MACHINE FOR FILLING CONTAINERS WITH LIQUIDS, PROVIDED WITH A FILLING LEVEL CORRECTION SYSTEM

Abstract

The present invention relates to a machine 1 for filling containers with liquids, comprising: a support structure; a rotating carousel provided with a tank; a plurality of valve groups mounted on said carousel for filling containers; and a logic control unit suitable to automatically manage the operation of the filling machine. Each valve group comprises an air return tube which is provided with an open lower end, susceptible to be inserted in a container, and an opposite upper end and can be moved axially between at least one lowered position and a raised position. Each valve group comprises: means for guiding the axial movement of the return air tube between a lower end stop and an upper end stop, wherein said at least one lowered position is between said two end stops; elastic mechanical means suitable to exercise constantly an axial thrust action on the return air tube towards the raised position; means for reversibly blocking the return air tube in any axial position between said lower end stop and said upper end stop; and a cam follower rigidly connected to the tube. The filling machine comprises a cam which is placed peripherally to the rotating carousel at a first angular position 1 with respect to an entry station to be cyclically engaged by the cam follower. The cam is profiled so as to impose on each tube a predetermined axial displacement H towards the lower end stop and has a circumferentially limited operating angle of working . The filling machine 1 comprises means for moving the cam in height. The logic control unit is operatively connected to the means for moving the cam in height and to the reversible blocking means of each return air tube and is programmed: to command the blocking of the blocking means when the individual tube is located within the operating angle of working of the cam to keep the return air tube in the lowered position, and to command the unblocking of the reversible blocking means of each individual air return tube at a second angular position chosen as a function of the filling operating cycle to be performed on the containers.

Claims

1. Machine for filling containers with liquids, provided with a filling level correction system, which comprises: a support structure; a rotating carousel rotatably mounted on said support structure, and provided with a tank for containing a liquid to be bottled in containers; a plurality of valve groups mounted peripherally on said rotating carousel each responsible for filling a container; and a logic control unit suitable to automatically manage the operation of said filling machine, wherein each valve group comprises: a supply duct hydraulically connected to said tank for the inflow of said liquid from said tank into said containers to be filled; a shutter placed to intercept said supply duct to adjust the inflow of said liquid into said containers; a return air tube which is mounted coaxially inside said supply duct and is provided with an open lower end, susceptible to be inserted in said container, and a upper end, which is opposite said lower end and can be connected hydraulically to said tank or to a separate drainage circuit, said return air tube being movable axially between at least one lowered position and a raised position, regardless of said shutter; and a duct which can be fluidically connected to a pressurised gas circuit to introduce gas into the container at the end of filling and thus expel through said tube the excess liquid that may have filled the container beyond the height at which the lower end of the return air tube is placed, corresponding to said lowered position, thereby performing a correction of the filling level, wherein each valve group comprises: means for guiding the axial movement of the return air tube between a lower end stop and an upper end stop, wherein said at least one lowered position is between said two end stops; elastic mechanical means suitable to exercise constantly an axial thrust action on said return air tube towards said raised position; means for reversibly blocking the return air tube in any axial position between said lower end stop and said upper end stop; and a cam follower rigidly connected to said return air tube; and wherein said filling machine comprises a cam which is placed peripherally to said rotating carousel at a first angular position 1 with respect, to an entry station to be cyclically engaged by the cam follower of each valve group, wherein said cam is profiled so as to impose on each tube by means of the relative cam follower a predetermined axial displacement H from a position corresponding to the upper end stop towards said lower end stop, overcoming the opposite thrust of said elastic mechanical means and placing the tube in a lowered position with respect to the position corresponding to the upper end stop, said cam having an operating angle of working which covers only a portion of the circumferential extension of the rotating carousel, and wherein said filling machine comprises means for moving the cam in height in relation to said support structure in order to adjust the height corresponding to said lowered portion, and wherein the logic control unit is operatively connected to the means for moving the cam in height to adjust automatically the height corresponding to said lowered position, as well as to the reversible blocking means of each return air tube so as to command the blocking and unblocking action, wherein said logic control unit is programmed: to command the blocking of the reversible blocking means of each individual return air tube when the individual tube is located within the operating angle of working of the cam to keep the return air tube in the lowered position which it was brought to by said cam itself, opposing the action of the elastic mechanical means, and to command the unblocking of the reversible blocking means of each individual air return tube at a second angular position 2 chosen as a function of the filling operating cycle to be performed on the containers, so as to allow the return of the individual tube to the raised position under the action of the relative elastic mechanical means, said second angular position 2 being placed downstream of the first angular position 1 and upstream of an exit station 6.

