The present invention relates to a refrigerating appliance.

More specifically, the present invention preferably relates to a foodstuff refrigerating appliance for domestic use, i.e. a fridge. Use to which the following description will make explicit reference without however losing in generality.

As is known, a fridge basically comprises: a substantially parallelepiped- shaped, outer casing which is internally provided with a thermal-insulated storage chamber adapted to accommodate perishable foodstuff and which communicates with the outside through a large access opening formed in the vertical front wall of the casing; a door with thermal-insulating structure which is usually flag hinged to the front wall of the casing so as to be manually movable about a vertical axis to and from a closing position in which the door abuts on the front wall of the casing for airtight closing the access opening of the storage chamber; and finally an electrically-operated, cooling system structured to keep the inside of the storage chamber at a given temperature suitable for preserving perishable foodstuffs and generally ranging between +2°C and +8°C.

In some fridges currently on the market, the cooling system comprises: a vertical air-circulating duct which is incorporated into a rear wall of the storage chamber, and communicates with the storage chamber via an air inlet located close to the ceiling of the storage chamber and via an air outlet located close to the bottom of the storage chamber; an electric fan which is accommodated inside the air-circulating duct, and is adapted to circulate a flow of air in closed loop along the air-circulating duct and the storage chamber; an electrically-operated, heat-pump assembly capable of cooling down the air flowing inside the air-circulating duct; and a central control unit capable of controlling both the electric fan and the heat-pump assembly for keeping the inside of the storage chamber at a given temperature selected by the user. More in detail, the evaporator of the heat-pump assembly is generally accommodated into the air-circulating duct for allowing the low-pressure and low- temperature refrigerant flowing through the evaporator to absorb heat from the air flowing through the air-circulating duct.

A fridge provided with this cooling system is disclosed in EP0793066 and in

EP1293739.

Aim of the present invention is to improve the air circulation inside the storage chamber so as to have a much more accurate control of the temperature distribution inside the storage chamber.

In compliance with the above aims, according to the present invention there is provided a refrigerating appliance comprising: at least one thermal-insulated storage chamber which is internally divided into two or more storage compartments each adapted to accommodate perishable foodstuff; and an electrically-operated, cooling system capable of cooling the inside of the storage chamber; the cooling system comprising: an air-delivery duct having an air inlet and at least two discrete air outlets all in fluid communication with the storage chamber, and wherein each of the at least two discrete air outlets is aligned to a single respective storage compartment for directing the air solely into the same storage compartment; an electric fan adapted to circulate a flow of air in closed loop along the storage chamber and the air-delivery duct; and an air-cooling device adapted to cool down the air flowing along the air- delivery duct; the refrigerating appliance being characterized in that a first discrete air outlet of the at least two discrete air outlets is dimensioned so that the ratio between the inner volume (measured in litres) of the storage compartment receiving the air from the first discrete air outlet and the overall cross sectional flow area (measured in mm ² ) of the first discrete air outlet is lower than the ratio between the inner volume of the at least one of the other/remaining storage compartment/s and the overall cross sectional flow area of the corresponding discrete air outlet.

It is underlined that in the present application the volumes are measured in Litres, and the areas in mm ² , and therefore the unit of measurement of the thresholds cited in the present application is Litres/mm ² . Preferably, the first discrete air outlet is dimensioned so that the ratio between the inner volume of the storage compartment receiving the air from the first discrete air outlet and the overall cross sectional flow area of the first discrete air outlet is lower than a given first threshold value.

More preferably, the first threshold value depends on the temperature and flow rate of the air circulating inside the air-delivery duct.

It is underlined that the temperature and flow rate of the air circulating inside the air-delivery duct depend mainly on the overall length of the air-delivery duct and on its cross section, on the heat exchange area of the air-cooling device (i.e. the area of the region of the air-cooling device which exchanges heat with the air in the air- delivery duct) and on its average temperature, on the average speed of the electric fan.

Preferably, the first threshold value is equal to 0.02.

In another advantageous embodiment, the first threshold is equal to 0.006.

Preferably, the first discrete air outlet is dimensioned so that the flow of cold air that comes out of the same first discrete air outlet and enters into the corresponding storage compartment keeps the inside of the same storage compartment at a temperature ranging between -2°C and +3°C.

Advantageously, the first discrete air outlet is dimensioned so that the ratio between the inner volume of the storage compartment receiving the air from the first discrete air outlet and the overall cross sectional flow area of the first discrete air outlet is greater than a given second threshold value lower than the first threshold value.

Advantageously, the second threshold value depends on the temperature and flow rate of the air circulating inside the air-delivery duct.

Preferably, the second threshold value is equal to 0.001.

More preferably, the second threshold value is equal to 0.002.

Even more preferably, the second threshold value is equal to 0.0025.

