Patent Description:
In the state of the art, machines for dispensing infusion beverages are equipped with complex systems to regulate the pressure of the infusion fluid.

In particular, most coffee makers are equipped with a dynamic brewing pressure regulation system that consists of three elements, namely, a proportional valve, a control board, and a pressure transducer.

The proportional valve allows the pressure of the infusion fluid to be varied in such a way that an input variation at the valve is directly proportional to the output variation. In other words, the ratio of inlet pressure to outlet pressure is kept constant.

The control board is equipped with a CPU unit integrated on the board itself and enables a closed-loop control over the hydraulic circuit of the infusion fluid.

Finally, the pressure transducer detects the pressure value of the infusion fluid.

The operation of the dynamic brewing pressure regulation system provides for a pump feeding the proportional valve with the infusion fluid. Downstream of the valve, the transducer that detects the pressure value and sends this value to the control board is placed. The control board, depending on the value received from the transducer, changes the pressure of the infusion fluid entering the proportional valve.

The combination of the three elements (valve, transducer, and control board) makes it possible to vary the dispensing pressure quickly and accurately.

Disadvantageously, the dynamic pressure regulation system is expensive, as it requires feedback control.

An additional disadvantage stems from the fact that the system is bulky, because in addition to the valve, the transducer and the control board are also necessary; moreover, the control board also deals with high and low voltage management.

A machine for dispensing an infusion beverage according to the preamble of claim <NUM> is known from <CIT>.

The object of the present invention is to propose a machine for dispensing an infusion beverage that is able to at least partially solve the drawbacks described above. In particular, it is the object of the present invention to obtain a system for controlling the dispensing pressure that is economical and compact.

Said object is achieved with a machine for dispensing an infusion beverage according to claim <NUM>. The dependent claims describe preferred embodiments of the invention.

The features and the advantages of the machine for dispensing an infusion beverage according to the invention shall be made readily apparent from the following description of preferred examples of embodiments thereof, provided purely by way of a nonlimiting example, with reference to the accompanying figures, wherein:.

In the following description, elements common to the various embodiments represented in the drawings are indicated with the same reference numerals.

In said drawings, <NUM> is used to denote a machine for dispensing an infusion beverage according to the invention as a whole.

In a general embodiment, the machine <NUM> is suitable for dispensing an infusion beverage, such as coffee, chamomile tea, tea, or herbal tea. Said machine <NUM> comprises a pump group <NUM>, a dispensing group <NUM> and a flow adjustment solenoid valve <NUM>.

For example, the pump group <NUM> is a rotary pump, commonly used in coffee machines, and is suitable for pumping an infusion fluid. For example, the infusion fluid is water, or milk, an alcoholic beverage, or a combination thereof.

The dispensing group <NUM> is arranged downstream of the pump group <NUM> and is fluidly connected thereto. Moreover, the dispensing group <NUM> comprises a filtration member suitable for containing an organic substance wettable by the infusion fluid so as to obtain the corresponding infusion beverage to be dispensed. In particular, the filtration member is a filter holder that comprises within it a filter where the coffee is added.

The flow adjustment solenoid valve <NUM> extends along a valve axis V and is fluidly interposed between the pump group <NUM> and the dispensing group <NUM> so as to control the flow rate of the infusion fluid.

Preferably, the flow adjustment solenoid valve <NUM> adjusts the pressure and/or speed of the infusion fluid to function as a flow regulator.

The flow adjustment solenoid valve <NUM> further comprises a shutter <NUM> movable along the valve axis V.

Said solenoid valve is configurable in a closing configuration, in which the pump group <NUM> is inactive and the shutter <NUM> occludes the passage of the infusion fluid from the pump group <NUM> to the dispensing group <NUM>, and in a complete opening configuration, in which the pump group is operational and the shutter <NUM> is fully raised so that the infusion fluid may reach the dispensing group.

According to the present invention, the flow adjustment solenoid valve <NUM> comprises flow adjustment means <NUM> suitable for regulating the passage of the infusion fluid.

According to one aspect of the invention, between the closing configuration and the complete opening configuration, the flow adjustment solenoid valve <NUM> is arranged in an intermediate opening configuration, where the pump group <NUM> is operational and the flow adjustment means <NUM> allow partial lifting of the shutter <NUM> so as to partialize the flow rate of the infusion fluid from the pump group to the dispensing group.