2. Filling machine according to claim 1, wherein the cam is attached directly to said support structure or is associated to support elements separate from the support structure of the rotating carousel.

3. Filling machine according to claim 1, wherein the means for moving the cam in height in relation to said support structure comprise one or more electric motors.

4. Filling machine according to claim 1, wherein the first angular position 1 of the cam is fixed.

5. Filling machine according to claim 1, comprising means for angularly moving the cam around the axis of rotation of the carousel in order to vary the first angular position 1 with respect, to the entry station of the containers in the filling machine.

6. Filling machine according to claim 5 wherein the logic control unit is operatively connected to the angular movement means or the cam to automatically adjust the first angular position 1 of the cam with respect to the entry station of the containers in the filling machine.

7. Filling machine according to claim 1, wherein the means for guiding the axial movement of the return air tube comprise: one or more linear guides, which are constrained to the rotating carousel and extend themselves between two end supports which define the two end stops; and a carriage, which is slidingly associated to said guides and bears the cam follower, the tube being rigidly constrained to said carriage to move integrally therewith.

8. Filling machine according to claim 7, wherein said one or more linear guides are constrained to the rotating carousel on the top of the tank to extend themselves in height outside said tank, and wherein the tube is rigidly constrained to the carriage at a portion thereof which stays outside the tank.

9. Filling machine according to claim 7, wherein the elastic mechanical means of each individual tube are operatively associated to the axial guide means and are suitable to indirectly exert their thrust on the tube acting on the carriage.

10. Filling machine according to claim 9, wherein the carriage is provided with a rod rigidly fixed to it to extend itself in height parallel to said one or more guides, and wherein the elastic mechanical means consist of a mechanical coil spring which is mounted coaxially to said rod to act in thrust between said rod and a support of said one or more guides.

11. Filling machine according to claim 10, wherein said rod is axially inserted inside a protective sheath, preferably said sheath comprising at least one axially deformable portion associated with said rod.

12. Filling machine according to claim 10, wherein the reversible blocking means of the return air tube act on said rod to reversibly block the axial movement with respect to said one or more guides.

13. Filling machine according to claim 1, wherein the reversible blocking means consist of an electro-pneumatically actuated friction blocking device.

14. Filling machine according to claim 12, wherein the reversible blocking means consist or an electro-pneumatically actuated friction blocking device and wherein said electro-pneumatically actuated friction blocking device comprises an elastically deformable sleeve mounted coaxially on said rod inside a closed chamber connected to a pressurised gas circuit, wherein said sleeve is susceptible to shift upon a variation of the internal pressure of said chamber between a position of adherence to the rod, in which the sleeve prevents the axial sliding of the rod exerting thereon sufficient friction to overcome the action of the elastic mechanical means and a position of non-adherence, wherein the sleeve permits the axial sliding of the rod not exerting thereon sufficient friction to overcome the action of the elastic mechanical means, the passage between said two positions being controlled pneumatically by means of a solenoid valve which is suitable to control the inflow of pressurised gas inside said chamber and is operatively connected to the logic control unit.

15. Filling machine according to claim 1, wherein each valve group comprises a level sensor, preferably associated with the return air tube.

16. Filling machine according to claim 1, characterised in that it is an isobaric filling machine wherein the logic control unit is programmed in such a way that depending on the format of container handled by the filling machine the second angular position 2 is chosen ensuring that the return of the tube to the raised position occurs before a decompression phase of the container.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The technical features of the invention, according to the aforesaid objects, can clearly be seen in the content of the claims below, and its advantages will become more readily apparent in the detailed description that follows, made with reference to the accompanying drawings, which illustrate a preferred embodiment, which is purely exemplary and not limiting, in which:

[0037] FIG. 1 shows a schematic plan view of the filling machine object of the present invention;

[0038] FIGS. 2 and 3 show two different perspective views of the filling machine illustrated in FIG. 1;

[0039] FIG. 4 shows an enlarged view of a detail in FIG. 3 (with some parts removed to better highlight others) regarding a cam for positioning the return air tubes of the filling valves;

