Patent Description:
As known, vacuum packaging is a particular packaging technique which consists in storing substances, products and various objects, even clothing and garments, inside an envelope from which the air has been eliminated by means of suction.

The main and widespread use of vacuum packaging is in food storage because the majority of bacteria and micro-organisms cannot proliferate in the absence of air, and this allows the food, whether cooked or raw, to be stored longer.

Moreover, the food advantageously keeps its nutritional properties, flavor, aroma and also natural color unaltered under these storage conditions.

Among known food vacuum packaging and storage methods available and at hand today, particularly important is vacuum packaging under modified atmosphere, which consists in storing the food inside containers - usually transparent and heat-sealable bags made of flexible plastic material - into which a gas or a mixture of gases, for example nitrogen, carbon dioxide, oxygen and possibly others, is introduced after applying the vacuum.

The main advantage of vacuum storage under controlled atmosphere is ensuring longer storage of the food and organoleptic properties thereof, and it is particularly recommended for improving and lengthening the storage time of fresh pasta.

Moreover, vacuum storage in controlled atmosphere allows the quantity of chemical additives usually added to the products for extending the storage thereof, to be decreased.

For these reasons, use of vacuum storage in controlled atmosphere is increasingly widespread in the field of food packaging, and accordingly the request for vacuum packaging machines able to ensure this type of packaging is increasing too.

Vacuum packaging machines in controlled atmosphere on the market are the so-called chamber machines essentially comprising a base frame that supports:.

Operatively, the bag (or sachet), with the product to be packaged, is introduced into the tank while ensuring the nozzles are inserted in the bag itself through the open edge of the bag.

The open edge of the bag is therefore rested on the welding bar and the cover is lowered, thus creating a chamber communicating with the vacuum pump between the cover and the tank.

When the vacuum pump begins operating, air is extracted both from the chamber and from the bag until creating, in the chamber and in the bag, the degree of vacuum preselected by the user.

When the desired degree of vacuum is reached, the air extraction is stopped and a gas or a mixture of protective gases listed above is introduced into the bag through the nozzles to create, in the bag, a protective atmosphere that surrounds and protects the product.

At this point, the welding counter-bar and the underlying welding bar are mutually forced against each other to weld the edge of the bag comprised therebetween.

The atmospheric pressure is restored in the tank, the cover thereof is opened and the packaged bag is removed from the tank.

The chamber vacuum packaging machines now described have features of increased reliability and versatility, making them adapted to packaging a large variety of products.

Additionally, the ease of use and limited overall dimensions thereof make them particularly adapted to being used in the field of small- and medium-sized restaurants and gastronomy.

However, the chamber vacuum packaging machines now described are limited by having an intermittent cycle, and therefore they are not adapted to continuously package large quantities of multiple types of food.

In trying to overcome such a limitation, so-called "tilting cover" vacuum packaging machines in controlled atmosphere are provided and widespread on the market, these packaging machines essentially comprising two tanks for containing the food to be packaged and a single cover that tilts so as to alternatively cover one or the other tank, in each of which the vacuum packaging is alternately produced.

Practically, the two tanks are alongside each other and an operator loads the food to be packaged in a first tank, while the vacuum packaging process is being performed in the second tank, which is closed by the cover.

The packaged product is removed from the first tank at the end of packaging, and the cycle is repeated by introducing the new product to be packaged into the second tank.

Machines of this type allow the dead times to be reduced, and therefore production to be increased, however they are not capable of packaging in a continuous cycle and therefore they are not adapted for the industrial production of large quantities of products vacuum packed in modified atmosphere.

Indeed, for the industrial production of vacuum packed food belt vacuum packaging machines are indeed used which actually able to package food products of any kind in heat-sealable bags and in a substantially continuous cycle.

A machine of this type of the prior art is depicted in accompanying <FIG>, where it is indicated as a whole by A and where it is worth noting that it comprises a base frame C which in the upper part thereof defines a work surface D on which a conveyor belt E slides, on which the bags B containing the products to be vacuum packed observed in <FIG> are arranged.

Bag-guide conveyors L arranged at the sides of the conveyor belt E are fixed on the work surface D and serve to guide and support the edge of the bags B placed thereon.

