EP4205856A2 - Product transfer system - Google Patents

Abstract

The present invention relates to a system (10) for transferring product, in particular in a vacuum treatment chamber, said transfer system (10) comprising:- a body (12) delimiting a cavity (14), and- a wheel (20) housed in said cavity (14) and provided with at least one pocket (28) at its periphery, the wheel (20) being adapted to rotate so as to bring product from said inlet zone (A ) to said dispensing area (D), wherein the transfer wheel (20) and the body (12) cooperate to form a substantially airtight barrier between the two areas (A, D). The invention also relates to a processing system including such a transfer system and a corresponding processing method.

Description

Technical area

The present invention relates to the vacuum treatment of products, in particular products in powder form.

It relates in particular to a system for such treatment, in particular but not limited to a vacuum grinding system.

State of the art

Grinding systems are commonly used in the food or pharmaceutical industry. The grinding chamber, in which the product is ground, is advantageously put under vacuum to avoid altering the qualities of the product by oxidation.

Vacuum grinding systems are already known, for example of the document FR 2 628 007 . But these systems do not make it possible to obtain a satisfactory yield or do not make it possible to avoid a certain oxidation of the product, which alters its essential qualities.

The applicant has recently developed a continuous vacuum grinding system, operating by means of an entry and exit airlock system which can be placed under vacuum and controlled by valves. The control of the valves makes it possible to transfer a quantity of product to be ground into the grinding chamber, which is permanently kept under vacuum. However, this system has the disadvantage of being relatively bulky.

The object of the present invention is to propose an alternative system to the aforementioned system, which makes it possible to treat the product continuously and in a medium maintained under vacuum throughout the treatment operation.

Disclosure of Invention

The idea underlying the present invention is to take advantage, for the management of the vacuum in a treatment chamber, of the product dispensing member typically implemented in such a room. The treatment chambers are in fact provided, most of the time, with distribution members of the rotary or other type, making it possible to supply the treatment devices contained in said chambers in a regular and homogeneous manner. However, these distribution members play no role in managing the pressure inside the chamber.

• un corps délimitant une cavité s'étendant dans une direction principale, et
• une roue de transfert logée au moins partiellement dans ladite cavité et séparant dans ladite direction principale une zone d'admission de produit et une zone de distribution de produit, la roue de transfert étant munie d'au moins une poche à sa périphérie et étant adaptée pour tourner autour d'un axe sensiblement orthogonal à ladite direction principale de sorte que ladite poche amène du produit depuis ladite zone d'admission jusqu'à ladite zone de distribution,

le système de transfert étant caractérisé en ce que la roue de transfert et le corps coopèrent pour former une barrière sensiblement étanche à l'air entre la zone d'admission et la zone de distribution.According to a first aspect, the invention relates to a system for transferring product, in particular for transferring product into a vacuum treatment chamber, the transfer system comprising:

• a body defining a cavity extending in a main direction, and
• a transfer wheel housed at least partially in said cavity and separating in said main direction a product intake zone and a product distribution zone, the transfer wheel being provided with at least one pocket at its periphery and being adapted to rotate around an axis substantially orthogonal to said main direction so that said pocket brings product from said intake zone to said dispensing zone,

the transfer system being characterized in that the transfer wheel and the body cooperate to form a substantially airtight barrier between the intake zone and the distribution zone.

Here, cooperating to form a substantially airtight barrier means that the maximum air flow between the intake zone and the distribution zone (between the wheel and the body) is less than or equal to 200 normal liters per minute (Nl/min), preferably less than or equal to 150 normal liters per minute (Nl/min), even more preferably less than or equal to 100 normal liters per minute (Nl/min).

To measure this maximum flow, it is possible, for example, to close the distribution zone and create a vacuum there using a pump, and at the same time measure with a flow meter, in the intake zone, the quantity of air sucked through the impeller by the effect of the vacuum pump.

The passage of air between the intake zone and the distribution zone is substantially prevented or limited, so that a pressure difference between the two zones can be kept substantially constant or, at the very least, can vary in sufficiently low proportions to be compensated by the use of a vacuum pump for example.

The transfer system according to the invention is for example particularly suitable for closing the entrance to a treatment chamber. The distribution zone then corresponds to the interior of said treatment chamber, which is advantageously under vacuum, in particular at an absolute pressure of between 0.05 and 0.3 bar. In this case, the inlet zone typically contains the product to be treated and, advantageously, forms the interior of a reservoir of product, with the absolute pressure inside said reservoir typically equal to atmospheric pressure. In the context of such use, the transfer system allows the continuous supply of the treatment chamber, while guaranteeing the substantial maintenance of the pressure differential between the tank and the treatment chamber and therefore of the vacuum inside. of said processing chamber. As indicated previously, a slight air leak between tank and treatment chamber is not detrimental if it can be compensated for by implementing a vacuum pump in the treatment chamber. Preferably, however, the maximum flow of air between the two zones is minimized as much as possible, or even rendered zero.