[0040] FIG. 5 shows a sectional view of a detail of the filling machine in FIG. 1, taken along to the section plane V-V indicated in FIG. 1;

[0041] FIG. 6 shows a sectional view of a detail of the filling machine in FIG. 1 (with some parts removed to better highlight others), said section being taken along the section plane VI-VI indicated in FIG. 1;

[0042] FIG. 7 shows a perspective view of a detail of the filling machine in FIG. 2 with some parts removed to better highlight others, regarding a single filling valve, illustrated with the return air tube in a raised position;

[0043] FIG. 8 shows an orthogonal sectional view of the filling valve shown in FIG. 7, according to a radial section plane passing through the return air tube of said valve;

[0044] FIG. 9 shows the valve in FIG. 7, illustrated with the return air tube in a lowered position;

[0045] FIG. 10 shows an orthogonal sectional view of the filling valve shown in FIG. 9, according to a radial section plane passing through the return air tube of said valve; and

[0046] FIG. 11 shows an orthogonal partially sectional view of a detail of the filling valve shown in FIG. 10 according to the arrow XI shown therein, regarding a guide, lifting and blocking system of the return air tube.

DETAILED DESCRIPTION

[0047] With reference to the accompanying drawings, reference numeral 1 indicates as a whole the machine for filling containers with liquids provided with a system for correcting the filling level object of the present invention.

[0048] It is intended for bottling containers 2 with drinking liquids, either carbonated or not carbonated.

[0049] The subject filling machine 1 is inserted, in a completely traditional manner, in a bottling plant or line provided with several machines that work in succession, and is positioned in particular downstream of a rinsing machine and upstream of a capping machine. The containers 2 are transferred from one machine to another by means of conveying lines, such as for example conveyor belts, or by means of transport equipment such as for example star wheels, screw conveyors, etc.

[0050] More in detail, with reference to the embodiment illustrated in FIG. 1, the filling machine 1 is conventionally provided with an entry station 3, in which it receives the containers 2 to be filled from a first conveyor line 4 (for example, a first star wheel 5), and an exit station 6, in which the filled containers 2 are released to a second conveying line 7 (by means of, for example, a second star wheel 8) to be conveyed towards a downstream machine, such as example a capping machine.

[0051] The filling machine 1 is provided with a support structure 9, on which a rotating carousel 10 is rotatably mounted, brought in rotation around an axis of rotation X by means of known motor means (not shown).

[0052] The rotating carousel 10 is provided with a tank 12, preferably of an annular shape, inside which the liquid to be bottled is contained. In particular, the tank 12 is filled with the liquid to be bottled up to a certain level, above which an inert gas (such as nitrogen) is introduced. This inert gas is kept substantially at atmospheric pressure when the filling machine 1 is of the gravity type, under light vacuum when the filling machine 1 is of the type under slight depression and under pressure when the filling machine 1 is of the isobaric type for the treatment of carbonated liquids.

[0053] The rotating carousel 10 carries peripherally mounted a plurality of valve groups 13, uniformly distributed along its circumference, and adapted to transfer the liquid from the tank 12 to the underlying containers 2 to be filled, generally consisting of glass or plastic bottles.

[0054] In particular, the rotating carousel 10 comprises a support base (not shown in the figures) which is rotatably associated with the fixed support structure 9, preferably by means of a fifth wheel (not shown). In turn, the base supports the tank 12 by means of a plurality of columns which have the function of varying the distance between the base and the tank according to the height of the containers 2 to be filled.

[0055] The support base furthermore has peripherally support means 17 for supporting the containers with respect to the valve groups 13 associated with the tank. These support means 17 can be actuated to move between a first position, in which they bring the mouth 2 of the container 2 in sealing relation with an supply duct 14 of the corresponding valve group 13, and a second position, in which they receive the container 2 when they pass through the entry station 3 of the filling machine 1. In particular, the support means 17 of the containers 2 comprise a plurality of support plates 18, mounted peripherally on the rotating carousel 10 below the corresponding valve groups 13 and intended to receive the containers 2 in support during their operating run on the rotating carousel 10.

