METHOD FOR FILLING PLASTIC BOTTLES PRODUCED BY STRETCH-BLOW-MOLDING

Abstract

A method that comprises receiving a plastic container that has been formed by stretch blow molding and immediately after having received the container, while the container is still hot from having been formed, filling the container with carbonated liquid. Filling the container with the carbonated liquid comprises setting an internal pressure of the container to be a first pressure and causing the internal pressure to change from the first pressure as a function of a variable. The variable is either an extent to which the container is filled or a container temperature.

Claims

1-17. (canceled)

18. A method comprising receiving a plastic container that has been formed by stretch blow molding and, immediately after having received said container, while said container is still hot from having been formed, filling said container with carbonated liquid, wherein filling said container with said carbonated liquid comprises setting an internal pressure of said container to be a first pressure and causing said internal pressure to change from said first pressure as a function of a variable, wherein said variable is selected from the group consisting of an extent to which said container has been filled and a container temperature.

19. The method of claim 18, further comprising restraining carbon dioxide that leaves said carbonated liquid as a result of frothing from leaving said container.

20. The method of claim 18, further comprising measuring a temperature of said container, wherein causing said internal pressure to change comprises causing said internal pressure to change as a function of said measured temperature.

21. The method of claim 18, further comprising measuring a quantity of carbonated liquid that has been introduced into said container, wherein causing said internal pressure to change comprises causing said internal pressure to change as a function of said measured quantity.

22. The method of claim 18, further comprising measuring a filling level in said container, wherein causing said internal pressure to change comprises causing said internal pressure to change as a function of said measured filling level.

23. The method of claim 18, further wherein causing said internal pressure to change comprises causing said internal pressure to change as a function of filling time.

24. The method of claim 18, further comprising selecting said first pressure to be no greater than 2 bar.

25. The method of claim 18, further comprising selecting said first pressure to be no greater than halfway between said ambient pressure and twice said ambient pressure.

26. method of claim 18, further comprising selecting said first pressure to be ambient pressure.

27. The method of claim 18 further comprising setting a reference pressure, wherein said reference pressure is an internal pressure that is to exist in said container upon having completed filling of said container, wherein causing said internal pressure to change comprises keeping a return-gas channel closed until a predetermined filling level has been reached and, after said predetermined filling level has been reached, increasing said internal pressure to said reference pressure.

28. The method of claim 27, further comprising opening said return-gas channel after said internal pressure has reached said reference pressure.

29. The method of claim 18, wherein causing said internal pressure to change comprises causing said internal pressure to change in stages.

30. The method of claim 18, wherein causing said internal pressure to change comprises alternating between changing pressure and filling said container.

31. The method of claim 18, further comprising setting a reference pressure, wherein said reference pressure corresponds to an internal pressure that is to be present in said container upon having filled said container, wherein said reference pressure is between 5 bar and 7 bar.

32. The method of claim 18, wherein filling said container comprises causing said container to be filled at said first pressure during a first interval, wherein said first interval is an interval during which an extent to which said container has been filled is between 5% and 20%.

33. The method of claim 18, wherein filling said container comprises causing said container to be filled at said first pressure during a first interval, wherein said first interval is an interval during which an extent said container has been filled is between 2% and 30%.

34. The method of claim 18, wherein filling said container comprises causing said container to be filled at said first pressure during a first interval and causing said container to be filled at a second pressure during a second interval, wherein said first interval is an interval during which an extent to which said container has been filled is below a first value and wherein said second interval is an interval during which an extent to which said container has been filled is above said first value.

35. The method of claim 18, wherein filling said container comprises using hydrostatic pressure of said carbonated liquid to fill said container.