The main direction of the transfer system corresponds to the overall direction of movement of the product in the system. In operation, this direction is generally (but not limited to) the vertical direction, with the intake zone located above the distribution zone.

Throughout the present application, and in connection with the transfer wheel, an axial direction X is defined as a direction parallel to the axis of rotation X of the wheel.

A radial direction (for example Y) is also defined as a direction orthogonal to this axial direction.

A transverse plane is a plane normal to the axial direction.

The axis of rotation of the wheel is substantially orthogonal to the main direction, that is to say it is inclined by at most 30 degrees with respect to a plane normal to the main direction.

The wheel can be adapted to carry out, around its axis X, a rotational movement that is either continuous or alternating. In other words, the wheel is not necessarily adapted to make a full turn around its axis. In the case of an alternating movement, the amplitude of rotation is sufficient for the at least one pocket to be able to be filled with product in the admission zone and emptied in the dispensing zone.

The transfer wheel is provided at its periphery with at least one pocket, which can take very different shapes and dimensions.

By pocket is meant here any compartment forming a hollow with respect to the radial surface of the wheel and adapted to receive the product, in particular a powder.

Advantageously, the transfer wheel is provided at its periphery with a plurality of pockets regularly distributed over the radial surface of the wheel.

In what follows, the term “useful radial surface of the wheel” means the section of surface radially circumscribing the wheel and in which the pockets are made.

According to one example, the surface of the wheel cooperates by shape complementarity with the internal surface of the body. In particular, advantageously, the useful radial surface of the transfer wheel cooperates by form complementarity with a first radial interaction surface of the body on the side of its passage from the intake zone to the distribution zone and a second radial interaction surface of the body on the side of its passage from the distribution zone to the intake zone.

Advantageously, the curvilinear length, measured in a transverse plane, of each radial interface between the useful radial surface of the transfer wheel and a radial interaction surface of the body is at least equal to the maximum curvilinear length of the at least one pocket measured in a transverse plane.

When the wheel completes a full revolution around its axis, each pocket of the transfer wheel thus passes through an intermediate inlet sector where the pocket faces the first radial interaction surface and is completely covered by said surface, and by an intermediate outlet sector, where it faces the second radial interaction surface and is entirely covered by said surface.

The transfer system should be configured to prevent or substantially limit airflow between the body and the transfer wheel. For this, the transfer wheel and the body can for example cooperate by dimensional adjustment and/or by a system of seals.

According to one example, the play between at least one of the first and the second radial interaction surface and the useful radial surface of the transfer wheel can be made as small as possible, for example between 0.01 and 0.2 mm, preferably between 0.01 and 0.1 mm.

At the same time, the curvilinear length, measured in a transverse plane, of each radial interface between the useful radial surface of the transfer wheel and a radial interaction surface of the body is advantageously at least equal to 1/20 of the circumference of the wheel.

As an alternative or in addition, the wheel and the body can cooperate via at least one seal to achieve airtightness.

Preferably, at least one linear seal, preferably two linear seals, extending in the axial direction of the transfer wheel, is/are arranged on at least one of the first and the second radial interaction surface of the body or on the useful radial surface of the transfer wheel.

According to an advantageous arrangement, the at least two linear joints are, where appropriate, separated by a curvilinear distance - measured in a transverse plane - at least equal, preferably greater, to the maximum curvilinear length of a pocket of the wheel measured in a transverse plane. Such an arrangement ensures that each pocket always communicates with only one of the intake and distribution zones, including in a case where the body and the wheel are not dimensionally adjusted. Thus, two seals formed on a radial interaction surface of the body delimit between them and with the wheel a sealed dynamic airlock in which each pocket passes during rotation of the wheel. In the case of seals formed on the radial surface of the wheel, two seals located on either side of a pocket can cooperate with each radial interaction surface to form a sealed dynamic airlock.

To prevent the passage of air between the body and the side surfaces of the wheel, a circular seal may also be provided at each side end of said wheel. Circular seals can for example be arranged either on the outer radial surface of the wheel, on either side of the useful radial surface, or on the lateral end surfaces of the wheel.

A joint system can, if necessary, be perfectly airtight.

However, even if the flow of air between the body and the wheel is managed, in particular by means of one or the other solution described previously or a combination of these solutions, a certain quantity of air also passes through through the pockets carrying the product. In particular, even when a pocket is full of powder, it still contains at least a certain amount of air.

