PRESSURE-FILLING OF CONTAINERS

Abstract

A method of pressure-filling a container includes placing its opening tightly against a filling element, extending a return gas tube into the container, causing and measuring a progression of pressures in the container's interior, thereby generating a measured progression of pressures, generating a signal indicative of the measured progression of pressures, recording it, monitoring it for information indicative of a pressure peak, identifying such information, comparing a measured value of the pressure peak with a reference value, measuring an absolute pressure at a point in time at which the pressure peak is measured, based at least in part this measurement, determining that the pressure peak is caused by the filling-material level having reached the return gas tube, and upon making the determination, transmitting closing the filling element.

Claims

1-7. (canceled)

8. A method of pressure-filling a container, said method comprising placing said container's opening tightly against a filling element, extending a return gas tube into said container, causing a progression of pressures in said container's interior, measuring said progression of pressures in said container's interior, thereby generating a measured progression of pressures, generating an electrical signal indicative of said measured progression of pressures, recording said electrical signal, thereby generating a recorded electrical signal, monitoring said recorded electrical signal for information indicative of a pressure peak, identifying information indicative of a pressure peak, comparing a measured value of said pressure peak with a reference value, measuring an absolute pressure at a point in time at which said pressure peak is measured, based at least in part on said absolute pressure, determining that said pressure peak is caused by a filling-material level having reached said return gas tube, and upon making said determination, transmitting a closing signal to close said filling element.

9. The method of claim 8, wherein monitoring said recorded electrical signal for information indicative of a pressure peak comprises monitoring said recorded electrical signal for sufficient time to provide pressure measurements over a period of between one-tenth of a second and three seconds, said pressure measurements to be used for detection of said pressure peak.

10. The method of claim 8, wherein identifying information indicative of a pressure peak comprises, for each pressure measurement in a set of pressure measurements, determining a difference between said pressure measurement and an average of pressure measurements and comparing said difference with a reference value, wherein said set of pressure measurements comprises a set of between five and fifty preceding pressure measurements and said average of pressure measurements is an average of pressure measurements from a preceding one to three seconds.

11. The method of claim 8, wherein identifying information indicative of a pressure peak comprises identifying a pressure differential between a foot of said pressure peak and a vertex of said pressure peak, and using said pressure differential as a basis for determining that said pressure peak is caused by said filling-material level having reached said return gas tube.

12. The method of claim 8, further comprising selecting said container to be a container having a cross-section that decreases with increasing distance from a base of said container, and causing filling of said container to transition from a rapid filling process to a slow filling process, said transition corresponding to a point on said progression of pressures, wherein determining that said pressure peak is caused by said filling-material level having reached said return gas tube comprises doing so based only on pressures in said pressure progression that are after said point.

13. The method of claim 8, wherein determining that said pressure peak is caused by said filling-material level having reached said return gas tube comprises doing so at least in part on the basis of a time at which said candidate pressure peak occurs in said measured progression of pressures.

14. The method of claim 8, wherein causing a progression of pressures in said container's interior comprises pre-charging said container with an inert gas prior to entry of liquid-filling material into said container.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention is described below by way of example by reference to the schematic drawing in which:

[0034] FIG. 1 shows a partial-section view of part of a filling device with a filling valve and a container;

[0035] FIG. 2 shows a plot of a conventional pressure progression as recorded in the evaluating device in FIG. 1, and

[0036] FIG. 3 shows a schematic diagram of a pressure progression during the filling of a container that has an upwardly narrowing container cross-section.

DETAILED DESCRIPTION

[0037] FIG. 1 shows a filling element in the form of a filling valve 10 of a rotary filling device 8 in detail, preferably as a filling valve without a filling tube. A housing 12 that houses the filling valve 10 defines a liquid channel 14 in which is arranged a seal seat 16. An actuator opens the seal seat 16 at the start of the filling process and closes it at the end of the filling process.

[0038] FIG. 1 shows the seal seat 16 in its open position. The filling valve 10 is arranged on an outer part of a rotor 11 of the rotary filling device 8. However the filling valve 10 may also be arranged on an in-line filling device or the like.

[0039] The liquid channel 14 connects to an annular tank 18 arranged coaxially on the rotor 11. The annular tank 18 defines a filling material chamber 20 and a gas space 22 above the filling material chamber 20. An inert gas, such as carbon dioxide gas, fills the gas space 22.