Advantageously, the/each remaining discrete air outlet of the at least two discrete air outlets is dimensioned so that the ratio between the inner volume of the storage compartment receiving the air from the remaining discrete air outlet and the overall cross sectional flow area of the remaining discrete air outlet is greater than a given third threshold value greater than the first threshold value.

Advantageously, the third threshold value depends on the temperature and flow rate of the air circulating inside the air-delivery duct.

Preferably, the third threshold value is equal to 0.03, more preferably to 0.04. Preferably, at least one of the discrete air outlets of the air-delivery duct is located on a rear wall of the storage chamber.

In an advantageous embodiment, one or more of the discrete air outlets of the air-delivery duct comprises a single opening or slot.

In a further advantageous embodiment, one or more of the discrete air outlets of the air-delivery duct comprises a plurality of openings or slots.

Advantageously, the opening/s or slot/s is/are arranged substantially astride the vertical midplane of the storage chamber.

Preferably, the air inlet of the air-delivery duct is located on a rear wall of the storage chamber.

Advantageously, the air inlet of the air-delivery duct comprises a plurality of openings or slots.

Preferably, the openings or slots are arranged substantially astride the vertical midplane of the storage chamber.

Advantageously, the first discrete air outlet is located downstream of the other/remaining discrete air outlet/s of the air-delivery duct with respect to the flowing direction of the air inside the air-delivery duct.

Preferably, the first discrete air outlet of the air-delivery duct has an overall cross sectional flow area greater than that of the second/remaining discrete air outlet/s.

Advantageously, the overall cross sectional flow area of the first discrete air outlet of the air-delivery duct is at least 50% greater than the overall cross sectional flow area of any other second/remaining discrete air outlet/s of the air-delivery duct.

Preferably, the storage compartment receiving the air from the first discrete air outlet of the air-delivery duct accommodates an extractable drawer.

Preferably, the first discrete air outlet of the air-delivery duct is shaped/structured so as to direct part of the airflow coming out from the same first discrete air outlet towards the outer surface of the drawer.

Advantageously, the air-delivery duct extends substantially vertically alongside the storage chamber.

Advantageously, the air inlet of the air-delivery duct is located close to the ceiling of the storage chamber.

Preferably, the air-delivery duct is integrated into a rear wall of the storage chamber.

Advantageously, the air-delivery duct is delimited by a rear wall of a substantially basin-shaped rigid inner shell delimiting the storage chamber, and by an inner partition septum or panel which extends inside the storage chamber locally adjacent and substantially parallel to a portion of the rear wall of the inner shell, so as to form a cavity or gap of given thickness.

Advantageously, the electric fan is accommodated inside the air-delivery duct, behind the air inlet of the air-delivery duct.

Preferably, the electrically-operated, cooling system comprises an electrically- operated, heat-pump assembly, and in the air-cooling device is the evaporator of the heat-pump assembly.

Advantageously, the electric fan is a variable-speed fan.

Preferably, the refrigerating appliance comprises an electronic control unit which controls the cooling system so as to keep the inside of the storage chamber at a given target temperature manually-selectable by the user; the electronic control unit being configured to force the electric fan to rotate at a predetermined low speed during normal working conditions, and to force the electric fan to rotate at a predetermined high speed during transient working conditions.

A non-limiting embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a household refrigerating appliance realized in accordance with the teachings of the present invention;

Figures 2 is a side view of the refrigerating appliance shown in Figure 1, sectioned along the vertical midplane of the refrigerating appliance and with parts removed for clarity; an enlarged detail is also shown;

Figure 3 is a perspective view of the storage chamber of the refrigerating appliance shown in Figures 1 and 2, sectioned along the vertical midplane of the same storage chamber and with parts removed for clarity; whereas Figure 4 is an enlarged view of the central portion of the storage chamber shown in Figure 3, with parts removed for clarity.

With reference to Figures 1 and 2, reference number 1 denotes as a whole a refrigerating appliance adapted for preserving perishable foodstuff and preferably suitable for domestic use, i.e. a fridge.

The refrigerating appliance 1 preferably comprises: at least one, preferably substantially parallelepiped- shaped, thermal-insulated storage chamber 2 adapted to accommodate perishable foodstuff; and an electrically-operated, cooling system 3 adapted to selectively cool down the inside of storage chamber 2 for keeping the inside of storage chamber 2 at a given target temperature, preferably suitable for long-life preservation of perishable foodstuff. Preferably this target temperature moreover ranges between -3°C and +8°C.

