REFRIGERATOR

Abstract

Refrigerator (1) comprising an outer casing (2) which has a thermal-insulating structure and is internally provided with a first (3) and a second (4) storage cavities that are thermal-insulated to one another and to the outside and each of which is adapted to accommodate perishable foodstuff; and an electrically-operated, cooling system (5) which is at least partially accommodated inside the outer casing (2) and is structured/adapted to cool down the inside of both said first (3) and said second (4) storage cavities; the first storage cavity (3) being additionally divided into a first (13) and a second (12) compartments that are both adapted to accommodate perishable foodstuff and directly communicate to one another; the cooling system (5) being adapted to circulate, in closed loop inside said first storage cavity (3), a flow of cold air (f) that crosses in sequence said first (13) and said second (12) compartment so as to cool down in sequence the same compartments (12, 13), and comprising an electrically-operated, heat-pump assembly (20) which is provided with a first evaporator (21) that cools down the first storage cavity (3), with a second evaporator (22) that cools down the second storage cavity (4), and with an electrically-operated flow di verier (44) which is located upstream of said first (21) and said second (22) evaporators and is adapted to selectively an alternatively channel the refrigerant towards the inlet of the first evaporator (21) or towards the inlet of the second evaporator (22).

Claims

1. Refrigerator (1) comprising an outer casing (2) which has a thermal-insulating structure and is internally provided with a first (3) and a second (4) storage cavities that are thermal-insulated to one another and to the outside and each of which is adapted to accommodate perishable foodstuff; and an electrically-operated, cooling system (5) which is at least partially accommodated inside the outer casing (2) and is structured/adapted to cool down the inside of both said first (3) and said second (4) storage cavities; the refrigerator (1) being characterized in that the first storage cavity (3) is additionally divided into a first (13) and a second (12) compartments that are both adapted to accommodate perishable foodstuff and directly communicate to one another; and in that the cooling system (5) is adapted to circulate, in closed loop inside said first storage cavity (3), a flow (f) of cold air that crosses in sequence said first (13) and said second (12) compartment so as to cool down in sequence the same compartments (12, 13), and additionally comprises an electrically-operated, heat-pump assembly (20) which is provided with a first evaporator (21) that cools down the first storage cavity (3), with a second evaporator (22) that cools down the second storage cavity (4), and with an electrically-operated flow diverter (44) which is located upstream of said first (21) and said second (22) evaporators and is adapted to selectively an alternatively channel the refrigerant towards the inlet of the first evaporator (21) or towards the inlet of the second evaporator (22).

2. Refrigerator according to claim 1, characterized in that said first compartment (13) is arranged underneath said second compartment (12).

3. Refrigerator according to claim 1, characterized in that said cooling system (5) additionally comprises: a first air-circulating duct (24) which extends behind a wall of said first storage cavity (3) and communicates with the first storage cavity (3) via a first (26) and a second (25) air-vent openings that are aligned, respectively, with the first compartment (13) and with the second compartment (12) of said first storage cavity (3); and a first electrically-operated air-circulating device (27) which is adapted to circulate the air in closed loop along said first air-circulating duct (24) and the adjacent first storage cavity (3); the first evaporator (21) of said heat-pump assembly (20) being located inside said first air-circulating duct (24) so as to cool down the air that flows along the first air-circulating duct (24).

4. Refrigerator according to claim 3, characterized in that said first electrically-operated air-circulating device (27) is located inside said first air-circulating duct (24), and/or in that said first (26) and said second (25) air-vent openings are located roughly at both ends of said first air-circulating duct (24).

5. Refrigerator according to claim 3, characterized in that the first evaporator (21) of said heat-pump assembly (20) is located inside the first air-circulating duct (24) immediately upstream of the first air-vent opening (26), so as to cool down the air that flows along the first air-circulating duct (24) immediately before said air passes into the first compartment (13) of said first storage cavity (3).

6. Refrigerator according to claim 3, characterized in that said first air-circulating duct (24) additionally has, upstream of the first air-vent opening (26), a third air-vent opening (70) that directly communicates with the second compartment (12) spaced apart from said second air-vent opening (25); said third air-vent opening (70) being dimensioned to allow a minority portion (f.sub.a) of the air that flows along the first air-circulating duct (24) to directly flow into the second compartment (12) bypassing the first compartment (13).

