JP2008157595A - Refrigerator-freezer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To always operate a compressor near a maximum efficiency throughout the year in a refrigerator-freezer in which R290 (propane) is used as a refrigerant. <P>SOLUTION: This refrigerator-freezer uses a refrigerating cycle in which R290 (propane) is used as a refrigerant. The refrigerating cycle has a hermetic reciprocating compressor the rotational speed of which is controllable. The inside of the refrigerator-freezer is cooled by compressing the refrigerant in the cylinders of the compressor. The displacement of the cylinders of the compressor is so selected that the accumulated average number of revolutions of the compressor in a stable operation state in which the inside temperature is stably controlled within a specified temperature range is 30-40 rps. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigerator-freezer that uses R290 (propane) as a refrigerant.

Currently, R600a (isobutane) is mainly used as a refrigerant in a domestic refrigerator-freezer, and a hermetic compressor capable of controlling the rotation speed is used as a compressor. In addition, the use of R290 (propane) as a refrigerant has been studied (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 2002-267312

  However, conventionally, efficient compressor speed control of a compressor when R290 (propane) is used as a refrigerant has not been studied.

  The present invention has been made by paying attention to the above circumstances, and the object of the present invention is to allow the compressor to always operate near the maximum efficiency throughout the year in a refrigerator-freezer using R290 (propane) as a refrigerant. It is to provide a refrigerator-freezer.

  In order to solve the above-mentioned problems, the invention described in claim 1 includes a refrigeration cycle using R290 (propane) as a refrigerant, and the refrigeration cycle has a hermetic reciprocating compressor capable of controlling the rotational speed. In the refrigerator-freezer which cools the inside of the refrigerator by compressing the refrigerant in the cylinder of the compressor, the inside temperature is stably controlled within a predetermined temperature range. The cylinder volume is selected so that the accumulated average rotational speed of the compressor during operation is 30 to 40 rps.

  According to the present invention, the amount of power consumption can be kept to the minimum necessary, and the refrigeration for home use using the refrigerant R600a (isobutane), which is currently mainstream, without increasing noise. Compared to the refrigerator, the annual power consumption can be greatly reduced.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
FIG. 1 is a side sectional view showing a domestic refrigerator-freezer according to an embodiment of the present invention, and FIG. 2 is a cooling system diagram thereof.

  The refrigerator-freezer 1 includes a heat insulating box 2 and an inner box 3. The inside of the refrigerator-freezer 1 is divided into upper and lower parts by a heat insulating partition wall 4, and the upper side is a refrigerator compartment 30 and the lower part is a freezer compartment 40. Due to the heat insulating partition wall 4, the cold air in the refrigerator compartment 30 and the cold air in the freezer compartment 40 are completely independent, and the cold air is not mixed.

  The inside of the refrigerator compartment 30 is partitioned into a refrigerator compartment 6 and a vegetable compartment 7 by the refrigerator compartment plate 5. The inside of the freezer compartment 40 is composed of a first freezer compartment 8 and a second freezer compartment 9. Each chamber 6-9 is provided with an open / close door 51-54.

  A refrigerator compartment evaporator 10 and a refrigerator compartment cooling fan 11 are arranged on the back side of the vegetable compartment 7, and the refrigerator compartment cooling fan 11 is arbitrarily operated by changing the temperature inside the cabinet or opening and closing the door. The back side of the refrigerated storage chamber 6 is a cold air circulation path 12 for supplying cold air into the refrigerated chamber 30.

  A freezer compartment cooling fan 14 is disposed on the back side of the first freezer compartment 8, and a freezer compartment evaporator 13 is disposed on the back side of the second freezer compartment 9, and these first and second freezer compartments 8 are circulated by circulating cold air. , 9 is cooled.

  A machine room 15 is provided on the lower back side of the refrigerator 1. In this machine room 15, a compressor 16 and a condenser 17 constituting a refrigeration cycle as shown in FIG. 2 are arranged, and discharged from the compressor 16. After the passed refrigerant passes through the condenser 17, it flows through the flow path switched by the refrigerant switching mechanism of the three-way valve 18.

  A refrigerating capillary 19 and a refrigerating chamber evaporator 10 are sequentially connected to one outlet of the three-way valve 18, and a refrigerating capillary 20, a refrigerating chamber evaporator 13 and an accumulator 21 are sequentially connected to the other outlet of the three-way valve. A check valve 22 is connected to the outlet pipe of the accumulator 21 in the machine chamber 15, and the outlet side of the check valve 22 joins with the outlet pipe of the refrigerator compartment evaporator 10 to the suction side of the compressor 16. It is connected to the.

