METHOD FOR FILLING AN AT LEAST PARTIALLY GAS-PERMEABLE CONTAINER

Abstract

A method for filling a receptacle (7), which is at least partly gas-permeable with bulk filling material (2), includes subjecting the receptacle (7) at the outer side to an underpressure, in order to generate a feed of filling material through a filling material conduit (4) into the inside of the receptacle (7). The filling procedure is assisted by way of subjecting the filling material conduit (4) to pressure after completion of a first filling time.

Claims

1. A method for filling a receptacle, which is at least partly gas-permeable, with bulk filling material, the method comprising the steps of: subjecting an outer side of the receptacle to an underpressure, in order to generate a feed of filling material through a filling material conduit into an inside of the receptacle as part of a filling procedure; and subjecting the filling material conduit to pressure after completion of a first filling time of the filling procedure to assist the filling procedure including the feed of filling material through the filling material conduit.

2. A method according to claim 1, wherein the assistance of the filling procedure by way of subjecting the filling material conduit to pressure is maintained up to an end or close to an end of the filling procedure.

3. A method according to claim 1, wherein a duration of the first filling time is from half up to two-thirds of a duration of a complete filling time of the filling procedure.

4. A method according to claim 1, wherein an end of the first filling time is determined by a dropping of a filling speed to a predefined value.

5. A method according to claim 1, wherein a differential pressure closed-loop control between the pressure which prevails in the receptacle and the pressure which surrounds the receptacle is effected.

6. A method according to claim 5, wherein the differential pressure is closed-loop controlled to a value of between 300 mbar and 800 mbar.

7. A method according to claim 6, wherein the differential pressure is closed-loop controlled to a value of between 500 mbar and 700 mbar.

8. A method according to claim 1, wherein the subjecting the outer side of the receptacle to an underpressure is retained up to the end of the filling procedure.

9. A filling device for filling a receptacle, which is at least partly gas-permeable, with bulk filling material, the filling device comprising: a filling material conduit fed from a filling material container; an underpressure chamber, wherein the filling material conduit runs out into the underpressure chamber, wherein the underpressure chamber is arranged and configured for receiving the receptacle which is to be filled and the underpressure chamber is configured to subject an outer side of the receptacle, to be filled, to an underpressure, in order to generate a feed of filling material through a filling material conduit into an inside of the receptacle as part of a filling procedure; sealing means for sealing the filling material conduit with respect to the receptacle which is to be filled and into which the filling material conduit runs; and pressure means for subjecting the filling material conduit to pressure, during the filling procedure after completion of a first filling time of the filling procedure, to assist the filling procedure including the feed of filling material through the filling material conduit.

10. A filling device according to claim 9, wherein the pressure means comprises a membrane pump.

11. A filling device according to claim 9, further comprising: a first conveying conduit; and a second conveying conduit, to provide two conveying conduits running out into the filling material conduit, wherein: one of the two conveying conduits is for conveying an underpressure; and another of the two conveying conduits is for conveying pressure.

12. A filling device according to claim 9, further comprising a control- and closed-loop control device configured to closed-loop control a pressure difference between the inside of the receptacle to be filled and the surrounding space in the vacuum chamber, during the filling procedure.

13. A filling device according to claim 12, further comprising: a vacuum closed-loop control valve; a vacuum pump; and a conduit, wherein the underpressure chamber is connected to the vacuum pump via the conduit, and the vacuum closed-loop control valve, which is controlled by the closed-loop control device, is integrated in the conduit.

14. A filling device according to claim 9, further comprising a shut-off valve integrated in the conveying conduit for conveying underpressure.

15. A filling device according to claim 9, further comprising a shut-off valve provided in the filling material conduit.

16. A filling device according to claim 9, further comprising means for detecting at least one of: a pressure level in the underpressure chamber; a pressure level in the inside of the receptacle to be filled; and a pressure level in the filling material conduit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the drawings:

[0028] FIG. 1 is greatly schematic and simplified illustration of the basic construction of a filling device according to the invention;

[0029] FIG. 2 is a diagram relating to the filling procedure over time, according to the method according to the invention and according to the state of the art; and

[0030] FIG. 3 is a diagram relating to the pressure course during the filing procedure.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0031] Referring to the drawings, the filling device which is represented by way of FIG. 1 includes some mechanical construction features that are essentially configured as are also known from vacuum packers according to the state of the art, and in this context a vacuum packer of GREIF-VELOX Maschinenfabrik GmbH in Lübeck of the type VeloVac is referred to.

