Technical Field

The present invention relates to a device for the treatment of water.

Background Art

As is well known, the expression “treatment of water” usually means the control and correction of some of the chemical-physical and bacteriological characteristics of a water stream for the purpose of using and/or reusing the latter in one or more different applications.

For this purpose, the devices for the treatment of water adapted to add a relevant chemical additive to the water stream to be treated are generally used so as to make it suitable for the desired purpose.

In fact, such devices can be used to reduce the amount of bacteria and/or contaminants contained in a water stream, so as to bring the latter into compliance with the increasingly stringent current sanitation regulations, thus making its use biologically safe.

By doing so, the treated water can, e.g., be used in normal household consumption, swimming pools, field irrigation, the industrial sector (e.g., in food plants) and other application situations still.

One particular type of devices for the treatment of water known to date comprises: a hollow main body connectable to a chemical additive tank and defining an inner chamber provided with an inlet opening of a water stream to be treated and an outlet opening of a treated water stream; pumping means adapted to pick up the additive from the tank and feed it into the inner chamber; and actuating means of the pumping means.

Specifically, the pumping means comprise at least one pumping piston movable alternately along one direction of pumping to pick up the additive from the tank, and the actuating means comprise at least one actuating chamber within which an actuating piston is housed movable alternately along one direction of actuation and mechanically connected to the pumping piston.

The known devices are then provided with valve means adapted to selectively convey the water stream to be treated from one side of the actuating piston to the other so as to vary the way of the thrust exerted thereon and thus give it the aforementioned alternating motion.

The actuating piston has, therefore, the role of a motor piston and allows, as a result of the thrust exerted thereon by the water stream, to drag the pumping piston in motion which, on the other hand, is adapted to suck and send the additive into the inner chamber due to its own alternating motion.

In this way, the additive is conveyed within the main body and ends up mixing with the water stream to be treated.

In known treatment devices, the above-described valve means are built into the actuating piston which, at each end of the stroke, actuates the valve means themselves thanks to its alternating motion and, in so doing, allows the stream of water to flow into the opposite chamber.

Specifically, the actuation of the valve means occurs as a result of the interaction of the latter with the upper and lower bottom walls, which bound the chamber within which the actuating piston moves.

In this way, that is, by varying the side of the actuating piston with respect to which the stream of water is conveyed, it is clearly possible to reverse the way of the force impressed by the latter on the actuating piston itself and thus to obtain the mentioned motion of the pumping means.

That said, it is important to explain that the treatment devices described so far suffer from some drawbacks and are, therefore, amenable to various refinements. First of all, the treatment devices of known type require the actuating piston and the pumping piston to work coaxially; therefore, even slight misalignments between the two can result in dangerous rubbing of them against the walls of the inner chamber and, consequently, their damage and early end-of-life.

Second, it is worth mentioning that the operation of the valve means described above proves to be particularly noisy in practice due to the interaction with the bottom walls of the chamber within which the actuating piston slides.

What is more, due to their particular arrangement within the first piston, the maintenance of such valve systems is very laborious to perform, resulting in the need for significant economic resources and long service times.

Description of the Invention

The main aim of the present invention is to devise a device for the treatment of water which is silent, easy to maintain and marked by a low wear and tear rate of its parts.

Another object of the present invention is to devise a device for the treatment of water which can overcome the aforementioned drawbacks of the prior art within the framework of a simple, rational, easy and effective to use, as well as cost- effective solution.

The aforementioned objects are achieved by this device for the treatment of water having the characteristics of claim 1.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become more apparent from the description of a preferred, but not exclusive, embodiment of a device for the treatment of water, illustrated by way of an indicative, yet nonlimiting example, in the accompanying tables of drawings in which:

Figure 1 is an axonometric, overall view of the device according to the invention; Figure 2 is a front cross-sectional view of the device according to the invention in a first operational configuration;

Figure 3 is an axonometric, cross-sectional view showing the transition from the first operational configuration to a second operational configuration;

Figure 4 is a front cross-sectional view of the device according to the invention in the second operational configuration;

Figure 5 is an axonometric, cross-sectional view showing the transition from the second operational configuration to the first operational configuration;

Figure 6 is a top cross-sectional view of the device according to the invention. Embodiments of the Invention

With particular reference to these figures, reference numeral 1 globally denotes a device for the treatment of water.

