EP0211706B1 - Process and apparatus for separating liquids and solids, in particular fruit juices - Google Patents

Description

Presses have been known for a very long time, which are particularly suitable for extracting fruit juices and which include a capacity with perforated walls into which the materials to be pressed are introduced and compressed by means of an endless screw. This general principle knows many variations, in particular in the shape of the hub of the worm and in the shape of the compression capacity itself. Whatever these variants, all presses of this type have the major drawback of causing crushing of the material to be pressed between the periphery of the central screw and the perforated walls of the container, because there is necessarily friction on the turns of the screw and on the perforated walls which act as a grater.

These drawbacks are very serious since they lead to the fragmentation of solid materials and the crushing of seeds or herbaceous fractions, which causes an evolution of oil giving a bitter taste and giving the extracted juice an astringency incompatible with good quality.

Thus we know the document FR-A-74/09591 which describes a press having a compression capacity with perforated walls of cylindrical shape and a central helical screw itself cylindrical but whose hub has several parts of different conicities.

Document FR-A-82/03408 is also known, which describes a press having a first cylindrical part and a second frustoconical part, an axial helical screw having turns which are themselves cylindrical on a hub which is also cylindrical.

Document FR-A-83/05068 describes a press having a compression capacity having a first cylindrical part, a second frustoconical part connected to the first and a third also cylindrical part connected to the frustoconical part, the helical screw always having a cylindrical outline.

It can be seen that in all cases the pressure exerted on the material is generated by the rotary helical screw, the source of the drawbacks mentioned above, the gravity of which is such that it has caused the prohibition of presses of this type for the production of grape juice intended for the production of Cognac.

It was then thought to eliminate the crushing by rendering harmless the helical screw rotating in the axis of the compression capacity. For this purpose, the helical screw is mounted axially movable while being rotatably mounted in the direction of a thrust on the material. When this screw meets a predetermined resistance, it is moved back to a starting position then, the rotation being stopped, the screw is pushed axially, without turning, on the material already pressed while we admit fresh material to press and the screw is removed by driving it in rotation in the opposite direction to the push so that it "unscrews" in the fresh material, then the cycle begins again.

This device provides an improvement over the previous presses but still has a significant drawback in that the pressure is exerted in the same direction as the introduction of the material, that is to say in a direction called "upstream-downstream" "and that, in addition, this pressure is predominant at the center of the capacity, the compulsory back pressure being obtained by means of a door placed across the end of the capacity opposite the entry of the material to be pressed.

For the record, we can cite the press which has a compression capacity in which there are two helical screws with reverse pitch on each of which is fixed a plate of the same section as the capacity and which plays the role of nut when puts the capacity in rotation, the screws being kept fixed, because the plates approach to press the material placed between them or move away to release it according to the direction in which the compression capacity is driven.

A press of this type, known for many years, also has a very poor yield since the duration of obtaining a "press" is three and a half hours and this time causes the oxidation of the tannins and all oxidizable substances including aromas, all resulting in a dark juice without taste or odor when the material to be compressed is a grape.

It can therefore be seen that pressing a heterogeneous mixture is a difficult operation if a good yield is to be achieved, that is to say the extraction of at least eighty percent of liquid fraction for twenty percent of solid fraction, all while obtaining good quality at an economical price.

The present invention provides a solution constituting a considerable improvement since it provides for the presence of a conical shield which allows overpressure at the output of a pressing capacity, this capacity being made movable relative to a fixed piston. In this way, an assembly is produced which avoids all attacks against the mixture to be pressed and which has an excellent yield.

The present invention, moreover, provides the means to improve the distribution of the working pressure in the capacity by using various alternative embodiments of the means which cause this pressure.

To this end, the subject of the invention is a method for separating by pressing liquid and solid fractions intimately associated into a heterogeneous mixture, as are, for example, the juices, pulps, pits, seeds, peduncles and plant elements of fruit such as grapes harvested, of the type according to which one fills in a direction known as "upstream-downstream", by a so-called entry end, a capacity with side walls crossed by fine passages, with heterogeneous mixture, then that one interrupts the mixing, and then causes pressing by producing a linear relative movement between the capacity and a non-rotating part forming a piston situated in front of the inlet end so that this part penetrates from upstream to downstream in the capacity, characterized in that a antagonistic retaining force, that is to say directed in the "downstream-upstream" direction, coaxial with the capacity, at the end of the said outlet known opposite to the previous one and acting on the heterogeneous mixture fractions introduced, thus progressively agglomerated into a cake of solid fractions, while providing an annular outlet space, also coaxial, then only after pressing the heterogeneous mixture simultaneously causing the exit of at least part of the liquid fractions through the walls of the capacity and the exit of a part of the cake of solid fractions by the exit space, one stops the linear relative movement, then that one causes a new entry of mixing and its pressing in the capacity according to a pressure coordinated with the value of the output holding force and so on in successive cycles.

• pour causer le pressage on maintient immobile la capacité et l'on déplace la pièce formant piston dans le sens amont-aval selon un mouvement de coulissement axial par rapport à ladite capacité;
• on coordonne la pression dans la capacité et la force de retenue antagoniste pour établir dans ladite capacité une pression faiblement croissante depuis l'extrémité d'entrée jusqu'à une zone située au voisinage de l'extrémité de sortie, zone à partir de laquelle on provoque une nette augmentation de la force de retenue.

According to other preferred characteristics of this process:

• to cause pressing, the capacity is kept stationary and the piston piece is moved in the upstream-downstream direction in an axial sliding movement with respect to said capacity;
• the pressure in the capacity and the opposing retaining force are coordinated to establish in said capacity a slightly increasing pressure from the inlet end to an area located near the outlet end, area from which causes a marked increase in the holding force.

The subject of the invention is also a device for implementing the above method, of the type comprising a capacity whose side walls are crossed by fine passages and which has two opposite open ends, one of which is said to be "inlet" is placed opposite a piston-forming part and provided with an opening for the entry of mixture into the tank, characterized in that the tank has an increasing section from upstream to downstream and in that the device has a shield associated with the other end called "outlet", the shield capacity assembly being mounted movable relative to the piston-forming part in order to press the material against the shield where cakes of solid fractions are finished which must then be evacuated around the shield.

