MACHINE FOR VACUUM PACKING PRODUCTS IN PLASTIC BAGS OR RIGID CONTAINERS

Abstract: A machine (1) for vacuum packing in plastic bags and rigid containers (37) comprising: - an airtight chamber (4), suited to accommodate a plastic bag (26) with the relative product (27), - means for sucking air from said chamber (4), so as to create a vacuum in the chamber and in the bag (26) contained therein, - means for sealing the edges (25) of the bag (6) after the vacuum has been created therein, - air input means (13) for introducing air into the chamber (4) to remove the vacuum, - a suction device (35), connected to the suction means, for creating vacuum in rigid containers (37) provided with a valve (39).

Description: MACHINE FOR VACUUM PACKING PRODUCTS IN PLASTIC BAGS OR RIGID CONTAINERS DESCRIPTION The present invention refers to a machine for vacuum packing products in plastic bags and rigid containers, particularly for preserving foodstuffs and perishable materials in general under vacuum. As is known, almost all foodstuffs, whether they be solid, semi-solid or liquid, tend to deteriorate rapidly when they are in contact with air, following aggression of the components contained therein, particularly oxygen. "Oxidation" of foodstuffs can be avoided by resorting to vacuum storage thereof. Although suction devices for creating vacuum in containers exist, this method of preserving foodstuffs is not very widespread among domestic consumers because of the drawbacks of the suction system, which will now be briefly illustrated. First of all, known suction devices are very expensive, bulky and heavy, so they must form fixed installations, at least during use. These apparatus are in fact fixed to the wall or disposed on a flat surface and are connected to the valve of the container in which the vacuum is to be created by means of a flexible tube. As far as the inside structure of said apparatus is concerned, they have: either an electric motor, on the output shaft of which is a cam which directly drives the piston of a suction pump or types of rotary blade pumps. Both solutions require a rather high power and therefore over-sizing of the entire device. These problems of size and cost are solved by known devices for the creation of vacuum in rigid containers. Said devices comprise a shell consisting of a portable handgrip inside which is housed a suction pump driven by a motor through a reduction unit. The extreme miniaturization of the motor and suction pump assembly leads to unsatisfactory results and an excessively long time for creation of vacuum. The same type of device is used for the creation of a vacuum in plastic bags. In this case, after having cut a plastic bag and filled it with the material to be vacuum packed, the end edges of the bag are closed in a special machine to which a device for creating a vacuum is applied. Consequently this machine also gives unsatisfactory results and takes a long time to create a vacuum. Moreover, the method for creating a vacuum in plastic bags by suction, requires that at least one of the walls of the bag be made with an embossed film, so that when the open edge of the bag is closed in the suction chamber of the machine, between two opposite gaskets, there is not a complete seal between the inner surfaces of the bag walls, which would prevent air suction, but rather channels are created though which air can leave the bag. Furthermore embossing is a process which, besides stiffening the sheet material and thus making it less suitable for the purpose, increases the final costs of packaging. The object of the present invention is to provide a machine for vacuum packing in plastic bags and rigid containers, which ensures high performance and short times for creation of vacuum and which at the same time occupies little space, is cheap, practical and simple to make. This object is achieved in accordance with the invention with the characteristics listed in appended independent claim 1. Advantageous embodiments of the invention are apparent from the dependent claims. The machine for vacuum packing in plastic bags and rigid containers according to the invention has a box-type shell consisting of a base and a cover forming a chamber in which a bag in which a vacuum is to be created is placed. A seating to accommodate a suction pump for creation of the vacuum, driven by a motor, is provided in the walls of said box. Said pump is connected by means of a flexible tube to a device in the form of a handgrip, positioned in a seat on the outside of the box-type shell. Said device has a suction nozzle which can be inserted in a valve provided in the outer wall of the box-type shell and communicating with the inner chamber thereof. In this manner, when the suction pump is operated, a vacuum is created in said chamber and consequently also in the bag contained therein. Once the air contained inside the chamber and consequently inside the bag has been evacuated, that is when the desired level of vacuum has been reached, a slide is operated by means of a cam which pushes the resistance bar upward for