DESCRIPTION

The present invention relates to an electric resistance comprising a device for determining the turbidity level of a liquid.

More precisely, the object of the present invention is an electric resistance comprising a device adapted to detect the turbidity level of a liquid, preferably water, contained, at least temporarily, in a storage.

Even more precisely, the object of the present invention is an electric resistance comprising an immersion device capable of implementing said liquid turbidity detection function and further at least one sanitising function of said liquid and/or controlling and managing the temperature thereof and/or further accessory/ supplementary functions.

The invention mainly falls within the sector of the production of household appliances, more precisely in the field of making washing machines, washerdryers and/or dishwashers that may be used both within the scope of domestic and industrial environments.

Of course, nothing prevents the possibility of extending the use of the aforementioned immersion device, and relative electric resistance, also to other sectors, for example, in that of electric storage water heaters, tanks for storing water for food and domestic use or in all those water storages, temporary or not, where there is the need to determine and evaluate the chemi cal -physical characteristics of the water and/or a risk of proliferation of bacteria, germs and/or viruses.

It is in fact known that all the aforementioned household appliances, while differing from each other in constructive and functional characteristics, are associated with the presence of at least one "service" water storage and at least one electric resistance (or similar components) which has the task of heating and bringing said water to a temperature compatible with the service they must deliver, for example to meet a withdrawal of hot water for domestic or food uses or for washing laundry or dishes.

For their correct operation and an optimal implementation of specific operating programs (e.g., washing in case of washing machines or dishwashers, or heating and water supply in case of water heaters) it is necessary that such household appliances operate with service water of specific chemi cal -physical characteristics.

For example, it may be necessary to determine the concentration and nature of any suspended substances, generally insoluble solids, such as metal oxides, soaps (or their residues), fats, microorganisms, or any other particle which, being not dissociable into ions, may modify, also remarkably, the physical characteristics of the liquid, for example its transparency.

Hereinafter, for descriptive reasons, all this variety of substances potentially present in a liquid shall be referred to as "suspended particles".

Turbidimetry is an optical analysis method that allows determining the turbidity (or, equivalently, transparency) level of a liquid by using the absorption and reflection of light rays by suspended particles.

Since said method is well known to a person skilled in the art, it is not necessary to dwell on its specific characteristics.

On that occasion, it is therefore sufficient to specify how a light ray that crosses a liquid may interact with any suspended particles.

Such interaction mainly results in a deviation of the light ray, i.e. in a modification of its trajectory caused both by the presence of opaque particles, i.e. not transparent to light, and by particles having a refractive index different from that of the liquid in which they are found.

For a set of refraction, reflection and diffusion phenomena, part of the light energy may therefore be diffused in different directions from that of the ray incident against said particles; as a result, the light intensity of the ray that proceeds in the original direction is attenuated.

In other words, such phenomena may be used to detect the turbidity level of the liquid by using an analysis method that may be implemented by specific sensors, referred to as "turbidity" sensors, developed and available in various forms and types.

An example of a common turbidity sensor 1’ is shown in figure 1.

Such sensor 1’, of cylindrical or "button" geometry, comprises:

- a body 10’ for housing the electrical and/or electronic components (not shown), and at least

- a first seat 11’ for a light emitter 2’, for example LED, and

- a second seat 12’ adapted to contain a detector 3’ of the light emitted by the emitter 2.

Said seats 11’, 12’ may consist of two projections (hereinafter also referred to as appendices 11’, 12’) projecting from the body 10’ of the sensor 1’ and “transparent” to the light radiation, generally made of translucent plastic, i.e., able to be effectively crossed by the radiation emitted or to be intercepted.

Furthermore, when in operating conditions, said appendices 11’, 12’ are in contact and/or immersed in the liquid the turbidity level whereof is to be determined.

More precisely, such appendices 11’, 12’ are suitably spaced to define an intermediate cavity 13’ that may be filled by a volume of water that may be used as a “sample” for measuring the turbidity level.

Figure 2 instead shows a known application of the turbidity sensor 1’ just briefly described above.

