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DESCRIPTION

Technical field

The present invention relates to a structure for dispensing metered amounts of at least one washing agent in a washing machine, in particular a laundry washing machine. Technological background

In the technical field of washing machines - and in particular in the technical field of laundry washing machines - the use of drawer structures is widely known, which are adapted to contain one or more washing agents, typically a laundry detergent and a softener, which are suited to be dispensed in a metered manner according to operating modes that are predetermined during a work cycle of the machine itself.

More in detail, these structures comprise a hollow shell, in which a drawer is mounted in a movable manner and defines one or more chambers, which are each adapted to act as a tank that is suited to receive the washing agent (laundry detergent or softener), typically in a quantity that is equal to a plurality of doses of said washing agent. Furthermore, the shell containing the drawer is generally mounted on a casing of the laundry machine, so as to be movable between an extracted position and a retracted position relative to the casing. In the extracted position, the chambers of the drawer open up outwards and are adapted to receive said quantity of laundry detergent and/or softener. In the retracted position, on the other hand, the chambers of the drawer are closed by the casing and are suited to dispense the aforesaid quantity of laundry detergent and/or softener during the work cycle through inner ducts of the machine towards the washing tank.

For this type of application, the washing agents used are typically available in a liquid form and, therefore, they are generally dispensed by means of a pumping apparatus, in particular of the hydraulic type. The pumping apparatus usually comprises a pair of electropumps , of which one is adapted to push a quantity of the liquid contained in the laundry detergent chamber, whereas the other one, in turn, is adapted to push a quantity of the liquid contained in the softener chamber. In use, these quantities are equal to the respective doses desired for the work cycle selected, whereas the remaining part of the laundry detergent and softener in the liquid form remains in the respective chambers so as to be used in following work cycles .

The pumping apparatus is generally controlled by an electronic control unit, which is arranged in the washing machine and is configured to be electrically connected to the electropumps so as to cause the laundry detergent and softener to be dispensed according to predetermined operating modes.

According to the prior art, an example of drawer is known, in which the electropumps are mounted inside the chambers and are electrically connected to the electronic control unit by means of a mechanical connection, which is interrupted every time the drawer is moved from the retracted position to the extracted position. Typically, this electric connection is performed by means electric connectors, which have a part that is mounted on the drawer, whereas the other part is mounted on the casing, these parts being able to be engaged and disengaged every time the drawer is moved to the retracted position and removed from the retracted position, respectively.

Though, the aforesaid example has some drawbacks.

One drawback is due to the fact that the electropumps are operatively immersed in the respective washing agents in the liquid form that are housed in the chambers.

This drawback implies not only a remarkable reduction of the liquid loading capacity inside the chambers. In fact, for reasons due to electric safety, manufacturers necessarily have to use an electropump provided with a DC and low-power electric motor, thus making the adoption of a power supplier indispensable, which causes the system to be more complicated. Furthermore, the electric wiring must be performed with expensive solutions, so as to ensure the reliability of the electric connection.

Another drawback is due to the fact that the electric connection is reversible and removable, in particular by means of electric connectors. In fact, the drawer, in use, is frequently moved to the retracted position and removed from it, thus involving a considerable risk that, in time, can lead to the electric connectors being affected by wear, which causes the electric connection between the electropumps and the control unit to be unreliable. This can cause serious faults and failures of the laundry machine .

Summary of the invention

An object of the present invention is to provide a drawer structure, which is able to ensure a safe and reliable electric connection between the electric motor and the electronic control unit. In particular, thanks to the present invention, this safety in the insulation of the electric connection enables the use not only of DC electropumps , but also of AC (for example 230 V) electropumps .

A further object of the present invention is to provide a drawer structure, which is able to ensure designing flexibility, especially by permitting the adoption of different building layouts of the pumping apparatus .

An additional object of the present invention is to provide a drawer structure, whose possibilities of mechanical connection to the casing and control unit are ergonomic .

According to the present invention, these and other objects are reached by means of a drawer structures having the features set forth in the appended independent claim.

The appended claims are an integral part of the technical teachings provided in the following detailed description concerning the present invention. In particular, the appended dependent claims define some preferred embodiments of the present invention and describe optional technical features.

