PACKAGING MACHINE WITH PRESSURE CONTROL DEVICE AND METHOD

Abstract

A packaging machine with an atmosphere modifying station in which an atmosphere within a packaging to be produced can be modified by evacuating air and/or introducing a gas. The packaging machine has a pressure control device that may control an evacuation pressure and/or a gassing pressure. The pressure control device may comprise a first controllable 2/2-way valve and a second controllable 2/2-way valve, both which are configured to influence the evacuation pressure and/or the gassing pressure by setting a volume flow. The first and second 2/2-way valves are connected in parallel with one another and are controllable independently of one another. In one embodiment, the first and second 2/2-way valves are preferably electrically controllable. A method of modifying an atmosphere within a package using a packaging machine and pressure control device is also provided.

Claims

1. A packaging machine having an atmosphere modifying station, in which an atmosphere within a package to be produced is modifiable by evacuation and/or gassing, the packaging machine comprising: a pressure control device for modifying the atmosphere of a package, said pressure control device being configured to control an evacuation pressure and/or a gassing pressure, wherein the pressure control device comprises a first controllable 2/2-way valve and a second controllable 2/2-way valve which are arranged to influence at least one of the evacuation pressure or the gassing pressure by setting a volume flow, the first and second controllable 2/2-way valves are connected in parallel with one another and are controllable independently of the other.

2. The packaging machine according to claim 1, wherein the second controllable 2/2-way valve has a larger maximum flow cross-sectional area than the first controllable 2/2-way valve.

3. The packaging machine according to claim 1, wherein the pressure control device comprises a pressure transmitter, the pressure control device being adapted to consider signals generated by the pressure transmitter as an actual value.

4. The packaging machine according to claim 3, wherein the pressure transmitter is connected to the atmosphere modifying station by a pressure measuring line, the pressure measuring line having a length that is less than one meter.

5. The packaging machine according to claim 1, wherein the pressure control device comprises at least a third controllable 2/2-way valve that is connected in parallel to the first and the second controllable 2/2-way valves and all of the controllable 2/2-way valves are actuated independently of the others.

6. The packaging machine according to claim 1, wherein each of the controllable 2/2-way valves have a different flow cross-sectional area.

7. The packaging machine according to claim 2, wherein a flow cross-sectional area of one of the first or the second controllable 2/2-way valves is twice as large as a flow cross-sectional area of that of the other one of the first and the second controllable 2/2-way valves.

8. The packaging machine according to claim 1, wherein a pressure line is provided as a connection between the atmosphere modifying station and the first and the second controllable 2/2-way valves, the pressure line having a length which is less than one meter.

9. The packaging machine according to claim 1, wherein one of a volume flow set point or a volume flow set point profile can be set by an operator.

10. The packaging machine according to claim 1, wherein the pressure control device determines a volume flow set point profile based on user inputs.

11. The packaging machine according to claim 10, wherein the user inputs comprise one of a desired process speed, a desired fault tolerance, or a weighting between process speed and fault tolerance.

12. A method for modifying an atmosphere within a package by a packaging machine having a pressure control device, the method comprising the steps of: generating a volume flow to the package or away from the package; controlling the volume flow using the pressure control device; wherein controlling the volume flow step comprises the steps of opening and/or closing one or more of at least two 2/2-way valves connected in parallel, and independently actuating at least one of the at least two 2/2-way valves relative to another one of the at least two 2/2 way valves.

13. The method according to claim 12, further comprising the step of determining the evacuation and/or gassing pressure prevailing within the package based on signals generated by a pressure transmitter.

14. The method according to claim 12 further comprising the step of determining a volume flow set point profile based on user inputs entered by an operator.

15. The method according to claim 14, wherein the user inputs comprise one of a desired process speed, a desired fault tolerance, or a weighting between process speed and fault tolerance.

16. The method according to claim 13, wherein the pressure control device comprises at least a third 2/2-way valve that is connected in parallel to the at least two 2/2-way valves and each of the 2/2-way valves are actuated independently of the other 2/2 way valves.

Description

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0022] In the following, an advantageous embodiment of the present invention will be explained in more detail making reference to a drawing, in which the individual figures show:

[0023] FIG. 1 is a schematic side view of one embodiment of a packaging machine in accordance with the teachings of the present invention, wherein the packaging machine is a thermoforming packaging machine; and

[0024] FIG. 2 is a schematic representation of components of one embodiment of a pressure control device and of other components of the packaging machine in accordance with the teachings of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0025] The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. For purposes of clarity in illustrating the characteristics of the present invention, proportional relationships of the elements have not necessarily been maintained in the drawing figures.

[0026] The following detailed description of the invention references specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled.