  The three-way valve 18 can alternately switch the flow path between the refrigerator compartment cooling system and the freezer compartment cooling system, and at the same time, can switch between the fully closed mode that simultaneously shuts off both flow paths and the fully open mode that opens. It is.

    The controller 60 controls the mechanical system such as the compressor 16, the cooling fans 11 and 14, the three-way valve 18, and the condenser fan 23. The controller 60 inputs signals from refrigerant temperature sensors, pressure sensors, and compressor speed sensors installed at various locations, and performs necessary control based on these signals, for example, automatic defrost control.

  Next, the cooling control operation of the refrigerator 1 configured as described above will be described.

  In the freezer compartment cooling mode, the refrigerant is decompressed by the freezing capillary 20 and enters the freezer compartment evaporator 13, cools the freezer compartment 40, and then returns to the compressor 16 again. That is, the refrigerant flows in the order of the freezing capillary 20, the freezing room evaporator 13, the accumulator 21, and the check valve 22, and the cold air circulates in the refrigerator by the operation of the freezing room cooling fan 14, and the first and second freezing rooms 8, 9 is cooled.

  On the other hand, when the three-way valve 18 is switched to enter the refrigerating chamber cooling mode, the refrigerant is decompressed by the refrigerating capillary 19, enters the refrigerating chamber evaporator 10, cools the refrigerating chamber 30, and then returns to the compressor 16 again. That is, the refrigerant flows in the order of the refrigerating capillary 19 and the refrigerating room evaporator 10, and cools the refrigerating storage room 6 and the vegetable room 7 by operating the refrigerating room fan 11.

  By the way, in the above-described refrigerator 1, R290 (propane) is used as the refrigerant, and the compressor 16 is used for a hermetically small reciprocating motion mounted with a DC motor capable of controlling the rotational speed.

  Hereinafter, the calorimeter test characteristics of the hermetic compact reciprocating compressor will be described. The cylinder volume of the compressor 16 is about 5 cc.

  3A, the condensation temperature is 38 ° C. (corresponding to the ambient temperature of the refrigerator-freezer is about 30 ° C.), B in the figure is the condensation temperature of 21 ° C. (corresponding to the ambient temperature of the refrigerator-freezer is about 15 ° C.), and the evaporation temperature is In either case, the measurement result of COP (coefficient of performance) when the rotational speed of the compressor 16 is changed at −23.3 ° C. is shown.

  In FIG. 3A, COP is high at 30 rps or higher, and the maximum efficiency is shown at around 40 rps. If it is less than 30 rps, the efficiency is low. In particular, the efficiency decreases significantly at 25 rps or less. The decrease in efficiency on the low speed side is significant because, in addition to the decrease in motor efficiency, R290 (Pump Pan) is a high-pressure refrigerant whose condensation pressure is 2.5 times or more that of R600a (isobutane). In addition, leakage loss between the piston and cylinder is large. Therefore, it is considered that the influence becomes more noticeable at a low speed at which the leakage time per rotation becomes longer. Even when the test was performed with the cylinder volume changed to 3.8 cc, 4.6 cc, and 5.5 cc, this tendency was the same, and this tendency did not change. If it exceeds 40 rps, the COP gradually decreases and the noise increases.

  Therefore. As a preferred method for power saving of the compressor for R290 (open mouth pan) under these conditions (summer summer assumption), considering that the refrigerator during actual use is subject to thermal load fluctuations, there is no door opening and closing at night etc. When it is small, it is preferably operated at 30 to 40 rps on the low speed side including the highest efficiency point (around 40 rps), and even if the door is opened and closed severely and the heat load increases, it is preferably 50 rps so that it does not deviate greatly from the highest efficiency point to the high speed side. It can be said that it is desirable to drive in the following.

  In FIG. 3, B shows the highest efficiency in the vicinity of 25 to 30 rps, and the decrease in efficiency is greater than 20 rps. The reason why the maximum efficiency point moves to the low speed side with respect to A is that the compressor leakage loss between the piston and the cylinder decreases due to the low condenser temperature, that is, the compressor discharge pressure. That is, the number of revolutions that causes a leakage loss equivalent to A moves to the low speed side, and the mechanical loss decreases as the speed decreases.

  It can be said that it is desirable to operate between 20-35 rps as a preferred usage for power saving of the compressor for R290 (bread bread) under this condition (presumed in winter).

  From the above, it is easily estimated that the COP curve in the condition between AB moves as a curve having the highest efficiency point on the arrow line in the figure.

  C in FIG. 3 is a characteristic when a compressor for a refrigerant R600a (isobutane) having a cylinder capacity of 10 cc class is measured under the same conditions as A with the refrigerant as R600a (isobutane).