Particularly advantageously, to prevent this air from entering the treatment chamber, the transfer system may comprise an air extraction system for extracting the air contained in the at least one pocket before it arrives in the distribution area.

According to an exemplary implementation, this extraction system comprises at least one extraction conduit connected in a fluidic manner with a vacuum pump, and at least one filter to prevent the product from coming out of the pocket. The duct is adapted to communicate with each pocket to be emptied at least when this pocket is located on the intermediate inlet sector, where it faces the first radial interaction surface of the body, in other words during its passage from the zone admission to the distribution area.

Advantageously, the extraction duct can lead to said first radial interaction surface.

As an alternative, the extraction duct can also be formed in the transfer wheel, the filter forming at least part of the bottom of said at least one pocket.

• un bâti,
• une chambre de traitement délimitée par le bâti et susceptible d'être connectée en liaison fluidique avec une pompe à vide, la chambre de traitement étant munie d'une entrée pour l'introduction de produit à traiter et d'une sortie pour l'évacuation du produit traité,
• un système de transfert de produit tel que défini précédemment, agencé pour fermer l'entrée de la chambre de traitement, et
• des moyens de fermeture de ladite sortie.

According to a second aspect, the invention relates to a system for the vacuum treatment of a product, in particular a product in powder form, comprising:

• a frame,
• a treatment chamber delimited by the frame and capable of being connected in fluidic connection with a vacuum pump, the treatment chamber being provided with an inlet for the introduction of product to be treated and an outlet for evacuation of the treated product,
• a product transfer system as defined above, arranged to close the entrance to the treatment chamber, and
• means for closing said outlet.

According to one example, the processing chamber is a grinding chamber which includes a grinder.

According to one example, the processing system can comprise a second transfer system as defined previously, arranged to close the outlet of the processing chamber. In this case, the product intake zone is inside the treatment chamber and the distribution zone is a downstream zone where the product is recovered.

• la rotation de la roue de transfert pour l'amenée de produit en continu dans la chambre de traitement préalablement mise sous vide et,
• le traitement en continu du produit amené par la roue de transfert.

According to a third aspect, the invention also relates to a process for the vacuum treatment of a product by means of a treatment system as defined above, comprising at least one step a) during which are carried out simultaneously:

• the rotation of the transfer wheel for the continuous supply of product into the treatment chamber previously placed under vacuum and,
• the continuous treatment of the product fed by the transfer wheel.

According to one example, step a) further comprises extracting air from each pocket of the transfer wheel before it arrives in the distribution zone.

According to another example, step a) further comprises a suction of air contained in the treatment chamber during the treatment of the product.

According to another example, throughout step a), the absolute pressure differential between the inlet zone and the treatment chamber is maintained between 0.7 and 0.95 bar.

According to another example, during step a), the absolute pressure inside the treatment chamber is maintained between 0.05 and 0.3 bar (with the absolute pressure outside the treatment chamber and therefore in the area admission of the transfer system at the inlet of the chamber advantageously equal to atmospheric pressure).

• la zone d'admission peut être un réservoir de produit, par exemple sous la forme d'une trémie. Dans ce cas, la roue de transfert forme une paroi dudit réservoir de produit, et en particulier sa paroi de fond,
• le réservoir, la roue de transfert et la chambre de traitement peuvent être alignés verticalement, de sorte que la au moins une poche est remplie par gravité dans le réservoir et vidée par gravité dans la chambre de traitement,
• au moins l'un parmi la surface radiale de la roue de transfert et les surfaces d'interaction radiale peut être dans un matériau synthétique, notamment du PTFE,
• les poches peuvent être disposées en quinconce sur la surface radiale utile de la roue,
• la ou les poches peuvent être de forme hémisphérique,
• la ou les poches peuvent s'étendre en direction axiale, par exemple de façon continue sur au moins 50 pourcent de la longueur axiale de la roue de transfert.

Other more specific aspects of the present invention are further described below:

• the inlet zone can be a product reservoir, for example in the form of a hopper. In this case, the transfer wheel forms a wall of said product tank, and in particular its bottom wall,
• the tank, the transfer wheel and the treatment chamber can be aligned vertically, so that the at least one pocket is filled by gravity into the tank and emptied by gravity into the treatment chamber,
• at least one of the radial surface of the transfer wheel and the radial interaction surfaces may be made of a synthetic material, in particular PTFE,
• the pockets can be staggered on the useful radial surface of the wheel,
• the pocket(s) may be hemispherical in shape,
• the at least one pocket may extend axially, for example continuously over at least 50 percent of the axial length of the transfer wheel.