Preferably, the flow adjustment means <NUM> are fully integrated into the flow adjustment solenoid valve <NUM>.

Advantageously, the regulation of the infusion fluid flow rate is only possible by the flow adjustment solenoid valve that regulate the pressure and/or the speed of the infusion fluid. Therefore, the machine is compact, as no additional elements, such as the pressure transducer or the control board, are needed.

Preferably, the flow adjustment means <NUM> are either fully mechanical or are electronically controlled mechanical means, such as controlled by a computer program. In other words, the flow adjustment means <NUM> are not fully electronic and are not configured as a closing-loop control.

When the flow adjustment solenoid valve <NUM> is in the intermediate opening configuration, the machine <NUM> operates under "low flow" conditions, that is, with low infusion fluid flow rate values. For example, in the intermediate opening configuration, the infusion fluid pressure is in the range of <NUM> to <NUM> bar. The intermediate opening configuration is extremely useful during the steps of "blooming," pre-infusion and at the end of dispensing. It is well known to the person skilled in the art that the step of "blooming" or "flowering" is the step in which the organic substance in the filtration member is initially wetted by the infusion fluid. The pre-infusion stage precedes beverage dispensing and is the stage in which the infusion fluid fills the filtration member by wetting the organic matter completely. Finally, during the end stage of brewing, the final extraction from the organic matter occurs, so that the beverage is lengthened.

On the other hand, when the flow adjustment solenoid valve <NUM> is in the complete opening configuration, the machine <NUM> operates under "full flow" conditions, i.e., with high flow rate values of the infusion fluid. For example, in the complete opening configuration, the pressure of the infusion fluid is between <NUM> to <NUM> bar. It is known to the person skilled in the art that the stage of dispensing the infusion beverage through dispensing group <NUM> occurs under "full flow" conditions, i.e., when the flow adjustment solenoid valve <NUM> is in a complete opening configuration.

In one embodiment, the flow adjustment solenoid valve comprises a valve body <NUM> delimiting an inlet chamber <NUM>, a flow adjustment chamber <NUM>, and an outlet chamber <NUM>.

The inlet chamber <NUM> is connectable to the pump group <NUM>; in the flow adjustment chamber <NUM> the shutter <NUM> is translatable, and the outlet chamber <NUM> is connectable to dispensing group <NUM>.

Said inlet <NUM>, flow adjustment <NUM>, and outlet <NUM> chambers are arranged in succession and fluidly connected to each other.

According to one embodiment, the flow adjustment solenoid valve <NUM> also comprises a tubular element <NUM>, a first core <NUM>, and a piston <NUM>.

The tubular element <NUM> is engaged to the valve body <NUM>, and the first core <NUM> is operatively connected to the tubular element <NUM>.

Preferably, the first core <NUM> is integral to the tubular element <NUM>, e.g., it is connected by welding.

The piston <NUM> comprises the shutter <NUM> and extends between a head end <NUM>' and a tail end <NUM>". Said piston <NUM> is at least partially housed inside the tubular element <NUM>, so that it is guided by the tubular element in the translation between the closing configuration and the complete opening configuration.

Preferably, the valve body <NUM>, the tubular element <NUM>, and the first core <NUM> delimit a piston translation chamber <NUM> where the piston <NUM> is at least partially slidingly housed. Said piston translation chamber <NUM> faces the flow adjustment chamber <NUM> and is fluidly connected thereto.

In one embodiment, the piston <NUM> also comprises a second core <NUM>, a thrust pad <NUM>, a spacer <NUM> and a second elastic element <NUM>.

The second core <NUM> internally has a hole <NUM> that forms, at the head end <NUM>', a shutter chamber <NUM> where the shutter is at least partially housed.

The thrust pad <NUM> is in contact with the shutter <NUM>, whereas the spacer <NUM> is placed in a seat <NUM> obtained in the hole <NUM>.

The second elastic element <NUM> is precompressed and is interposed between the thrust pad <NUM> and the spacer <NUM> so as to elastically connect them together, keep the thrust pad <NUM> abutting against the shutter <NUM>, and keep the spacer <NUM> in its respective seat <NUM>.

Said thrust pad <NUM>, second elastic element <NUM> and spacer <NUM> are housed in axial succession, i.e., along the valve axis V, within the hole <NUM>.

According to one embodiment, the valve body <NUM> comprises an annular wall <NUM>' that delimits the flow adjustment chamber <NUM>.

