According to the known art, for the packaging of products in a sealable film containing a modified and controlled atmosphere having characteristics which ensure the conservation of the packaged product, it is necessary to intervene in the phase of formation of the package around the product, before the package is closed, with first means for extracting the ambient air from the package, and if necessary with second means for introducing into the said package the controlled atmosphere which is then trapped in the package at the time of sealing. The machines which carry out this packaging process are relatively complex and are characterized by a low output per hour which is inevitably reflected in the selling price of the packaged product .

The invention proposes a new process for packaging products in a modified and controlled atmosphere, based essentially on the following concept of a solution. The forming and sealing of the package with heat-sealable and gas-tight film are carried out in a sealable main chamber provided with means which maintain in it a modified and controlled atmosphere necessary for the conservation of the products. It is evident that the packaging process is simplified considerably, since it is no longer necessary to use the means for forming the modified and controlled atmosphere selectively in the individual packages or in the individual packs. The packages are provided internally with the modified and controlled atmosphere necessary for the conservation of the product, since they

are formed and closed in an environment which is in a modified and controlled atmosphere. The product enters and leaves the main chamber by passing through corresponding entry and exit airlock chambers which are also sealable and are attached to corresponding apertures provided in the said main chamber, and are provided with corresponding doors for sealing with respect to the external environment and with respect to the said main chamber. When the outer sides of the entry and exit airlock chambers are opened, their inner sides are closed, in such a way that modified and controlled atmosphere does not issue from the main chamber. Before the inner doors which connect the airlock chambers to the main chamber are opened, the outer sides of these cham- bers are closed, and means may be provided to evacuate the ambient air from them and to refill them with modi¬ fied and controlled atmosphere.

The term "modified and controlled atmosphere", hereafter referred to for brevity as "modified atmosphere", signifies at least one of the following conditions : a) an atmosphere different from the external ambient atmosphere, consisting of one or more gases suitable for the conservation of the packaged product and having the same pressure as the external atmosphere; b) an atmosphere different from the external ambient atmosphere, consisting of one or more gases suitable for the conservation of the packaged product and having a pressure greater than the external atmospheric pressure ;

c) an atmosphere identical to the external ambient atmosphere but at a markedly lower pressure, typical of what is called "vacuum packaging" ; d) an atmosphere different from the external atmosphere, formed by one or more gases suitable for the conservation of the packaged product and having a pressu¬ re markedly lower than the external pressure, for use in what is called "vacuum packaging" .

According to the known art, when the modified atmosphere consists of a mixture of conservation gases, this mixture is generally prepared in advance according to the type of product to be packaged and is stored in a container from which it is taken in the quantity required for each cycle. It is evident that this complicates the preparation of the machine for the packaging of products of different types. To overcome this disadvantage, the invention provides that the modified atmosphere is preferably produced at the moment of use by the mixing of the various necessary primary gases, drawn from corresponding storage containers and mixed in the neces¬ sary quantity by mixing means controlled by a programma¬ ble processor, the whole being arranged so that the equipment in question can be rapidly adapted to the packaging of products of different types in a modified atmosphere.

The closest prior art known to applicant is repre¬ sented by document FR-A1 343 586.According to this document, there is disclosed a method and apparatus for the filling and closure of metallic drums with liquid substances in a sterilized environment. Apart from the

different scope, clearly the method and apparatus accor¬ ding to the said prior art document differ in a substan¬ tial manner from the method and equipement in accordance with the present invention, as it will appear evident from the following description.

Further characteristics of the invention and the advantages derived therefrom will be more clearly evident from the following description of some preferred embodi¬ ments of the invention, illustrated purely by way of example and without restriction in the figures on the attached sheets of drawings, in which:

Figs. 1 and 2 show schematically the equipment according to the invention and the corresponding operating process, in the version suitable for the packaging of products with a modified atmosphere and for

"vacuum" packages respectively,-

Fig. 3 is a schematic plan view from above and in partial section of an airlock chamber of the multiple-use type, which permits operation in fast and virtually continuous cycles;

Fig. 4 shows details of the solution shown in Figure 3, viewed through the section line IV-IV;

Fig. 5 is a side view, in partial section, of another airlock chamber of the multiple-use type; - Fig. 6 shows details of the solution shown in Figure 5, viewed through the section line VI-VI;