Brief description of the drawings

• La figure 1 est une vue d'ensemble, en perspective, d'un système de transfert selon un premier mode de réalisation de l'invention,
• La figure 2 est une vue partielle, en perspective, du système de transfert de la figure 1, selon un plan de coupe principal parallèle à l'axe de rotation de la roue de transfert,
• La figure 3 est une vue partielle, en perspective, du système de transfert de la figure 1, selon un plan de coupe principal orthogonal à l'axe de rotation de la roue de transfert,
• La figure 4 est une vue partielle du système de transfert de la figure 1, selon un plan de coupe principal parallèle à l'axe de rotation de la roue de transfert, et sur laquelle la roue de transfert a été omise pour montrer les joints d'étanchéité linéaires,
• La figure 5 montre une configuration possible d'un joint d'étanchéité radial à une extrémité latérale de la roue,
• La figure 6 montre le système d'évacuation d'air de la figure 3, en coupe selon le plan X-Y,
• La figure 7 est une vue partielle d'un système de transfert selon un deuxième mode de réalisation de l'invention, selon un plan de coupe principal parallèle à l'axe de rotation de la roue de transfert,
• La figure 8 est une vue partielle du système de transfert de la figure 7, selon un plan de coupe principal orthogonal à l'axe de rotation de la roue de transfert,
• La figure 9 est une vue schématique d'un système de traitement selon l'invention.

Other details of the invention will appear more clearly on reading the following description, made with reference to the appended drawings in which:

• There figure 1 is an overall view, in perspective, of a transfer system according to a first embodiment of the invention,
• There picture 2 is a partial view, in perspective, of the transfer system of the figure 1 , along a main section plane parallel to the axis of rotation of the transfer wheel,
• There picture 3 is a partial view, in perspective, of the transfer system of the figure 1 , along a main section plane orthogonal to the axis of rotation of the transfer wheel,
• There figure 4 is a partial view of the transfer system of the figure 1 , along a main section plane parallel to the axis of rotation of the transfer wheel, and on which the transfer wheel has been omitted to show the linear seals,
• There figure 5 shows a possible configuration of a radial seal at a side end of the wheel,
• There figure 6 shows the air exhaust system of the picture 3 , in section along the XY plane,
• There figure 7 is a partial view of a transfer system according to a second embodiment of the invention, along a main section plane parallel to the axis of rotation of the transfer wheel,
• There figure 8 is a partial view of the transfer system of the figure 7 , along a main section plane orthogonal to the axis of rotation of the transfer wheel,
• There figure 9 is a schematic view of a processing system according to the invention.

Embodiment of the invention

There figure 1 is an overview of a product transfer system 10 according to a first embodiment of the invention.

As seen on the figure 2 , this transfer system 10 comprises a body 12 delimiting a cavity 14 extending in a main direction Z.

At its upper end 121, the body 12 forms a reservoir in the form of an inlet hopper 16 which can be filled with product. At its lower end 122, the body 12 has an opening 18 for the exit of the product, by which it can be fixed, for example to a frame of a processing system as will be described below with reference to the figure 9 .

A transfer wheel 20 (hereafter wheel) is housed in the cavity 14.

Inside the cavity 14, in the main direction Z, the wheel 20 forms a separation between a product intake zone A and a product distribution zone D.

The product intake zone A is here the tank 16 formed by the hopper and the bottom of which is formed by the radial surface 21 of the wheel 20.

The distribution zone D can be, in use, the interior of a product treatment chamber.

The transfer wheel 20 is here secured to a shaft 24 adapted to rotate around its axis X under the action of a drive motor 25 visible on the figure 1 , thanks to a set of bearings 26, 27.

The transfer wheel 20 here has the shape of a right cylinder, as is apparent in particular from the picture 3 .

It is thus delimited radially by a radial surface 21, and axially by a first lateral end surface 22 and a second lateral end surface 23 (hereinafter end surfaces 22, 23) substantially planar, orthogonal to the axis of rotation X.

According to alternative embodiments, the transfer wheel could however have a different shape, in particular a spherical or ovoid shape. In such cases, the radial surface of the wheel could correspond to the entire surface of the wheel 20.

As illustrated on the figure 2 And 3 in particular, the wheel 20 comprises, on a part of its radial surface 21 called the useful radial surface 211, a plurality of recessed pockets or compartments 28. These pockets 28 are intended to fill with product in the admission zone A and to empty themselves of their contents in the distribution zone D.

In order to ensure a regular and substantially homogeneous distribution of product in the distribution zone D, the pockets 28 are advantageously distributed regularly over the whole of the useful radial surface 211 of the wheel 20.

