Control circuit for environments at different temperatures, in particular domestic refigerators

Abstract: The control circuit for environments at different temperatures, in particularly domestic refrigerators, is of the type comprising a freezer compartment (3) and a refrigeration compartment (4), an evaporator unit (5) positioned in said freezer compartment, a fan (6) associated with said evaporator unit, a compressor unit (7) operating said evaporator unit, a condenser (8), a delivery duct (10) from said fan for air taken from said evaporator unit in order to feed it into said refrigeration compartment, and a thermostat (12) disposed in said freezer compartment to control said fan and said compressor, and is essentially characterised by comprising in said refrigeration compartment a further thermostat (13) for controlling said fan (6) alone.

Description: This invention relates to a refrigerated environment, in particular a domestic refrigerator of the known no-frost type, of the type described in the preamble of the main claim. Such a refrigerated environment is known from GB-A-1 485 666. For simplicity and clarity, reference is made in the present context to a domestic refrigerator of the type comprising a single cabinet containing a freezer compartment and a refrigeration compartment, but the invention is equally applicable to any other type of refrigerated environment such as large industrial cold rooms comprising a freezer compartment and a refrigeration compartment for, in this latter case, preserving for example fresh meat. In the case considered herein, namely a domestic refrigerator of no-frost type, the refrigerated environment comprises a single fan associated with a single evaporator located in the freezer compartment and operated by a single compressor under the control of a single thermostat provided in the freezer compartment. In this type of refrigerator, the temperature in the refrigeration compartment is controlled on the basis of the temperature in the freezer compartment, this control being effected mainly by two methods which however are of complex implementation and rather high cost. One of these methods consists of providing in the duct which delivers air to the refrigeration compartment from the evaporator bank a further fan which operates intermittently under the control of a thermostat located in the refrigeration compartment (see, for instance, US-A-3 119 240). As stated, this method therefore has additional cost and maintenance. The other method consists of dividing the constant air delivery from the evaporator bank by a valve also associated with a thermostat located in the refrigeration compartment. An object of the present invention is to provide a refrigerated environment, in particular domestic refrigerators, which does not suffer from the drawbacks of conventional refrigerated environments or refrigerators. A further object of the invention is to provide a refrigerated environment of extremely simple conception and thus of high reliability. These objects are attained by the features of the characterizing part of the main claim. A preferred embodiment of the invention applied to a domestic refrigerator of the no-frost type is schematically illustrated by way of non-limiting example in the figures of the single accompanying drawing, in which: Figure 1 is a vertical section through the refrigerator, and Figure 2 is a section on the line II-II of Figure 1. With reference to said figures, the refrigerator, indicated overall by 1, comprises a first freezer compartment 3 and a second refrigeration compartment 4 in a single cabinet. In the freezer compartment 3 there is provided an evaporator unit 5 of the finned type associated with a fan 6. The refrigeration circuit also comprises a compressor 7 and condenser 8 with its own capillary tube (not shown). A suitably sized duct 10 is provided aligned with the fan 4 in correspondence with the separator baffle between the compartments 3 and 4 to deliver air taken from the evaporator 5 into said compartment 4. As can be seen in Figure 2, the air drawn in from the evaporator 5 is recirculated through the refrigeration compartment 4 and returned to the evaporator via slits 11. In a suitable position in the freezer compartment 3 there is located the sensitive part of a first thermostat 12 which based on its set temperature controls the operation of both the compressor 7 and fan 6. The aforesaid forms part of the known art. According to the invention, the temperature in the refrigeration compartment 4 is controlled by a second thermostat, the sensitive part 13 of which is advantageously located in the inner lower corner of said refrigeration compartment 4, said thermostat 13 being of fixed or adjustable setting. In operation, the first thermostat 12 measures the temperature in the freezer compartment 3 and based on this temperature either operates or halts the compressor 7 and fan 6. The temperature in the refrigeration compartment 4 depends on the quantity of cold air fed into said refrigeration compartment. It should be noted that the size of the duct 10 is calculated to always ensure in the refrigeration compartment 4 a suitably cold temperature of the order of between +3°C and +7°C, and advantageously +5°C. If the thermostat 13 detects too cold a temperature in the refrigeration compartment 4 (for example because the units 6 and 7 have remained operating for too long because new foods have been placed in the freezer compartment 3), said thermostat acts in the sense of interrupting the electrical circuit of the electrically driven fan 6 alone. When the temperature in the refrigeration compartment 4 again attains a predetermined value the thermostat 13 closes said electrical circuit. By halting the fan 6, the thermostat 13 inhibits any flow of cold air into the refrigeration compartment 4 and thus prevents its temperature becoming undesirably low even when the other thermostat 12 continues to require cold, thus operating the compressor 7 alone. It should be noted that, as the evaporator 5 is located in the freezer compartment 3,even when the fan 6 is at rest (but with the compressor 7 operating), a certain quantity of cold continues to be transferred from the evaporator 5 to the freezer compartment 3 because of the natural convention movement of the air. From the aforegoing it is apparent that the proposed method enables the temperature in the refrigeration compartment to be controlled in a rational manner without the use of special complex devices.

Claims: A refrigerated environment, particularly a domestic refrigerator of the no-frost type, comprising a freezer compartment (3), a refrigeration compartment (4), an evaporator unit (5) positioned in said freezer compartment, a thermostatically controlled single fan (6) associated with said evaporator unit, a thermostatically controlled compressor unit (7) operating said evaporator unit, the thermostatic control being entrusted to a thermostat (12) in the freezer compartment and a further thermostat (13) in the refrigeration compartment, a condenser (8), a duct (10) for delivering air from the freezer compartment (3) to the refrigeration compartment (4), the thermostat (13) in said refrigeration compartment (4) controlling only said single fan (6), characterized in that the thermostat (12) in the freezer compartment (3) controls both said single fan (6) and the compressor unit (7). A refrigerated environment is claimed in claim 1, characterized in that said further thermostat (13) is located in the coldest position in the refrigeration compartment (4), that is in a lower corner of said refrigeration compartment. A refrigerated environment as claimed in claim 2, characterized in that said further thermostat (13) is of fixed setting. A refrigerated environment as claimed in claim 2, characterized in that said further thermostat (13) is set to cut out at between +1°C and +3°C, and advantageously +2°C, and to cut in at between +3°C and +6C°, and advantageously +5°C. A refrigerated environment as claimed in claim 2, characterized in that said further thermostat (13) is of variable setting. A refrigerated environment as claimed in claim 1, characterized in that the duct (10) for delivering air from the freezer compartment (3) to the refrigeration compartment (4) is sized to always ensure in the refrigeration compartment (4) an adequately cold temperature of the order of between +3°C and +7°C, and advantageously +5°C. A refrigerated environment as claimed in claim 1, characterized in that the single fan (6) is located in the freezer compartment (3) in such a way as to cause circulation of air in both compartments (3, 4).

Inventors: CAVALLINI MARCO, CAVALLINI, MARCO
Applicants: OCEAN SPA, OCEAN S.P.A.
Application year: 1990
Main classification: F25D17
IPC codes: F25D17