• le bouclier est monté mobile élastiquement dans le sens longitudinal de la capacité afin de laisser subsister un passage annulaire coaxial plus ou moins grand pour la sortie des fractions solides, des moyens étant prévus pour provoquer un mouvement relatif linéaire entre la capacité et la pièce formant piston;
• la pièce formant piston est constituée par une paroi frontale d'une douille creuse qui est située à l'extrémité d'une cuve munie d'une trémie pour l'introduction de mélange hétérogène et qui est associée à une vis rotative axiale située en regard d'une ouverture traversant en son centre la paroi frontale de la douille, cette vis étant conformée pour présenter à son extrémité, au moins une partie substantiellement perpendiculaire à l'axe de la vis;
• la pièce formant piston est montée mobile, tandis que la capacité est immobile;
• la pièce formant piston est constituée par au moins un filet de vis indépendant et qui est relié cinématiquement à deux mécanismes distincts susceptibles de l'entraîner seul, respectivement en rotation et en translation axiale et dont l'extrémité est conformée pour présenter au moins une partie substantiellement perpendiculaire à son axe;
• l'axe de la vis est creux et est traversé librement par un arbre portant le filet de vis qui se trouve ainsi dans le prolongement de la vis, cet arbre étant relié aux mécanismes susceptibles de l'entraîner respectivement en rotation et en translation axiale, indépendamment de l'axe de la vis;
• la paroi frontale présente une ouverture centrale munie d'un clapet anti-retour;
• la capacité et/ou le bouclier ont des profils déformables;
• le profil de la capacité présente des courbures ou lignes brisées déformables avec ou moins un point d'inflexion;
• le profil du bouclier présente des courbures ou lignes brisées déformables avec au moins un point d'inflexion;
• les profils déformables sont susceptibles de présenter des parties soit convexes, soit concaves;
• il comporte un mécanisme de freinage disposé à la sortie de la capacité;
• le mécanisme de freinage est constitué par une jupe placée dans le prolongement de la capacité;
• le mécanisme de freinage comprend au moins une partie annulaire mobile en rotation et associée à des moyens susceptibles de l'entraîner de préférence à vitesse réglable;
• la partie annulaire comprend une couronne solidaire d'au moins une pièce intérieure de forme hélicoïdale à au moins une spire, le sens de rotation et le pas de la pièce hélicoïdale étant adaptés à l'évacuation des fractions solides et non à leur compression;
• la partie annulaire comprend une couronne solidaire d'ailettes hélicoïdales intérieures;
• la capacité est associée, dans l'axe de cette dernière, à un évacuateur de fractions solides constitué par une vis dont le diamètre est avantageusement croissant dans le sens amont-aval, des moyens étant prévus pour provoquer un mouvement de rotation relatif entre la capacité et la vis;
• le bord extérieur de la vis est aigu;
• la capacité présente des nervures internes longitudinales;
• le bouclier est de type filtrant, c'est-à-dire percé de trous pour le passage de fractions liquides;
• la section de la capacité et celle du bouclier est soit circulaire, soit polygonale.

According to other preferred characteristics of this device:

• the shield is mounted movable elastically in the longitudinal direction of the capacity in order to leave a coaxial annular passage of varying size for the exit of the solid fractions, means being provided for causing a linear relative movement between the capacity and the piston-forming part ;
• the piston-forming part is constituted by a front wall of a hollow sleeve which is situated at the end of a tank provided with a hopper for the introduction of heterogeneous mixture and which is associated with an axial rotary screw situated opposite an opening passing through the front wall of the bushing at its center, this screw being shaped to present at its end, at least one part substantially perpendicular to the axis of the screw;
• the piston-forming part is mounted mobile, while the capacity is stationary;
• the piston-forming part is constituted by at least one independent screw thread and which is kinematically connected to two separate mechanisms capable of driving it alone, respectively in rotation and in axial translation and the end of which is shaped to present at least one part substantially perpendicular to its axis;
• the axis of the screw is hollow and is freely traversed by a shaft carrying the screw thread which is thus in the extension of the screw, this shaft being connected to the mechanisms capable of driving it respectively in rotation and in axial translation, regardless of the axis of the screw;
• the front wall has a central opening provided with a non-return valve;
• the capacity and / or the shield have deformable profiles;
• the capacity profile has deformable curvatures or broken lines with or less an inflection point;
• the shield profile has deformable curvatures or broken lines with at least one point of inflection;
• the deformable profiles are likely to have either convex or concave parts;
• it includes a braking mechanism disposed at the outlet of the capacity;
• the braking mechanism consists of a skirt placed in the extension of the capacity;
• the braking mechanism comprises at least one annular part movable in rotation and associated with means capable of driving it preferably at adjustable speed;
• the annular part comprises a crown integral with at least one internal part of helical shape with at least one turn, the direction of rotation and the pitch of the helical part being adapted to the evacuation of solid fractions and not to their compression;
• the annular part comprises a crown integral with internal helical fins;
• the capacity is associated, in the axis of the latter, with a solid fraction evacuator constituted by a screw whose diameter is advantageously increasing in the upstream-downstream direction, means being provided to cause a relative rotational movement between the capacity and the screw;
• the outer edge of the screw is sharp;
• the capacity has longitudinal internal ribs;
• the shield is of the filtering type, that is to say pierced with holes for the passage of liquid fractions;
• the cross-section of the capacity and that of the shield is either circular or polygonal.

• La figure 1 est un graphique montrant comment se répartit la pression de retenue agissant sur un mélange à presser et considérée longitudinalement, respectivement selon l'état de la technique et selon l'invention.
• La figure 2 est un graphique montrant comment se répartit cette même pression de retenue considérée transversalement, respectivement selon l'état de la technique et selon l'invention.
• La figure 3 montre schématiquement comment s'orientent les fractions solides pendant le pressage.
• La figure 4 montre schématiquement comment s'orientent des fractions solides analogues à celles de la figure 3 mais, ici, dans un dispositif conforme à l'invention.
• La figure 5 est une vue schématique en coupe longitudinale d'un dispositif mettant en oeuvre le procédé conforme à l'invention selon un premier mode de réalisation qui prévoit que la pression d'entrée est obtenue en déplaçant la capacité de pressage par rapport à une pièce formant piston et maintenue immobile.
• Les figures 6 et 7 sont des vues schématiques en coupe montrant le dispositif de la figure 5 dans deux phases de fonctionnement.
• La figure 8 est une vue schématique du dispositif des figures 5 7, considérée en coupe selon la ligne VIII-VIII de la figure 5.
• La figure 9 est une vue schématique partielle montrant une variante de l'invention selon laquelle on prévoit un clapet de non retour entre la capacité de pressage et la cuve d'entrée.
• La figure 10 est une vue schématique partielle montrant un deuxième mode de réalisation de l'invention, selon lequel la force de retenue est créée par un bouclier à vis, jouant en outre le rôle d'évacuateur des fractions solides.
• Les figures 11 et 12 sont deux vues schématiques partielles montrant, dans deux phases de fonctionnement, un autre mode de réalisation de l'invention selon lequel la pression d'entrée est obtenue en déplaçant une pièce formant piston par rapport à la capacité de pressage maintenue immobile.
• Les figures 13 et 14 sont der vues schématiques partielles de deux variantes d'un mode de réalisation de l'invention selon lequel la zone correspondant à la sortie de la capacité ainsi que le bouclier de retenue sont susceptibles d'être déformés.
• La figure 15 est une vue schématique transversale de l'aval vers l'amont de la capacité et montrant que cette dernière et le bouclier ont une section polygonale.
• La figure 16 est une vue schématique partielle longitudinale, montrant un mécanisme de freinage fixe placé à la sortie de la capacité.
• Les figures 17 et 18 sont des vues schématiques partielles longitudinales de deux variantes d'un mécanisme de freinage rotatif placé à la sortie de la capacité.