In the particular example considered, each pocket 28 has a hemispherical shape, and the pockets are staggered.

The wheel 20 cooperates by form complementarity with the internal surface 13 of the body 12.

In particular, the useful radial surface 211 of the wheel, carrying the pockets 28, cooperates by form complementarity with a first radial interaction surface 131 of the body 12 on the side of its passage from the intake zone A to the zone of distribution D and with a second radial interaction surface 132 on the side of its passage from the distribution zone D to the intake zone A (see direction of rotation f on the picture 3 ).

By cooperating by complementarity of shape, it is meant in the present application that the elements concerned have corresponding shapes. On either side of the wheel 20, in the radial direction Y orthogonal to X and Z, the body 12 thus matches the curvature of the wheel 20 so that the radial gap between the body and the useful radial surface 211 has a substantially constant width in the Y direction over its entire length in the Z direction.

In a transverse plane of the distribution wheel, the curvilinear length C131, respectively C132 of the radial interface between the transfer wheel 20 and each radial interaction surface 131, 132 is strictly less than half the circumference of the wheel 20.

At the same time, the curvilinear length C131, C132 of the radial interface between the transfer wheel 20 and each radial interaction surface 131, 132, measured in a transverse plane, is at least equal to the maximum curvilinear length C28 of each pocket 28 measured in a transverse plane. In this way, when the wheel 20 completes a complete turn around its axis X, each pocket 28 of the wheel 20 passes through an admission sector SA where it faces the admission zone A, an intermediate sector of entrance SE where it faces the first radial interaction surface 131 of the body 12 and is completely covered by said surface 131, a distribution sector SD where it faces the distribution zone D and an intermediate output sector SS, where it faces the second radial interaction surface 132 and is entirely covered by said surface 132 (see picture 3 ).

In the particular example illustrated and as seen in the picture 2 , each end surface 22, 23 of the wheel 20 also cooperates by shape complementarity with an axial interaction surface respectively 133, 134 of the body.

In the system according to the invention, the body 12 and the wheel 20 cooperate to form between the intake zone A and the distribution zone D a substantially airtight barrier.

This seal, which must be ensured when stationary and when wheel 20 rotates, is achieved at two levels:
On the one hand, the air is prevented from circulating at the interface between the wheel 20 and the body 12.

In the embodiment of the figure 1 , the body 12 and the wheel 20 are dimensionally adjusted for this.

The play between each radial interaction surface 131, 132 of the body 12 and the useful radial surface 211 of the transfer wheel 20 is minimized, and preferably between 0.01 and 0.2 mm, preferably between 0.01 and 0.1 mm.

The same is preferably true of the play between each end surface 22, 23 of the wheel 20 and the axial interaction surface 133, 134 of the body 12 facing it.

Also, the curvilinear length C131, C132 of the interface between the transfer wheel 20 and each radial interaction surface 131, 132 is preferably equal to at least 1/20
of the circumference of the wheel 20.

The interface between each interaction surface 131, 132, 133, 134 of the body and the useful radial surface 211 of the wheel 20 is thus sufficiently narrow and long for the pressure gradient at the level of the interface to be the highest. possible. In this way, the pressure drops at the interface are then sufficient to prevent the passage of air.

The curvilinear length of the interface also being greater than that of a pocket 28 as indicated above, preferably equal to at least twice the maximum curvilinear length of the pocket 28 measured in a transverse plane, the wheel 20 and the body 12 are arranged so that each pocket 28 only communicates simultaneously with one or the other of the admission zone A and the distribution zone D.

With such an adjustment of the parts, in order to avoid pollution of the product by wear particles resulting from the friction between the transfer wheel and the body, it is advantageous that at least one of the wheel 20 and the surfaces of interaction 131, 132, 133, 134 is (in) t in a synthetic material, in particular polytetrafluoroethylene (PTFE).

The body can for example be made of ceramic or metal, and the impeller 20 of PTFE.

Advantageously, as in the example of figures 1 to 4 , the precise adjustment of the wheel 20 and the body 12 is further reinforced by the presence of seals at the interface between the two parts.

As illustrated on the figure 3 And 4 , each radial interaction surface 131, 132 here carries two linear seals 411, 412, respectively 421, 422, extending in the axial direction X over a length at least equal to the axial length of the useful radial surface 211 of the wheel 20 and configured to cooperate with said useful radial surface 211. These seals are advantageously scraper seals. The two seals 411, 421, respectively 421, 422 of the same pair are separated by a curvilinear distance C41 respectively C42 - measured in a transverse plane - at least equal, preferably greater, to the curvilinear length C28 of a pocket 28 of the wheel 20 measured in a transverse plane. Such an arrangement ensures that each pocket 28 always communicates with only one of the intake A and distribution D zones, including in a case where the body 12 and the wheel 20 are not dimensionally adjusted.