[0027] FIG. 1 shows a schematic view of a packaging machine 1 according to the invention, embodied, for example, as a thermoforming packaging machine. This packaging machine 1 may have a forming station 2, an atmosphere modifying station 3, e.g. a sealing station, a cross cutting device 4 and a longitudinal cutting device 5. These may be arranged in this order in a working direction R on a machine frame 6. On the input side there may be a feed roll 7 on the machine frame 6, from which a bottom film 8 may be pulled off. The bottom film 8 may be transported to the forming station 2 by a feed device, which is not shown. There, open packages 14 formed as troughs may be formed into the bottom film 8 by deep-drawing. A plurality of adjacent packages 14 may be formed. The open packages 14 may be transported together with the surrounding area of the bottom film 8 to a loading line 15, where they may be filled with the product 16. The filled packaging 14 may then be transported together with the surrounding area of the bottom film 8 to the atmosphere modifying station 3. Since this is a sealing station in this embodiment, they may be sealed there with a top film 10. Sealing the top film 10 onto the open packaging 14 produces sealed packaging 14, which may be separated with the cross cutting device 4 and the longitudinal cutting device 5 and transported away by a discharge device 13.

[0028] The shown sealing station 3 may include a sealing tool lower part 17 and a sealing tool upper part 18, which may interact to seal the packages 14. The sealing tool lower part 17 and/or the sealing tool upper part 18 may be heated for this purpose. After the packaging 14 to be sealed has been moved to a suitable position, the sealing tool lower part 17 and the sealing tool upper part 18 may be brought into a sealing position in which they form a chamber 19 surrounding the packaging 14. For this purpose, the sealing tool lower part 17, for example, may be liftable. Alternatively or additionally, the sealing tool upper part 18 could be lowered.

[0029] The sealing device 3 may include a channel 20 through which a package 14 to be sealed may be evacuated and/or gassed prior to sealing. This may be particularly advantageous when packaging food products, as their shelf life may be increased by vacuum packaging or by inert gases. In particular, it is conceivable that, after evacuation, the packaging 14 is filled with a protective gas, which may be selected according to the product to be packaged. A vacuum source, in this example a vacuum pump 22, may be connected to this channel 20 to generate a vacuum in channel 20. A gas source 21 (see FIG. 2), e.g. a pressure vessel filled with the desired gas, may be provided for gassing. In the present embodiment, both components are present, wherein the gas source 21 is only visible in FIG. 2. A switching device 23, e.g. a 3/2-way valve, may be used to switch between them, for example to first evacuate a package and then fill it with a gas supplied by the gas source 21.

[0030] FIG. 2 shows the vacuum pump 22, the gas source 21, the switching device 23 and the atmosphere modifying station 3. FIG. 2 also schematically shows a pressure control device 24. Its connections to the other components of the packaging machine 1 are also schematically indicated. The pressure control device 24 comprises a plurality of 2/2-way valves 25. This includes a first 2/2-way valve 25a, a second 2/2-way valve 25b and three additional 2/2-way valves 25c, 25d, 25e. The pressure control device 24 may also include a control unit 26, as in the embodiment shown. This may be adapted to control the plurality of 2/2-way valves 25. For reasons of clarity, only one connection of the control unit 26 with the plurality of 2/2-way valves 25 is shown. However, it may also be provided that the individual 2/2-way valves 25a, 25b, 25c, 25d, 25e are each individually connected to the control unit 26. Alternatively or additionally, the individual 2/2-way valves 25a to e may be controlled independently of each other by the control unit 26. The plurality of 2/2-way valves may be connected to the atmosphere modifying station 3 by a pressure line 23.

[0031] The pressure control device 24 may also include a pressure transmitter 27 as shown in the embodiment. This may be connected via a pressure measuring line 28 to the atmosphere modifying station 3 to determine the pressure prevailing there and/or in the 14, 14 packaging. A pressure applied to the pressure transmitter 27 may be converted into an electrical signal by it. Based on this signal, the control unit 26 may determine an actual pressure value.

[0032] The control unit may also be connected to an operating unit 29 of the packaging machine. From there, it may receive user input entered by an operator. The user inputs may already include a volume flow set point or a volume flow set point profile. Alternatively, the control unit 26 may be configured to determine a volume flow set point or a volume flow set point profile from the received user inputs.

[0033] From the volume flow set point or the volume flow set point profile, a suitable transformation procedure may be used to determine how large the total flow cross-sectional area is to be at different times in the evacuation and/or gassing process. Suitable valve combinations, which provide these total flow cross-sectional areas when they are opened, may then be determined for the respective total flow cross-sectional areas. The control unit 26 may then open the determined valve combination at the corresponding time, for example the first valve 25a at the start of the process, then the first and second valves 25a, 25b and one of the additional valves, for example 25d, and towards the end of the process only the first valve 25a. Hysteresis may be used in the transformation process of the continuous volume flow set point profile into the discrete valve opening times in order to avoid unnecessary valve switching cycles.

[0034] From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting.

[0035] The constructions and methods described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention.

[0036] As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms having and including and similar terms as used in the foregoing specification are used in the sense of optional or may include and not as required. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.