  Unlike A, there is no drop on the low speed side and the efficiency is better on the low speed side. This is thought to be because the condensation pressure of R600a (isobutane) is very low, 40% or less of R290 (pouch van), and therefore the leakage loss of the compressor is basically small and the leakage loss is not so great even at low speeds. It is done. Therefore, it can be said that it is desirable to operate on the low speed side as much as possible as a preferred method for power saving of the compressor for R600a (isobutane) under this condition (summer summer assumption).

  FIG. 4 is a comparison of A and C in FIG. 3 with the horizontal axis as the refrigeration capacity.

  Assuming that the required refrigeration capacity in a refrigerator / freezer at an ambient temperature (room temperature) of 30 ° C. is 200 to 300 W, the operation is performed at 35 to 50 rps with a cylinder volume of 5 cc class for R290 (open mouth pan). In order to produce the same capacity in the 10 cc class for R600a (isobutane), it is necessary to operate at approximately 55 to 80 rps. Compared to the COP, the R290 (bread bread) is better than 10%. It has become.

  That is, when the compressors of the two models of this example are mounted in a refrigerator-freezer having a required refrigeration capacity of 200 to 300 W, the R290 (bread pan) is overwhelmingly saving power.

  An efficient operation is possible if the cylinder capacity for R600a (isobutane) is set to 15 to 20 cc and operation is performed so that the same capacity can be obtained even at low speed.

  However, the outer shape for R600a (isobutane) can be configured with approximately the same size as the outer shape of the 5 cc class for R290 (propane) from about 10 to 11 cc class. In addition to the economic problems (cost increase), the refrigerator room specifications increase the volume of the machine room, resulting in the fundamental disadvantage of a significant reduction in the effective internal volume. It's not right.

  By the way, as the compressor 16 of the refrigerator-freezer 1 described above, a cylinder having a cylinder capacity such that the integrated average rotational speed during the compression operation is 30 to 40 rps is selected under the following conditions.

  Conditions: JIS C 9801 (2006) “Characteristics and test method of household electric refrigerator and electric freezer”, Section 15 “Power consumption test”, test at room temperature 30 ℃ ± 1 ℃, from the start of measurement, door During stable operation that occurs (appears) after the opening / closing and load application ends (except before and after defrosting).

  FIG. 5 shows a method of “power consumption test” defined in JIS C 9801 (2006).

  In this test, after the operation is continued for at least 24 hours, the power consumption is measured for 24 hours. In the case of the automatic defrosting method, after the operation is continued for at least 24 hours from the start of the operation, the measurement of the power consumption is started from the end of the defrosting control that is first performed, and the measurement is performed for at least 24 hours.

  Further, when the cooling method is a cold air forced circulation method, opening and closing of the refrigerator door and the freezer door and loading of the load are performed after 2 hours have elapsed since the start of the measurement. The refrigerator door opens and closes once every 8 minutes, for a total of 35 times. The opening / closing angle of the refrigerator door is 90 ° ± 5 ° and the opening time is 10 seconds (the total opening time is 5 seconds or more). The freezer door opens and closes once every 40 minutes, for a total of 8 times. The open / close angle of the freezer door is 90 ° ± 5 ° and the opening time is 10 seconds (total opening time is 5 seconds or more).

  Here, the stable operation state is an operation state during 7 hours to 2 hours before the start of control of the defrosting control after the start of measurement of power consumption.

  FIG. 6 shows an example of how the rotational speed of the compressor 16 changes with time when the above-described “power consumption test” of the refrigerated refrigerator 1 is performed at room temperature of 30 ° C. ± 1 ° C. Is.

  This test simulates (assumes) the actual use state in a general household in the summer, and the refrigerator 16 operates the compressor 16 in the summer when the heat load is greatest in the normal use state of the year. It shows how the rotational speed changes.

    The rotation speed of the compressor 16 goes back and forth between 35 rps at the stable time and approximately 50 rps at the time of door opening and closing and loading. As indicated by A in FIG. 3, this means that the compressor 16 is always operated near the top of efficiency (state where there is little decrease in efficiency), including the vicinity of the highest efficiency point of 40 rps, and the most preferable operation in terms of power saving. You can see that it is one of the patterns.

  That is, this refrigerator-freezer 1 means that the most efficient operation can be performed at least in the summer when the heat load is greatest during normal use throughout the year.

    In terms of noise, the appearance of high speed operation in which the rotational speed of the compressor 16 exceeds 60 rps is not observed, and the rotational speed further decreases except in summer, so that quieter operation is possible throughout the year.

On the other hand, when this refrigerator-freezer 1 was subjected to the above-mentioned “power consumption test” at room temperature of 15 ° C. ± 1 ° C.,
The operating speed of the compressor 16 (not shown) is approximately between 20 and 35 rps. As shown in FIG. 3B, this includes the highest efficiency point of 25-30 rps of the compressor 16 and is always operated near the top of efficiency (state where there is little reduction in efficiency), which is most preferable in terms of power saving. You can see that this is one of the driving patterns.

