Abstract:
A method for filling containers simultaneously with the filling-material sealing the containers against filling heads at the filling positions, and using a filling-material volumetric-flow-rate controller common to all of the filling positions to control flow of filling-material as a function of a target filling-curve by executing a filling phase with intervals that have different flow rates and controlling transition times between these intervals to ensure that each container finishes the filling phase with the correct amount of filling-material.

Description:
RELATED APPLICATIONS 
       [0001]    This application is the national stage under 35 USC 371 of international application PCT/EP2014/062427, filed on Jun. 13, 2014, which claims the benefit of the Jun. 27, 2013 priority date of German application DE 102013106756.5, the contents of which are herein incorporated by reference. 
     
    
     FIELD OF INVENTION 
       [0002]    The invention relates to filling containers, and in particular, to filling containers according to a target filling-curve. 
       BACKGROUND 
       [0003]    In the container processing industry, it is known to fill relatively large-volume keg-like containers or kegs, during a filling phase of a filling process. It is also known that the amount of filling-material flowing into the keg should be controlled. Known methods involve using a volumetric flow-rate controller or filling-material volume controller, and controlling as a function of a filling curve stored in a control computer. 
         [0004]    A disadvantage of known methods is that kegs are filled one at a time. 
       SUMMARY 
       [0005]    An object of the invention is to present a method for simultaneously filling two or more containers with the required filling precision using only a single filling-material flow controller, and specifically by taking account of a target filling-curve. 
         [0006]    A particular feature of the method according to the invention is that, with only a single filling-material volumetric flow-rate controller, the simultaneous or temporally parallel filling of at least two containers, and preferably of more than two containers, takes place via filling heads, of which in each case one is allocated to each container. Since in practice, with regard to the filling-material volume flow that flows into the individual containers or to the filling heads during the filling phase, it is not possible to achieve absolutely the same conditions, the invention makes provision that the control of a total filling-material volume flow, and therefore of the filling-material volume flows to the filling heads, does indeed generally take place by way of the individual filling-material flow controller, but each filling-material volume flow flowing to a container is monitored by an independent flow-meter, and, with the measurement result from this flow-meter, this flow is corrected. 
         [0007]    The general controlling of the filling-material volumetric flow-rate controller is carried out in accordance with a target filling-curve, which is either a standardized filling curve or a filling curve specific to a filling-material and/or specific to a container. 
         [0008]    By way of the method according to the invention, a substantial simplification of the filling system in terms of design and technical control aspects can be achieved by reducing the number of function elements required. In particular, only a single filling-material volumetric flow-rate controller is required, and, for example, also only a single filling-material pump for the provision of the filling-material, and specifically despite the possibility of simultaneously filling at least two containers, but preferably more than two containers, with the degree of filling precision required. 
         [0009]    With the method according to the invention, the containers have preferably a container or filling volume in the range of between three and ten liters. If the target filling-curve exhibits part phases with differing volume flows, the correction control takes place, for example, by moving the point in time of the transition between individual part phases. In any event, however, on the basis of the measured values from the flow-meters, a final termination of the filling or filling phase for each container is reached when the required total filling volume has passed into it. 