The conveyor belt E transfers the preformed bags B with the products therein which the operators O arranged thereon from the loading area F up to the packaging area G, where there is a packaging chamber H.

When the packaging chamber H is arranged in contact with the conveyor belt E, the vacuum is created therein so as to define a vacuum chamber in which the bags B confined inside the packaging chamber H are subjected to the vacuum packaging process.

There is, on the work surface D and on the continuity of the bag-guide conveyors L, a welding bar M which is fixed to the work surface D and is arranged outside the lateral edges of the conveyor belt E, while a welding counter-bar (not shown in <FIG>), opposed to the welding bar M, is fixed inside the packaging chamber H.

Therefore, the welding bar M and the welding counter-bar are placed inside the packaging chamber H when it is lowered and facing the conveyor belt E.

A control panel N which the operators O access to control the packaging machine is fixed to the base frame C.

Operatively, with reference to <FIG>, the packaging provides for the bagged products to be arranged above the conveyor belt E with the edges of the preformed bags B arranged resting on the bag-guide conveyors L and for the subsequent advancement of the conveyor belt E to transfer the products bagged below the packaging chamber H.

Since the edges of the bags B are arranged resting on the bag-guide conveyors L and given that the welding bar M is arranged on the continuity of the same bag-guide conveyors L, when the conveyor belt E transfers the preformed bags B into the packaging area G at the packaging chamber H, the edge of the bags B is positioned on the welding bar M in position to be welded when the welding counter-bar is pushed against the welding bar M.

The packaging chamber H is then lowered and when the edge thereof adheres to the work surface D and conveyor belt E, the air is removed from the inner cavity thereof, which becomes the vacuum chamber in which the vacuum packaging occurs of the bags B with the products contained therein.

Therefore, the welding of the edge of the preformed bags B occurs by means of the welding bar M and the welding counter-bar which mutually sandwich such an edge of bag B comprised therebetween.

When the packaging chamber H is raised, the conveyor belt D is put into motion and the vacuum packed products are unloaded from the packaging machine A.

At the same time, further bagged products to be vacuum packed, which in the meantime were arranged in the loading area F, are transported to the height of chamber H for a new vacuum packaging cycle.

It is therefore understood from the above description that the belt vacuum packaging machines of the known type are capable of providing a substantially continuous automated production cycle and therefore are particularly adapted to industrial employment where large production is required.

Particularly, packaging machines of this type are used by fresh products production and packaging companies supplying small and large-scale distributors. However, these belt-type vacuum packaging machines of the known art present the recognized drawback of not being capable of providing vacuum packaging with subsequent introduction into the bags of gaseous substances to create a modified atmosphere therein which is useful for improved storage of the product contained in the bags.

On the other hand, packaging machines of this type are not present on the market and manufacturers offering belt-type vacuum packaging machines for packaging food products in modified atmosphere are not known to the Applicant.

This means that, in the current background art, products which are vacuum packed in modified atmosphere may be obtained only by using discontinuous systems, with undoubtedly much higher production costs (cost of the raw materials and labor employed also being equal) with respect to those encountered in the belt-type vacuum packaging systems of the prior art that however do not allow vacuum packaging in modified atmosphere.

Prior document published under <CIT> in any case shows a more evolved type of vacuum packaging machine which is more closely comparable with the belt-type vacuum packaging machine of the invention by providing a system for introducing gas into the bag where the vacuum was already created.

Thus, the present invention aims to overcome the above-described drawbacks of the known art.

In particular, it is main purpose of the invention to provide a belt-type vacuum packaging machine which allows packaging vacuum products in modified atmosphere in a continuous cycle.

It is another purpose of the current invention to indicate a belt-type vacuum packaging machine which allows a vacuum packed product in modified atmosphere to be obtained, the production cost of which is less than the production cost currently encountered for similar products which are necessarily produced in discontinuous cycle vacuum packaging machines.

Listed purposes are achieved by a belt-type vacuum packaging machine as in accompanying claim <NUM>, to which reference is made and which is not indicated in this section for the sake of brevity of description.

Further detailed technical features of the belt-type vacuum packaging machine of the invention are described in the dependent claims.