Brief description of the drawings

Further features and advantages of the present invention will be best understood upon perusal of the following detailed description, which is provided by way of example and is not limiting, with reference, in particular, to the accompanying drawings, wherein:

- figure 1 is a schematic perspective view of a washing machine including a drawer structure manufactured according to an explanatory embodiment of the present invention;

- figure 2 is an exploded perspective view of the structure shown in figure 1; - figure 3 is a partial perspective view seen from above of a drawer of the structure shown in the previous figures;

- figure 4 is a rear perspective view of the drawer shown in figure 3 ;

- figure 5 is an exploded perspective view seen from the back of a part of the drawer shown in figures 3 and 4;

- figure 6 is a front perspective view of a part of a shell of the structure shown, in particular, in figure 2 ;

- figure 7 is a rear perspective view of the shell shown in figure 6 ;

- figure 8 is an exploded perspective view seen from the back of a part of the shell shown in figures 6 and 7;

- figures 9 and 10 are partial longitudinal section views of the structure, in which portions of the drawer and of the shell shown in the previous figures are visible;

- figure 11 is a rear perspective view of a shell of a drawer structure manufactured according to a further exemplary embodiment of the present invention;

- figure 12 is a rear perspective view of a shell of a drawer structure manufactured according to another embodiment of the present invention;

- figure 13 is a rear perspective view of a drawer of the structure shown in figure 12; and

- figure 14 is a front perspective view of a part of the shell shown in figure 12.

Detailed description of the invention

With reference to the figures from 1 to 9, number 10 indicates, as a whole, a drawer structure manufactured according to an explanatory embodiment of the present invention. As explained more in detail in the following description, drawer structure 10 is intended to dispense metered amounts of at least one washing agent in a washing machine, in particular a laundry washing machine.

As you can see, drawer structure 10 is represented, by way of example, as built-in in a laundry washing machine M. Though, in further variants, this drawer structure can be applied to washing machines of different types, for example to a dishwasher.

In figure 1, laundry machine M has a casing C, in which there is defined a washing tank, in which a drum or basket is supported in a rotary manner so as to hold the clothes to be washed (details with no reference numbers) . In particular, laundry washing machine M is, by way of example, a front-loading laundry machine having a loading opening, on which there is fitted a door D (optionally provided with a transparent window) , which is hinged to a front wall FW of casing C and through which the clothes can be introduced into the drum. Though, the present invention can be equally applied also to laundry washing machines of different types, for example top-loading laundry washing machines, optionally provided with doors of different types.

In this embodiment, drawer structure 10 is fitted on the front face or wall FW of casing C of laundry washing machine M, for example arranged above the washing tank (and, thus, above door D) . Though, as a person skilled in the art can easily understand, this arrangement of drawer structure 10 should not be interpreted as limiting for the scope of protection of the present invention.

With reference, in particular, to the figures from 2 to 4, drawer structure 10 comprises:

- a hollow shell 12 or "drawer carrier", which is intended to be fitted on casing C of the washing machine M; and - a drawer 14, which defines a pair of chambers 16a, 16b, each of which is suited to receive a washing agent, drawer 14 being mounted so as to move in shell 12 between an extracted position, in which each chamber 16a, 16b can be accessed through shell 12 and is ready to receive the washing agent, and a retracted position, in which each chamber 16a, 16b is closed by shell 12 and is suited to dispense said washing agent to the outside of structure 10.

In particular, the movement of drawer 14 in shell 12 takes place in a guided manner, for example as a translation movement in a direction that - in use - is substantially horizontal. Though, guided movements of different types can be provided, for example in the form of a rotation or oscillation of the drawer in shell 12.

In this embodiment, with reference, in particular, to the figures from 2 to 4, drawer 14 defines as a whole two chambers, in particular a laundry detergent chamber 16a and a fabric softener chamber 16b. Though, as a person skilled in the art can easily understand, in further embodiments the drawer can also define a single chamber or a number of chambers greater than two. In particular, with reference to figure 4, drawer 14 is shown represented from the back and with the rear delimiting wall represented in transparency, so as to clearly show the great number of components of structure 10.

As shown, for example, in figures 3 and 4, structure 10 comprises, furthermore:

- a pair of passages 17a, 17b, each of which is adapted to communicate, on one side, with a respective chamber 16a, 16b and, on the other side, with the outside of structure 10 (in particular, towards the washing tank of laundry washing machine M) , and - a respective pair of pumping members 18a, 18b, each of which is suited to push a quantity of the washing agent contained in a respective chamber 16a, 16b through the respective passage 17a, 17b and, therefore, towards the outside of structure 10 (and, especially, towards the washing tank of laundry washing machine M) .

