EP2236454B1

EP2236454B1 - Valve assembly for an isobaric filling machine

Info

Publication number: EP2236454B1
Application number: EP10158221.1A
Authority: EP
Inventors: Giovanni Mazzon; Stefano Stefanello; Gianluca Stella; Renato Fuin
Original assignee: Gruppo Bertolaso SpA
Current assignee: Gruppo Bertolaso SpA
Priority date: 2009-03-31
Filing date: 2010-03-29
Publication date: 2013-09-18
Anticipated expiration: 2030-03-29
Also published as: SI2236454T1; EP2236454A1; IT1393727B1; ITPD20090075A1

Description

The present invention refers to a valve assembly for an isobaric machine for filling containers with liquids.
The valve assembly described is intended to be used in the field of industrial bottling plants, on an isobaric filling machine for filling containers, such as bottles, with pressurised liquids in particular of the food product type, such as sparkling and non sparkling wines, champagne type beverages, mineral water, etcetera.
More in detail, isobaric machines are provided with a support structure on which a rotating turntable (or turret) that supports a tank for containing the liquid to be bottled, is rotatably mounted, below which a plurality of filling valve assemblies are fixed.
The containers lifted by suitable plates are associated with the individual valve assemblies so as to be filled up to the desired level during the operation stroke around the turntable.
For this purpose, each valve assembly is equipped with a tubular duct, which is intercepted by a valve (shutter), which adjusts the flow of liquid, for example wine, from the tank into the container below generally consisting of a bottle arranged coaxially below the valve assembly.
A compensation cannula, through which the gases or air present in the container return, is coaxially mounted inside the tubular duct.
The flow of liquid into the container occurs once the pressure in it is brought to the pressure of the tank. During the filling step, the air present in the container comes out through the compensation cannula or through a hole on the side. Once the step of filling the container is finished, for example through the closing command of the liquid passage valve, the compensation cannula is moved so as to enter with a portion inside the bottle up to the level of liquid which is wished to be set. At this stage, a controlled flow of inert gas is sent inside the container to make the liquid rise through the compensation cannula, determining the automatic levelling in the container.
The container is then brought back to ambient pressure through at least one degassing duct and relative control valve.
Furthermore, some isobaric machines of the known type foresee one or more steps for evacuating the air present in the bottle to reduce the oxygen and therefore the risks of oxidation of the beverage.
Therefore, isobaric machines on the market today have a plurality of valves and of actuators suitable for activating, according to predetermined operation cycles, the supply of liquid into the containers i.e. the control of gas towards and from the container.
For example, an automatic isobaric machine can typically be provided with a gas valve for controlling the vacuum, with a gas valve to bring the pressure in the container to the pressure of the tank, with a gas valve to command the supply of inert gas in the container to define the level of liquid, with a liquid passage valve to control the supply duct of the liquid in the container as well as with a first actuator to command the lowering of the compensation cannula and simultaneously the closing and the opening of the liquid passage valve, and a second actuator to command the closing and the opening of the compensation cannula so as to avoid zeroing the pressure in the tank during the degassing or when there is no container. The state of the art of isobaric filling machines foresees a wide possibility of controlling the operations of a filling cycle (achieving vacuum, filling, automatic levelling, degassing) through adjustment of the operating times of the valves and of the actuators, making it possible to optimise the single operations according to both the speed of the filling machine as well as to the type of product to be bottled. Concerning this, it is particularly desirable in the field of reference to control the level of liquid inside the container with an accurate adjustment.
Currently, the valve for intercepting the liquid opens in an automatic manner overcoming the resistance force of a spring when the pressure in the container reaches the pressure of the tank. After this, once the filling step is finished, the same intercepting valve is forced to close by the lowering of the compensation cannula controlled by the first actuator, which during a first portion of the lowering overcomes the resistance of the spring bringing the valve back into the closed position and during a subsequent and further portion of the lowering brings the compensation cannula to the desired depth in the container to obtain the levelling of the liquid.
In order to allow the intercepting valve to open in the subsequent filling cycle, the compensation cannula must completely rise back up moved by the first actuator since even a small pressure on the intercepting valve would not allow it to open. The stroke of the compensation cannula in current isobaric machines is at most 40-45 mm and takes into account different possible container formats. For this purpose, an adjustment ring is foreseen that acts as a check for the adjustment of the level of penetration of the compensation cannula inside the container.
The opening of the valve for intercepting the liquid is obtained with the end part of the rising stroke of the compensation cannula.
