PRIOR ART The connection to the plumbing and drainage systems takes place through flexible hoses made of rubber, elastomeric or plastic material to ease the installation and to allow, when required, the movement of the domestic appliances.

Normally, for safety, at the outlet of the plumbing system a manually operated tap is foreseen which allows the water supply to be turned off when the domestic appliance is not in use and which prevents undesired leakages of liquid.

In many cases, however, particularly when the domestic appliance is of the"built-in"type, the tap is

arranged in an awkward position and it is often the case that it is left open permanently.

This means that the electrovalve for controlling the water flow, with which the domestic appliance is equipped, is permanently subject to the pressure of the water circuit.

In the long term this can cause malfunction of the apparatus which, fortunately, is generally designed to ensure, if installed correctly, that possible liquid leakages, due to a fault inside the machine, are discharged into the waste water collector.

The consequences are quite different in the case of a breakage of the flexible hose for connecting to the water supply.

The consequent water leakages cannot be collected and conveyed to a discharge (it is very rare that a plumbing is foreseen with a collector for waste water at floor level) and cause flooding with substantial damages.

The systematic closing of the safety tap, when the domestic appliance is not in use, reduces this risk but does not completely remove it, also because it is common to leave the apparatus unattended while in use, even during the night and often when nobody at all is present.

Even if the connection hoses are designed to withstand the pressure of the water circuit, in the long term,

through ageing, they can give way, particularly during the actual use of the domestic appliance, when the abrupt interruption of the water flow, imposed by the electrovalve, causes the well known water hammer effect.

For this reason and to avoid the risk of flooding, users are recommended to periodically check and change, after a given time period, the water connection hoses, a recommendation which is often not followed, particularly for built-in units, for which the accessibility to the connection hoses is very difficult, if not impossible.

It is thus desirable to equip electrodomestic apparatus which needs to be connected to a plumbing system with a system for protection against leakages, the consequent flooding and the damages caused by this.

DESCRIPTION The present invention solves this serious problem and equips the domestic appliance with a first hose for connecting to the plumbing system, housed in a second outer protection hose equipped with an offtake connected to the waste water collector. advantageously, the offtake connected to the waste water collector, which can end at the same point as the domestic appliance's discharge, can be equipped with a one- way device or valve, for preventing the domestic appliance's discharge flow from entering in the protection

hose.

BRIEF DESCRIPTION OF THE DRAWINGS The features and the advantages of the invention will become clearer from the following description of a preferred embodiment, made with reference to the attached drawings, wherein: - figure 1 shows, schematically, a washing machine connected to a plumbing system and to a waste water collector in accordance with the prior art; - figure 2 shows, in a combined section/front view, a fitting for connecting to the hydraulic connection fitting for washing machines, commonly used in the prior art; - figure 3 shows, schematically, a washing machine connected to a plumbing system and a waste water collector with a safety hose in accordance with the present invention; - figure 4 shows, in combined section/front view, the end part of a safety hose for washing machines and the relative connection fitting, in accordance with a preferred embodiment ; - figure 5 shows, in diametral section, a tee for the safety hose of figure 3, according to a preferred embodiment; - figure 6 shows, in combined section/front view, a first end part of a safety hose for washing machines and

the relative connection fitting, in accordance with a second embodiment of the present invention; - figure 7 shows, in combined section/front view, a tee for the safety hose, in accordance with a second embodiment; - figure 8 shows, in combined section/front view, a second end part of a safety hose and the relative connection fitting, in accordance with a second embodiment; - figure 9 shows, in combined section/front view, an end part of a safety hose with an offtake fitting particularly indicated for direct coupling with the electrovalve of a domestic appliance (washing machine or like) or the safety tap of a plumbing system; - figure 10 shows, in section, a tee with a dual- effect one-way valve, particularly indicated for direct coupling with the discharge of a domestic appliance or with the hose leading into the waste water collector.

BEST WAY OF EMBODYING THE INVENTION With reference to figure 1, a washing machine 1, dishwasher and like, is usually connected to a plumbing system 2 through a flexible hose 3, ending with connection fittings 4,5, with the interposition of a tap 6 or manually operated shut-off valve.

At the same time the discharge 7 of the domestic appliance is connected to the waste water collector 8

through a flexible hose 9.

The installation norms generally foresee that the hose 9 forms an inverted siphon at a predetermined height H, falling within a maximum and minimum, to ensure that the water content in the machine, in normal working conditions, does not pour directly into the waste water collector and at the same time that in the case of malfunction and of excessive filling the excess water can flow towards the discharge, without overflowing through other openings of the machine.

The hose 9, which does not undergo any substantial water pressure, is normally fitted elastically, without any particular force, onto the pipe union leading into the waste water collector 8 and is an integral, even if removable, part of the washing machine.

The discharge hose 3, on the other hand, constitutes a replaceable feature, is formed in rubber or plastic material, reinforced with a cord or metallic mesh to withstand the pressure of the plumbing system and ended with two connection fittings 4,5.

Figure 2 shows the typical structure of such fittings, intended to be screwed on to a threaded pipe union 10 with a standard diameter and thread, conventionally referred to as "gas fitting.