         [0010]    In a further embodiment of the invention, the method is arranged, for example, such that, by means of the control computer, on the basis of the measured values provided to it from the flow-meters, a temporal displacement of the transition between at least two part phases of the target filling-curve is effected, for example between the filling phase with the reduced filling-material volume flow (Q 1 ) and the quick filling phase with the increased filling-material volume flow (Q 2 ) and/or between the quick filling phase and the end filling phase, and/or that, by means of the control computer, on the basis of the measured values provided to it from the flow meters, a temporal displacement of the ending of the filling phase takes place, and/or that the control computer monitors the individual actual filling curves in parallel, and, taking the results of the comparison with the target filling-curve as a starting point, controls the filling process or the filling-material volumetric flow-rate controller respectively, and/or that the correction of the actuation of the filling-material volumetric flow-rate controller takes place by a comparison of the filling-material volume flow acquired by the flow-meters and the corresponding actual filling curves at the containers with the target filling-curve deposited in the control computer, and that, in the event of a deviation, the correction of the actuation of the filling-material volumetric flow-rate controller takes place, for example by the time of the transition between at least two sub-phases of the desired filling curve, and/or that, on the basis of the measured values provided by the flow-meters, the control computer only carries out a temporal switchover from the filling phase to the quick filling phase when the minimum filling-material quantity has also been introduced into those containers of which the filling is slowest, which was delivered at the beginning of the quick filling phase, and/or that the switchover from the quick filling phase to the subsequent phase then takes place with a reduced or reducing filling-material volume flow (Q 3 ), for example to an end filling phase, when that container into which the filling-material flows at the greatest flow-rate is filled with the filling-material quantity required at the end of the quick filling phase, and/or that, with a counter-pressure filling of the containers pre-tensioned with a tensioning gas, the return gas forced by the liquid filling-material out of the containers is conducted via a return-gas line, common to all the filling points, in which a return gas regulator is provided in order to maintain a constant return gas pressure, and/or that with the pressure filling of a filling-material containing CO 2 , the tension gas pressure and/or the return gas pressure lies slightly above the CO 2  equalizing pressure of the filling-material, amounting, for example, to 1.5 bar, and/or that for the actuation of the filling-material volumetric flow-rate controller a target filling-curve specific to a product and/or a container is used, wherein the features referred to heretofore can be used in each case individually or in any desired combination. 
         [0011]    In one aspect, the invention features a method for filling containers simultaneously with the filling-material, wherein filling containers simultaneously by placing the containers at corresponding filling positions, sealing the containers against filling heads at the filling positions, and, using a filling-material volumetric-flow-rate controller that is common to all of the filling positions, controlling flow of filling-material as a function of a target filling-curve. Controlling flow using the filling-material volumetric flow-rate controller includes at a first transition time, beginning a filling phase by causing filling-material to flow at a first flow-rate, thereby beginning a first interval of the filling phase, at a second transition time, increasing the first flow-rate to a second flow-rate, thereby ending the first interval and beginning a second interval of the filling phase, at a third transition time, reducing the second flow-rate to a third flow-rate, thereby ending the second interval and beginning a third and final interval of the filling phase, and at a fourth transition time, ending the filling phase. During the filling phase, actual filling-curves associated with each of the containers are measured, and, based at least in part on these measured actual filling-curves, a control computer implements a correction to cause equal volumes of filling-material to be in each container upon completion of the filling phase. 
         [0012]    In some practices, causing a control computer to implement a correction includes causing a temporal displacement of either the second transition time, the third transition time, or possibly both. 
         [0013]    In other practices, causing a control computer to implement a correction includes causing a temporal displacement of the fourth transition time. 
         [0014]    Some practices include causing the control computer to measure the actual filling-curves in parallel. Among these practices are those that also include comparing the actual filling-curves with the target filling-curve, detecting a deviation between at least one actual filling-curve and the target filling-curve, and, in response, causing a change in at least one of the transition times. 
         [0015]    Among the containers, there exists a last container that fills more slowly than all others of the containers. In some practices, the method further includes causing a transition between the first interval and the second interval only when a minimum filling quantity required at the beginning of the second interval has been introduced into the last container. 
         [0016]    During the second interval, there exists a first container that fills faster than all other containers. Some practices include switching from the second interval to the third interval only when a filling-material quantity required at the end of the second interval has been filled into the first container. 
         [0017]    Yet other practices include pre-tensioning the containers with tensioning gas, conducting away return gas via a return gas line common to all of the filling positions, and maintaining a constant return gas pressure using a return gas regulator. 
         [0018]    In some practices, the filling-material is carbonated. In these practices, either a tension gas pressure or a return gas pressure is maintained to above the filling-material&#39;s CO2 balance pressure, for example, 1.5 bar above the balance pressure. 
         [0019]    Practices of the invention also include those in which the target filling-curve is selected to be specific to the container, those in which it is selected to be specific to the filling-material, and those in which it is selected to be specific to the combination of container and filling-product. 