The device 1 for the treatment of water first comprises at least one hollow body 2 defining at least one internal volume 3, 4, 5 and provided with at least one inlet port 6 of the water to be treated W 1 and with at least one outlet port 7 of treated water W2.

It is specified, in this regard, that the expressions “water to be treated” and “treated water” refer to a stream of water having microbiological profile and contaminant density such as to make it unsuitable/suitable for use, respectively, in one or more technical applications such as, e.g., in normal household consumption, swimming pools, field irrigation, industrial sector (e.g., in food establishments), and so on.

Having specified all this, the internal volume 3, 4, 5 comprises: at least one actuating chamber 3; at least one mixing chamber 4 communicating with the outlet port 7; and at least one distribution volume 5 communicating with the inlet port 6 and with the mixing chamber 4, where the distribution volume 5 is arranged alongside the actuating chamber 3 and communicating therewith.

In this case, in accordance with the preferred embodiment, the mixing chamber 4 is arranged to surround the actuating chamber 3 and the distribution volume 5 (see Figure 6 in this regard).

According to the particular embodiment shown in the figures, the distribution volume 5 has an elongated shape.

More precisely, the distribution volume 5 has a substantially right cylinder conformation.

In this regard, the distribution volume 5 is communicating with the mixing chamber 4 at the longitudinal ends 2 la, 2 lb thereof (i.e., the faces of the cylinder). As visible in Figure 3 and Figure 5, the distribution volume 5 comprises at least a first communication hole 24a with the mixing chamber 4 at a first longitudinal end 21a, and at least a second communication hole 24b at a second longitudinal end 21b.

Precisely, the distribution volume 5 comprises a plurality of first communication holes 24a and a plurality of second communication holes 24b.

Conveniently, the distribution volume 5 has at least one first port 22 and at least one second port 23 communicating with the actuating chamber 3. Specifically, the first port 22 is arranged, in use, above the second port 23.

Advantageously, the device 1 comprises at least a first lateral containment wall 25 a of the distribution volume 5 and at least a second lateral containment wall 25b of the actuating chamber 3.

In the present case, the containment walls 25 have a substantially cylindrical conformation and have at least one common portion 26, the first port 22 and the second port 23 being defined on the common portion 26.

In other words, the distribution volume 5 and the actuating chamber 3 are contiguous with each other.

This fact, together with the arrangement of the mixing chamber 4 to surround the distribution volume 5 and the actuating chamber 3, makes it possible to greatly reduce the overall dimensions compared with known devices, thus making a particularly compact device 1.

Having described the internal volume 3, 4, 5, the device 1 comprises at least one pumping assembly 9 communicating with the mixing chamber 4 and connectable to a tank containing the additive Y to be mixed with the water to be treated W 1 to obtain the treated water W2.

In the present case, the pumping assembly 9 comprises at least one pumping piston 10 movable alternately along one direction of pumping P to take the additive Y from the tank and transfer it to the internal volume 3, 4, 5.

Precisely, the alternating motion of the pumping piston 10 causes the additive Y to be picked up from the tank and transferred to the mixing chamber 4.

In this regard, the hollow body 2 comprises at least one pick-up end 11 which defines a pick-up cavity 12 communicating with the mixing chamber 4 and within which the pumping piston 10 is movable alternately.

Specifically, the pick-up end 11 is adapted to be inserted into the tank so that the pumping piston 10 is allowed to pick up the additive Y from the tank and convey it into the internal volume 3, 4, 5.

As visible from the figures, the pick-up end 11 has an elongated conformation. Specifically, the pick-up cavity 12 develops substantially aligned with the direction of pumping P. As mentioned, the pumping piston 10 is movable in the pick-up cavity 12; specifically, it is movable between a pick-up position, wherein it is maximally inserted in the pick-up cavity 12, and a loading position, wherein it is minimally inserted in the pick-up cavity 12.