heat sealing of the edges of the bag. Simultaneously with the movement of the slide, the cam actuates opening of an air valve which introduces air from the outside into the vacuum chamber. The chamber is thus brought to atmospheric pressure to allow subsequent opening of the cover by the user. The heat seal previously carried out on the edges of the bag prevents the outside air from re-entering the bag, and thus the pressure difference that has been created between the inside of the bag and the outside atmosphere causes flattening or shrinkage of the bag around its contents. The handgrip device can be extracted from its seat and the suction nozzle can be fitted into the valve of rigid containers in which a vacuum must be created. It must be considered that the entire structure of the machine according to the invention is made of thermoplastic resin, with the consequent advantage of being extremely light and cheap. Moreover, the fact that a special housing is provided for the motor and the suction pump for creation of vacuum has enabled the reduction units of the motor to be developed in an optimal manner to exploit greater power, which makes it possible to achieve satisfactory conditions and short times to reach a vacuum, without thereby increasing wear on the structural parts of the suction pump. Moreover, the fact that the bag is housed in an inner chamber of the machine in which vacuum is created, makes it possible to use any type of bag, even without embossing. In fact the bag which is contained inside the chamber of the machine is emptied of air from its mouth, irrespective of the configuration of the sheet material from which it is made. Another advantage of the machine according to the invention is that it can be used indifferently to create a vacuum both in plastic bags and in rigid containers. Further characteristics of the invention will be made clearer by the detailed description that follows, referring to a purely exemplary and therefore non-limiting embodiment, illustrated in the appended drawings, in which: Figure 1 is an axonometric exploded view of the machine for vacuum packing in plastic bags and rigid containers according to the invention; Figure 2 is a longitudinal sectional view of the machine in Figure 1 assembled, showing a bag therein with material to be vacuum packed; Figure 2a is an enlarged sectional view of the detail enclosed in the circle a of Figure 2; Figure 3 is a cross sectional view along sectional plane III-III of Figure 2; Figure 4 is an axonometric view of the machine according to the invention shown assembled and open, during creation of a vacuum in a rigid container; Figure 5 is an axonometric exploded view of the components making up the heat sealing device for bags forming part of the machine according to the invention; Figure 6 is a broken off sectional view taken in the longitudinal direction of the machine and illustrating the heat welding device of Figure 5 assembled,; Figure 7 is a cross sectional view of the heat welding device along sectional plane VII- VII of Figure 6; Figure 8 is an enlarged longitudinal sectional view of a part of the machine according to the invention, schematically illustrating the air flow during the work cycle of the machine; Figure 9 is an axonometric exploded view of a pump for creating vacuum of the machine, according to the invention; Figure 10 is a sectional view of the pump for the creation of vacuum shown in Figure 9. With reference to said figures, a machine according to the invention has been indicated as a whole with reference numeral 1. It essentially comprises a base body 2 and a cover 3 which can be raised by rotation around a rear hinge axis. As shown in Figures 1 and 2, an inner wall 2A of the base body 2 defines a chamber 4 wherein is housed a bag 26 having the material 27 to be vacuum packed inside it. The chamber 4 is tightly closed when the cover 3 is in the lowered position. The cover 3 presses on a special gasket 5 housed in a seat in the upper part of the base or basic body 2. As shown in Figure 2a, the gasket 5 is made in a loop with a lip-shaped section to compensate for errors in planarity of the cover 3 and of the upper part of the basic body 2, due to assembly tolerances. A housing 7, separate from the chamber 4, is provided in the front part of the basic body 2. The following elements are located in the housing 7: - an electrical transformer 10 to transform the electrical current coming from the power supply into an electrical current able to supply the electrical devices of the machine; - a suction pump 33 operated by a relative drive motor M to create vacuum; - a tube winding device 12 consisting of a spring-loaded reel to wind a tube 36 connected respectively to the suction pump 33 and to a device 35 in the form of a handgrip for creating the vacuum; - a geared motor 8 to operate a device for heat sealing the edges 25 of the bag 26 to be vacuum packed. As shown in Figures 5-7, the geared motor 8 rotates a cam 16 positioned in a seat 2B in the upper part of the basic body 2. The cam 16 is insulated from the