GB1591693A

GB1591693A - Refrigerator-freezer

Info

Publication number: GB1591693A
Application number: GB1059/78A
Authority: GB
Original assignee: Philips Gloeilampenfabrieken NV
Current assignee: Koninklijke Philips NV
Priority date: 1977-01-14
Filing date: 1978-01-11
Publication date: 1981-06-24
Also published as: DE7800183U1; DE2800285A1; FR2377591A1; IT1192166B; FR2377591B1; SE7800278L

Description

(54) REFRIGERATOR-FREEZER (71) We, N.V. PHILIPS GLOEILAMPEN FABRIEKEN, a limited liability Company, organised and established under the laws of the Kingdom of the Netherlands, of Emmasingel 29, Eindhoven, the Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a refrigerator.

freezer having a first compartment arranged for operation at a refrigeration temperature and a second compartment arranged for operation at a lower freezer temperature and having a refrigeration fluid flow circuit comprising a compressor, a condenser, a first evaporation section associated with the first compartment, a second evaporation section associated with the second compartment, a solenoid valve, and a first and second capillary tube.

A refrigerator-freezer of this type in which usually the first compartment (the refrigeration compartment) operates at a temperature not less than 0 C and the second compartment (the freeze compartment) operates at a temperature not greater than -18"C is known in which in its refrigeration fluid flow circuit the two capillary tubes are connected in series upstream of the first evaporation section. The said solenoid valve is located in a bypass bridging the second capillary tube and first evaporation section. In operation, the solenoid valve is de-energized and thus closed when both the refrigeration and freezer compartments are to be cooled.In this case the refrigeration fluid is firstly throttled by the two capillary tubes and then progressively evaporates on passing into the two evaporation sections to finally flow through a, filter into the compressor and then into. the condenser. When only the freezer compartment is to be cooled, the solenoid valve is energized so that only the second evaporation section operates. This known refrigerator-freezer has certain disadvantages. Firstly, as the solenoid valve is located downstream of the first capillary tube, it operates under poor hydrodynamic conditions as in fact the refrigeration fluid passes through it in a mixed liquid-vapour phase. Secondly, the solenoid valve operates at a rather low temperature (of the order of - 100C) because of which it must be of special construction and it is consequently costly to manufacture.The solenoid valve must therefore be kept thermally insulated and it is, in practice, accommodated in one of the thermal insulation walls of the refrigerator-freezer. Consequently access to the solenoid valve becomes difficult, and thus any repair or replacement of the solenoid valve is unnecessarily complicated and likely to be correspondingly costly.

Finally, this known refrigerator-freezer has a high electricity consumption when only the freezer compartment is required to be cooled over a long period of time. In practice this happens for example during holiday periods when only frozen foods are expected to be preserved. Under these circumstances the solenoid valve has to be kept energized for the whole period for example even for a duration of several weeks of continuous operation.

One object of the present invention is to provide a refrigerator-freezer having a refrigeration fluid flow circuit, certain components of which are able to operate under reduced loading conditions, as compared with the conventional circuit and which components can therefore be of a simple and low cost construction.

A further object is to provide a refrigerator-freezer the operation of which is economical and which enables certain maintenance problems of the solenoid valve to be reduced.

According to the invention, there is provided a refrigerator-freezer having a, first compartment arranged for operation at a refrigeration temperature and a second compartment arranged for operation at a lower freezer temperature and having a refrigeration fluid flow circuit comprising a compressor, a condenser, a first evaporation section associated with the first compartment, a second evaporation section associated with the second compartment, a solenoid valve, and a first and a second capillary tube, wherein the two capillary tubes are connected in parallel and the solenoid valve is located upstream of only one of the capillary tubes.

One advantage of the invention is that the refrigeration fluid flows through the solenoid valve only in the liquid phase, so that the solenoid valve is able to operate at optimum hydrodynamic conditions.

In a preferred embodiment of the invention, the solenoid valve is located upstream of the said capillary tube, which opens into the first evaporation section.

A further advantage of the invention is that the solenoid valve is energized for fairly short periods, that is when it is required to cool the refrigeration compartment. Consequently, the contribution made by the solenoid valve to the total annual electricity consumption of the refrigerator-freezer is small.