Figs. 7 and 8 show n greater detail possible embodiments of the equipment, with different types of machine for packaging with heat-sealable gas-tight film. In Figure 1 it will be seen that the equipment

according to the invention comprises a sealable main chamber 1, having a volume at least suitable for containing any known machine for the packaging of pro¬ ducts, as indicated previously by way of example. Accor- ding to the invention, the internal volume of the chamber 1 is saturated with the modified atmosphere necessary for the conservation of the products to be packaged, and for this purpose the chamber 1 is connected to at least one conduit 2 attached to means 3 for the controlled supply of the gas or various gases which are necessary for the formation of the said modified atmosphere, and which are obtained from the corresponding storage containers 4 , the said means 3 being controlled by a central processor 5, with a screen and keyboard, which by means of at least one suitable sensor 6 detects the composition and/or the quantity of the modified atmosphere in the chamber 1 and which by the preceding means 2, 3, 4 is made capable of maintaining in the said chamber 1 an atmosphere modified within predetermined parameters . The products P or P' enter and leave the main chamber 1 by passing through corresponding entry and exit airlock chambers 7, 8, which are sealable and are, for example, of the tunnel type, which communicate with the external environment through corresponding doors 107, 108, of the guillotine type for example, and are connected to corresponding operating actuators 9, 10. Similar doors 207, 208 with corresponding operating actuators 11, 12 are also provided in the area of the connection of the chambers 7, 8 to the main chamber 1 and the four actuators 9, 10, 11, 12 are connected to a

supply interface 100 controlled by the said central processor 5.

In a preferred embodiment of the invention, the airlock chambers 7 and 8 are connected at 113 and 114 to suction means 13, 14 controlled through a suitable interface 101 by the processor 5, and, in opposition to these means, conduits 15, 16, connected for example to part of the system 3, are attached to the said chambers for the introduction of the controlled atmosphere on command. It is to be understood that instead of the two suction means 13, 14 a single means may be provided, with means permitting its alternative connection to one or other of the said airlock chambers .

The equipment is completed by suitable conveying means, not shown in Figure 1, to introduce the product into the chamber 7, from there into the chamber 1 and then into the chamber 8, and finally to discharge it from the said equipment which operates as follows.

The processor 5 is used to determine the characteristics of the controlled atmosphere which is to be created and maintained in the main chamber 1, from which, at the start of each operation of the equipment, the ambient air is removed by means of at least one of the suction pumps 13, 14, with the temporary closure of the outer doors and opening of the inner doors 207, 208, after which the means 3, 4 are put into operation to introduce into the said main chamber the product conservation gases, in the specified quantity and at the specified pressure, the whole being carried out under the cor rol of the processor 5 and the sensor 6. The start of

a cycle requires the opening of the door 107 and the introduction of a product P or P' into the entry chamber 7, after which this door is closed, the means 13 come into operation to evacuate the ambient atmosphere contai- ned in the chamber 7, and the modified atmosphere is introduced into this chamber through the conduit 15. At this point the door 207 is opened to permit the passage of the product from the chamber 7 to the mam chamber 1 where, by means of the machine M operating therein and shown schematically as a reel of film, the said product is packaged and sealed with a heat-sealable gas-tight film, in such a way that part of the modified atmosphere which predominates chamber 1 and which will ensure the conservation of the product remains inside the package, without the operation of special means on the package as is required the known processes.

While the package containing the modified atmosphere is formed m the chamber 1, the means 14 are put into operation the closed chamber 8 to evacuate the ambient atmosphere, and the modified atmosphere is introduced into the sa d chamber through the conduit 16, so that, when the package is completed m the chamber 1, this can be transferred into the chamber 8 with the opening of the door 208 which s then re-closed. The packaged product MP or M' P' leaves the chamber 8 with the opening of the door 108 which is then immediately re-closed to enable this chamber to return to the condition suitable for receiving a subsequent product to be discharged, as stated previously Suitable means, not illustrated, may be provided to

recover the modified atmosphere present in the airlock chambers before these are connected to the external environment. Conversely, to simplify the equipment, the conduits 15 and 16 may be dispensed with, since the introduction of the modified atmosphere into the airlock chambers, after the ambient atmosphere has been evacuated from them, can be carried out by the main chamber 1, by the opening of the doors 207, 208, while a suitable quantity of modified atmosphere enters the said chamber 1 through the conduit 2.

