WO1994022666A1

WO1994022666A1 - Process for pressing in particular, although not exclusively, grapes at a varying pressure, and machine for implementing said process

Info

Publication number: WO1994022666A1
Application number: PCT/EP1994/001045
Authority: WO
Inventors: Antonio Velo
Original assignee: Velo SpA
Current assignee: Velo SpA
Priority date: 1993-04-06
Filing date: 1994-03-31
Publication date: 1994-10-13
Anticipated expiration: 1995-10-06
Also published as: ITMI930684A0; ITMI930684A1; AU6565094A; IT1264785B1

Abstract

A process and a machine for pressing in particular, although not exclusively, grapes at a varying pressure is described, whereby the product to be pressed, which is made to pass between conveying means (10, 12) and pressing means (26, 11), is subjected, along the direction of feeding movement, to a varying pressure increasing in said direction. The feeding movement of the conveying means (10, 12) and hence feeding of the product are performed intermittently. The means (10, 12) for conveying the product to be pressed are inclined upwards in the direction of feeding of said product. In the bottom part of the loading hopper (14) of the machine there is provided a rotating drum (18) provided with radial vanes (20) which, in addition to exerting a pushing action for introducing the product between the two belts (10, 12), perform initial pressing with their bottom end edge which makes contact with the bottom wall of the loading hopper (14), through its essentially longitudinal slits (22). The radial vanes (20) of the drum (18) are preferably made of an elastically deformable material.

Description

"Process for pressing in particular, although not exclusively, grapes at a varying pressure, and machine for implementing said process"

The present invention relates to a process for pressing in particular, although not exclusively, grapes at a varying pressure, and to a machine for implementing said process.

More precisely, the machine forming the subject of the present invention is of the type known as a conveyor press in that it uses, for pressing the grapes, in its preferred embodiment, a pair of belts arranged at a suitable distance between which the grapes to be pressed are introduced. The belts are then fed forward and their movement, together with the pressing action which they exert on the grapes, causes simultaneously pressing thereof with production of the must and feeding of the marc towards the exit station and discharging thereof.

In the description which follows of the process and machine forming the subject of the present invention, specific reference will be made to the pressing of grapes, but this must not be regarded as limiting since both the abovementioned process and machine may advantageously be used for pressing plant products in general, such as the pressing of olives, seeds and other similar products as well as fruit.

The conventional machines of this type have a series of drawbacks, one of the major ones being the fact that the pressing action exerted by the belts is substantially constant along the entire travel path of the grapes between the latter, so that generally the pressing efficiency is substantially limited in that the marc discharged by the machine is still "rich", i.e. it is still possible for must to be extracted from it. Consequently, this marc must be passed again at least once between the belts, resulting in long operating times which negatively affect the cost of the product to be pressed, increasing it considerably.

A further disadvantage, which is closely linked to the preceding one, lies in the fact that the successive pressing operation or operations force the operator to collect the marc produced by the machine in a special container and to take it back round to the loading zone of the machine, this operation, in addition to being extremely inconvenient, also further prolonging the operating times with the consequent negative consequences mentioned above.

A further drawback of conventional machines consists in the fact that the must obtained from the various pressings must be collected in different containers. In fact the must from the first pressing is of the best quality, a quality which gradually decreases with the successive pressings since the must becomes gradually less and less "pure", containing also the liquid product resulting from pressing of the grape skins.

Another not insignificant drawback of the known machines arises from the fact that a continuous feeding movement is imparted to the aforementioned pressing belts, so that it is difficult to determine the optimum value for the speed of the aforementioned feeding movement which would enable one to obtain in particular the entire quantity of best-quality must from the first pressing and generally must of the same quality from the successive pressing or pressings.

The aforementioned drawback is also clearly of particular significance since the value of the feed speed of the belts must be determined in accordance with the type of grape to be pressed.

A process for pressing grapes at a varying pressure, which enables all the drawbacks of the prior art as described above to be eliminated, has now been devised and represents the subject of the present invention.