Concretely, the pick-up position corresponds to the bottom dead center of the stroke of the pumping piston 10 within the pick-up cavity 12, while the loading position corresponds to the top dead center of the stroke of the pumping piston 10 within the pick-up cavity 12.

As will become clearer shortly, the alternating motion of the pumping piston 10 between the aforementioned positions allows the additive Y to be pumped from the tank to the pick-up cavity 12 and, consequently, to be fed into the mixing chamber 4, where it can mix with the water to be treated Wl.

Conveniently, the pumping assembly 9 comprises sealing means 13 associated with at least one of either the pumping piston 10 or the pick-up cavity 12 and adapted to: subdivide the pick-up cavity 12 into a first volume 12a communicating, in use, with the tank and into a second volume 12b communicating with the mixing chamber 4; and to allow/prevent the transit of the additive Y from the first volume 12a to the second volume 12b when the pumping piston 10 moves from the loading/pick-up position to the pick-up/loading position.

In other words, the sealing means 13 allow the additive Y to flow from the first volume 12a to the second volume 12b when the pumping piston 10 moves from the top dead center to the bottom dead center, while they prevent this flow, obstructing the transit, when the pumping piston 10 moves from the bottom dead center to the top dead center.

To appreciate the advantages achieved by the sealing means 13 it is appropriate to explain in more detail how pumping occurs of the additive Y by the pumping piston 10.

In this regard, it should be considered that the transit of the pumping piston 10 from the pick-up position to the loading position results in a decrease in the pressure in the pick-up cavity 12, which leads to the sucking out of the tank of a certain amount of additive Y and to the introduction thereof into the first volume 12a.

During the subsequent stroke of the pumping piston 10 (i.e., in its transition from the loading position to the pick-up position, that amount of additive Y passes through the sealing means 13 and flows, in so doing, from the first volume 12a to the second volume 12b.

At the still subsequent stroke of the pumping piston 10 (i.e., in its transition from the pick-up position to the loading position, the additive Y flowed into the second volume 12b is pushed by the pumping piston itself towards the mixing chamber 4, thus eventually mixing with the water to be treated W1 present there.

With this in mind, note that the sealing means 13 prevent the additive Y in the second volume 12b from flowing back into the first volume 12a during the stroke of the pumping piston 10 from the loading position to the pick-up position, thus allowing the pumping assembly 9 to operate efficiently.

In actual facts, it can be inferred from what has been said so far that the operation of the pumping assembly 9 is substantially similar to that which distinguishes pressure pumps.

In accordance with the preferred embodiment shown in the figures, the sealing means 13 comprise at least one sealing element 14 inserted in a respective seat 15 formed perimeterwise around the pumping piston 10.

It is specified that, preferably, the sealing element 14 is a gasket of the type of an O-ring.

Conveniently, the seat 15 is formed on one end of the pumping piston 10.

Detailing the seat 15 more, it is important to specify that its extension along the direction of pumping P is greater than the thickness of the sealing element 14. This means that the sealing element 14 is inserted into the seat 15 with some axial clearance and, therefore, it moves within the seat 15, sliding along the direction of pumping P, during the movement of the pumping piston 10.

More precisely, the sealing element 14 moves in a first way of the direction of pumping P as a result of the transition of the pumping piston 10 from the pick-up position to the loading position, while it moves in a second way of the direction of pumping P at the transition of the pumping piston 10 from the loading position to the pick-up position.

In this regard, the sealing means 13 comprise at least one pass-through slot 16a, 16b of the additive Y formed on the pumping piston 10 and developing along a direction substantially parallel to the direction of pumping P.

In the present case, the pass-through slot 16a, 16b has a first section 16a obtained within the seat 15 and a second section 16b, contiguous to the previous one, facing the second volume 12b (see magnifying views in Figure 3 and in Figure 5 in this regard).

