JP2012127514A - Refrigerator-freezer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerator-freezer being further excellent in energy saving by eliminating the number of defrosting frequency corresponding unnecessary defrosting during defrosting a second evaporator of the refrigerator-freezer loading binary freezing cycle.SOLUTION: The refrigerator-freezer includes: a chill room for chilling and preserving goods, a freezing compartment for freezing and preserving goods, a first compressor which operates a first freezing cycle for distribution of first refrigerant, a first evaporator which is arranged at a low temperature part of the first freezing cycle for cooling the chill room, a second compressor for operating a second freezing cycle for distribution of second refrigerant, a second evaporator which is arranged at a low temperature part of the second freezing cycle for cooling the freezing compartment, a control part, and a plurality of detectors which detect ambient temperature of the refrigerator-freezer, compartment temperature of the freezing compartment, ambient humidity of the refrigerator-freezer, and opening/closing of a freezing compartment door. The control part starts the defrosting of the second evaporator in a combination of two defrosting methods of irregular time defrosting based on a plurality of detectors and periodical defrosting based on integrated operation time of the refrigerator-freezer.

Description

  The present invention relates to a refrigerator-freezer equipped with a two-way refrigeration cycle and an operation method thereof.

  Refrigeration refrigerators that use a two-way refrigeration cycle have been mainly used for large-sized businesses, but in recent years, they have also been adopted for home use. By using two compressors as the background, the two compressors can be made into independent systems for the refrigerator compartment and the freezer compartment, respectively, and the refrigerator compartment and the freezer compartment can be made independent. Moisture contained in the outside air flowing into the room, or water of foods, vegetables, etc. stored in the refrigeration room no longer enters the freezing room, resulting in less frost formation.

  On the other hand, in order to defrost frost that has formed on the evaporator in the freezer compartment, there is a method in which a heater is disposed below the evaporator and the frost attached to the evaporator is defrosted by the heat of the heater. There are two types of defrosting methods, and there are two defrosting methods: indefinite time defrosting based on the temperature detecting means of the evaporator, and scheduled defrosting based on a predetermined accumulated operation time.

  For example, Japanese Patent Laid-Open No. 10-89834 (Patent Document 1) describes that defrosting of an evaporator for a freezer compartment is performed by indefinite time defrosting. Specifically, the outside air temperature and the number of doors open / closed during the defrosting interval are counted, and the expected frost amount is calculated from the average outside air temperature, the number of doors open / closed, and the amount of moisture that has entered through the door gap after the end of the defrosting interval. calculate. Further, the actual frost amount P is calculated from the defrosting time. It is described that the defrosting interval period is extended or shortened from the actual frost amount P and the expected frost amount M.

  Japanese Patent Laying-Open No. 2002-62026 (Patent Document 2) describes that defrosting is performed by scheduled defrosting in which the defrosting operation mode is executed every predetermined operation integration time of the compressor.

Japanese Patent Laid-Open No. 10-89834 JP 2002-62026 A

  However, the conventional two-way refrigeration cycle is not an efficient combination of the two defrosting methods.

  In the defrosting method disclosed in Patent Document 1, the expected frost amount is calculated from the average outside air temperature, the number of doors opened and closed, and the amount of moisture that has entered through the door gap after the end of the defrosting interval. Further, the actual frost amount P is calculated from the defrosting time. The defrosting interval period is extended or shortened from the actual frost amount P and the expected frost amount M. However, in the prediction calculation of the frost amount during the defrost control, the standard for the prediction calculation of the moisture amount entering the cabinet is limited to specific conditions, so the frost amount is not accurately calculated and is therefore appropriate. There is a possibility that defrosting will not be performed frequently.

  Moreover, since the defrost method disclosed by the said patent document 2 performs a defrost operation mode for every predetermined | prescribed operation integration time of a compressor, since it defrosts regardless of the presence or absence of the amount of actual frost formation, There is a drawback that the defrosting is insufficient when the cost increases or the amount of frost formation increases rapidly.

  This invention is made | formed in view of the said subject, and it aims at suppressing frequent defrost and suppressing unnecessary defrost by performing it by combining fixed time defrost and indefinite time defrost. To do.