The invention will be better understood from the description below made with reference to the accompanying drawing. Of course, the description and the drawing are given only by way of an indicative and nonlimiting example.

• FIG. 1 is a graph showing how the holding pressure acting on a mixture to be pressed and viewed longitudinally is distributed, respectively according to the prior art and according to the invention.
• FIG. 2 is a graph showing how this same holding pressure, distributed transversely, is distributed according to the state of the art and according to the invention, respectively.
• FIG. 3 schematically shows how the solid fractions orient themselves during pressing.
• FIG. 4 schematically shows how solid fractions similar to those of FIG. 3 are oriented, but here in a device according to the invention.
• Figure 5 is a schematic view in longitudinal section of a device implementing the method according to the invention according to a first embodiment which provides that the inlet pressure is obtained by shifting the pressing capacity relative to a part forming a piston and kept immobile.
• Figures 6 and 7 are schematic sectional views showing the device of Figure 5 in two operating phases.
• FIG. 8 is a schematic view of the device in FIGS. 5 7, seen in section along the line VIII-VIII in FIG. 5.
• Figure 9 is a partial schematic view showing a variant of the invention according to which a non-return valve is provided between the pressing capacity and the inlet tank.
• FIG. 10 is a partial schematic view showing a second embodiment of the invention, according to which the retaining force is created by a screw shield, further playing the role of evacuator of the solid fractions.
• FIGS. 11 and 12 are two partial schematic views showing, in two operating phases, another embodiment of the invention according to which the inlet pressure is obtained by moving a piston-forming part with respect to the maintained pressing capacity motionless.
• Figures 13 and 14 are der schematic partial views of two variants of an embodiment of the invention according to which the area corresponding to the output of the capacity as well as the retaining shield are liable to be deformed.
• Figure 15 is a schematic transverse view from downstream to upstream of the capacity and showing that the latter and the shield have a polygonal section.
• Figure 16 is a partial longitudinal schematic view showing a fixed braking mechanism placed at the outlet of the capacity.
• Figures 17 and 18 are partial schematic longitudinal views of two variants of a rotary braking mechanism placed at the outlet of the capacity.

Referring to Figure 1, we see how the pressure P1 varies from forces developed by various known mechanisms and acting on a mixture to be pressed, in a capacity, in the "upstream-downstream" direction of a pressing device c '' i.e. longitudinally from the input O to the output X of this device.

Curve A shows this variation in a known device: the pressure is first established at input 0 at a large value, then increases further and decreases regularly until output X where it is minimal.

Curve B shows the variation of this same pressure P1 according to the process according to the invention and it can be seen that at input 0 the pressure P1 is established at a relatively low value then increases regularly but slightly while remaining thus practically uniform up to the vicinity of the output X where it increases significantly to reach its maximum value.

By comparing these two curves, it can be seen that the distribution of the pressure P1 considered longitudinally is practically opposite in a device of known type and according to the method according to the invention since the maximum of the curve A is located in the vicinity of the inlet. 0 and its minimum at the output X while on curve B we see that the pressure P1 has a minimum value at the input O and maximum at the output X.

In FIG. 2, we see how the pressure P2 is distributed, considered this time transversely with respect to a pressing device and the end of a diameter of this device has been indicated by D1 and by D2 the end opposite of the same diameter.

Curve C shows the distribution of the pressure P2 in a device of known type and it can be seen that the pressure is maximum at the periphery while it is minimum in the central part x.

Curve D represents the distribution of the transverse pressure P2 with the method according to the invention and it can be seen that this curve D is exactly the opposite of curve C since the pressure P2 has minimum values at the periphery of the device and maximum values in the central part x.

In FIG. 3, we have shown the effects, in a known device, of the pressure P1 shown diagrammatically by an arrow and it can be seen that this pressure P1 is exerted from the inlet to the outlet, that is to say say in the "upstream-downstream" direction and in the same direction as the entry of the mixture to be pressed, symbolized by two arrows F1.

We have also schematized the general orientation of solid elements which, during the pressing operation, are, in the central part of this device, perpendicular to the pressure P1 while they gradually tilt towards the periphery where they are practically in a direction parallel to that of the pressure P1, that is ie perpendicular to the radial passages of the pressing device, orientation in which they positively seal the orifices of the walls and oppose the passage of the liquid fractions.

Figure 4 is a diagram similar to that of Figure 3 but corresponding to the implementation of the method according to the invention. It can be seen that a retaining force F2 is created at the center of the device and at its exit and is directed in the direction opposite to that of the arrow F1 indicating the direction in which the mixture to be pressed is introduced into the device . This retaining force F2 comes from the presence of a central conical shield located at the outlet of the device.

Here therefore, contrary to what is known, the direction of the force F2 is opposite to the direction of the arrow F1, since it is a retaining force. One might think that this retaining force comes directly from the resistance opposed by the central shield, but the reality is more complex because, after an initial start-up phase, the solid fractions accumulate in "cake" or "roll" in front the shield and the mixture to be pressed is compressed not directly on the shield but on the cake. In a vegetable matter press, there are therefore two states of the mixture to be pressed: at the inlet, the mixture is in its natural state and at the outlet the dry (or pseudo-dry) matters are strongly compressed and hard. Between these two extreme states are intermediate states. The retaining force F2 and the pressure P1 are indeed antagonistic, according to the method according to the invention, but the retaining force F2 is caused by the exit resistance of the cake. Of course, this resistance comes from the presence of the shield, but it only acts against the pressure P1 indirectly, with the interposition of the cake.

It follows from this arrangement shown diagrammatically in FIG. 2, that the pressure P1 having a maximum value in the center and minimum at the periphery, the solid particles remain practically oriented perpendicular to the force F2, including at the periphery, so that 'They are oriented in the direction most favorable to the extraction of liquid fractions.