The fitting comprises a lock nut 11, made of metal or

plastic, with support shoulders 19 and internal thread, wherein is inserted a cylindrical flanged plug 12, with an axial hole and flange 33, made of stiff plastic or metal, with the superposition of a resilient gasket 13 in the form of a washer and with the possible further superposition of a metallic mesh filter 14.

The plug 12 is inserted in the end of the hose 3 which is permanently anchored to the plug through crimping of an outer metallic lock nut 15.

Normally the hose has an outer diameter in the order of 16 mm and the lock nut 11 an outer diameter in the order of 40 mm and internal diameter of the support shoulders in the order of 17-20 mm, so as to allow the easy insertion of the hose 3 in the lock nut.

Naturally, in assembling the fitting, firstly the lock nut 11 must be inserted onto the hose 3 and then the crimping of the lock nut 15 on the hose must be carried out.

When the lock nut 11 is screwed onto the pipe union 10 (for the outlet of the plumbing system or for the inlet of the washing machine) the flange 33 of the plug 12 and the gasket 14 are pressed between the lip of the pipe union 10 and the shoulder 19 of the lock nut 11, ensuring the perfect sealing of the fitting.

Unfortunately, as already mentioned, the hose 3 is

prone to breaking, with the consequent leakages.

According to the invention, as shown in figure 3, to avoid the serious drawback of possible leakages, the connection hose 3 to the plumbing system is entirely housed in a second protection hose 16, coaxial to the first, with an inner diameter much greater than the outer diameter of the first hose 3 and for example in the order of 28-30 mm.

The protection hose 16 fits directly, as we shall see, onto the connection fittings of the first hose 3 and is equipped with an offtake 17 for its connection to the waste water collector 8, through a tee 21 with two inlets respectively connected to the outlet of the offtake 17 and to the outlet of the discharge hose 9 of the washing machine respectively.

In this way, in the case of breakage of the hose 3, the liquid leakages are contained in the protection hose 16 and conveyed, through the offtake 17, into the waste water collector.

It should be noted that in this case the hose 16 and the bypass 17 do not come under pressure: the presence of the tap 6, or even only of the restriction consisting of the pierced plug 12 of the outlet fitting, ensure that the maximum flow rate of liquid emitted into the hose 16, in the case of the complete breakage of the hose 3 and with a pressure in the plumbing system even up to 7 Bars, does not

exceed 10-15 litres/minute. This flow rate can be easily drained, without any pressurisation, in a drain hose with a useful cross-section of 4.5 cm2 (corresponding to a circular crown with an outer diameter in the order of 28-30 cm and inner diameter of 16 mm).

The endings of the protection hose and of the offtake fitting can thus be implemented extremely simply and in many ways.

Figure 4, wherein, as for the subsequent figures, the elements which are functionally and structurally equivalent to those of figure 2 are identified by the same numerical references, shows an embodiment which is preferred for its simplicity.

In figure 4 the lock nut 11 is equipped with a cylindrical sleeve 18 extended on the shoulder 19 in the opposite direction to that of the threaded part of the lock nut.

The rest of the fitting is unchanged with respect to figure 2.

Preferably, but not necessarily, the sleeve 18 exhibits an outer surface which undulates with circumferential corrugations.

Onto the sleeve 18 is inserted the end of the protection hose 16, made of rubber or plastic, preferably of the corrugated bellows type, to give greater flexibility

and axial compressibility to the hose.

The corrugations of the two elements sealingly engage with each other, preventing the relative axial sliding. The structure of the opposite end fitting is exactly the same.

As far as the assembly structure is concerned the axial compressibility of the hose 16 allows the insertion into said hose 16 of the hose 3 with the ends extended beyond the protection hose, the insertion of the lock nuts of the end fittings onto the hose 3 and the anchoring through crimping of the flanged plug 12 to the end of the hose 3 to be carried out.

Once the lock nuts 11 of the end fittings have been tightened onto the pipe union 10, for inlet and outlet respectively, the hose 16 can be axially stretched so that its ends form a force fit coupling with the tailpiece 18 of the two end fittings. In order to obtain the offtake 17 of figure 3 the same constructive criteria are used: as shown in figure 5 a tee 20, made from stiff plastic, is fitted onto the water connection hose 3, before the assembly of the end fittings and their ends are shaped to receive the ends of two parts of the protection hose 16. The third end 23 is suitably sized and shaped to receive an end of the offtake 17, with the other end connected to the inlet 8 (Fig. 3) of the waste water collector, through the tee 21.

It is also clear that many variants can be made.

For example the protection hose 16 can be smooth, without corrugations and the relative axial shortening, necessary for carrying out the assembly of the inner parts, can be obtained simply by exploiting the clearence available between inner water hose 3 and protection hose 16, which is folded in waves on the inner hose.

The fixing of the hose 16 onto the sleeves can be obtained with a hose clamp or simply with a modest forcing.

The figures 6,7, 8 together show, in a composite section/front view, a variant embodiment, of two respective end fittings (figures 6,8) of the water hose 3 and of the protection hose 16 and of the intermediate tee (figure 7) of the protection hose 16.

