EP0366997A1 - Method for deaerating a filling installation, and device for performing the method - Google Patents

Abstract

Method for deaerating an installation for filling containers (2) with a metered amount of liquid not including any air by means of a metering pump (9), in which two control valves (11', 12') arranged at the inlet of a filling tube (4) are intermittently opened and closed, and the liquid (17) is conveyed via a buffer container (13). <??>In order to prevent the faulty filling of initial production material at the beginning of the filling operation, and in order to be able to specify as accurate a switched-on period as possible for the actual filling operation, it is provided according to the invention that, in order to deaerate the filling tube (4) and the metering pump (9) connected thereto, two control valves (11', 12'), connected in series, are controlled separately from each other in such a way that when the vacuum is generated in the buffer container (13), both control valves (11', 12') are opened; after the majority of the air has bubbled off upwards, firstly the upper control valve (12') and, after a period of time which can be set, the lower control valve (11') are closed; and then the upper control valve (12') is opened and, after a further time interval, is closed. <IMAGE>

Description

The invention relates to a method for venting a system for filling containers with a metered amount of liquid without air inclusion by means of a metering pump, in which at least one control valve arranged at the inlet of the filling tube is opened and closed intermittently and the liquid is supplied via a buffer container. In addition, the invention relates to a device for venting such a system for filling containers with a metered amount of liquid without air, and this device has a buffer container connected to a feed line, under which a control valve housing with at least one control valve is arranged, which is the input side of a the filling tube located below it, which can be closed at the outlet with a filling nozzle, is closed or connected to the buffer tank.

In the case of liquid packs, the main body of which consists of a tube which is open on one side at the top, a system for filling with a metered amount of liquid without air inclusion is known, for example milk. Filling without the inclusion of air, however, requires various measures, in particular venting at the beginning of the filling operation, if, for example, a change has been made to a different type of pack or a different filling material. In the known case, milk is fed from a central distribution via a feed line to the buffer container and, controlled by valves, conveyed into a filling pipe arranged under the valves, at the exit of which the tubular milk pack to be filled is located. Air can now collect in this fill tube, and the invention aims to provide measures to remove this air.

At the beginning of the entire filling process, there is trapped air in various parts of the system, which begins with the pumping and filling of the packs is inevitably promoted into the packs. One wishes to avoid this.

In the case of the previous filling systems, in the case of milk, 10 packs are therefore filled in advance with milk from the plant parts with air pockets, so that the packs are not completely filled. That is why they are treated as a committee. If you fill in a product with a thicker consistency, e.g. Yogurt, then 25 packs are generally filled as rejects for the start of a filling process, because experience has shown that after the 25th pack has passed, no more air can be expected.

In the production state, all pipes in the system should be completely filled with air and only with filling material, so that the packs can actually be filled with a metered quantity. The known metering pumps generally have a piston, the pump stroke of which specifies the metered amount of liquid which is filled into the package.

For a dairy or other filling plant, in which liquids have to be filled in a large number of packs of different batches or with different contents, it is understood that each time before the production operation or after a change in the system, the production of rejects is only due to the ventilation of the Plant is undesirable.

The invention is therefore based on the object of a method for venting such a system with the aforementioned

To create features in which the advance of production goods at the beginning of the filling process with incorrect filling is avoided; and, if possible, an exact switch-on time for the actual filling process can be specified, in which it is ensured that there are no more air pockets in the system.

The task also applies to the improvement of a device for venting such a system with those mentioned above Features that allow a time-definable working method for venting, after which the filling operation can preferably be started by a simple push of a button at a time at which the operator can reasonably expect that the system no longer has any air pockets.

