PNEUMATIC PRESS

Abstract

 A press (MC) is described for pressing a vegetable product, and a control method for the press.
The press comprises a drum (10) rotatable about a horizontal axis (X) and provided with a draining sieve (12) to separate the solid and liquid part of the vegetable product,
wherein the volume of the drum (10) consists of two or more isolated load volumes, and in each load volume being installed an inflatable membrane (50a, 50b) for pressing the vegetable loaded therein against a respective draining sieve.

Description

[0001] The invention concerns a pneumatic press for pressing a vegetable product, the control method for the press and software implementing the control. The following description will be referenced to winemaking, a sector in which the invention has proved itself particularly effective.

[0002] Pneumatic presses are known for pressing a vegetable product, e.g. as in EP2342071. Crushed material is loaded and then pressed in a horizontal-axis rotating drum with an inflatable membrane which carries out the separation of the liquid part from the peel through perforated collection channels placed on the inner surface of the drum.

[0003] A first type of press includes a single inflatable membrane to invade the entire cylindrical volume of the drum. The disadvantages are several, including a limited draining area compared to the drum volume (since only half of the drum can act as a draining surface). In case of rupture of the membrane, the press is out of order with enormous problems during the harvest, and the mass to be filtered translates into high pressures to be applied to obtain a good pressing speed.

[0004] A second type of press is equipped inside the drum with two inflatable membranes applied to the two internal half-walls of the same acting simultaneously, while pressing the mass, towards draining channels which diametrically cross (in cross-section) the drum. The disadvantages of this solution are the design complexity, especially for large capacity presses; limited draining surface with respect to the volume of the press; the impossibility of applying cooling surfaces to the drum (since 'this is occupied entirely by the membranes); and high difficulty of automatically cleaning the internal channels; low mechanical resistance to impacts of the central drains which results in potential and dangerous breakages. Moreover, in case of breakage of a single membrane the press is completely out of order, and it is very difficult to empty the drum because the radial channels strongly interfere.

[0005] A third and last type of press (see e.g. EP0721836) is similar to the first, with the difference that the drainage channels are arranged on all or most of the inner surface of the drum and the tubular-type inflatable membrane presses radially from the drum axis towards the outside. A major drawback of this configuration is the design complexity. To support the tubular membrane inside the drum a massive axial structure is needed, which creates big problems both during the emptying phase both in the rotation phase during the pressing cycles. And the structure creates remarkable organoleptic damage to the product being processed. The central membrane must have a surface equal to the inner one of the drum, therefore it is double the size of the press of the first type, with creation of noticeable wrinkles by the membrane's sucking itself, which creates major problems also in the press washing phase. To overcome the problem of membrane size and wrinkles, the few manufacturers of this type of press also offer elastic membranes, which, unlike traditional polyurethane plastic membranes, are very fragile, and therefore subject easily to disastrous breaks during work. Not only is the cost higher, but the membrane involves enormous difficulty in assembly and disassembly in the event of maintenance or breakage. Consequently, in case of breakage of the membrane the press is out of order for a long time.

[0006] The present invention has as its main object to improve this state of the art, and
as particular object the realization of a press that alleviates the aforementioned problems.

[0007] A first aspect of the invention is a vegetable product press, e.g. crushed grapes, comprising:

a drum rotatable about a horizontal axis and provided with a draining sieve to separate the solid and liquid part of the vegetable product,

wherein the volume of the drum consists of two or more isolated load volumes,

in each load volume being installed an inflatable membrane for pressing the vegetable loaded therein against a respective draining sieve.

[0008] The invention includes the variant of a hollow rotating drum whose internal cavity is partitioned to obtain smaller isolated load volumes and isolated from each other. The press then comprises:

a hollow drum rotatable about a horizontal axis and provided on its lateral inner surface with a draining sieve to separate the vegetable product in part solid and liquid part,

wherein the inner volume of the drum is partitioned by two or more isolated load volumes,

in each load volume an inflatable membrane being installed to press vegetable product against a respective draining sieve.

[0009] Preferably the press comprises a single drum internally partitioned into sub-volumes.