Since at every cycle it is obviously necessary to open the valve for intercepting the liquid to fill the container below, it is at the same time equally necessary at each cycle to completely lift the compensation cannula making it run the entire stroke inside with respect to the intercepting valve.
This is usually obtained with a tubular shutter, which is defined outside by a sleeve with which it defines a supply duct of the flow of liquid from the tank to the container. Inside the tubular shutter the compensation cannula is coaxially inserted on which through two or more gaskets a liquid seal is foreseen so as to avoid that during operations of liquid levelling the over-pressure in the container with respect to the tank can drain off passing between the compensation cannula and the tubular shutter.
During its cyclical lowering, the compensation cannula is accompanied in the first portion by the tubular shutter until it is made to close the supply duct of the liquid and, for the remaining portion, much greater with respect to the first and extending so as to take into account the different possible adjustments of the level even of 40 mm, slides with respect to the tubular shutter causing, in the current isobaric machines present on the market of the type described above, a rapid wearing and deterioration of the sealing gaskets.
The wearing encountered with adjustment strokes of 40 mm makes it impossible to think of increasing such a stroke so as to allow adjustments of the level in the container within wider ranges.
Moreover, in isobaric filling machines present on the market today the closing of the intercepting valve depends upon the lowering of the compensation cannula, which limits the operative possibilities of the machine.
A rotary filling machine is known in the patent DE 102005003222 provided with a plurality of valve assemblies, each of which comprises a supply duct to convey the liquid of a tank to a container below; a tubular shutter mounted coaxially in the supply duct mobile between an open position and a closed position; a compensation cannula to define the level of liquid in the container and actuator means, which act, through two rings magnetically coupled with one another, on the compensation cannula moving it cyclically between the lifted position and a lowered position. The setting of a common height for the lowered position of the cannulae of all of the valve assemblies is carried out by adjusting the position of a lock ring, which stops the lowering stroke of the compensation cannula at a common height in their lowered position. In accordance with the solution described in this patent, the cyclical stroke that is carried out by the compensation cannulae is disadvantageously related to the common height decided upon for the lowered position of the cannulae. The aforementioned valve assembly also has the constructive complication of foreseeing that the compensation cannula of each one is arranged in a further duct arranged inside the shutter without the use of sealing gaskets between the cannula and the shutter.
A rotary filling machine is known in patent US 6,109,483 provided with a plurality of valve assemblies each of which comprises a supply duct to convey the liquid of a tank to a container below; a tubular shutter mounted coaxially in the supply duct mobile between an open position and a closed position; a compensation cannula for defining the level of liquid in the container and an actuator cylinder suitable for cyclically moving the compensation cannula between two end positions.
The adjustment of the end positions of the stroke of the cannula and therefore of the level of the liquid in the container is obtained by acting upon an adjustment screw mounted screwed inside the jacket of the actuator cylinder. Therefore, such a machine has the drawback of foreseeing an adjustment for each valve assembly. In this situation, the problem forming the basis of the present invention is that of avoiding the drawbacks shown in the prior art currently available, by providing a valve assembly for an isobaric machine for filling containers with liquids, which leads, within certain limits, to an improved duration of the sealing gaskets placed between the compensation cannula and the closing shutter of the duct for supplying liquid from the tank to the container.
A further purpose of the present finding is that of providing a valve assembly, which makes it possible to carry out a very wide adjustment of the level of liquid inside the container.
A further purpose of the present finding is that of providing a valve assembly, which makes it possible to command the closure of the valve for intercepting the liquid from the tank to the container irrespective of the lowering of the compensation cannula.
A further purpose of the present finding is that of providing a valve assembly, which is constructively simple and operatively completely reliable.
These purposes and yet more, are all achieved by a valve assembly for an isobaric machine for filling containers with liquids according to claim 1.
The technical characteristics of the finding, according to the aforementioned purposes, are clearly shown in the content of the claims below and its advantages shall become clearer from the following detailed description, with reference to the attached drawings, which represent an embodiment given purely as an example and not for limiting purposes, in which:

figure 1 shows a schematic plan view of an isobaric filling machine on which valve assemblies object of the present invention are mounted;
figure 2 shows a perspective view of the isobaric filling machine of figure 1;
figure 3 shows a side view of a valve assembly of the isobaric filling machine of figure 1;
figure 4 shows a section view carried out along the line III-III of figure 3.

