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.

Description

FIELD OF INVENTION

The present invention relates to filling containers with liquid filling material, and in particular, to pressure filling.

BACKGROUND

In a known filling process, a return gas tube of a filling element extends into a container and conveys away gas displaced from the container as liquid filling material enters the container. A pressure sensor connected to either the container's interior or a return gas line measures the pressure over the entire filling process and sends a corresponding signal to an evaluating device. The evaluating device records the progression of pressure over time for the entire filling process and compares the result with desired values. From this comparison, a controller of the filling device detects whether the filling process is proceeding correctly. The controller may also bring about a change in the process cycle as a result of the pressure progression determined by the evaluating device.

SUMMARY

An object of the invention is to provide a method for the pressure-filling of containers in a way that makes it simpler to control the filling process.

According to the invention, the filling element of the filling device is controlled as a function of an output signal from the evaluating device. The evaluating device monitors the pressure progression, and in particular, the occurrence of a pressure peak that occurs when the filling-material level in the container reaches the return gas tube. When this pressure peak is detected, a closing signal is sent to the filling element. In response, the filling element immediately stops delivering filling material into the container. The closing signal can be a switching signal of the evaluating device that is either transmitted to the controller of the filling device that controls the filling element, or is sent directly to the filling element. If the evaluating device is part of the controller of the filling device, then the closing signal is generated in the controller itself. According to the invention, the closing of the filling element, which is usually realized by a filling valve, is made directly dependent on the signal of the pressure sensor. As a result, the filling element or filling valve closes immediately upon detection of the pressure peak in question. A seal seat in the filling valve is usually closed for this purpose.

In the method described herein, the pressure progression is not used to modify the entire filling process. Instead, the detection of a certain pressure peak in the pressure progression is directly used to derive the closing signal for the filling valve.

The invention is thus based in part on the recognition that a small pressure peak always occurs in the pressure progression when the filling-material level in the container reaches the return gas tube. In addition, the invention is based in part on the realization that this pressure peak can be used as a trigger for closing the filling element. The invention therefore facilitates a very simple control of the filling process, above all, towards the end of the filling process. The invention obviates the need for an additional fill-level sensor. This represents a significant advantage. Elimination of the fill-level sensor simplifies or eliminates considerable electrical cabling. Additionally, the considerable cost of the fill-level sensor is saved.

The terms “filling element” and “filling valve” are used synonymously hereinafter.

As already described above, the evaluating device can be a separate unit or part of a controller of the filling device. It is also possible to realize the evaluating device and its components as software implemented in a controller of the filling device. Individual components of the invention can be provided singly or in multiples. In addition it is also possible to use the pressure progression to control the entire filling process.

In order for the evaluating device to record the pressure peak from the pressure progression, the first chronological derivation of successive pressure values is used for the detection of the pressure peak. This first chronological derivation is then compared with a reference value. When the reference value is reached, it is assumed that the pressure peak, which indicates that the filling-material level has reached the return gas tube, is present, whereupon the closing signal for the filling element or a switching signal is immediately output, either directly to the filling element or to the controller of the filling device, for closing the filling element.

According to the invention, the absolute pressure at the time when the pressure peak is detected is also taken into account. In this way, it is possible to prevent any other pressure peak in the filling process from being used other than the one at which the rising filling-material level reaches and/or closes off the lower end of the return gas tube. By taking into account the absolute pressure, it can therefore be ensured that the pressure peak is present at a pressure level that should be present when the desired pressure peak is present, which occurs at the end of the filling process when the return gas tube is closed off by the rising filling-material level.

Preferably, the pressure measurements over a period of 0.1-3 seconds are used for the detection of the pressure peak. The successive pressure measurements over a period of time such as this are well suited to determining pressure plateaus and pressure peaks in a pressure progression.

Preferably, the difference between the last 5 to 50 pressure measurements and an average of pressure measurements over the last 1 to 3 seconds can be determined for the detection of the pressure peak. This pressure differential is compared, for example, with a reference value, with the pressure peak in question assumed to be present when that reference value is reached or exceeded.

The pressure peak that occurs when the rising filling-material level reaches the end of the return gas tube has not previously been used for process control in the filling process. The present invention does this. In doing so, it simplifies process control, especially at the end of the filling process.

In addition the pressure differential between the foot and vertex of the pressure peak can also be taken into account for the detection of the pressure peak. This ensures consideration of only those pressure peaks having a certain minimum amplitude.