         [0020]    In another aspect, the invention features an apparatus for simultaneously filling containers with liquid filling-material. Such an apparatus includes a control computer, a filling-material volumetric flow-rate controller, filling positions, and branched product lines connecting the filling positions to the controller. Each of the filling positions has a filling head, a tension valve, a liquid valve, a return-gas valve, and an independent flow meter in a product line leading to the filling head. The control computer actuates the controller according to a target filling-curve. The controller then controls filling-material volume flow to the filling positions as a function of a target filling-curve that is stored on the control computer. The target filling-curve defines a filling phase that consists of three intervals, each with its own flow rate. These intervals follow each other in sequence with the second being between the first and third. Among the flow rates, that of the second interval is the greatest. 
         [0021]    In some embodiments, each filling head further comprises a filling pipe that is configured to be extended into a container to be filled. 
         [0022]    Other embodiments include a common tension gas line, a common return gas line, and a return gas regulator, and a pressure sensor, both of which are along the common return gas line. The tension valves of the filling heads all connect to the common tension gas line, and the return gas valves of the filling heads all connect to the common return gas line. The return gas regulator maintains constant return gas pressure in the return gas line based at least in part on a pressure signal provided by the pressure sensor. 
         [0023]    In some embodiments, the controller, the branched product lines, and the filling positions define a preassembled component unit that is configured to be mounted on a filling machine. 
         [0024]    Further embodiments, advantages, and application possibilities of the invention are also derived from the following description of embodiments and from the figures. In this context, all the features described and/or pictorially represented are, by themselves or in any desired combination in principle the object of the invention, regardless of their inclusion in the claims or reference to them. The contents of the claims are also constituent parts of the description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    These and other features and advantages of the invention will be apparent from the following detailed description and the accompanying figures, in which: 
           [0026]      FIG. 1  shows a filling system for the simultaneous or parallel filling of plural containers; 
           [0027]      FIG. 2  shows a filling position of the filling system from  FIG. 1 , together with a container arranged in the sealed position at a filling head or filling element thereof; 
           [0028]      FIG. 3  shows a filling curve to be followed during the filling of the containers at the filling position of  FIG. 2 ; 
           [0029]      FIG. 4  shows a branching structure used in the system of  FIG. 1 ; and 
           [0030]      FIG. 5  is a perspective view of a portion of the system shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0031]      FIG. 1  shows a filling system  1  that is a constituent part of a filling machine. The filling system  1  simultaneously pressure fills four containers  2  with filling-material. An example of a filling-material is one that contains CO 2 , such as beer. The containers  2  are preferably cans, such as party cans, or kegs with large volumes. Examples of large volume containers include three-liter containers, five-liter containers, and ten-liter containers. 
         [0032]    The filling system  1  forms four filling positions  3 . 1 - 3 . 4 . During filling, each filling position  3 . 1 - 3 . 4  has a container  2  standing upright on its base on a container carrier  4  with its container opening facing upwards and its container axis vertically oriented. Each container  2  is also arranged so that a seal  5 . 1 , best seen in  FIG. 2 , seals it against the filling head  5 . 
         [0033]    Referring to  FIG. 2 , each filling head  5  has a liquid valve  6 , a tension-gas valve  7  that opens on an outlet side, a return-gas valve  8 , and a filling pipe  9 . 
         [0034]    The liquid valve  6  transitions between an open state and a closed state. In the open state, filling-material flows into the container  2 . In the closed state, the liquid valve  6  interrupts inflow of filling-material into the container  2 . 
         [0035]    During filling, the filling pipe  9  extends deep into the container&#39;s interior. It is through this filling pipe  9  that filling-material flows during container filling. An upper end of the filling pipe  9  connects to a liquid channel formed in the filling-material head  5  in which the liquid valve  6  is arranged. 
         [0036]    The return-gas valve  8  has an inlet that connects to a head space that forms in the container&#39;s interior as it fills and an outlet that connects to a return gas pipe  23 . 
         [0037]    A pump  10  conducts filling-material to the filling heads located at the filling positions  3 . 1 - 3 . 4 . The pump&#39;s delivery capacity and output pressure can be regulated or controlled, preferably continuously rather than in discrete steps. In some embodiments, the pump  10  has a drive motor whose speed and/or torque can be regulated or controlled by a frequency converter. 