In accordance with the figures of the attached drawings, a valve assembly object of the present invention has been wholly indicated with reference numeral 1, said valve assembly being intended to be mounted, together with a plurality of other completely analogous valve assemblies, on a rotary turntable or turret 2 of an isobaric filling machine 3 for filling containers 4 with a gassed liquid.
The isobaric filling machine can be inserted inside a bottling plant, which usually comprises, in a completely per se conventional manner, a rinsing machine and at least one capping machine mounted upstream and downstream of the isobaric filling machine 3, respectively, to which this is operatively connected through Archimedean screws 49, starwheels with recesses 50 or conveyor belts for transporting the containers 4.
Each valve assembly 1 is equipped with a support structure 5 intended to be peripherally fixed forming a seal below a tank 6 of the isobaric filling machine 3. On such a support structure 5 a poppet valve 7 and two degassing valves 8, 9 are mounted (or else only one degassing valve) which shall be described in more detail hereafter.
Inside the support structure 5, a supply duct of the liquid 11 is formed with a sleeve 10, said supply duct hydraulically putting the tank 6 in communication with the container 4 below, to convey the liquid contained in the tank 6 inside it, at a pressure which is greater than that of the atmosphere, with the purpose of keeping the gas dissolved inside it.
The supply duct 11 ends at the bottom after a shrunk portion 12 of the sleeve 10 with a spout 13, in which peripherally, around the tubular duct 11, holes for connecting to the poppet valve 7 and to the degassing valves 8, 9 are formed. On the lower face of the spout 13 a centring cone 14 is intended to form a seal, inside which the mouth of the container 4 grips on lifted by support plates (not shown) to lift towards the valve assembly 1.
The supply duct 11 continues through a hole 15 formed on the bottom 16 of the tank 6, up to vertically pushing inside it, through a guide sleeve 17 fixed at the bottom 16 itself and provided with wide side openings for the flow of liquid from the tank 6 to inside it. Preferably, in the guide sleeve 17, advantageously just above the tight portion 12, a mechanical filter is positioned so as to avoid possible foreign objects being introduced inside the valves.
Inside the supply duct 11, a tubular shutter 18 is concentrically mounted above the tight portion 12, said shutter being subjected to the pressure difference between the tank 6 and the container 4. Such a tubular shutter 18 is able to form a seal at the surface of the tight portion 12 of the supply duct 11, through a widened portion 19 thereof, with a tapered shape, peripherally provided with a resting gasket 20, able to sealingly rest on the inner surface of the sleeve 10 closing the supply duct 11. Functionally, the tubular shutter 18 is moved, as specified hereafter, between an open position, in which it has its widened portion 19 arranged lifted by the supply duct 11 to allow the passage of liquid towards the container 4, and a closed position, in which it forms a seal with its widened portion 19 on the supply duct 11 blocking the passage of liquid towards the container 4.
A first spring 21 is coaxially mounted around the tubular shutter 18 and is placed between a first abutment disc 22, circumferentially fixed projecting out from said tubular shutter 18, and a first shoulder 23, arranged annularly on the guide sleeve 17. Such a first spring 21 is biased to vertically act upon the tubular shutter 18 in the direction to push it towards the open position i.e. with its widened portion 19 away from the surface of the tight portion 12 of the supply duct 11.
When the container 4 against the centring cone 14 has not yet been brought to the pressure of the tank 6 (isobaric filling condition), the pressure difference to which the tubular shutter 18 is subj ected overcomes the force of the first spring 21 keeping the tubular shutter 18 in the closed position on the supply duct 11.
As soon as the pressure in the container 4 is brought to the pressure of the tank 6, the pressure forces on the tubular shutter 18 compensate each other and the latter, subj ected only to the elastic return force of the first spring 21, instantaneously opens allowing the liquid to pass in the supply duct 11 and thus in the tank 6.
More in detail, each valve assembly 1 of the isobaric filling machine 3 comprises, in a manner which is per se known by a man skilled in the art and for this reason shall not be illustrated in detail, a valve for intercepting a vacuum circuit 24 intended to suck all the air from the container 4 as soon as this is brought by the support plate with the centring cone 14 sealed on the spout 13 of the supply duct 11. Advantageously, to make the different operations of the filling cycle faster, the poppet valve 7, arranged near to the container 4, is always subjected to the action of the different operation fluids early so as to avoid having to wait the time necessary to bring a long portion of duct of the selected operative circuit up to pressure, before obtaining the desired result in the container 4.
