TECHNICAL FIELD

The present invention refers to pressing grapes and in particular to pressing more or less high quality grapes for obtaining quality wines.

BACKGROUND ART

In the wine production process pressing grapes is one of the most difficult and sensitive activities.

Actually during the pressing there occurs the breakage of the skin of the grapes, hence releasing the content of the grapes in form of must.

During this operation, in case of high quality grapes, one must be particularly careful to avoid mechanically mishandling the product, which could lead to unwanted lees deriving from the partial destruction of the skins, or even from the breakage of the seeds and grape-stalks, hence releasing unwanted substances.

The prior art provides for various types of presses for obtaining the wine must.

There are known mechanical presses the most common of which comprise an auger operating within a perforated cylinder, adapted to mechanically push the mass of grapes towards one end of the cylinder, continuously pressing it.

Mechanical pressing does not guarantee a soft pressing sufficient to guarantee the quality of the must, in that the grapes are subjected to unwanted mishandling, deriving from the contact with mobile mechanical parts.

These presses operate continuously and have a good production capacity, but they reveal poor capacity to adapt the pressing parameters, especially the pressing pressure, to the variable conditions of the product to be processed.

Also known are the so-called membrane presses, where grape pressing is performed by a deformable membrane which divides a container into two parts, one of which is occupied by the fluid being pressed which is designated to deform the membrane, and the other, provided with a perforated wall, is occupied by the product to be pressed.

Membrane presses have characteristics that guarantee the desired pressing sensitiveness, but they reveal the considerable disadvantage of operating only in discontinuous mode.

The types of mechanical press are not suitable for processing whole grapes complete with grape-stalks, and require - before intervention thereof - that the grapes be pressed and possibly the stalks removed so as to avoid the extraction of substances from the stalk that jeopardize the quality of the must. The object of the present patent is to provide and protect a pressing system that overcomes the drawbacks of the known systems which allow pressing the grapes continuously, but with the sensitivity required to preserve the characteristics of the product.

A further object of the patent is to provide a pressing system capable of processing not only de-stemmed grapes, but also whole grapes, through an action that can be easily controlled from outside to maintain the pressing parameters, especially the pressure, at the desired values.

DISCLOSURE OF THE INVENTION

The aforementioned objects of the invention are attained by the system having the characteristics outlined in claim 1 and by the process whose characteristics are outlined in claim 9.

The dependent claims refer to the subordinate claims adapted to improve the performance of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages as well as the construction and functional characteristics of the invention will be apparent from the detailed description that follows, which illustrates a particular preferred embodiment thereof provided by way of non- limiting example with reference to the attached drawings.

Fig 1 shows the side view of the invention with the upper part sectioned on the axis;

Fig 2 shows Fig 1 in plan view; Fig 3 shows the section Ill-Ill of Fig 1 ;

Fig 4 shows Fig 1 in a different operating position;

Fig 5 shows the section V-V of Fig 4.

BEST MODE FOR CARRYING OUT THE INVENTION

The figures illustrate a press comprising a cylindrical container 1 having the perforated lateral wall 2, reinforced by stiffening ribs 3.

The container 1 may have a first frusto-conical part 110 which is connected with a second cylindrical part 120, arranged downstream in the direction of the flow.

Alternatively the container may be cylindrical with constant section over the entire length thereof.

The container is supported stationary on a framework 4, made of metal trestle, which - in the part beneath the container - 1 receives a removable vat 5 provided with wheels 51.

The container 1 is supported, through the ribs 3, by two lateral currents 6 (Fig

2) arranged on the horizontal diametric plane of the container, in turn connected to the framework 4 through means (not illustrated) adapted to place the container both with the horizontal axis and with the inclined axis with respect to the conical part arranged further below.

At one end of the container 1 the currents 6 are connected to a crosspiece 61 integral with the bottom wall 11 of the container, to which there is connected a connection 12 coming from a pump (not illustrated).

The pump is a variable displacement pump and it is connected to the central control system.

At the opposite end of the container 1 the currents 6 carry a crosspiece 62 (Fig 2) fixed thereto which in turn supports an actuator 8 at the centre.

The actuator 8 is hydraulic or mechanical, for actuating the stem of a piston 9, and it is connected to the central control system.

The head of the piston comprises, should the actuator be electrical, a thrust sensor (not illustrated) like a loading cell.

