A PROCESS FOR FILLING CONTAINERS, IN PARTICULAR CANS, WITH LIQUIDS, AND A FILLER VALVE GROUP FOR CARRYING OUT THE PROCESS

Abstract: The invention relates to the field of processes and plants for filling cans (10) with liquids. The filling process envisages a contemporaneous closure of the liquid and gas inflow pipes (12 and 13). The invention also refers to a filler valve group (1) wherein the pipes (12 and 13) are placed at the same level. A cam (14) permits the rising or descent of the cans (10) with respect to the valve group (1) in order to regulate the filling level.

Description: A Process for filling Containers, in particular Cans, with Liquids, and a Filler Valve Group for Carrying Out the Process. Description. The invention relates to a process for filling containers, in particular cans, with liquids, and a filler valve group for achieving the said process. In the field of container liquid filler groups, and especially in the case of can fillers, filler machines with rotating platforms having a plurality of filler valve groups to fill transiting containers are well known. Generally the containers are supported on non-vertically- mobile plates and during the filling phase the valve group descends towards the container, or, as in other prior art realisations, the valve group is fixed and the containers are brought upwards to them by vertically-mobile plates. In the majority of can filler machines for carbonated liquids, the liquid level in the cans is defined by means of a level-sensing tube, which during the filling phase is partially introduced into the can. The liquid inflow into the can is stopped at the moment when the liquid reaches and closes the lower opening of the tube, causing the gas to flow towards the container tank. Obviously correct and precise dimensioning of the level- sensing tube is important since every millimetre of vertical level in the can corresponds to about three cubic centimetres of liquid. One drawback of traditional fillers lies in the fact that it is difficult to maintain level precision over a long period of time, as accuracy can be compromised by accidental impacts between the level-sensing tube and the can at the inlet and outlet zones of the machine. The tube suppoort in the filler valve is indeed small since its size is conditioned by the passage section of the liquid, which must be as large as possible. A further drawback is the difficulty of sensing tube height regulation when the can shape is changed, or when the filling level required is varied. In prior art filler machines intervention is required on the single valves to effect such a regulation, causing hold-ups and loss of time, as is shown for example in International Patent WO 90/08727. A further drawback in traditional valves is the fact that uncontrolled variation in the liquid level occurs, and therefore the quantity of the contents in the can changes, caused by variations of pressure and/or product level in the tank. When the liquid closes the level-sensing tube in the can, some pressurised gas remains trapped between the valve body and the surface of the liquid so that if in the meantime the pressure in the tank increases, even by a few tenths of a bar, the liquid is pushed into the can in order to reestablish the isobar equilibrium between the tank and the can, causing an undesired increase in the contents of liquid in the can. This phenomenon is particularly relevant when the filler machine halts while there are containers actually in the filling phase: traditional filler machines in such conditions tend to fill the containers almost to the top. In order to limit the above-mentioned drawbacks, conventional filler machines have, on the path of the liquid, syphons, nets or small holes, which however make the valve group considerably more complex and difficult to clean and sterilise, and which do not in any case fully solve the problem. One realisation in particular, illustrated in German Patent DE 2 120 554, envisages the use of a tube surrounded by a sort of float with which it can run vertically for a tract internally to the valve group so as to permit the closure of the liquid inlet pipe. In reality, apart from the complexity of the device, when the liquid reaches the lower end of the tube, closing the gas pipe, the liquid pipe stays open and, with the outflow of the residual liquid from the pipe the level of the liquid in the container rises, causing a similar raising of the level sensing tube together with the float, up unitl the float completely closes the liquid inlet pipe. But, since the closure is caused by