Once the air has been sucked out from the container 4, it is put in communication with a valve of the isobaric circuit 25, i.e. with the valve intended to bring the container to the pressure of the tank 6 making the air of the tank 6 itself, i.e. an inert gas, flow therein.
At this stage, as explained previously, the tubular shutter 18 moves into the open position, and the liquid flows from the tank 6 to the container 4 with there being a compensation cannula 26 for the return of air from the container 4 to the tank 6. More in detail, each valve assembly 1 is indeed provided with a compensation cannula 26, which is mounted coaxially to seal with at least two gaskets 27 and 28 inside the tubular shutter 18.
During the filling step of the container 4, the compensation cannula 26 makes it possible to evacuate the air contained inside it so as to prevent a back-pressure from forming opposing the lowering of the liquid, as well as to evacuate the liquid in excess during the subsequent step of defining the level of liquid in the container 4. Functionally, the aforementioned compensation cannula 26 is able to be moved cyclically sliding inside the tubular shutter 18 between a raised position, in which it makes it possible to correctly carry out the degassing step, and a lowered position in which it is inserted for at least a lower portion inside the container 4 with the open bottom end 29 placed at a predetermined height for defining the level of liquid inside it.
The compensation cannula 26 is interrupted by a valve 360 which subdivides it into a lower portion 26' for the passage of fluids, and an upper portion 26" for commanding the movement of the compensation cannula 26 itself.
The lower portion 26' ends at the top with a mouth 270 which is in communication with the inside of the tank 6. The compensation cannula 26 continues upwards beyond the valve 360 with the upper portion 26" made up by a hollow vertical shaft inside which a control rod 41 is slidingly inserted. The latter, as shall be described hereafter, is subject to opening and closing the mouth of the compensation cannula 26.
More in detail, on the lower portion 26' of the compensation cannula 26 at its mouth 270 a cup 260 (for example by welding) is fixedly mounted which acts as an abutment for a second spring 261 which acts upon a mobile shutter 262 having the shape of a cup tipped upside down, so as to keep it normally lifted on the mouth 270 of the compensation cannula 26. The cup 260 is then fixed, for example through bayonet coupling 264, at the lower end of the upper portion 26" (hollow command shaft) of the compensation cannula 26. The lifting and lowering movement of the upper portion 26" of the cannula 26 defines the consequent lowering and lifting of the lower portion 26' as well without modifying the position of the shutter 262. According to the idea forming the basis of the present invention, means are foreseen for adjusting the level of liquid to carry out the levelling of the liquid in the containers 4 at a height which can be suitably adjusted.
Such adjustment means comprise, for this purpose, first actuator means 30, which are fixedly attached to a support base 31 and act upon the compensation cannula 26, and more precisely on the upper portion 26" of the compensation cannula 26 made up of a hollow command shaft, moving it at each filling cycle of a container 4, between the aforementioned lifted position, to make it possible to correctly carry out the degassing, and the lowered position, to define the level of predetermined liquid in the container 4.
More in detail, when the compensation cannula 26 is in the lowered position with the open bottom end 29 which has reached the predetermined height, a levelling of the liquid occurs at such a height (compensation step) through blowing of inert gas inside the container 4 through a valve of an automatic levelling circuit 42, and there is the consequent passage of liquid through the compensation cannula 26 up until it returns inside the tank 6.
The compensation cannula 26 is normally in a lifted position and is moved downwards, in the lowered position, for the aforementioned compensation step, aimed at defining the predetermined level of liquid in the bottle.
During the degassing, on the other hand, it is important for the compensation cannula 26 to be lifted, for example preferably by 15 mm, above the surface of the liquid. Indeed, if the compensation cannula 26 touches the surface of the liquid, pressurised gas would remain inside it causing strong perturbations of the liquid, during the degassing step, with pressure peaks which is indeed important to avoid. Of course, in the case of liquids without gas, the compensation cannula 26 could remain in the lowered position so as to avoid pointless wearing of the gaskets with the cyclical rising and lowering of the compensation cannula 26 itself.
