EP0528216A1 - Method and apparatus for filling containers - Google Patents

Abstract

The invention relates to a method for filling a container (2) with a liquid and an apparatus for implementing the method, the liquid being fed to the container via a liquid pipe, at least one probe (15) being used to check whether a predetermined filling level has been reached in the container and the supply of liquid being stopped once one of the probes has been actuated. By means of the method according to the invention and the associated apparatus, the accuracy of the final filling level is to be improved in a simple fashion. To this end, liquid is once again fed after a predetermined delay until one of the probes is once again actuated, when the supply of liquid is once again stopped. <IMAGE>

Description

The invention relates to a method for filling a container with the features of the preamble of claim 1 and a device for performing the method with the features of the preamble of claim 7.

Such a method and such a device are known from DE-OS 32 45 731. There the liquid is filled into a container under counter pressure. To prevent the liquid from reaching the return gas section, probes are arranged below the return gas line, which stop the supply of liquid via a valve. The filling process is thus stopped shortly before the return gas line is opened. If the liquid or the foam generated by the filling reaches the first probe, the liquid supply is reduced by means of a throttle device, so that the filling process is continued at a reduced speed. When the liquid or foam reaches the upper probe, the valve is closed and the liquid supply is stopped.

From US-PS 3 918 475 the generic method and an apparatus for performing this method are also known. The device has a long filling tube with two valves for a fast and a slow liquid supply. The filling tube is equipped with two probes. To end the filling process, which takes place at atmospheric pressure, when the liquid or foam reaches a first filling level, the valve that controls the fast flow is closed via the first probe and then, when the second probe is reached, the valve that controls the slow flow is closed controls.

The known methods and devices are not suitable for filling open containers with liquids that tend to foam, especially not when using short filling pipes, since the desired final filling height of the liquid when the filling process is stopped can only be determined inaccurately. When filling liquids, e.g. water, ambient air enters the container at the same time as the liquid. This causes foam and bubbles to form during the filling process, to which the probes respond, even though the liquid level itself has not yet reached the final filling level. The size of the error depends on the size of the foam and bubble formation, which is different for different liquids. This error is clearly noticeable in certain waters. A similar effect can also occur when filling under back pressure.

In view of this prior art, the invention has for its object to provide a method for filling a container and an apparatus for performing this method, with which the accuracy of the final fill level is improved in a simple manner.

This object is achieved according to the invention by a method with the features of claim 1 and a device with the features of claim 7.

Because of the waiting time after the first liquid supply has stopped, the foam which has formed on the liquid surface during the liquid supply is broken down again. This creates a smooth liquid surface, which is located below the first probe. Since, after this waiting time, liquid is again supplied until one of the probes responds again and the liquid supply is then stopped, the container can be filled to the desired final filling level with great accuracy. Since the second filling process is only very short, no new foam forms on the liquid surface, so that the final filling height is achieved in that the liquid itself and not the foam causes the second response of one of the probes. The desired final filling level is thus precisely achieved.

According to an advantageous development of the invention, the liquid supply is interrupted immediately when the probe first responds. This simplifies the control of the device, since the liquid flow is reduced and the device required for this is then not required.

A further simplification of the device can be achieved in that only one probe is used to measure the fill level. The liquid supply is then stopped for the first time when the probe responds due to the foam on the surface of the liquid. The same probe responds a second time if, after the waiting time, during which the foam breaks down, liquid is added again and the now foam-free liquid surface reaches the probe again.

It can also be advantageous if two probes are provided, of which the second probe is arranged above the first probe. The distance between the two probes can be adapted to the filling conditions. This is particularly advantageous when the liquid is supplied quickly or the liquid does not foam too much.

Furthermore, it is advantageous if the probes are arranged on the outside of the filling tube. The height of the probes can then be checked particularly easily by the immersion depth of the filling tube in the container. The probes are also easily accessible for inspection and repair. It is also advantageous if the probes have a metal core which is connected to a voltage source and is insulated from the filling tube by an insulating jacket. These probes can be arranged on the filling tube in a simple manner, have a high measuring accuracy and have a fast reaction time.

It is also advantageous if the probes are surrounded by a protective tube which only leaves the lower ends of the probes exposed. Because then the probes are against harmful influences from the outside world, e.g. Protected from scratching by bumping or being soiled by liquid or air. The free ends define the response points that react to the rising liquid or the foam formed thereon. Conveniently, the outer surface of the fill tube can have recesses into which the probes are inserted so that the outer surface of the probes is substantially flush with the outer surface of the fill tube. It is thereby achieved that the probes do not protrude beyond the outer surface of the filling tube and damage to the probes is avoided.