When filling containers that have an upwardly narrowing inner cross-sectional area, a first pressure peak in the pressure progression does not usually occur until the filling-material level rising in the container reaches the region in which the cross-sectional area begins to taper. A braked filling, i.e., a slower filling of the container, begins when this tapering level is reached. Provision can now be made for only the pressure peaks that occur after the start of the braked filling to be taken into consideration. In this way, all pressure peaks previously occurring in the filling process are disregarded. This increases the certainty of detecting the correct pressure peak, namely the one that corresponds to the filling-material level in the container having reached the return gas tube.

When containers are pressure-filled, the container is preferably pre-purged with an inert gas, if applicable after multiple cleaning rinses with air, oxygen or inert gas. The filling process can be accelerated in this way.

The inventive method allows rapid and reliable control of the filling process. This is especially useful for filling carbonated filling-material such as lemonades, beer, cola or the like.

In one aspects, the invention features a device for the pressure-filling of containers. Such a device has at least one filling element, and preferably a plurality of filling elements, against each of which a container lies tightly by its container opening at least during part of the filling process and by which at least one process pressure is applied to the interior of the container in at least one process step during the filling process. The pressure is applied, as a rule, but not necessarily, with an inert gas. The filling element is connected to at least one pressure sensor that, during the filling process, senses the pressure in the interior of the container, which is connected to the filling element, and that provides an electrical signal, which corresponds to the pressure, to an evaluating device. During the filling process, a return gas tube of the filling element extends into the container and conveys away the gas displaced from the container as the filling material fills the container.

In some embodiments, the evaluating device is functionally connected to the filling element and has a detection device for recording a pressure peak at the end of a filling process. The pressure peak indicates that the filling-material level in the container has reached the return gas tube.

The detection apparatus can be implemented in the evaluating device, e.g., by way of software. It can also be provided as a discrete module inside or outside the evaluating device. In the same way, the evaluating device can be an independent module. Or it can be integrated into a controller of the filling device. The detection apparatus has a calculation unit that, from the electrical signal of the pressure sensor, calculates the presence or absence of the pressure peak in question. This pressure peak indicates that the filling-material level has reached the return gas tube.

Reference is made to the statements in the description of the inventive method for the basic considerations and advantages of the inventive device.

Preferably, a series of successive pressures measured over a certain period of time, e.g. the last 50 to 100,000 measurements, is used for the calculation of the pressure peak, since this makes it possible to distinguish plateaus from pressure peaks in the pressure progression. The additional consideration of the absolute pressure value makes it possible to associate plateaus and pressure peaks with certain stages of the filling process. The pressure peak that occurs when the return gas tube is closed by the rising filling pressure level takes place at the end of the filling process. The evaluating device is therefore preferably configured so as to be able to associate the presence of a detected pressure peak from the pressure progression with the end of the filling process such that the association of the pressure peak with the point in time in the process when the return gas tube has been reached by the rising filling-material level is unambiguous.

A time-based controller, which ensures that only pressure peaks occurring within a certain time window within the pressure progression of the filling process are captured, can also preferably be used for the detection of the pressure peak.

The pressure sensor is preferably arranged on a gas channel that is configured in the filling element and that is connected to the interior of the container positioned at the filling element. This gas channel is preferably the return gas channel located in the filling element and connected to the return gas tube. The pressure peak that occurs when the return gas channel is closed can be detected most clearly in this way.

The term “detect” is used here to mean a recognition process that is based on the measurements by the pressure sensor as well as on calculation algorithms of the evaluating device that enable these measurements to be associated with certain events of the filling process.

In some embodiments, the filling device comprises a plurality of filling elements, with preferably one common evaluating device being provided for all filling elements.

In other embodiments, the filling element is configured as a filling valve. When the filling valve closes, at least one seal seat of the filling valve closes.

In some embodiments, the filling device is a rotary filling device comprising a plurality of container holders and associated filling elements around its periphery. Rotary filling devices of this type are currently in general use and reliable in operation as well as being comparatively space-saving.

In other devices, the filling device is an in-line filling device, such as a linear container-filling machine, in which the filling elements are arranged in a line relative to one another and in which the containers move in a straight line through the container-filling machine. Other embodiments include those in which a filling device has only one filling element.

Both the detection apparatus of the evaluating device and the evaluating device itself can be software-implemented in a controller of the filling device. In many embodiments, the filling device's controller is based on a processor.

The embodiments of the invention described above can be combined with one another in any desired manner provided this is not technically inconsistent.

BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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).

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.

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

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.

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.