Moreover, the tubular element <NUM> comprises an annular portion <NUM> that is engaged to the annular wall <NUM>' with shape and/or interference coupling, for example by threaded connection. This annular portion <NUM> is delimited axially by an abutting undercut <NUM> that forms a step.

A flange <NUM> is obtained at the head end <NUM>', which protrudes radially outward.

Flow adjustment means <NUM> comprise a first elastic element <NUM> fitted externally on the piston <NUM>, preferably at the head end <NUM>'. Such first elastic element <NUM> is positioned between the abutting undercut <NUM> and the flange <NUM>, so that the elasticity of the first elastic element <NUM> allows the flow adjustment solenoid valve <NUM> to arrange itself in the intermediate opening configuration.

In particular, in the intermediate opening configuration, the pump group <NUM> is operational, and the elasticity of the first elastic element <NUM> allows the partial lifting of the shutter <NUM> so as to partialize the flow rate of the infusion fluid from the pump group <NUM> to the dispensing group <NUM>.

Preferably, the tubular element <NUM> is removably engaged to the valve body <NUM>. For example, in the case of a threaded connection between the tubular element <NUM> and the valve body <NUM>, it is possible to screw the annular portion <NUM> into the annular wall <NUM>' so as to reduce the volume of the flow adjustment chamber <NUM> and increase the pre-compression of the first elastic element <NUM>, or it is possible to unscrew the annular portion <NUM> from the annular wall <NUM>' so as to disassemble the flow adjustment solenoid valve <NUM> and replace the first elastic element <NUM>.

According to one embodiment, the first elastic element <NUM> is a coil spring that operates under loads between <NUM> and <NUM> grams.

Preferably, when the flow adjustment solenoid valve <NUM> is in the closing configuration, the first elastic element <NUM> is precompressed.

In particular, the elastic constant of the first elastic element <NUM> is lower than the elastic constant of the second elastic element <NUM>. In other words, the second elastic element <NUM> is stiffer than the first elastic element <NUM>.

Advantageously, the first elastic element is easily replaceable in case its stiffness needs to be increased or reduced or in case of breakage. In addition, due to the ease with which the flow adjustment solenoid valve may be disassembled, an operator may easily separate the tubular element from the valve body and replace the first elastic element.

According to one embodiment shown in the attached <FIG>, the flow adjustment means <NUM> also comprise a first insert <NUM> that is removably engageable within the inlet chamber <NUM>. The insert has a first through-hole <NUM> for the passage of the infusion fluid.

This first through-hole <NUM> is occluded by the shutter <NUM> in the closing configuration and is defined by a first hole diameter D1 suitable for allowing the flow of the infusion fluid to lift the shutter and move it from the closing configuration to the intermediate opening configuration.

In other words, through the length of the first hole diameter, it is possible to obtain the desired pressure and velocity values of the infusion fluid, so that the obtained flow is able to lift the shutter and arrange the flow adjustment solenoid valve in the intermediate opening configuration.

According to one embodiment, the inlet chamber <NUM> comprises an access opening 412b facing outwards from the valve body <NUM> and suitable for allowing the adjustment of the axial position of the first insert <NUM> along the inlet chamber <NUM> and/or the replacement of the first insert <NUM> without disassembling the flow adjustment solenoid valve <NUM>.

Advantageously, the first insert may be accessed through the access opening so that its position along the valve axis may be regulated. By moving the first insert toward the shutter, the pre-compression of the first elastic element may be increased. Conversely, moving the first insert axially away from the shutter reduces the pre-compression of the first elastic element in the closing configuration. In particular, by controlling the pre-compression of the first elastic element, a micro-adjustment of the flow of the infusion fluid may be achieved, as increasing the pre-compression results in greater resistance to the passage of the infusion fluid, which leads to a change in the pressure and velocity of the infusion fluid.

In the present case, moving the first insert toward the shutter and thus increasing the pre-compression of the first elastic element increases the resistance to the passage of the infusion fluid and decreases the fluid pressure, for example, the pressure is less than <NUM> bar. Conversely, moving the first insert away from the shutter and thus reducing the pre-compression of the first elastic element decreases the resistance to the passage of the infusion fluid and increases the fluid pressure, e.g., the pressure is above <NUM> bar.

As also shown in <FIG>, the access opening also allows the first insert to be replaced in the case of breakage or if a first insert with a different length of the first hole diameter is desired.