the inflow of liquid, it follows that the more the inflow pipe is obstructed by the float, the slower the rising of the float will be, and final closure is thus delayed. Document DE 2 042 990 shows a filler valve group equipped with a height-mobile centering element externally to the valve and solid to the level- sensing tube. This document does not, however, teach how to solve the above-mentioned problems connected with the presence of the level sensing tube. US Patent 4,986,318 shows a filler valve for can filling under counterpressure, wherein the seal between the valve and the can is obtained by means of two ring gaskets or "O rings" which are concentric and superposed one on the other, and wherein there is a final decompression due to increased volume inside the can due to the extraction of the can at the end of the filling operation. This decompression, however, is not guaranteed by the O-rings, which are subject to frequent stress during the entrance and exit of the cans for each filling operation, causing rapid wear and tear. Neither does this document solve the other drawbacks connected with the presence of the level-sensing tube. The principal aim of the present invention is to obviate the above-mentioned drawbacks by providing a filling process and a valve group which avoid the use of a level-sensing tube, which are versatile and reliable, and which have a single external command for regulation of the liquid content in the cans. A further aim is to achieve greater precision in the levels, with a simplification of the valve group and at the same time a shorter filling time and thus greater productivity, and which also reduces foam formation during the decompression phase. The said aims are all attained in the invention, which is a process of container filling, in particular cans, with liquids, which is characterised as in the claims that follow, and in particular in that the opening of the liquid and gas valve occurs when the inferior end of the gas and liquid inflow pipes are at the same level, so that when the liquid level in the container closes the gas pipe, it contacts also the liquid inlet pipe. Further characteristics and advantages of the present invention will better emerge from the detailed description that follows, of an embodiment of the invention, herein illustrated purely in the form of a non-limiting example in the accompanying figures, in which: - figure 1 schematically shows the valve group in the various process phases; figures 2 and 3 show, in section and in two different operative phases, the container lifting means; - figures 4 and 5 show a detail of the means of figures 2 and 3 in a sectioned view according to line I-I of figures 2 and 3; figure 6 shows, in vertical section, a filler valve group; - figures 7 and 8 show the various phases of the process according to two different operative sequences. With reference to the figures 1 denotes in its entirety a filler valve group of a container liquid filler machine 10. In the description, specific reference will be made to cans, but the invention can be applied to other kinds of containers. The filler machine is conventionally of the rotating platform type 6 equipped with a plurality of filler groups. A lifting group 2 is associated to each valve group 1 and supports a plate 5 destined to receive a can 10. In the examples in figures 1 to 7, a cam 15 regulates, by means of a roller 16, the vertical movement of the plate 5 coaxially to valve group 1. A mechanical pivot 7 can block the lifting group 2 in the position defined by the cam 15, by inserting into a recess 30 in the lifting group 2. The lifting group 2 constitutes a lifting means of the can 10 towards the valve group 1. The valve group 1 comprises an obturator or valve 11 in the shape of a tubular stem, which regulates the influx of liquid in a pipe 12, from a container tank 29 to the can 10. Apart from the filling liquid, there is also a pressurised gas in the tank 29, occupying the free space above the liquid. A spring 19 regulates the aperture of the valve 11, pushing it upwards and freeing the pipe 12. The valve 11 is housed in a cylindrical housing 17 and is internally hollow. Gas or return air passes through the internal pipe 13 of the valve 11, the flow of which is regulated by a valve 9 activated by a mechanical positioner 8. The internal pipe 13 is made entirely internally to the tubular stem of the valve 11 and opens at the inferior end of the tubular stem. The valve group 1 is inferiorly provided with a centering element 3 which sealingly engages the mouth of the can by means of a