By way of example, particular embodiments of the invention will be described with reference to the accompanying drawings in which: Figure 1 is a view partly in section of a refrigerator-freezer in accordance with the present invention, Figure 2 is a diagrammatic view of a first embodiment of a refrigeration fluid flow circuit for the refrigerator-freezer of Figure 1, Figure 3 is a diagrammatic view of a second embodiment, Figure 4 is a first electrical circuit diagram for the refrigerator-freezer of Figure 1 and, Figure 5 is a second electrical circuit diagram for this latter.

Figure 1 shows a refrigerator-freezer comprising an upper refrigeration compartment 1 for preserving fresh foods (at an operating temperature not less than O"C) and a lower freezer compartment 2 for freezing fresh foods and for preserving already frozen foods (at an operating temperature normally not exceeding - 180C). Each compartment is closed by its own door (not shown) and is thermally insulated from the other compartment. The refrigerator-freezer is equipped with a refrigeration fluid flow circuit comprising a compressor CM, a condenser CD, a first evaporation section El for the refrigeration compartment 1, a second evaporation section E2 for the freezer compartment 2, a drier filter SF, a solenoid valve SV, a first capillary tube C1 and a second capillary tube C2.Preferably, both the capillary tubes have the same throughput of refrigeration fluid at the pressure conditions present, for example 4.5 litres per minute. For reasons which will be explained in further detail later, the solenoid valve SV is housed in the same rear space 3 of the refrigerator-freezer as that which houses the compressor CM. The refrigeratorfreezer is also provided with a first thermal stat T1 for the refrigeration compartment 1 and a second thermostat T2 for the freezer compartment 2, and (according to the embodiment of the circuit diagram shown in Figure 4) is can also comprise an electrical resistance heater 15 for defrosting the first evaporation section El.

As can be seen, the different components of the refrigeration fluid flow circuit have the same reference letters and numerals in Figures 1, 2 and 3.

In the first embodiment of the refrigeration fluid flow circuit ((Figure 2), the second capillary tube C2 is arranged in parallel with the first capillary tube C1 and the first evaporation section El, being located between the junction P1 (immediately downstream of the condenser CD) and junction P2 (between the two evaporation sections El and E2 which are connected in series).

The solenoid valve is positioned beyond the junction P1 and is located immediately upstream of only the first capillary tube Cl, which opens into the first evaporation section El.

The electrical circuits as shown in the diagrams of Figures 4 and 5 are suitable for operating either embodiment of the refrigeration fluid flow circuits.

The circuit diagram of Figure 4 comprises the line conductors 7 and 8 at electricity supply mains voltage (for example 220 V, 50 Hz) with two parallel switches 9 and 10, actuated by the first thermostat T1 for the refrigeration compartment 1 and the second thermostat T2 for the freezer compartment 2. The first switch 9 may be changed over from a first position in which it is closed across the contacts 11 and 12, to a second position in which it is closed across contacts 11 and 13. A solenoid 14 of the solenoid valve SV is connected between the contact 12 and the line conductor 8. An electrical resistance heater 15 for defrosting the first evaporation section El and/or refrigeration compartment 1 is connected between the contact 13 and the said conductor 8. The second switch 10 may either close across the contacts 16 and 17 or be open, according to the state of the thermostat T2. In the closed position, the second switch 10 allows energisation of a motor 18 of the refrigerator compressor CM.

The circuit diagram of Figure 5 relates to a refrigerator in which the defrosting of the evaporation section takes place without the aid of a special electrical resistance heater, by virtue of a suitable arrangement of the characteristics of the refrigeration fluid flow circuit and the degree of thermal insulation of the walls of the refrigeratorfreezer itself. This diagram shows the line conductors 20 and 21 at mains voltage with two parallel switches 22 and 23 actuated respectively by the first thermostat T 1 for the refrigeration compartment 1 and the second thermostat T2 for the freezer a;om- partment 2. The switch 22 may be closed across the contacts 24 and 25, or opened according to the state of the thermostat T2.

In the closed position it allows energisation of the solenoid 26 of the solenoid valve SV.

The switch 23 may switch between a first position in which it is closed across the contacts 27 and 28, and a second position in which it is closed across the contacts 27 and 29. A motor 30 of the compressor CM is connected between the contact 28 and line conductor 21, and a conductor 31 leads from the contact 29 to terminate in an auxiliary contact 32, positioned between the contact 25 and solenoid 26 of the solenoid valve SV.

