Abstract:
The invention relates to a filling system for filling bottles or similar containers ( 2 ) with a liquid filling material, said system comprising at least one filling element, a liquid channel formed in a housing of the filling element and connected to a tank for providing the liquid filling material, and at least one outlet for dispensing the liquid filling material into the respective container attached to the filling element. Said filling system also comprises a liquid valve in the liquid channel, a gas return tube that projects past the at least one outlet on one end, for controlling the level of the filling material in the filled container, and is connected to a gas chamber, formed for example in the tank, by means of a fluid connection. The filling system also comprises an open fluid channel inside the filling element, in the region of the outlet. Said channel can be connected to a ring channel guiding a gaseous and/or vaporous fluid under pressure, preferably an inert gas under pressure, and controlled by at least one first control valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage of International Application No. PCT/EP2010/001677, filed on Mar. 17, 2010, which claims the priority of German Patent Application No. 10 2009 016 322.0, filed on Apr. 6, 2009. The contents of both applications are hereby incorporated by reference in their entirety. 
     FIELD OF INVENTION 
     The invention relates to a filling system for filling containers with a liquid filling material. 
     BACKGROUND 
     Filling system for filling containers, such as bottles, with a liquid filling material using a normal pressure filling method are known. In such filling systems, before the start of the actual filling, a container being filled is pressed with its container opening sealed tightly against the filling element. Then, with the container still sealed against the filling element, a liquid valve is opened to begin the actual filling phase. During the filling phase, gas and/or vapor is expelled from the interior of the container as the filling material flows in. This gas is typically air or an inert gas resulting from a previous rinsing, such as CO 2  gas. The expelled gas flows, via a return gas pipe that extends into the container, into a gas chamber of a tank that is common to all filling elements of the filling system. The tank is partly filled with the liquid filling material. 
     The flow of the liquid filling material into the container ends upon immersion of the lower end of the return gas pipe. The height of the return gas pipe thus determines the filling height of filling material in the container. This filling height is determined by an equilibrium between the geodetic filling material head, which is determined by the level of the filling material in the tank, and the filling material or liquid column formed in the return gas pipe and/or fluid channel internal to the filler element at the end of filling phase. The equilibrium point can therefore fluctuate. This can cause small fluctuations in fill level. 
     A known method of correcting these fluctuations is the Trinox method. In this method, the fluid channel internal to the filling element is pressurized with a pressurized gaseous and/or vaporized fluid. A suitable fluid is an inert gas under pressure, such as CO 2  gas. In response, liquid filling material from the fluid channel internal to the filling element is returned out of a head space formed above the lower end of the filling pipe in the container, and out of the return gas pipe into the tank. After executing the Trinox method, the filling level in the container lies slightly below the lower end or lower opening of the return gas pipe. Typically, the fill level lies about 2 mm to 5 mm below the lower opening of the return gas pipe. This filling system is characterized by a simple and reliable construction. 
     SUMMARY 
     An object of the invention is to improve the generic filling system by retaining its basic advantages while making possible pressurized or positive pressure filling of containers. 
     A filling system according to the invention is suitable for, among other things, positive pressure filling, and in particular for pressurized filling. The container being filled is pre-stressed with an inert gas. Before pre-stressing, the container is flushed with the inert gas. Precise setting of the fill level takes place using the Trinox method. 
     The filling system according to the invention requires merely one additional control valve per filling element, namely in the fluid connection of the return gas pipe with the gas chamber that, on pressure filling, receives the return gas expelled from the interior of the container being filled. This gas chamber is preferably the same gas chamber that is formed above the filling material level in the tank that provides the filling material. 
     Refinements, advantages and possible applications of the invention will be apparent from the following detailed description, the claims, which are part of the description, and the accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIGS. 1 to 5  each shows a filling element of a filling system of a machine of current design in simplified view and in cross section, together with a bottle in various phases of the filling process. 
     
    
    
     DETAILED DESCRIPTION 
     The filling system  1  shown in the figures fills containers, such as bottles  2 , with a liquid filling material. The filling system  1  comprises a multiplicity of identically designed filling elements  3  on the periphery of a rotor  4  that can be driven to rotate about a vertical machine axis. A container carrier  5  is allocated to each filling element  3 . In the embodiment shown, the carrier  5  is a bottle plate on which, during the filling process, a bottle  2  stands on its bottle base  2 . 1  with its bottle axis oriented in the vertical direction, i.e. along the filling element axis FA. A filling element  3  together with its container carrier  5  constitutes a filling position  6 . 