The refrigerating appliance 1 preferably basically comprises: a preferably substantially parallelepiped- shaped, outer casing 4 which is internally provided with at least one, preferably substantially parallelepiped-shaped, thermal-insulated storage chamber 2 preferably communicating with the outside through an access opening formed in the vertical front wall 5 of casing 4; and a door 6 having a thermal-insulating structure and which is preferably flag hinged to the front wall 5 of casing 4 so as to be manually movable about a preferably substantially vertically-oriented, reference axis A, to and from a closing position in which the door 6 abuts/rests on front wall 5 for substantially airtight closing the access opening of the storage chamber 2. The cooling system 3 is at least partially accommodated within the outer casing 4, preferably at least partially beside the storage chamber 2.

The outer casing 4 is preferably provided with two substantially parallelepiped- shaped, discrete storage chambers 2 and 2b which are preferably vertically aligned one another, and each of which preferably communicates with the outside through a corresponding, preferably substantially rectangular-shaped, access opening formed in the vertical front wall 5 of casing 4.

Preferably, the refrigerating appliance 1 comprises, for each storage chamber 2, 2b, a respective, preferably substantially rectangular- shaped, front door 6, 6b, which is preferably flag hinged to the front wall 5 of casing 4 at the side of the access opening of the corresponding storage chamber 2, 2b, so as to be manually movable about a common, vertically-oriented, reference axis A, to and from a closing position in which the door 6, 6b abuts/rests on front wall 5 for substantially airtight closing the access opening of the corresponding storage chamber 2, 2b.

The cooling system 3 is preferably structured to keep the upper storage chamber 2 at a given target temperature, preferably ranging -3°C and +8°C. Preferably the cooling system 3 is furthermore structured to keep the lower storage chamber 2b at a given target temperature lower than that of the upper storage chamber 2 and preferably, though not necessarily, ranging between -25°C and -10°C.

The outer casing 4 preferably comprises: a substantially parallelepiped-shaped, self-supporting boxlike cabinet 7 which is preferably made of metal material; a pair of substantially basin-shaped, rigid inner shells 8 which are preferably made of plastic or metal material and are stably accommodated/recessed inside the boxlike cabinet 7, in an upright position and one above the other, thus to form/delimit each a respective storage chamber 2, 2b of refrigerating appliance 1; and an intermediate thermal- insulating layer 9, which is preferably made of polymeric-material foam and is interposed between each inner shell 8 and the adjacent walls of boxlike cabinet 7 for minimizing heat exchange with the outside.

The lower storage chamber 2b of refrigerating appliance 1 preferably accommodates at least one, and preferably a number/plurality of, vertically- stacked, extractable, boxlike drawers 11 , each preferably made of plastic material and adapted to accommodate perishable foodstuff.

The upper storage chamber 2 of refrigerating appliance 1, is advantageously internally divided into a series of at least two, preferably vertically-aligned, storage compartments 12a and 12b, adapted to accommodate perishable foodstuff, preferably by means of a suitable number of horizontal partitioning shelves 13 vertically spaced apart inside the storage chamber 2, i.e. inside the inner shell 8 delimiting the storage chamber 2.

In the example shown, the storage chamber 2 is preferably internally divided into six vertically-aligned storage compartments 12a, 12b, 12c, 12d, 12e and 12f, preferably by means of five manually-replaceable, horizontal partitioning shelves 13, each preferably resting on a suitable number of supporting ledges protruding from the two reciprocally-faced, vertical lateral walls of the inner shell 8 delimiting the storage chamber 2.

The cooling system 3is advantageously structured to selectively channel a flow of cold air separately towards two or more of the storage compartments of storage chamber 2.

Preferably, the cooling system 3 basically comprises a, preferably substantially vertically-oriented, air-delivery duct 15, which extends within the casing 4 alongside the storage chamber 2, and communicates with the storage chamber 2 via an air inlet 16 and via a series of at least two discrete air outlets 17a, 17b, 17c, 17d, which are preferably located at different heights from the bottom of storage chamber 2, and which are each horizontally aligned to a respective storage compartment 12a, 12b, 12c, 12d of storage chamber 2 thus to direct the air solely into the same storage compartment 12a, 12b, 12c, 12d. In other words, for each storage compartment 12a, 12b, 12c, 12d there is a single one of the discrete air outlets 17a, 17b, 17c, 17d from which air exiting the air-delivery duct 15 enters directly such a storage compartment.

It is underlined that an air outlet 17a, 17b, 17c, 17d is to be intended as a restricted region on the inner wall of storage chamber 2 wherein cold air comes out of the air-delivery duct 15 and enters into a corresponding storage compartment 12a, 12b, 12c, 12d of storage chamber 2. Each air outlet 17a, 17b, 17c, 17d may consist of a single opening on the inner wall of storage chamber 2, or it may comprise a number/plurality of openings spaced to one another on the inner wall of storage chamber 2, but all arranged so as to channel the cold air directly and solely into a single storage compartment 12a, 12b, 12c, 12d of storage chamber 2. Preferably, the cooling system 3 also comprises: an electric fan 18 which is preferably accommodated inside the air-delivery duct 15 and is adapted to selectively circulate a flow of air in closed loop and in succession along the air-delivery duct 15 and the storage chamber 2; and an air-cooling device 19 which is preferably accommodated inside of, or immediately adjacent to the air-delivery duct 15, and is adapted to cool down the air that flows along the air-delivery duct 5.