         [0038]    On its inlet side, the pump  10  connects to a filling-material tank that provides filling-material. On its outlet side, the pump  10  connects to a product line  11 . The product line  11  continues to a first branching-structure  12 . At the first branching-structure  12 , the product line  11  divides into a pair of first branches  13 . Each of the first branches  13  continues to a second branching-structure  14 . At the second branching-structure  14 , each of the first branches  13  then divides into a pair of second branches  15 . Each of the resulting second branches  15 , of which there are now four, proceeds to a filling head  5  and to a liquid valve  6  located therein. 
         [0039]    In the course of the multiple branching, there is a corresponding stepped reduction of the effective cross-sections of the first branches  13  in relation to the product line  11  and of the second branches  15  in relation to the first branches  13 . This corresponding stepped reduction is selected so that, when the liquid valves  6  open in the filling phase, the volume rate of flow of filling-material in all the second branches  15 , as well as through all the filling-material heads  5 , is the same or very close to the same. 
         [0040]    One way to achieve the stepped effective flow cross-section of the first and second branches  13 ,  15  is to use pipelines having diameters that have been selected to achieve desired inner cross-sections. Another method, which enables the use of any size pipe, is to provide a choke as needed to choke the flow of filling-material. 
         [0041]    Producing the stepping of the effective cross-section of the first and second branches  13 ,  15  with corresponding stepping of the inner cross-sections of the pipes forming these branches results in a static pressure inside these pipes. This static pressure leads to almost identical flow and pressure conditions prevailing at all the filling heads  5  and at their filling-material outlet openings or mouths. 
         [0042]    The first and second branching-structures  12 ,  14  are similar enough so that the reference numerals for both are shown in  FIG. 4 . Each branching structure  12 ,  14  is preferably a Y-shaped branch. 
         [0043]    A pressure sensor  16  in the product line  11  downstream of the pump  10  constantly monitors the pressure of the filling-material inside the product line  11  and sends a sensor signal indicative of this pressure to a control computer  17 . 
         [0044]    Based at least in part on this sensor signal, the control computer  17  operates the pump  10  in a way that results in a constant or essentially constant filling-material pressure in the product line  11  at the outlet of the pump  10 . This filling-material pressure is, as much as possible, independent of fluctuations in the filling-material volume flow during the filling of the containers  2 . 
         [0045]    The combination of the pump  10  and the pressure sensor  16  ensures proper delivery of filling-material even without a filling-material tank, and in particular, even without a filling-material tank in which the filling-material is provided at a level above the filling heads  5 . 
         [0046]    A volumetric flow-rate controller  18  upstream of the first branching structure  12  controls total filling-material volume flow during the filling phase. In particular, the flow-rate controller  18  controls filling-material flow in accordance with a program stored in a memory of the control computer  17 . Such a program is specific to a filling-material and/or to a container. An example of such a program is a target filling-curve that shows flow-rate as a function of time, as shown in  FIG. 3 . 
         [0047]    In some embodiments, the flow-rate controller  18  is a pneumatically actuated. In other embodiments, the flow-rate controller  18  is a DFC controller. 
         [0048]    Some embodiments of the flow-rate controller  18  feature a diaphragm that delimits a filling-material channel or thruway located therein. Subjecting the diaphragm to pneumatic control pressure changes an opening cross-section that is available for the filling-material to flow through. This provides a way to control flow of the filling-material as a function of this control pressure. 
         [0049]    The control computer  17  controls the flow-rate controller  18  via an I/P converter  19  that converts the electrical control signal from the control computer  17  into the control pressure that ultimately actuates the rate controller  18 . Thus, throughout this description, when the flow-rate controller  18  is said to perform an act, it is understood that it does so as a result of control exerted by the control computer  17 . 
         [0050]    Each second branch  15  has an independent flow meter  20  that delivers an electrical measurement signal indicative of filling-material volume flow through that second branch  15 . In some embodiments, the flow meter  20  is a magnetic-inductive flow meter. The measurement signals from the flow meter  20  are likewise sent to the control computer  17  for the control and correction of the filling process in the manner described in greater detail hereinafter. 
         [0051]    As shown in  FIG. 1 , the tension-gas valves  7  of all the filling heads  5  connect on their respective inlet sides to a common tension gas line  21 . A tension gas maintained at a tension gas pressure fills the tension gas line  21 . Examples of a tension gas include an inert gas, CO 2  gas, nitrogen, or sterile air. A tension-gas arrangement  22  connected to a source of tension gas controls the tension gas pressure. 