[0010] The invention is applicable both when the draining sieve is a perforated drum wall (so that the vegetable product pressed by the membrane pushes the liquid part directly to the outside of the drum through the perforated wall), and when the draining sieve comprises or consists of one or more drainage channels (the drum is closed) from which the liquid part is conveyed towards the outside of the drum through one or more liquid collectors.

[0011] The invention also includes the variant of a revolving drum formed by smaller load sub-volumes (or shells), isolated from each other and connected integrally. The smaller load sub-volumes are separated parts and separable from each other, but juxtaposed and fixed together to constitute a composite drum.

[0012] It follows that two load sub-volumes of the composite drum are separated from each other by at least two respective adjacent walls, i.e. the walls delimiting the volume of each sub-volume (i.e., between two sub-volumes there is not a single shared and dividing wall). Said walls, in the compound drum, may be in contact, partially in contact or kept separate from the means that hold the load sub-volumes rigidly together to form the drum. Note that the construction with sub-volumes formed by closed shells makes the drum overall.

[0013] Preferably, the composite drum has a cross section (taken with respect to a plane orthogonal to the longitudinal rotation axis of the drum), given by the composition of the transversal cross-sections of the load sub-volumes, which is e.g. substantially inscribed or contained in one circumference or in one ellipse. In particular the load sub-volumes are arranged with polar symmetry about an axis, which will be the rotation axis of the overall drum.

[0014] In the case of the composite and unpartitioned drum, the load sub-volumes may have or not walls in contact at the rotation axis of the overall drum. This by virtue of the fact that the walls of the load sub-volumes, at the rotation axis of the overall drum, may be spaced apart, e.g. to make room for mutual fixing means, or may touch at some points thanks to a curvature of theirs. In particular, the wall of each sub-volume that is closest to the rotation axis of the overall drum may be, with respect to a radius starting from such axis towards the outside of the drum, concave or convex or flat. In other words, said closest wall comprises a surface facing the rotation axis of the drum which has a concavity or a convexity. Since the inflatable membrane at rest is preferably extended over said closest wall and when inflated moves away from the rotation axis of the overall drum, the concavity or convexity is useful for distributing the reaction force discharged by the membrane onto said wall. The symmetrical arrangement of the sub-volumes around the rotation axis of the overall drum also facilitates the cancellation of the thrusts (which are opposite) on the respective walls closest to said axis.

[0015] In the following, by sub-volumes it is meant both load volumes derived from the partitioning of the inner volume of a single drum, and shells that form load volumes and, when assembled juxtaposed, make up the drum of the press.

[0016] The two or more sub-volumes that subdivide or constitute the inner volume of the drum are independent and isolated from each other, and preferably equal to each other.

[0017] Each sub-volume has its own pressing membrane that is inflatable to press the vegetable product against the draining sieve present in that sub-volume. In particular, the pressing membrane is inflatable to press the vegetable product towards the outside of the drum, i.e. against the inner side surface of the drum. Other positions for the draining sieve are also possible.

[0018] Each sub-volume is equipped with a draining sieve to separate the vegetable product into a solid part and a liquid part.

[0019] Preferably a or the draining sieve of a or each sub-volume is comprised in the inner side surface of the drum, but other positions are also possible, e.g. the or a draining sieve of a or each sub-volume is comprised in the inner side surface of the sub-volume itself.

[0020] Preferably the draining sieve of each sub-volume is independent of the others, and is e.g. connected to a distinct duct adapted to drain the liquid collected from the respective sieve.

[0021] Preferably the inner volume of the drum is partitioned into two or more circular sectors.

[0022] Preferably the drum internally comprises at least one dividing partition, to partition its internal volume into two or more isolated load volumes. In particular, the dividing partitions extend from separate and distinct points of the inner lateral surface of the drum, more particularly the dividing partitions extend from diametrically opposite points of the inner lateral surface of the drum.

[0023] With the structure defined above, numerous advantages and various methods of use are obtained, including:

1. The press never stops: in case of breakage of a membrane the press continues to work with the remaining sub-volumes. This feature makes it very advantageous compared to the three types of presses described above. which stop when a membrane breaks. Statistically it is very unlikely that the membranes of the sub-volumes break at the same time. During the harvest, when the presses work day and night, it is essential to press the freshly picked-up grapes as quickly as possible in order to prevent the product from deteriorating.