Referring now to Figure 5, we see an example of the structure of a device implementing the method according to the invention.

This device includes a hopper 1 for loading a heterogeneous mixture and in the following description we will take as an example the grapes harvested to be pressed to give a juice as clear as possible providing, after treatment such as fermentation or distillation, an alcoholic drink , especially wine or Cognac.

The hopper 1 opens into a tank 2 in the shape of a bucket, that is to say with a bottom of circular section and with divergent planar walls. In this tank 2 extends an endless screw 3, the axis 4 of which is held by a bearing 5 and is connected to a motor for rotating 6.

The walls of the hopper 1 and of the tank 2 are perforated in order to allow the dripping juices collected to pass through an envelope 7 which surrounds the hopper 1 and the tank 2 and which has a discharge orifice 8.

At its end opposite to that which is close to the motor 6, the screw 3 comprises a second thread 9, just like the main thread and which ends in being diametrically opposite to it and both in a plane 10 perpendicular to axis 4, in order to form an obstacle to the return of mixture in the tank 2, from downstream to upstream, as will be explained below.

It is noted that the diameter of the screw 3 is constant inside the tank 2 and decreases in line with a socket 11 whose interior is frustoconical and which thus has a circular central passage 12 of diameter less than the cross-section of the tank 2 and an annular part 11 co-planar with the plane 10, this assembly having to play the role of piston.

A solid central part could also be provided around which an annular passage would be provided for the transfer of the mixture by the screw 3.

Next to the socket 11, there is a capacity 14 of frustoconical shape whose small base is close to the socket 11 and constitutes the inlet of the capacity 14 and whose large base, opposite to the previous one, constitutes the outlet of the fractions solid. In other words, the diameter of the capacity 14 increases in the "upstream-downstream" direction, that is to say in the direction of the entry of the mixture towards the exit of the solid fractions.

The walls of capacity 14 are perforated so that the liquid fractions separated from the solid fractions introduced and pressed into capacity 14 can pass therethrough.

In FIGS. 5 to 7, the perforations of the capacity 14 are shown in the form of slots 15 resulting from intervals between solid parts 16 held together by external circular reinforcements 17 giving the assembly the rigidity of a structure complete. In practice, a different structure can be used, in particular a grid made of perforated sheet metal with oblong openings of major axis parallel to the axis of the capacity 14, this grid being of the type known per se. We know that in this case the grid must be held rigidly in the radial direction to resist the thrust of the pressed mixture and, for this purpose, reinforcements of the type of those shown here, 17 can be used.

The capacity 14 includes a cylindrical extension 18 whose internal diameter corresponds to the external diameter of the sleeve 11 by providing for the interposition of seals and / or members facilitating the sliding of the extension 18 on the sleeve 11, or avoiding the effects of friction metal against metal, these elements being generally designated by the reference 19.

On the fixed hopper 1-tank 2-casing 7 assembly is fixed an external flange 22 to which two longitudinal sections 23 and 24 are subjected.

On the circular reinforcements 17 of the capacity 14, sot fixed side members 25 and 26 supporting profiles 27 and 28 extending inside the profiles 23 and 24.

Between sections 23 and 27 on the one hand, 24 and 28 on the other hand, there are interposed rotating rollers 29 ensuring the frictionless guiding of the internal profiles 27 and 28 in the external profiles 23 and 24.

Cylinders 30 and 31 are provided inside the profiles 27 and 28 in order to be able to move the capacity 14 relative to the co-planar parts 10 and 11 forming the piston.

To this end, the body 32 of the actuator 30 is fixed by an eyelet 33 and a flange 34 to the profile 23 while the rod 35 of the actuator 30 is connected by an eyelet 36 and a flange 37 to the profile 27.

Symmetrically, the body 38 of the jack 31 is fixed by an eyelet 38 and a flange 40 to the profile 24 while the rod 41 of this jack 30 is fixed by an eyelet 42 and a flange 43 to the profile 28.

The cylinders 30 and 31 are of the double-acting type and therefore have fluid inlets 44-45 and 46-47 respectively controlled by solenoid valves, as is known per se, to cause the extraction of the rods 35 and 41 or their retraction.

The downstream end of the capacity 14 is entirely open and allows the establishment of a central conical shield 50 associated with radial coulters 51 and integral with an axial rod 52 slidably mounted in a guide 53.

The shield 50 is associated with an articulated diamond 54 of which two opposite vertices 55 and 56 are connected to a jack 57, respectively to the body 58 and to the rod 59 thereof, while the other two opposite vertices 60 and 61 are connected respectively at a fixed point and at the rod 52.

This jack 57 contains a pressurized fluid and acts as a shock absorber and it is advantageous to be able to adjust the passage section of an inlet 62 and an outlet 63, by any known means, to adjust the value of the resistance that the jack 57 opposes to the forces exerted on it by the conical shield 50, itself subjected to the thrust of the mixture.

The guide 53 is fixed to a crosspiece 64 joining two supports 65 and 66 integral with the capacity 14.

• On introduit dans la trémie 1 le mélange à séparer selon la flèche F3 (figure 6), de sorte qu'il tombe dans la cuve 2 où il s'égoutte, et entre les spires de la vis 3, celle-ci étant entraînée en rotation par le moteur 6 pour déplacer le mélange d'amont en aval et l'introduire dans la capacité 14 par l'ouverture centrale 12.

The operation of the device which has just been described is as follows:

• The mixture to be separated is introduced into the hopper 1 according to the arrow F3 (FIG. 6), so that it falls into the tank 2 where it drips, and between the turns of the screw 3, the latter being driven in rotation by the motor 6 to move the mixture from upstream to downstream and introduce it into the capacity 14 through the central opening 12.

Note that the rotation of the screw 3 does not cause significant pressure but a simple compaction due to the internal frustoconical shape of the sleeve 11

When the mixture reaches capacity 14, it fills it naturally as new fractions of mixture are introduced into capacity 14 by the worm 3.

At the time of filling, the jacks 30 and 31 were ordered so that the capacity 14 is in the position shown in FIG. 6 according to which the cylindrical part 18 completely covers the sleeve 11 so that the capacity 14 has a minimum volume.

In this position, the pressures in the pressurized fluid lines 44, 45, 46 and 47 are canceled, so that the jacks 30 and 31 are neutral.