More specifically, an application thereof is illustrated in a washing machine 4 ’(or washer-dryer) in order to determine, during one or more of its operating steps, the turbidity of the washing or rinsing water caused, for example, by the “dirt” removed from the treated garments and/or the relative lint (also called “fluff’) and/or residues of cleaners (or similar detergents).

In such machines 4’, the turbidity sensor 1’ is normally placed in the proximity of the bottom 400’ of the tank 40’ which acts as a storage for the service water (also referred to as "washing") and as a housing for the drum 41’ in which the clothes to be washed are loaded through a relative porthole 42’.

In such way, the aforementioned contact and interaction between the turbidity sensor 1’ and the service water is substantially ensured.

Often, said sensor 1’ is installed and positioned near the electric resistance 5’ for water heating.

This implies the need of providing, on said tank 40’ at least two distinct seats 401’, 402’, one for the turbidity sensor 1’ the other for the electric resistance 5’, with a consequent duplication of the functional components, such as, for example, the gaskets, and an increased risk of leaks due to their defects.

Such duplication of components may also lead to an increase in costs and production time.

In some cases, the positioning of the turbidity sensor 1 ’ in the proximity of the electric resistance 5’ could require heavy modifications to the typical structure of the tank 40’, for example the creation of a compartment (not shown in figure 2) sufficiently and adequately sized for housing both components.

Said "additional" compartment may also lead to an increase in the overall volume of the tank 40’ and, consequently, in the amount of washing water it may contain; this corresponds to greater consumptions of water and energy to heat it.

The same problems, especially the sealing defects, may also be found in the event that said turbidity sensor 1’, or similar solutions, is installed at the washing water recirculation pipes of a household appliance. See, for example, the dishwashers illustrated and described in the prior documents EP 1 602 315 Al and/or US 2012/090654 Al, in which a turbidity sensor is mounted, respectively, at the washing water distribution or washing chamber drain unit. Furthermore, many of these known turbidity sensors 1’ operate with visible light (therefore with a wavelength centred on 940 nm and low frequencies) in order to cross the material of the aforementioned appendices 11’, 12’, however at the expense of a penalisation of efficiency and precision in determining the turbidity level of water.

The purpose of the present invention is to eliminate the drawbacks of the prior art listed above, by designing an electric resistance arranged to integrate an immersion device adapted to detect the turbidity level of a liquid contained in a storage, for example of a washing machine, dishwasher or water heater (or similar household appliances), which is efficient, economical, reliable and of low energy consumptions.

More precisely, the object of the present invention is to use an electric resistance comprising an immersion device for detecting the turbidity of a liquid, in a known household appliance, for example a washing machine, dishwasher or a storage water heater or the like, without this involving substantial changes to the structure and/or basic components thereof.

A further object of the present invention is to provide an electric resistance comprising an immersion device for at least determining the turbidity of a liquid which allows retrofitting and/or upgrading operations of household appliances already produced and in operation.

A further object of the present invention is to provide an electric resistance comprising an immersion device for determining the turbidity of a liquid contained in a storage capable of also implementing a sanitisation and/or control and management function of the temperatures of said liquid and/or other accessory/ supplementary functions.

These and other objects are achieved according to the invention, with the features listed in the annexed independent claim 1.

Further features of the present invention shall be better highlighted by the following description of one or more preferred embodiments, in accordance with the patent claims and illustrated, purely by way of a non-limiting example, in the annexed drawing tables, wherein:

- Figures la and lb show, respectively, a perspective view and a relative section of a turbidity sensor according to the state of the art;

- Figure 2 schematically shows a section of a state-of-the-art washing machine, and a related detail, comprising the known turbidity sensor of Figure la- lb;

- Figures 3a and 3b show, respectively, a perspective view and a section view of a possible installation method of an immersion device for determining the turbidity of a liquid according to the invention;

- figures 4a, 4b, 5a, 5b show, in more detail, some components of the turbidity device of figures 3a-3b;

- figure 6 schematically shows a section of a washing machine, and a relative detail, comprising the turbidity device of fig. 3a-3b.

The elements of the immersion device of the invention for detecting the turbidity of a liquid are now described using the references contained in the attached figures. Not necessarily what described in the figures is to scale, with the purpose of highlighting some features instead of others.