A machine for pressing grapes at a varying pressure also forms the subject of the present invention, said machine being more particularly a machine of the type known as a belt press, whose novel and original design enables the drawbacks of the machines of the known type to be overcome. The characteristic features as well as the advantages of the process and the machine which form the subject of the present invention will emerge more clearly from the following detailed description of a preferred non-limiting embodiment thereof and of constructional variants, a description which will be provided with reference to the accompanying drawings, of which:

Figure 1 is a schematic overall side view of the machine according to the present invention; Figure 2 is a schematic perspective view of a part of the machine according to the invention;

Figure 3 is a schematic cross-sectional view of the machine according to the invention;

Figure 4 is a partial schematic view on a larger scale illustrating the conveying means and the means which support them and permit the •sliding movement thereof;

Figure 5 is a schematic perspective view illustrating the entry station of the machine according to the invention;

Figure 6 is a partial cross-sectional schematic view of a constructional variant of the machine according to the invention;

Figure 7 is a view similar to Figure 1 showing a further constructional variant of the machine according to the present invention;

Figure 8 is an overall schematic side view of a further constructional variant of the machine according to the invention;

Figure 9 is a schematic perspective view of a part of said further constructional variant according to Figure 8.

With reference to the accompanying figures, the process according to the present invention, consisting essentially in passing the grapes to be pressed between conveying means and pressing means located opposite thereto, is characterized in that a pressing action, the intensity of which increases in the direction of feeding of the grapes, is imparted to the said pressing means at predetermined distances along the grape feeding path. In this way, said pressing means subjected to said varying pressure are moved closer and closer towards the associated conveying means in the direction of feeding of the grapes.

The above feature proves to be particularly advantageous since the must obtained from pressing at a varying pressure as described above is of different quality from the beginning to the end of the aforementioned pressing operation and in particular the must obtained at the beginning will be of the best quality, while the musts obtained during the successive pressing operations performed at greater pressure will be of an inferior quality compared to the preceding one, being definable - using a definition known in the art - as second choice, third choice, and so on.

The process according to the invention is also characterized in that the an intermittent feeding movement is imparted to the aforementioned conveying means.

With reference first of all to Figures 1 to 3, the machine according to the invention, in its preferred embodiment, comprises an upper conveyor belt 10 and a lower conveyor belt 12 which are essentially parallel with each other. The lower conveyor belt 12 has a length greater than that of the upper conveyor belt 10, since its front end, i.e. the end arranged on the side where the grapes to be pressed are introduced, extends beyond the front end of the upper belt 12 and is arranged in a substantially middle transverse position underneath a loading hopper 14 for the grapes.

At the bottom end of the hopper 14, and inside the latter, there are provided means for pushing the grapes, indicated in their entirety by 16, which are designed to cause introduction of the grapes between the belts 10 and 12 as indicated by the arrow F in Figure 1.

In the embodiment considered the pushing means 16 consist of a cylinder or drum 18 which is supported in a freely rotatable manner at its ends by the side walls of the hopper 14, one of the said ends being connected in a known manner, not shown, to a drive motor, also not shown, designed to impart to the drum 18 the necessary rotation which occurs in the direction of the arrow G of Figure 1.

The drum is provided on its contour with a plurality of radial vanes 20 made of elastically deformable material such as rubber or the like. The function of the vanes 20 is twofold, as will be explained below.

In particular the vanes 20 perform a first important function of dividing up and distributing the product to be pressed in such a way that the belts 10 and 12 are always loaded with the same quantity of product and the latter is uniformly ditributed over the entire width of the belts between which it is pushed by the aforementioned vanes 20.

Substantially the drum 18 with its radial vanes 20 may be regarded as a displacement pump which imparts to the product to be pressed the force necessary for feeding the pressing belts.

Furthermore the assembly consisting of the loading hopper 14 and drum 18 with the vanes 20 also performs, as will become clearer below, the important function of a "lung". In fact, according to one of the main features of the process and the machine forming the subject of the present invention, the pressing belts are activated intermittently so that the loading hopper and the feed drum must absorb the excess quantity resulting from continuous loading thereof when the conveyor belts are stopped.

According to a further particularly advantageous feature of the present invention, as can be seen in particular in Figure 5, the drum 18 with its radial vanes 20 performs a second important function consisting in the preliminary pressing of the grapes fed into the hopper 14, via a series of slits 22 formed in the bottom portion of the wall of the hopper 14 through which the pressed must passes, falling into an underlying collection tray described below.

In order to improve the efficiency of conveying of the grapes between the two belts 10, 12 and the abovementioned pressing operation effected via the slits 22, the width of the vanes 20 is slightly greater than the distance between the contour of the drum 18 and said portion of the bottom wall of the hopper 14. The end edge of the vanes 20 which comes into contact with said bottom portion of the wall of the hopper 22 will therefore undergo slight deformation which favours both conveying of the grapes and preliminary pressing thereof.