In this embodiment the ends of the hose 16 are deformed, elastically or by moulding or even thermoforming, so as to form a flange 24 which couples with the shoulder 19 of the fixing lock nut (possibly with the interposition of an anti-friction washer.

The anchoring of one end of the inner hose 3 to the flanged plug 12 (figure 8) takes place in the way already seen, and the flange 33 of the plug 12 superposes onto the flange 24 to be sealably pressed, with the help of a gasket 13, when the lock nut 11 is screwed onto the pipe union 10.

The anchoring of the other end of the hose is exactly the same, with the only difference being that the plug 12

is divided into two elements: a connection hose 25, with an external thread, anchored to the end of the hose by the crimping of an outer lock nut, and a flange 26, with an internally threaded pipe union, equipped with a hexagonal, simple notched or cross-shaped seat for screwing the threaded pipe union onto the hose 25, as a final step of the assembly operation of the group.

The tee (figure 7) consists of a rigid body 27, moulded in plastic or cast in metal, equipped with two pipe unions 28,29 with external thread, which form a support shoulder for the end flanges 24 of the two parts of the protection hose 16 which are pressed by two fixing lock nuts 30,31, screwed on to the pipe unions 28,29, respectively.

The offtake pipe union 32 can be smooth, as shown, or shaped like the two pipe unions 28,29.

Many other variants can be brought to this.

For example fast-on fittings and fitting which incorporate the tee can be foreseen.

In particular, to stop the reverse flow of waste water towards the bypass 17 (Fig. 3) the tee 21 for connection to the waste water collector 8, or even the bypass itself 17, can be equipped, for safety, with a one-way device, consisting, in its most simple embodiment, of an elastic tongue 34 which, in the case of the output from the washing

machine's drain hose, closes the end of the bypass 17 and opens only by virtue of the presence of liquid in the offtake 17.

To periodically check the water supply hose and the seal of the fittings one only has to partially disassemble the group, in particular the tee or the offtake 17 and check for the absence of traces of liquid in it.

More simply it is possible to implement the offtake 17 and/or the parts of the protection hose and/or the tee in transparent plastic, so as to be able to check for the absence of liquid inside, without need of any partial disassembly operations.

It is also possible to foresee, inside the protection hose, a sound alarm device, with vibrating foils, which is even activated by only a small flow of liquid in the protection hose.

It is also clear that the protection hose 16 and the offtake 17 can consist of a single piece, obtained by moulding, rotoforming, thermowelding and similar procedures, thus eliminating the use of an intermediate tee as a separate element.

It is also clear that the different embodying solutions presented can be used in combination.

Possibly the tee, the offtake 17 and the pipe union for fitting the protection hose can be integral with the

washing machine or with an intake group also comprising the manually operated safety tap.

Figure 9 shows this solution.

Immediately upstream from the washing machine's electrovalve 134, and possibly integral with it, a double fitting 35, with an inner channel 36 for sending water to the electrovalve and an outer inlet and outlet channel 37, is formed.

The fitting 35 is equipped with a pipe union 38, internally threaded, for example with 3/8"gas threading, on which a threaded hose is screwed, with a fastening nut 139, which constitutes the end of the hose 3 for delivering water from the plumbing system.

Coaxially to the pipe union 38 and outside of it a hose 39, of the type already seen, threaded on the outside for anchoring an end of the protection hose through a threaded lock nut, is formed.

The hose 39 constitutes the inlet of the outer channel 37.

A similar pipe union 40, with outer threading for anchoring the offtake 17 through a threaded lock nut constitutes the outlet of the channel 37.

It is clear that the double fitting 35 can also be connected to the outlet of the safety shutter of the plumbing system, rather than at the inlet of the domestic

appliance and in this case the valve 134 represents the manually operated shutter/tap of the unit.

Figure 10 shows a preferred embodiment of a tee 21, incorporating a dual-effect one-way valve, for coupling with the offtake 17, with the discharge of the domestic appliance and with the waste water collection and disposal unit.

The fitting consists of a hollow cylindrical body, with two inlet pipe unions 41,42, for coupling with the offtake 17 and with the discharge of the domestic appliance respectively.

In the cylindrical body a seat for housing a sliding cage 43, in which a ball 44 slides freely, is formed.

The cage is held in position by two opposing abutment elements 44,45, at least one of which is removably screwed into one of the pipe unions.

From the cylindrical body branches off a discharge pipe union 46 for connection to the waste water collector.

When the domestic appliance is active in the discharge stage, the water flow F1, entering into the pipe union 42, pushes the ball 53 towards the pipe union 41 and causes its blocking off, so that the water flow can flow towards the discharge but is prevented from entering the offtake 17.

In the case of breakage of the water supply hose, the liquid contained in the protection hose and in the offtake

17 acts upon to ball 43 which is pushed towards the pipe union 42 and causes it to be blocked off.

In this way the liquid can flow towards the waste water discharge but is prevented from entering the domestic appliance 25.

In the case of joint intervention of the domestic appliance and the protection system the ball goes into an intermediate position and allows the discharge both from the domestic appliance and from the offtake 17.