[0056] Preferably, during the rotation of the rotating carousel 10, each support plate 18 is driven to move between the aforementioned first position and the aforementioned second position by means of a fixed cam (not shown), arranged around the rotating carousel 10, and acting with a shaped profile thereof on a cam follower 19 (consisting for example of an idle wheel) fixed to the corresponding support plate 16. The support means 17 are of the traditional type and, being well known to a man skilled in the art, will not be described in more detail.

[0057] The subject filling machine 1 comprises a logic control unit 200 (preferably comprising a PLC) suitable for automatically managing the operation of the filling machine.

[0058] The rotating carousel 10 comprises a plurality of manifolds and circuits with process fluids. These manifolds and circuits are functional for carrying out the various operating steps envisaged by the filling cycle of the filling machine 1. For this purpose, each valve group 13 is fluidically connected to the aforementioned plurality of circuits and manifolds by means of suitable control valves indicated as a whole with V in the accompanying figures.

[0059] The control valves V of each valve group 13 are preferably of the pneumatic type, and are actuated by the injection of pressurized gas from a source of pressurized gas (not shown) controlled by the logic control unit 200 of the filling machine 1.

[0060] Preferably, when the filling machine 1 is intended for filling with carbonated liquids (i.e. it is of isobaric type), the operating steps of the filling cycle are as follows:

[0061] step 1): entry of container 2 into the filling machine;

[0062] step 2): sealably matching the container 2 to a filling valve group 13;

[0063] step 3): vacuum and inertization of the container 2;

[0064] step 4): pressurization of the container 2;

[0065] step 5): Filling of the container 2;

[0066] step 6): Correction of filling level in the container 2;

[0067] step 7): Decompression (or degassing) of the container 2; and

[0068] step 8): separation of the container from the valve group;

[0069] step 9): exit of the container from the filling machine.

[0070] Generally, when the filling machine 1 is of the gravity type or under light vacuum, steps 4) and 7) are not provided.

[0071] The operating steps listed above are all well known to a man skilled in the art and will therefore not be described in greater detail.

[0072] Preferably, depending on the filling cycle which the filling machine must perform, the rotating carousel 10 of the filling machine 1 may therefore comprise all or part of the following circuits or manifolds:

[0073] a vacuum circuit (for the vacuum step 3);

[0074] a circuit with inert gas (for the inertization step 3);

[0075] a first circuit with pressurized gas (for the pressurization step 4);

[0076] a second circuit with pressurized gas (for the level correction step 6);

[0077] at least one manifold for pressure relief in the container (for the depressurization step 7).

[0078] a drainage manifold of the air exiting the container during filling, as an alternative to the tank;

[0079] a collector for collecting the liquid expelled from the container during the level correction step 6), as an alternative to the tank.

[0080] More in detail, each valve group 13 responsible for filling the containers 2 comprises:

[0081] a supply duct 14 hydraulically connected to the tank 12 for the inflow of the liquid from the tank 12 into the underlying containers 2 to be filled; and

[0082] a shutter 15 placed to intercept the supply duct 14 to adjust, the inflow of the liquid into the containers 2.

[0083] Preferably, the shutter 15 of each valve group 13 is driven by a double-acting pneumatic cylinder controlled by the logic control unit 200.

[0084] Each valve group 13 further comprises a return air tube 16 mounted coaxially within the supply duct 14. The return air tube 16 is provided with an open lower end 16 susceptible of being inserted into the container 2 for hydraulically adjusting the maximum level of the liquid in the container 2 itself during the filling of the latter, and with an upper end 16 opposite the lower end 16, and preferably positioned above a lid 12 of the tank 12. The upper end 16 of the return air tube may be hydraulically connected to the tank 12 or to a separate drainage circuit. The return air tube 16 may be moved axially between at least one lowered position and one raised position, independently of the shutter 15.

[0085] Operationally, a container 2 associated with a valve group 13 in its operating run on the rotating carousel 10 will be subjected in sequence to the various operating steps. Each operating step develops itself in a specific angular sector between the entry station 3 and the exit station 6.

[0086] More in detail, the return air tube 16 of each valve group 13 is moved in lifting and lowering as a function of the operating step being performed by the corresponding valve group 13.

[0087] During the filling step 5), the return air tube 16 allows the air in the container 2 to escape. During this step, the tube 16 can be fluidically connected to the tank 12 to discharge the air coming from the container therein or with a separate drainage circuit to prevent the air coming from the container from contaminating the tank.