Preferably, the air inlet 16 of air-delivery duct 15 is located on the rear wall 20 of storage chamber 2, and is preferably arranged roughly astride of the vertical midplane of the storage chamber 2.

Similarly, at least one of the two or more discrete air outlets 17a, 17b of the air-delivery duct 15 is located on the rear wall 20 of storage chamber 2, and is preferably also arranged roughly astride of the midplane of storage chamber 2.

A first air outlet 17a of the series of discrete air outlets of the air-delivery duct 15 is dimensioned so that the ratio between the inner volume of the corresponding storage compartment 12a and the overall cross sectional flow area of the same air outlet 17a is lower than the ratio between the inner volume of the other/remaining storage compartment 12b and the overall cross sectional flow area of the corresponding air outlet 17b of air-delivery duct 15; Applicant has found that this specific relation among above ratios is capable of keeping the inside of the storage compartment 12a at a temperature lower than that of the other/remaining storage compartment/s 12b of storage chamber 2.

Preferably, the air outlet 17a is dimensioned so that the ratio between the inner volume of the storage compartment 12a and the overall cross sectional flow area of the same air outlet 17a is lower than a given first threshold value, which preferably depends on the temperature and flow rate of the air circulating inside the air-delivery duct 15. Keeping this ratio below such a first threshold, allows keeping the inside of the storage compartment 12a at a temperature lower than that of the other/remaining storage compartment/s 12b, 12c, 12d (having an higher value of the same ratio) of storage chamber 2, and preferably ranging between -2°C and +3°C.

Advantageously, the lower is the temperature of the air circulation inside the air-delivery duct 15, and the higher is its flow rate, the higher is the value of the first threshold.

Preferably, the air outlet 17a is also dimensioned so that the ratio between the inner volume of the storage compartment 12a and the overall cross sectional flow area of the corresponding first air outlet 17a is greater than a given second threshold value which is lower than the first threshold value; Applicant has found that this ensures that the temperature within the storage compartment 12a is not too low, and in particular not low enough to freeze the perishable foodstuff accommodated in storage compartment 12a. Likewise the first threshold value, also the second threshold value preferably depends on the temperature and flow rate of the air circulating inside the air-delivery duct 15.

Advantageously, the lower is the temperature of the air circulation inside the air-delivery duct 15, and the higher is its flow rate, the higher is the value of the first threshold.

Experimental tests revealed that for an inner volume of the storage compartment 12a equal to 15 liters, an overall length of the air-delivery duct 15 equal to 810 mm, an average cross sectional area of the air-delivery duct equal to 9205 mm ² an heat exchange area of the air-cooling device 19 equal to 176400 mm ² , an average temperature of the air-cooling device 19 equal to -21 °C, an average speed of electric fan equal to 2000 rpm (round per minutes), an optimal value for the first threshold value is 0.006. In this case the optimum value of the ratio between the inner volume of the storage compartment 12a and the overall cross sectional flow area of the same air outlet 17a was identified as 0.00568, corresponding to an overall cross sectional flow area of the air outlet 17a equal to 2640 mm ² . In this case the second threshold value was identified as 0.002.

Other experimental tests revealed that for an inner volume of the storage compartment 12a equal to 15 liters, an overall length of the air-delivery duct 15 equal to 650 mm, an average cross sectional area of the air-delivery duct equal to 9205 mm ² , an heat exchange area of the air-cooling device 19 equal to 163800 mm ² , an average temperature of the air-cooling device 19 equal to -21 °C, an average speed of electric fan equal to 2000 rpm (round per minutes), an optimal value for the first threshold value is 0.02. In this case the optimum value of the ratio between the inner volume of the storage compartment 12a and the overall cross sectional flow area of the same air outlet 17a was identified as 0.01136, corresponding to an overall cross sectional flow area of the air outlet 17 equal to 1320 mm ² . In this case the second threshold value was identified as 0.0025.

In both the experimented cases, by dimensioning the air outlet 17a of air- delivery duct 15 so that the ratio between the inner volume of the storage compartment 12a and the overall cross sectional flow area of the same air outlet 17a is lower than the identified first threshold (and in particular was kept equal to the identified optimum value), and also preferably higher than the identified second threshold value, the inside of the storage compartment 12a was kept at a temperature lower than that of the other/remaining storage compartment/s 12 and in particular ranging between -2°C and +3°C.