In actual facts, the first section 16a is contained within the seat 15, while the second section 16b towers above it.

In the case where the pumping piston 10 moves from the pick-up position to the loading position, therefore, the sealing element 14 is arranged against the lower walls of the seat 15 and, by sealing against the surface of the pick-up cavity 12, prevents the additive Y contained in the first volume 12a from accessing the first section 16a and, therefore, the second volume 12b (Figure 3).

In the case where, on the other hand, the pumping piston 10 moves from the loading position to the pick-up position, the sealing element 14 is arranged against the upper walls of the seat 15 thus allowing the additive Y contained in the first volume 12a to pass through the pass-through slot 16a, 16b and to flow within the second volume 12b (Figure 5).

The arrangement of the sealing element 14 against the lower/upper walls of the seat 15 substantially prevents/allows the additive Y sucked into the first volume 12a to pass through the pass-through slot 16a, 16b and, therefore, to flow into the second volume 12b.

As previously mentioned, this expedient enables the pumping assembly 9 to effectively convey the additive Y from the tank to the mixing chamber 4, thus allowing it to be mixed with the water to be treated Wl.

Conveniently, the pumping assembly 9 comprises retaining means 17 arranged in the first volume 12a and adapted to prevent the reflux of the additive Y from the latter to the tank in the transition of the pumping piston 10 from the loading position to the pick-up position.

In accordance with the embodiment shown in the figures, the retaining means 17 are of the type of one or more check valves.

Thus, the combination of the sealing means 13 and the retaining means 17 ensures that, upon the transition of the pumping piston 10 from the loading position to the pick-up position, the additive Y present in the first volume 12a can only flow into the second volume 12b, and that, upon the transition from the pick-up position to the loading position, the additive Y conveyed into the second volume 12b can only flow into the mixing chamber 4.

In actual facts, the sealing means 13 and the retaining means 17 work synergistically to ensure that the volume of additive Y picked up from the tank can only flow from the first volume 12a to the second volume 12b and from the second volume 12b to the mixing chamber 4.

In addition, the device 1 comprises actuating means 18 of the pumping assembly 9 which are housed in the actuating chamber 3 and comprising at least one actuating piston 18.

In detail, the actuating piston 18 is movable alternately along a direction of actuation A and is mechanically connected to the pumping piston 10.

Preferably, the direction of actuation A is substantially parallel to the direction of pumping P.

As visible in the figures, the direction of actuation A is substantially aligned with the direction of pumping P.

It should be pointed out that the expression “substantially aligned” encompasses, in this case, not only the actual perfect alignment between the direction of actuation A and the direction of pumping P, but also the possibility that they may deviate from this ideal condition by an angle comprised between -1° and +1°. Specifically, the actuating piston 18 moves between two end-of-stroke positions located between the first port 22 and the second port 23, of which one is the lower end-of-stroke position and one is the upper end-of-stroke position.

In other words, the actuating piston 18 is positioned between the first port 22 and the second port 23.

In this regard, the device 1 comprises interconnection means 19 of the actuating piston 18 with the pumping piston 10.

Conveniently, the interconnection means 19 have at least two degrees of freedom. Specifically, the two degrees of freedom correspond to the ability of the pumping piston 10 to move with respect to the actuating piston 18 along directions which are substantially orthogonal to each other.

More specifically, the aforementioned directions are substantially orthogonal to the direction of pumping P.

It is worth highlighting how this technical expedient allows for the proper operation of the device 1 even with slight misalignments between the pumping piston 10 and the actuating piston 18, averting the risk of dangerous rubbing between the pumping piston 10 and the walls of the pick-up cavity 12.

In this sense, it is easy to appreciate how providing interconnection means 19 makes it possible to obtain a device 1 which is considerably more functional than known devices and distinguished, compared with the latter, by a significantly lower rate of wear and tear on its components.

In the particular embodiment shown in Figures 2 to 5, the interconnection means 19 comprise: at least one fastening tang 19a associated with one of either the pumping piston 10 or the actuating piston 18; and at least one housing 19b of the fastening tang 19a made on the other of either the pumping piston 10 or the actuating piston 18.