In order to vary the predetermined level, the adjustment means further comprise second actuator means 32, which act upon the support base 31 moving it vertically in a controlled manner between different heights corresponding to different levels of the open bottom end 29 of the compensation cannula 26.
In accordance with a special characteristic of the present invention, the tubular shutter 18 is moved in a separate manner between the lifted and lowered position by third actuator means 33.
In accordance with the present invention, the closing and the opening of the supply duct 11 through the tubular shutter 18 does not, like for the valve assemblies of the type known before now, mechanically depend on the movement of the compensation cannula 26, thus making it possible to freely subdivide the movement of the compensation cannula 26 in the two different strokes, of which one cyclic stroke to be carried out each time a container 4 is filled , for example in the order of 10 mm, to bring the open lower end 29 always at the same predetermined level, and an adjustment stroke to set the level at the start of the operation of the filling machine 3 i.e. each time the format of the container 4 is changed. The adjustment stroke can be extended, in accordance with the valve assembly object of the present invention, without the limitations of the valve assemblies known to this day, also up to 80 mm. In accordance with the preferred embodiment illustrated in the attached figures, the third actuator means 33 consist of a first pneumatic cylinder 33', which is coaxially passed through by the upper portion 26" of the compensation cannula as well as by the control rod 41 for closing the valve 360. Such a first cylinder 33' is equipped with a first sealing disc 34 which, at the bottom, pushes an elongated frame 35 arranged around the compensation cannula 26 and formed by some vertical shafts i.e. by a partially opened tube.
The elongated frame 35 extends at the bottom to the first abutment disc 22 fixedly connected to the tubular shutter 18. Therefore, the first pneumatic cylinder 33', according to predetermined operative steps commanded by a logic control unit, causes the rising and the lowering of the tubular shutter 18.
More precisely, the upward opening movement of the tubular shutter 18 is ensured by the first spring 21 when the pneumatic supply is cut off from the first pneumatic cylinder 33' and the pressures on the tubular shutter 18 are compensated.
In turn, the first actuator means 30 consist of a second single acting pneumatic cylinder 30' with a return spring 400, which is equipped with a second sealing disc 70 fixed centrally to the upper portion 26" of the compensation cannula 26.
In accordance with a different embodiment not illustrated in the attached figures the upward movement of the compensation cannula 26, once the automatic levelling step of the liquid in the container 4 is finished, is ensured by a third spring when the pneumatic supply is cut off from the second pneumatic cylinder 30'.
Such a third spring is mounted coaxially, externally with respect to the first 21, and is placed between a second abutment disc, circumferentially fixed projecting from said compensation cannula 26, and a second shoulder, arranged annularly on the guide sleeve 17.
Openings are formed in the abutment disc for the free passage of the elongated frame 35.
Such a third spring is biased to vertically act upon the compensation cannula 26 in the direction to push it towards the retracted position with its lower end 29 preferably outside the container 4 so as to avoid that during the filling operation it can be damaged by the explosion of a container and avoid that during the degassing operations it produces perturbations on the free surface of the liquid.
The aforementioned second actuator means 32 move the support base 31 on which the second pneumatic cylinder 30', that moves the compensation cannula 26 through transmission means, is mounted.
These means are equipped with an adjustment ring 36 fixed at the support base 31 of all of the valve assemblies 1, and moved for example by one or more linear actuators with a trapezoidal screw. More in detail such a linear actuator is provided with a trapezoidal screw 37 that engages in the internally threaded through-cavity of a gear wheel 38 driven into rotation by a motor 39.
Each valve assembly also comprises fourth actuator means 40 which are mounted on the top end of the upper portion 26" of the compensation cannula 26 and are suitable for opening and closing the mouth according to predetermined operative steps.