Along the path travelled by the end edge of the vanes 20 when the drum 18 is rotated, there is arranged, substantially in the region of the end where the grapes are introduced between the two belts and more precisely substantially at the same height as the corresponding end of the upper belt, a cylinder 24 mounted on the side walls of the hopper 14 in a freely rotatable manner. This cylinder 24 prevents the grapes from passing back above the drum 18 so that the entire quantity of grapes fed into the hopper 14 is conveyed between the two belts 10, 12. This feature is also made possible on account of the elasticity of the radial vanes 20 which, when they come into contact with the cylinder 24 are deformed so as to be able to extend beyond said cylinder, preventing transportation of the grapes above the drum 18.

As can be seen from Figures 1 to 4, with the upper conveyor belt 10 there are associated pressing means arranged at a predetermined distance from one another, each of which is designed to impart to said belt 10 a pressure of predetermined value so as to cause the calibrated movement of the belt 10 towards the underlying lower belt 12.

In the example of embodiment considered, said pressing means are four in number and situated equidistant along the length of the belt 10 and each consist of an actuating piston, the cylinder of which is mounted on the fixed frame of the machine, while the rod acts on associated means rigidly fixed to the belt 10 as explained below.

A description will be provided, with particular reference to Figures 1 to 3, of only one of the said pressing means, each denoted in its entirety by 26, since the remaining three are substantially identical.

Each pressing means 26 comprises a cylinder 28, the upper end of which is hinged with a cross-beam 30 of a portal frame 32, the uprights 34 of which extend laterally with respect to the conveyor belts 10 and 12 and are connected in a known manner, not shown, to the fixed frame of the machine.

The rod 36 of the piston of the cylinder 28 is pivotably hinged on a lug 38 of a cross-beam 40 which extends in a substantially horizontal manner above the upper conveyor belt 10.

It is obvious that, in order to ensure that the thrusting action of the pressing means 26 is equally distributed, for each portal frame 32, and more precisely for each cross-beam 40, two cylinders 28 are provided, each of which are connected to one of the ends of the aforementioned cross-beam 40.

With each end of the cross-beam 40 and the upper conveyor belt 10 there is associated and rigidly fixed thereto in any known manner, a shaped wall, denoted in its entirety by 42, which is preferably, although not necessarily made of metal.

The wall 42 is substantially S-shaped and its upper hoirxontal side 44 is rigidly fixed to the upper end edge of the cross-beam 40.

The lower horizontal side 46 of the wall 42, when the piston 28 is not activated, is situated substantially at the same height as the upper side of the lower conveyor belt 12.

The vertical side 48 of the wall 42 extends in a substantially perpendicular manner with respect to the plane of the upper conveyor belt 10 and, on its inner side facing said conveyor belt 10, there is fixed a pair of substantially longitudinal plates 50 which have substantially the same width as the vertical side 48 of the wall 42. This width is of a value such that, overall, said walls 42 form, in their entirety, a continuous side wall with respect to said conveyor belts 10 and 12 which prevents the product being pressed from escaping from the latter. More precisely, the first wall 42 associated with the first pressing means 26 is of a width such that it extends from the entry end of the conveyor belt 10 as far as the middle zone between the first and second pressing means 26, while the remaining walls 42 are of a width substantially equal to the distance between the middle zone between one pressing means 26 and the next one.

As can be seen in particular from Figures 2 and 4, between the upper and lower portions of the upper belt 10, there are arranged means for bracing said belt designed to prevent the aforementioned portions from moving closer to one another when the piston 28 is activated, thus exerting a thrusting action on the conveyor belt 10.

In the example of embodiment considered, said bracing means consist of preferably metal profiles 52 which, in cross-section, are substantially in the shape of a U, the parallel sides of which make contact with the conveyor belt 10 via suitable spacers described below.

Each of the bracing profiles 52 has a width substantially equal to or, more precisely, greater than that of the belt 10 and its ends are fixed in any known manner, not shown, to the inner face of the wall 42. Moreover, the bracing profiles 52 are arranged so as to be equidistant and facing in the same direction along the entire length of the belt 10.

The spacing means referred to above, which are more clearly visible in Figures 2 and 4, comprise a metal plate 54 similar to the metal end plate 50 integral with the inner surface of the wall 42, which, like the metal plate 50, is rigidly fixed in any known manner, not shown, to the outer surface of one of the parallel sides of the profile 52.