2. The draining surface is overall equal to all or almost all the inner surface of the drum. This results in a high draining speed.

3. The press can work at reduced load with a subset of sub-volumes, as if it were one or two lower-capacity presses. This benefits the operational flexibility with the associated capacity of being able to work different vegetables separately (in this case the draining points of each sub-volume are made to drain in separate tanks).

4. Multiple processing speed: by equipping each N-th sub-volume with an output for the pressed solid part, at every turn of the drum one can unload N times; or one can load or unload a sub-volume of vegetable product while in another sub-volume pressing occurs.

5. Different pressing programs for each N-th sub-volume, which is loaded with its own vegetable product.

6. Ease to wash the inside of both the press and the drainage channels, and this above all compared to traditional double-membrane presses with a central tubular membrane.

7. Preferably, the press comprises independent thermoregulation pockets for each sub-volume and/or on the entire inner surface of the drum, so as to be able to thermally process each sub-volume independently.

[0024] In general, the drum comprises one or more partition, e.g. diametral or radial, walls for partitioning its inner volume into N independent and separate sub-volumes. Preferably N = 2, and the drum comprises a single diametral partition wall to subdivide into two independent and separate sub-volumes its inner volume. Or, generally, the drum is composed of R independent and separate sub-volumes, preferably each in the form of a shell that defines a closed volume.

[0025] Preferably R = 2, and the drum is formed by the assembly of two independent and separated sub-volumes.

[0026] Preferably the partition walls extend from the axis of the drum towards its periphery, but also walls that do not intersect the rotation axis of the drum and/or even not flat walls may also be realized.

[0027] In each of the N or R sub-volumes an inflatable membrane is mounted to push the vegetable product towards sieves or draining channels, which are preferably placed on the inner surface of the drum. In particular, the membrane is inflatable so as to press the vegetable product towards the fraction of inner surface of the drum which belongs to that sub-volume. In particular, the membrane is inflatable starting from the center of the drum towards the outside. Preferably the membrane is inflatable starting from a position, in which the membrane is placed on or near the dividing wall of the sub-volume (e.g. the membrane is nearly spread), to a position wherein the membrane is spaced from the partition wall of the sub-volume and closer to the inner surface of the cylinder (e.g. the membrane takes the form of a cap).

[0028] In each of the N or R sub-volumes the inflatable membrane is preferably mounted so that the edges of the membrane are on the inner surface of the drum. In particular, in each of the N or R sub-volumes the inflatable membrane is preferably mounted so that the edges of the membrane coincide with the connecting sections between the inner surface of the drum and a dividing wall.

[0029] In general the N or R sub-volumes do not necessarily have to be equal or of the same capacity.

[0030] Preferably each N-th or R-th sub-volume comprises a loading/unloading port, to better evacuate the pressed solid part.

[0031] Preferably each N-th or R-th sub-volume comprises an independent inlet for the axial (or not axial) load of the vegetable product.

[0032] Preferably each N-th or R-th sub-volume comprises an independent inlet of fluid for inflation and deflation of the respective membrane.

[0033] The membrane of each N-th or R-th sub-volume can be inflated and deflated, e.g. by compressors and aspirators, independently of the membranes of the other (N-1) or (R-1) sub-volumes. Advantageously the same compressor and aspirator can be used for all or many membranes, if the press comprises flow deflection valves to selectively divert fluid flow coming from a compressor or aspirator towards two or more membranes to inflate or deflate them.

[0034] A second aspect of the invention is a control method for a press as defined herein, in one or each of the described variants. The method has these favorite steps:

filling at the same time all the sub-volumes with product to be pressed, and then pressing at the same time the product loaded in the sub-volumes of the press; and/or

filling with product to be pressed only a subset of the sub-volumes and then press the product loaded only in those sub-volumes of the press; and/or

rotating the drum overall by 360 degrees and sequentially unload pressed solid part present in all the sub-volumes; and/or

loading or unloading a sub-volume with vegetable product while in another sub-volume the pressing is executed by inflating therein the respective membrane; and/or

adjusting pressing pressures and/or pressing times and/or the temperature of each sub-volume in independent way.