The aforesaid claims, hereinafter specifically and concretely defined, are intended an integral part of the present description.

Advantageously, the use of the packaging machine of the invention allows the continuous cycle packaging of vacuum packed products in modified atmosphere.

Again advantageously, the products that are vacuum packed by employing the packaging machine of the invention have increased preservation time with respect to equal products that are vacuum packed using belt vacuum packaging machines of the prior art.

Said purposes and advantages will be more apparent from the description that follows, related to a preferred embodiment of the belt-type vacuum packaging machine of the invention, given by way of indicative and non-limiting example, with the help of the accompanying drawings, in which:.

The belt-type vacuum packaging machine of the present invention is depicted in its entirety in <FIG>, in an exploded view in <FIG>, and in a partial view in <FIG>, where it is indicated as a whole by numeral <NUM>.

The belt vacuum packaging machine <NUM> of the invention, expressly intended to package products, generally food products, is also shown in a side view in <FIG>, while <FIG> show enlargements of parts thereof, and the remaining <FIG> show diagrammatic details thereof.

Finally, it should be noted that for descriptive brevity, the vacuum packaging machine <NUM> of the invention is simply indicated with the term "packaging machine <NUM>" in the continuation.

With reference to the drawings, it is worth noting that the packaging machine <NUM> comprises a base frame <NUM> which supports a work surface <NUM> which develops in length according to a longitudinal direction X.

A conveyor belt <NUM> developing along the same longitudinal direction X of the work surface <NUM> slidingly acts on the work surface <NUM> and is configured to transfer the products to be vacuum packed contained in preformed bags B from a loading area <NUM> to a packaging area <NUM> of the same work surface <NUM> (shown in <FIG>).

Advancements means (not shown in the drawings because they are in themselves known) of the conveyor belt <NUM> rotate at least one of two or more mutually parallel drums (or rollers) <NUM> revolvingly supported by the base frame <NUM> on which the conveyor belt <NUM> is wound in a loop.

A pair of mutually parallel lateral guides <NUM>, which develop according to the longitudinal direction X defined by the conveyor belt <NUM> and with respect to which they're symmetrically arranged on opposite sides, are fixed on the work surface <NUM>. The conveyor belt <NUM> is comprised between the lateral guides <NUM>, since the width of the conveyor belt <NUM> is less than the distance between the lateral guides <NUM>.

A packaging chamber <NUM>, which is arranged above the work surface <NUM> and is connected to the displacement means <NUM> which allow the approaching and distancing thereof with respect to the work surface <NUM> and with respect to the conveyor belt <NUM>, is present in the packaging area <NUM>.

Preferably, but not exclusively, the displacement means <NUM> comprise one or more fluid actuators <NUM> which are interposed between the base frame <NUM> and the packaging chamber <NUM>, but in another embodiment, the displacement means <NUM> could comprise electric motors which rotate ball screws supported by the base frame <NUM> and connected to the packaging chamber <NUM>.

In the described embodiment, the packaging chamber <NUM> has substantially parallelepiped shape and, as shown in <FIG>, the displacement means <NUM> comprise two fluid actuators <NUM>, one of which is shown in <FIG>, which are arranged at two adjacent corners of the packaging chamber <NUM>.

In another embodiment, not shown, there could also be a different number of fluid actuators positioned in a different manner.

When the packaging chamber <NUM> is moved close to the conveyor belt <NUM> and the perimetric edge 8a thereof comes into contact with the work surface <NUM> and with the upper surface of the conveyor belt <NUM> (as shown in <FIG> and <FIG>), a vacuum chamber <NUM> is defined in which the products contained in the preformed bags B are vacuum packed.

For this purpose, the packaging machine <NUM> comprises a vacuum production system <NUM>, which is depicted in detail in <FIG> showing that it comprises: a vacuum pump of the known type - not shown in the drawing because arranged outside the packaging machine <NUM> - which is connected to the vacuum valve <NUM>, intake manifolds <NUM> which are connected to the work surface <NUM> and which communicate with the vacuum chamber <NUM>, and intake ducts <NUM>, each of which connects the intake mouth <NUM> of the vacuum valve <NUM> with one of the intake manifolds <NUM>.