As shown, in particular, in figures 2, 7 and 8, the structure comprises, furthermore, an electric motor 20, which is suited to operate pumping members 18a, 18b and is adapted to be connected to an electronic control unit of the washing machine.

As a person skilled in the art can easily understand, alternative embodiments are possible, in which the drawer has a single chamber and, in this case, only one passage and one pumping member are necessary. Vice versa, further embodiments are possible, in which a larger number of chambers are provided compared to the pair of chambers described with reference to the embodiment shown in the figures; even in this case a person skilled in the art is aware of the fact that, in order to adjust to these embodiments, a corresponding plurality of passages and associated pumping members must be provided.

Electric motor 20 is fixed on casing 12 and is separate from drawer 14. Furthermore, each pumping member 18a, 18b is able to assume

an active condition, in which it is coupled to motor 20 and to respective passage 17a, 17b, thus allowing the aforesaid quantity of washing agent to be dispensed, when drawer 14 is in the retracted position, and

an inactive condition, in which it is uncoupled from at least one between motor 20 and passage 17a, 17b, thus preventing the aforesaid quantity of washing agent from being dispensed, when drawer 14 is in the extracted position .

In this embodiment, in the inactive condition, pumping member 18a, 18b is uncoupled from motor 20.

In this way, structure 10 is able to ensure a safe and reliable electric connection between motor 20 and the electronic control unit. As a matter of fact, every time drawer 14 moves from the retracted position to the extracted position, this electric connection is substantially not affected. On the contrary, in this embodiment, the movement of drawer 14 between the retracted position and the extracted position simply implies a coupling and uncoupling, in particular of a mechanical nature, between motor 20 and pumping members 18a, 18b.

Besides, an electric insulation between drawer 14 and motor 20 is provided, since the electrically conductor elements of motor 20 are in a space that is separate and unaccessible relative to chambers 16a, 16b of drawer 14; this simultaneously implies that there is a greater space available in chambers 16a, 16b, so that they can house a larger quantity of washing agent (in this case, laundry detergent and/or softener) .

Furthermore, the presence of a single removable constraint, preferably of a substantially mechanical nature, between motor 20 and pumping member 18 permits a simplified and ergonomic operating mode for a user who uses a laundry washing machine M provided with drawer structure 10, without the need to control, every time the machine is used, whether an electric connection/disconnection of motor 20 has actually taken place.

This removable constraint can be of different types, for example kinematic, dynamic (force-based), geometric (shape-based), so that, in the active condition, an electrically controlled operation of motor 20 corresponds to an associated rotation of desired pumping member 18a, 18b .

A further optional advantage that can be obtained with the present invention lies in the fact that drawer 14 can be completely extracted from the shell in a simple manner, for example for cleaning or washing operations to be performed on the drawer, without having to worry about preserving the integrity of possible connectors of electric contacts .

Always with reference to the embodiment shown, in particular, in the figures from 2 to 4, you can see that each pumping member 18a, 18b is mounted so as to be integral to drawer 14 during its movements between the retracted position and the extracted position. In particular, during the movement between the retracted and extracted position of drawer 14, each one of pumping members 18a, 18b remains coupled to the respective passage 17a, 17b, whereas the coupling and uncoupling take place between corresponding pumping member 18 and motor 20.

With reference, in particular, to figures 5, 6, 9 and 10, we are going to describe a preferred way in which each pumping member 18a, 18b can be coupled to motor 20.

In this embodiment, there is a single motor 20, which is provided with a pair of output shafts 22a, 22b and with an appropriate transmission mechanism 24, adapted to selectively control the power delivered by output shafts 22a, 22b. Each one of output shafts 22a, 22b is adapted to be inserted into a corresponding seat 26a, 26b, which is obtained in respective mobile pumping member 18a, 18b. In particular, each output shaft 22a, 22b has a shaped section (for example with a multi-lobed shape or a star shape), adapted to engage seat 26a, 26b with a corresponding shape, when drawer 14 moves to the retracted position.