         [0052]    The filling heads  5  can also be subjected to a flushing gas in the manner described above. In this situation, a distinction exists between the flushing gas and the tension gas, as well as between the flushing-gas pressure and the tension-gas pressure. 
         [0053]    Each return-gas valve  8  has an outlet that connects to a common return-gas line  23 . A pressure sensor  24  on the return-gas line  23  constantly measures the return gas pressure in the return-gas line  23  and provides an output signal indicative of that pressure to the control computer  17 . 
         [0054]    A return-gas controller  25  lies downstream of the pressure sensor  24  along the return-gas line  23 . In some embodiments, the return-gas controller  25  is a pneumatic controller that is actuated by a pneumatic control pressure that is controlled by the control computer  17  as a function of the measurement signals from the pressure sensor  24 . An I/P converter  26  converts the pressure measurement into a signal suitable for delivery to the control computer  17 . The control computer  17  actuates the return-gas controller  25  in an effort to maintain a constant return gas pressure in the return-gas line  23  is constant. 
         [0055]    After passing the return-gas controller  25 , the return gas is conducted to a sink, not shown, for the collection of return gas, and specifically via an opened first valve  31  to a gas or vapor separator  28 . In some embodiments, the separator  28  is a cyclonic separator. A discharge line  29  conducts away any liquid constituents separated out of the return gas. 
         [0056]    For CIP cleaning and/or disinfection of those portions of the filling system  1  that conduct the filling-material and the return gas, the pump  10  pumps a CIP medium through the product lines  11 , the first branches  13 , the second branches  15 , and ultimately to the filling heads  5 . The CIP medium returns via the return-gas line  23  to a tank or collection system via a second valve  27 . 
         [0057]    The first valve  31  also connects an outlet side of the return-gas controller  25  to the gas separator  28 . A third valve  30  bypasses the return-gas controller  25  and connects the return-gas line  23  directly to the outlet side of the return-gas controller  25 . During CIP cleaning and/or disinfection, the second and third valves  27 ,  30  open and the first valve  31  closes. 
         [0058]    With the containers  2  sealed against their respective filling heads  5 , the filling process begins with a pre-tensioning phase. During the pre-tensioning phase, the liquid valves  6  and the return-gas valves  8  all close. Then the tension gas valves  27  open, thus exposing the container interiors to tension gas under pressure. The tension gas enters the containers via the filling pipe  9 . 
         [0059]    In some practices, a flushing phase precedes the pre-tensioning phase. To execute the flushing phase, the liquid valve  6  closes, the tension-gas valves  7  open, and the return-gas valves  8  open. As a result, the tension gas enters the container&#39;s interior via the filling pipe  9 , thus forcing air from the container&#39;s interior to exit via the return-gas valves  8  and the return-gas line  23 . 
         [0060]    After pre-tensioning, pressure filling takes place. To carry out pressure filling, the tension-gas valves  7  close, the return-gas valves  8  open, and the liquid valves  6  open. The filling phase ends with closing the liquid valve  6  when the flow meter  20  determines that an appropriate amount of filling-material has entered the container  2 . 
         [0061]    During the filling, incoming filling-material forces the inert gas out of the container&#39;s interior through the return-gas line  23 . With the help of the pressure sensor  24 , the return-gas controller  25  keeps the return gas pressure constant in the return-gas line  23 . This maintains the same conditions for all containers during the pressure filling, including, in particular, conditions within the containers&#39; interiors. 
         [0062]    At the end of the filling phase, a pressure-relief valve or pressure-relief line relieves pressure within the containers  2 . 
         [0063]    During the filling phase, the flow-rate controller  18  causes the flow-rate to follow a target filling-curve FK stored in the memory of the control computer  17 . The target filling-curve FK defines a time varying flow-rate specific to the product and/or container. 
         [0064]      FIG. 3  shows an example of a target filling-curve FK. The target filling-curve FK shows filling-material flow-rate Q as a function of time at the outlet of the flow-rate controller  18 . Ideally, the flow-rate into each container  2  matches that specified in the target filling-curve FK. 
         [0065]    As shown in  FIG. 3 , the liquid valve  6  and return-gas valve  8  open at a first transition time t 1 . This starts an initial-filling interval. During this initial-filling interval, the flow-rate Q rises until it reaches a first constant flow-rate Q 1 . 