It is also noted that any dimensional and spatial term (such as "lower", "upper", "inner", "outer", and the like) refers to the positions of the elements as shown in the annexed figures, without any limiting intent relative to the possible operating conditions.

In the present description and related drawings, at least initially, reference shall be made to an immersion device 1 for determining at least the turbidity of a liquid, for example water, contained within a generic storage of a household appliance and used for different purposes, e.g., such as, washing water, rinsing water, domestic water or the like.

Hereinafter, "storage" is therefore to be understood as any tank, vessel or container, made according to the most varied shapes, geometries and volumes and for which there is a need to determine the chemi cal -physical characteristics of the liquid contained therein or that may be stored therein.

For descriptive simplicity, regardless of the type of household appliance and its function, said liquid shall preferably be "service water" while the immersion device 1 responsible for determining its turbidity may be summarised in "turbidity device 1".

It should also be noted that said turbidity device 1 is particularly suitable for being integrated into household appliances which provide for heating the water contained in their storage, such as, without any limiting intent, washing machines, washer-dryers, dishwashers and/or in a storage water heater, heat pumps, solar storages or the like.

Even more precisely, as will be seen, the immersion turbidity device 1 of the invention may advantageously cooperate and be integrated with at least one of the components of said storage normally used to heat the service water, in particular with one or more electric resistances, or similar means.

Said electric resistance, electrically insulated with respect to the walls or the body of the storage, is advantageously of the "immersion" type.

It is known that such electric resistances, in order to properly carry out their specific heating function, must be "immersed" in the service water; consequently, the integration of the turbidity device 1 of the invention on said components ensures their contact with the service water, at least in operating conditions and in the absence of malfunctions of the household appliance.

The figures attached to this discussion therefore show an electric resistance 5 capable of being installed on an inner wall of a storage 40 of a household appliance 4 containing the service water to be heated for a specific use.

A flange 50 allows it to be mounted on a special seat 402 of said storage wall 40 and at the same time acts as a support for at least one heating element 51 and related electrical power supply connectors 52.

Although in the attached figures, the heating element 51 is shown as a coil, nothing prevents the possibility of adopting other similar types and geometries, among those known and already available.

Since, as anticipated, said resistance 5 is of the "immersion" type, once installed, its heating element 51 is substantially in contact with the service water to be heated.

According to the invention, at least one seat 53 is advantageously obtained for the installation and integration of the aforementioned turbidity device 1 on the flange 50 of said electric resistance 5, of a substantially known type and shape.

Without any limiting intent, said at least one seat 53 may consist of a hole (or slot) or through space which develops for the entire thickness of the flange 50, between its outer face 500 that has at least the aforementioned electrical connectors 52 and that inner one 501 which supports the relative heating element 51.

Once inserted and locked on said at least one seat 53 (for example, by interlocking, interference or equivalent techniques), the turbidity device 1 too will be protruding from the flange 50 and extended towards the inside of the storage 40 of the household appliance, so as to be, at least when in operating conditions, in contact with, and/or immersed in, the service water.

Said turbidity device 1 comprises:

- at least one emitter 2 of light radiation capable of crossing the service water, the turbidity level whereof is to be determined, and

- at least one detector 3 of said radiation which, due to any refraction, reflection and diffusion phenomena of caused by the "suspended particles" in the service water, may be attenuated in intensity, giving evidence of said turbidity and its degree.

When integrated with the electric resistance 5, the turbidity device 1 may be powered and/or cooperate with the power supply means already provided for the same resistance 5, although nothing prevents the possibility of providing a separate and dedicated power supply thereof.

In order to determine the turbidity of the service water, the emitter 2 of the turbidity device 1 may consist of a visible light, infrared light or, preferably, ultraviolet light emitter 2.

For the reasons that will be understood later and without any limiting intent, in the continuation of the present description, reference shall in any case be made to an ultraviolet emitter 2, i.e., consisting of an ultraviolet generator or phototransmitter 20 comprising one or more lamps or LEDs UVC 200, although this does not prevent the possibility of adding and using lower frequency LEDs. Consequently, the corresponding detector 3 may consist of a receiver device 30 capable of measuring the intensity, related to the turbidity degree of the liquid in which it propagates, of the ultraviolet radiation transmitted by the emitter 2 and reaching it.