The capacity 14 moves from upstream to downstream under the effect of the arrival of the mixture which pushes it, this "decline" in the capacity giving way to new arrivals of mixture. It should be noted that here there is only a simple push and not a compression since the capacity 14 moves effortlessly and since no force is developed against the arrival of the mixture. When the capacity 14 reaches the end of its travel, the admission of pressurized fluid into the jacks 30 and 31 is controlled by the inputs 44 and 46, in order to move the capacity 14 in the direction of the arrows F5 (FIG. 7), towards its position of minimum volume, which has the effect of driving the shield 50 in the same direction by the supports 65 and 66 and by the cross-member 64, the cylindrical part 18 sliding on the cylindrical external part of the sleeve 11.

For its part, the jack 57 acts in the direction of the approach of the vertices 55 and 56 of the rhombus 57, that is to say the spacing of the vertices 60 and 61, the rod 52 thus having a tendency to push the shield 50 towards the interior of the capacity 14, in the downstream-upstream direction. The shield 50 thus opposes the free exit of the mixture.

The displacement of the capacity 14 relative to the fixed sleeve 11 therefore causes the compression of the mixture fraction between on the one hand the wall 13 and the plane 10 coplanar and on the other hand. the central shield 50 with the interposition of the dense cake already formed. The wall 13 and the plane 10 constitute in a way a piston on which the mixture is pressed thanks to the action of the jacks 30 and 31, this pressure causing the exit of the liquid fractions by the slots 15 of the capacity 14 while the fractions solids accumulate in a dense cake downstream of the capacity 14. When the cake reaches a degree of dryness determined by the adjustment of the pressure in the jack 57, it is forced against the coulters 51 which fragment it into parts which exit the device according to arrows F6, through the annular passage.

For its part, the shield 50 undergoes two opposing forces c the thrust of the cake in the direction of the arrows F4 (FIG. 6) and the resistance of the jack 57. When the solid fractions of the mixture, after extraction of the liquid fractions, have agglomerated into cake, it acts strongly on the shield 50 which can retreat against the jack 57, until a balance is established determined by the adjustment of the pressure in the jack 57. When the thrust of the cake increases , the shield 50 moves back a little and, given its shape, correlatively enlarges the passage section offered at the outlet of the solid fractions, section determined by the width of the annular passage which remains between the outside of the cone 50 and the inside of capacity 14.

This results in pressure regulation resulting exerted on the mixture, from the setting operated on the cylinder 57 and by which we can modulate the pressing action to obtain the desired percentage of liquid fraction compared to solid fractions. In other words, the position of the shield 50 determines the passage section, the intensity of the retaining force and the residual moisture content in the cake, that is to say the value of the "pressed" .

To absorb the forces transmitted to the jack 57 by the shield 50, and in particular the vibrations and shocks, it is possible to insert a spring 67 suitably calibrated on the rod 52, between the rear face 50a of the shield 50 and the fixed guide 53 (FIG. 5 ).

It is noted that the compression of the mixture inside the capacity 14 is obtained by a simple linear movement in which the screw 3 does not intervene in any way by its rotary function since on the one hand it is stopped during the pressure phase and that on the other hand the mixture of the capacity 14 practically does not reach it thanks to the plane 10. It should be noted that with this embodiment, the pressure is not exerted from upstream to downstream but from downstream to upstream , according to arrows F5.

The endless screw 3 therefore only plays here the role of a material transport mechanism and could therefore be replaced by any other device if it turns out to be more practical than a worm.

Thanks to the frustoconical shape of the capacity 14 the mixture moves from upstream to downstream, from the small base to the large, which eliminates the phenomenon of rasp and friction and which allows a better flow of the mixture as well as the total absence of trituration, the solid particles being oriented as shown in FIG. 4, as explained above. Of course, the section of the capacity 14 could be other than circular, for example oval.

The increase in pressure shown diagrammatically by curve B in FIG. 1 is obtained by the conical shield 50 and the jack 57 which is associated with it. The shapes and dimensions of the shield 50 can be adapted to different conditions of use. In all of these, the shield 50 being situated in the axis of the device, it is indeed in the center that the pressure P1 is the strongest and it is indeed towards the periphery that it decreases since the outlet is of annular shape .

The different possibilities of intervention both in the original dimensioning and in the adjustments during operation, allow a homogeneous and increasing distribution of the compression forces, distribution which prevents the bursting of solid particles and the trapping of the juices in the solid materials, whereby it is possible to use pressures lower than those which are necessary with the known devices.

By giving the cone 50 a fairly tapered shape from its top and then significantly increasing the flare, as shown in Figure 5, we obtain a passage section which decreases gradually and then more suddenly, which correlatively creates a force restraint increasing slightly then more strongly to cause efficient extraction of the liquid fractions at the end of the cycle.

The drying of the mixture is thus modulated according to the pressure which prevails in the jack 57 and, therefore, according to the retaining force of the shield 50.

Naturally, the various functions can be ensured by means of an automatic control center informed from limit switches, contactors, probes, pressure gauges, etc.

To avoid any return of mixing of the capacity 14 towards the tank 2 when the capacity 14 is moved in the direction of the arrows F5, a non-return valve can be provided as shown in FIG. 9.

The bush 11 and its front part 13 as well as its central passage 12 by which the mixture is introduced into the capacity 14 are shown diagrammatically in this figure.

The non-return valve is composed of a shutter 70 of diameter equivalent to that of passage 12 and provided with peripheral reliefs 71 by which it abuts against the front part 13 when it receives a pressure directed in the direction of the arrows F5, position in which the passage 12 is completely closed.

The shutter 70 is capped by a retaining piece 72 comprising arms 63 fixed to the part 13 and curved towards a common center 74 against which the shutter 70 is placed in abutment when it receives a pressure directed in the direction of the arrows F4, that is to say when the screw 3 is rotated and pushes the mixture through the central passage 12.

In Figure 10, there is shown a variant of the means used to ensure the evacuation of solid fractions.

Note that the conical shield 50 is removed and replaced by a central endless screw 80 of increasing diameter in the upstream-downstream direction and secured to a shaft 81 rotatably mounted in a retaining bearing 82 and connected to a setting mechanism. movement of any known type such as a gear motor 83.

When the screw 80 is held stationary, it leaves only a narrow and strongly resistant helical passage which opposes the exit of the solid fractions agglomerated into a cake. To ensure the proper outlet of these solid fractions, it is therefore necessary to drive the screw 80 in rotation but in the opposite direction to that which would cause compression and it actually constitutes an evacuator of the solid fractions when the mixture is pressurized by a translational movement, as described above.

The evacuation of the solid fractions can be modulated by varying the speed of the screw 80 to ensure a very precise adjustment and an excellent suitability of the device and of the mixture which is available in all circumstances.