chamber 4 by means of an airtight gasket 6, mounted around the shaft of the geared motor 8. The cam 16 has a vertical pin 11 that acts in a transverse recess 9 (directed in the longitudinal direction of the machine) of a slide 18. In this manner rotation of the cam 16 causes a translation of the slide 18 with a reciprocating movement obligatorily in the direction x of Figure 5. A resistance holding bar 19 free to slide vertically is mounted on the slide 18. For this purpose the resistance holding bar 19 has two vertical pins 17 which can slide vertically inside respective bushings 20 formed in the seat 2B. Two horizontally disposed pins 46 are mounted on the slide 18 and engage in respective slots 30, with a cam profile, formed in the resistance holding bar 19. The slots 30 generate an obligatory course for the horizontal pins 46 of the slide 18. In this manner the horizontal translating movement of the pins 46 integral with the slide 18 cause a vertical translating movement of the resistance holding bar 19 in the direction z in Figure 5. An electrical resistance 28 kept taught by means of clips 31 disposed at the outer sides of the resistance holding bar is mounted on the resistance holding bar 19. Springs 32 disposed in special seats inside the resistance holding bar 19 press on the clips 31. The bushings 20, besides acting as guides, conduct low-voltage current to the electrical resistance 28 which extends for the entire length of the resistance holding bar 19. When the electrical current passes through the electrical resistance 28, the resistance overheats, reaching an optimal temperature to cause heat sealing of the edges of bags made of heat- weldable plastic material. Rotation of the cam 16 causes horizontal translation of the slide 18 and thus raising of the resistance holding bar 19, which is pushed against a metal bar or counter-bar 22. The metal bar 22 is locked in a bridge structure 21 integral with the basic body 2. The bridge structure 21 packs the entire heat welding system to the basic body 2. The metal bar 22 is situated at a short distance above the resistance holding bar 19. The metal bar 22 is coated with a soft coating 23, for example silicone rubber, which ensures an adequate resistance at the high temperatures reached by the resistance 28 on the resistance holding bar 19. Said coating 23 allows any errors of planarity between the two edges 25 of the bag 26 which must be welded to be compensated for. As shown in Figures 6 and 8, the cam 16 situated in the seat 2B of the upper part of the base body 2 has the task, at the end of the welding cycle, of operating an air valve 13 for input of air from the outside into the chamber 4. The air valve shutter in fact obstructs an opening communicating with the chamber 4. Moreover, the air valve 13 operates a switch 15 (Figure 7) which controls the start and end of the work cycle of the machine. As shown in Figures 1 and 4, in the upper part of the housing 7 a seat 34 is formed which receives a device 35, in the shape of a handgrip, connected by means of a small tube 36 to a suction outlet 69 of the pump 33. The small tube 36 is wound by means of the tube winding device 12. As shown in Figure 4 vacuum can be created in rigid or substantially rigid containers 37 by means of the device 35' by positioning the suction nozzle 38 thereof on the valve 39 of the container lid 37. As shown in Figure 2, a connector 40 accessible from the outside and communicating with the chamber 4 is provided in the seat 34. To be precise, the connector 40 is connected to a tube 41 which passes through the housing 7 and ends in an opening 42 formed in the seat 2B and communicating with the chamber 4. In this manner, when the nozzle 38 of the device 35 is engaged in the connector 40, a vacuum can be created in the chamber 4. As an alternative to the connector 40, a flow deflector which switches the suction output 69 of the pump 33 between the tube 36 directed to the device 35 and the tube 41 directed to the opening 42 of the chamber 4 can be provided. In this manner, to create a vacuum in the chamber 4, use of the handgrip device 35 and the tube winder 12 is avoided. As shown in Figure 4, in the front part of the basic body 2, next to the seat 43, a multi- position selector switch 44 that can be operated by the user to select the level of vacuum desired is provided. The switch 44 acts on a manostat 45 (Figure 1) able to maintain the pressure, or rather the vacuum, in the chamber 4 at the level selected by the user. As shown in Figure 2, downstream of heat welding, a stop 47 is provided on the basic body which acts as a reference for correct positioning of the end edges 25 of the bag 26. As shown in Figure 4, switches 29 sensitive to lowering of the cover 3 are provided in the base body 2, below the cover 3. Said switches send a control signal to enable start-up of the suction pump 33. In the case of use of the handgrip 35 to create a vacuum in rigid containers 37, the suction pump start-up control is provided with a switch 43 (Figures 2 and 4) situated beneath the seat 34. This