In the preferred but not exclusive embodiment of the packaging machine <NUM> under description, there are two intake manifolds <NUM> and two intake ducts <NUM>.

It is understood that this embodiment of the vacuum production system <NUM> is only one of the possible multiple embodiments which may be selected by a manufacturer.

The vacuum packaging machine <NUM> also comprises welding means <NUM> of the preformed bags B after the vacuum packaging which, as it can be noted in particular in <FIG> and <FIG>, comprise a pair of welding bars 12a fixed to the work surface <NUM> and a pair of welding counter-bars 12b, each opposed to a respective welding bar 12a, which are fixed to the packaging chamber <NUM>.

Finally, it is worth noting that the mutually overlapping welding bars 12a and welding counter-bars 12b are aligned according to two mutually parallel directions and arranged symmetrically and on opposite sides of the longitudinal direction X defined by the conveyor belt <NUM>.

More in detail, each welding counter-bar 12b is fixed inside the packaging chamber <NUM> and therefore, when such a packaging chamber <NUM> is lowered and defines the vacuum chamber <NUM>, also each welding bar 12a and the opposed welding counter-bar 12b are contained in the vacuum chamber <NUM>.

With regards in particular to the welding counter-bars 12b, one of them is depicted in <FIG> which shows that it is fixed to the canopy 8b of the packaging chamber <NUM> and protrudes and is aligned with the underlying welding bar 8a belonging to the work surface <NUM>.

Specifically, the welding counter-bar 12b and the welding bar 12a in <FIG> are arranged spaced apart from each other since they come into mutual contact only when bag B comprised therebetween is welded, as better explained below when the operating step of the packaging machine <NUM> is described.

Finally, there is an operating control panel <NUM> on the packaging machine <NUM> of the invention, the functions of which are described in greater detail below when the packaging machine <NUM> is described in operating step.

According to the invention, the packaging machine <NUM> comprises at least one injection system <NUM> of at least one inert gaseous substance into each preformed bag B received in the vacuum chamber <NUM>, wherein such an introduction occurs after the vacuum production system <NUM> has created the vacuum in each preformed bag B, and wherein the aforesaid injection system <NUM> comprises a plurality of injector nozzles <NUM> configured to be connected to the preformed bags B and be turned towards the inside of the same preformed bags B when the bags B are arranged on the conveyor belt <NUM>.

In particular, it is worth noting in <FIG> that the injection system <NUM> preferably comprises:.

As for the supply line <NUM> of the gaseous substance, <FIG> shows that it comprises a storage tank <NUM> which is connected to an external line (not depicted), from which it receives the gaseous mixture under pressure, and a delivery pipe <NUM> which connects the delivery mouth 27a of the storage tank <NUM> to the connecting means <NUM>.

In a preferred but non-binding manner, the connecting means <NUM> in turn comprise:.

As far as the injector nozzles <NUM> are concerned, the accompanying drawings, and particularly the detailed diagrammatic <FIG>, show that they belong to the conveyor belt <NUM> and each one is fixed in a through hole 4a made in the conveyor belt <NUM>.

Since integral with the conveyor belt <NUM>, the injector nozzles <NUM> and the preformed bags B they support therefore are movable together with the conveyor belt <NUM> itself, and this advantageously allows creating the vacuum and introducing the inert gaseous substance in atomized form into the different preformed bags B which are progressively to be packaged in a more continuous and quicker manner with respect to the known vacuum packaging machines, thus resulting in an improved hourly production for the vacuum packaging machine <NUM> of the invention with respect to the prior art, by a single operator who always remains stationary at the loading area <NUM> of the vacuum packaging machine <NUM>.

In this context, prior document <CIT> shows a system for creating the vacuum in an apparatus for vacuum packaging products contained in preformed bags (numeral <NUM>), each of which is temporarily and removably applied to an extractor member (numeral <NUM> and consisting of a protruding cylindrical duct) which is integral and fixed to, or incorporated in a conveyor belt (numeral <NUM>): exclusively and only the creation of the vacuum inside the preformed bag occurs through each extractor member, which significantly protrudes upwardly from the outer surface of the conveyor belt.