[0088] During the level correction step 6), the return air tube 16 allows the expulsion of the excess liquid which may have filled the container beyond the positioning portion of the lower end of the return air tube. During this step, the tube 16 may be fluidically connected to the tank 12 to discharge the liquid expelled from the container therein, or to a separate drainage circuit to prevent the liquid expelled from the container from contaminating the tank.

[0089] Preferably, the return air tube 16 is maintained in the raised position from the entry step 1) of the container into the filling machine 1 up to and including the pressurization step 4). This is functional to increase the working angle of the filling machine, to reduce the risk of collisions of the tube against the container and to protect the tube from possible bursts of the container itself. The tube 16 is then brought to a lowered position (established as a function of the filling level to be obtained in the container) during the filling step 5), preferably before the end of this step 5) and is maintained in this position for the whole step 6) of correction of the filling level.

[0090] If a decompression step 7) is provided, the tube 16 is returned to the raised position before carrying out such a step 7), in order to carry out the decompression of the container with the lower end 16 of the tube 16 not in contact with the liquid. If, however, a decompression step 7) is not provided, the tube 16 is in any case returned to the raised position before carrying out the step 6) of separating the container from the valve group.

[0091] According to a first essential aspect of the present invention, each valve group 13 comprises:

[0092] means 50 for guiding the axial movement of the return air tube 16 between a lower end stop and an upper end stop,

[0093] elastic mechanical means 60 suitable to exercise constantly an axial thrust action on the return air tube 16 towards said raised position;

[0094] means 70 for reversibly blocking the return air tube in any axial position between said lower end stop and said upper end stop; and

[0095] a cam follower 80 (for example consisting of an idle wheel) rigidly connected to the return air tube 16.

[0096] The aforesaid at least one lowered position of the return air tube (which fixes the filling level in the containers 2) is included between the two end stops defined by the axial guide means 50.

[0097] As will be resumed hereinafter, the reversible blocking means 70 of the return air tube consist of electro-actuated devices in order to allow the control thereof through the logic control unit 200.

[0098] According to another essential aspect of the present invention, the filling machine 1 comprises a cam 90 which is placed peripherally to the rotating carousel 10 at a first angular position 1 with respect to an entry station 3 of the containers into the filling machine to be cyclically engaged by the cam follower 80 of each valve group 13.

[0099] As shown in particular in FIGS. 4 and 6, the cam 80 is profiled so as to impose on each tube a predetermined axial displacement H through the respective cam follower 80 from a position corresponding to the upper end stop towards the aforesaid lower end stop, overcoming the opposite thrust of the aforesaid elastic mechanical means 60. In this way, the cam 90 positions the tube 16 in a lowered position with respect to the position corresponding to the upper end stop.

[0100] The cam 90 has an operating angle of working which covers only a portion of the circumferential extension of the rotating carousel 10.

[0101] According to the invention, the filling machine 1 comprises means 100 for moving the cam 90 in height with respect to the support structure 9. Those means 100 therefore allow adjusting the height corresponding to the aforementioned lowered position imposed by the cam 90 to each individual return air tube 16.

[0102] According to a further essential aspect of the present invention, the logic control unit 200 is operatively connected to:

[0103] the means 100 for moving the cam 90 in height to automatically adjust the height corresponding to the aforementioned lowered position, so as to allow an automatic format change; and

[0104] the reversible blocking means 70 of each return air tube so as to control the intervention thereof in blocking and unblocking.

[0105] According to the invention, the aforementioned logic control unit 200 is programmed to command the blocking of the reversible blocking means 70 of each individual return air tube 16 when the individual tube 16 is located within the operating angle of working of the cam 90 to keep the return air tube 16 in the lowered position which it was brought to by said cam itself, opposing the action of the elastic mechanical means 60 once the relative valve group 13 has exited the operating angle of working of the cam 90.

[0106] According to the invention, the aforementioned logic control unit 200 is further programmed to command the unblocking of the reversible blocking means 70 of each individual air return tube 16 at a second angular position 2 chosen as a function of the filling operating cycle to be performed on the containers, so as to allow the return of the individual tube 16 to the raised position under the action of the relative elastic mechanical means 60.

[0107] The aforementioned second angular position 2 is located downstream of the first angular position 1 and upstream of the exit station 6 of the containers from the filling machine with respect to the rotation direction of the carousel 10.