According to an alternative arrangement, a plurality of linear seals could also be provided on the radial surface 21 of the transfer wheel 20, regularly distributed over its circumference, and configured to cooperate with the radial interaction surfaces 131, 132 of the body to achieve sealing.

A circular seal 431, 432 (forming a closed contour in a transverse plane of the wheel, see figure 5 And figure 7 ), can also be provided at each side end 201, 202 of the wheel 20.

As illustrated on the figure 5 , the lateral ends 201, 202 of the wheel 20 can be inserted over a short axial length, in a corresponding part of the body 12. In other words, at each lateral end 201, 202 of the wheel 20, the outer radial surface 212 of the wheel 20 cooperates by shape complementarity with a cylindrical internal surface 135, 136 of the body 12. A radial seal 431, 432 mounted at the periphery of the wheel 20 can thus cooperate radially with said cylindrical internal surface 135, 136 facing .

There figure 5 illustrates the arrangement of a circular joint 431 at the side end 201 of the wheel. The circular seal 431 is here a lip seal, with a substantially L-shaped section. It could however be an O-ring or any other suitable type of seal. According to the arrangement illustrated, a first planar annular part 4311 of the joint is fixed to the lateral end surface 22 of the wheel 20 by means of a washer 441 applied against said first part 4311 on the one hand and against said surface of end 22 on the other hand and fixed to said surface by screws 451. A second cylindrical part 4312 of the seal, extending said first part, forms a lip projecting with respect to the useful radial surface 211 of the wheel and adapted to come apply by deforming against the inner surface 135 of the body. The elasticity of the lip presses it against the surface of the body, thus ensuring the seal.

As a variant, a circular seal could be provided on each side end surface 22, 23 of wheel 20, to cooperate with a surface 133, 134 of body 12 located opposite.

In the first embodiment described above, the seal between the surface of the wheel 20 and the body 12 is achieved by a dimensional adjustment of the parts and by a set of seals. According to an alternative embodiment, sealing could also be achieved solely by a dimensional adjustment of the parts, or solely by a set of seals, or by a combination different from that described in connection with the first embodiment (for example: the dimensional adjustment could be omitted between the lateral end surfaces of the wheel 20 and the facing body 12).

Even if the flow of air between the body 12 and the wheel 20 is managed, in particular by dimensional adjustment of the two parts or by a system of seals or a combination of these solutions, a certain quantity of air transits also through the pockets 28 carrying the product. In particular, even when a pocket 28 is full of powder, it still contains at least a certain amount of air.

In a particularly advantageous manner, to prevent this air from entering the distribution zone (which is generally a vacuum treatment chamber), the transfer system 10 comprises an air extraction system 50 for extracting the air contained in the at least one pocket 28 before its arrival in the distribution area D.

In the example illustrated, as seen in particular on the picture 3 , the extraction system 50 is integrated into the body 12: it comprises an extraction duct 51 opening into the cavity 14 and fluidically connected with a vacuum pump, not shown, and a filter 52 to prevent the product from coming out of the pocket, forming part of the first radial interaction surface 131.

The conduit 51 is adapted to communicate with each pocket 28 to be emptied when this pocket is located on the intermediate inlet sector SE, where it faces the first radial interaction surface 131, in other words during its passage from the zone intake A to distribution area D.

In order to be able to evacuate all of the pockets 28 of the wheel 20 during the rotation of the latter, the conduit 51 comprises at least one section of length - measured in the axial direction X—substantially equal to the axial length of the useful radial surface 211 over which the pockets 28 of the wheel 20 extend. figure 6 , the conduit 51 comprises such a section 511 terminated by the filter 52 and extended by a second section of reduced diameter allowing connection to the vacuum pump.

When a pocket 28 arrives opposite the duct 51, on the entry sector SE, it no longer communicates with the admission zone A, and does not yet communicate with the distribution zone D. Let the clearance between the body and the wheel prevents the passage of air between zones A and D and pocket 28, or axial seals 411, 412 are arranged on either side of pocket 28 and on either side of the duct 51 so as to form a sealed intermediate airlock between the two zones A and D, or both.

The air contained in pocket 28 is then sucked up under the action of the vacuum pump. The product is itself stopped by the filter 52 and thus remains inside the pocket 28.

As an alternative or in addition, an extraction duct could also be integrated into the transfer wheel 20, the filter forming at least part of the bottom of each pocket 28.