The volumes of the airlock chambers 7, 8 are preferably as small as possible, to simplify the evacuation of the ambient atmosphere from them and their saturation with modified atmosphere. However, it is to be understood that the volumes of the airlock chambers may alternatively be such as to provide a phase of accumula¬ tion or collection of the products, in other words that they may be capable of containing more than one product each, so that the frequency of connection of these chambers to the exterior, with the previous conditioning of the chambers, is limited, and so that the packaging machine M is enabled to operate with greater efficiency. For this purpose, suitable means of accumulation and collection may also be provided inside the main chamber, immediately before and after the packaging machine operating in this chamber. These means have not been illustrated in the attached drawings, since they are immediately understandable to and easily constructed by those skilled in the art. The equipment shown in the variant in Figure 2 is

capable of producing "vacuum" packages and differs from the equipment in Figure 1 in the absence of the containers 4 for storing the gases for forming the modified atmosphere for conservation of the product, and of the corresponding programmable mixer 3, as well as in the absence of the conduits 2, 15, 16 for introducing the modified atmosphere into the main chamber 1 and into the airlock chambers 7, 8 which are now connected only to the suction means 13, 14 capable of creating the vacuum in these chambers before their connection to the chamber 1, which is also connected to a suction pump 30 controlled by the processor 5 through the interface 101, to maintain the exact level of vacuum in this chamber. The numbers 31 and 32 indicate solenoid valves which, on command, put the airlock chambers 7 and 8 into free communication with the ambient atmosphere, to pressurize them and to facili¬ tate the opening of the outer doors of these chambers. According to a variant embodiment of the solution shown in Figure 2, the pumps 13 and 14 may be dispensed with when the volumes of the airlock chambers 7, 8 are small, since the low variations of pressure created in the connection of these chambers to the main chamber can easily be controlled by the main pump 30. By the combina¬ tion of the solutions shown in Figures 1 and 2, it is possible, in a simple way which is immediately understan¬ dable to a person skilled in the art, to construct equipment capable of producing "vacuum" packages which contain, instead of residues of ambient atmosphere, residues of a modified atmosphere useful for the better conservation of the packaged product. In this case, at

least the mam chamber 1 and if necessary also the airlock chambers 7, 8 are connected to the corresponding conduits 2, 15, 16 which supply the conservation gas or gases obtained from the means 3, 4 mentioned previously with reference to Figure 1. The comments made with reference to Figure 1 concerning collection are also valid for the variant m Figure 2.

To obtain a faster operation of the whole equipment, each of the airlock chambers 7 and 8 may be formed by a plurality of chambers disposed one after the other in a closed loop and arranged in such a way that, while a first chamber is connected to the exterior to receive a product, at least a second and subsequent chamber contai¬ ning the product is m the phase of modification of the internal atmosphere, and a third and subsequent chamber, containing an atmosphere which is already modified, is in communication with the main chamber 1. At least a fourth closed airlock chamber is provided after the third of the said airlock chambers, between this and the first, so that when these chambers are moved by one step and change their relative positions, a product is loaded into and discharged from the mam chamber, while this chamber never communicates with the exterior. A first embodiment of this concept of a solution is shown m Figures 3 and 4 with references to the airlock chambers 7 which supply the products to the main chamber 1. The airlock chambers 7 are formed by the division into radial segments of a cylindrical hollow structure 33, in the form of a turret, which, by suitable means which are not illustrated, is made to rotate, on command, about its vertical axis, for

example in the direction indicated by the arrow 34. Each airlock chamber is provided with its own lower and upper walls 307 and side walls 407, is open towards the outside and carries at a short distance from its bottom a small horizontal conveyor 26 which is aligned initially with the external conveyor 27 to receive a product to be packaged and is subsequently aligned with the conveyor 20 of the chamber 1 to supply the product to the packaging machine. The conveyors 26 may be idle and may be made to rotate by the conveyor to which they are attached, for example by means of a coupling of the oscillating type, formed by friction or gear wheels 28 which, by means of an actuator which is not illustrated, are switched from the rest position shown in solid lines in Figure 4 to that shown in broken lines and vice versa. During the stepwise anti-clockwise rotation of the turret 33, the peri etric edges of the apertures of the airlock chambers 7, with the corresponding seals 29, interact with a fixed wall 35 which seals the said chambers, and the connec- tions 113 and 15, which enable the vacuum to be created in the said airlock chambers and the controlled atmosphe¬ re to be introduced if necessary, are attached to this wall . In the subsequent withdrawal from the main chamber 1, the airlock chambers 7 are closed, initially at least, by a fixed wall 36, which prevents connection of the chamber 1 to the exterior through the said chambers 7. It is evident that the modified atmosphere remaining in the airlock chambers leaving the chamber 1 can be usefully recovered with suitable means and introduced into the left-hand chambers which move towards the main chamber.

