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

[0001] This industrial invention patent relates to a control circuit for environments at different temperatures, in particular domestic refrigerators.

[0002] 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.

[0003] In the case considered herein, namely a domestic refrigerator, the no-frost type will be considered at this 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.

[0004] 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.

[0005] 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. As stated, this method therefore additional cost and maintenance.

[0006] 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.

[0007] An object of the present invention is to provide a control circuit for environments at different temperatures, in particular domestic refrigerators, which does not suffer from the drawbacks of conventional circuits.

[0008] A further object of the invention is to provide a control circuit of extremely simple conception and thus of high reliability. These and further objects will be apparent to the expert of the art from the following description.

[0009] The control circuit for environments at different temperatures, in particular domestic refrigerators, is of the type comprising a freezer compartment and a refrigeration compartment, an evaporator unit positioned in said freezer compartment, a fan associated with said evaporator unit, a compressor unit operating said evaporator unit, a condenser, a delivery duct from said fan for air taken from said evaporator unit in order to feed it into said refrigeration compartment, and a thermostat 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 for controlling said fan alone. 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.

[0010] 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.

[0011] 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).

[0012] 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.

[0013] 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.

[0014] 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.

[0015] The aforesaid forms part of the known art.

[0016] 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 and/or adjustable setting.

[0017] 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.

[0018] 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.

[0019] 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 interupting 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.

[0020] 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.

[0021] 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.

[0022] 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

1. A control circuit for environments at different temperatures, in particularly domestic refrigerators, 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, characterised by comprising in said refrigeration compartment (4) a further thermostat (13) for controlling said fan (6) alone.

2. A control circuit as claimed in claim 1, characterised in that said further thermostat (13) is located in the coldest position in the refrigeration compartment.

3. A control circuit as claimed in claim 2, characterised in that said further thermostat is of fixed setting.

4. A control circuit as claimed in claim 2, characterised in that said further thermostat 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 +6°C, and advantageously +5°C.

5. A control circuit as claimed in claim 2, characterised in that said further thermostat is of variable setting.

6. A control circuit as claimed in claim 1, characterised in that said delivery duct (10) is sized to always ensure in the refrigeration compartment 4 and adequately cold temperature of the order of between +3°C and +7°C, and advantageously +5°C. All as described, illustrated, claimed and for the objects specified.

Drawing