In order to solve the above-mentioned problems, a refrigerator-freezer according to the present invention includes a refrigerating room for storing stored items in a refrigerator, a freezing chamber for storing stored items in a frozen state, and a first compression that operates a first refrigeration cycle through which a first refrigerant flows. A first evaporator that is disposed in a low temperature part of the first refrigeration cycle and cools the refrigerator compartment;
A second compressor that operates a second refrigeration cycle through which the second refrigerant flows, a second evaporator that is disposed in a low temperature part of the second refrigeration cycle and cools the freezer compartment, a control unit, and a surrounding of the refrigerator / freezer In the refrigerator / freezer comprising a temperature, a temperature in the freezer compartment, an ambient humidity of the refrigerator / freezer, and a plurality of detecting means for detecting opening / closing of the freezer compartment door, the control unit is based on the plurality of detecting means. The defrosting of the second evaporator is started by a combination of two defrosting methods of unfixed time defrosting and fixed time defrosting based on the accumulated operation time of the refrigerator-freezer.

  According to the present invention, the defrosting can be efficiently performed by using two defrosting methods of the indefinite time defrosting based on the temperature value by the temperature detecting means and the timed defrosting based on the operation cumulative time. Is possible.

Side surface sectional drawing and control block diagram of the refrigerator-freezer of embodiment of this invention. The whole block diagram of the two-way freezing cycle of the refrigerator-freezer of the embodiment of the present invention. The timing chart of the fixed time defrost of the refrigerator-freezer of embodiment of this invention, and an indefinite time defrost. The timing chart of the fixed-time defrost and the indefinite-time defrost of the refrigerator-freezer of other embodiment of this invention.

  Hereinafter, the present invention will be described based on the embodiments.

FIG. 1 is a side sectional view and a control configuration diagram of a refrigerator-freezer according to an embodiment of the present invention. The main body of the refrigerator-freezer 1 has a heat insulating box 3. In the upper part of the heat insulating box 3, a refrigerator compartment 2 for storing stored items in a refrigerator is arranged. The front surface of the refrigerator compartment 2 is opened and closed by a rotating refrigerator compartment door 2a.
Below the refrigerating room 2, a freezing room 4 for freezing and storing stored items is disposed via a heat insulating wall 7. The front surface of the freezer compartment 4 is opened and closed by a drawer-type freezer compartment door 4a.

  The heat insulating wall 7 has a heat insulating performance equivalent to that of the peripheral wall (upper wall, bottom wall, side wall, and back wall) of the heat insulating box 3. Thereby, heat exchange between the refrigerator compartment 2 and the freezer compartment 4 is suppressed.

  A machine room 5 in which the first compressor 11 and the second compressor 21 are arranged is provided at the lower rear of the freezer compartment 4. A first refrigeration cycle 10 and a second refrigeration cycle 20 (see FIG. 2), which will be described in detail later, are operated by the first compressor 11 and the second compressor 21, respectively.

  A first evaporator 14 connected to the first compressor 11 is disposed on the back surface of the refrigerator compartment 2, and a refrigerator refrigerator 15 is disposed above the first evaporator 14. A second evaporator 24 connected to the second compressor 21 is disposed on the back surface of the freezer compartment 4, and a freezer compartment blower 25 is disposed above the second evaporator 24.

  Cold air cooled by exchanging heat with the first evaporator 14 is discharged to the refrigerator compartment 2 by the refrigerator refrigerator 15. The cold air flows through the refrigerator compartment 2 and returns to the first evaporator 14. Thereby, the refrigerator compartment 2 is cooled. The cold air cooled by exchanging heat with the second evaporator 24 is discharged into the freezer compartment 4 by the freezer blower 25. The cold air discharged into the freezer compartment 4 flows through the freezer compartment 4 and returns to the second evaporator 24. Thereby, the freezer compartment 4 is cooled.

  In addition, a defrost heater 8 using a glass tube heater is provided immediately below the bottom surface of the second evaporator 24. When the second evaporator 24 is frosted, the defrosting is performed by warming the second evaporator 24 from below with the defrost heater 8.

  In the refrigerator-freezer 1, an electrical component assembly (not shown) including an electrical circuit is disposed in the machine room 5. A control unit 6 is provided in the electrical component assembly.

  The control unit 6 of the refrigerator 1 includes an ambient temperature detection means T1, a second evaporator temperature detection means T2, a first compressor control means E1, and a second compressor control means E2. The refrigerating room blower control means F1 of the refrigerating room blower 15, the freezing room blower control means F2 of the freezing room blower 25, the freezing room door open / close detection means G1, and the ambient humidity detection means H1 are configured. The control unit 6 controls the operation of the refrigerator-freezer 1 from the detection signals from the plurality of detection means.