gasket 4. The centering element 3 can rise externally to the valve group 1, together with the can, so that the inferior end of the valve group 1 can penetrate into the can 10 itself. With particular reference to figure 1, where in letters A to H the various operative phases of a filling cycle are shown, in the diagrams below the main illustrations the angular positions of the rotating platform 6 corresponding to the single phases are shown. The process of the invention envisages the following operative phases: A - The empty can 10, entering the filler machine, is positioned on a plate 5 of the lifting group 2 coaxial to the valve group 1, the plate 5 being at the bottom dead centre and the centering element 3 being raised so as to enable the can 10 to be positioned below it. Then the centering element 3 lowers on to the can 10, as can be seen in the figure, up until the mouth of the can 10 couples with the gasket 4 of the centering element 3. B - The cam 15, through the lifting group 2, causes the can 10 to rise, together with the centering element 3, externally to the valve group 1, which thus penetrates inside the can 10. In the meantime, the mechanical pivot 7 blocks the lifting group 2 in the position defined by the cam 15. A mechanical force acting in the direction of arrows 18 keeps the centering element 3 pushed downwards, in order to preserve the seal between the centering element 3 and the can 10. The force, as is illustrated in figure 6, is realised by the immission of compressed air into a pipe 26 which opens into a chamber 27 so as to push a support 28 of the centering element 3 downwards. In a further embodiment (not illustrated) the downwards push exerted on the centering element 3 is obtained by using special elastic means, such as for example springs. C - The activation of the mechanical positioner 8 causes the gas valve 9 to open and when the pressure inside the can 10 is equal to that in the tank, the spring 19 causes the valve 11 to raise and the consequent inflow of liquid into the can 10 through the pipe 12, while the gas returns into the tank through the internal pipe 13. Both ends of the pipe 12 and internal pipe 13 are at the same level. D - When the liquid in the can 10 reaches a predetermined level (coinciding with the inferior end of the internal pipe 13), indicated in the figure by arrow 20, which is below the final level desired, the inflow of liquid stops as it closes both the internal pipe 13 and the pipe 12. E The pivot 7 reenters and frees the lifting group 2 which then can descend along a lowering cam 14, with the gas valve 9 and the valve 11 still open. Fl - Mechanical closure of the gas valve 9 and the valve 11 by activation of the positioner 8 and with the liquid (denoted by arrow 21) reaching its desired level in the can 10, which level is above that of phase D since during the can's descent, with the gas valve 9 and the valve 11 still mechanically open, the pipe 12 and internal pipe 13 positions have risen in relation to the can 10. The positioner 8 command is external to the machine, and is fixed and single for all of the valve group 1. F2 - This phase of the cycle shows the extreme simplicity with which a change in the level of the liquid, and thus the quantity of contents in the can, are obtained. It is enough to change the mechanical closing point of the valve 9 and the valve 11 along the inclined tract of the lowering cam 14 to obtain a different level. In the illustrated case, the difference between the level indicated by an arrow 22 and the preceding level indicated by arrow 21 is equal to the lowering of the lifting group 2 indicated by arrow 23. In a further embodiment (not illustrated) the filling level change can be obtained by changing the inclination of the lowering cam 14, and keeping the positioner 8 intervention point fixed. This happens by using special means, constituted for example by a lowering cam 14 pivoted at one of its ends while its other end is adjustable to various height levels. G - After being closed as in Fl or F2, the lifting group 2 follows its lowering journey along the cam 14; the valve group 1 is removed from the can 10, increasing the free volume and initialising the decompression of the can without placing the free space in communication with the outside atmosphere. At the end of the this phase the residual pressure value in the can depends on the filling pressure value. The can decompression continues with the activation of a button 24 which causes the opening of a valve that places the inside of the can in communication with the outside atmosphere