On the side of each of the plates 54 opposite to that fixed to the bracing profile 52 there is rigidly fixed in any known manner an elongated plate-shaped element 56, preferably made of plastic material, on which a corresponding portion of the belt 10 rests and travels. In this way the various spacers 54, 56 perform the dual function of keeping the belt 10 separate from the bracing profiles 52 and of facilitating the sliding travel of said belt with respect to said profiles.

The upper conveyor belt 10, as well as the lower conveyor belt 12, are formed by means of a plurality of metal links 10a, 12a pivotably hinged together by means of hinges 58 which allow both movement of the belt by means of the pressing means 26 and feeding on the toothed end wheels denoted by 60. Of these said toothed wheels 60 obviously, for each of the belts 10 and 12, one is a driving wheel connected to a suitable drive motor, while the other one is keyed onto a shaft mounted in a freely rotatable manner on the machine frame.

So as to allow the must to fall from the conveyor belts 10, 12 into the underlying trays, between the links 10a, 12a of the said belts there may exist a limited degree of play which allows the must to pass through or the links may be provided with holes so as to facilitate further said through-flow.

As can be seen from Figures 2 and 4, a preferably metal profile 62 with a substantially C-shaped cross-section is applied and rigidly fixed to the ends of the lower conveyor belt 12, in the region of each of the walls 42. The width of each profile 62 is essentially equivalent to that of the wall 42 associated therewith and said profile 62 and said wall 42 may freely slide with respect to each other, whilst remaining at the same time always in contact with each other in order to prevent the product being pressed from escaping from the two belts.

The lower conveyor belt 12, at its ends, is in sliding contact with the parallel sides of the profile 62 by means of the arrangement, in between, of a plate-shaped element 64 similar to the plate-shaped elements 56 of the spacers described above with reference to the first conveyor belt 10.

Also from the aforementioned cross-section it can be noted that a preferably metal plate 66 is associated with and fixed to each plate-shaped element 64, said plate also acting as a spacer element for the lower conveyor belt 12 with respect to the bracing profiles 52.

Also with regard to the design of the lower conveyor belts 12, it is not described in detail since it is also substantially identical to that of the upper conveyor belt 10.

From the above description and with particular reference now to Figures 1 and 2, when the machine is started up to perform pressing, the various pressing cylinders 28 are activated simultaneously by a centralized control unit, not shown, at a pressure which varies, in particular increases from one pressure cylinder 28 to the next one in the direction of feeding of the product to be pressed, i.e. from the entry point to the exit point of the two conveyors 10 and 12.

As can be seen in particular from Figure 2 for one of said pressing cylinders 28, the downward movement of the rod 36 causes a corresponding downward movement of the wall 42 and hence of the belt portion 10 integral therewith. The two starting and finishing positions are shown, respectively, by a continuous and broken line and it can also be seen that the lower end of the wall 42 slides on the outer side of the profile 62.

The same applies to the other walls 42, but at varying pressures as explained above.

Thus the conveyor belt 10 assumes a configuration in which each of its portions between one pressure means 26 and the next is inclined with respect to the preceding one, as is the case of the first portion with respect to the entry end. Said inclination is directed downwards so that, overall, the first conveyor belt 10 converges towards the underlying lower conveyor belt 12.

In this way pressing of the grapes will initially be performed at the minimum pressing pressure of the machine, making it possible to obtain a top-quality must resulting from pressing of the grape pulp alone, while the following pressing operations will increasingly involve the grape skins as well, so that the must obtained will be of a correspondingly inferior quality.

According to a further characteristic feature of the present invention, the feeding movement of the conveyor belts 10, 12 is not continuous, but intermittent and for this purpose provision is made for suitable programming means of the known type, not shown, designed to activate and deactivate at predetermined time intervals the associated drive motors for effecting the feeding movement of said belts.

From the above description it is obvious that owing to the intermittent feeding movement of the conveyor belts 10 and 12 and variation of the pressure exerted on the latter along the travel path of the product being pressed, the machine according to the present invention offers both the advantages of belt presses of the known type as well as those of presses of the pneumatic, for example membrane type, so that the machine in question is particularly advantageous both from the point of view of performance and as regards the quality of the product obtained.