In the example shown in attached figures, the air outlet 17a of air-delivery duct

15 is preferably dimensioned so that the ratio between the inner volume of the storage compartment 12a and the overall cross sectional flow area of the same air outlet 17a is lower than 0.015 and preferably also lower than 0.012.

The second/remaining air outlets 17b, 17c, 17d of air-delivery duct 15 are preferably dimensioned so that the ratio between the inner volume of the corresponding storage compartments 12b, 12c, 12d and the overall cross sectional flow area of the same air outlet 17b, 17c, 17d is greater than 0.04.

Preferably the air outlet 17a is located downstream of the second/remaining air outlets 17b, 17c, 17d of air-delivery duct 15 with respect to the flowing direction of the air inside the air-delivery duct 15.

In other words, the air outlet 17a is preferably the lowest air outlet of the series of discrete air outlets of the air-delivery duct 15, i.e. it is located at the lowest height from the bottom of storage chamber 2.

Preferably, but not necessarily, the air outlet 17a has an overall cross sectional flow area which is greater than that of the second/remaining air outlet/s 17b of air- delivery duct 15, so as to allow the air to come out of the air outlet 17a with a flow- rate greater than that of the air coming out of the second/remaining air outlet/s 17b, 17c, 17d.

Preferably, but not necessarily, the overall cross sectional flow area of the first air outlet 17a is at least 50% greater than the overall cross sectional flow area of the second/remaining air outlet/s 17b, 17c, 17d, so that the flow-rate of the air coming out of air outlet 17a is roughly at least 50% higher than the flow-rate of the air coming out of the second/remaining air outlet/s 17b, 17c, 17d.

With reference to Figures 2, 3 and 4, the air-delivery duct 15 is preferably provided with four discrete air outlets 17a, 17b, 17c and 17d, which are located at different heights from the bottom of storage chamber 2, each horizontally aligned to a corresponding storage compartment 12a, 12b, 12c and 12d of storage chamber 2 for directing the cold air solely into the same storage compartment 12a, 12b, 12c or 12d.

In other words, the air outlet 17a of air-delivery duct 15 is preferably horizontally aligned to storage compartment 12a of storage chamber 2 for directing the air solely into storage compartment 12a. The air outlet 17b is preferably horizontally aligned to storage compartment 12b of storage chamber 2 for directing the air solely into storage compartment 12b. The air outlet 17c is preferably horizontally aligned to storage compartment 12c of storage chamber 2 for directing the air solely into storage compartment 12c. The air outlet 17d is preferably horizontally aligned to storage compartment 12d of storage chamber 2 for directing the air solely into storage compartment 12d.

It is underlined that air, after having entered storage compartments 12a, 12b, 12c, 12d from respective air outlet 17a, 17b, 17c, 17d, can move also to another storage compartment; anyway any air outlet 17a, 17b, 17c, 17d leads directly into a single respective storage compartment.

Preferably the air outlet 17a of air-delivery duct 15 is therefore dimensioned so that the ratio between the inner volume of the corresponding storage compartment 12a and the overall cross sectional flow area of the same air outlet 17a is lower than the ratio between the inner volume of each remaining storage compartment 12b, 12c, 12d and the overall cross sectional flow area of the corresponding air outlet 17b, 17c, 17d of air-delivery duct 15, and more preferably also below the first threshold value, e.g. also lower than 0.015, and optionally also lower that 0.012, so that the increased flow of cold air entering into the storage compartment 12a is capable of keeping the inside of the storage compartment 12a at a temperature lower than that of each remaining storage compartment 12b, 12c, 12d, 12e and 12f of storage chamber 2 and preferably also ranging between -2°C and +3°C.

In the examples shown in attached figures, the air outlet 17a of air-delivery duct 15 is preferably dimensioned so that the ratio between the inner volume of the storage compartment 12a and the overall cross sectional flow area of the same air outlet 17a is preferably equal to 0.011 or equal to 0.0056.

Preferably the air outlet 17a is furthermore located downstream of the remaining air outlets 17b, 17c and 17d of air-delivery duct 15 with respect to the flowing direction of the air inside the air-delivery duct 15.

Each of the other air outlets 17b, 17c and 17d of air-delivery duct 15 is preferably dimensioned so that the ratio between the inner volume of the corresponding storage compartment 12b, 12c, 12d of storage chamber 2 and the overall cross sectional flow area of the same air outlet 17b, 17c, 17d is greater than 0.04.

More in detail, each of the other air outlets 17b, 17c and 17d of air-delivery duct 15 is preferably dimensioned so that the ratio between the inner volume of the corresponding storage compartment 12b, 12c, 12d of storage chamber 2 and the overall cross sectional flow area of the same air outlet 17b, 17c, 17d is preferably equal to 0.041 or equal to 0.047.