through a pipe 25 opening at one end inside the centering element 3 and at the other end into the external atmosphere. H - The lifting group 2 returns into a position at the lower start-cycle level and the centering element 3 is partially raised by a cam acting on a roller 31 to permit the can to exit from the filler machine. With reference to the process variation illustrated in figure 7, phases A, B, C and H stay the same, while the other phases are substituted by the following: D- When the liquid in the can reaches a prefixed level (coinciding with the inferior end of the internal pipe 13), denoted in the figure by an arrow 20 and above the final desired level, the inflow of the liquid stops since it closes both the internal pipe 13 and the pipe 12. E - The pivot 7 reenters and frees the lifting group 2 which is pushed upwards by means of a cam 14, with the gas valve 9 and the valve 11 still mechanically open. The excess product flows back into the tank through the pipe 12 and thus a level correction is performed, the liquid in the can 10 now being at the desired level, indicated with an arrow 21, the level being lower than that of phase D. It is enough to change the height position of the cam 14 pivoted at 32 to obtain, with extreme simplicity, a corresponding change in the can liquid level. In a possible further embodiment (not illustrated) the cam 14, rather than being pivoted at 32 can translate in height parallel to itself to obtain a change in the level of liquid in the can. Fl - Mechanical closure of the gas valve 9 and the valve 11 (at the macimum upper point of the cam 14 by means of activation of the positioner 8. F2 - After clusre at Fl the lifting group 2 follows a descent course along cam 14; the valve group 1 disengages from the can 10, thus increasing the free volume and initialising the can decompression without placing the free space in communication with the outside atmosphere. At the end of this phase the residual pressure value in the can 10 depends on the filling pressure value. G - The can decompression continues by means of the activation of a button 24 which causes opening of a valve placing the inside of the can 10 in communication with the outside atmosphere through a pipe opening at one end inside the centering element 3 and at the other end into the outside atmosphere. In figure 8 a further phase sequence of the process is shown, wherein, with respect to the sequence of figure 7, phase B is missing and thus the can 10 is not lifted by the lifting group 2, nor blocked by the pivot 7, since the pivot 7 and the lifting cam 15 are absent: the filling occurs with the can in a not-raised position with respect to the loading plane. In this case phases c and D are substantially the same as the preceding case, as are phase E (except that the pivot is missing) and phases Fl, F2, G and H. The absence of the level-sensing tube from the invention, being replaced by a gas pipe 13 which is completely internal to the valve 11 of the liquid influx pipe, permits of avoiding the problems connected with the use of the sensing tube and ensures greater precision in the filling levels, as the liquid contemporaneously closes both the internal pipe 13 and the pipe 12, thus preventing further inflow of the product into the can 10. In a further embodiment (not illustrated) the inferior end of the gas internal pipe 13 can be at a higher level with respect to the inferior level of the liquid pipe 12. A great advantage is that the level of the product in the cans can be changed by a single command, external to the filler machine: this is a rapid and reliable operation if we compare it to the traditional substitution of single level sensing tubes for each valve group 1. The decompression of the can created by the increase in the free space determined by the descent of the can with respect to the valve group 1 permits of large reduction in counterpressure gas consumption, smaller loss of gas into the atmosphere and less foam. A reduction in the foam can be obtained also by means of the correction of the level effected in phase E of figures 7 and 8, by making it so tha the liquid level is corrected by reduction rather than increase, with a partial reflow of the excess liquid into the tank. The initial more-or-less total filling of can brings about a natural limitation of foam formation as well as a more precise correction. The absence of syphons or nets or small holes along the liquid inflow pipe in order to avoid the overfilling of the can 10, allows larger inflow volumes to be introduced and therefore decrease filling time.