It is also advantageous if the valve is arranged in the filling tube. Thus, the amount of liquid that is still in the fill tube when the valve is closed can be kept low. It is also advantageous if the filler pipe has a reduced inside diameter below the mouth of the liquid feed line, the transition area to the reduced inside diameter forming an edgeless valve seat on which the valve sits in a sealed manner in the closed state. The continuous transition makes it possible in a simple manner that the valve can assume various open positions, in which a different liquid flow can be regulated by the different distance of the valve from the filling tube wall.

According to a favorable development of the invention, a pneumatic actuator connected to the control device is provided for opening and closing the valve. A pneumatic cylinder is usually used. A simple, reliably controllable opening and closing of the valve is thus made possible. The pneumatic actuator is advantageously designed as a multi-position cylinder. Different liquid flows can then be achieved by different positions of the multi-position cylinder. In particular, a lower liquid flow can then be selected for the second liquid supply, so that an even more precise stopping can take place at the desired final filling level.

According to an advantageous development of the invention, a protective gas line is provided, which opens into a protective gas sleeve surrounding the filling tube above the container to be filled. This is particularly advantageous if the filling tube is inserted into the container without touching and sealing, in order to avoid contamination of the mouth of the container. A protective gas can then be supplied to the container in the region of its mouth during the filling process, so that the container is protected against the ingress of ambient air into its mouth during the entire filling process. In addition, the protective gas line and protective gas sleeve can be used to clean and sterilize the outside of the filling tube, for example by introducing water, hot water, steam, etc., when no container is being filled.

The invention is explained in more detail below with reference to the drawings.

Fig. 1

einen Querschnitt durch ein erstes Ausführungsbeispiel der erfindungsgemäßen Vorrichtung und

Fig.

2 einen Querschnitt durch ein zweites Ausführungsbeispiel der erfindungsgemäßen Vorrichtung.

Show it

Fig. 1

a cross section through a first embodiment of the device according to the invention and

Fig.

2 shows a cross section through a second exemplary embodiment of the device according to the invention.

Fig. 1 shows an embodiment of a filling device 1 in cross section, below which a container 2 in the form of a bottle for filling with a liquid, for example mineral water, is arranged. The filling device 1 comprises a filling tube 3, the lower end of which protrudes into the mouth 4 of the container 2. A liquid supply line 5 opens into the filling pipe 3. The filling pipe 3 has a reduced inside diameter below the opening of the liquid supply line 5. The transition area in the filling pipe 3 to the end with the reduced inside diameter forms an edgeless valve seat 6, on which a valve 7 sits sealingly in the closed state, so that the liquid flow through the filling pipe 3 is interrupted. To control the valve 7, a pneumatic cylinder 8 is arranged which opens or closes the valve 7 via the pressure line 9. The pneumatic cylinder 8 can be designed as a multi-position cylinder, so that different opening positions of the valve 7 are possible are in which liquid flows of different sizes can flow through the filling pipe 3 into the container 2.

At the lower end of the filling tube 3, which projects into the container 2, a recess 10 is formed in the lateral surface of the filling tube 3, into which a probe 11 is inserted. The probe 11 comprises a metal core 12 connected to a control device 17 by means of a line 23 and an insulating jacket 13 and is arranged in the recess 10 in such a way that its surface is substantially flush with the jacket surface of the filling tube 3. To further protect the probe 11, it is surrounded by a protective tube 14 which leaves only the lower end 15 of the probe 11 uncovered. As a result, the probe 11 is completely protected against contamination and the response point of the probe 11 is precisely defined.

The method is described below with reference to the operation of the device according to FIG. 1. The container 2 is filled with liquid through the filling tube 3 until the foam which forms during filling reaches the lower end 15 of the probe 11. A signal is fed to the control device 17 via the probe 11, on the basis of which the pneumatic cylinder is actuated via the pressure line 9, so that the filling process is ended by closing the valve 7.