Such actuator means consist of a fourth pneumatic cylinder 40' that moves a control rod 41, which is subj ect to sliding in the hollow shaft of the upper portion 26" of the compensation cannula 26 with which it seals through a fourth gasket 263. When the control rod 41 lowers it acts with its lower end upon the cup-shaped shutter 262 of the valve 360 to push it closed against the mouth 270 of the compensation cannula 26. The opening return of the mouth is ensured by the second spring 261.
The closure of the valve 360 by the control rod 41 occurs when there is not a container, during the degassing and during the pressurising step to avoid taking away pressure from the tank 6.
Functionally, carrying on what has previously been described, once the filling step of the container 4 has finished, the logic control unit commands the supply duct 11 to close by means of the tubular shutter 18 which is lowered through the first pneumatic cylinder 33' and the lowering of the compensation cannula 26 through the second pneumatic cylinder 30' until it is brought with the lower open end 29 at the predetermined height for defining the level of liquid inside the container 4. Suitably, the aforementioned predetermined height for defining the level of liquid shall have been adjusted at the desired height, in a previous step of setting of the machine, moving the support base 31 on which the second pneumatic cylinder 30' is mounted, said cylinder moving the compensation cannula 26 through the controlled actuation of the motor 39 for an adjustment stroke which can also be of 80 mm. At this stage, in a per se conventional way, the valve of an automatic levelling circuit 42 is opened which, through the poppet valve 7, commands the flow of inert gas inside the container 4 making the liquid contained in it rise back up through the compensation cannula 26 until the predetermined height has been reached.
Once the levelling step of the liquid in the container 4 is over, the logic control unit, through the fourth cylinder 40', commands the closure of the upper mouth of the compensation cannula 26 with the shutter lid 41, and through the second pneumatic cylinder 30' commands the rising of the compensation cannula 26 into the lifted position. Consequently, the control unit commands the opening in sequence of the two degassing valves 8, 9, suitable for bringing the pressure of the container 4 to an intermediate pressure first and then to ambient pressure (or else directly to ambient pressure without passing by an intermediate pressure).
Thanks to the valve assembly 1 object of the present invention the closure of the supply duct 11 through the tubular shutter 18 and the movement of the compensation cannula 26 are commanded in a separate manner leading to a limited sliding between the two mechanical parts during the normal repetitive operation cycle of the valve assembly 1. On one hand this makes it possible to avoid excessive wearing of the sealing gaskets 27, 28 placed between the compensation cannula 26 and the tubular shutter 18 and on the other hand it makes it possible to substantially increase the adjustment stroke for defining the level of the liquid in the containers 4. Advantageously, through the second actuator means 32 it is possible, during the sanitization step, to lift the compensation cannula 26 in a lifted rinsing position so as to make it possible to wash the outside of the compensation cannula 26.
More in detail, the compensation cannula 26 has in its lower portion 26' two tight portions 150, 151, which, when the cannula 26, during the sanitization step, is lifted into the foreseen rinsing position, are arranged at the two sealing gaskets 27, 28 allowing the fluid to pass between the cannula 26 itself and the tubular shutter so as to carry out a complete cleaning of the outer surface of the cannula 26. In accordance with the embodiment illustrated in the attached figures, the lower portion 26' of the compensation cannula 26 has a widened step-like reinforcement portion for about one third of its extension from the open lower end 29. When the cannula 26 is in the aforementioned lifted rinsing position (for example corresponding to an extra stroke of 5mm beyond the maximum adjustment stroke of 70-80 mm of the second actuator means 32) the gasket, indicated with reference numeral 290 mounted on the guide sleeve 17 and arranged, during the normal filling cycle of the machine, at the upper portion having greater diameter of the cannula 26, is at the lower portion having shorter diameter of the cannula 26, allowing the liquid to pass and the entire cannula 26 to be sanitised.
The finding thus conceived achieves the aforementioned purposes.
Of course, it can in its practical embodiment, take up also shapes and configurations which are different from those illustrated above without for this reason departing from the present scope of protection as defined in the appended claims.
Moreover, all the details can be replaced by technically equivalent elements and the dimensions, the shapes and the materials used can be any according to the necessity.