Without any limiting intent, said detector 3 may comprise at least one ultraviolet light photoreceiver 30, for example in the form of a photodiode or phototransistor (also called photoreceiver UV 30).

The operation of the turbidity device 1 of the invention is therefore based on the known principle of a direct correlation between the service water turbidity degree and the voltage detected to plies of said photoreceiver 30, when hit by the ultraviolet radiation emitted by the phototransmitter 20.

In other words, when wishing to detect the turbidity (or, equivalently, the transparency) degree of the service water of a storage 40, the phototransmitter 20 is suitably fed, which generates an ultraviolet radiation intended to cross said water, and the intensity is measured at the photoreceiver 30, whose value transduced in voltage may be more or less attenuated by the interaction with any suspended particles.

Specific automatic calibration and comparison algorithms, which shall not be discussed any further, thus enable to verify the trend of the transduced measurements and accurately define the service water turbidity level.

According to a first possible embodiment of the invention (not explicitly shown), said emitter 2 and detector 3 of the turbidity device 1 may be part of a single apparatus, for example totally similar (except for any dimensional adaptations within the range of a person skilled in the art) to the known turbidity sensor 1 ’ described above with reference to the state of the art (to which reference is made).

In such case, therefore, the body 10’ of said turbidity sensor L is provided, housed and retained inside a suitably sized and shaped seat 53, on the flange of an electric resistance 5, while the relative appendices 11’, 12’ which house the light emitter 2’ and the detector 3’, protrude therefrom to cooperate with the service water of the storage 40.

Alternatively, nothing prevents the turbidity device 1 of the invention from comprising and providing for the cooperation of at least a first and second body 21, 31 distinct and separate from each other, one adapted to accommodate said light emitter 2, the other the detector 3.

Preferably, said bodies 21, 31 are integrated and fixed to the electric resistance 5, normally used in the storages 40 for heating the water, e.g., inserted respectively on a first and second seat 53. a, 53. b of the flange 50.

Once installed on the flange 50 of the electric resistance 5, said bodies 21, 31 substantially have such a setup as to extend, towards the inside of the storage 40 and ensure, for the reasons that will be further illustrated and/or detailed below, an optimal contact with the service water.

More precisely, said bodies 21, 31 are parallelly arranged flanked and suitably spaced in order to define a space “S”, referred to as "measurement", which may be filled by a volume of water that may be used for determining the turbidity level.

Preferably, said bodies 21, 31 may consist of a pair of capsules 21, 31, for example of cylindrical geometry, one containing the phototransmitter 20, the other the photoreceiver 30, mutually "facing" towards said measurement space S. As shown by way of an example in figure 4a-4b and 5a-5b, said capsules 21, 31 comprise:

- at least one part transparent to the ultraviolet radiation generated by the phototransmitter 20 and/or intercepted by the photoreceiver 30, said part being preferably the one intended to be immersed or in direct contact with the service water, at least in operating conditions, and/or located at said phototransmitter 20 and photoreceiver 30,

- a section 210, 310 for the connection to electrical connectors 22, 32, and/or for the passage of cables (variant not shown), for powering said phototransmitter 20 and photoreceiver 30.

Nothing prevents said capsules 21, 31 from being totally transparent to the ultraviolet radiation so as to allow a freer positioning of said phototransmitter 20 and photoreceiver 30 therein, for example when advantageously mounted on dedicated printed circuits (or PCBs) 23, 33.

It is also known that the storages 40 of service water may be subject to the risk of proliferation of bacteria, viruses and pathogenic germs.

Sanitising devices, such as ultraviolet generators (or similar equipment), capable of reducing or eliminating the virologic and/or bacterial load possibly present in the water have been progressively integrated on said storages 40 (e.g., in the supply/delivery piping and/or on the inner walls thereof) in order to limit such drawback.

According to the invention, it has therefore been found advantageous to use the aforementioned ultraviolet phototransmitter 20 of the turbidity device 1 also as a sanitising device.