In this embodiment, the coupling between each output shaft 22a, 22b and respective seat 26a, 26b is adapted to take place in a dampened manner. Preferably, each seat 26a, 26b is torsionally supported, in particular thanks to a respective elastic member 28a, 28b, by the respective mobile pumping member 18a, 18b. In this way, in particular thanks to the above-mentioned torsional clearance, the coupling between each output shaft 22a, 22b and respective seat 26a, 26b becomes easier, even if their complementary shapes are not perfectly aligned when drawer 14 is pushed to the retracted position.

In the embodiment shown, each seat 26a, 26b is obtained on a cup-shaped element (with a shape that is complementary to the one of respective output shaft 22a, 22b) , which is housed in a turning manner and can be rotated in the central position of mobile member 18a, 18b in a torsionally constrained manner, in particular by means of elastic member 28a, 28b (for example a properly preloaded helical spring) .

In the embodiment shown, a single motor 20 is provided to selectively control each output shaft 22a, 22b by means of transmission mechanism 24, in particular of the clutch type. More in detail, transmission mechanism 24 can be engaged by means of an electric command, so as to selectively activate, one at a time, the desired output shaft 22a, 22b. In particular, transmission mechanism 24 comprises an oscillating lever 29, which tends to elastically hold (see, for example spring 30 acting upon said lever 29), in a engaging or meshing manner, an output shaft 22a with electric motor 20 and is adapted to be moved so as to engage or mesh with the other output shaft 22b due to the action of an electromagnetic actuator 31, which is suited to be electrically supplied with power by the electronic control unit of the laundry washing machine and is designed to push oscillating lever 29. The activation of electromagnetic actuator 31 causes an oscillation of oscillating lever 29, in particular having the shape of a rocker arm, which brings the gear clutch to a condition such as that output shaft 22b meshes with the motor. Vice versa, upon deactivation of electromagnetic actuator 31, spring 30 tends to bring oscillating lever 29 back to a position in which it is arranged so as to mesh with output shaft 22a.

In the embodiment shown, oscillating lever 29 comprises a rocker arm, which is hinged to shell 12, for example about a substantially vertical rotation axis. Rotation axis 29 preferably intersects the rotation axis of electric motor 20, which means that it substantially is in a central and intermediate position between the two output shafts 22a, 22b.

In the embodiment shown, electromagnetic actuator 31 comprises a ferromagnetic core 31a, which can be excited by a solenoid (not shown), which is connected to an arm 29b of the rocker arm offered by oscillating lever 29. In particular, ferromagnetic core 31a is constrained to arm 29b, which is pushed by spring 30, whereas the associated solenoid is able to attract ferromagnetic core 31a when it is excited by an electric current. In this way, ferromagnetic core 31a is able to cause arm 29b to lower against the action of spring 30, thus causing transmission mechanism 24 to engage output shaft 22b and, at the same time, raising opposite arm 29a (which, in turn, disengages transmission mechanism 24 from output shaft 22a) .

Preferably, transmission mechanism 24 comprises a plurality of gears (with no reference numbers), which cooperate with single motor 20 so as to allow motion to be transferred to output shafts 22a, 22b in a manner that is appropriate to provide the necessary power to pumping members 18a, 18b.

Preferably, each one of passages 17a, 17b comprises a deformable tube 33a, 33b and each pumping member 18a, 18b comprises a peristaltic rotor 35a, 35b, adapted to hydraulically cooperate with respective deformable tube 33a, 33b so as to push the washing agent contained in corresponding chamber 16a, 16b.

In the embodiment shown, peristaltic rotor 35a, 35b comprises a pair of projecting portions (with no reference numbers), which are preferably arranged on diametrically opposite sides adapted to be arranged in contact with the walls of deformable tube 33a, 33b. In particular, these projecting portions are adapted to create a local narrowing obtained on deformable tube 33a, 33b, and adapted to cause the fluid contained therein to move forward during the rotation of peristaltic rotor 35a, 35b. Preferably, at least one of these projecting portions comprises a peripheral roller, capable of locally compressing deformable tube 33a, 33b, thus generating a consequent narrowing on the latter.

In particular, in this embodiment, each seat 26a 26b is preferably obtained on a cup-shaped element, which is housed and able to rotate (in a torsionally constrained manner) in a substantially central position of the associated peristaltic rotor 35a, 35b. In this embodiment, each one of passages 17a, 17b comprises a respective duct 37a, 37b, preferably substantially rigid, which is adapted to suck the fluid from the bottom of corresponding chamber 16a, 16b and communicates with the inlet of associated deformable tube 33a, 33b. In particular, each duct 37a, 37b is substantially L-shaped, since it preferably starts, with an ascending segment, from the bottom of associated chamber 16a, 16b and ends in a substantially horizontal segment, thus joining deformable tube 33a, 33b.