  This test simulates (assumes) the actual winter usage in a general household. The refrigerator-freezer 1 is most efficient even in winter when the heat load is the lowest in normal usage throughout the year. It means that you can drive.

  When the refrigerator-freezer 1 is operated between a room temperature of 30 ° C. (summer) and a room temperature of 15 ° C. (winter), the heat load is reduced when the room temperature is lowered, so the rotational speed of the compressor 16 moves to the low speed side. However, since the temperature of the condenser 17 decreases as the rotational speed of the compressor 16 moves to the low speed side, the discharge pressure of the compressor 16 decreases. As a result, the compressor leakage loss between the piston and the cylinder is reduced, and the mechanical loss is also reduced as the sliding speed is lowered. Therefore, the highest efficiency point moves to the low speed side.

  That is, as the room temperature decreases, the rotational speed of the compressor 16 moves to the low speed side. With this movement, the maximum efficiency point of the compressor 16 also moves to the low speed side on the arrow line in FIG. By going, the operation state in the vicinity of the peak of efficiency (a state in which the efficiency decrease is small) is continued.

  As described above, in the “power consumption test” at room temperature of 30 ° C. assuming actual use in summer, the cumulative average rotational speed of the compressor in the stable operation state is from the highest efficiency point of the compressor (near 40 rps). Since the cylinder volume of the compressor is selected to be 30 to 40 rps corresponding to the low speed side, the compressor is always operated near the maximum efficiency throughout the year in the normal use state. Can be kept to the minimum necessary, and even for household refrigerators that use the refrigerant R600a (isobutane), which is currently the mainstream, the annual power consumption is greatly reduced as the size of the refrigerator increases. It becomes possible.

  In addition, except for special modes (rapid freezing, rapid ice making, etc.), the appearance of high-speed operation (such as the rotation speed exceeding 60 rps) of the compressor is suppressed even in summer, and quieter operation is possible throughout the year.

  Further, the compressor 16 of the refrigerator-freezer 1 described above is not limited to the conditions of JIS C 9801 (2006). For example, under the following conditions, the integrated average rotational speed during the compression operation is 30 to 40 rps. A cylinder with a large cylinder volume may be selected.

  Start at a room temperature of 30 ° C ± 1 ° C with no load in the refrigerator. After starting operation, without opening and closing the door, after defrosting control after 24 hours, after 4 hours To 2 hours before the next start of defrosting.

  Also in this case, the compressor is always operated near the maximum efficiency throughout the year in the normal use state, and the power consumption of the refrigerator-freezer 1 can be kept to the minimum necessary.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, you may delete some components from all the components shown by embodiment mentioned above. Furthermore, you may combine the component covering different embodiment suitably.

The figure which shows schematically the internal structure of the refrigerator-freezer which is one embodiment of this invention. The figure which shows the refrigerating-cycle apparatus of the freezer refrigerator of FIG. The figure which shows the result of the calorimeter test of the compressor single-piece | unit performed assuming the time of the power consumption amount test. The figure which compares and shows the refrigerating capacity of the refrigerator-freezer which uses R290 (propane) of FIG. 1, and the refrigerator-freezer which uses R600a (isobutane) as a refrigerant | coolant. The figure which shows the test method of power consumption. The figure which shows the change of the frequency | count of a driving | operation of a compressor when a power consumption test is performed at room temperature 30 degreeC.

Explanation of symbols

  1 ... Refrigerated refrigerator, 16 ... Compressor, 60 ... Control means

Claims (2)

It has a refrigeration cycle using R290 (propane) as a refrigerant, and this refrigeration cycle has a hermetic reciprocating compressor capable of controlling the rotation speed, and by compressing the refrigerant in a cylinder of the compressor, In the refrigerator-freezer that cools the interior,
Cylinders of the compressor so that the integrated average rotation speed of the compressor is 30 to 40 rps in a stable operation state at an ambient temperature of 30 degrees ± 1 ° C where the internal temperature is stably controlled within a predetermined temperature range. A refrigerator-freezer characterized in that the volume is selected. Equipped with a control means for performing automatic defrosting control,
The stable operation state is the power consumption in the test of ambient temperature + 30 ° C. ± 1 ° C. in Section 15 “Power Consumption Test” of JIC C 9801 (2006) “Characteristics and Test Methods of Home Electric Refrigerator and Electric Freezer”. The refrigerator-freezer according to claim 1, wherein the refrigerator is in an operating state between 7 hours and 2 hours before the start of defrosting after the measurement of the amount is started.

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