Claims

Valve assembly (1) for an isobaric machine for filling containers with liquids, which comprises:
- a support structure (5) intended to be fixed peripherally below a tank (6) of said isobaric filling machine (3);

- a supply duct (11) arranged on said support structure (5) in communication with said tank (6) to convey the liquid contained in it to a container below (4);

- a tubular shutter (18) mounted coaxially in said supply duct (11) suitable for being subjected to the pressure difference between said tank (6) and said container (4), able to be moved between at least one open position, in which it is lifted from said supply duct (11) allowing the liquid to pass towards said container (4), and a closed position, in which it is in contact with said supply duct (11) blocking the passage of the liquid;

- a compensation cannula (26) mounted coaxially in a sealed manner in said tubular shutter (18), suitable for receiving a fluid coming out from said container (4), able to be moved cyclically between a raised position, and a lowered position in which it is inserted with the open bottom end (29) in said container (4) at a predetermined height for defining the level of liquid inside it;
it further comprises means for adjusting the level of liquid inside said container (4) comprising:
- first actuator means (30) fixedly connected to a support base (31), which act upon said compensation cannula (26) moving it cyclically between said raised position and said lowered position, in which, at the predetermined height reached by said open bottom end (29) of said compensation cannula (26), it carries out a levelling of the liquid through blowing of gas in said container (4) with consequent passage of liquid in said compensation cannula (26);

- second actuator means (32) acting upon said support base (31) to move it vertically in a controlled manner between different heights corresponding to different predetermined heights for defining the level of the open bottom end (29) of said compensation cannula (26);

- third actuator means (33) acting upon said tubular shutter (18) to move it selectively between said open position and said closed position.
Valve assembly (1) according to claim 1, characterised in that said third actuator means (33) are fixed above said tank (6) and act upon said tubular shutter (18) through an elongated frame (35) arranged around said compensation cannula (26) and at the bottom carrying a mounted first abutment disc (22) fixed to the upper end of said tubular shutter (18).
Valve assembly (1) according to claim 1, characterised in that it comprises a first spring (21) acting upon said tubular shutter (18) to push it towards said open position with a reaction force suitable for being overcome by said pressure difference when said container (4) is absent.
Valve assembly (1) according to claim 2, characterised in that said third actuator means (33) comprise a first pneumatic cylinder (33'), which is passed through coaxially by said compensation cannula (26) free to slide through it, and is equipped with a first sealing disc (34) fixed to said elongated frame (35) to move said tubular shutter (18) through it.
Valve assembly (1) according to claim 1, characterised in that said first actuator means (30) consist of a second pneumatic cylinder (30'), which is equipped with a second sealing disc (70) fixed centrally to said compensation cannula (26) which passes through said second pneumatic cylinder (30') coaxially.
Valve assembly (1) according to claim 1, characterised in that it comprises fourth actuator means (40) mounted on the top end of said compensation cannula (26) suitable for opening it and closing it according to predetermined operative steps through a control rod (41).
Valve assembly (1) according to claim 1, characterised in that said second actuator means (32) comprise transmission means acting upon the support base (31) of the first actuator means (30) of all of the valve assemblies (1).
Valve assembly (1) according to claim 7, characterised in that said transmission means are equipped with an adjustment ring (36) fixed to said support base (31) and equipped with a trapezoidal screw (37) that engages in the internally threaded through-cavity of a gear wheel (38) driven into rotation by a motor (39).
Valve assembly (1) according to claims 2 and 3, characterised in that said first spring (21) is interposed between said first abutment disc (22) and a guide sleeve (17) fixed onto the bottom of said tank (6) concentrically to said tubular shutter (18).