According to a further characteristic feature of the machine according to the present invention, as can be seen from Figure 1, the conveyor belts 10, 12 are inclined upwards in the direction of feeding of the product to be pressed and this configuration offers several advantages, the most notable of which are as follows:

- loading of the loading hopper 14 is performed in a low position so that it is not required to raise the product to be introduced into said hopper, along with the obvious savings in energy;

- discharging of the pressed marc is performed at a relatively high height, thus allowing the use of particularly spacious collection tanks, inside which the discharged product is stored;

- increased possibility for drainage in particular in the front part of the machine;

- possibility for the machine to function also as a continuous press, i.e. with the continuous feeding of the belts, whilst obviously keeping the pressure of the pressing cylinders varied along the various sections of the belts, with an obvious reduction in the times during which the product is subjected to pressure.

Underneath the conveyor belts 10 and 12, the machine according to the present invention, as can be seen in particular from Figure 1, comprises a plurality of trays for colleccing the must which, in the example of embodiment considered, are three in number, each being associated with one of the pressure means 26 so that each of the trays, denoted by 68, 70 and 72 respectively, receive must of the same quality. Each of the trays 68, 70 and 72 is provided with its own outlet means, 74, 76 and 78 respectively, so that, underneath each of the trays 68, 70 and 72, there is arranged a suitable container designed to be filled with must.

As can be noted in particular from the overall side view of the machine according to the present invention, the collection trays 68, 70 and 72 are inclined and more precisely inclined downwards in the opposite direction to the direction of feeding of the product to be pressed, as indicated by the arrows S in the aforementioned figure, so that the must collected in said trays is conveyed through the simple action of gravity towards the outlet ducts 74, 76 and 78.

According to a further particularly advantageous feature of the machine according to the present invention, the varying pressure, in particular the increase of the same from the entry point to the exit point of the conveyor belts 10, 12, means that it is possible to obtain a pressed product which has a gradually decreasing moisture content as it passes through the press, so that, upon discharging, the product obtained is practically dry and hence the marc may be regarded as fully pressed.

According to a variation of embodiment which is also particularly advantageous, as can be seen from the partial view of Figure 6, instead of associating the pressure means 26 with the upper conveyor belt 10, said pressure means 26 may be associated instead with the lower conveyor belt 12, whilst obtaining practically the same operating modes and performance for the machine. In this case the pressing means 26 are arranged so as to cause raising of the various portions of the lower belt 12, i.e. moving of the latter towards the upper conveyor belt 10, assuming in this case a configuration where each portion is inclined upwards with respect to the preceding portion.

In this constructional variant the pressing means 26 are no longer connected to the cross-beam 40 associated with the upper conveyor belt 10; instead said pressing means 26 are incorporated in the uprights 34 of the portal structure 32 which is modified as explained below.

Each of the uprights 34 is formed by two parts, the upper part of which, indicated by 34a, is integral, at its top end, with the cross-beam 30 of the portal structure 32. Said portion 34a is connected to the lower portion 34b of the upright 34 via said pressing means 26, and more precisely the cylinder 28 of said pressing means is pivotably hinged with the bottom end of the upper portion 34a, while the rod of the piston 28 is connected to the top end of lower portion 34b.

The bottom ends of the lower portions 34b of the uprights 34 of each portal 32 are connected by a cross-beam 80 to which there is fixed, on each side of the lower conveyor belt 12, the bottom horizontal side 46 of the wall 42 which is also present in this embodiment as in the preceding one, but in this case being associated with the lower conveyor belt 12 instead of the upper conveyor belt 10. The configuration of the parts is the same as that of the preceding embodiment.

From the above description it can be seen that operation of the pressing means 26, i.e. retraction of the rod 36 of the pistons 28, causes raising of the cross-beam 80 from the position shown in continuous lines to the position shown in broken lines and this displacement results in a consequent displacement upwards of the wall 42 and hence of the lower conveyor belt 12 which is therefore moved towards the upper conveyor belt 10.

In this case also the wall 42 moves in contact with and with the possibility of sliding with respect to the C-shaped profile 62 now integral with the upper conveyor belt 10. The same observations made above with regard to the previously described embodiment also apply to this configuration. It should be emphasized that, in the variation of embodiment, the conveyor belt 10 and more particularly the C-shaped profile 62 is mounted in a fixed position on support means, not shown, which connect it to the fixed frame of the machine, in particular to the upper portion 34a of the uprights 34 of the portal structure 32.

It is obvious that, also in the constructional variant now briefly described, the various pressing means 26 are operated at a pressure which increases in the direction of feeding of the product, again with the aim of subjecting the latter to an increasing pressure from the entry point to the exit point of the machine, resulting in the same advantages mentioned above for the first embodiment.