THE figure 7 And 8 illustrate a transfer system according to a second embodiment of the invention, similar to that described in connection with the figures 1 to 6 but in which the pockets are of different shapes. All the numerical references relating to elements identical or similar to the elements described above are numbered with the same references in these figures and are not described again.

In this example, as seen in the figure 7 , each pocket 29 is in the form of an elongated groove, extending in the axial direction X of the wheel 20. More specifically, each pocket extends in the axial direction over a length L2 equal to at least 50% of the axial length L1 of the wheel 20.

In cross-section, as shown in the figure 8 , the pockets have, for example, an outwardly flared profile, substantially V-shaped.

There figure 9 schematically illustrates a processing system 100 comprising a processing chamber 90 and at least one transfer system 10 according to the invention to supply this chamber 90.

The treatment chamber 90 is delimited by a frame 93. It comprises an inlet 91 for the introduction of the product P to be treated, and an outlet 92 for the evacuation of the treated product.

In this case, the inlet 91 of the treatment chamber 90 is located close to the upper end of this chamber 90 and the outlet 92, close to its lower end.

The inlet 91 of the treatment chamber is closed by the first transfer system 10a according to the invention, the wheel of which acts as a metering device.

According to an advantageous arrangement, the outlet 92 of the chamber 90 is closed by a second transfer system 10b according to the invention. Alternatively, the outlet 92 of the chamber 90 could also be closed by a sealed valve or by an airlock closed by two valves, the evacuation of the product not necessarily being carried out continuously.

The processing chamber 90 houses at least one device 94 for processing the product. The product to be treated is for example a powder, formed of grains of maximum diameter comprised for example between 100 and 1000 microns.

According to an example of use, the chamber 90 is for example a grinding chamber and this processing device 94 is a grinder. In the case of a powder of the aforementioned type, the grinder 94 is for example suitable for obtaining, after treatment, a maximum diameter of the grains comprised for example between 10 and 100 microns.

In the particular example illustrated, the product distributed in the treatment chamber 90 by the first transfer system 10a falls by gravity into the treatment device 94 located below, then towards the outlet 92.

The interior of the treatment chamber 90 communicates with a vacuum pump 97 via a conduit 95 leading to an opening 96 of the chamber 90. To prevent the aspiration of product when the pump 97 is in operation, the opening 96 can be protected by a 99 filter system.

In the processing system previously described in connection with the figure 9 , the treatment chamber 90 is preferably placed under vacuum, at an absolute pressure of between 0.05 and 0.3 bar during the product treatment operation. This vacuum makes it possible to avoid the deterioration of the product by oxidation and to limit the risks of explosion in the event of a flammable product.

The tank 16 - which forms the product intake zone A for the first system 10a is itself open to the outside, and therefore typically at atmospheric pressure.

The system 10a closes the inlet 91 of the treatment chamber so as to allow it to be evacuated and to maintain this vacuum, while allowing the continuous distribution of product P inside the chamber 90.

In the same way, the second transfer system 10b makes it possible to evacuate the treated product to a downstream receiving device 98 while ensuring sufficient airtightness for the vacuum and the vacuum maintenance of the chamber 90.

The use of such a processing system is as follows:
The processing chamber is evacuated using the vacuum pump 97.

Reservoir 16 is filled with product to be treated.

The transfer wheel 20 of the first transfer system is set in rotation using the drive motor 25. By gravity, the pockets 28 of the wheel 20 are filled with product P. Advantageously, the extraction system air 50 is activated to create a vacuum inside each bag before it arrives in the treatment chamber.

At the same time, the processing device is actuated to be able to immediately and continuously process the product P dispensed by the wheel 20.

If necessary, the transfer wheel of the second system 10b is simultaneously set in rotation to continuously evacuate the treated product to a downstream receiving device 98.

If the distribution systems 10a and 10b are perfectly sealed, for example thanks to the implementation of a set of seals as described previously, the chamber remains under vacuum throughout the duration of the treatment, in particular thanks to the extraction systems air 50 which carry out an intermediate vacuum of each pocket between the reservoir 16 and the treatment chamber 90, respectively between the treatment chamber 90 and the outside of the chamber.

If one or the other of the distribution systems 10a, 10b allows a certain quantity of air to pass between the body and the wheel and/or through the pockets, then the method includes compensating for this air ingress by activating the vacuum pump 97 during the processing operation.