switch 43, when freed by the handgrip 35, gives out an electrical signal toward the pump 33 to set it in operation. In this manner, to control operation of the suction pump 33, it is not necessary to act on the cover 3 to activate the pump start-up switches 29. Operation of the machine 1 according to the invention will now be described. First of all, the bag 26 is filled with the material 27 to be vacuum packed. The cover 3 is then opened and the bag 26 is positioned in the chamber 4. The end edges 25 of the bag 26 must be situated in the gap between the resistance bar 19 and the coating 23 of the metal bar 22. To ensure correct positioning of the edges of the bag, these edges are placed up against the stop 47. The desired level of vacuum is selected by means of the multi-position switch 44. Ensuring that the nozzle 38 of the device 35 is situated in the connector 40, the cover 30 is closed to operate the pump 33. That is to say that by pressing the cover 3 for some seconds, the switch 29 start-up suction of the pump 33. The air is sucked from the chamber 4 and from the bag 26 and, following the arrows FI and F2 (Figure 8), exits through the opening 42. Consequently a vacuum is created in the chamber 4 and in the bag 26. When a satisfactory level of vacuum has been reached, a control signal is sent to the geared motor 8 which rotates the cam 16 which in turn makes the slide 18 to translate horizontally. During the stroke of the slide 18, the two pins 17 thereof, following the cam slots 30 of the resistance holding bar 19 cause raising of the resistance holding bar 19. The resistance holding bar 19 presses against the metal bar 22 and its coating 23, squeezing the two edges 25 of the bag 26. The resistance 28 of the resistance bar 19 causes heating of the edges 25 of the bag 26 and thus heat welding thereof. Rotation of the cam 16 also causes shifting of the air valve 13. Following this shifting the air valve 13 opens the opening 48 formed in the seat 2B of the base body 2 which separates the housing 7 from the chamber 4. Consequently, air is let into the chamber 4 from the air valve 13, in the direction of the arrows F3. This air let into the chamber 4 causes pressure on the outer surface of the bag 26, allowing the inner surfaces of the walls of the bag 26 to adhere to each other. Moreover the air let into the chamber 4 by the air valve 13 re-establishes the atmospheric pressure in the chamber 4 and thus allows the user to raise the cover 3 when the process of sealing the edges of the bag has been completed. Said process will be completed when the cam 16, on turning, gives impulse to the switch 15, which causes the start and end of the cycle. At this point the user can open the cover 3 and remove the package ready for storage. With reference to Figures 9 and 10, a possible suction pump for use in the machine 1 according to the invention will now be described. As can be seen in the figures, the pump 33 comprises two pistons 51 and 52, sliding counter to each other in respective cylindrical chambers 53, 54, so that while one sucks in air, the other expels the air previously sucked in, thus allowing continuous operation. The two pistons 51 and 52 are carried by respective connecting rods 55, 56, operated by respective cams 57 and 58, disposed in a pull-push fashion on a first common shaft 59. The shaft 59 carries a first gear wheel 60 meshing with a second gear wheel 61 with a smaller diameter, carried by a second shaft 62. The second shaft 62 carries a third gear wheel 63 with a larger diameter than the second gear wheel 61. The third gear wheel 63 meshes with a pinion 64 splined to the drive shaft 65 of the motor M. The suction holes 67 and 68 of the two cylinders 53 and 54 communicate with a duct 69 which is put into communication with the suction device 35 by means of the tube 36. The exhaust holes 70 and 71 of the two cylinders 53 and 54, on the other hand, are outwardly open (Figure 9). Alternatively, the suction duct 69 can be connected directly to the chamber 4 in which the vacuum has to be created. In this case a flow switch which can divert the output of the suction duct 69 toward the tube 36 when the device 35 is to be used to create a vacuum in rigid containers will be provided. The inside and outside walls of the basic body 2 and of the cover 3 of the machine 1 are preferably made of moulded thermoplastic resins. Special studies on the structural configuration of the parts of the machine 1 have made it possible to use plastic as the material, despite the chamber 4 of the machine 1 being subject to high vacuums during creation of the vacuum. The use of plastic has allowed a considerable saving on the materials and on the production process of the parts of the machine 1. Moreover the machine 1 is extremely light and easy to transport, therefore particularly suitable for domestic use. Numerous changes and modifications of detail known to a person skilled in the art can be made to the present embodiment of the invention, without departing from the scope of the invention set forth in the appended claims.