In the present case, the fastening tang 19a is associated with the pumping piston 10 and the housing 19b is made on the actuating piston 18.

Specifically, the fastening tang 19a is obtained on the end of the pumping piston 10 opposite that on which the seat 15 is formed.

The fastening tang 19a is, therefore, inserted into the housing 19b with the possibility of moving with respect thereto along the aforementioned directions which are orthogonal to the direction of pumping P, allowing the aforementioned advantages related to less wear and tear of the components of the device 1 to be achieved compared to the devices of the mentioned state of the art.

It is important to highlight at this point that the actuating piston 18 divides the actuating chamber 3 into a first chamber 3a and into a second chamber 3b. Specifically, the first chamber 3 a is arranged, in use, above the second chamber 3b.

In this regard, the first port 22 is communicating with the first chamber 3a, while the second port 23 is communicating with the second chamber 3b.

Conveniently, the device 1 comprises valve means 20 adapted to selectively set the inlet port 6 in communication with the first chamber 3a and with the second chamber 3b so as to alternately move the actuating piston 18 within the actuating chamber 3.

In other words, the valve means 20 allow the water to be treated W1 to be selectively conveyed to one side and to the other side of the actuating piston 18 so as to exert forces on the latter having a direction parallel to the direction of pumping P and a way opposite each other allowing the alternating motion thereof. Specifically, if the valve means 20 set the inlet port 6 in communication with the first chamber 3a, then the water to be treated W1 generates a force pushing the actuating piston 18 downwards, bringing the pumping piston 10 towards the pickup position.

Similarly, if the valve means 20 set the inlet port 6 in communication with the second chamber 3b, then the water to be treated W 1 generates a force pushing the actuating piston 18 upwards, bringing the pumping piston 10 towards the loading position.

According to the invention, the valve means 20 comprise at least one distributor 20 housed sealed in the distribution volume 5 so as to insulate an inlet chamber 8 communicating with the inlet port 6.

In this regard, to state that the distributor 20 insulates an inlet chamber 8 communicating with the inlet port 6 is to mean that the same defines in the distribution volume 5 a portion, corresponding to the inlet chamber 8, communicating with the inlet port 6 in a fluid-operated maimer and intended to be filled with the water to be treated W 1 during the operation of the device 1. From what has been described so far, it is already possible to appreciate that, in contrast to the prior art, the valve means 20 in question are physically separated from the actuating piston 18 and their access from the outside is, as a result, considerably easier, to the obvious benefit of the simplicity and rapidity of maintenance of the device 1.

In detail, the distributor 20 is movable along a direction of distribution D.

Specifically, the direction of distribution D is substantially parallel to the direction of actuation A.

This means that the direction of distribution D is substantially parallel to both the direction of actuation A and the direction of pumping P.

Going into more detail, the distributor 20 is alternately movable along the direction of distribution D between a first working position, wherein it sets the inlet chamber 8 in communication with the first chamber 3 a and the second chamber 3b with the mixing chamber 4, and a second working position, wherein it sets the inlet chamber 8 in communication with the second chamber 3b and the first chamber 3 a with the mixing chamber 4.

Depending on the position in which the distributor 20 is located, therefore, the water to be treated W 1 contained in the inlet chamber 8 flows either into the first chamber 3a or into the second chamber 3b, thus exerting a downward or upward thrust force on the actuating piston 18, respectively.

Specifically, in the first working position, the distributor 20 sets the inlet chamber 8 in communication with the first port 22, insulating it from the second port 23, and sets the latter in communication with the second longitudinal end 21b (and, therefore, with the second communication holes 24b), keeping the first longitudinal end 21a closed.

Similarly, in the second working position, the distributor 20 sets the inlet chamber 8 in communication with the second port 23, insulating it from the first port 22, and sets the latter in communication with the first longitudinal end 21a (and, therefore, with the first communication holes 24a), keeping the second longitudinal end 2 lb closed.