[0035] A third aspect of the invention is another method of controlling a press as defined herein, in one or each of the described variants. The method has the steps of:

filling all the sub-volumes of the press with product to be pressed at the same time,

then simultaneously pressing the product loaded into the sub-volumes.

[0036] Preferably the steps of the method are carried out through the instructions of a program loaded and executed in a microprocessor.

[0037] In particular, the operation of the press is preferably managed by an electronic programmable unit, such as a PLC.

[0038] In particular, the programmable electronic unit determines the pressing cycles and controls the various operating phases by controlling the components of the press, such as e.g.
the motor that turns the drum,
the axial or non-axial loading of one or more independent sub-volumes;
a compressor and an aspirator to inflate or deflate independently the membranes of the press,
flow deflection valves to divert fluid, put under pressure by the compressor and/or the aspirator, to and from one of the membranes of the press,
drain valves to let juice out of every N-th sub-volume;
one or more hatches for loading and unloading the product to/from each sub-volume.

[0039] Another aspect of the invention relates to a method for building the drum of a press for a vegetable product, e.g. crushed grapes, wherein the drum is rotatable about a horizontal axis and equipped with a draining sieve to separate the vegetable product into solid and liquid part, wherein the volume of the drum is constituted of two or more insulated loading volumes, in each loading volume there being an inflatable membrane to press vegetable product against a respective draining sieve,
with the step of
building the drum as a composition of smaller load sub-volumes or shells, mutually isolated and connected together.

[0040] A preferred embodiment of the press will now be described with reference to the annexed drawing, wherein

fig. 1 shows a side view of the press;

figures 2-4 show front views in transparency of the press in various operating configurations;

fig. 5 shows a perspective view of a variant of the press;

fig. 6 shows a front view of the variant of fig. 5;

fig. 7 shows a view from above of the variant of fig. 5.

fig. 8 shows a second variant of the press in perspective view;

fig. 9 shows a front view of the variant of fig. 8;

fig. 10 shows a view from above of the variant of fig. 8.

[0041] In the drawings equal numerical references indicate equal parts, and relative terms as horizontal refer to the press as in use. In order not to crowd the figures, some repeated elements are not always indicated.

[0042] A press MC comprises a closed hollow, e.g. cylindrical, drum 10 raised from the ground by a frame. The drum 10 can rotate about a horizontal axis X in a known manner driven by a motor 20.

[0043] As an alternative to the cylindrical closed drum 10, it is possible to have a perforated, therefore open, cylinder where the juice drains directly outside passing through the holes made in the cylinder's wall itself. It is understood that only for descriptive brevity we refer here to a closed cylinder, whereas all the variants and advantages shown here apply to the open cylinder.

[0044] Evenly distributed on the inner surface of the drum 10, there are longitudinal draining channels 12, which extend parallel to the axis X for most of the length of the drum 10. The draining channels 12 communicate with the collecting ducts 18 which carry the juice extracted from the pressing out of the drum 10, e.g. towards a collection tank 16.

[0045] The drum 10 is internally divided into two equal semi-cylindrical sub-volumes 42a, 42b by a diametrical flat wall 40 (fig. 2). This flat wall may be e.g. also composed of a double reinforced wall, of a concave-convex wall, of a double concave-convex wall or of other concave or convex shape or of another form suitable to allow a correct subdivision of the inner volumes of the drum and their resistance to pressure.

[0046] The semi-cylindrical sub-volumes 42a, 42b can be loaded with product to be pressed through two independent ducts 14, and each contain a membrane 50a, 50b inflatable independently by means of a compressor 22 and deflatable independently by means of an aspirator 24. The membranes 50a, 50b in the figures are drawn in dashed lines to better highlight them.