[0040] A filling material line 24 supplies the filling material chamber 20 with the liquid filling material in such a way that the level N of filling material in the annular tank 18 is regulated to a specified or pre-selected value. A pre-tensioning gas line 26 supplies the gas space 22 with the pressurized inert gas at constant or essentially constant pressure.

[0041] A number of devices are provided on the rotor 11 and shared by all the filling valves 10. These devices include a pre-tensioning gas ring channel, a supply line 30 that connects the pre-tensioning gas ring channel 28 to the gas space 22, a first return gas ring channel 32 for preliminary pressure relief, and in which a pressure equal to the relief pressure is maintained, a second return gas ring channel 34 connected to the atmosphere for further pressure relief, and a vacuum ring channel 36 connected to a vacuum source.

[0042] Each filling valve 10 has a return gas tube 38. When a bottle 40 is located at the filling valve 10, the a lower open end of the return gas tube 38 opens out into the interior of the bottle 40.

[0043] In addition to defining the liquid channel 14, the housing 12 also defines gas paths, among which is a gas channel 42. An upper open end of the return gas tube 38 opens out into this gas channel 42.

[0044] An individually controllable control valve 44 at each filling valve 10 controls the gas paths. Depending on the particular treatment or process step that a bottle sealed against the filling element 10 is engaged in, the control valve 44 connects that bottle's interior to one of the pre-tensioning gas ring channel 28, the first return gas ring channel 32 the second return gas ring channel 34, or the vacuum ring channel 36. This results in a pressure progression, an example of which is shown in FIG. 2 for the case in which the filling valve 10 is working correctly.

[0045] The gas channel 42 connects to a pressure sensor 46. Through the return gas tube 38, the pressure sensor 46 constantly records the progression of pressure present inside the bottle 40 provided at the filling valve 10. The pressure sensor 46 delivers the corresponding measurement to an evaluating device 48.

[0046] The evaluation device 48 is provided in common for all the filling valves 10 or their pressure sensors 46. Preferably, the evaluation device 48 includes a computer. In some embodiments, the evaluating device 48 is part of a controller. In others, the evaluating device 48 is a discrete function module in addition to the controller.

[0047] With the pressure sensors 46 and the evaluating device 48 it is possible on the one hand to monitor and/or diagnose individual filling valves 10 with the machine running, i.e. any malfunction of individual filling valves is detected early to allow counter-measures to be taken as required. However, an automatic, filling material-specific control of the filling process is also possible with the pressure sensors 25 and the common evaluating device 48.

[0048] FIG. 2 shows a graph of a pressure progression 50 which measured by the pressure sensor 46 at the filling valve 10 and recorded by the evaluating device 48 during the filling of a container that has a constant cross-section, such as a can. The ordinate and abscissa represent pressure and time respectively.

[0049] The pressure progression 50 shows the pressure at the start of the filling process (step 52), during the container's pre-evacuation (step 54) while purging inert gas from the container (step 56), while partially pre-charging the container to a pressure P2 (section 58), while pre-charging the container to a charging or filling pressure P1 (step 60), and during a rapid filling process (step 62).

[0050] The pressure progression 50 also shows the pressure peak 64, at which point the filling-material level in container reaches the return gas tube 38. Upon learning about the pressure peak 64, the evaluating device 48 closes the seal seat 16.

[0051] Following closure of the seal seat 16, the progression 50 continues with a preliminary pressure-relieving step, for example, down to pressure P2 (step 66) and a residual pressure relieving step down to atmospheric pressure (step 68). At this point, the pressure progression 50 arrives at the end of the filling process (step 70).

[0052] FIG. 3 shows the pressure progression during the filling of a container having a cross-section that varies. The particular example is for a beer bottle, which has an essentially constant cross section until one approaches the bottle's neck. Process steps that are the same as those in FIG. 2 are provided here with the same reference numbers.

[0053] Unlike the pressure progression shown in FIG. 2, the pressure progression shown in FIG. 3 has first and second pressure peaks 63, 64.

[0054] The first pressure peak 63 occurs when the filling-material level reaches the beginning of the bottle's neck. Within the pressure progression 50, this occurs in the region of pressure plateau P1. Slow filling 65, otherwise known as braked filling, begins with this first pressure peak 63. It is important that the evaluating device 48 detect the second pressure peak 64 and not the first pressure peak 63 as being the signal that the filling-material level in the bottle has reached the return gas tube. Upon detecting the second pressure peak 64, it closes the filing valve's seal seat 16. In some embodiments, the start of slow filling enables detection of the second pressure peak 64.