In other words, it is possible to activate the turbidity device intermittently and/or for short time intervals (e.g., in the order of milliseconds) when the turbidity level of the service water is wished to be measured, while its operation may be extended for a longer time (for example, in the order of ten minutes) and/or continuously (or by a high “duty cycle'' pulses of) if a sanitising effect on the service water is desired.

Such choice involves numerous advantages compared to state-of-the-art sanitisation devices, in particular the possibility of integrating and implementing a plurality of functions in a single device, consequently reducing the number of components and accessories necessary for the purposes and lowering the production, marketing and maintenance costs.

Furthermore, since the turbidity device 1, as seen, is directly integrated with the electric resistance 5, an optimal interaction with the service water is always ensured even when operating in "sanitising mode". This eliminates the risk that the ultraviolet turbidity device 1 of the invention directly irradiates any plastic parts of the same storage 40 (or of other components of the household appliance), reducing the known consequences deriving therefrom (in particular an ageing and wear acceleration).

It is further specified that the activation of the turbidity device 1 of the invention both for the detection of turbidity of service water and for the possible sanitisation thereof may be delegated to specific electromechanical selectors (for example, the classic knobs or buttons of a user interface) and/or automatically to the electronic control unit with which each household appliance is normally equipped.

When in "sanitising mode", the operation of the device 1 of the invention may for example be related to the presence of water inside the storage 40 of the household appliance 1 and/or its temperature, through dedicated algorithms or logics.

For such purpose, the phototransmitter 20 of the turbidity device 1 may cooperate and use at least one temperature sensor 6 preferably integrated and housed inside the relative capsule 21.

As shown in figure 4b, said temperature sensor 6 may consist, without any limiting intent, of an NTC sensor or any other system capable of detecting and/or controlling:

- the service water temperature inside the storage 40 so as to activate the phototransmitter 20 in "sanitising mode", for example when the detected temperature is lower than a threshold value (e.g. 60 °C) below which there is a non-negligible risk of development and proliferation of bacteria, viruses or pathogens (for water temperatures higher than said threshold, sanitisation occurs spontaneously without the need of activation of the sanitising device 6), and/or

- when said "sanitising mode" is already in operation, the temperatures reached by said one or more UV lamps or LEDs 200 of the phototransmitter 20 so as to identify any anomalies and/or excessive overheating, indicative of potential failures and malfunctions (e.g., due to a short circuit and/or due to excessive wear or end of life).

For such purposes, said at least one temperature sensor 6 may be advantageously installed in the proximity of said one or more UV lamps or LEDs 200 of the phototransmitter 20 of the turbidity device 1 so as to ensure a reliable measurement of the temperatures around them and an acceptable accuracy in any measurement of the service water temperatures.

Of course, nothing prevents using said at least one temperature sensor 6 also to "drive" the electric resistance 5 for heating the service water, acting as or replacing, in fact, the well-known and traditional temperature probes used up to now.

In other words, said at least one temperature sensor 6 may also be used only for the thermostating of the service water, i.e. for the activation and deactivation of the electric resistance 5 of the storage 40.

Summarising, it therefore appears clear that the turbidity device 1 according to the present invention has as a primary function that of determining the turbidity level of the service water contained in a storage 40 and how it may further implement accessory functions such as:

- the sanitisation of said service water from bacteria, viruses and/or germs, or

- the control and management of the temperature of said service water, or

- a combination thereof.

According to some embodiments and/or particular applications and uses, the turbidity device 1 of the invention may meet further accessory/supplementary functions, such as, by way of a non-limiting example:

- the verification of the presence or not of service water inside the storage 40 and/or its level, and/or

- the control and management of the presence and limescale formation within said storage 40 and/or on functional components thereof.

Such accessory/additional functions that may be implemented by the turbidity device 1 of the invention, shall extensively be referred to during this description. For a better operation of the turbidity device 1 of figure 3a-3b, the aforementioned capsules 21, 31 of the emitter 2 and of the receiver 3 are preferably made of glass or quartz glass, since, as known, it is a particularly suitable material adapted to be crossed by both low-frequency light and ultraviolet radiation.