[0108] Advantageously, the logic control unit 200 is provided with a user interface (not shown), through which it is possible to input data relating to the features of the optimal operating cycles for each container format into a memory unit.

[0109] The invention is based on a combination of mechanical devices and electromechanical devices that allows combining the typical reliability of mechanical cam systems with the typical flexibility of electromechanical systems, without however requiring the use of pneumatic cylinders or electric motors (extremely flexible, but very expensive and less reliable than mechanical systems) for moving the return air tubes, an essential aspect for an automatic management of the format change and optimization of the filling cycle of the filling machine.

[0110] More in detail, as described above, the positioning of all the return air tubes 16 is in fact obtained by means of a single cam 90, which is adjustable in height automatically. Operationally, the adjustment of the filling level is thus obtained in a simpler and more reliable and less expensive manner compared to prior art solutions which require a pneumatic cylinder or an electric motor for each tube.

[0111] As already pointed out, this single cam 90 has an operating angle of working which covers only an extremely reduced portion of the circumferential development of the rotating carousel 10. This constitutes a further significant difference with respect to the prior art solutions which provide an annular cam or an abutment ring (essential if pneumatic cylinders are used) both having a circumferential development equivalent to that of the carousel. In practice, this single cam 90 is not in fact designed to maintain the tubes in the desired lowered position, but is only intended to bring the tubes to this lowered position, functional to level correction. The keeping of each individual tube in the lowered position imposed by the cam 90 is in fact assigned to the reversible blocking means 70, the actuation thereof can be controlled independently for each tube by means of the control logic unit 200.

[0112] Operationally, the return of each individual tube 16 to the raised position is instead carried out by the action of the elastic mechanical means 60, of which each valve group 13 is provided. The intervention of these elastic mechanical means 60 is commanded indirectly by acting on the reversible release means. The action of the elastic mechanical means 60 is in fact released when the reversible blocking means 70 are controlled to release by the logic control unit 200. The return of each individual tube 16 to the raised position is therefore obtained mechanically, but with the flexibility offered by an electro actuated control.

[0113] In practice, this allows extremely flexible management of the moment when the return air tubes 16 are lifted by means of the logic control unit 200. Potentially, the tube of each valve group can be raised differently from the others. This allows in particular optimizing the decompression step according to the type of container format used.

[0114] The filling machine 1 according to the invention offers greater reliability with respect to filling machines with pneumatic cylinders, due to the reduced complexity of the system for adjusting the filling level and handling of the tubes.

[0115] The number of components that actively intervene in the reliability of the system is in fact larger in a filling machine with pneumatic cylinders than in a filling machine according to the invention. The malfunction or incorrect assembly of a component can affect performance. For this purpose, two examples are given:

[0116] the changed friction conditions on one of the adjustment columns of the common abutment ring can cause not only the incorrect positioning of the ring in height but also the blocking thereof;

[0117] a fitting that is not correctly installed on the pneumatic lifting circuit of the tube could cause a loss of pressure which lowers the lifting force of the tube of all the valve groups if this circuit is common to all the pneumatic cylinders.

[0118] The constructive advantages ensured by the invention are also evident:

[0119] the movable upper part of the rotating carousel is freed from level adjustment systems to the advantage of maintenance and above all cleanability of this area; and

[0120] a level adjustment system (annular cam or abutment ring) which extends throughout the circumference of the carousel is substituted with a system (the cam 90 and the relative height handling means) much smaller and concentrated in a small peripheral zone of the filling machine.

[0121] In summary, the filling machine according to the invention meets the operating needs highlighted above (automatic adjustment of filling levels in case of format change and flexibility in the lifting of the return air tubes), in a simpler, more reliable and cost-effective manner compared to the currently available solutions.

[0122] The filling machine 1 is in fact capable of automatically and flexibly adjusting the filling level, adapting it to the format of the treated containers, as well as being able to automatically and flexibly manage the lowering of the return air tubes without being provided of a pneumatic cylinder or an electric motor for each tube.

[0123] Finally, the filling machine 1 according to the invention allows all filling valves to be adjusted to the same filling level without using a common abutment ring and without even providing each valve with an electric motor.