7. Refrigerator according to claim 3, characterized in that the first evaporator (21) of said heat-pump assembly (20) is accommodated inside the first air-circulating duct (24) so as to be crossed by the whole air flowing inside the first air-circulating duct (24).

8. Refrigerator according to claim 1, characterized in that the second evaporator (22) of said heat-pump assembly (20) is located directly inside the second storage cavity (4).

9. Refrigerator according to claim 1, characterized in that the cooling system (5) additionally comprises: a second air-circulating duct (30) which extends behind a wall of said second storage cavity (4) and communicates with the second storage cavity (4) via at least two air-vent openings (31, 32); and a second electrically-operated air-circulating device (33) which is adapted to circulate the air in closed loop along said second air-circulating duct (30) and the adjacent second storage cavity (4); the second evaporator (22) of said heat-pump assembly (20) being located inside said second air-circulating duct (30) so as to cool down the air that flows along the second air-circulating duct (30).

10. Refrigerator according to claim 9, characterized in that said second electrically-operated air-circulating device (33) is located inside said second air-circulating duct (30), and/or in that said two air-vent openings (31, 32) are located roughly at both ends of said second air-circulating duct (30).

11. Refrigerator according to claim 1, characterized in that said heat-pump assembly (20) additionally comprises, between the electrically-operated flow diverter (44) and each of said first (21) and second (22) evaporators, a respective refrigerant expansion device (45, 46) that causes the rapid expansion of the refrigerant directed towards the corresponding first (21) or second (22) evaporator.

12. Refrigerator according to claim 1, characterized in that said heat-pump assembly (20) additionally comprises an electrically-operated compressor (40) which is adapted to compress the gaseous-state refrigerant for supplying at its outlet/delivery a flow of high-temperature and high-pressure refrigerant; the outlets of said first (21) and said second (22) evaporators communicating with the inlet/suction of said compressor (40).

13. Refrigerator according to claim 12, characterized in that said heat-pump assembly (20) additionally comprises at least one refrigerant accumulator (48) which is interposed between the outlet of said first (21) and/or said second (22) evaporators and the inlet/suction of said compressor (40), and is adapted to accumulate the exceeding low-pressure refrigerant.

14. Refrigerator according to claim 1, characterized in that said heat-pump assembly (20) additionally comprises a backflow prevention device (47) which is located immediately downstream of the second evaporator (22) and is oriented so as to prevent the low-pressure refrigerant arriving from the outlet of the first evaporator (21) to flow towards the second evaporator (22).

15. Refrigerator according to claim 1, characterized in that the electrically-operated, cooling system (5) is adapted to keep the inside of the first compartment (13) of said first storage cavity (3) at a given first target temperature ranging between −8° C. and +5° C., and the inside of the second compartment (12) of said first storage cavity (3) at a given second target temperature ranging between +2° C. and +8° C.

Description

[0034] A non-limiting embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

[0035] FIG. 1 is a side view of a refrigerator realized in accordance with the teachings of the present invention, with parts in section and parts removed for clarity; whereas

[0036] FIG. 2 is a schematic view of the heat-pump assembly of the refrigerator shown in FIG. 1, with parts removed for clarity; whereas

[0037] FIG. 3 is a side view of the upper part of an alternative embodiment of refrigerator shown in FIG. 2, with parts in section and parts removed for clarity.

[0038] With reference to FIG. 1, reference number 1 denotes as a whole a refrigerator adapted for preserving perishable foodstuff and preferably suitable for domestic use, i.e. a household combo refrigerator.

[0039] Refrigerator 1 basically comprises: a preferably substantially parallelepiped-shaped, rigid outer casing 2 which is structured for stably resting on the floor/ground, has a thermal-insulating structure and is internally provided with at least two, preferably substantially vertically-aligned and preferably substantially parallelepiped-shaped, separate storage cavities 3 and 4 which are thermal-insulated to one another and to the outside, and each of which is adapted to accommodate perishable foodstuff; and an electrically-operated, cooling system 5 which is at least partially accommodated inside the outer casing 2, and is structured/adapted to cool down the inside of both storage cavities 3 and 4.