In addition, quartz has physical characteristics suitable for the possible presence and use of the aforementioned one or more temperature sensors 6 for the control of abnormal overheating of the phototransmitter 20 and/or for the measurement of the service water temperatures in the storage 40.

It is in fact known how quartz glass is characterised by a high thermal conductivity and at the same time by a high electrical resistivity and how it is able to electrically insulate the turbidity device 1 of the invention from the support whereon it is mounted, for example, from the flange 50 of the electric resistance 5, without prejudice to its good resistance to ultraviolet radiation.

Quartz glass therefore ensures greater precision and reactivity in reading and monitoring the service water temperatures of the storage 40 compared to steel and plastics, when such function is implemented by the device 1 of the invention and is possibly activated.

Having dealt with the invention in its more general aspects, a possible application thereof is now described, i.e. without any limiting intent, on a washing machine 4 (such term also means similar household appliances such as the so-called "washer-dryers").

As shown in figure. 6, like the solutions of the state of the art, the immersion electric resistance 5, comprising the turbidity device 1 of the invention, may be positioned on the tank 40 of the washing machine 4.

Said tank 40 defines the previously mentioned storage and the drum 41 rotates inside it wherein the clothes and laundry to be washed are loaded through a relative porthole 42.

By way of an example, the electric resistance 5 of the invention may be installed at a first housing 402 obtained on a wall of the tank 40, e.g. the rear one 400. p, and in the proximity of the bottom 400, arranged with the hydraulic unit 7 for draining the water at the end of each step and/or washing process.

Nothing prevents the possibility of positioning such electric resistance 5 directly on said bottom 400 of the tank 40.

The positioning of said electric resistance 5 and of the relative turbidity device 1 near or in correspondence of the bottom wall 400 of the tank 40 is that which ensures constant contact with the service water, at least during the washing and rinsing steps, when they are completely immersed therein.

This allows a correct measurement of the turbidity level of the washing and/or rinsing water while when the turbidity device 1 is used in "sanitising mode" it eliminates the risk that the inner walls of the tank 40 (or other functional components), increasingly made of plastic material, are hit and exposed to ultraviolet radiation, the cause, as known, of their rapid ageing or degradation.

As anticipated in part, also with reference to the field of washing machines 4 (or similar washing machines), the turbidity device 1 of the invention, managed by the control electronics of the machine, may at least:

- carry out its turbidity "reading" and/or sanitising function of the washing water (with relative monitoring of any overheating of its ultraviolet transmitter 20) during, for example, the typical washing and rinsing steps, and/or

- act as a temperature probe during the heating and thermostating steps of said washing water, for example by driving the activation/deactivation of the electric resistance 5.

It should be noted that only the functional components of the washing machine 4 have been described for the purposes of the invention. All the other elements thereof not directly related to the object of the invention, but well known to a person skilled in the art (for example the motor and the relative transmission members for the rotation of the drum 41 such as pulleys 44 and straps 45, ballasts and shock absorbers inside the body, the gaskets, the user interface and the electronic control unit, etc.), were therefore voluntarily dropped. It is clear that numerous variants of the device 1 described above are possible for the person skilled in the art, without thereby departing from the novelty scopes of the inventive idea, just as it is clear that in the practical implementation of the invention the various components previously described may be replaced by technically equivalent elements.

For example, all of the above with reference to the aforementioned washing machine 4 may be extended to any other type of household appliance comprising an inner storage for the service water, such as dishwashers, both domestic and industrial, heat pumps or storage water heaters.

Furthermore, from laboratory tests it has been found that the turbidity device 1 of the invention, described above in its many executive and functional embodiments, may be used, as it is or with small adaptations within the reach of the person skilled in the art, for the verification of the presence or not of service water in a storage 40.

In other words, the turbidity device 1 of the invention may, in fact, replace and get around the traditional level sensors used up to now (see, for example, the known solution of the document of the state-of-the-art WO 2014/0088442).

More precisely, it has been seen how the high frequency of the ultraviolet radiation emitted and managed by the turbidity device 1 allows verifying the presence or not of the service water between its phototransmitter 20 and the relative photoreceiver 30 (i.e. in the aforementioned measurement space S).