It should also be noted that, in both embodiments described above, both the upper conveyor belt 10 and the lower conveyor belt 12 consist of a single belt, while they may be advantageously formed of several separate belts, each corresponding to a portion of the continuous belt with which a pressing means 26 is associated. In this case, obviously, the various belts are linked together via drive means or the like so as to operate in a synchronized manner and avoid discontinuities in the conveying of the material to be pressed.

With reference now to Figure 7, which is a similar view of the machine illustrated in Figure 1 , a brief description is provided of a further constructional variant of the machine according to the invention.

In the aforementioned figure the same elements as in Figure 1 are indicated by the same reference numbers.

The abovementioned variant consists essentially in the fact that the conveyor belt with which the pressing means 26 are associated is articulated in the region of the portion to which said means are applied in order to give the upper belt the desired broken-line configuration as referred to above.

With reference to Figure 7 it can be seen that said hinged articulations consist, for each pressing means 26, of a cylinder 82 arranged transversely with respect to the direction of the feeding movement of the belt which engages with the lower section of the belt itself and is mounted in a freely rotatable manner at its ends on support means connected to the end of the rod 36 of the piston 28. When the rod 36 is lowered, the cylinder 82 causes the belt portion with which it engages to descend by a corresponding amount, causing simultaneously a downwards inclination of the belt part preceding said roller 82. This configuration is made possible by exploiting the necessary play already existing between the links which form the belt and which compensate for the variations in length due to said downwards inclination.

It is obvious moreover that the extent of the downward movement of each roller 82 will increase in the direction of the feeding movement of the belt 10.

With reference now to Figures 8 and 9, a brief description is provided of a further variant of the machine according to the present invention.

In this variant only one belt is provided for conveying the product to be pressed instead of the two belts of the preceding embodiments, while at the same time the pressing or crushing means consist of essentially flat elements with which there are associated thrusting means which act on said flat elements so that they press with a predetermined pressure against the product to be pressed.

Said flat elements are separate and independent of one another.

It should be emphasized that, even if this variant differs partly from the preceding ones, it has many constructional features in common with them. For this reason, solely for the sake of comprehension, the same reference numbers shall be used for the same parts and components common to the two machines. These parts and components will not be described in detail now since they have already been mentioned with reference to Figures 1 to 5.

From Figures 8 and 9 it can be seen that the machine comprises a conveyor belt 12 on which the product to be pressed is fed from a loading hopper 14 having, for example, the same design as that described above, so that now a detailed description thereof is also omitted.

In this case also the conveyor belt 12 is inclined upwards in the direction of feeding of the product being conveyed by it, indicated by the arrow F in Figure 8, and its feeding movement is intermittent.

The conveyor belt 12 has associated with it pressing means arranged at a predetermined distance from one another which, in the example of embodiment considered, are four in number and situated equidistant along the length of the belt 12 and each consist of an actuating piston, the cylinder of which is mounted on the fixed frame of the machine, while the rod acts on an actual pressing means, denoted in its entirety by 11, consisting of a substantially flat body or element which will be described in detail below.

The pressing means, each denoted in their entirety by 26, are substantially the same as those described previously with reference to Figure 2, so that a description of them is not provided.

Still with reference to Figures 8 and 9, it can be seen that each of the actual pressing means 11 consists of a flat body or element which extends longitudinally above the conveyor belt 12, the lateral edges of which are fixed in any known manner, not shown, to the inner faces of the walls 42.

Bracing elements 13 consisting of preferably metal profiles with a C-shaped cross-section are fixed above the pressing body or element 11, at least in the region of its ends. The bracing profiles 13 are also preferably fixed, at their ends, to the inner face of the walls 42 so as to make the pressing means 11 particularly robust and strong.

In the example of embodiment considered, each of the said pressing means 11 consists of a plurality of preferably metal slats 15 which are of the same length and are rigidly fixed to one another in any known manner, not shown, so as to form a flat one-piece body.

The slats 15 may make contact with each other or may be slightly separated from one another with suitable spacers arranged in between. This latter solution offers the advantage of increasing the area over which the must is able to escape or drain away since most of the must is able to flow over the said element and fall back into the underlying collection trays from its contour.