     Each filling element  3  includes a filling element housing  7 . A fluid channel  8  formed in this housing  7  connects, via a product line  9 , with a tank  10  common to all filling elements  3  of the filling system  1  or filling machine. The tank  10  is provided on the rotor  4 . On the underside of the filling element  3 , the tank  10  forms an outlet  11  to discharge the liquid filling material to the bottle  2  at the filling position  6 . 
     During the filling process, the tank  10  is partly filled with liquid filling material to a controlled level. The tank  10  is thus divided into a fluid chamber  10 . 1  filled by the filling material and a gas chamber  10 . 2  that lies above the fluid chamber  10 . 1 . During pressure filling, the pressure of an inert gas, for example CO 2  gas, controls the pressure within the gas chamber  10 . 2 . 
     A control device  12  controls a liquid valve  13  in the fluid channel  8 . The liquid valve  13  comprises a valve body  13 . 1  formed by a tube  14 . The tube  14 , which is open at both ends and which is coaxial with a vertical filling element axis FA, protrudes through the outlet  11  over the underside of the filling element  3  or a ring seal  15 . 1  provided in a centering sleeve  15 . An upper end of the tube  14  opens into a chamber  16  that is part of a system of gas ways  17  formed in the filling element housing  7 . Through the gas ways  17 , the chamber  16 , and hence also a fluid channel formed inside the tube  14  internal to the filling element, can also be connected to a ring channel  19  by controlling a first control valve  18 . Details of making the connection are described below. 
     The ring channel  19  is common to all filling elements  3  on the rotor  4 . During the filling process, the ring channel  19  carries an inert gas at a pressure that is greater than the pressure in the gas chamber  10 . 2 . A suitable inert gas is CO 2  gas under pressure. 
     Each filling element  3  comprises a return gas pipe  20  for determining a filling height. The return gas pipe  20  is coaxial with the filling element FA. From above, the return gas pipe  20  passes, sealed by the filling element housing  7 , through the chamber  16  and continues through the tube  14 . Its lower end, or the opening therein, protrudes from the lower end of the tube  14 . The upper end of the return gas pipe  20  connects, via a second control valve  21  and a flexible line  22 , to the gas chamber  10 . 2  of within tank  10 . 
     When the Trinox method is used, the return gas pipe  20  determines the fill level in the bottle at the end of the filling process. To adjust the fill height, the return gas pipe  20  of each filling element  3  can be adjusted to move up and down along the filling element axis FA, as indicated by double arrow A. A central adjustment device can control this adjustment. 
     A special feature of the filling system  1  is the second control valve  21 , which is disposed in the connection between the return gas pipe  20  and the gas chamber  10 . 2 . With the filling system, with the filling elements  3 , and/or with the corresponding filling machine, the presence of this second control valve  21  makes various filling methods possible. For example, pressure or positive pressure filling becomes possible, as described in connection with  FIGS. 1 to 5 . In the description of the illustrated method, the liquid valve  13  and the first and second control valves  18 ,  21  are each in their closed position as long as the open position is not expressly specified. 
     The first step is to flush the bottle  2  with inert gas, as shown in  FIG. 1 . After delivering the bottle  2  to a filling position  6 , the bottle is raised towards the filling element  3 , but not all the way to the filling element  3 . This leaves a gap between the bottle opening  2 . 2  and the seal  15 . 1 . Opening the second control valve  21  introduces inert gas from the gas chamber  10 . 2  via the return gas pipe  20  to flush the bottle  2 . This causes air in the bottle  2  to dissipate via the gap between the bottle opening  2 . 2  and the seal  15 . 1 . As the air dissipates, progressively greater amounts of the inert gas also dissipate through this gap. 
     In another embodiment, dissipation of air and inert gas during flushing can also take place via a gas channel formed in the filling element housing  7 . In this embodiment, the bottle  2  lies pressed with its bottle opening  2 . 2  sealed against the filling element  3  or against the seal  15 . 1  even during the abovementioned flushing operation. 
       FIG. 2  shows the next step, namely pre-stressing the bottle  2 . With the bottle  2  sealed against the filling element  3 , opening the second control valve  21  exposes the interior of the bottle  2  to a pressurized inert gas from the gas chamber  10 . 2 . This pre-stresses the bottle  2 . 
       FIG. 3  shows the next step, namely filling the bottle  2 . With the bottle  2  still sealed against the filling element  3 , and with the second control valve  21  open, the liquid valve  13  is opened. This allows liquid filling material to flow into the bottle  2  via the outlet  11 . The inert gas expelled by the liquid filling material from the interior of the bottle, at least in the end phase of filling, is expelled solely via the return gas pipe  20  and the opened second control valve  21  into the gas chamber  10 . 2 . 