[0040] More in detail, the electrically-operated, cooling system 5 is structured to separately and independently cool down the storage cavities 3 and 4.

[0041] Preferably each storage cavity 3, 4 furthermore communicates with the outside through a respective large access opening which is preferably substantially rectangular in shaped and is preferably formed on the vertical front wall of the outer casing 2, and the refrigerator 1 preferably additionally comprises at least one sealing door which has a thermal-insulating structure and is adapted to close and substantially airtight seal the access opening of the storage cavities 3 and 4.

[0042] More in detail, with reference to FIG. 1, refrigerator 1 preferably comprises, for each storage cavity 3, 4, a respective sealing door 6, 7 which is preferably substantially rectangular in shape, has a thermal-insulating structure and is preferably flag hinged to the front of the outer casing 2 so as to be manually rotatable about a preferably substantially vertical-oriented, reference axis to and from a closing position (see FIG. 1) in which the same door 6, 7 rests/abuts on the front wall of the casing 2, so as to cover and substantially airtight seal the access opening of the corresponding storage cavity 3, 4.

[0043] In the example shown, in particular, the outer casing 2 preferably comprises: a substantially parallelepiped-shaped, self-supporting boxlike outer shell 8 which is preferably made of metal and/or plastic material; a pair of substantially basin-shaped, rigid inner shells 9 which are preferably made of plastic or metal material and are stably accommodated/recessed inside the outer shell 8, in an upright position and one spaced above the other, thus to form/delimit each a respective storage cavity 3, 4 of the refrigerator 1; and an intermediate thermal-insulating stuffing 10, which is preferably made of polymeric-material foam and is interposed between the inner shells 9 and the outer shell 8 so as to surround each inner shell 9 and minimize the heat exchange with the outside.

[0044] In addition to the above, with reference to FIG. 1, the first or upper storage cavity 3 of refrigerator 1 is vertically divided, preferably via a substantially horizontally-extending, unmovable internal partition septum 11, into an upper or conventional compartment 12 and a lower or zero-degree compartment 13 that are both adapted to accommodate perishable foodstuff and directly communicate to one another.

[0045] More in detail, the upper or conventional compartment 12 is preferably dimensioned to accommodate a relatively big amount of perishable foodstuff. The lower or zero-degree compartment 13, on the other hand, is preferably dimensioned to accommodate a relatively small amount of perishable foodstuff, and is preferably located adjacent to the bottom wall of storage cavity 3, where cold air usually accumulates.

[0046] The upper or conventional compartment 12 and the lower or zero-degree compartment 13, therefore, are complementary to one another and share the same access opening, i.e. the large access opening closed by the sealing door 6.

[0047] The cooling system 5, in turn, is adapted to cool down the storage cavity 3 so as to keep the inside of the zero-degree compartment 13 at a given first target temperature preferably suitable for short-term preservation of perishable foodstuff, and to keep the inside of the conventional compartment 12 at a given second target temperature slightly greater than the first target temperature and again preferably suitable for short-term preservation of perishable foodstuff.

[0048] More specifically, with reference to FIG. 1, the cooling system 5 of refrigerator 1 is adapted to circulate, in closed loop inside the storage cavity 3, a flow f of cold air that crosses in short sequence the zero-degree compartment 13 and the conventional compartment 12 of storage cavity 3, so as to cool down in sequence the zero-degree compartment 13 and the conventional compartment 12.

[0049] Since the flow f of cold air crosses in sequence the compartments 13 and 12, the inside of the zero-degree compartment 13 is kept at a temperature slightly lower than the inside of the conventional compartment 12.

[0050] More specifically, the first target temperature preferably ranges between −8° C. and +5° C., and the second target temperature preferably ranges between +2° C. and +8° C.

[0051] With reference to FIG. 1, moreover the cooling system 5 is preferably additionally adapted to cool down the inside of the second or lower storage cavity 4 so as to keep the inside of storage cavity 4 at a given third target temperature which is preferably lower than said first and/or second target temperature/s and is preferably also suitable for freezing perishable foodstuff, i.e. for long-term preservation of perishable foodstuff. Preferably said third target temperature furthermore ranges between −30° C. and −10° C.