As stated above, the one-piece body 11 consisting of slats 15 is one of the possible embodiments of the pressing means of the machine according to the invention. It is obvious, however, that these means may be constructed differently without departing from the scope of protection of the present invention. For example, they may be formed by a bored or solid-wall plate, in a meshwork, preferably although not necessarily made of metal or the like. The pressing means 11 are separate and independent of one another so that the degree of pressure which these means exert on the product to be pressed may be regulated and graduated individually, among other things according to the type of product to be processed.

Obviously in this case also, the conveyor belt 12, instead of consisting of a single belt, may advantageously be formed by several separate belts each corresponding to a portion of the continuous belt with which a pressing means 26 is associated.

The above description clearly highlights the advantages resulting from the process and machine forming the subject of the present invention, the major ones of which have already been referred to above.

It is obvious, finally, that structurally and conceptually equivalent variations and/or modifications may be made to the process and machine forming the subject of the present invention, without departing from the scope of protection thereof.

Claims

1. Process for pressing plant products, consisting essentially in passing the product to be pressed between means for conveying the same from the entry point where it is loaded to the exit point where the pressed product is discharged, and means for pressing the product, characterized in that the product to be pressed, during its feeding movement between said conveying means and said pressing means, is subjected to a varying pressure which increases in the direction of feeding of said product.

2. Process according to Claim 1, characterized in that the feeding movement of said conveying means is performed intermittently.

3. Machine for pressing plant products, characterized in that said conveying means comprise at least one conveyor belt (10, 12) having associated with it said pressing means (26) designed to exert on the product arranged thereon a pressure increasing in the direction of feeding of said product.

4. Machine according to Claim 3, characterized in that the conveying means comprise a pair of conveyor belts, one upper 10 and one lower 12, between which the product to be pressed is passed, said conveyor belts 10, 12 being connected to drive means designed to cause the feeding movement thereof essentially in synchronism with each other, there being associated with at least one of the conveyor belts 10, 12 pressing means 26 arranged at a predetermined distance from one another and designed to exert on said at least one of the two conveyor belts 10, 12 a thrusting action in the direction of the other belt arranged opposite, said thrusting action having a value which increases in the direction of feeding of the product to be pressed.

5. Machine according to Claim 4, characterized in that the drive means for the feeding movement of the upper and lower conveyor belts 10, 12 are connected to timing means designed to effect intermittent feeding of said conveyor belts 10, 12.

6. Machine according to Claim 4, characterized in that each of said pressing means 26 comprises a pair of pistons 28 arranged substantially in the region of the lateral edges of the upper conveyor belt 10, the cylinder of which is connected to an upper cross-beam 30 of a portal frame 32 while the end of their rod 36 is connected to a cross-beam 40 integral with a portion 44 of a side wall 42 which has fixed, to its inner face, the lateral edge of means for supporting and bracing the conveyor belts 10, 12.

7. Machine according to Claim 4, characterized in that said means for supporting and bracing the conveying belts 10, 12 comprise a plurality of profiles 52 with a substantially C-shaped cross-section which are arranged at predetermined distances, transversely with respect to said conveying belts 10, 12, and are fixed, at their ends, to the inner face of said wall 42.

8. Machine according to Claim 7, characterized in that the parallel sides of the supporting and bracing profiles 52 are arranged parallel to the direction of the feeding movement of the conveyor belts 10, 12.

9. Machine according to Claim 1, characterized in that said supporting and bracing members 52 and said conveyor belts 10, 12 have arranged between them spacing means 56, 54 which on one side are integral with said supporting and bracing means 52, while on their other side they engage, in a supporting and sliding manner, with said conveyor belts 10, 12.

10. Machine according to Claim 4, characterized in that said conveyor belts 10, 12 consist of a plurality of links 10a, 12a which are hinged together, there being between adjacent links a certain play which allows the pressed product to fall freely towards the underlying collection trays.

11. Machine according to Claim 10, characterized in that the links 10a, 12a forming said conveyor belts 10, 12 are provided with a plurality of holes designed to allow the pressed product to pass through towards the underlying collection trays.

12. Machine according to Claim 6, characterized in that said side wall 42 associated with one of the conveyor belts 10, 12 extends as far as the region of the opposite conveyor belt 10, 12, its end making contact with the possibility of sliding with respect to a profile having a substantially C-shaped cross-section which in turn is integral with said means 52 for supporting and bracing the conveyor belt 10, 12.

13. Machine according to Claim 6, characterized in that said side wall 42 is associated with the lower conveyor belt 12 and its bottom end is rigidly connected to a lower cross-beam 80 connected, at its end, .to a lower portion 34b of the uprights 34 of the portal structure 32, the upper portion 34a of which is connected to said lower portion 34b via said pressing means 26, so as to cause raising of the lower belt 12.