In this embodiment, each pumping member 18a, 18b (in particular, each peristaltic rotor 35a, 35b) can rotate about a horizontal rotation axis.

In this embodiment, motor 20 is mounted in correspondence to rear wall 32 of shell 12, in particular on the outer face thereof. More in detail, each one of output shafts 22a, 22b projects towards the inner cavity of shell 12, thus extending through rear wall 32.

In this embodiment, with reference, in particular, to figure 5, pumping members 18a, 18b (in particular, peristaltic rotors 35a, 35b) and respective passages 17a, 17b (in particular, deformable tubes 33a, 33b) associated therewith are enclosed, on the rear side, in drawer 14, in particular by a rear wall 34. Preferably, rear wall 34 has a pair of openings 36, through which output shafts 22a, 22b are able to be coupled to pumping members 18a, 18b, in particular in correspondence to seats 26a, 26b.

In the embodiment shown, with reference, in particular, to figure 3, each passage 17a, 17b is adapted to drain the quantity of washing agent drawn from associated chamber 16a, 16b through an intermediate hollow space 38, which is obtained in drawer 14 and communicates with the outside through proper openings, which are obtained, for example, on the bottom of shell 12 (details not visible), when drawer 14 is in the retracted position. In particular, intermediate hollow space 38 is delimited by partitions or dividing walls (with no reference numbers), which are arranged between chambers 16a, 16b and pumping members 18a, 18b.

With reference to the figure 11, number 110 indicates, as a whole, a drawer structure manufactured according to a further explanatory embodiment of the present invention.

Details and elements that are similar to those of the embodiment described above - or fulfill a similar function - are associated with the same alphanumeric references. For the sake of brevity, the description of these details and elements will not be repeated below, but reference is made to what was previously explained in the description of the first embodiment.

Unlike the embodiment described in the previous figures, structure 110 comprises a pair of motors 120a, 120b, which are independent of one another and are fitted on shell 12. In this way, in order to operate each pumping member 18a, 18b so that it pushes the washing agent contained in the respective chamber 16a, 16b, the corresponding motor 120a, 120b simply needs to be electrically activated in a selective manner. In this case, each motor 120a, 120b controls the rotation of the respective output shaft 22a, 22b. Therefore, the presence of the clutch transmission mechanism 24 to alternately transfer motion to pumping members 18a, 18 is avoided.

The other features concerning the embodiment shown in figure 11 are substantially the same as the ones described in the embodiment shown in the figures from 1 to 10; therefore, for the sake of brevity, they will not be repeated below, but reference is made to the paragraphs of the description above.

With reference to the figures from 12 to 14, number 210 indicates, as a whole, a drawer structure manufactured according to another explanatory embodiment of the present invention .

Details and elements that are similar to those of the embodiment described above - or fulfill a similar function - are associated with the same alphanumeric references. For the sake of brevity, the description of these details and elements will not be repeated below, but reference is made to what was previously explained in the description of the previous embodiments.

Similarly to the embodiment shown in figure 10, this embodiment preferably - but not necessarily - comprises a structure with two motors 120a, 120b, each of which separately and independently controls the output shafts (in this case without reference numbers) . Actually, the single- motor structure described with reference to the embodiment shown in the figures from 1 to 9 could also be applied, thus providing a transmission mechanism, which is adapted to selectively transfer motion from the motor to one or the other output shaft in an alternative manner.

Unlike the embodiments described above, when drawer 14 is in the extracted position, each pumping member 18a, 18b is in the inactive condition, in which it is uncoupled from respective passage 17a, 17b, thus preventing a quantity of washing agent from being dispensed.

To sum up, in this embodiment, the movement of drawer

14 between the retracted position and the extracted position simply implies a coupling and uncoupling of a substantial hydraulic nature between pumping members 18a, 18b and respective passages 17a, 17b.