Advantageously, by choosing the first insert with the desired length of the first hole diameter, it is possible to obtain certain pressure and speed values of the infusion fluid, so that the obtained flow is able to lift the shutter and arrange the flow adjustment solenoid valve in the intermediate opening configuration.

In other words, by appropriately choosing the first insert, a flow macro-adjustment may be achieved, because through the length of the first hole diameter, the desired pressure and speed values of the infusion fluid may be obtained.

According to an example embodiment shown in <FIG>, the flow adjustment solenoid valve <NUM> comprises a cap <NUM> to removably close the access opening 412b.

By removing the cap <NUM>, it is possible to access the first insert <NUM> and regulate its axial position (flow micro-adjustment) or replace it (flow macro-adjustment).

In one embodiment, the inlet chamber <NUM> is defined by a first pipe <NUM> extending along a fluid inlet axis I, and a second pipe <NUM> extending along the valve axis V.

The valve axis V is incident to the fluid inlet axis I. Preferably, the valve axis V is orthogonal to the fluid inlet axis I so as to form an inlet chamber <NUM> substantially in the shape of a T (<FIG>) or L (<FIG>).

The first pipe <NUM> has an inlet mouth <NUM>' suitable for receiving the infusion fluid pumped by the pump group <NUM>, and a connection mouth <NUM>" for connection with the second pipe <NUM>.

The second pipe <NUM> extends between a first end <NUM>' and a second end <NUM>" opposite the first, where that second end <NUM>" has an opening 412a facing the flow adjustment chamber <NUM> and suitable for being occluded by the shutter <NUM> in the closing configuration.

Preferably, the connection mouth <NUM>" flows into an intermediate portion of the second pipe <NUM>, i.e., between the first <NUM>' and the second end <NUM>". Alternatively, the connection mouth <NUM>" opens at the first end <NUM>' (<FIG>).

According to one embodiment, the access opening 412b delimits axially the first end <NUM>', and, at the second end <NUM>", the first insert <NUM> is placed. In particular, the first insert <NUM> is placed at the opening 412a.

In one embodiment, the flow adjustment means <NUM> also comprise a second insert <NUM> removably engageable inside the inlet chamber <NUM> so that it may be replaced without disassembling the flow adjustment solenoid valve <NUM>. Preferably, the second insert <NUM> is arranged inside the first pipe <NUM> in the vicinity of the connection mouth <NUM>".

Said second insert <NUM> has a second through-hole <NUM> for the passage of the infusion fluid, and said second through-hole <NUM> is defined by a diameter D2 that allows the regulation of the pressure and speed of the infusion fluid.

In detail, the first pipe <NUM> exhibits at least one taper proceeding axially along the fluid inlet axis I from the inlet mouth <NUM>' to the connection mouth <NUM>". Such taper defines a second seat in which to house the second insert <NUM>, for example, by shape and/or force coupling, or by threaded connection.

According to an embodiment illustrated in <FIG>, the flow adjustment means <NUM> also comprise an upper flow adjustment member <NUM>, such as a lever or a handle, integral to the first core <NUM>. By actuating the upper flow adjustment member <NUM>, the first core <NUM> moves along the valve axis V and moves the tubular element <NUM>, so that the annular portion <NUM> of the tubular element <NUM> engages the annular wall <NUM>' of the valve body <NUM> more deeply, causing an increase in the pre-compression of the first elastic element <NUM>.

For example, by rotating the handle, the rotation is transferred from the first core <NUM> to the tubular element <NUM>, the annular portion <NUM> of which screws deeper into the annular wall <NUM>' of the valve body <NUM>.

Advantageously, screwing the annular portion into the annular wall reduces the volume of the flow adjustment chamber and increases the pre-compression of the first elastic element. Said pre-compression defines the force with which the shutter occludes the infusion fluid passage and enables a micro-adjustment of the flow, because it allows the pressure and speed of the infusion fluid to be adjusted when the flow adjustment solenoid valve is in the intermediate opening configuration.

According to one embodiment illustrated in the attached <FIG>, the flow adjustment means <NUM> comprise a pair of programmable magnets <NUM>, where a first magnet <NUM> of said pair of programmable magnets <NUM> is fixed to the tail end <NUM>", and a second magnet <NUM> of said pair of programmable magnets <NUM> is fixed and made integral to the first core <NUM> so as to be facing the first magnet <NUM>. The flow adjustment solenoid valve <NUM> is powered by an electric motor that controls the rotation about the valve axis V of the first core <NUM>.