[0032] The filling device comprises a supply container 1 for receiving filling material 2, said supply container being connected to a filling material conduit 4 via a conveying conduit 3. A filling spout 5 which ends within a vacuum chamber 6 which is configured for receiving a receptacle 7 to be filled is arranged at the end of the filling material conduit 4. This vacuum chamber 6 which can be closed off with respect to the surroundings in a complete manner is connected to a vacuum pump 10 via a vacuum conduit 8 amid the intermediate arrangement of a vacuum closed-loop control valve 9, and the outlet conduit 11 of this vacuum pump runs out into the outer atmosphere possibly amid the intermediate arrangement of filters.

[0033] Herein, the vacuum chamber 6 is connected to the machine mount via a weighing device 12, with which the filling weight of the receptacle 7 can be determined. A support body 13 which serves for the lateral and base-side support of the receptacle 7 during the filling procedure is arranged within the vacuum chamber 6. This support body 13 is configured in a grid-like manner.

[0034] Furthermore, the filling device comprises a control- and closed-loop control device 14 which at the outlet side is envisaged for the control of the vacuum closed-loop control valve 9 and at the inlet side via a first pressure senor 15 detects the pressure in the vacuum chamber 6 and via a second pressure sensor 16 the pressure within the receptacle 7. This second pressure sensor 16 at the end of the filling material conduit 4 is arranged within the filling spout 5.

[0035] A shut-off valve 17 is arranged in the filling material conduit 4, said shut-off valve being controlled by the control- and closed-loop control device 14 and not only being provided for the opening and closing of the filling material conduit 14, but can also be brought into intermediate positions. A corresponding shut-off valve 18 is provided in the conveying conduit 3 from the supply container 1 to the filling material conduit 4.

[0036] The vacuum chamber 6 can be opened for the purpose of removing a filled receptacle 7 and for bringing in an empty receptacle 7 and the filling spout 5 is sealingly led into the vacuum chamber 6 and is sealed off with respect to the receptacle 7 via a seal 19. The construction which is described above corresponds to that of a vacuum packer according to the state of the art.

[0037] In contrast to this, the filling device additionally comprises a second conveying conduit 20 which is led parallel to the conveying conduit 3, likewise connects the supply container 1 to the filling material conduit 4 and in which a membrane pump 21 is integrated, said membrane pump being controlled by the control- and closed-loop control device 14. Furthermore, the filling device comprises a third pressure sensor 22 which detects the pressure in the filling material conduit 4 between the conveying conduit 3, 20 and the shut-off valve 17. This sensor 22 is also signal-connected to the control- and closed-loop control device 14.

[0038] The filling of a receptacle 7 by the filling device which is described above is herein effected as follows:

[0039] The receptacle 7, for example a valve sack, given an opened vacuum chamber 6 is placed with a filling valve onto the filling spout 5, whereupon the seal 19 which annularly surrounds the filling spout 5 is subjected to pressurized air, by which means this is sealed off with respect to the inside of the valve sack 7. The valve sack is located within the support body 13 within the vacuum chamber 6 which is sealingly closed after placing on the valve sack 7. Given a closed vacuum closed-loop control valve 9, the vacuum pump 10 is then switched on and the filling procedure begins by way of the shut-off valves 17 and 18 being opened and the closed-loop control valve 9 being opened at the point in time t0.

[0040] On opening the closed-loop control valve 9, the vacuum chamber 6 is subjected to an underpressure, by which means a delivery flow of filling material 2 is effected through the conveying conduit 3, the filling material conduit 4 and the filling spout 5, into the inside of the valve sack 7. Herein, the weight of the sack 7 is detected by the weighing device 7. The course of the product weight from the begin of the filling procedure t0 up to reaching the nominal weight at the point in time t2 is represented in FIG. 2 by the dashed curve 25. Herein, the filling of the valve sack 7 up to a point in time t1 is effected exclusively by way of underpressure, thus as is also effected with common vacuum filling technology. During this first filling time which lasts from t0 to t1, the filling of the receptacle 7 is effected exclusively by underpressure in the vacuum chamber 6. The dot-dashed curve 26 in FIG. 2 represents the product flow which is generated by the underpressure. The initially outlined effect of the product flow which is generated by the underpressure dropping more and more after an initially very high product flow is clearly visible by way of the curve 26.