With regard to the method, this object is achieved in that a vacuum is generated in the filling tube provided on the outlet side with a filling nozzle and in the buffer tank while closing the filling nozzle, the control valve being opened, and in that after the air has bubbled upward after an adjustable time interval the control valve is closed. The person skilled in the art understands that when a vacuum is applied to the space above the liquid level in a buffer container, any air inclusions which are located in the buffer container or in parts of the system below it can bead out or receive a greater buoyancy than without a vacuum. Air pockets are generally driven upward over time by vibrations and the like, but bends in the pipe system and the like generally take a long time to remove all air pockets with great certainty. At the beginning of the filling operation, the shortest possible time for expelling the air inclusions is desired. By creating the vacuum, this is surprisingly easy and easy. If the filling tube is closed at the top by the control valve mentioned, the control valve is opened for venting, so that liquid present in the filling tube can be held and at the same time air enclosed therein can rise upwards. After a period of time, this control valve is closed, any other work, including bleeding, can be done and then the production operation can begin. This time interval is set based on experience and by qualified specialists. The same setting of the time interval then applies to the same system and the same filling material, so that after the completion of the development work for the new venting process, these empirical values can be used without a qualified specialist again with each filling process to have to use the man to set the time interval.

Since the filling tube is closed on the outlet side with the filling nozzle, the venting method can be carried out according to the invention without filling packs, so that considerable savings can be made in rejects.

The use of vacuum in filling systems is already known per se in another context. For example, there is already a device for the intermittent supply of liquid with a drip-free valve, the liquid being supplied to a buffer container being arranged below the valves. Devices create a vacuum in the buffer tank. However, this vacuum is intended to reduce the hydrostatic pressure in the line area with the valves, which the liquid would otherwise generate at the valves. Due to the vacuum, the return springs of the valves can be set so that they always close or open at the right moment, which is particularly important for the foam-forming milk. However, the vacuum provided by this known method cannot be used to vent the filling system. It has also been shown that the response of spring-loaded valves is delayed too much.

On the other hand, it is particularly expedient according to the invention if, for venting the filling pipe and the metering pump connected to it, two control valves connected in series are controlled separately from one another in such a way that both control valves are opened when the vacuum in the buffer tank is generated; after the substantial part of the air has been bubbled upwards, the upper control valve is closed and, after an adjustable time, the lower control valve is closed; and then the upper control valve is opened and closed after another time interval. If several system parts are vented using the method according to the invention, several control valves should be arranged separately from one another and operated in the manner described. With one preferred In addition to the filling pipe, there is also the dosing pump connected to its filling area, ie two branches of the plant that have to be vented, which is why the two control valves are arranged separately and actuated separately. In this way, one branch can be vented first and closed in this clean state and then the other branch of the system can be vented.

Furthermore, it is expedient according to the invention if the vacuum is first generated in the buffer container, the lower control valve is closed and the upper control valve is opened; then both valves are opened at the same time; after which the upper one is closed, then the lower one is closed, the upper one is opened and finally the upper control valve is closed again, while the filling nozzle remains closed all the time. With such a method, air inclusions can be removed with certainty after a certain time, so that a certain program is run at fixed time intervals, after the completion of which the system can be automatically signaled to start. Even inexperienced operating personnel can then start the filling operation with a simple push of a button. But that means an automatic ventilation without waste product. It also saves the experienced operating personnel, who have to estimate from the experience of conventional venting of such filling machines when there are no longer any air pockets in the system. This automation of the filling process or the upstream venting process is simple, not susceptible to faults and allows personnel to be saved in the general operation of the system user.

The venting method of this type is already very well thought out, but can be improved with regard to a further detail. For example, a filling tube closed on the outlet side by a filling nozzle is assumed, and a liquid column which has a certain weight can be assumed above the outlet-side filling nozzle. Become out of this Liquid column Removed air inclusions by the method according to the invention, one must expect an increase in weight or an increase in the liquid column, because the expelled air is replaced by the liquid, so that a greater weight acts on the outlet filling nozzle. It is therefore advantageous according to the invention if the vacuum in the buffer container is increased when the lower control valve is opened for the first time. With the venting method according to the invention, air pockets can be removed from the filling pipe above the filling nozzle on the outlet side by opening the lower control valve for the first time, so that the weight increase begins at this moment, which is neutralized again by the increased vacuum.