[0052] More in detail, the cooling system 5 of refrigerator 1 is preferably additionally adapted to separately circulate a second flow of cold air in closed loop inside the storage cavity 4, so as to cool down the whole volume of storage cavity 4.

[0053] Preferably the refrigerator 1 additionally comprises: at least one and preferably a number/plurality of first boxlike drawer containers 14 which are fitted in manually extractable manner into the zero-degree compartment 13, preferably one vertically-stacked to the other, and are each adapted to accommodate vegetables and similar perishable foodstuff; and optionally also one or more horizontally-extending and preferably manually removable, partitioning shelves 15 which are adapted to support perishable foodstuff, and are arranged inside the conventional compartment 12 of storage cavity 3 vertically spaced to one another.

[0054] All partitioning shelves 15 are therefore located above the zero-degree compartment 13, or rather above the partition septum 11.

[0055] The/each drawer container 14 is preferably made of plastic material, whereas each partitioning shelve 15 is preferably made of glass.

[0056] In addition to the above, the refrigerator 1 preferably moreover comprises at least one and preferably a number/plurality of second boxlike drawer containers 16 which are fitted in manually extractable manner into the lower storage cavity 4, preferably vertically-stacked to one another, and are each adapted to accommodate frozen perishable foodstuff. Moreover, likewise the drawer containers 14, the drawer containers 16 are preferably made of plastic material.

[0057] With reference to FIGS. 1 and 2, in turn, the cooling system 5 of refrigerator 1 comprises an electrically-operated, heat-pump assembly 20 provided with two evaporators distinct/discrete to one another. The first evaporator 21 is adapted to cool down solely the air circulating inside the storage cavity 3. The second evaporator 22, instead, is preferably adapted to cool down solely the air circulating inside the storage cavity 4.

[0058] More in detail, the cooling system 5 comprises: a first air-circulating duct 24 that extends behind the rear wall or a lateral wall of the first or upper storage cavity 3, preferably substantially vertically and preferably substantially for the whole height of storage cavity 3, and communicates with the adjacent storage cavity 3 solely via two vertically-spaced main air-vent openings 25 and 26 which are located roughly at both ends of the same air-circulating duct 24 and are aligned one with the zero-degree compartment 13 and the other with the conventional compartment 12; and an electric fan 27 or other electrically-operated air-circulating device, which is adapted to circulate the air in closed loop along the air-circulating duct 24 and the adjacent storage cavity 3 and is preferably located inside the air-circulating duct 24.

[0059] The evaporator 21 of heat-pump assembly 20 is located inside the air-circulating duct 24 so as to cool down the air that flows along the air-circulating duct 24 directed back into storage cavity 3. Preferably the evaporator 21 is furthermore located inside the air-circulating duct 24 downstream of the electric fan 27.

[0060] The electric fan 27 of cooling system 5, in turn, is oriented so as to circulate, in closed loop along the air-circulating duct 24 and the adjacent storage cavity 3, a flow f of cold air that firstly cools down the inside of the zero-degree compartment 13 and subsequently cools down the inside of the conventional compartment 12 before returning back into the air-circulating duct 24 that accommodates the evaporator 21.

[0061] More in detail, with reference to FIG. 1, the upper air-vent opening 25 of air-circulating duct 24 is preferably directly faced/aligned to the upper or conventional compartment 12 preferably close to the ceiling of storage cavity 3, whereas the lower air-vent opening 26 of air-circulating duct 24 is preferably directly faced/aligned to the zero-degree compartment 13 preferably close to the bottom of storage cavity 3.

[0062] Electric fan 27, in turn, is preferably located inside the air-circulating duct 24, preferably immediately downstream of the upper air-vent opening 25, and is preferably oriented so as to push/move the air downwards along the air-circulating duct 24, towards the lower air-vent opening 26.

[0063] The air contained into storage cavity 3 therefore enters into the air-circulating duct 24 via the upper air-vent opening 25, flows downwards inside the air-circulating duct 24 glazing the evaporator 21, and comes out of the air-circulating duct 24 via the lower air-vent opening 26.