According to the invention, the device 1 comprises kinematic connecting means 27 between the actuating piston 18 and the distributor 20.

Specifically, the kinematic connecting means 27 are adapted to control the displacement of the distributor 20 between the working positions depending on the position of the actuating piston 18.

In actual facts, the kinematic connecting means 27 place the actuating piston 18 and the distributor 20 in mutual interaction, so that the movement of the former between the end-of-stroke positions affects that of the latter between the working positions and vice versa.

Specifically, the kinematic connecting means 27 are adapted to: displace the distributor 20 towards the second working position as a result of the displacement of the actuating piston 18 towards the lower end-of-stroke position; and to displace the distributor 20 towards the first working position as a result of the displacement of the actuating piston 18 towards the upper end-of-stroke position.

Going into detail, the kinematic connecting means 27 comprise: at least one activating element 28 mechanically connected to the distributor 20 and movable between a raised position, wherein it pushes the distributor 20 towards the first working position, and a lowered position, wherein it pushes the distributor 20 towards the second working position; and elastic means 29 associated, on one side, with the actuating piston 18 and, on the opposite side, with the activating element 28, the elastic means 29 being adapted to: push the activating element 28 towards the lowered position as a result of the displacement of the actuating piston 18 towards the lower end-of-stroke position; and to push the activating element 28 towards the raised position as a result of the displacement of the actuating piston 18 towards the upper end-of-stroke position. As far as the activating element 28 is concerned, it has a first end 28a hinged around an axis of hinge I which is fixed with respect to the hollow body 2. Specifically, the first end 28a is pivoted on a fixed base body 30 located in the mixing chamber 4 and towering above the actuating chamber 3.

Precisely, the first end 28a is pivoted on the base body 30 at a reference height the role of which in the operation of the kinematic connecting means 27 will be clarified shortly.

Again, the axis of hinge I passes through the base body 30 and is substantially orthogonal to the direction of distribution D.

The activating element 28 then has a second end 28b, opposite the previous one, which is connected to the distributor 20.

More specifically, the second end 28b is connected to a connecting element 31 which is associated with the distributor 20.

As visible in Figure 3 and Figure 5, the connecting element 31 has a substantially cylindrical conformation and is arranged substantially orthogonal to the direction of distribution D (i.e., it is positioned so that its length is substantially orthogonal to that direction).

In the particular embodiment illustrated, the activating element 28 is of the type of a rocker arm, that is, a lever hinged at one end (which, in the present case, is identified with the first end 28a hinged on the base body 30 around the axis of hinge I) and movable between only two fixed positions (identified, in the present case, with the raised position and the lowered position).

On the other hand, as far as the elastic means 29 are concerned, they consist of at least one elastically deformable element 29 of the type of a coil spring.

In the particular embodiment shown in the figures, the elastic means 29 consist of two elastically deformable elements 29 arranged at the sides of the activating element 28.

It is easy to appreciate, however, how the number of elastically deformable elements 29 is entirely indicative and may be different from the displayed number and, for example, equal to one or four.

In all cases, the elastic means 29 are hinged to the actuating piston 18 on one side and to the activating element 28 on the other side.

Specifically, they comprise at least a first end portion 29a hinged to the actuating piston 18 and a second end portion 29b hinged to the connecting element 31. In other words, the first end portion 29a moves locked together with the actuating piston 18 along the direction of actuation A, while the second end portion 29b moves locked together with the distributor 20 along the direction of distribution D.

Specifically, the first end portion 29a moves in concordance with the actuating piston 18 along a stretch of the direction of actuation A, the reference height of the first end 28a being positioned along the aforementioned stretch.

This means that the first end portion 29a crosses the reference height, in one way or the other depending on the way of movement of the actuating piston 18, during its own motion along the aforementioned stretch of the direction of actuation A. It is important to explain that crossing the reference height causes the elastic means 29 to deform elastically to such an extent to cause the activating element 28 to tip over from the raised position to the lowered position or vice versa.