36. An apparatus configured for receiving a plastic container that has been formed by stretch blow molding, wherein said apparatus is configured to, immediately after having received said container, while said container is still hot from having been formed, carry out filling of said container with carbonated liquid, wherein filling of said container comprises setting an internal pressure of said container to be a first pressure and causing said internal pressure to rise as a function of a changing variable, wherein said changing variable is selected from the group consisting of an extent to which said container has been filled and an extent to which a container temperature has been decreased, said apparatus comprising a stretch blow molding machine and a filling machine downstream of said stretch blow molding machine and next to said filling machine, wherein no cooling segment separates said stretch blow molding machine from said filling machine, wherein, as a result, plastic containers proceed directly from said stretch molding machine to said filling machine.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0051] FIG. 1 shows a device for producing and filling PET bottles;

[0052] FIG. 2 shows a detail from the filling machine from FIG. 1 for the gas-tight controlling of the pressure in the bottle interior during the filling;

[0053] FIG. 3 shows various possibilities for controlling the pressure during the filling of the bottle as a function of the extent to which the bottle has been filled, and

[0054] FIG. 4 shows three methods for controlling the pressure in the bottle as a function of elapsed time since the start of filling.

DETAILED DESCRIPTION

[0055] FIG. 1 shows a device 10 for producing and filling PET bottles.

[0056] The device 10 comprises a stretch blow-molding machine 12 and a filling machine 14 arranged directly thereafter. The blow-molding machine 12 connects directly to the filling machine 14 with no cooling segment arranged between them.

[0057] The blow-molding machine 12 receives bottle preforms 15 and blows them, while they are still hot, into bottles 25, such as bottles. In an alternative embodiment, the blow-molding machine 12 begins with PET pellets instead of preforms. Once the bottles 25 have been formed, the blow-molding machine 12 transfers them to the filling machine 14 directly downstream. The filling machine 14 then outputs filled bottles 17.

[0058] The filling machine 14 includes a beverage reservoir 16 from which it draws on a supply of beverage that is to be bottled. Examples of a beverage reservoir 16 include a tank and a delivery-line.

[0059] The filling machine 14 also includes a pressure-control device 18 that connects to a compressed-gas source 20. This permits the pressure within the bottle 25 to be controlled during filling thereof.

[0060] FIG. 2 shows the filling machine 14 with a sleeve 26 forming a gas-tight connection between the filling-machine's outlet 22 and an opening 24 of a bottle 25. In the illustrated embodiment, the filling valve 28 has been opened. As a result, a jet 30 of beverage flows past the filling valve 28 and into the bottle's interior 32. This displaces gas, referred to herein as the return gas. The return gas escapes through a return-gas channel 34 that connects the bottle's interior 32 to the beverage reservoir 16.

[0061] In some cases, it is also necessary to introduce compressed gas into the bottle 25. For this purpose, a compressed-gas line 36 connects the bottle's interior 32 to the compressed-gas source 20.

[0062] The optimal pressure in a bottle 25 during the filling process is generally not constant. It varies as a function of the extent to which the bottle 25 is filled. By regulating or controlling both the return gas channel 34 and the compressed gas line 36 during the filling process, it is possible to individually control the pressure in each bottle 25 to take into account different filling behaviors associated with different beverages, i.e. in particular of beverages with different carbon-dioxide concentrations.

[0063] FIGS. 3 and 4 show trajectories of internal pressure as a function of different independent variables. In both figures, the internal pressure is along the vertical axis and the independent variable is along the horizontal axis. In FIG. 3, the independent variable is the extent to which the bottle is filled, expressed in percent. In FIG. 4, the independent variable is the elapsed time from the onset of the filling procedure. In all the examples from FIGS. 3 and 4, hydrostatic pressure provides the filling pressure of the beverage.

[0064] According to an exemplary filling curve a in FIG. 3, filling begins with opening the filling valve 28 and leaving the return-gas channel 34 open. As a result, when the jet 30 runs into the bottle 25, the displaced gas and any carbon dioxide that comes out of solution can escape through the return-gas channel 34. This configuration thus holds the pressure in the bottle's interior 32 at an initial pressure p1 of 1 bar, which is also the ambient pressure.