[0064] After having cooled down the zero-degree compartment 13, the flow f of cold air coming out of air-vent opening 26 then move upwards inside the storage cavity 3 towards the conventional compartment 12 preferably skimming the inner face of sealing door 6.

[0065] In other words, the cooling system 5 of refrigerator 1 cools down the air directed towards the zero-degree compartment 13, whereas the upper or conventional compartment 12 receives the cold air from the the zero-degree compartment 13.

[0066] With reference to FIG. 1, in the example shown in particular the evaporator 21 is preferably located inside the air-circulating duct 24 immediately upstream of the lower air-vent opening 26, so as to cool down the air that flows downwards along the air-circulating duct 24 immediately before said air passes into the zero-degree compartment 13. Preferably the evaporator 21 is furthermore accommodated inside the air-circulating duct 24 so as to crossed by the whole air flowing inside the air-circulating duct 24.

[0067] With reference to FIG. 1, the cooling system 5 preferably additionally comprises: a second air-circulating duct 30 which extends behind the rear wall or a lateral wall of the second or lower storage cavity 4, preferably substantially vertically and preferably substantially for the whole height of storage cavity 4, and which communicates with the adjacent storage cavity 4 via at least two vertically-spaced air-vent openings 31 and 32, preferably located at both ends of the air-circulating duct 30; and an electric fan 33 or other electrically-operated air-circulating device, which is located inside the air-circulating duct 30 and is adapted to circulate the air in closed loop along the air-circulating duct 30 and the adjacent storage cavity 4.

[0068] The evaporator 22 of heat-pump assembly 20 is preferably located inside the air-circulating duct 30 so as to be able to cool down the air that flows along the air-circulating duct 30 directed back to the storage cavity 4.

[0069] More in detail, in the example shown the air-circulating duct 30 preferably communicates with the adjacent second or lower storage cavity 4 solely via an upper and a lower air-vent openings. The upper air-vent opening 31 is preferably located close to the ceiling of storage cavity 4. The lower air-vent opening 32, in turn, is preferably located close to the bottom of storage cavity 4.

[0070] With reference to FIG. 1, the electric fan 33 is preferably located inside the air-circulating duct 30 immediately downstream of the upper air-vent opening 31, and is preferably oriented so as to push/move the air upwards along the air-circulating duct 30. The air contained into storage cavity 4 therefore enters into the air-circulating duct 30 via the lower air-vent opening 32 and flows upwards inside the air-circulating duct 30, up to the upper air-vent opening 31.

[0071] The evaporator 22, in turn, is preferably located inside the air-circulating duct 30 approximately at half height of the air-circulating duct 30, i.e. between the air-vent openings 31 and 32, and is preferably accommodated into air-circulating duct 30 so as to be crossed by the whole air flowing along the air-circulating duct 30.

[0072] With reference to FIGS. 1 and 2, the heat-pump assembly 20 of cooling system 5, on the other hand, is structured to operate the first and second evaporators 21 and 22 alternatively to one another. In other words, the first and second evaporators 21 and 22 of heat-pump assembly 20 receive the low-pressure refrigerant selectively and alternatively to one another.

[0073] More in detail, the heat-pump assembly 20 of cooling system 5 includes an electrically-operated flow diverter which is located upstream of evaporators 21 and 22 and is adapted to selectively an alternatively channel the refrigerant towards the inlet of evaporator 21 or towards the inlet of evaporator 22.

[0074] In the example shown, in particular, the heat-pump assembly 20 preferably comprises: an electrically-operated compressor 40 which is preferably housed into a specific compressor compartment preferably formed on the back of the outer casing 2, and is adapted to compress a low-temperature and low-pressure gaseous-state to refrigerant for supplying at outlet/delivery a flow of high-temperature and high-pressure refrigerant; and a first heat-exchanger 41 that receives the high-temperature and high-pressure gaseous-state refrigerant from compressor 40, is preferably located on the rear wall of outer casing 2, i.e. opposite to the large access openings of storage cavities 3 and 4, and is structured to allow the high-temperature and high-pressure refrigerant arriving from compressor 40 to release heat to the outside environment, thus reducing its temperature.