In other words, in the active condition, by (hydraulic) coupling between each pumping member 18a, 18b and respective passage 17a, 17b we mean a mutual arrangement thereof that is able to deliver energy to the fluid capable of flowing through passage 17a, 17b during the activation of the motor 20a, 20b. In this way, we obtain a hydraulic cooperation that is adapted to exert a head upon the fluid so as to cause it to be drawn from associated chamber 16a, 16b and transferred to the outside through passage 17a, 17b.

In this embodiment, the aforesaid hydraulic cooperation takes place by means of the narrowing, which is provoked by each peristaltic rotor 35a, 35b on respective deformable tube 33a, 33b, for example on diametrically opposite sides of peristaltic rotor 35a, 35b, during the rotation exerted by motor 20a, 20b.

Similarly, in the inactive condition, by (hydraulic) uncoupling between each pumping member 18a, 18b and respective passage 17a, 17b we mean a mutual arrangement thereof that is able to separate them and pull them apart. In particular, this mutual arrangement is nor able to deliver energy to the fluid capable of flowing through passage 17a, 17b during the activation of motor 20a, 20b. In this way, there is no hydraulic cooperation between passage 17a, 17b and relative pumping member 18a, 18b and, therefore, no head is exerted upon the aforesaid fluid so as to cause it to be drawn from associated chamber 16a, 16b and transferred to the outside through passage 17a, 17b.

In this embodiment, in the condition in which each passage 17a, 17b and respective pumping member 18a, 18b are uncoupled, the above-mentioned mutual arrangement takes place by detaching and pulling apart peristaltic rotor 35a, 35b from the contact with respective deformable tube 33a, 33b. In this way, during the rotation caused by motor 20a, 20b, peristaltic rotor 35a, 35b, despite being able to rotate, cannot act upon deformable tube 33a, 33b, since it is detached and not in contact on it any longer.

Preferably, each pumping member 18a, 18b is mounted at the output of respective motor 20a, 20b, in particular being steadily coupled - for example fitted flush - to the respective output shaft of said motor (without reference number) .

Therefore, each pumping member 18a, 18b - when drawer 14 moves to the retracted position - is caused to cooperate with respective passage 17a, 17b, which, even in this case, is integral to drawer 14 and, hence, close to respective pumping member 18a, 18b.

In this embodiment, in the active condition, each deformable tube 33a, 33b belonging to passage 17a, 17b is compressed against peristaltic rotor 35a, 35b created by pumping member 18a, 18b. In particular, each deformable tube 33a, 33b defines a cove, whose convexity horizontally faces peristaltic rotor 35a, 35b created by pumping member 18a, 18b. On the contrary, in the embodiment shown in the figures from 1 to 10, the cove defined by deformable tube 33a, 33b vertically faces peristaltic rotor 35a, 35b.

In this embodiment, each pumping member 18a, 18b (in particular, peristaltic rotor 35a, 35b) is mounted so as to rotate about a substantially vertical axis, which preferably coincides with the rotation axis of the output shaft of respective motor 20a, 20b.

If possible, the technical features differentiating the different versions of the embodiments described and illustrated above can freely be exchanged among said versions and embodiments.

Naturally, the principle of the present invention being set forth, the embodiments and the implementation details can be widely changed relative to what described above and shown in the drawings as a mere way of non- limiting example, without in this way going beyond the scope of protection provided by the accompanying claims.

For example, in further embodiments of the invention, the combination of passage 17a, 17b and pumping member 18a, 18b can be different from the peristaltic pump structure (including deformable tube 33a, 33b and peristaltic rotor 35a, 35b) suggested in the embodiments shown in the figures. In particular, the passage and the pumping member can be manufactured so as to create, on the overall, pump structures of different types, such as, by way of example, gear pumps, blade pumps, lobe pumps, screw pumps, etc..

Furthermore, in the embodiments shown, we discussed the use of a motor 20 or a plurality of motors 20a, 20b. In particular, for this motor or these motors, reference was made to apparatus that deliver, as an output, a rotary motion, for example by means of one or more output shafts. Though, as a person skilled in the art can easily understand, the aforesaid motors can be replaced or even combined with an actuator that is capable of delivering, as an output, a non-rotary motion (for example a translation motion) by means of a respective output member and can be coupled in an appropriate manner to one or more pumping members 18a, 18b, by means of suitable technical solutions. Therefore, according to the present invention, the drawer structure is compatible with any kind of moving means, including a motor and/or an actuator, which - at least in the active condition - are suited to control one or more pumping members.