Claims: Claims 1. A process for filling containers, in particular cans, comprising phases of: - a sealed coupling between a mouth of a container (10) and a filler valve group (1), after a lifting of the container (10) towards the filler valve group (l) ; - an opening of a gas valve (9) and a liquid valve (11) and a subsequent closing of the same once filling has been effected; a detachment between the container (10) and the valve group (1) , characterised in that the liquid valve (11) and gas valve (9) open when inferior ends of gas inflow pipes (13) and liquid inflow pipes (12) are positioned at a same level, so that when a liquid level in the container (10) closes the gas pipe (13), the liquid level also comes into contact with the liquid inflow pipe (12). 2. A process for filling containers, in particular cans, with liquids, comprising phases of: - a sealed coupling between a mouth of a container (10) and a filler valve group (1), after a lifting of the container (10) towards the filler valve group (l) ; - an opening of a gas valve (9) and a liquid valve (11) and a subsequent closing of the same once filling has been effected; - a detachment between the container (10) and the valve group (1) , characterised in that the opening of the gas valve (9) and the liquid valve (11) occurs when an inferior end of a gas inflow pipe (13) is higher than an inferior end of a liquid inflow pipe (12), so that when liquid flowing into the container (10) reaches and closes the liquid inflow pipe (12), the gas pipe (13) remains open. A process as in claim 1, characterised in that when the liquid level in the container (10) reaches both the gas pipe (13) and the liquid pipe (12), when the gas valve (9) and the liquid valve (11) are still mechanically open, a liquid level correction phase in the container occurs, by means of a gradual and adjustable change in a height position of the container (10) with respect to the valve group (1), the size of the change being in accordance with the required level of liquid in the container (10). 4. A process as in claim 3, wherein the liquid correction phase occurs by raising the container (10) with respect to the valve group (1), the size of the rise being in accordance with the required level of liquid in the container (10). 5. A process as in claim 3, wherein the liquid level correction occurs by means of a gradual and adjustable descent of the container (10) with respect to the valve group (1), the size of the descent being in accordance with the desired liquid level in the container (10). 6. A process as in one of the previous claims, wherein, after closing the gas valve (9) and the liquid valve (11), an adjustable and gradual descending phase of the container (10) occurs with respect to the valve group (1), the said descent causing a decompression internally to the container (10) due to an increased free volume. A filler valve group (1) for a filler machine of containers, in particular cans, comprising: - a valve (11) in a shape of a tubular stem for a liquid inflow pipe (12), to regulate the liquid inflow from a container tank to a container (10) arranged coaxially below the valve (11); - a valve (9) of a pipe (13) for gas or air, said pipe (13) being partially internal to the tubular stem, characterised in that the gas or air pipe (13), during a filling phase, is totally inside the valve (11) of the liquid pipe (12) and has an opening at an inferior end of the valve (11), or a higher position. A filler valve group (1) in a filler machine of containers (10), in particular cans, with liquids, comprising: a valve (11) in a tubular stem shape for a liquid inflow pipe (12), to regulate the liquid inflow from a container tank to a container (10) arranged coaxially below the valve (11); - a valve (9) of a pipe (13) for gas or air, said pipe (13) being partially internal to the tubular stem, characterised in that during a filling phase of the containers (10), inferior ends of the liquid and gas inflow pipes (12 and 13) are at a same level, so that, when the liquid in the container (10) reaches and closes the gas inflow pipe (13), it also contacts the liquid inflow pipe (12). 9. A valve group (1) as in claim 7 or 8, characterised in that it is provided with a mobile centering element (3) which surrounds the inferior end of the valve group (1), and is normally loaded in a downwards direction and creates a seal with a mouth of the container (10) when the container (10) is pushed towards the centering element (3) by a lifting group (2) up until it causes the raising of the centering element (3) about the valve group (1), and a partial insertion of the tubular stem in the container (1). 10. A filler valve group (1) as in claim 9, characterised in that the lifting group (2), activated by a cam (15), comprises a mechanical pivot (7) to block the lifting group (2) in a work position. 11. A filler valve group (1) as in claim 7 or 8, characterised in that it comprises a positioner (8), which command is external to the filler machine and is one alon for all of the valve groups (1) of the filler machine, and opens or closes the gas valve (9) and closes the liquid valve (11). 12. A filler valve group (1) as in claim 11, characterised in that it comprises a cam (14) which regulates the descent of the container (10) with respect to the valve group (1) so that by means of a retarded (or anticipated) activation of the positioner (8) to close the pipes (12 and 13), a higher (or lower) final level of liquid in the container (10) is achieved. 13. A filler valve group as in claim 7 or 8, characterised in that it comprises a cam (14) regulating a descent of the container (10) with respect to the valve group (1), the cam (14) comprising means which permit of regulating the inclination with respect to a horizontal plane.

Inventors: CONFORTI LUCIO, CONFORTI, LUCIO
Applicants: CONFORTI LUCIO, SIMONAZZI SPA, CONFORTI, LUCIO, SIMONAZZI S.P.A.
Application year: 1993
Main classification: B67C3
IPC codes: B67C3