[0075] Additionally the heat-pump assembly 20 preferably comprises: a second heat-exchanger 42 that receives the low-pressure and low-temperature refrigerant, and is structured to allow the low-pressure and low-temperature refrigerant to absorb heat from the outside while flowing through the same heat-exchanger 42; and a third heat-exchanger 43 that receives the low-pressure and low-temperature refrigerant, and is structured to allow the low-pressure and low-temperature refrigerant to absorb heat from the outside while flowing through the same heat-exchanger 43.

[0076] Furthermore heat-exchanger 42 is preferably located inside the air-circulating duct 24 and is preferably able to cool down the whole air flowing inside the air-circulating duct 24. Heat-exchanger 43, in turn, is preferably located inside the air-circulating duct 30 and is preferably able to cool down the whole air flowing inside the air-circulating duct 30.

[0077] Preferably second and/or third heat-exchanger/s 42 and/or 43 is/are finned pack heat-exchanger/s.

[0078] With reference to FIG. 2, preferably the heat-pump assembly 20 additionally comprises an electrically-operated flow diverter 44 which is located between the heat-exchanger 41 and the heat-exchangers 42 and 43, and is adapted to selectively an alternatively channel, on command, the high-pressure refrigerant arriving from the heat-exchanger 41 towards the inlet of heat-exchanger 42 or towards the inlet of heat-exchanger 43.

[0079] More in detail, the electrically-operated flow diverter 44 preferably has one inlet and two outlets and is structured to selectively and alternatively put its inlet in direct communication with any one of its two outlets. In other words the flow diverter to 44 is preferably an electrically-operated three-way valve.

[0080] Preferably the heat-pump assembly 20 furthermore comprises: a first capillary tube 45 which is located between the flow diverter 44 and the heat-exchanger 42 and is structured to cause the rapid expansion of the high-pressure refrigerant arriving from heat-exchanger 41, so as to rapidly highly reduce both temperature and pressure of the refrigerant directed towards the heat-exchanger 42; and a second capillary tube 45 which is located between the flow diverter 44 and the heat-exchanger 43 and is structured to cause the rapid expansion of the high-pressure refrigerant arriving from heat-exchanger 41, so as to rapidly highly reduce both temperature and pressure of the refrigerant directed towards the heat-exchanger 43.

[0081] The inlet of flow diverter 44 directly communicates with the heat-exchanger 41 so as to receive the high-pressure refrigerant coming out from the heat-exchanger 41. A first outlet of flow diverter 44 directly communicates with capillary tube 45 and a second outlet of flow diverter 44 directly communicates with capillary tube 46.

[0082] Obviously any one of the capillary tubes 45 and 46 may be replaced by an expansion valve/s or other refrigerant expansion device which is structured to cause the rapid expansion of the refrigerant flowing through the same refrigerant expansion device.

[0083] The inlet/suction of compressor 40, in turn, communicates with the outlet of both heat-exchangers 42 and 43 so as to receive the low-pressure refrigerant coming out from any one of the same heat-exchangers 42 and 43.

[0084] The heat-exchanger 41 is therefore the condenser of heat-pump assembly 20. The heat-exchanger 42 is the first evaporator 21 of heat-pump assembly 20 and is preferably therefore located inside the air-circulating duct 24, preferably immediately upstream of the lower air-vent opening 26. The heat-exchanger 43, in turn, is the second evaporator 22 of heat-pump assembly 20 and is preferably therefore located inside the air-circulating duct 30.

[0085] With reference to FIG. 2, preferably the heat-pump assembly 20 additionally includes a one-way valve 47 or other backflow prevention device, which is located immediately downstream of heat-exchanger 43, i.e. the second evaporator 22 of heat-pump assembly 20, and is oriented so as to prevent the low-pressure refrigerant arriving from the outlet of heat-exchanger 42, i.e. the first evaporator 21 of heat-pump assembly 20, to flow towards the outlet of heat-exchanger 43.

[0086] Preferably, the heat-pump assembly 20 moreover comprises a refrigerant accumulator 48 and optionally also a refrigerant filter and/or dryer 49.