[0124] According to the embodiment illustrated in the accompanying figures, the cam 90 may be associated directly with the support structure 9 of the filling machine 1. In particular, the cam 90 may be associated with an anti-burst protection barrier 20.

[0125] Alternatively, the cam 90 may be associated with support elements separated from the support structure 9 of the rotating carousel 10.

[0126] Preferably, the means 100 for moving the cam 90 in height with respect to the support structure 9 comprise one or more electric motors 101.

[0127] More in detail, as illustrated in FIGS. 3 and 4, the means 100 for moving the cam 90 in height comprise: one or more guides 102 with a vertical axis, which slidably support the cam 90 in height; one or more electric motors 101 kinematically connected to the cam 90 by one or more screw-nut systems 103. This solution allows adjusting in a flexible and precise manner the height of the cam 90 and therefore of filling level of the containers, by means of the logic control unit 200, operatively connected to the electric motors 101. The height adjustment range of the cam is defined in the design phase by fixing the distance in height between the two end stops of the cam.

[0128] According to embodiments not illustrated in the accompanying figures, the means 100 for moving the cam 90 in height with respect to the support structure 9 may comprise other reciprocating systems alternative to the electric motors, such as for example pneumatic cylinders or connecting rod-crank systems.

[0129] According to the embodiment illustrated in the accompanying figures, the cam 90 is angularly fixed with respect to the entry station 3. In other words, the aforementioned first angular position 1 of the cam 90 is fixed. Operatively, this means that the lowering of the return air tubes 16 always takes place in the same angular position, without the possibility of adjustment.

[0130] This obviously does not constitute an operating limit when the filling machine 1 is intended to treat a single container format, since in this case the first angular position 1 may be optimally defined as a function of the filling cycle of the single container format treated.

[0131] The absence of adjustment of the first angular position constitutes, however, an operating limit in the much more probable case that the filling machine is intended to treat two or more different container formats.

[0132] However, this operating limit is not particularly relevant as will be clarified below. Conversely, a lack of flexibility in raising the return air tube could instead constitute an important operating limit, since it would prevent optimal management of the decompression step. However, the filling machine 1 according to the invention does not have this operating limit, sinceas already pointed outthe lifting of the tubes can be carried out flexibly by the logic control unit 200 since the return air tube 16 of each valve group 13 is operatively associated with reversible blocking means 70 and elastic mechanical means 60.

[0133] More in detail, in the (most probable) case in which the filling machine 1 is intended to treat two or more different container formats, the first angular position 1 will be chosen on the basis of a compromise between the requirements of the different container formats that will have to be treated by the filling machine, following the following two operational requirements:

[0134] the lowering of the tube, for each format, must take place before the filling of the bottle is finished: this requirement brings the angular position of the cam closer to the beginning of the working angle of the turret; and

[0135] the lowering of the tube, for each format, must take place towards the end of filling the bottle, to increase the protection of the tube from possible bursts during filling: this requirement leads to remove the angular position of the cam from the beginning of the working angle of the turret.

[0136] By analysing the various formats of containers to be processed by the filling machine, a compromise position is chosen, also taking into account the type of product associated with the various formats, with particular reference to the filling pressure. If a product is treated at low pressure, the protection of the tube is less important, since the risk of bursting is reduced. The main requirement is the first one (lowering before the end of the filling) because it affects the maximum productivity of the filling machine with the various formats, where filling end means the angular position in which the container is completely filled, result of both the filling time and the rotation speed of the turret.

[0137] Generally, the optimal individual angular positions for each different container format that can be treated by the filling machine 1 are in fact distributed in a narrow angular sector. This derives from the fact that if for a small format the filling is temporally shorter than a larger format, the small format will, however, generally be processed at a higher rotation speed of the carousel (in order to increase the filling machine productivity). For a larger format, the filling time will be longer, but at the same time the speed of the carousel will necessarily be lower in order to ensure completion of the filling cycle. The angular positions at the end of filling for the two different formats will therefore not differ much from each other. It follows that the first compromise angular position 1 is in fact very close to the first optimal angular position for each format. For these reasons, the lack of flexibility in the management of the angular position of the descent of the return air tubes does not constitute a particularly important operating limit.