     The flow of the liquid filling material into the bottle  2  automatically ends while the liquid valve  13  is still open. In particular, the flow ends upon immersion of the opening at the lower end of the return gas pipe  20  into the filling material in the bottle  2 . This filling material will have risen both in the return gas pipe  20  and in the tube  14  to a height such that equilibrium exists between the filling material column in the return gas pipe  20  or in the tube  14  and the geodetic head of the filling material in the tank  10 . 
     The next steps, which are shown in  FIG. 4 , are to adjust the precise filling height, and to return the filling material to the tank  10 . The filling material to be returned comes from the tube  14 , the return gas pipe  20 , and the headspace  2 . 3  of the bottle  2  above the lower end of the return gas pipe  20 . 
     With the liquid valve  13  closed and the second control valve  21  open, the first control valve  18  is opened. As a result, pressurized inert gas from the Trinox or ring channel  19  enters. This forces the filling material to be returned into the tank  10  until the level of the liquid filling material within the bottle is approximately 2 to 5 mm below the lower end of the return gas pipe  20 . The chamber  16 , the tube  14 , and the fluid channel provided internal to the filling element are all connected to the ring channel  19  via the open first control valve  18  and a choke  17 . 1  provided in the gas ways  17 . 
     After the precise adjustment of the filling level and drainage of the return gas pipe  20 , the bottle is lowered and relieved, as shown in  FIG. 5 . This requires closing the first and second control valves  18 ,  21 , closing the liquid valve  13 , and controlled lowering of the container carrier  5 . 
     With the filling system  1  as described herein, it is possible to carry out positive pressure filling of the bottle  2  described above. However, it is also possible to carry out normal pressure filling, and, in particular, normal pressure filling with adjustment of the precise fill level using the Trinox method. 
     To carry out normal pressure filling, the gas chamber  10 . 2  of the partly filled tank  10  is filled with inert gas at atmospheric pressure. The filling of the bottle  2  then takes place with the second control valve  21  permanently open. The bottle  2  is first pressed against the filling element  3  with a seal. To initiate the filling phase, the liquid valve  13  is opened. After closing the liquid valve  13 , the first control valve  18  is opened again to adjust the precise fill level with the Trinox method. 
     Due to the second control valve  21 , the filling system  1  is suitable for carrying out positive pressure filling as described above, and doing so without great complexity. The filling system thus offers the advantage of permitting both normal pressure filling and positive pressure filling. 
     Despite the possibility of adjusting the fill level for all filling elements together, for example automatically, and despite the integral Trinox filling level correction or adjustment for precise filling levels, the filling system requires only two control valves  18 ,  21  per filling element  3 . These valves  18 ,  21  can be controlled pneumatically. 
     In addition to the tank  10 , in the simplest case only one further gas channel is required for all filling elements  3 , namely the ring channel  19  on the rotor. The ring channel  19  can also be used for CIP cleaning of the filling machine. To carry out CIP cleaning, a non-return valve  17 . 2  is provided in the gas way  17  parallel to choke  17 . 1 . 
     The present invention also extends to a method in which the container or the bottle is withdrawn from the filling element without the prior relief phase i.e. under positive pressure. 
     Withdrawal under positive pressure is possible because the Trinox method leaves a gap between the filling material level and the lower end of the return gas pipe  20  and because the second control valve  21  can be used to interrupt the connection to the gas chamber  10 . 2  via the flexible line  22 . The small distance between the lower end of the return gas pipe  20  and the filling material level constitutes an open gas connection between the headspace of the bottle  2  and the return gas pipe  20 . 
     Before lowering the bottle  2 , the second control valve  21  is closed. This prevents further flow of pressurized gas from the tank  10 . Upon withdrawal of the bottle  2  from the filling valve seal, the gas volume existing inside the return gas pipe  20  automatically expands. This results in formation of a gas or pressure pulse that is directed towards the end of the return gas pipe  20 . 
     Because the lower end of the return gas pipe  20  is spaced above the filling material level, the gas or pressure pulse that emerges from the return gas pipe  20  and that is directed onto the filling material only has a restricted minimal effect. This is because substantial expansion or diffusion losses are associated with its emergence from the return gas pipe  20 . 
     Finally the procedure described above allows a clear reduction in undesirable foaming of the filling material. At the same time, the otherwise normal pressure release valve relied upon in the prior art can be omitted.