Therefore, if on one hand prior document <CIT> shows the presence of fixed or at most, rotating sprayer nozzles not coupled to the conveyor belt, and through which a gas (for example, carbon dioxide or a mixture thereof and other gaseous elements) is introduced into the preformed bag where the vacuum was already created, on the other hand prior document <CIT> shows simple protruding cylindrical ducts which are integral with the conveyor belt and which are never defined as injectors, through which the air is only extracted or sucked from the bags to create the vacuum therein.

As a result, starting from prior document <CIT> and prior document <CIT> also being available, the skilled person could not easily, immediately and unequivocally arrive at one of the significant technical concepts of the present invention, that is that the injection system <NUM> - by means of which at least one gaseous substance is introduced into each of the preformed bags B after the vacuum production system <NUM> has created the vacuum in each of such preformed bags B - in the vacuum packaging machine <NUM> herein claimed comprises a plurality of injector nozzles <NUM> belonging to the conveyor belt <NUM> which are configured to be connected to the preformed bags B and to be turned facing towards the inside of the latter when the preformed bags B are arranged on the conveyor belt <NUM> and used to spray atomized inert gas therein.

Moreover, each injector nozzle <NUM> inside the respective through hole 4a preferably is fixed by means of screw means 14a (which in particular are noted in the detail depicted in <FIG>) and which therefore provide a removable fastening of the injector nozzles <NUM> to the conveyor belt <NUM> to allow the possible replacement thereof.

Moreover, the injector nozzles <NUM> are aligned and spaced apart from each other one after the other along two straight directions X<NUM> which are spaced apart from and parallel to each other and are symmetrically arranged and parallel with respect to the longitudinal direction X defined by the conveyor belt <NUM>.

More in detail, it is worth noting that the injector nozzles <NUM> are fixed on two side bands <NUM> of the conveyor belt <NUM>, which are parallel to each other and are symmetrically arranged with respect to the longitudinal direction X defined by the conveyor belt <NUM>.

Additionally, each lateral band <NUM> is comprised between edge <NUM> delimiting the conveyor belt <NUM> and a plurality of slits <NUM> which are made in the conveyor belt <NUM> and are aligned and spaced apart one after the other along two straight directions X<NUM> which are spaced apart from, and parallel to each other and parallel and symmetrically arranged with respect to the longitudinal direction X defined by the conveyor belt <NUM>.

It is also worth noting that profile 19a of each slit <NUM> is configured to receive the through insertion of the welding means <NUM> which are arranged at the packaging area <NUM> and are aligned with the longitudinal alignment directions X<NUM> of the slits <NUM>, as shown in particular in <FIG>.

More specifically, as already noted above, <FIG> shows that each welding bar 12a is associated with the work surface <NUM> below the conveyor belt <NUM> and that each welding counter-bar 12b is opposed to the welding bar 12a and is arranged inside the packaging chamber <NUM>, it being fixed to and protruding from the canopy 8b of the packaging chamber <NUM> itself.

As also already mentioned, there are two welding bars <NUM> and two welding counter-bars 12b that are aligned parallel to the same longitudinal alignment directions X2 of the slits <NUM>.

<FIG> also shows that there is a pressure rod <NUM> protruding towards the injector nozzles <NUM> inside the packaging chamber <NUM>: the pressure rod <NUM> is fixed to canopy 8b of the packaging chamber <NUM>, is arranged alongside each welding counter-bar 12b and is provided at the end with a gasket <NUM>.

As it will be explained during the description of the operation of the vacuum packaging machine <NUM> of the current invention, when the packaging chamber <NUM> is lowered to create the vacuum chamber <NUM>, each pressure rod <NUM> advantageously and conveniently keeps the preformed bag B adhering to the injector nozzles <NUM> during the injection of the gaseous mixture, by means of gasket <NUM> with which it is provided.

When the packaging chamber <NUM> is lowered, it is worth noting in <FIG> that the perimetric edge 8a thereof comes into contact with the work surface <NUM> to define, together with the surface of the conveyor belt <NUM>, the vacuum chamber <NUM>.