The piston 9 comprises a cylindrical portion 90 provided with two sealing bearings 91 adapted to be fittingly and sealingly inserted into the cylindrical container 1 , as well as a conical part 92 having the vertex facing towards the bottom wall 11 of the container.

The conical part has the task of improving the shape of the discharge opening for the pressed product, and it may also be shaped differently to suit the purpose.

Four radial guide fins 93 whose edge parallel to the axis is in line with the cylindrical portion 90 and whose front part is sharp-edged are derived from the conical part. The fins have the purpose of cutting and breaking the pressed material.

The travel of the piston 9 within the container extends not exceeding the cylindrical portion 120 thereof.

When the piston 9 is arranged facing the end of the container downstream in the direction of flow, with the cylindrical portion thereof close to but outside with respect thereto, it creates an adjustable opening from which the pressed product is discharged. The position of the piston is controlled by the central control system.

In this position the piston may be subjected to a reciprocating movement, with brief travel, to improve the cutting and breaking operation of the fins. Beneath the crosspiece 62 and the actuator 8 there is arranged a vat 50 for collecting the pressed product which exits from the adjustable opening, which is referred to as rape.

The perforated lateral wall 2 of the container 1 comprises a semi-cylindrical upper portion 21 (Figs 4, 5), each of whose edges carry a portion 22 hinged thereto with a curved section shaped like a quarter of a cylindrical surface, each portion being associated to means (not illustrated) which place it in a closed position continuing the other portion and the upper portion, or in a substantially vertical open position (Fig 5).

A central control system, per se known, regulates the capacity of the pump and the position of the piston as a function of the various monitored parameters which are represented by the pressure with which the pump supplies the cylinder, by the amount of the capacity of the pump, by the thrust exerted by the material being discharged on the head of the piston and by the position of the piston.

The invention operates as follows.

At the beginning of the pressing the piston 9 is inserted into container up to the end upstream of the cylindrical portion 120 thereof, and the portions 22 are in closed position.

A pump, not illustrated, of the type operating at low regime at a speed controlled by the central control system, sends the product into the container 1 through the connection 12 located in the bottom wall 6 thereof.

The connection can be conveniently provided with a unidirectional valve (not illustrated) adapted to prevent the back flow of the product towards the pump. The product may be constituted by whole or de-stemmed grapes and it also comprises a liquid phase constituted by juice.

Once the solid phase of the product fills the portion of the cylindrical container limited by the piston 9, while the present liquid phase drains through the perforated wall of the container, by continuing pumping there occurs a gradual increase of the pressure until the desired pressing value is reached.

Upon reaching this value, read by the sensor, the piston is controlled by the central control system to recede increasing the volume available within the container, until it is arranged immediately outside the container to create the opening for discharging the pressed material.

The position of the piston is calibrated by the central control system in a manner such to keep the desired internal pressure value constant.

By continuing the pumping, the pressed material exits from the calibrated opening at the end of the container, and the pressing and the advancement of the material occur continuously, at the desired pressure, in absence of mechanical actions, and only due to the pressurized supply of the material. During this step the juice or must drains through the perforated wall falling into the underlying vat 5, and the pressed material exits from the opening created by the piston and falls into the underlying vat 50. The vat 5 may comprise several separated sections in the direction of advancement of the material.

In the mass of pressed material the amount of liquid reduces constantly towards the end downstream of the container.

Also the quality of the must reduces as the must content reduces in the material given that the best must is the one pressed in the section most downstream of the container.

It is thus advantageous to receive the must selectively, keep the quality of degrading must low towards the exit of the container.

The size of the calibrated discharge opening is determined by the position of the piston, which is in turn determined by the central control system.

At the end of the pressing the press is cleaned as follows.

The vat 5 full of must is removed and it is replaced with an empty vat.

Then the portions 22 of the perforated wall, with which the solid part of the product falls into the underlying vat, are arranged in open position.

In order to facilitate the complete emptying of the container, the piston is made to advance therewithin up to the end of the cylindrical portion thereof.

Final washing may complete the operation.

It is understood that the invention is not restricted to the previously described example and it may be subjected to variants and improvements without departing from the scope of protection of the following claims.

Actually, the invention is suitable to produce juice from vegetables different from grapes and the means for discharging the juice or the used material may be mechanised.