[0047] Each membrane 50a, 50b is mounted so that at rest (when deflated) it is nearly spread out against the respective face of the diametrical wall 40, while in action (when it is inflated) it expands from the diametrical wall 40 towards the portion of inner wall of the drum 10 opposite to the surface of the diametrical wall 40 from which it departed. Fig. 3 shows the initial pressing phase, when each membrane 50a, 50b has moved away from the axis X and is moving towards the periphery of the drum 10 (see arrows F) pressing the vegetable product P against the channels 12. The juice S thus generated is conveyed into the manifolds 18 and collected in the tank 16 under the press MC.

[0048] The inflation and deflation of each membrane, the working times and the pressures in each sub-volumes can be the same or different. In the first case, the system works as a "push-pull", wherein the pressures balance each other without stressing the partition wall 40. In the second case, the partition wall is sized to withstand independent pressurization and depressurization of the sub-volumes.

[0049] In known manner the rotation of the drum 10 about the axis X serves to break up and expel the solid part T of the pressed vegetable product which remained packed against the draining channels 12 (see Fig. 4) or - in the case of an open cylinder - against its draining perforated wall.

[0050] The operations of the press MC are preferably managed by a programmable electronic unit or a PLC. In particular, the programmable electronic unit or the PLC manages
the motor 20,
the compressor 22 and the aspirator 24, and
all the valves of the press MC.

[0051] The longitudinal draining channels 12 may be of a shape different from the one illustrated.

[0052] In general, the drum 10 may be

• internally divided into any number of sub-volumes, not necessarily just two; and/or
• divided internally by any number of dividing partitions, not necessarily flat and not necessarily arranged radially with respect to the axis of the drum.

[0053] Figs. 5-8 show a variant MC2 of the press which has a drum, rotatable about a horizontal axis X, consisting of two isolated loading volumes. The press MC2 comprises a drum 100 that, like the drum 10, can rotate about a horizontal axis X in a known way driven by a motor.

[0054] The difference with respect to the previous variant is that the drum 100 is formed by the mechanical union of two equal smaller cylinders or drums 110, insulated from each other and rigidly connected together by brackets 120.

[0055] Substantially, each cylinder or drum 110 is constituted of a shell with rigid walls which enclose a closed volume, and these walls are rigidly fixed with respect to the walls of the adjacent cylinders or drums 110 to form the drum 100.

[0056] Each cylinder or drum 110 comprises on its inner surface longitudinal drainage channels, which extend parallel to the axis X for a good part of the length of the drum 110. The drainage channels communicate with collecting ducts which carry the juice extracted from the pressing out of each drum 110. Or each cylinder or drum 110 has the side surface perforated for draining the pressed juice.

[0057] The drums 110 each contain an independently inflatable membrane to press the product loaded into them. What has been said before for the management and operation of the sub-volumes 42a, 42b is applicable to the drums 110, and is not repeated.

[0058] It is then understood that the press MC2 shares all the advantages of the press MC, since the separate and/or programmed use of the load volumes made with the drums 110 provides the same effects and results.

[0059] The press MC2 can be easier to build when in some cases the internal partition of the drum 10 is difficult, and can exploit the modularity of the drums 110 for a serial assembly.

[0060] The drum 100 may be formed by the mechanical union of any number of (preferably equal) smaller cylinders or drums rigidly connected together. It is sufficient that the assembly formed by the mechanical union of the smaller cylinders or drums forms a composite drum.

[0061] For the mutual rigid connection of the aforementioned smaller cylinders or drums other means may be used, such as welds, rivets, or connecting frames or beams.

[0062] In the press MC2 the cylinders or drums 110 contain an inflatable membrane which at rest is laid out on a wall 150, the wall closest to the axis X. In the example of Figures 6-8 the connecting means are anchored to the walls 150. When the membrane gets inflated, it moves radially away from the axis X towards the opposite wall of the cylinders or drums 110.

[0063] It can be noted that the wall 150 is convex with respect to an imaginary radius which from the axis X propagates towards the outside of the drum 100. In other words, the axis X extends in a space external to the cylinders or drums 110, because thanks to the convexities of each cylinder or drum 110 an empty space is created at the center of the drum 100, around the axis X (and e.g. the empty space is exploitable to install the connection means therein).