The percentage of solid fractions compared to port to the evacuated liquid fractions therefore depends on the speed of rotation of the screw 80.

We find the coulters 51 which have the effect of slicing the solid fractions to facilitate their evacuation.

When the screw 80 is rotated, it could have the effect of driving the solid fractions still located in the capacity 14 and to avoid this rotation preventing the free exit of the solid fractions, it is possible to provide inside the capacity 14 longitudinal ribs 85 to which the various components of the mixture hang, thus preventing their entrainment by the screw 80.

It is good that the screw 80 has a variable pitch, in the direction of a decrease, from its upstream end towards its downstream base because along the screw 80 the volume of the mixture decreases further and it must be saved less space. The pitch of the screw 80 is then greater where the turns have a small diameter and its pitch is smaller where the turns have a larger diameter.

In order to allow easy removal of the solid fractions and in particular to avoid clogging due to their attachment to the hub and to the turns of the screw 80, the latter can be given an acute profile so that their outer edge 80a is sharp.

Note that the bearing 82 is integral with a crosspiece 64 and supports 65 and 66, as in the case of Figures 5 to 7 so that the capacity 14 and the screw 80 are made integral in translation. Their relative position can be adjusted according to the nature of the mixture to be treated. For this, two series of holes 68 are provided on the supports 65 and 66 and holes 69 on the crosspiece 64 in order to choose those which will be placed opposite for the passage of assembly bolts. This presetting is carried out according to the characteristics of the mixture to be treated. In the case of grapes, we may wish a different pre-setting for the first harvest and for those at the end of the campaign for example.

The screw 80 is only rotated when the mixture introduced into the capacity 14 is pressurized (the screw 3 being stopped) by deployment of the jacks 30 and 31. It is stopped when the jacks 30 and 31 are neutralized and that of the mixture is introduced into the capacity 14, the screw 3 then being in rotation.

As is known per se, it is good to provide a so-called "shutter" clover 90 which is freely mounted on an axis 91 and which opposes the winding of the mixture around the axis 4.

In the vicinity of the outlet of the solid fractions (FIG. 10), it is also possible to have circular coulters 92 which cause the cutting of the cake or "sausage" of dry materials and thereby facilitate its evacuation by the annular outlet, according to the arrows F6 of Figure 7.

It is also possible to use shutter clovers (not shown) associated with the screw 80 to prevent the winding of materials around its axis and also acting as coulters.

Referring now to FIG. 11, we see an embodiment according to which the relative linear movement between the capacity 14 and the "piston" no longer comes from the displacement of the capacity 14 relative to the assembly 10-12- 13 fixed but on the contrary of the movement of a piston assembly with respect to the fixed capacity 14.

We see that the axis 4 of the screw 3 is hollow and receives freely, that is to say without friction and a fortiori without blocking, a shaft 100 carrying a screw thread 101 corresponding to the thread of the screw 3 and located in its extension. There is shown a simplified arrangement according to which there is no frustoconical sleeve 11 and, therefore, it is assumed that the thread of the screw 3 as the thread 101 have a constant diameter and are both equal. In reality, the thread 101 may correspond to the end of the screw 3 as shown in FIG. 5.

The screw 3 has only one thread, while the shaft 100 carries a second thread 102 of the same pitch and the two threads 101 and 102 are shaped at their end as has already been described for the screw 3 opposite of Figure 5, that is to say that they end in a common plane 103 substantially perpendicular to the axis of the assembly.

The shaft 100 has a peripheral groove 104 which extends over a certain length and which is engaged with a motor 105 of any type known per se to drive the shaft 100 in rotation when it is started.

Opposite the free end of the shaft 100, there is a double-acting cylinder 106 whose rod 107 is subject to the shaft 100 and whose body 108 is connected to two pressurized fluid lines 109 and 110.

• Pour que du mélange soit introduit dans la capacité 14, on met en marche simultanément les moteurs 6 et 105 afin que l'axe 4 et l'arbre 100 soient tous deux entraînés en rotation (le moteur 105 entraînant l'arbre 100 par la cannelure 104) et que les filets 3, 101 et 102 se comportent comme s'ils étaient solidaires. Dans cette situation, le vérin 106 est alimenté en fluide sous pression pour que sa tige 107 et l'arbre 100 soient dans leur position rétractée représentée sur la figure 11.

The operation of this device is as follows:

• For the mixture to be introduced into the capacity 14, the motors 6 and 105 are started simultaneously so that the axis 4 and the shaft 100 are both rotated (the motor 105 driving the shaft 100 by the groove 104) and that the threads 3, 101 and 102 behave as if they were integral. In this situation, the jack 106 is supplied with pressurized fluid so that its rod 107 and the shaft 100 are in their retracted position shown in FIG. 11.

This operating phase corresponds exactly to what has been described above and the details of its consequences on the mixture to be pressed will therefore not be repeated.

When the mixture has to be compressed, the engine 105 is stopped only so that the shaft 100 is immobilized in rotation, unlike the axis 4 which continues to rotate, the mixture introduced into the hopper 1 continuing to be pushed from upstream to downstream. Simultaneously, the supply of the jack 106 is reversed so that its rod 107 is extracted and pushes the shaft 100. The threads 101 and 102, by their co-planar parts 103 then act like a piston in the stationary capacity 14 and cause the pressing of the mixture as described above, the device being in the position shown in FIG. 12. When the desired pressure is reached (and sensed for example by manometers), the cylinder 106 is neutralized and the motor 105 is restarted, still in engagement with the groove 104 thanks to the length of the latter, but at a speed such that the shaft 100 rotates more fast as the axis 4, and in the same direction, so that the threads 101 and 102 somehow "screw" into the mixture present behind them under the uninterrupted action of the thread 3, and go up axially to that the shaft 100 has found the position it occupies in Figure 11. The cylinder 106 is again supplied to push the threads 101 and 102 and the cycle begins again. It is noted that the drive of the shaft 100 by the motor 105 occurs regardless of the axial position of this shaft 100 and even during its sliding inside the axis 4.

In the upstream-downstream direction, the shaft 100 is pushed by the cylinder 106 but in the downstream-upstream direction it is brought back by the rapid rotation imparted to it by the motor 105. We can therefore be satisfied with a single cylinder 106 effect.

To avoid the entry of materials into the hollow axis 4, a cable gland 111 is provided on its free end which can also serve as a support and guide for the shaft 100 if the latter does not slide exactly in the axis 4.