As a result, the liquid surface lies below the lower end 15 of the probe 11. After a predetermined waiting time of, for example, one second, within which the foam has broken down, the filling process is started again by opening the valve. This second filling process is then stopped again when the liquid reaches the lower one End 15 of probe 11 reached for the second time. The signal goes via the probe 11 to the control device 17, which actuates the pneumatic cylinder 8 and thus closes the valve 7. Since no foam forms due to the short duration during the second filling process, the height of the liquid surface now corresponds to the height of the response point 15 of the probe 11.

Fig. 2 shows a second embodiment of the device according to the invention. The parts of the device numbered with the same reference numerals correspond to those from FIG. 1 and fulfill the mode of operation described in this context, unless otherwise explained below.

vorgesehen, in die eine zweite Sonde 11

eingesetzt ist. Die Sonde 11

umfaßt einen an die Steuereinrichtung 17 angeschlossenen Metallkern 12

, der durch einen Isoliermantel 13

von dem Füllrohr 3 isoliert ist. Ferner fluchtet die Oberfläche der Sonde 11

im wesentlichen mit der Mantelfläche des Füllrohres 3. Die Sonde 11

wird, wie die Sonde 11, von dem Schutzrohr 14 umgeben. Das Schutzrohr 14 weist eine zweite Unterbrechung auf, die das untere Ende 19 der Sonde 11

freiläßt und somit den zweiten Ansprechpunkt definiert.Only the differences from the first exemplary embodiment are therefore described below. In addition to the recess 10 in the lateral surface of the lower end of the filling tube 3, into which the probe 11 is inserted, there is a recess 10 in the lateral surface

provided into which a second probe 11

is used. The probe 11

comprises a metal core 12 connected to the control device 17

by an insulating jacket 13

is insulated from the fill pipe 3. Furthermore, the surface of the probe 11 is aligned

essentially with the outer surface of the filling tube 3. The probe 11

is, like the probe 11, surrounded by the protective tube 14. The protective tube 14 has a second interruption, which is the lower end 19 of the probe 11

leaves free and thus defines the second point of contact.

erreicht hat. Über die Sonde 11

wird ein Signal an die Steuereinrichtung 17 gegeben, die dann über den Pneumatikzylinder 8 und die Druckleitung 9 das Ventil 7 schließt. Da sich während des zweiten nur kurzen Füllvorgangs keine weiteren Blasen oder Schaum bilden, entspricht die Höhe der Flüssigkeitsoberfläche exakt der Höhe des unteren Endes 19 der Sonde 11

, durch welche die vorbestimmte Füllhöhe definiert ist.During the filling process, the lower end 15 of the probe 11 responds to the rising liquid surface or its foam, as a result of which the valve 7 is closed via the control device 17, the pressure line 9 and the pneumatic cylinder 8. During a predetermined waiting time, the foam settles on the surface of the liquid so that it lies below the lower end 15 of the probe 11. After the predetermined waiting time in which the foam has settled, the filling process begins again, as has already been described in connection with FIG. 1. In contrast to the exemplary embodiment in FIG. 1, however, the filling process is only stopped when the liquid surface which rises again has the lower end 19 of the second probe 11

has reached. Via probe 11

a signal is given to the control device 17, which then closes the valve 7 via the pneumatic cylinder 8 and the pressure line 9. Since no further bubbles or foam form during the second short filling process, the height of the liquid surface corresponds exactly to the height of the lower end 19 of the probe 11

, by which the predetermined fill level is defined.

Furthermore, the device 1 is mounted on a support plate 20 in this embodiment. The support plate 20 can be designed as a rotating plate and accommodate several filling devices 1, so that several containers 2 can be filled at the same time. For this purpose, the carrier of the container 2 can be moved in height, so that the filling tube 3 can be led out of the container 2 and positioned in the next container 2 at the desired height.

The filling device 1 also has a protective gas feed line 21 which opens into a protective gas sleeve 22 surrounding the filling tube 3 above the container 2 to be filled. By supplying protective gas via the protective gas line 21 and the protective gas sleeve 22, the mouth 4 of the container 2 can be protected against contamination during the filling process. In addition, the filling tube can be cleaned externally via the protective gas line 21 and the protective gas sleeve 22 by introducing water, hot water, steam, etc., if no containers 2 are filled.