Specifically, if the first end portion 29a exceeds the reference height by moving downwards (i.e., at the transition of the actuating piston 18 from the upper end- of-stroke position to the lower end-of-stroke position), then the elastic means 29 cause the activating element 28 to tip over from the raised position to the lowered position.

Similarly, if the first end portion 29a exceeds the reference height by moving upwards (i.e., at the transition of the actuating piston 18 from the lower end-of- stroke position to the upper end-of-stroke position), then the elastic means 29 cause the activating element 28 to tip over from the lowered position to the raised position.

Providing for such kinematic connecting means 27 therefore unties the operation of the distributor 20 from the interaction with the bottom walls of the distribution volume 5, greatly increasing the quietness of the device 1 compared with known devices.

To further clarify how the kinematic connecting means 27 operate on the distributor 20 and on the actuating piston 18 the operation of the device 1 is now disclosed.

As mentioned above, if the activating element 28 is in the raised position and the distributor 20 is, therefore, in the first working position, then the inlet chamber 8 is communicating with the first chamber 3 a, the actuating piston 18 is in the upper end-of-stroke position and the pumping piston 10 is in the loading position.

The water to be treated W1 introduced into the inlet chamber 8 is, therefore, conveyed into the first chamber 3 a, exerting a thrust force on the actuating piston 18 such that it is brought from the upper end-of-stroke position to the lower end- of-stroke position and so as to displace, at the same time, the pumping piston 10 from the loading position to the pick-up position (Figure 2).

At the same time, the water to be treated W 1 that may be present in the second chamber 3b is pushed by the actuating piston 18 through the second port 23 and through the second communication holes 24b ending up, thus, in the mixing chamber 4 (Figure 3).

By doing so, the water to be treated W 1 can mix with the additive Y, become treated water W2 and flow out of the device 1 through the outlet port 7.

At the same time as the movement of these pistons, the height at which the first end portion 29a is located, which is initially greater than the reference height, gradually decreases until it coincides with the reference height itself

After the first end portion 29a has exceeded the reference height, the extent of the deformation of the elastic means 29 causes the latter to determine the activating element 28 to tip over from the raised position to the lowered position.

Consequently, the distributor 20 is moved from the first working position to the second working position, setting the inlet chamber 8 in communication with second chamber 3b and the first chamber 3a in communication with the mixing chamber 4.

This allows the water to be treated W 1 introduced into the device 1 to flow from the inlet chamber 8 to the second chamber 3b and, in doing so, to exert a thrust force on the actuating piston 18, in the opposite way to the previous one, which causes the motion thereof to be reversed (Figure 4).

In this way, the actuating piston 18 moves from the lower end-of-stroke position thus reached to the upper end-of-stroke position.

At this reversal of motion, the water to be treated W1 contained in the first chamber 3a flows through the first port 22 and the first communication holes 24a ending up in the mixing chamber 4 (Figure 5).

In this way, similar to the above, the water to be treated W 1 can mix with the additive Y and become treated water W2 to be sent out to the device 1 through the outlet port 7.

At the same time, the height at which the first end portion 29a is located gradually increases until it reaches and exceeds the reference height, thus causing the activating element 28 to tip over from the lowered position to the raised position. In this way, the distributor 20 is returned to the first working position and the inlet chamber 8 is made communicating with the first chamber 3 a, so that the water to be treated W 1 introduced into the device 1, flowing into the latter, determines the continuous cycle reiteration of the operation just discussed.

It has in practice been ascertained that the described invention achieves the intended objects.

In particular, the fact is emphasized that the special expedient of providing valve means comprising a distributor moving alternately between the two working positions enables the actuating piston and, consequently, the pumping piston to be moved precisely and quietly.

This same expedient, among other things, makes the device according to the invention decidedly easy to maintain since the access to the aforementioned valve means is somewhat simplified compared to the aforementioned state of the art.

Finally, the special expedient of providing interconnecting means with two degrees of freedom significantly reduces the wear and tear rate of the components of the device according to the invention, greatly increasing its operating life compared to known devices.