It is important to note that the shaft 100 and the screw threads 101 and 102 that it carries are absolutely independent of the action of the screw 3, as much in rotation as in speed or in sliding. This is why this device does not have any of the drawbacks mentioned in the preamble to this description and, on the contrary, provides marked advantages.

This embodiment provides that the capacity 14 is stationary and that the relative movement between it and the piston is caused by sliding of the latter, unlike the embodiment of FIGS. 5 to 7.

In practice, we can choose the mobile piston solution for small installations and the mobile capacity solution for heavier installations.

With the embodiment according to which the capacity 14 is stationary and the "piston" mobile, the latter can no longer be produced only with a central part such as 10 but with the whole of the socket 11 so that the compression effect occurs over the entire diameter of the small base of the capacity 14. This variant is particularly suitable for the case where a non-return valve 70 is prevented, as an example has been described with reference to FIG. 9.

Referring now to Figures 13 and 14, we see two variants of an embodiment which allows to take into account the different densities and difficulties that can be found in certain circumstances, for example: grape must in high degree sweet and very hot at harvest temperature, do not create stability of the solid fractions at the outlet of the capacity, stability favorable to the proper functioning of the device.

In other circumstances, certain materials to be pressed require a release of the internal pressure of the material in the capacity before a final over-press.

According to the invention, a regular and maximum progressive pressure is obtained at the end of the capacity over all of the material therein, but according to what has just been described, the particularly sensitive zone situated where contact occurs with the material to be pressed at the end of capacity and in the annular space at the outlet of the filter tube. It therefore seems useful to intervene and control these circumferential zones in order to avoid an escape of unpressed materials at the periphery of the solid materials already pressed at the center.

With the embodiment of Figures 13 and 14, it makes changeable and adjustable the shape of the capacity in the vicinity of its outlet end as well as the shape of the shield, in particular to be able to vary the taper of the latter.

In FIGS. 13 to 18, the same elements as those already described have the same references but in the order of hundreds (example: 140 for the capacity 14, 500 for the shield 50, etc.).

In FIG. 13, the capacity 140 and the shield 500 have surfaces with curved generatrices. A co-ordinated position of these two elements has been shown in solid lines. By applying to the capacity 140 a force directed towards its virtual axis, for example by means of cylinders 1000 regularly distributed, it can be given a narrowed shape represented in dotted lines, because this part of the capacity 140 is produced on the outlet side in a material deformable.

By acting on the jacks 1000, these shapes are adjusted to give the dry material outlet section an adjustable value.

It is the same for the shield 500 with which cylinders 2000 is associated. Only main cylinders have been shown because the number and the arrangement of these are within the reach of those skilled in the art.

By acting on the cylinders 1000 and on the cylinders 2000, it is not only possible to vary the passage section overall but by zones. One can, for example, give the shield 500 a smaller section downstream of a larger section to cause in the pressed material a pressure drop during its movement from upstream to downstream.

In FIG. 14, a variant is shown according to which the shapes of the capacity 140 and of the shield 500 are no longer curved but in broken lines and, therefore, have lines of inflection 141 and 142, 501, 502 and 503.

By acting on the cylinders 1000 and 2000, it is possible to give the output of the capacity 140 a section which is either variable, narrowing or increasing, or a constant section.

Naturally, the jacks 1000 and 2000 constitute only one of the means likely to be used, the main thing being to be able to cause a constriction of the outlet section, either by narrowing the capacity 140, or by extension of the shield, either by these two operations at the same time.

This can be simplified if the capacity section 140 and / or that of the shield 500 are not circular but polygonal, as shown in Figure 15.

We see here that the capacity 140 has the shape of a six-sided pyramid trunk whose small base, located upstream side, is limited by the wall 130 in which is provided the central opening 120 for the introduction of the material to be pressed and whose large base is open since it constitutes downstream the outlet of the solid materials. The shield here has the shape of a six-sided pyramid.

All polygonal sections are possible, including square and rectangular, as long as an inlet section (wall 130) of lesser extent than that of the outlet section is kept.

In FIG. 16, it can be seen that in the annular passage delimited by the base of the capacity 140 and by the shield 500, there is a skirt 3000 of substantially circular section. As it extends the capacity 140 in line with the shield 500, it has the effect of reducing the outlet section.

Its braking effect is amplified by beads 3001 and 3002.

As the skirt 3000 can be useful in certain cases and useless, even harmful, in others it is good that it is removable. For this, provision is made here for it to be fixed to supports 650 and 660 by bolts 3003 engaged in lug holes 3004 and in holes in said supports 650 and 660.

FIG. 17 shows another embodiment of the braking mechanism according to which this mechanism comprises, instead of a fixed skirt 3000, a rotary skirt 4000 carrying turns 4001 and integral with an outer crown 4002 engaged with a pinion 4003 of a 4004 gear motor.

The rotary skirt 4000 carries rollers 4005 all mounted on their axis and engaged with an annular guide 4006 fixed to the supports 650 and 660 by bolts 4007.

The braking effect is obtained by giving the skirt 4000 an appropriate speed of rotation, it being recalled that the turns 4001 are oriented so that the rotation of the skirt 4000 has the effect of extracting the solid fractions and not to compress them. There is therefore always braking but it is all the stronger when the rotation of the skirt 4000 is slow.

The rollers 4005 and the guide 4006 can be replaced by any other, equivalent, in particular with bearing surfaces made of anti-friction material.

FIG. 18 represents a variant according to which the rotary skirt 4000 is provided with a plurality of fins 4008.

When the mixture to be pressed is admitted into capacity 140, the braking mechanism is stopped. When the capacity 140-shield 500 assembly is set in translational movement to press the mixture against the wall 130, the rotary skirt 4000 is rotated at a given speed, preferably adjustable, so that the solid pressed fractions can leave the capacity 140. By adjusting the speed of rotation of the skirt 4000, the braking is adapted to the characteristics of the mixture to be treated and the output of the pressed fractions is regulated.

It emerges from the above description that the method according to the invention, implemented by a corresponding device, causes a maximum retaining force at the outlet of the mixture and not a pushing pressure at the inlet, contrary to what which occurs through the implementation of known methods and devices.

The resulting good orientation of the solid fractions considerably reduces the resistance to extraction of the liquid fractions.

The invention is particularly applicable to the pressing of grapes, but can also be used for pressing other industrial or natural products. Among these, there may be mentioned olives, certain seeds, etc.

The invention can also be applied to the production of small household presses for obtaining fruit, citrus or vegetable juices, including for obtaining volumes as small as the juice of a single orange or than the volume of a single glass. In this case, provision can be made for the shield to be of the filtering type, that is to say pierced with passages to allow the exit of liquid fractions still present downstream of the capacity.