Consideration will first be given to the operation of a refrigerator-freezer in accordance with Figure 1, being provided with the refrigeration fluid flow circuit of Figure 2 and with the electrical circuit of Figure 4.

It must however be emphasised that the refrigerator-freezer may alternatively have the electrical circuit of Figure 5.

When both compartments 1 and 2 are to be cooled, the thermostat T1 keep the switch 9 closed across the contacts 11 and 12, while the thermostat T2 keeps the switch 10 closed. Consequently, the motor 18 of the compressor CM operates, and the solenoid valve SV is open as its solenoid 14 is energised. In the refrigeration fluid flow circuit, the fluid arrives entirely in the liquid phase from the condenser CD at the junction P1. As the capillary tubes C1 and C2 have the same throughput, a first half volume of said fluid enters the solenoid valve SV and then flows into the first capillary tube C1, into the first evaporation section El and then it arrives in vapour phase at the junction P2.A second half volume of the refrigeration fluid flows from the junction P1 through the second capillary tube C2 to arrive at the junction P2 in a mixed liquid-vapour phase. The total volume of the refrigeration fluid then passes into the evaporation section E2 where it completes its evaporation and then continues its flow through the further components of the refrigeration fluid flow circuit to junction P1. When the first thermostat T1 detects a temperature corresponding to its break temperature, corresponding in the refrigeration compartment 1 to an operating temperature of not less than 0 C, it actuates the switch 9 to close the contacts 11 and 13.

Usually the second thermostat T2 has not yet reached its break temperature, and the switch 10 remains closed, Consequently, the motor 18 of the compressor CM continues to operate, while the solenoid valve SV closes because its solenoid 14 is de-energised and the resistance heater 15 is energised. In the refrigeration fluid flow circuit, the fluid at junction P1 finds the solenoid valve SV closed, and the fluid then enters the second capillary tube C2, and the second evaporation section E2. In the meantime, the first evaporation section El is defrosted by the resistance heater 15.When the second thermostat T2 detects its break temperature, corresponding in the freezer compartment 2 to an operating temperature not exceeding - 180C, it opens the switch 10, so de-energizing the motor of the compressor CM and terminating the forced circulation of fluid in the refrigeration fluid flow circuit of Figure 2. During this period, the first evaporation section El continues to be defrosted until a thermostat, usually firstly the thermostat T1, detects its make temperature, corresponding to the end of said defrosting period. Consequently the solenoid valve SV is again open when, a few minutes later, the thermostat T2 also detects its make temperature and the closure of thermostat T2 causes the motor 18 of the compressor CM to return to operation.The purpose of this early opening of the solenoid valve SV is to balance the pressures in the refrigeration fluid flow circuit, and hence facilitate the start of the compressor. A new cycle similar to that already described thus begins with the further operation of the compressor CM.

In the second embodiment of the refrigeration fluid flow circuit (Figure 3), the second capillary tube C2 and the second evaporation section E2 lie in a branch of the circuit parallel to that comprising the solenoid valve SV, the first capillary tube C1, and first evaporation section El. The junction P3 of one parallel branch is disposed downstream of the condenser CD and upstream of the solenoid valve SV, and the junction P4 is disposed downstream of both evaporation sections and upstream of the drier filter SF.

The operation of the refrigerator-freezer shown in Figure 1 is described hereinafter on the assumption that it is provided with the refrigeration fluid flow circuit of Figure 3 and the electrical circuit of Figure 5.