This equalization of the pressure force on the filling nozzle at the outlet end of the filling pipe by the increased suction force of the increased vacuum is particularly expedient if a filling nozzle that closes due to the negative pressure in the filling pipe is used. The increase in weight when expelling the air inclusions could otherwise cause the filling nozzle to open partially because the closing force is no longer sufficient. This risk is advantageous due to the intermediate step of increasing the vacuum in the buffer container and thus above the liquid column of the filling tube and can be eliminated again with simple means.

With regard to the device for venting the filling system, the above-mentioned object is achieved according to the invention in that the control valve is positively controlled from the outside and the buffer tank is connected to a vacuum pump. The positive control according to the invention acts on the one hand on the control valve and on the other hand on the drive of the vacuum pump, so that both units, the control valve and the vacuum pump, develop their effects in the ventilation system according to a certain program. So far, valves have generally been controlled by the state of the adjacent fluid, and in the case of liquid filling systems, the pressure of the filling material inside the system is a spring force had to overcome before the relevant valve provided with this spring could be actuated. The forced control of the new valve in the ventilation device not only makes its function more reliable, so that 100% closing is ensured after the switching access has been completed (the same when opening), but the switching function is also shortened because the valves are controlled from the outside can react faster.

By connecting the buffer tank to the vacuum pump, which can also be controlled as part of the program, the expulsion of the air inclusions can be considerably accelerated in the manner described above. The features of the ventilation device according to the invention therefore make it possible to vent a filling system in the shortest possible time, so that the operator of the filling system can bring the system into the normal operating state without air inclusions in an optimally short time.

It is also particularly advantageous according to the invention if an upper, externally separately controlled control valve is arranged at a distance above the lower control valve and if the connecting line of the metering pump is connected to the control valve housing between the lower and the upper control valve. With these measures, the above-mentioned operating mode can be achieved, namely to vent the metering pump located in one of the two operating branches of the system located below the buffer tank independently and / or simultaneously with the filling pipe in the desired manner.

It is also expedient according to the invention if the filling nozzle consists of an elastomeric material. For example, a rubber filling nozzle can be used which, when closed, has two cross-shaped slots which are kept closed by the negative pressure located behind it inside the filling tube. In another context, there are already such rubber nozzles that are close at negative pressure in the filling pipe. Such a rubber nozzle has the natural tendency to close, which is why a low vacuum in the tube above the rubber nozzle relative to the outside atmosphere is sufficient to close or keep the nozzle closed. With such a rubber nozzle, a liquid column can be held in a completely closed filling tube above the closed nozzle without the risk of dripping. However, the use of such a rubber nozzle in a venting device of the type described here has hitherto not been known.

If, in a further advantageous embodiment of the invention, the control valves and / or the vacuum pump are connected to a computer control, the advantages of rapid and reliable ventilation described above can be achieved. It is state of the art today to feed simple or complicated programs into a computer which can output control signals in a time-controlled manner with great accuracy, so that the venting method described here can be carried out in a precisely timed manner with great reliability.

• Figur 1 schematisch und abgebrochen die wesentlichen Teile der Entlüftungsvorrichtung gemäß der Erfindung in einem ersten Zustand,
• Figuren 2 bis 4 die gleiche abgebrochene Darstellung wie Figur 1, wobei jedoch die Zustände 2 bis 4 gezeigt sind und
• Figur 5 in vollständigerer Darstellung einen Teil einer Füll­anlage, um eine Flüssigkeit in eine Reihe von auf ei­nem Förderband befindlichen Packungen einzufüllen.

Further advantages, features and possible uses of the present invention result from the following description of a preferred exemplary embodiment in conjunction with the drawings. Show it:

• FIG. 1 shows schematically and broken off the essential parts of the ventilation device according to the invention in a first state,
• Figures 2 to 4, the same broken view as Figure 1, but the states 2 to 4 are shown and
• FIG. 5 shows a part of a filling system in a more complete representation, in order to fill a liquid into a row of packages located on a conveyor belt.