bezüglich des Behälters 2 so zu liegen kommt, daß dort die gewünschte Endhöhe vorliegen soll. Über die Steuereinrichtung 17, die Druckleitung 9 und den Pneumatikzylinder 8 wird das Ventil 7 geöffnet, so daß die Füllflüssigkeit, z.B. Wasser, über die Flüssigkeitszuleitung 5 durch den zwischen dem Ventil 7 und dem Ventilsitz 6 entstehenden Spalt in das untere Ende des Füllrohres 3 und somit in den Behälter 2 gelangt. Die Flüssigkeit steigt in dem Behälter 2 solange an, bis das untere Ende 15 der Sonde 11 von der Flüssigkeit, bzw. dem Schaum auf der Flüssigkeitsoberfläche erreicht wird. Die Sonde 11, die auf die Flüssigkeit bzw. den Schaum auf der Flüssigkeitsoberfläche anspricht, gibt ein Signal an die Steuereinrichtung 17, die das Ventil 7 über die Druckleitung 9 und den Pneumatikzylinder 8 schließt. Die Flüssigkeitszufuhr von der Flüssigkeitszuleitung 5 in den Behälter 2 ist somit unterbrochen. Durch den Einfüllvorgang über das kurze Füllrohr 3 in die offene Mündung 4 des Behälters 2 ist mit der Flüssigkeit bzw. dem Wasser, soviel Luft in den Behälter 2 gelangt, daß die Oberfläche der Flüssigkeit aus Schaum und Blasen besteht. Während einer Wartezeit nach dem Stoppen des Füllvorgangs bauen sich Schaum und Blasen von der Flüssigkeitsoberfläche ab, so daß die Flüssigkeitsoberfläche unterhalb des unteren Endes 15 der Sonde 11 liegt. Nach der Wartezeit, die ausreichend für den Abbau des Schaumes von der Flüssigkeitsoberfläche ist, wird von der Steuereinrichtung 17 das Ventil 7 über die Druckleitung 9 und den Pneumatikzylinder 8 automatisch wieder geöffnet. Das Öffnen des Ventils 7 erfolgt entweder in die ursprüngliche Stellung während des vorherigen Füllvorganges oder in eine Zwischenstellung, in der der Durchlaß zwischen dem Ventil 7 und dem Ventilsitz 6 kleiner ist als während dem ersten Füllvorgang. Der Nachfüllvorgang wird dann gestoppt, wenn das untere Ende 19 der zweiten Sonde 11

auf die erneut ansteigende Flüssigkeitsoberfläche anspricht. Das Ventil 7 wird dann von der Steuereinrichtung 17 über die Druckleitung 9 und den Pneumatikyzlinder 8 wieder geschlossen. Da der Nachfüllvorgang nur sehr kurz ist, entsteht keine erneute Schaum- und Blasenbildung auf der Flüssigkeitsoberfläche, so daß die Höhe der Flüssigkeitsoberfläche exakt der vorbestimmten Füllhöhe entspricht, die durch das untere Ende 19 der Sonde 11

festgelegt ist. Durch Absenken des Behälters 2 oder Anheben der Füllvorrichtung 1 wird das Füllrohr 3 aus der Mündung 4 des Behälters 2 herausgenommen. Dann wird der Behälter 2 zur Verschließstation geführt und ein weiterer Behälter 2 in Füllposition gebracht, so daß der oben beschriebene Füllvorgang von neuem beginnen kann.The method according to the invention is described below with reference to FIG. 2. A container 2 is fed to the filling device 1 arranged on the support plate 20 and positioned at a predetermined suitable height with respect to the filling tube 3. This height is chosen so that the lower end 19 of the second probe 11

with respect to the container 2 comes to lie so that the desired final height should be there. Via the control device 17, the pressure line 9 and the pneumatic cylinder 8, the valve 7 is opened so that the filling liquid, for example water, via the liquid supply line 5 through the gap formed between the valve 7 and the valve seat 6 into the lower end of the filling pipe 3 and thus gets into the container 2. The liquid rises in the container 2 until the lower end 15 of the probe 11 is reached by the liquid or the foam on the liquid surface. The probe 11, which responds to the liquid or the foam on the liquid surface, gives a signal to the control device 17, which closes the valve 7 via the pressure line 9 and the pneumatic cylinder 8. The Liquid supply from the liquid supply line 5 into the container 2 is thus interrupted. Due to the filling process via the short filling tube 3 into the open mouth 4 of the container 2, the liquid or water has so much air in the container 2 that the surface of the liquid consists of foam and bubbles. During a waiting period after the filling process has stopped, foam and bubbles degrade from the liquid surface, so that the liquid surface lies below the lower end 15 of the probe 11. After the waiting time, which is sufficient for the foam to be removed from the liquid surface, the control device 17 automatically opens the valve 7 via the pressure line 9 and the pneumatic cylinder 8. The valve 7 is opened either in the original position during the previous filling process or in an intermediate position in which the passage between the valve 7 and the valve seat 6 is smaller than during the first filling process. The refilling process is stopped when the lower end 19 of the second probe 11