The welding means <NUM>, the pressure rods <NUM> and the injector nozzles <NUM> which, as indicated, are supplied with the gaseous mixture directly from the collecting chamber <NUM> of the injection system <NUM> which is made in the thickness of the work surface <NUM>, are contained under these conditions inside the vacuum chamber <NUM>.

Substantially, it is the described constructive solution which provides applying the injector nozzles <NUM> to the conveyor belt <NUM> and supplying them inside the vacuum chamber <NUM> with the gaseous mixture originating from the supply line <NUM> passing through the work surface <NUM> which has allowed to provide the packaging machine <NUM> of the invention which, unlike the majority of conventional belt-type vacuum packaging machines of the prior art, allows a gaseous mixture providing the protective modified atmosphere of the product contained therein, to be injected into the preformed bags B.

Indeed, the passage of the gaseous mixture through the work surface <NUM> is allowed by the connecting means <NUM> that comprise the collecting chamber <NUM>, the inlet duct <NUM> and the outlet ducts <NUM>, which are made through the thickness of the work surface <NUM>.

Albeit not depicted, there necessarily is a control station provided with a dedicated software operatively connected to detection means (not shown or at least not marked with their own numeral below) that are configured to verify when the injector nozzles <NUM> are arranged at the respective outlet ducts <NUM> of the collecting chamber <NUM> and here, open the interception devices of the supply line <NUM> to supply the gaseous mixture to the injector nozzles <NUM> and inject it into the preformed or premade bags B.

Each welding bar 12a and each welding counter-bar 12b come into mutual contact and provide the welding of bag B comprised therebetween when:.

It is worth noting that in the embodiment of the packaging machine <NUM> described, when the packaging chamber <NUM> is lowered and defines the vacuum chamber <NUM>, the thrust means act on the welding bar 12a and force it against the above welding counter-bar 12b to weld the preformed bags B.

In another embodiment of the invention (not depicted), the thrust means could instead act on the welding counter-bar or on both.

Therefore, there will also be suitable sensor means, for example of the photocell or proximity type (not depicted in the following drawings and operatively connected to the control station), for determining the correct positioning and mutual alignment of the slits <NUM> with the respective welding bars 12a and welding counter-bars 12b prior to the lowering of the packaging chamber <NUM> and prior to the operation of the thrust means for welding the preformed bags B.

Operatively, the packaging in the vacuum packaging machine <NUM> of the current invention starts by arranging the preformed bags B with the product to be packaged therein on the conveyor belt <NUM>, as depicted in <FIG>.

Particularly, the edge of each preformed bag B in which there is the opening for inserting the product to be packaged is arranged above a slit <NUM> and the injector nozzles <NUM> are inserted through the opening thereof.

In the case described, there are two injector nozzles <NUM> for each preformed bag B, although it is to be understood that other embodiments of the invention, not shown in the following, may also have a different number, notably a greater number.

Then, the conveyor belt <NUM> transfers the preformed bags B from the loading area <NUM> to the packaging area <NUM> below the packaging chamber <NUM> which is lowered until the perimetric edge 8b thereof adheres to the work surface <NUM>, as noted in <FIG> and <FIG>.

Thus, the vacuum chamber <NUM> is formed, in which the pressure rods <NUM> ensure, by means of the gaskets <NUM> thereof, the adhesion of the preformed bags B to the injector nozzles <NUM> during the injection of the inert gaseous substance.

The vacuum production system <NUM> sucks air so as to create the vacuum inside the vacuum chamber <NUM> in addition to inside the preformed bags B contained therein and, once the vacuum is obtained in the preformed bags B, the supply system <NUM> (separate from the vacuum production system <NUM>) injects the gas mixture therein, through the supply nozzles <NUM>, thus creating the modified atmosphere which improves the protection of the vacuum product contained therein.

The successive sealing operation of the preformed bags B by means of welding, which is performed by means of the welding means <NUM>, completes the packaging of the products contained in the bags B themselves.

It's worth noting that in order for the welding to be more effectively performed, the welding bars 12a and corresponding welding counter-bars 12b, which are constructively opposite each other and are located within the periphery delimited by the vacuum chamber <NUM>, are arranged on opposite sides of and coincide with the perimetric edge 19a of the respective slits <NUM> in the conveyor belt <NUM>.