14. Machine according to Claim 4, characterized in that said upper and lower conveyor belts 10, 12 are inclined upwards in the direction of feeding of the product to be pressed.

15. Machine according to Claim 4, characterized in that, below said upper and lower conveyor belts 10, 12, there is arranged a plurality of trays 68, 70, 72, each of which is designed to receive the pressing product obtained by the action of one of said pressing means 26.

16. Machine according to Claim 15, characterized in that the collection trays 68, 70 and 72 are separate from one another and are each provided with means for discharging the pressing product 74, 76 and 78.

17. Machine according to Claim 4, comprising, in the region where the product to be pressed is introduced between said two upper and lower conveyor belts 10, 12, a loading hopper 14, characterized in that, in the bottom part of the loading hopper 14, there is provided a substantially transverse drum 18 which is connected to drive means for effecting rotation thereof and is provided on its contour with radial vanes 20 designed to push and introduce the product during pressing between said two conveyor belts 10, 12 when the drum 18 is rotated.

18. Machine according to Claim 17, characterized in that said radial vanes 20 are made of elastically deformable material.

19. Machine according to Claim 18, characterized in that, along the path of said radial vanes 20, there are provided means designed to prevent the product to be pressed from rising up above the drum 18.

20. Machine according to Claim 19, characterized in that said means designed to prevent the material to be pressed from rising up above the drum 18, consist of at least one roller 24 arranged substantially parallel to the drum 18 and mounted in a freely rotatable manner on the side walls of the loading hopper 14, said radial vanes 20 of the drum 18, when they come into contact with said roller 24, undergoing elastic deformation which allows rotation of the drum 18.

21. Machine according to Claim 18, characterized in that the width of said radial vanes 20 is slightly greater than the distance between the contour of the drum 18 and the bottom wall of the loading hopper 14 which is provided with a plurality of substantially longitudinal slits 22 designed to allow a first pressing of the product to be pressed by said radial vanes 20.

22. Machine according to Claim 20, characterized in that, during rotation of the drum 18, the end edges of the radial vanes 20 in contact with the bottom wall of the loading hopper 14 are bent slightly so as to facilitate both pushing of the product to be pressed towards the conveyor belts 10, 12 and effect said first pressing through said slits 22 in the bottom wall of the loading hopper 14.

23. Machine according to Claims 4 and 6, characterized in that said belt is hingeably articulated in the region of the zones of the belt 10, 12 where the pressing means 26 are provided.

24. Machine according to Claim 23, characterized in that each of said hinges consists of at least one transverse roller 82 which engages with either the upper or lower section of the belt and is supported in a freely rotatable manner on the ends by support means connected to the end of the rod 36 of the piston 28.

25. Machine according to Claim 4, characterized in that each of said upper and lower conveyor belts 10, 12 consists of several sections or conveyor belts separated from one another and connected so as to be fed in a synchronized manner, each of said sections corresponding to one of said pressing means 26.

26. Machine according to Claim 3, characterized in that the conveying means comprise a conveyor belt 12 which feeds the products to be pressed, pressing of which is performed by pressing means 11 with which the pressure means 26 are provided and which each consist of a substantially flat body or element which extends longitudinally above the conveyor belt 12, the lateral edges of said substantially flat body or element being fixed to side walls 42 displaceable vertically by thrusting means 28 mounted on the fixed frame of the machine.

27. Machine according to Claim 26, characterized in that said pressing means 11 are separate from one another.

28. Machine according to Claim 26, characterized in that said pressing means 11 each consist essentially of a plurality of slats fixed together so as to form a flat one-piece body.

29. Machine according to Claim 26, characterized in that said pressing means 11 each consist of a bored plate.

30. Machine according to Claim 26, characterized in that said pressing means 11 each consist of a solid-wall plate.

31. Machine according to Claim 26, characterized in that said pressing means 11 each consist of a meshwork.

32. Machine according to Claim 31, characterized in that said meshwork is made of metal.

33. Machine according to Claim 26, characterized in that bracing profiles 13 are applied at least in the region of the ends of each pressing means 11, said profiles also being fixed at their ends to said side walls 42.

34. Process according to Claim 1, characterized in that said plant product consists of grapes.

35. Machine according to Claim 26, characterized in that said plant product consists of grapes.