This is particularly important because it allows understanding indirectly if the electric resistance 5, whereon the turbidity device 1 is installed, is working "dry", i.e. in a particularly unfavourable and dangerous condition for its efficiency, reliability and duration.

Said function may advantageously use the discontinuity and/or the significant differences (and possibly a relative comparison thereof) in the measurements carried out by the turbidity device 1 in conditions of sufficient presence of water or in total absence thereof.

Nothing prevents such evaluation from being equivalently carried out by controlling the temperature variations inside the storage 40 in the presence or absence/shortage of water, thanks to one or more temperature sensors 6 that the turbidity device 1, as seen, may be equipped with.

Said turbidity device 1 also allows activating and controlling the relative electric resistance 5 for heating the service water in total safety, i.e. without the risk of "dry" operation thereof.

This allows implementing procedures and/or washing steps on said washing machines (or similar) that involve the use of minimum quantities of water, such as for example, in vapour washing cycles (e.g., provided for in some washing machines 4 or washer-dryers), as the level of said water may be kept constantly under control and the operation of the resistance 5 immediately interrupted or suspended if such level falls below a safety threshold (a phenomenon that may not be excluded a priori for said cycles and steps using modest quantities of water).

With the turbidity device 1 of the invention and the relative electric resistance 5 which integrates it, the stated objects are therefore achieved; in particular, it is possible to implement a plurality of functions in a single immersion type device such as:

- the reading of the turbidity level of the water so as to "manage" more effectively the various steps and operations of the washing procedures of the washing machines (washing machines/washer-dryers and/or dishwashers) or the preparation and distribution to the utilities of domestic hot water in the case of water heater; and/or

- the sanitisation of said service water from bacteria, viruses and/or germs; and/or

- the control and thermostating of the temperature of said service water; and/or

- the activation and/or deactivation of at least one electric resistance 5 of the storage 40, and/or

- the verification of the presence or not of service water at said electric resistance 5; and/or - combinations thereof.

In addition, the use of "ultraviolet" (high frequency) turbidity devices 1 allows a more accurate analysis of the turbidity level of water than it may be achieved with the state-of-the-art sensors normally operating with visible light and/or low frequency light.

Under operating conditions, the turbidity device 1 of the invention would also be advantageously placed in a storage zone 40 characterised by a consistent exchange of water, ensured by the convective motions due to the heating put into place by the electric resistance 5; when operating in "sanitising mode", this may favour a more intense reduction of the bacterial, viral or other pathogen load harmful to health.

The turbidity device 1, as described above in its multiple variants, has positive effects also on the possible formation of limescale on the surfaces in contact with the service water, especially if rich in calcium carbonates.

Laboratory tests have in fact shown how the ultraviolet radiation of said turbidity device 1 may contribute to slow down and/or limit the formation of said calcareous deposits.

In particular, it has been shown that the exposure to the ultraviolet light of said water mainly produces calcite crystals which, being less dense and adherent than other types of calcium carbonate phases, are more easily removable from the surfaces whereon they are deposited, for example from the inner walls of a storage of a household appliance or from the functional components thereof such as the same electric resistances.

I.e., there would be a strong mitigation of calcareous encrustations on said surfaces and/or components and, consequently, of the technical problems that may arise in terms of heat transfer, anomalous energy consumptions and frequency of maintenance interventions.

At the same time, at least in some of the construction variants and/or applications thereof, the turbidity device 1 of the invention may be able to identify the possible formation of said calcareous deposits inside the storage 40 of the household appliance, in particular at the electric resistance 5 thereof, and consequently report the need of:

- starting descaling cycles that may be managed by the electronics of the household appliance and generally using acid products, and/or, especially in the most critical cases,

- suggesting actual maintenance interventions by the technical assistance for the removal of calcareous deposits and/or for the radical replacement of the encrusted component.

Usually, the limescale deposit that affects an electric resistance is difficult to detect with the traditional control and monitoring systems/devices and therefore it is noticeable only when the operation of that component is compromised.