Indeed, only if these conditions occur will each welding bar 12a and the corresponding welding counter-bar 12b come into mutual contact by both passing through slit <NUM> when they are mutually moved by the respective thrust means.

In particular, as already mentioned, the thrust means force each welding bar 12a against the respective welding counter-bar 12b in the embodiment described.

Therefore, the operating panel <NUM> controls the packaging machine and controls the thrust means of the welding bars 12a and the welding counter-bars 12b to perform the welds, controls the correct positioning of the injector nozzles <NUM> with respect to the injection system of the gaseous substance, controls the correct positioning of the slits <NUM>, controls that the vacuum production system <NUM> and the supply system <NUM> of the gaseous substance to be injected into the bags are performed automatically and in a continuous cycle by the control station and dedicated software.

Moreover, it is worth noting that the described packaging machine <NUM> of the present invention is configured to simultaneously package four preformed bags B but it is apparent that this is only one of the possible configurations thereof, which may provide the simultaneous packaging of any number of preformed bags B.

In light of the description provided above, it is, therefore, understood that the belt-type vacuum packaging machine of the present invention achieves the purposes and reaches the advantages indicated above.

In particular, the invention achieves the preset object of making a belt-type vacuum packaging machine which allows products to be obtained which are vacuum packed in a modified atmosphere which cannot be obtained with the belt vacuum packaging machines available on the market.

It is reiterated that these results were achieved for the specific construction combination conceived and that provides for the injector nozzles <NUM> to be fixed in through holes 4a made in the conveyor belt <NUM> and to be supplied when they are inside the vacuum chamber <NUM> with the gaseous mixture to be injected into the preformed bags B which is conveyed by the injection system <NUM> through the work surface <NUM>.

The vacuum packaging machine of the invention also allows a vacuum packed product to be obtained which has improved storage conditions with respect to an equivalent product packaged by means of belt vacuum packaging machines of the known type.

Finally, it is apparent that several other variants may be made to the belt-type vacuum packaging machine in question, within the limited scope of the appended claims, just as it is apparent that any materials, shapes and sizes of the details shown may be used as needed in the practical implementation of the invention, and may be replaced by other technically equivalent elements.

Claim 1:
Belt-type vacuum packaging machine (<NUM>) for packaging products (P) contained in preformed bags (B), comprising:
- a base frame (<NUM>) which supports a work surface (<NUM>) which mainly develops along a longitudinal direction (X);
- a conveyor belt (<NUM>) which develops along said longitudinal direction (X) above said work surface (<NUM>) and cooperates with advancement means to transfer products (P) contained in preformed bags (B) from a loading area (<NUM>) to a packaging area (<NUM>);
- a packaging chamber (<NUM>) arranged in said packaging area (<NUM>) above said work surface (<NUM>) and said conveyor belt (<NUM>);
- displacement means (<NUM>) of said packaging chamber (<NUM>) with respect to said work surface (<NUM>) and said conveyor belt (<NUM>);
- a vacuum chamber (<NUM>) configured to receive said products (P) contained in said bags (B) to be vacuum packed, said vacuum chamber (<NUM>) being defined between the inside of said packaging chamber (<NUM>) and an upper surface of said conveyor belt (<NUM>) when a perimetric edge (8a) of said packaging chamber (<NUM>) is arranged in contact with said work surface (<NUM>) and said conveyor belt (<NUM>);
- at least one vacuum production system (<NUM>) that communicates with said vacuum chamber (<NUM>);
- welding means (<NUM>) of said preformed bags (B) adapted to be operated after vacuum packaging;
- at least one injection system (<NUM>) of at least one gaseous substance into each of said preformed bags (B) after said vacuum production system (<NUM>) has created the vacuum in each of said preformed bags (B), said injection system (<NUM>) comprising a plurality of injector nozzles (<NUM>) that are configured to be connected to said preformed bags (B) and be turned towards the inside of said preformed bags (B) when said preformed bags (B) are arranged on said conveyor belt (<NUM>),
characterized in that each of said injector nozzles (<NUM>) belongs to said conveyor belt (<NUM>) and is fixed in a through hole (4a) made in said conveyor belt (<NUM>).