Claims: CLAIMS 1. A machine (1) for vacuum packing products in plastic bags (26) and rigid containers (37) comprising: - an airtight chamber (4), suited to receive a plastic bag (26) with the relative product (27), - sucking means for sucking air from said chamber (4), so as to create a vacuum inside said chamber and said bag (26) contained therein; - sealing means for sealing the edges (25) of the bag (26) after a vacuum has been created therein, - air input means (13) able to introduce air into said chamber (4) to remove the vacuum, - a suction device (35) connected to said suction means, for creation of a vacuum in rigid containers (37) provided with a valve (39). 2. A machine according to claim 1, characterized in that said chamber (4) is formed in a basic body or base (2) of the machine and is closed by a cover (3), sealing means (5) able to ensure an airtight seal being provided between the base and the cover. 3. A machine according to claim 2, characterized in that said sealing means comprise a gasket (5) made in a single piece, with a lip-shaped cross-section to compensate for errors in planarity between the cover and the base body (2). 4. A machine according to any one of the preceding claims, characterized in that said suction device (35) is connected to said sucking means by a flexible tube (36), to create a vacuum in said chamber (4). 5. A machine according to claim 4, characterized in that said flexible tube (36) is wound on a spring-loaded tube- winding device (12) disposed inside a housing (7) separated from said chamber (4) in which the vacuum is created. 6. A machine according to claim 4 or 5, characterized in that said suction device (35) is housed in a seat (34) of said machine (1) in which a connector (40, 41) communicating with said chamber (4) is provided. 7. A machine according to any one of the preceding claims, characterized in that said sucking means for sucking air from said chamber (4) comprise a pump (33), operated by a motor (M), which pump (33) by means of said suction device (35) sucks air from said chamber through at least one opening (42) made in said chamber (4). 8. A machine according to claim 7, characterized in that said pump (33) comprises two piston-cylinder assemblies (51 , 53; 52, 54) working in push-pull fashion. 9. A machine according to claim 7 or 8, characterized in that interposed between the motor (M) and the pump (33) is a reduction unit comprising a pinion (62) splined to the shaft (65) of the motor (M) which meshes with a first gear wheel (63) mounted on a first shaft (62) on which is mounted a second gear wheel (61) which meshes with a third gear wheel (60) mounted on a second shaft (59) which carries two cams (57, 58) for movement of the connecting rods (55, 56) of the pistons (51, 52). 10. A machine according to any one of the preceding claims, characterized in that said means for sealing the free edge (25) of the bag (26) comprise a welding bar (19) extending in crosswise direction of the edge of the bag (25) and means for moving said welding bar (19) able to move it with a reciprocating movement to press the edges (25) of said bag (26) against a counter bar (22), so as to achieve heat welding of the edges (25) ofthe bag (26). 11. A machine according to claim 10, characterized in that said welding bar (19) comprises an electrical resistance (28) and is mounted so as to be able to slide vertically on the basic body by means of vertical pins (17) which engage in respective bushings (20) formed in the basic body, said pins (17) providing the supply contacts of the electrical resistance. 12. A machine according to claim 10 or 11, characterized in that said counter bar (22) is mounted on a bridge structure (21) integral with the base body (2). 13. A machine according to any one of claims 10 to 12, characterized in that said means for moving said welding bar (19) comprise a geared motor (8) which rotates a cam (16) comprising a vertical pin (11) which engages in a transverse recess (9) of a slide (18) which provides at least one horizontal pin (46) that engages in at least one cam slot (30) formed on said welding bar (19). 14. A machine according to claim 13, characterized in that said air input means comprise an air valve (13) operated by said means for moving the welding bar (19) and mounted in a wall of the basic body (2) to introduce air into said chamber (4) from the outside. 15. A machine according to any one of the preceding claims, characterized in that said basic body (2) and said cover (3) are made of plastic material.

Inventors: MAINA GERMANO, MAINA, GERMANO
Applicants: MAINA GERMANO, MAINA, GERMANO
Application year: 2001
Main classification: B65B31
IPC codes: B65B31