responsive to the rising liquid surface. The valve 7 is then closed again by the control device 17 via the pressure line 9 and the pneumatic cylinder 8. Since the refilling process is only very short, there is no renewed foaming and bubble formation on the liquid surface, so that the height of the liquid surface corresponds exactly to the predetermined filling level, which is caused by the lower end 19 of the probe 11

is set. By lowering the container 2 or lifting the filling device 1, the filling tube 3 is removed from the mouth 4 of the container 2. Then the container 2 is guided to the closing station and another container 2 in Filling position brought so that the filling process described above can start again.

Claims (19)

A method for filling a container with a liquid, in which the liquid is supplied to the container via a liquid feed line, the achievement of a predetermined filling level in the container is measured by means of at least one probe and the liquid supply is stopped after the response of one of the probes, characterized in that after a predetermined waiting time, liquid is supplied again until one of the probes (11, 11

) responds and that the fluid supply is then stopped again. Method according to Claim 1, characterized in that the liquid supply is interrupted immediately when the probe (11) responds for the first time. Method according to Claim 1 or 2, characterized in that only one probe (11) is used to stop the liquid supply for the first and second time. Method according to Claim 1 or 2, characterized in that two probes (11, 11 ') arranged at different heights are used, the liquid supply being triggered when the lower probe (11) responds for the first time when the upper probe (11') responds. is stopped the second time. Method according to one of claims 1 to 4, characterized in that the renewed liquid supply takes place with a reduced liquid flow compared to the first liquid supply. Method according to one of claims 1 to 5, characterized in that protective gas is supplied to the container (2) in the region of its mouth (4) during the filling process. Device for filling a container with a liquid, with a filling tube, with a liquid supply line connected to it, with a controllable valve for interrupting the flow of liquid in the filling tube, with at least one probe for measuring the liquid level in the container to be filled and with a control device for closing of the valve when one of the probes responds, characterized in that the control device (17) is designed in such a way that after the valve (7) is closed it opens again automatically after a predetermined waiting time and when one of the probes (11, 11 ') responds a second time ) is closed again. Apparatus according to claim 7, characterized in that the control device (17) is designed such that the valve (7) is closed immediately when the probe (11) responds for the first time. Device according to claim 7 or 8, characterized in that only one probe (11) is provided. Device according to claim 7 or 8, characterized in that two probes (11, 11 ') are provided, of which the second probe (11

) is arranged above the first probe (11). Device according to one of claims 7 to 10, characterized in that the probes (11, 11

) are arranged on the outside of the filling pipe (3). Device according to one of claims 7 to 11, characterized in that the probes (11, 11

) a metal core (12, 12

) which are separated from the filling tube (3) by an insulating jacket (13, 13

) is isolated. Device according to one of claims 7 to 12, characterized in that the probes (11, 11

) are surrounded by a protective tube (14), which only the lower ends of the probes (11, 11

) releases. Device according to one of claims 7 to 13, characterized in that the outer surface of the filling tube (3) has recesses (10, 10

) into which the probes (11, 11

) are used in such a way that the outer surface of the probes (11, 11 ') is essentially flush with the outer surface of the filling tube (3). Device according to one of claims 7 to 14, characterized in that the valve (7) is arranged in the filling tube (3). Device according to one of claims 7 to 15, characterized in that the filling tube (3) below the mouth of the liquid feed line (5) has a reduced inside diameter, the transition area to the reduced inside diameter forming an edgeless valve set on which the valve (7) sits sealingly in the closed state. Device according to one of claims 7 to 16, characterized in that a pneumatic actuator (8) is connected to the control device (17) for opening and closing the valve (7). Apparatus according to claim 17, characterized in that the pneumatic actuator (8) is designed as a multi-position cylinder. Device according to one of claims 7 to 18, characterized in that a protective gas feed line (21) is provided which opens into a protective gas sleeve (22) surrounding the filling tube (3) above the container (2) to be filled.

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