  Regarding the ambient temperature detection means T1, the second evaporator temperature detection means T2, and the freezer compartment temperature detection means T3, the temperature is measured by a temperature sensor such as a thermistor and is input to the control unit. The compressor control means E1 performs inverter control, and the compressor integrated operation time calculation means E2 performs control based on the compressor integrated operation time. The refrigerator compartment blower control means F1 and the freezer compartment blower control means F2 change the energization to the blower to control the rotational speed of the blower. The freezer compartment door open / close detection means G1 detects the open / close state of the freezer compartment door 4a by a door switch or the like provided in the heat insulating box 3 in contact with the freezer compartment door 4a, and the detection signal of the freezer compartment door 4a is detected by the control unit. Counts the number of opening and closing. As for the ambient humidity detecting means H1, the humidity is measured by a humidity sensor or the like and input to the control unit. The humidity sensor is fixed to the humidity sensor holder behind the upper surface of the heat insulating box 3, and the humidity sensor holder is fixed to the upper surface of the heat insulating box 3 with a fastener. In the ambient temperature detection means T1, the thermistor is fixed to the thermistor holder behind the upper surface of the heat insulating box 3, and the thermistor holder is fixed to the upper surface of the heat insulating box 3 with a fastener. As for the second evaporator temperature detecting means T2, a thermistor is used, the thermistor is fixed to the thermistor holder, and the thermistor holder is fixed to the aluminum fin of the second evaporator 24. As for the freezer compartment temperature detection means T3, a thermistor is used, the thermistor is fixed to the thermistor holder, and the thermistor holder is fixed to the inner surface of the freezer compartment 4.

  FIG. 2 is an overall configuration diagram of a two-way refrigeration cycle of the refrigerator-freezer according to the embodiment of the present invention. A refrigeration cycle 30 of the refrigerator 1 includes a first refrigeration cycle (also using a high-temperature refrigeration cycle) 10 and a second refrigeration cycle (also using a low-temperature refrigeration cycle) 20 connected by an intermediate heat exchanger 31. It is a cascaded dual refrigeration cycle. In FIG. 2, the flow of the refrigerant in the high temperature refrigeration cycle 10 is indicated by a solid line arrow (P direction), and the low temperature refrigeration cycle 20 is indicated by a broken line arrow (Q direction). One of the first compressor 11, the first condenser 12, the first expansion device 13, the first evaporator 14, and the first heat exchange unit 31 a of the intermediate heat exchanger 31 constitutes the high-temperature refrigeration cycle 10. The other, the second compressor 21, the second condenser 22, the second expansion device 23, the second evaporator 24, and the second heat exchange part 31 b of the intermediate heat exchanger 31 constitute the low temperature refrigeration cycle 20. The first heat exchange part 31a and the second heat exchange part 31b are formed adjacent to each other, are formed so as to be able to exchange heat with each other through a boundary wall, and are embedded in the heat insulating material 9 of the heat insulating box 3 of the refrigerator-freezer 1. ing.

  The intermediate heat exchanger 31 is composed of a double pipe having an inner pipe and an outer pipe embedded in the back wall of the heat insulating box 3 (see FIG. 1), and is a U-shaped pipe that extends in the vertical direction and bends at the lower end. It is formed. The first refrigerant flows through the inner pipe of the double pipe to form the first heat exchange part 31a, and the second refrigerant flows through the outer pipe to form the second heat exchange part 31b. Although the 1st heat exchange part 31a is not shown in figure, a refrigerant | coolant inflow port and a refrigerant | coolant outflow port are formed in an upper end. Although the 2nd heat exchange part 31b is not illustrated, similarly, a refrigerant inflow mouth and a refrigerant outflow mouth are formed in the upper end, and the distribution direction of the 1st heat exchange part 31a and a refrigerant is the reverse direction.

  Note that the first condenser 12 of the high-temperature refrigeration cycle 10 and the second condenser 22 of the low-temperature refrigeration cycle 20 are not shown in FIG. It is fixedly attached to an outer box plate 32 (see FIG. 1), which is a metal plate that covers the back and side surfaces of the heat insulating box 3.