The general features can best be explained from the illustration in FIG. 5, where on the schematically arranged conveyor belt 1 there is a liquid pack open on one side at the top kung 2, the lower, with a filling nozzle 3 made of rubber end of a filling tube 4 surrounds. In the state of FIG. 5, the filling nozzle 3 is shown largely immersed in the pack 2. It can be provided in a suitable system for filling paper packs with a metered amount of milk, a relative movement between the filling tube 4 and the pack 2, so that when the pack is empty, the filling nozzle 3 almost reaches the bottom of the pack 2 and here the filling process during slowly pulling the filling tube 4 out of the pack 2. Since the filling process as such is not important for the explanation of the process steps and device features of interest here, the above description of the filling should suffice.

On the inlet side 5 of the filling pipe opposite the outlet of the filling pipe 4 with the filling nozzle 3, connected upwards, a control valve housing 6 is provided, which is designed in the form of a cylinder jacket with a side opening 7, from which the connecting line 8 of a metering pump 9 is branched, namely from a space 10 above the seat 11 of the lower control valve 11 'and under the valve seat 12 of the upper control valve 12'. Both control valves 11 'and 12' are shown closed in the state of Figure 5. In addition, they appear highly schematic with the actuating rods protruding outside the control valve housing 6, which are only intended to symbolically illustrate the positive control of the control valves 11 ', 12' from the outside.

Above the control valve housing 6 there is a buffer tank 13, which is provided on one side (bottom left here) with a feed line 14 and on the other side (top right here) with a vacuum line 15 and a vacuum pump 16. The black space 18 arranged above the corrugated dividing line 20 above the liquid mass 17 with the gas-tightly closed lid 19 of the buffer container 13 represents the vacuum.

In operation, the venting device works with the two at a distance a control valves 11 'and 12' arranged one above the other as follows:

It is assumed that below the level 20 of the liquid 17, the entire system, including the metering pump 9, is filled with the liquid to be filled at the start of a production operation. Trapped air must now be expelled as follows. The buffer container 13 is evacuated via the vacuum pump 16, so that a first specific vacuum is established in the space 18. It is understood that above the closed upper control valve 12 'trapped air is withdrawn through this vacuum through the vacuum line 15. It is assumed that the state in FIG. 5 is assumed, a partial vacuum also being generated in the space of the filling tube 4, by means of which the filling nozzle 3 is closed.

The pack 2 is no longer shown in the further FIGS. 1 to 4, and the buffer container 13 is also broken off at the top. During the entire operational sequence in the venting according to FIGS. 1 to 5, the filling nozzle 3 can be regarded as closed.

After the vacuum in room 18 has been set, the state of FIG. 1 is switched to, i.e. the upper control valve 12 'is opened. Air inclusions located in the area of the metering pump 9 can now be removed upward into the buffer container 13 in the direction of the arrows 21. The liquid column located above the piston of the metering pump 9 is therefore also under the vacuum shown. The first subspace, i.e. the left branch of the venting device with the connecting line 8 is thus vented.

It is still switched to the state of Figure 2, ie the lower control valve 11 'is opened. The upper control valve 12 'remains open. Air enclosed in the filling tube 4 can now escape upward into the buffer container 13 according to the arrows 22, whereby if necessary the vacuum pump 16 begins to work in order to bring the vacuum reduced by the incoming air back to the desired value.

By opening the lower control valve 11 ', the liquid column in the filling tube 4 is larger and also heavier by the additional liquid which replaces the escaping air. So that the filling nozzle 3 remains closed and to compensate for this weight increase, the vacuum pump 16 is switched on after a special part of the computer program in order to set the level of the vacuum in the room 18 to an increased value. As a result, the filling nozzle 3 made of rubber remains closed, although the suction of small amounts of gas (air) from below into the filling pipe 4 cannot be completely ruled out, although there is no leak-tightness. This air bubbled in from below also migrates upwards according to the paths shown by the arrows 22.