         [0066]    By a second transition time t 2 , the container has ideally been partially filled with a first volume V 2 . At this point, the flow-rate controller  18  ends the initial-filling interval and begins a quick-filling interval. In response, the flow-rate Q rises until it reaches a second constant flow-rate Q 2 . The flow-rate remains constant until a third transition time t 3 , when the flow-rate controller ends the quick-filling interval. By this time, the container  2  is ideally filled with a second volume V 4 . 
         [0067]    Following the end of the quick filling interval, at the third transition time t 3 , the flow-rate controller  18  begins an end-filling interval. To do so, the flow-rate controller  18  reduces the flow-rate until it falls to a third constant flow-rate Q 3 . In the illustrated embodiment, the third constant flow-rate Q 3  is only slightly above or below the first constant flow-rate Q 1 . 
         [0068]    The flow-rate remains at the third constant flow-rate Q 3  until the flow-rate controller  18  stops all flow. This occurs at a fourth transition time t 4 . By this time, each container  2  has been filled with the second volume V 4  of filling-material. 
         [0069]    In a typical embodiment, for a five-liter container, the first constant flow-rate Q 1  is on the order of 0.2 liters per second. As a result, 0.15-0.5 liters of filling-material will have entered the container at the end of the initial-filling interval. The second constant flow-rate Q 2  is typically on the order of 1.2 liters per second. By the end of the quick-filling interval, some 4.5-4.75 liters of filling-material will have entered each container. 
         [0070]    In practice it is not possible to maintain a perfectly constant filling-material volume flow to the filling-material heads  5 . Rather, it is necessary that each flow meter  20  measure the actual filling curve at its filling head  5  during the filling phase. This measured filling curve is then compared with the target filling-curve FK stored in the control computer  17 . Based on the comparison, the flow controller  18  takes corrective action. This corrective action takes place at the second and third transition times t 2 , t 3 . 
         [0071]    During each phase of the filling process, the containers will not fill at the same rate. Inevitably, there will be one container that is slowest to fill and another container that is quickest to fill. For convenience of exposition, the former shall be called the “last container” and the latter shall be called the “first container.” 
         [0072]    To carry out corrective control, the control computer  17  delays the end of the initial-filling interval at the second transition time t 2  until the filling-material volume in the last container has reached the first volume V 2 . The control computer  17  also delays the end of the quick-filling interval at the third transition time t 3  until the volume in the last container reaches the second volume V 4 . 
         [0073]    The corrective action takes place at the end of the quick-filling interval such that when the second volume V 4  has been conducted to the first container  2  the flow-rate controller  18  starts the end-filling interval for all the containers  2 . In the end-filling interval, the liquid valve  6  of each filling head  5  closes independently of all other liquid valves and does so when the required second volume V 4  has in fact been introduced into the container  2  concerned. 
         [0074]    The corrective action further takes place in such a way that, at the second transition time t 2 , the controller  18  briefly closes the liquid valves of those filling heads  5  that lead to containers  2  that have already reached the desired first volume V 2 . This allows the level in the last container  2  to catch up with the others. The liquid valves are then reopened once the required first volume V 2  has been introduced into the last container. As a result, the quick-filling interval begins simultaneously for all the containers. 
         [0075]    By analogy a similar corrective procedure takes place at the third transition time t 3 . 
         [0076]    In some practices of the filling method, the liquid valves  6  of all the filling heads  5  remain open at the second transition time t 2 . In that case, flow at the first constant flow-rate Q 1  continues into containers other than the last container. Only when the first volume V 2  has been introduced into the last container does a switchover to the quick-filling interval take place. At the end of the quick-filling interval, the control computer  17  prematurely closes the liquid valves  6  as needed to take into account an increased filling-material volume at the initiation of the quick-filling interval. 
         [0077]    The filling system  1  as described forms a complete component unit  32 , as shown in  FIG. 5 . The complete component unit  32  is prefabricated and mounted on the machine frame of a filling machine. 
         [0078]    The invention has been described heretofore on the basis of an exemplary embodiment. It is understood that numerous modifications and derivations are possible, without thereby leaving the inventive concept on which the invention is based.