[0064] The convex walls 150 are useful to withstand the reaction thrust of the inflatable membrane.

[0065] Figures 8-10 show another variant MC3 of the press. As for the press MC2, the press MC3 comprises a composite drum 200 similar to the drum 100. Basically, the drum 200 is composed of smaller clinders or drums 210, each constituted by a shell with rigid walls enclosing a closed volume, and these walls are rigidly fixed with respect to the walls of the cylinders or adjacent drums 210 to form the drum 200.

[0066] The construction details described for the press MC2 are valid for the press MC3, and are not repeated.

[0067] The only difference between the presses MC2 and MC3 is the shape of the smaller cylinders or drums that make up the overall drum.

[0068] While in the cylinders or drums 110 the wall 150 closest to the axis X is convex (with respect to an imaginary radius which propagates from the axis X towards the outside of the overall drum), in the press MC3 the homologous wall 250 is concave.

[0069] The walls 250 of the cylinders or drums 210 may be in contact or separated.

[0070] In the first case the axis X extends in a space external to the cylinders or drums 210, because between the concavities of each cylinder or drum 210 at the center of the drum 100, around the axis X, there is an empty space (and e.g. is usable to install the connection means).

[0071] In the second case, the axis X extends by touching or remaining within the walls 250.

[0072] The concave walls 250 are useful to withstand the reaction thrust of the inflatable membrane, and are reasonably simpler to build.

Claims

1. Press (MC) for a vegetable product, e.g. pressed grapes, comprising:

a drum (10) rotatable about a horizontal axis (X) and provided with a draining sieve (12) to separate the solid and liquid part of the vegetable product,

wherein the volume of the drum (10) consists of two or more isolated load volumes,

in each load volume being installed an inflatable membrane (50a, 50b) for pressing the vegetable loaded therein against a respective draining sieve.

2. Press (MC) according to claim 1, wherein the rotating drum is formed by the juxtaposition of smaller load sub-volumes or shells, mutually isolated and integrally connected to each other.

3. Press (MC) according to claim 1 or 2, wherein the drum has a cross-section, taken with respect to a plane orthogonal to the longitudinal rotation axis of the drum, which is given by the additive composition of the cross-sections of the load sub-volumes or shells.

4. Press (MC) according to claim 1 or 2 or 3, wherein the cross-section given by the additive composition is substantially inscribed or contained in a circumference or an ellipse.

5. Press (MC) for a vegetable product according to claim 1, comprising:

a hollow drum (10) rotatable about a horizontal axis (X) and provided on its inner side surface with a drainage sieve (12) for separating the solid and liquid part of the vegetable product,

wherein the internal volume of the drum (10) is partitioned into two or more isolated load volumes,

in each load volume being installed an inflatable membrane (50a, 50b) for pressing the vegetable loaded therein against a respective draining sieve.

6. Press (MC) according to claim 5, comprising one or more dividing partitions (40) for partitioning the internal volume of the drum (10) into the two or more isolated load volumes, wherein the dividing partitions extend from separate and distinct points of the internal side surface of the drum.

7. Press (MC) according to claim 5 or 6, wherein the inner volume of the drum (10) is partitioned into two equal semi-cylindrical sub-volumes.

8. Press (MC) according to any one of the previous claims, wherein one or each inflatable membrane is mounted so that at the beginning of inflation it moves from the center of the drum towards the outside or from the rotation axis of the drum towards the outside.

9. Press (MC) according to any one of the previous claims, wherein one or each membrane is inflatable starting from a position, in which the membrane is placed on or near the dividing partition of the sub-volume, towards a position in which the membrane is spaced from the divider partition of the sub-volume and closer to the inner surface of the cylinder, or wherein one or each membrane is inflatable starting from a position, in which the membrane is placed on a wall of the sub-volume, said wall being the closest to the rotation axis of the drum, towards a position in which the membrane is spaced from the rotation axis of the drum and closer to the opposite surface of the sub-volume.

10. Press (MC) according to claim 9, wherein in each of the sub-volumes the inflatable membrane is mounted such that the edges of the membrane lie on the inner surface of the drum or on said closest wall.

Drawing