The rotation of the first core <NUM> is then transferred to the second magnet <NUM>, which rotates by a predefined first angle, so as to achieve angular alignment along the valve axis V between the first <NUM> and the second magnet <NUM>. Said angular alignment along the valve axis V allows the pair of programmable magnets <NUM> to behave like a spring and thus allows the flow adjustment solenoid valve <NUM> to arrange itself in an intermediate opening configuration.

For the purpose of this discussion, the term "programmable magnet" or "correlated magnet," or even simply "polymagnet" refers to a magnetic structure comprising a plurality of magnets of alternating polarity and variously arranged on a plane. By virtue of said plurality of magnets, extremely complex magnetic fields may be generated, and bringing a pair of programmable magnets closer together may result in different behaviors depending on how the polarities of the magnets that make up each programmable magnet are arranged.

In particular, programmable magnets have been the subject of a plurality of patents filed under the name "Correlated Magnetics Research," including <CIT>, <CIT> and <CIT>.

In the present case, considering a pair of programmable magnets facing each other and rotating the first magnet with respect to the second magnet, i.e., changing the axial angular alignment between the two magnets, three different responses may occur: attraction, rejecting and "spring" behavior.

In "spring" behavior, the two magnets stand at an equilibrium distance, and bringing them closer together it generates rejecting forces that tend to bring them back to the equilibrium distance. On the contrary, moving them away from each other creates attractive forces that tend to bring them back to the equilibrium distance.

In the embodiment shown in <FIG>, the first <NUM> and second <NUM> magnets are observed at the equilibrium distance, i.e., angularly aligned along the valve axis V so as to exhibit "spring" behavior.

Advantageously, through the planar arrangement of the plurality of magnets with alternating polarity that makes up each programmable magnet, it is possible to choose the pair of programmable magnets that exhibits the desired equilibrium distance. Specifically, at the equilibrium distance, the flow adjustment solenoid valve is arranged in the intermediate opening configuration, and by choosing the appropriate equilibrium distance, the desired flow of infusion fluid may be achieved.

According to an embodiment shown in <FIG>, the second magnet <NUM> rotates by a second predefined angle so as to achieve an angular alignment along the valve axis V between the first <NUM> and the second <NUM> magnet such that the pair of programmable magnets <NUM> may attract each other and arrange the flow adjustment solenoid valve <NUM> in a complete opening configuration. In other words, when the second magnet <NUM> rotates by an amplitude equal to that of the second predefined angle, the axial angular alignment of the pair of programmable magnets results in an attraction behavior between the first and second magnets.

In the embodiment shown in <FIG>, the second magnet <NUM> rotates by a predefined third angle so as to obtain an angular alignment along the valve axis V between the first <NUM> and the second <NUM> magnet such that the pair of programmable magnets <NUM> may repel each other and arrange the flow adjustment solenoid valve <NUM> into a closing configuration. In other words, when the second magnet <NUM> rotates by an amplitude equal to that of the predefined third angle, the axial angular alignment of the pair of programmable magnets results in rejecting behavior between the first and second magnets.

Specifically, the flow adjustment means <NUM> comprise the first elastic element <NUM> and/or the first insert <NUM> and/or the second insert <NUM> and/or the upper flow adjustment member <NUM> and/or the pair of programmable magnets <NUM>. The flow adjustment means <NUM> are suitable for regulating the flow of infusion fluid from the pump group <NUM> to the dispensing group <NUM> when the flow adjustment solenoid valve <NUM> is in the intermediate opening configuration.

Preferably, the flow adjustment solenoid valve <NUM> also comprises a coil <NUM> that, when current flows through it, generates a magnetic field that lifts the piston <NUM> due to the presence of the second core <NUM> that is made of a ferrous material. By lifting the piston <NUM>, the flow adjustment solenoid valve <NUM> is arranged in the complete opening configuration.

According to a different embodiment shown in the attached <FIG>, the piston <NUM> is at least partially a permanent magnet and the flow adjustment means <NUM> also comprise a permanent micro-adjustment magnet <NUM>' that is fixed and made integral to the first core <NUM>. Said permanent micro-adjustment magnet <NUM>' is facing the piston <NUM>, such that the facing polarities of the permanent micro-adjustment magnet <NUM>' and of the piston <NUM> are coincident.