[0087] The refrigerant accumulator 48 is preferably located immediately upstream of the suction/inlet of compressor 40, i.e. between the inlet/suction of compressor 40 and the outlets of both first and second evaporators 21 and 22 of heat-pump assembly 20, and is adapted to accumulate the exceeding low-pressure refrigerant when the flow diverter 44 channels the refrigerant to evaporator 21 of heat-pump assembly 20.

[0088] Preferably the refrigerant accumulator 48 is furthermore adapted to block hold and accumulate the liquid-state refrigerant eventually flowing towards the inlet/suction of compressor 40.

[0089] More in detail, the refrigerant accumulator 48 preferably basically consists in an airtight tank dimensioned to accumulate the exceeding low-pressure refrigerant when the flow diverter 44 channels the refrigerant towards the evaporator 21 of heat-pump assembly 20.

[0090] Clearly the one-way valve 47, if present, is preferably interposed between the outlet of heat-exchanger 43 and the refrigerant accumulator 48.

[0091] The refrigerant filter and/or dryer 49, in turn, is preferably interposed between the heat-exchanger 41, i.e. the condenser of heat-pump assembly 20, and the flow diverter 44, and is adapted to adsorb system contaminants (such as water) that can create acids, and to trap any solid particles in the refrigerant.

[0092] With reference to FIG. 1, the cooling system 5 finally includes an electronic control unit 50 which is preferably recessed into a corresponding seat formed inside the outer casing 2, and is adapted to selectively and alternatively activate the electric fans 27 and 33 in combination with the heat-pump assembly 20, so as to keep the temperature inside the zero-degree compartment 13 of storage cavity 3 and the temperature inside the whole storage cavity 4 at corresponding target temperatures.

[0093] More in detail, the control unit 50 preferably electronically communicates with one or more temperature sensors (not shown in the figures) preferably located inside the zero-degree compartment 13 of storage cavity 3 and/or inside the conventional compartment 12 of storage cavity 3 and/or inside the storage cavity 4, and is adapted to selectively and alternatively activate the electric fans 27 and 33 in combination with the flow diverter 44 and the compressor 40 of heat-pump assembly 20 on the basis of the signals arriving from the aforesaid temperature sensors.

[0094] More specifically, when the zero-degree compartment 13 and/or the conventional compartment 12 of storage cavity 3 need to be cooled, the electronic control unit 50 drives the flow diverter 44 so as to put the outlet of heat-exchanger 41 in direct communication with the capillary tube 45, and then activates the compressor 40 and the electric fan 27 so as to circulate a flow of cold air in closed loop inside the storage cavity 3 and the adjacent air-circulating duct 24.

[0095] Instead, when the storage cavity 4 need to be cooled, the electronic control unit 50 drives the flow diverter 44 so as to put the outlet of heat-exchanger 41 in direct communication with the capillary tube 46, and then activates the compressor 40 and the electric fan 33 so as to circulate a flow of cold air in closed loop inside the storage cavity 4 and the adjacent air-circulating duct 30.

[0096] Preferably the electronic control unit 50 is additionally capable of varying the speed and/or capacity of compressor 40 so as to timely vary, according to the evaporator 21, 22 in use at the moment, the flowrate of the refrigerant circulating inside the heat-pump assembly 20.

[0097] General operation of the refrigerator 1 is easily inferable from the above description and therefore requires no further explanations.

[0098] The advantages resulting from the particular structure of the cooling system 5 of refrigerator 1 are large in number.

[0099] Cooling down in sequence both the zero-degree compartment 13 and the conventional compartment 12 of storage cavity 3 with the same flow of cold air allows to simplify the structure of cooling system 5, without however jeopardizing the temperature stability inside both the upper and the lower storage cavities 3 and 4.

[0100] Furthermore the use of two alternatively-operated evaporators 21 and 22 allows to significantly improve the overall efficiency of heat-pump assembly 20.

[0101] To operate correctly, the second evaporator 22 of heat-pump assembly 20 in fact requires a low-pressure refrigerant with a temperature significantly lower than that required by the first evaporator 21. Therefore operating the evaporators 21 and 22 alternatively to one another allows to supply each evaporator 21, 22 of heat-pump assembly 20 with the low-pressure and low-temperature refrigerant having the most appropriate temperature and pressure values, thus significantly increasing the heat exchange with the corresponding storage cavity 3, 4.