The realization of such small devices is accomodated by simplifications, in particular for the realization of the retaining force which can be done without adjustment means or, at the very least, with simpler means than the diamond 54 and the cylinder 57 for example. These simplifications come not only from the change in dimensions but also from the change in operation because if the pressing is done continuously, it is necessary, as described, to provide a permanent and coordinated retaining force to the also permanent evacuation of the solid fractions; if the operation is punctual for one or a few fruits, the retaining force can be constant and independent of the evacuation which will be carried out, for example, at the end of pressing in one go.

Claims (24)

1. A method of separating, by pressing intimately combined liquid and solid fractions in the form of a heterogeneous mixture, such as for example, juices, pulps, kernels, pips stalks and vegetable elements of fruit such as harvested grapes, of the type in which a vessel (14) comprising sidewalls traversed by narrow passages (15) is charged in a so-called "upstream-downstream" direction via a so-called input end with heterogeneous mixture, then the infeed of mixture is interrupted, then a pressing action is induced by effecting a relative linear displacement between the vessel (14) and a non-rotary element (10-13, 103) forming a piston situated before the input end so that this element (10-13, 103) penetrates into the volume (14) from upstream to downstream, characterised in that an opposing retaining force, that is to say directed from downstream to upstream co-axially with the vessel (14), is engendered at its so-called outlet end opposite the preceding end and acting on the fractions of heterogeneous mixture fed in, which are thus agglomerated progressively into a cake of solid fractions, whilst forming an annular outlet space, also coaxial, whereupon after the pressing of the heterogeneous mixture simultaneously causing the emergence of at least a part of the liquid fractions through the walls of the vessel (14) and the discharge of a part of the cake of solid fractions through the outlet space, the relative linear displacement is then stopped, after which a renewed input of mixture is effected and its pressing in the vessel (14) is effected at a pressure matched to the value of the outlet retaining force and so on in successive cycles.

2. A method according to claim 1, characterised in that to effect the pressing the vessel (14) is held still and the element (103) forming a piston is displaced in the upstream-downstream direction in an axial sliding displacement with respect to the said volume (14).

3. A method according to claim 1, characterised in that the pressure in the vessel (14) and the opposed retaining force are matched to establish within the said vessel (14) a pressure rising slightly from the input end to a section situated in the vicinity of the outlet end, beyond which section an appreciable increase in the retaining force is effected.

4. A device for operating the method of the claims 1 to above, of the type comprising a vessel (14) the sidewalls of which are traversed by narrow passages (15) and which has two open and opposed ends of which the so-called "input" end is placed in alignment with an element (10-13) forming a piston and provided with an opening (12) for the input of mixture into the vessel (14), characterised in that the vessel has a cross section increasing from upstream to downstream and in that the device comprises a shield (50-80-500) associated with the other end designated "outlet", the assembly of the vessel (14) and the shield (50-80-500) being mounted movably relative to the element (10-13) forming a piston, in order to press the substance against the shield (50-80-500) at which are produced cakes of solid fractions which are thereafter to be discharged around the shield (50-80-500).

5. A device according to claim 4, characterised in that the shield (50) is arranged to be resiliently displaceable in the longitudinal direction of the vessel (14) to leave in being an annular co-axial passage of greater or lesser size for discharge of the solid fractions, means (30-31) being provided for effecting a relative linear displacement between the volume (14) and the element (10-13) forming a piston.

6. A device according to claim 4, characterised in that the element forming a piston is constituted by a front wall (13), a hollow sleeve (11) which is situated at the end of a vat (2) provided with a hopper (1) for the input of heterogeneous mixture and which is associated with an axial rotary screw (3) situated in alignment with an opening (12) traversing the front wall (13) of the sleeve (11) at its centre, this screw (3) being shaped so as to present, at its extremity, at least a part (10) substantially at right angles to the axis (4) of the screw (3).

7. A device according to claim 6, characterised in that the element (11-13) is movably mounted, whereas the vessel (14) is stationary.

8. A device according to claim 5, characterised in that the element forming a piston comprises at least one screw-thread (101-102-103) which is independent and dynamically coupled to two separate mechanisms (105 and 106) able to drive it alone, in rotation and in an axial displacement respectively, and the end of which is shaped so as to present at least one part (103) substantially at right angles to its axis.

9. A device according to claims 5 and 8, characterised in that the axis (4) of the screw (3) is hollow and is freely traversed by a shaft (100) carrying the screw thread (101-102) which is thus situated in the extension of the screw (3), this shaft (100) being coupled to the mechanisms (105 and 106) able to drive it respectively in rotation and in axial displacement, independently of the shaft (4) of the screw (3).

10. A device according to claim 6, characterised in that the front wall (13) has a central opening provided with a non-return valve (70-74).

11. A device according to claim 4, characterised in that the vessel (140) and/or the shield (500) have deformable sections.

12. A device according to claim 11, characterised in that the outline of the vessel has deformable curvatures or broken lines with at least one point of inflexion.

13. A device according to claim 11, characterised in that the outline of the shield has deformable curvatures or broken lines with at least one point of inflexion.

14. A device according to claim 11, characterised in that the deformable sections are able to present either convex or concave parts.

15. A device according to claim 4, characterised in that it comprises a braking mechanism (3000) situated at the outlet of the vessel (140).

16. A device according to claim 15, characterised in that the braking mechanism is formed by a skirt arranged in the extension of the vessel.

17. A device according to claim 15, characterised in that the braking mechanism comprises at least one rotationally movable annular part associated with means adapted to drive it, preferably at an adjustable speed.

18. A device according to claim 17, characterised in that the annular part comprises a crown integral with at least one internal helically shaped element having at least one turn, the direction of rotation and the pitch of the helical element being adapted for discharge of the solid fractions and not for their compression.

19. A device according to claim 18, characterised in that the annular part comprises a crown integral with internal helical blades.

20. A device according to claim 4, characterised in that the vessel (14) is associated, in the axis of this latter, with a solid fraction ejector formed by a screw (80) the diameter of which advantageously increases in the upstream-downstream direction, means (81 to 83) being provided for effecting a relative rotational displacement between the vessel (14) and the screw (80).

21. A device according to claim 20, characterised in that the outer edge (80a) of the screw (80) is sharp.

22. A device according to claim 4, characterised in that the vessel (14) has longitudinal internal ridges (85).

23. A device according to claim 4, characterised in that the shield (50) is of the filtering type, that is to say is pierced by holes for the passage of liquid fractions.

24. A device according to claim 4, characterised in that the cross-section of the vessel and of the shield is either circular or polygonal.

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