Is now switched to the state of Figure 3 by the fact that the upper control valve 12 'is closed, then two things happen; firstly, the high liquid column is reduced from line 20 down to the filling nozzle 3 because the part of the liquid column located above the upper control valve 12 'is cut off; and there is also a slight decrease in the vacuum in the filling tube 4, so that the sucking in of tiny air bubbles from the atmosphere below into the filling nozzle 3 stops. It is now waited until these sucked-in air bubbles from the state when the upper control valve 12 'was still open have climbed up into the space 10 within the control valve housing 6, so that they are in the form shown at the top in FIG. 3 at 23 collect. Now the lower control valve 11 'is also closed, and it can be assumed that the liquid in the filling tube 4 from the filling nozzle 3 to the lower control valve 11' is properly vented.

The air collected at 23 is now removed from the system by switching to the state in FIG. 4.

That is, when the lower control valve 11 'is closed, the upper control valve 12' is now opened, so that the air pockets are removed according to the arrow 24 upwards into the buffer container 13. One can now rightly and experience assume that the left branch with the connecting line 8 and the metering pump 9 is just as well vented as the filling tube 4. Therefore, the upper control valve 12 'can be closed after a certain time interval, so that the state again 5 is reached.

This completes the venting process and the operation of the filling with the aid of the metering pump 9 into the packings 2 can begin - without air pockets.

Claims (8)

1. A method for venting a system for filling containers (2) with a metered amount of liquid without air inclusion by means of a metering pump (9), in which at least one control valve (11 ', 12') arranged at the inlet of a filling tube (4) is opened intermittently and is closed and the liquid (17) is supplied via a buffer container (13), characterized in that in the filling tube (4) provided on the outlet side with a filling nozzle (3) and in the buffer container (13) with closing of the filling nozzle (3) a vacuum is generated, the control valve (11 ', 12') being opened, and that after the air has bubbled upwards, the control valve (11 ', 12') is closed after an adjustable time interval. 2. The method according to claim 1, characterized in that for venting the filling pipe (4) and the metering pump connected thereto (9) two series-connected control valves (11 ', 12') are controlled separately from each other such that when the vacuum is generated in the buffer tank (13) both control valves (11 ', 12') are opened; after the essential part of the air has been bubbled upwards, the upper control valve (12 ') and after an adjustable time the lower control valve (11') are closed; and then the upper control valve (12 ') is opened and closed after a further time interval. 3. The method according to claim 1 or 2, characterized in that first creates the vacuum in the buffer container (13), the lower control valve (11 ') is closed and the upper control valve (12') is opened; then both control valves (11 ', 12') are opened simultaneously; then the upper (12 ') closed, then the lower (11') closed, the upper (12 ') opened and finally the upper control valve (12') is closed again, while the filling nozzle (3) remains closed all the time. 4. The method according to claim 3 or 4, characterized in that the first time the lower control valve (11 ', 12'), the vacuum in the buffer container (13) is increased. 5. Device for venting a system for filling containers (2) with a metered amount of liquid without air inclusion, with a buffer container (13) connected to a feed line (14), under which a control valve housing (6) with at least one control valve (11 ' , 12 ') is arranged, which closes the inlet side (5) of a filling tube (4) located below it, which can be closed at the outlet with a filling nozzle (3), or connects it to the buffer tank (13), characterized in that the control valve (11', 12 ') is positively controlled from the outside and the buffer tank (13) is connected to a vacuum pump (16). 6. The device according to claim 5, characterized in that an upper, separately positively controlled control valve (12 ') is arranged at a distance (a) above the lower control valve (11') and that the connecting line (8) of the metering pump (9) on the control valve housing (6) between the lower (11 ') and the upper control valve (12') is connected. 7. The device according to claim 5 or 6, characterized in that the filling nozzle (3) consist of an elastomeric material. 8. Device according to one of claims 5 to 7, characterized in that the control valves (11 ', 12') and / or the vacuum pump (16) are connected to a computer control.

Images