[0138] According to an alternative embodiment not illustrated in the accompanying figures, in order to overcome also the partial operating limits related to the lower flexibility in the lowering of the tubes, the filling machine 1 may comprise means for angularly moving the cam 90 about the axis of rotation X of the carousel 10. In fact, these means allow the first angular position 1 to be varied with respect to the entry station 3 of the containers in the filling machine 1 as the format of the processed containers varies.

[0139] Preferably, the angular handling means of the cam 90 are electrically controllable and the logic control unit 200 is operatively connected thereto to automatically adjust the first angular position 1 of the cam 90 with respect to the entry station 3 of the containers in the filling machine 1. In this way, it is possible to position the cam 90 in the optimal angular position for each different container format processed by the filling machine 1.

[0140] Preferably, as illustrated in particular in FIGS. 6 to 11, the means 50 for guiding the axial movement of the return air tube (16) comprise:

[0141] one or more linear guides 51, which are constrained to the rotating carousel 10 and extend themselves between two end supports 52 which define the two end stops; and

[0142] a carriage 53, which is slidingly associated to said guides 51 and bears the cam follower 80, to which the tube 16 is rigidly constrained to move integrally therewith.

[0143] Advantageously, said one or more linear guides 51 are constrained to the rotating carousel 10 on the top 12 of the tank 12 to extend themselves in height outside said tank. The tube 16 is rigidly constrained to the carriage 53 at a portion thereof, which stays outside the tank 12. This configuration is advantageous as it ensures a more immediate maintainability of the system, being accessible from the outside.

[0144] Preferably, the elastic mechanical means 60 of each individual tube 16 are operatively associated to the axial guide means 50 and are suitable to Indirectly exert their thrust on the tube 16 acting on the carriage 53.

[0145] More in detail, as illustrated in particular in FIGS. 8 and 10, the carriage 53 is provided with a rod 54 rigidly fixed thereto to extend itself in height parallel to said one or more guides 51. Said elastic mechanical means consist of a mechanical coil spring 60 which is mounted coaxially to the rod 54 to act in thrust between said rod and a support 52 of said one or more guides 51.

[0146] Preferably, said rod 54 is axially inserted inside a protective sheath 55 intended to protect the rod from dirt deposit. In particular, said sheath 55 comprises at least an axially deformable portion 56 (for example, consisting of a bellows seal) and is associated with the rod 54, so as to ensure the protection of the rod 54 in any position.

[0147] Preferably, the reversible blocking means 70 of the return air tube 16 act on the rod 54 to reversibly block the axial movement thereof with respect to said one or more guides 51.

[0148] Preferably, the reversible blocking means consist of an electro-pneumatically actuated friction blocking device 70.

[0149] According to the illustrated embodiment of the accompanying Figures, and in particular in FIG. 11, said electro-pneumatically actuated friction blocking device 70 comprises an elastically deformable sleeve 71 mounted coaxially on said rod 54 inside a closed chamber 72 connected to a pressurised gas circuit (shown schematically in FIG. 11).

[0150] Operationally, the aforesaid sleeve 71 is susceptible to shift upon a variation of the internal pressure of the chamber 72 between:

[0151] a position of adherence to the rod, in which the sleeve 71 prevents the axial sliding of the rod 54 exerting thereon sufficient friction to overcome the action of the elastic mechanical means 60; and

[0152] a position of non-adherence, wherein the sleeve 71 permits the axial sliding of the rod 54 not exerting thereon sufficient friction to overcome the action of the elastic mechanical means 60.

[0153] Operationally, the passage between said two positions is controlled pneumatically by means of a solenoid valve 73 which is suitable to control the inflow of pressurised gas inside said chamber 72 and is operatively connected to the logic control unit 200.

[0154] Alternatively, the reversible blocking means may consist of an electro-mechanical or electro-magnetic blocking device.

[0155] Advantageously, each valve group 13 may comprise a level sensor, suitable for carrying out a first level definition with an alternative mode to the hydraulic one through the return air tube. Preferably, such a level sensor is associated with the return air tube 13 and is thus moved together with it. Operatively, the correction of the filling level by means of the return air tube is in any case carried out.

[0156] Preferably, the filling machine 1 is an isobaric filling machine. The logic control unit 200 is programmed in such a way that depending on the format of container handled by the filling machine 1 the second angular position 2 is chosen ensuring that the return of the tube to the raised position occurs before a decompression phase of the container.

[0157] The invention thus conceived thus achieves the intended purposes.