Claims (19)

System (10) for transferring product (P), said transfer system (10) comprising: - a body (12) delimiting a cavity (14) extending in a main direction (Z), and - a transfer wheel (20) housed at least partially in said cavity (14) and separating in said main direction (Z) a product intake zone (A) and a product distribution zone (D), the wheel transfer (20) being provided with at least one pocket (28, 29) at its periphery and being adapted to rotate around an axis (X) substantially orthogonal to said main direction (Z) so that said pocket (28 , 29) brings product from said intake zone (A) to said distribution zone (D),
the transfer system (10) being characterized in that the transfer wheel (20) and the body (12) cooperate to form a substantially airtight barrier between the intake zone (A) and the distribution zone (D). A transfer system (10) according to claim 1, wherein the transfer wheel (20) and the body (12) cooperate by dimensional adjustment and/or by a joint system to form said substantially airtight barrier. Transfer system (10) according to claim 1 or 2, comprising an air extraction system (50) for extracting the air contained in the at least one pocket (28, 29) before its arrival in the distribution zone (D). Transfer system (10) according to claim 3, wherein the extraction system (50) comprises at least one extraction conduit (51) fluidically connected with a vacuum pump, and at least one filter (52) to prevent the product from coming out of the pocket (28, 29). A transfer system (10) according to claim 4, wherein the extraction duct (51) is formed in the transfer wheel (20), and the filter (52) forms at least part of the bottom of said at least one pocket (28, 29). Transfer system (10) according to any one of claims 1 to 5, in which a working radial surface (211) of the transfer wheel (20) cooperates by form complementarity with a first radial interaction surface (131) of the body (12) on the side of its passage from the intake zone (A) to the distribution zone (D) and a second radial interaction surface (132) of the body (12) on the side of its passage from the distribution zone (D) to the admission zone (A). Transfer system (10) according to claim 6, in which the curvilinear length (C131, C132), measured in a transverse plane, of each radial interface between the effective radial surface (211) of the transfer wheel (20) and a radial interaction surface (131, 132) is at least equal to the maximum curvilinear length (C28) of the at least one pocket (28) measured in a transverse plane. Transfer system (10) according to claim 6 or 7, in which the clearance between at least one of the first and the second radial interaction surface (131, 132) of the body (12) and the effective radial surface ( 211) of the transfer wheel (20) is between 0.01 and 0.2mm, preferably between 0.01 and 0.1mm. Transfer system (10) according to any one of claims 6 to 8, in which the curvilinear length (C131, C132), measured in a transverse plane, of each radial interface between the working radial surface (211) of the transfer (20) and a radial interaction surface (131, 132) of the body (12) is at least equal to 1/20 of the circumference of the wheel (20). Transfer system (10) according to Claim 4 or 5 and any one of Claims 6 to 9, in which the extraction duct (51) opens onto the said first radial interaction surface (131) of the body (12). . Transfer system (10) according to any one of claims 1 to 10, in which at least one linear seal (411, 412, 421, 422), preferably at least two linear seals, extending in the axial direction (X) of the transfer wheel (20), is arranged on at least one of the first and the second radial interaction surface (131, 132) or on the radial working surface (211) transfer wheel (20). Transfer system (10) according to any one of Claims 1 to 11, in which the transfer wheel (20) is provided with a plurality of pockets (28) arranged in staggered rows and regularly distributed over its entire circumference. Vacuum treatment system (100) for a product (P), in particular a product in powder form, comprising: - a frame (93), - a treatment chamber (90) delimited by the frame (93) and capable of being connected in fluidic connection with a vacuum pump (97), the treatment chamber (90) being provided with an inlet (91) for the introduction of product to be treated (P) and an outlet (92) for the evacuation of the treated product, - a product transfer system (10) according to any one of claims 1 to 12, arranged to close the inlet (91) of the treatment chamber (90), and - Means for closing said outlet (92). A processing system (100) according to claim 13, wherein the processing chamber (90) is a grinding chamber which includes a grinder. A processing system (100) according to claim 13 or 14, comprising a second transfer system (10b) according to any one of claims 1 to 11 arranged to close the outlet (92) of the processing chamber (90). Process for the vacuum treatment of a product (P) by means of a treatment system (100) according to any one of Claims 13 to 15, comprising at least one step a) during which are carried out simultaneously: - the rotation of the transfer wheel (20) for the supply of product (P) continuously into the treatment chamber (90) previously placed under vacuum and, - the continuous treatment of the product (P) supplied by the transfer wheel (20). A method of treatment according to claim 16, wherein step a) further comprises extracting air from each pocket (28, 29) of the transfer wheel (20) prior to its arrival in the distribution zone (D ). A method of treatment according to claim 16 or 17, wherein step a) further comprises aspirating air contained in the treatment chamber (90) during the treatment of the product. Treatment method according to any one of Claims 16 to 18, in which, throughout step a), the absolute pressure differential between the inlet zone (A) and the treatment chamber (90) is maintained between 0.7 and 0.95 bar.

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