The airlock chambers 8 which discharge the packaged product from the main chamber 1 can be constructed according to the same solution shown in Figures 3 and 4. Figures 5 and 6 show another alternative embodiment to that shown in Figures 3 and 4, in which the airlock chambers 7 are formed by an apron or toothed belt conve¬ yor 37, running around a pair of toothed pulleys 38, 39 with horizontal and parallel axles, one of which is driven by a geared motor 40 which by means of the positi- ve transmission 41 drives a further apron or belt conve¬ yor 42 parallel to and beneath the said conveyor 37. The conveyor 37 carries and is integral with a plurality of identical and equally spaced transverse plates 43, which in the lower run of this conveyor touch the lower conve- yor 42 and define with it the airlock chambers 7 which are closed laterally by fixed walls 44, 45 to one of which are attached the conduits 113, 15 which create the vacuum and if necessary introduce the modified atmosphere into the chambers 7. In opposition to the conveyor 42 there is provided a fixed casing 46 with which the plates 43 interact to prevent the connection of the main chamber 1 to the exterior at least in the first portion of the path along which the airlock chambers move away from the said main chamber. The airlock chambers 8 can also be constructed according to this solution.

As shown in Figure 7, the machine M located in the main chamber 1 may be of the type which comprises at least one reel 17 of heat-sealable gas-tight film; idler means 18 to unwind the film from the said reel and to supply it to the subsequent means of engagement with a

correct longitudinal tension; means 19, called "cravat" means, which form the film into a tube by overlapping the longitudinal flaps, for example, in the lower part of the tube, a conveyor 20 which introduces the products P at the correct rate into the tube of film,- a powered presser 21 which interacts with the conveyor 20 to grip the tube of film and the product introduced into it and causes the longitudinal advance of this assembly; means 22 which carry out the longitudinal heat sealing SI (Fig. 1) of the overlapped longitudinal flaps of the tube of film; sealing and cutting means 23 which carry out on the tube of film a double transverse seal and an intermediate cut, to form the front and rear seals S2, S3 (Fig. 1) of the packages and to separate them from each other; a conveyor 24 which acts on the packaged product before and after the sealing phase and discharges them from the chamber 1 towards the exit chamber 8 where a corresponding dischar¬ ge conveyor 25 operates. A corresponding conveyor 26 operates in the entry chamber 7 to introduce the product to be packaged into the ma chamber 1.

The equipment shown in Figure 8 differs from that in Figure 7 in respect of the type of packaging machine M' located in the chamber 1, which comprises: two opposed reels of film 17-117, with corresponding unwinding means 18, 118; a conveyor 20 for supplying the product P' , after which there operates a sealing and cutting system 23 which carries out a double transverse seal and an intermediate cut on the joined films supplied from the reels 17, 117 for the formation of the front and rear seals S2-S3 (Fig. 1) on the tubular package of film which

wraps the product and for the separation of this package from the packaging film; two lateral sealing systems 27 (only one is visible in the figure) which close, by corresponding heat seals Sl-Sl' (Fig. 1) , the sides of the tubular package of film which, with the product, is made to advance by the presser 21 and by the conveyor 28 which will subsequently transfer the packaged product into the discharge chamber 8.

The chamber 1 and if necessary also the airlock chambers 7 and 8 are preferably made wholly or partially from transparent material which keeps the components inside these chambers visible, the chambers being provi¬ ded with hatches or covers or being made so that they can be dismantled, to permit, when necessary, simple and rapid access to the internal parts, for example for the insertion of the reels of film when they are exhausted and/or to facilitate the maintenance of the equipment.