Preferably the refrigerating appliance 1 additionally comprises an electronic control unit 21 which is preferably recessed/ accommodated inside the outer casing 4, and is capable of controlling the cooling system 3, i.e. the electric fan 18 and preferably also the air-cooling device 19, so as to keep the inside of storage chamber 2 at a given first target temperature which is preferably manually-selectable by the user and preferably ranges between -3°C and +8°C. Optionally the electronic control unit 21 furthermore controls the cooling system 3 so as to keep the inside of storage chamber 2b at a given second target temperature which is preferably manually- selectable by the user and preferably ranges between -25 °C and -10°C.

More in detail, the electronic control unit 21 preferably monitors the temperature of the air inside storage chamber 2 and, if present, also inside storage chamber 2b preferably via a corresponding thermocouple or other temperature sensor (not shown in the figures), and selectively activates the cooling system 3 so as to continuously keep the inner volume of storage chamber 2 at first target temperature, and optionally so as to continuously keep the inner volume of storage chamber 2b at second target temperature.

In addition to the above, the electric fan 18 is preferably a variable- speed electric fan, and the electronic control unit 21 is capable of varying the rotation speed of the impeller of electric fan 18 preferably according to a particular control method set out below.

With reference to Figures 2 and 3, in the example shown, the air-delivery duct 15 is preferably substantially rectilinear and is preferably incorporated into the rear wall 20 of storage chamber 2. Furthermore the air inlet 16 is preferably located immediately underneath the ceiling 22 of storage chamber 2, and the electric fan 18 is preferably accommodated inside the air-delivery duct 15 immediately downstream of the air inlet 16.

Preferably the air outlet 17a of air-delivery duct 15 has an overall cross sectional flow area which is greater than that of any one of the remaining three air outlet 17b, 17c and 17d, so as to allow the air to freely come out of the air outlet 17a with a flow-rate significantly greater than that of the air coming out of any one of the remaining air outlet 17b, 17c and 17d.

In the example shown, the overall cross sectional flow area of the air outlet 17a of air-delivery duct 15 is preferably roughly 100% greater than the overall cross sectional flow area of any one of the remaining air outlet 17b, 17c and 17d of air- delivery duct 15.

Preferably the overall cross sectional flow areas of the remaining air outlets 17b, 17c and 17d are furthermore substantially equal to one another. Thus the flow- rate of the air coming out of air outlet 17a is preferably roughly equal to twice the flow-rate of the air coming out of any one of air outlets 17b, 17c and 17d.

The air inlet 16 of air-delivery duct 15 preferably comprises, or more preferably consists of, a plurality of, preferably substantially horizontally-oriented, and preferably also rectilinear, slots, which are arranged on the rear wall 20 of the storage chamber 2. Preferably these slots are vertically-staggered to one another, i.e. spaced side by side to one another, preferably immediately beneath the ceiling 22 of storage chamber 2 and preferably astride of the vertical midplane of the storage chamber 2.

The first air outlet 17a of air-delivery duct 15 preferably comprises, or more preferably consists of, a pair of preferably substantially horizontally-oriented and preferably also rectilinear slots, which are arranged on the rear wall 20 of the storage chamber 2 preferably vertically-staggered to one another, i.e. one side by side and above the other, preferably astride of the vertical midplane of storage chamber 2.

Each of the remaining air outlets 17b, 17c, 17d of air-delivery duct 15, instead, preferably comprises, or more preferably consists of, a single, preferably substantially horizontally-oriented and preferably also rectilinear, slot which is arranged on the rear wall 20 of storage chamber 2, preferably astride of the vertical midplane of storage chamber 2.

Obviously, according to an alternative embodiment, the air inlet 16 of air- delivery duct 15 and/or any one of the air outlets 17a, 17b, 17c, 17d of air-delivery duct 15 may comprise, or better may consist of, a number of small openings of any shape, preferably evenly spaced side by side to one another.

The air-delivery duct 15 is preferably formed/delimited by the, preferably roughly vertical, rear wall 8a of the inner shell 8 delimiting the storage chamber 2, and by an inner partition septum or panel 23 which extends inside the storage chamber 2, locally adjacent and substantially parallel to a portion of the rear wall 8a of the inner shell 8, so as to form a, preferably platelike, cavity or gap of given thickness.

Preferably, the partition septum 23 is firmly secured to the rear wall 8a, preferably by means of a suitable number of snap-fit tongues; preferably the horizontal width of partition septum 23 is preferably roughly equal to the horizontal width of rear wall 8a of inner shell 8, so that the air-delivery duct 15 substantially takes up the whole width of the rear wall 20 of storage chamber 2.