Since the polarity of the permanent micro-adjustment magnet <NUM>' is facing and coincident with the polarity of the piston <NUM>, a rejecting force is generated on the piston <NUM>, which, as it moves away from the first core <NUM>, results in an increase of the force with which the shutter <NUM> occludes the passage of the infusion fluid.

With the flow adjustment solenoid valve <NUM> in the intermediate opening configuration, the higher the rejecting force the lower the infusion fluid flow rate. In fact, considering that the pressure of the infusion fluid determines the lifting of the shutter, the higher the rejecting force, the less the shutter <NUM> may be lifted; conversely, the lower the rejecting force, the more the shutter <NUM> may be lifted.

To reduce the rejecting force, the first core <NUM> may be moved along the valve axis V, so that the permanent micro-adjustment magnet <NUM>' is moved away from the piston <NUM>.

Advantageously, by adjusting the rejecting force between the permanent micro-adjustment magnet <NUM>' and the piston <NUM>, a micro-adjustment of the flow of the infusion fluid may be achieved. Specifically, increasing the rejecting force results in greater resistance to the passage of the infusion fluid, which leads to a change in the pressure and the velocity of the infusion fluid. Conversely, reducing the rejecting force also the resistance to the passage of the infusion fluid decreases.

It will appear obvious to the person skilled in the art that, in order to arrange the flow adjustment solenoid valve <NUM> in the complete opening configuration, the current must flow through the coil <NUM> so as to generate a magnetic field so as to overcome the rejecting force and lift the piston <NUM>.

Preferably, the piston <NUM> comprises the second core <NUM> which is a permanent magnet.

According to the attached figures, the directional arrows shown indicate the flow direction of the infusion fluid.

Innovatively, the infusion beverage dispensing machine achieves the intended object, as it allows the dispensing pressure to be controlled by the flow adjustment solenoid valve alone.

Advantageously, the machine that is the subject of the present invention is extremely versatile, because in addition to the flow adjustment solenoid valve, the pressure and/or speed of the infusion fluid may also be regulated through the pump group. In other words, the synergic combination of the pump group with the flow adjustment solenoid valve allows the pressure of the infusion fluid to be varied while dispensing the infusion beverage.

According to an advantageous aspect, the machine that is the subject of the present invention is compact because the flow adjustment means are fully integrated into the flow adjustment solenoid valve. In other words, the control board and pressure transducer are not necessary to carry out the adjustment of the dispensing pressure.

According to an even further advantageous aspect, the machine that is the subject of the present invention allows operation under both "low flow" and "full flow" conditions, i.e., it allows adjustment of the flow rate of the infusion fluid during each phase of infusion of the organic substance (e.g., blooming, pre-infusion, dispensing, end of dispensing).

Claim 1:
A machine (<NUM>) for dispensing an infusion beverage, such as coffee, chamomile, tea, or herbal tea, comprising:
- a pump group (<NUM>), such as a rotary pump, suitable for pumping an infusion fluid;
- a dispensing group (<NUM>) arranged downstream of the pump group (<NUM>) and fluidly connected to it, said dispensing group (<NUM>) comprising a filtration member suitable for containing an organic substance wettable by the infusion fluid so as to obtain the corresponding infusion beverage to be dispensed;
- a flow regulation solenoid valve (<NUM>) extending along a valve axis (V) and which is fluidly interposed between the pump group (<NUM>) and the dispensing group (<NUM>) so as to control the flow of the infusion fluid, said flow adjustment solenoid valve (<NUM>) comprises a shutter (<NUM>) which is movable along the valve axis (V) and configurable in a closing configuration, in which the pump group (<NUM>) is inactive and the shutter (<NUM>) blocks the passage of the infusion fluid from the pump group (<NUM>) to the dispensing group (<NUM>), and in a complete opening configuration, in which the pump group operates and the shutter (<NUM>) is completely lifted so as to allow the infusion fluid to reach the dispensing group,
Characterized by the fact that the flow adjustment solenoid valve (<NUM>) comprises flow adjustment means (<NUM>) suitable for adjusting the passage of the infusion fluid, and wherein, between the closing configuration and the complete opening configuration, the flow adjustment solenoid valve (<NUM>) is arranged in an intermediate opening configuration, in which the pump group (<NUM>) operates and the flow adjustment means (<NUM>) allow the partial lifting of the shutter (<NUM>) so as to partialize the flow of the infusion fluid from the pump group to the dispensing group.