[0102] Clearly, changes may be made to the refrigerator 1 without, however, departing from the scope of the present invention.

[0103] For example, the zero-degree compartment 13 could be arranged above the conventional compartment 12 of storage cavity 3.

[0104] According to a less-sophisticated first alternative embodiment, moreover the heat-pump assembly 20 may comprise, in place of the two capillary tubes or other refrigerant expansion devices 45 and 46, a single capillary tube or other refrigerant expansion device which is located between the outlet of heat-exchanger 41, i.e. the condenser of heat-pump assembly 20, and the inlet of flow diverter 44.

[0105] According to a second non-shown alternative embodiment, furthermore, the heat-pump assembly 20 may comprise two discrete refrigerant accumulators located one immediately downstream of evaporator 21 and the other immediately downstream of evaporator 22. Alternatively, the heat-pump assembly 20 may comprise a single refrigerant accumulator located immediately downstream of either the evaporator 21 or the evaporator 22.

[0106] In addition to the above, according to a further non-shown alternative embodiment, rather than being a finned pack heat-exchanger, the heat-exchanger 42 forming the evaporator 21 may comprise: a metal plate which is preferably made of aluminum and is located or incorporated into the air-circulating duct 24 preferably so as to form a part of the rear sidewall of the air-circulating duct 24; and a flat coil tube that rests on one of the two faces of the metal plate so as to exchange heat with the same plate, and is crossed by the low-temperature and low-pressure refrigerant arriving from the capillary tube 45 or other refrigerant expansion device.

[0107] According to a further non-shown alternative embodiment, the cooling system 5 preferably lacks the air-circulating duct 30 and the electric fan 33, and the heat-exchanger 43 forming the evaporator 22, rather than being a finned pack heat-exchanger located inside the air-circulating duct 30, is located directly inside the second or lower storage cavity 4, and preferably basically consists in a flat coil tube which is preferably arranged adjacent to the rear sidewall and/or to a lateral sidewall of the second or lower storage cavity 4 so as to exchange heat directly with the inside of storage cavity 4, and is crossed by the low-temperature and low-pressure refrigerant arriving from the capillary tube 46 or other refrigerant expansion device.

[0108] Finally, with reference to the alternative embodiment shown in FIG. 3, a minority portion f.sub.a of the flow f of cold air flowing downwards along the air-circulating duct 24 is preferably directly channeled into the conventional compartment 12, bypassing the zero-degree compartment 13.

[0109] More specifically, the air-circulating duct 24 of cooling system 5 preferably has, upstream of the air-vent opening 26 and preferably downstream of evaporator 21, a small auxiliary air-vent opening 70 that directly communicates with the conventional compartment 12 spaced apart from the air-vent opening 25, and has a clear section specifically dimensioned to allow a predetermined small amount of the airflow flowing downwards into the air-circulating duct 24 to freely pass/move into the conventional compartment 12 before arriving at air-vent opening 26.

[0110] In this alternative embodiment, therefore, the evaporator 21 is preferably no more located immediately upstream of the lower air-vent opening 26.

[0111] In the example shown, in particular, the clear section of the auxiliary air-vent opening 70 is preferably dimensioned to allow the early outflow into the conventional compartment 12 of a given percentage of the airflow preferably lower than 15%.

[0112] In other words, at auxiliary air-vent opening 70, the flow f of cold air flowing downwards along the air-circulating duct 24 splits into two branches f.sub.a and f.sub.b directed one straight towards the conventional compartment 12 and the other straight towards the zero-degree compartment 13.

[0113] The flowrate of branch f.sub.a is preferably less than or equal to 15% of the flow f of cold air flowing downwards along the air-circulating duct 24, whereas the flowrate of branch f.sub.b is preferably greater than or equal to 85% of the flow f of cold air flowing downwards along the air-circulating duct 24.

[0114] In this alternative embodiment, therefore, solely the branch f.sub.b of flow f crosses in short sequence the zero-degree compartment 13 and the conventional compartment 12 of storage cavity 3, so as to cool down in sequence the zero-degree compartment 13 and the conventional compartment 12.