[0065] As soon as 10% of the bottle 25 has been filled, the return-gas channel 34 closes and the compressed-gas line 36 opens. This quickly raises pressure in the bottle 25 to a reference pressure p2, where it remains until the bottle 25 has been completely filled. In the illustrated example, the reference pressure p2 is 6.5 bar.

[0066] In a second filling curve b, the filling valve 28 opens such that the jet 30 runs into the bottle 25. However, instead of leaving the return-gas channel 34 open, it remains closed. This means that displaced gas cannot escape through the return-gas channel 34. As a result, the pressure rises. By the time the bottle 25 has been filled to 10% or 20%, the internal pressure will have reached about 1.4 bar. At that point, the compressed-gas line 36 opens. This sharply raises pressure up to 6.5 bar. Since gas does not move infinitely fast, the pressure rise is not instantaneous. For example, using typical filling equipment with a 500-milliliter bottle 25, this pressure rise can take about 500 milliseconds.

[0067] As shown in FIG. 2, a regulating valve 37 opens the compressed-gas line 36. Such a regulating valve 37 permits the temporal course of the pressure rise to be adjusted. For example, by partially closing the regulating valve 37, it is possible to slow the rise to the regulating pressure by 1 to 3 seconds.

[0068] In a third filling curve c, the filling process again begins at ambient pressure but with the return-gas channel 34 closed. The regulating valve 37 opens to admit compressed gas and does so in a way that causes the internal pressure to reach the reference pressure when the bottle 25 has been filled to 30%.

[0069] In a fourth filling curve d, the filling process again begins at ambient pressure but with the return-gas channel 34 closed. The regulating valve 37 opens to admit compressed gas and does so in a way that causes the internal pressure to reach the reference pressure when the bottle 25 has been filled to 100%.

[0070] An advantage of the fourth filling curve d is that no channels need to be opened or closed during the actual filling process. This method therefore avoids introducing any pressure transients. As a result, the pressure rises continuously.

[0071] According to a fifth filling curve e, filling begins with opening the filling valve 28 and leaving the return-gas channel 34. This holds the bottle's internal pressure at 1 bar. As a result, when the beverage jet 30 runs into the bottle 25, the displaced gas and any carbon dioxide that comes out of solution can escape. This maintains a constant 1 bar pressure.

[0072] Upon 10% of the bottle 25 having been filled, the return-gas channel 34 closes and the compressed-gas line 36 opens. This quickly raises pressure in the bottle 25 to an intermediate pressure of 4 bar.

The regulating valve 37 then opens to admit compressed gas. It does so in a way that causes the internal pressure to linearly increase until it reaches the reference pressure. This occurs when the bottle 25 has been filled to 100%.

[0073] In the examples shown in FIG. 4, bottle filling takes seven seconds. The time required to fill depends on the size of the bottle 25 and how fast beverage enters the bottle. For most practical applications, the time required to fill the bottle 25 is between three and twenty seconds.

[0074] A method that executes the sixth filling curve f begins with opening both the filling valve 28 and the return-gas channel 34 for one second to maintain the bottle's interior at ambient pressure. The method continues with opening the regulating valve 37, thus connecting the bottle's interior 32 to the compressed-gas source 20 via the compressed-gas line 36. This causes the internal pressure to rapidly rise to the reference pressure. In the illustrated example, the internal pressure rises to a reference pressure of 6.5 bar within about 0.2-0.5 seconds.

[0075] A method that executes the seventh filling curve g begins with opening both the filling valve 28 but keeping the return-gas channel 34 closed during the first second. As a result, the internal pressure rises during the first second from gas displaced by incoming beverage and by carbon dioxide that comes out of solution. The method continues with opening the regulating valve 37, thus connecting the bottle's interior 32 to the compressed-gas source 20 via the compressed-gas line 36. This causes the internal pressure to rapidly rise to the reference pressure. In the illustrated example, the internal pressure rises to a reference pressure of 6.5 bar within about 0.2-0.5 seconds.

[0076] A method that executes the eighth filling curve h proceeds by linearly increasing internal pressure over the course of the entire filling time, which in the illustrated embodiment lasts for seven seconds.