[0041] When the product flow drops to a predefined value or however the speed of the increase of the product weight, as is represented in curve 25, drops to a certain value, then the point in time t1 is reached, which means the first filling time in which one fills exclusively by way of an underpressure is completed. At the point in time t1, the membrane pump 21 is activated in a delivering manner and the shut-off valve 18 in the conveying conduit 3 is activated into closing, so that now apart from the product weight which is generated by underpressure and which is represented in the curve 27 in FIG. 2 by an unbroken line, a further product flow which is caused by the pressure in the conveying conduit 20, said pressure being produced by the membrane pump 21, and subsequently in the filling material conduit 4 additionally kicks in. The filling weight which is additionally generated by the feed pump 21 is represented in the curve 28 in FIG. 2 which is double-dot-dashed. Hence now after the first filling time at the point in time t1 up to the end of the filling time at the point in time t2, a part of the product weight is generated by the underpressure which is generated by the pump 10 and a part of the product weight by the overpressure which is generated by the pump 21. The product weight which is produced by the respective conveying flows sum, so that the curve 25 has reached the nominal weight 23 already at the point in time t2, thus after the end of the filling time. In the example which is represented by way of FIG. 2, it is evident that the duration of the first filling time t0 to t1 contributes to roughly half the complete filling duration t0 to t2.

[0042] For a comparison, in FIG. 2 it is represented how long it would last to reach the nominal weight 23 exclusively by way of vacuum filling. This would not be reached until at a time t3, wherein the filling time which is necessary with the combined underpressure-overpressure filling (duration from t0 to t2) is only roughly half as long as the filling time which is necessary given a purely vacuum filling (duration t0 to t3).

[0043] As the dotted curve 29 which is illustrated in FIG. 2 makes clear, the closed-loop control is effected via the differential pressure between the inside of the sack and the surroundings within the vacuum chamber 6, thus on the basis of the differential pressure which is determined by the sensors 15 and 16. After an initial build up, this is to be closed-loop controlled in a constant as possible manner. In practice, this means given a pressure subjection of the conveying conduit 20 and in the filling material conduit 4, the vacuum closed-loop control valve 9 must be moved back, in order to keep the differential pressure constant. Since the underpressure subjection of the vacuum chamber 6 is to be maintained up to the end of the filling time, thus up to the point in time t2, the underpressure valve 9 is to be activated such that the underpressure is reduced in comparison to that underpressure which is necessary during the first filling time. This is represented schematically by way of FIG. 3 which shows the pressure course over time. There, the differential pressure is represented as a curve 29 corresponding to the curve 29 in FIG. 2. The dashed curve 30 herein shows the pressure which is mustered by the delivery pump 21, whereas the unbroken curve 31 represents the pressure (underpressure) which is produced by the vacuum pump 10 in combination with the vacuum closed-loop control valve 9. The differential pressure 29 results from the addition of the overpressure which is produced by the pump and of the underpressure according to curve 31, produced by the pump 10.

[0044] Basically, this multi-stage filling method can also be effected in pressure levels, but what is decisive is the fact that the allowable pressure difference is not exceeded, which at the same time limits the speed of the filling procedure.

[0045] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

LIST OF REFERENCE NUMERALS

[0046] 1 supply container [0047] 2 filling material [0048] 3 conveying conduit [0049] 4 filling material conduit [0050] 5 filling spout [0051] 6 vacuum chamber [0052] 7 receptacle [0053] 8 vacuum conduit [0054] 9 vacuum closed-loop control valve [0055] 10 vacuum pump [0056] 11 outlet conduit [0057] 12 weighing device [0058] 13 support body [0059] 14 control- and closed-loop control device [0060] 15 first pressure sensor [0061] 16 second pressure sensor [0062] 17 shut-off valve [0063] 18 shut-off valve [0064] 29 seal [0065] 20 further conveying conduit [0066] 21 membrane pump [0067] 22 third pressure sensor [0068] 23 nominal weight [0069] 25 dashed curve, temporal course of the product weight in the receptacle 7 [0070] 26 dot-dashed curve, temporal course of the product flow which is generated by underpressure [0071] 27 curve which shows the temporal course of the product weight in the receptacle 7, said weight being produced by the underpressure [0072] 28 double-dotted-dashed curve which shows the temporal course of the product weight which is produced by the feed pump [0073] 29 dotted curve which shows the pressure difference between the receptacle inside and the inside of the vacuum chamber [0074] 30 a dashed curve which shows the pressure which is generated by the pump 21 [0075] 31 curve which shows the underpressure which is generated by the vacuum pump 10