Moreover the air inlet 16 and the air outlets 17a, 17b, 17c and 17d of air- delivery duct 15 are preferably formed directly on partition septum 23.

In other words, the rectilinear slots forming the air inlet 16 and/or the air outlets

17a, 17b, 17c and 17d of air-delivery duct 15 are preferably pass-through slotted-hole/s directly realized in the body of partition septum 23.

Preferably the electric fan 18 is furthermore fitted into in the cavity or gap delimited by the inner partition septum 23 and by the adjacent rear wall 8a of inner shell 8, preferably immediately behind the air inlet 16.

Preferably, the storage compartment 12a associated to the air outlet 17a of air- delivery duct 15 accommodates at least one manually-extractable, boxlike drawer 24 which is preferably made of plastic material and is adapted to accommodate perishable foodstuff.

The air outlet 17a of air-delivery duct 15 is preferably shaped/ structured so as to direct part of the airflow coming out from the same air outlet 17a towards the outer surface of the drawer 24.

The air outlet 17a of the air-delivery duct 15 preferably comprises, or more preferably consists of, two horizontal and vertically- staggered slots formed on the rear wall 20 of storage chamber 2. The upper horizontal slot is arranged on the rear wall 20 of storage chamber 2, preferably immediately underneath the horizontal partitioning shelf 13 forming the ceiling of the storage compartment 12 accommodating the drawer 24, so as direct the air directly inside the adjacent drawer 24. The lower horizontal slot, instead, is preferably arranged on the rear wall 20 of storage chamber 2 directly faced to the rear wall of the drawer 24, so as direct the air against the rear wall of drawer 24.

The air-cooling device 19 is preferably firmly attached to the rear wall 8a of the inner shell 8 delimiting the storage chamber 2, outside of the same inner shell 8, so as to absorb heat from the air flowing inside the air-delivery duct 15, and preferably comprises, or more preferably consists of, the evaporator of an electrically-operated, heat-pump assembly 25.

In other words, the air-cooling device 19 is preferably the heat exchanger wherein the low-pressure and low-temperature refrigerant flowing towards the inlet/suction of the compressor of the heat-pump assembly absorbs heat from the surrounding environment, i.e. from the air flowing inside the air-delivery duct 15.

The cooling system 3 of refrigerating appliance 1 preferably includes an electrically-operated, heat-pump assembly 25 which preferably comprises: an electrically-operated compressor 26 which is preferably located into a compressor compartment formed on the bottom portion of outer casing 4, and is capable of compressing a low-temperature and low-pressure gaseous-state refrigerant for supplying at outlet a flow of high-temperature and high-pressure refrigerant; a first heat exchanger or condenser (non-shown in the figures), which is preferably attached to the rear wall of the outer casing 4, outside the same casing 4, and is structured so as to allow the high-temperature and high-pressure refrigerant arriving from compressor 26 to release heat to the outside environment; a refrigerant expansion device (non- shown in the figures) which is located inside the casing 4, and is capable of rapidly expanding the high-pressure refrigerant arriving from the condenser, so as to rapidly reduce both temperature and pressure of the refrigerant; and a second heat exchanger or evaporator, which actually corresponds to the air-cooling device 19, and is structured so as to allow the low-temperature and low-pressure refrigerant arriving from the refrigerant expansion device to absorb heat from the surrounding environment before returning back to the inlet/suction of compressor 26.

The heat-pump assembly 25 preferably additionally comprises: a third heat exchanger 27 or second evaporator, which is preferably located inside the lower storage chamber 2b, and is structured so as to allow the low-temperature and low- pressure refrigerant arriving from the refrigerant expansion device to absorb heat from the surrounding environment, i.e. from the inside of storage chamber 2b, before returning back to the inlet/suction of compressor 26; and a number of electrically controlled on-off valves (non-shown in the figures) for regulating the flow-rate of the refrigerant directed respectively towards evaporator 19 and evaporator 27. Electronic control unit 21 is preferably configured to selectively activate and deactivate the electric fan 18, the electrically-operated compressor 26 and, if present, also the on-off valves of heat-pump assembly 25, so as to keep the inside of storage chamber 2 at a given first target temperature which is preferably manually-selectable by the user and preferably ranges between -3°C and +8°C, and optionally also so as to keep the inside of storage chamber 2b at a given second target temperature which is preferably manually-selectable by the user and preferably ranges between -25 °C and - 10°C.

General operation of the refrigerating appliance 1 is easily inferable from the description above.

As regards the air-delivery duct 15, thanks to its increased overall cross sectional flow area with respect to the volume to cool down (i.e. the storage compartment 12a), the air outlet 17a of air-delivery duct 15 channels into the adjacent storage compartment 12a a flow of cold air, with respect to the volume to cool down, significantly greater than that of the air outlets 17b, 17c, and 17d, and is therefore able to keep the inner volume of the storage compartment 12a, which preferably contains the drawer 24, at a given temperature which is slightly lower than the average temperature of the rest of storage chamber 2 and preferably also roughly equal to 0°C.