This problem may be overcome by means of the turbidity device 1 of the invention.

In fact, as seen, in one preferred embodiment thereof, said turbidity device 1 is installed directly on the electric resistance 5 and therefore the possible formation of limestone thereon may also involve the same turbidity device 1.

In particular, a substantial opacification of one or both of the bodies 21, 31 of the turbidity device 1 which house, respectively, the emitter 2 of light radiation and the corresponding detector 3, may be observed.

Such opacification may lead to an attenuation of the intensity of the light radiation intensity emitted by the emitter 2 and detectable by the corresponding detector 3.

For such purpose, the control of any calcareous deposit on the electric resistance 5 is preferably carried out when there is the reasonable certainty that possible attenuations of the intensity of said light radiation is exclusively attributable to the opacification (or similar phenomena) of the aforementioned bodies 21, 31 of the turbidity device 1 of the invention and not by other factors, e.g. due to the presence of those particles suspended in the service water that may alter the transparency thereof.

For example, with reference to the sector of washing machines 4, washer-dryers or similar washing machines, said detection of hmescale deposits may be carried out as soon as the first load of washing water in tank 40 is finished (which, in fact, is assumed to be substantially free from such suspended particles or in any case in negligible quantities), i.e. before the drum 41 containing the load of dirty laundry to be washed is moving.

Alternatively, the extent of such phenomenon may be controlled, substantially with the same results, even at the end of a rinsing cycle as excessive turbidity conditions in the residual washing water are unlikely.

Finally, nothing prevents the provision of a further executive variant of the invention, according to which the emitter 2 of light radiation, in addition to comprising an ultraviolet generator or phototransmitter 20, also integrates an infrared or visible light LED or lamp.

According to this variant, therefore, the following will be activated:

- only the ultraviolet phototransmitter 20, for example, the specific UVC LED 200, when the turbidity device 1 of the invention will be operated in sanitising mode,

- the only visible or infrared light LED or lamp (for example, with a wavelength of about 870 nm) when the measurement of the water turbidity in the storage 40 is required (which, as seen, represents one of the main functions) and/or the execution of one or more of the additional accessory/supplementary functions described above, such as measuring the water level and/or the temperature thereof, the verification of possible formation of calcareous deposits, etc.,

- both the ultraviolet phototransmitter 20 and the infrared LED or lamp, when it is required that two or more of the above functions are performed simultaneously and/or in succession.

Given the possibility of using visible light for detecting the degree of turbidity and/or for further accessory/supplementary functions, the UV photoreceiver 30 of the detector 3 of the turbidity device 1 may therefore be placed side by side and/or replaced by a simpler and economical infrared phototransistor. In such case, while the capsule 21 containing, as seen, the emitter 20 may still be made of quartz glass, the capsule 31 of the detector 3 is instead preferably made of silicate glass since:

- being transparent to infrared radiation (or, in general, visible), allows correct and effective operation of the turbidity device 1 of the invention when used for the measurement of the turbidity (and/or for implementing the aforementioned accessory/supplementary functions),

- it protects the detector 3, and relative components, when the turbidity device is operating in sanitising mode by blocking the ultraviolet radiation.

In addition, the integration of the turbidity device 1 on the electric resistance avoids the need of providing for specific arrangements or modifications to the structure of the storage and/or to the basic components of the relative appliance. For example, no additional and dedicated gasket will be provided, as required instead to seal the installation site of traditional turbidity sensors that may be mounted on a wall of a storage, nor will specific compartments and/or housings be defined in such storage for the positioning thereof.

Finally, it is noted that the installation of the electric resistance of the invention comprising the turbidity device 1 does not require additional attention and/or precautions other than those normally provided for a traditional resistance; this allows retrofitting and upgrading operations on household appliances already on the market and/or used, or the replacement of said traditional electric resistances with that of the invention without the need to redesign the household appliance and/or structural changes to the relative storage (or other parts).

In conclusion, in the light of the above, the advantages of management, assembly, footprint and reduction of production and maintenance costs, compared to the solutions currently used, which may be achieved with the turbidity device 1 of the invention and the relative electric resistance 5, are therefore evident.