When both compartments 1 and 2 of the refrigerator-freezer are to be cooled, the switch 22 is closed by the thermostat Tl, while the switch 23 is changed over by the thermostat T2 into the position in which it closes the contacts 27 and 28: Consequently the motor 30 of the compressor CM operates and the solenoid valve SV is open because its solenoid 26 is energised. In the refrigeration fluid flow circuit, the fluid arrives entirely in the liquid phase at junction P3, from which junction a part of the fluid flows through the solenoid valve SV, into the first capillary tube C1 and into the first evaporation section El.The other part of the refrigeration fluid flows into the second capillary tube C2 and second evaporation section E2, before joining the first part at the junction P4, where the refrigeration fluid is entirely in the vapor phase. All of the fluid flows back from the junction P4 to the junction P3. When the thermostat T1 detects its break temperature, it opens the switch 22 causing the solenoid 26 to be de-energised and the solenoid valve SV closes. The thermostat T2 still holds the switch 23 in the previous position to ensure that the compressor motor continues to operate.Consequently the whole of the refrigeration fluid flows downstream from the junction P3 only through that branch of the circuit comprising the second capillary tube C2 and the second evaporation section E2, so that only the freezer compartment 2 of the refrigerator-freezer continues to be cooled. In the meantime, the first evaporation section defrosts without the need for operation of any special resistance heater by a combination of the fluid flow characteristics and the degrce of thermal insulation present. When the second thermostat T2 detects its break temperature, it causes the switch 23 to change over to the position (indicated by a dashed line in Figure 5) in which the contacts 27 and 29 are closed. Consequently the solenoid 26 is energised and the solenoid valve SV is open even during the time for which the compressor is at rest.Because of the natural circulation of refrigeration fluid in both the branches between the junctions P3 and P4, there can be a balance of the pressures in the various components of the refrigeration fluid flow circuit which can aid the starting of the compressor CM. This occurs when the thermostat T2 causes the 'switch 23 to close the contacts'27 and 28, and the thermostat T1 closes the switch 22.

As the two capillary tubes are connected in parallel while the solenoid valve is located upstream of only one of these, the solenoid valve is able to operate under optimum hydraulic conditions. The refrigeration fluid flows through it only in the liquid phase and substantially at its condensation temperature, of the order of 50"C. For this reason it is not necessary to thermally insulate the solenoid valve. In order to simplify the maintenance of the refrigerator-freezer, it has been found suitable to position the solenoid valve in the same space, usually to the rear of a cabinet of the refrigeratorfreezer, as that which houses the compressor. This space within the cabinet can be designed to be easily accessible. A solenoid valve of normal construction and thus of a low manufacturing cost and proven reliability can be used.

A further advantage, particularly evident in the first embodiment of the refrigeration fluid flow circuit, is that the solenoid valve is open (that is, its solenoid is energised) almost only at a time when the refrigeration compartment, at the higher operating tem perature, is to be cooled. It is therefore possible to use an auxiliary manual switch which (for example, during long holiday periods when the freezer compartment is full while the refrigeration compartment is practically empty) keeps the solenoid of the solenoid valve de-energised for the whole of this time. This has no undesirable influ ence on the operation of the freezer compartment and it can enable a daily saving of about 0.35 kilowatt hours of electricity to be achieved.

WHAT WE CLAIM IS:- 1. A refrigerator-freezer having a first compartment arranged for operation at a refrigeration temperature and a second com partment arranged for operation at a lower freezer temperature and having a refrigera tion fluid flow circuit comprising a compressor, a condenser, a first evaporation section associated with the first compart ment, a second evaporation section associ ated with the second compartment, a solenoid valve, and a first and a second capillary tube, wherein the two capillary tubes are connected in parallel and the solenoid valve is located upstream of only one of the-capillary tubes.

2. A refrigerator-freezer as claimed in Claim 1, wherein the solenoid valve is dis posed upstream of the said capillary tube, which opens into the first evaporation section.

3. A refrigerator-freezer as claimed' in Claim 1 or 2, wherein the first and second evaporation sections are connected in series and the capillary tube which in the circuit is not preceded by the solenoid valve opens into an intermediate point between the two evaporation sections.

4. A refrigerator-freezer as claimed in Claim 1 or 2, wherein the first capillary tube and first evaporation section, and the second capillary tube and second evaporation section respectively, are disposed in two parallel branches of the fluid flow circuit, which branches commence at a point downstream of the condenser and upstream of the solenoid valve and finish at a point down- stream of both the evaporation sections and 'upstream of the compressor.

5. A refrigerator-freezer as claimed in any one of the preceding Claims, wherein the capillary tubes are dimensioned for equal throughputs of the refrigeration fluid.