Turning now to the control method implemented by control unit 21, in normal working condition the electronic control unit 21 monitors the temperature of the air inside storage chamber 2 and, if present, also inside storage chamber 2b preferably via a corresponding thermocouple or other temperature sensor (not shown in the figures), and selectively activates at same time both electric fan 18 and compressor 26, so as to continuously keep the temperature inside the storage chamber 2 at the target temperature selected by the user, or slightly below the target temperature.

Furthermore, in normal working conditions, the electronic control unit 21 preferably forces the electric fan 18 to rotate at a predetermined nominal low speed.

More in detail, when the temperature of the air inside storage chamber 2 raises up to reach the user-selected target temperature, the electronic control unit 21 activates at same time both electric fan 18 and compressor 26 so as to prevent any further increase of the temperature inside the storage chamber 2.

Instead, in transient working conditions, i.e. when the temperature of the air inside storage chamber 2 unexpectedly goes significantly higher than the user-selected target temperature, the electronic control unit 21 preferably forces the electric fan 18 to rotate at a given high speed, greater than the low speed.

More in detail, in transient working conditions the electronic control unit 21 of refrigerating appliance 1 preferably operates as follows.

When both compressor 26 and electric fan 18 are already working and the temperature of the air inside storage chamber 2 exceeds a first value linked to and greater than the user-selected target temperature, the electronic control unit 21 preferably forces the electric fan 18 to rotate at a given high speed, greater than the low speed.

Preferably, the electronic control unit 21 moreover reduces rotation speed of electric fan 18 to the low speed when the temperature of the air inside storage chamber 2 goes underneath a second value lower than the first value and again linked to and greater than the user-selected target temperature.

More in detail the first value is preferably equal to the user-selected target temperature plus a given first offset temperature. The second value, in turn, is preferably equal to the user-selected target temperature plus a given second offset temperature lower than the first offset temperature.

Furthermore, when the defrost phase of storage chamber 2 is completed, the electronic control unit 21 preferably activates both electric fan 18 and compressor 26 and forces electric fan 18 to rotate at the high speed, so as to bring the temperature of the air inside the storage chamber 2 as soon as possible back at the user-selected target temperature.

In addition to the above, preferably on request of the user, the electronic control unit 21 preferably activates both electric fan 18 and compressor 26 and forces electric fan 18 to rotate at high speed for a given time span preferably, though not necessarily, ranging between 5 to 15 minutes.

The advantages resulting from the particular structure of the air-delivery duct 15 of refrigerating appliance 1 are large in number.

First of all, the air-delivery duct 15 allows to obtain, inside storage chamber 2, at least two zones having microclimate different to one another, and each of which is adapted to preserve a different type of perishable foodstuff.

Moreover since the air outlet 17a of air-delivery duct 15 is dimensioned so that the ratio between the inner volume of storage compartment 12a and the overall cross sectional flow area of the same air outlet 17a is lower than the same ratio calculated for the each remaining storage compartment 12b, 12c, 12d of storage chamber 2 and is preferably furthermore lower than the first threshold value, i.e. lower than 0.02, the cooling system 3 is capable of keeping the inside of storage compartment 12a at a temperature lower than that of any one of the remaining storage compartments 12b, 12c, 12d, 12e, and 12f of storage chamber 2 (preferably ranging between -2°C and +3°C).

Furthermore, the particular shape of the various air outlets 17a, 17b, 17c, and 17d of a\ir-delivery duct 15 improves the distribution of the cold air inside each storage compartment 12a, 12b, 12c, 12d, 12e, 12f. Each air outlet 17a, 17b, 17c, 17d, in fact, produces a sort of horizontal air blade that extends deeply inside the corresponding storage compartment 12a, 12b, 12c, 12d, 12e, 12f.

In addition to the above, the control method implemented by control unit 21 allows a much more accurate control of the temperature of the air inside storage chamber 2, and a quicker return of the temperature of the air inside storage chamber 2 at the user-selected target temperature.

Clearly, changes may be made to the refrigerating appliance 1 without, however, departing from the scope of the present invention.

For example, one or more of the air outlets 17a, 17b, 17c, 17d of air-delivery duct 15 may consists of a small perforated area of the rear wall 20 of storage chamber 2. Preferably this small perforated area is furthermore located astride the midplane of the storage chamber 2.

Furthermore, one or more of the manually-removable horizontal partitioning shelves 13 may be replaced by a corresponding horizontal partitioning wall integrally formed with the inner shell 8 delimiting the storage chamber 2.