6. A refrigerator-freezer as claimed in any one of the preceding Claims, wherein the solenoid valve is accommodated in a space which also houses the compressor.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. capillary tube C1 and into the first evaporation section El. The other part of the refrigeration fluid flows into the second capillary tube C2 and second evaporation section E2, before joining the first part at the junction P4, where the refrigeration fluid is entirely in the vapor phase. All of the fluid flows back from the junction P4 to the junction P3. When the thermostat T1 detects its break temperature, it opens the switch 22 causing the solenoid 26 to be de-energised and the solenoid valve SV closes. The thermostat T2 still holds the switch 23 in the previous position to ensure that the compressor motor continues to operate.Consequently the whole of the refrigeration fluid flows downstream from the junction P3 only through that branch of the circuit comprising the second capillary tube C2 and the second evaporation section E2, so that only the freezer compartment 2 of the refrigerator-freezer continues to be cooled. In the meantime, the first evaporation section defrosts without the need for operation of any special resistance heater by a combination of the fluid flow characteristics and the degrce of thermal insulation present. When the second thermostat T2 detects its break temperature, it causes the switch 23 to change over to the position (indicated by a dashed line in Figure 5) in which the contacts 27 and 29 are closed. Consequently the solenoid 26 is energised and the solenoid valve SV is open even during the time for which the compressor is at rest.Because of the natural circulation of refrigeration fluid in both the branches between the junctions P3 and P4, there can be a balance of the pressures in the various components of the refrigeration fluid flow circuit which can aid the starting of the compressor CM. This occurs when the thermostat T2 causes the 'switch 23 to close the contacts'27 and 28, and the thermostat T1 closes the switch 22. As the two capillary tubes are connected in parallel while the solenoid valve is located upstream of only one of these, the solenoid valve is able to operate under optimum hydraulic conditions. The refrigeration fluid flows through it only in the liquid phase and substantially at its condensation temperature, of the order of 50"C. For this reason it is not necessary to thermally insulate the solenoid valve. In order to simplify the maintenance of the refrigerator-freezer, it has been found suitable to position the solenoid valve in the same space, usually to the rear of a cabinet of the refrigeratorfreezer, as that which houses the compressor. This space within the cabinet can be designed to be easily accessible. A solenoid valve of normal construction and thus of a low manufacturing cost and proven reliability can be used. A further advantage, particularly evident in the first embodiment of the refrigeration fluid flow circuit, is that the solenoid valve is open (that is, its solenoid is energised) almost only at a time when the refrigeration compartment, at the higher operating tem perature, is to be cooled. It is therefore possible to use an auxiliary manual switch which (for example, during long holiday periods when the freezer compartment is full while the refrigeration compartment is practically empty) keeps the solenoid of the solenoid valve de-energised for the whole of this time. This has no undesirable influ ence on the operation of the freezer compartment and it can enable a daily saving of about 0.35 kilowatt hours of electricity to be achieved. WHAT WE CLAIM IS:-

1. A refrigerator-freezer having a first compartment arranged for operation at a refrigeration temperature and a second com partment arranged for operation at a lower freezer temperature and having a refrigera tion fluid flow circuit comprising a compressor, a condenser, a first evaporation section associated with the first compart ment, a second evaporation section associ ated with the second compartment, a solenoid valve, and a first and a second capillary tube, wherein the two capillary tubes are connected in parallel and the solenoid valve is located upstream of only one of the-capillary tubes.

7. A refrigerator-freezer as claimed in

any one of the preceding Claims, having a first thermostat for controlling the temperature in the first compartment and a second thermostat for controlling the temperature in the second compartment, wherein said first thermostat actuates a switch which can be switched between a first position in which it allows energisation of the solenoid valve, and a second position in which it allows energisation of an electrical resistance heater for defrosting the first evaporation section and/or first compartment.

8. A refrigerator-freezer as claimed in Claim 7, wherein said second thermostat actuates a switch which controls a motor of the compressor.

9. A refrigerator-freezer as claimed in any one of Claims 1 to 6, having a first thermostat for controlling the temperature in the first compartment and a second thermostat for controlling the temperature in the second compartment, wherein said second thermostat actuates a switch which can be switched between a first position in which it allows energisation of a motor of the compressor and a second position in which it allows energisation of a solenoid of the solenoid valve.

10. A refrigerator-freezer as claimed in Claim 9, wherein said first thermostat actuates a switch which, when closed allows energisation of the solenoid of the solenoid valve, and when open causes de-energisation of this solenoid.

11. A refrigerator-freezer substantially as hereinbefore described and as illustrated in the accompanying drawings.