In the present embodiment, the same refrigerant such as isobutane is used for the first refrigerant and the second refrigerant.
1 and 2, when the first compressor 11 is operated by the compressor control means E1, the refrigerant of the high-temperature refrigeration cycle 10 is compressed by the first compressor 11, and then flows into the first condenser 12. Here, the surrounding air is deprived of heat and condensed. The refrigerant liquefied by the first condenser 12 is guided to the first expansion device 13 composed of a capillary tube, and is decompressed and expanded by the first expansion device 13 to become low-temperature wet steam having a low dryness. The refrigerant which has become low-temperature wet steam flows into the first evaporator 14 installed in the refrigerator compartment 2 of the refrigerator 1 and is circulated by the refrigerator compartment fan 15 controlled by the refrigerator compartment fan control means F1. It takes heat from the cold air in the refrigerator compartment 2 and evaporates, resulting in wet steam with a higher dryness. Further, the wet vapor state refrigerant is led to the first heat exchanging portion 31a side of the intermediate heat exchanger 31, and evaporates while taking heat of condensation from the refrigerant of the second heat exchanging portion 31b by the intermediate heat exchanger 31. . Next, the evaporated refrigerant gas returns to the first compressor 11.

  As described above, the first evaporator 11 and the first heat exchanging portion 31a of the intermediate heat exchanger 31 are operated by driving the first compressor 11 to cool the refrigerator compartment 2 of the refrigerator 1 and at the same time, the intermediate heat exchange. The heat from the second heat exchange part 31b of the vessel 31 is absorbed.

  On the other hand, when the second compressor 21 is operated by the compressor control means E1 during the operation of the first compressor 11, the refrigerant of the low temperature refrigeration cycle 20 is compressed by the second compressor 21, and then the second condensation is first performed. Flows into the vessel 22 where it dissipates heat to the surrounding air and the temperature drops. The refrigerant radiated by the second condenser 22 is guided to the second heat exchanging portion 31b side of the intermediate heat exchanger 31, and the intermediate heat exchanger 31 is deprived of condensation heat and condensed. The condensed refrigerant in the liquid state is guided to the second expansion device 23 composed of a capillary tube, and decompressed and expanded by the second expansion device 23 to become low-temperature wet steam. The refrigerant that has become low-temperature wet steam flows into the second evaporator 24 installed in the freezer compartment 4 of the refrigerator 1 and is circulated by the freezer compartment fan 25 controlled by the freezer compartment fan control means F2. It takes heat from the cold air in the freezer compartment 4 and evaporates. The refrigerant gas flowing out from the second evaporator 24 returns to the second compressor 21.

  In the refrigerator-freezer 1 having the above-described configuration, when the refrigerator compartment 2 and the freezer compartment 4 are cooled, the first refrigerant and the second refrigerant flow through the refrigerant pipe by driving the first compressor 11 and the second compressor 21. The first compressor 11 and the second compressor 21 compress the first refrigerant and the second refrigerant, respectively, to high temperature and high pressure, and the first expansion device 13 and the second expansion device 23 respectively store the first refrigerant and the second refrigerant. Depressurize and expand to low temperature and low pressure.

  Accordingly, the first refrigeration cycle 10 until the first refrigerant and the second refrigerant flow out of the first compressor 11 and the second compressor 21 and flow into the first expansion device 13 and the second expansion device 23, respectively. It becomes the high temperature part of the second refrigeration cycle 20. Until the first refrigerant and the second refrigerant flow out of the first expansion device 13 and the second expansion device 23 and flow into the first compressor 11 and the second compressor 21, respectively, 2 It becomes a low temperature part of the refrigeration cycle 20.

  The refrigerator-freezer 1 keeps the temperature of the 2nd evaporator 24 falling to the setting freezing temperature (for example, -20 degreeC) at the time of a stable operation after an operation start. Therefore, a part of the moisture in the room air in the freezer compartment 4 becomes frost and adheres to the second evaporator 24. As the operation time becomes longer, if the frost formation exceeds a certain amount, the heat exchange efficiency of the second evaporator 24 becomes worse, so defrosting is necessary.

  FIG. 3 is a timing chart of scheduled defrosting and indefinite defrosting of the refrigerator-freezer according to the embodiment of the present invention. The defrost control according to the present invention is a combination of the scheduled defrost that is the first defrost control method and the indefinite time defrost that is the second defrost control method.

  When the operation integration time reaches the first predetermined integration time A from the start of the operation of the refrigerator 1 or immediately before the defrosting (either defrosting at fixed time or defrosting at irregular time), the defrosting heater 8 is energized, and the fixed time is reached. Start defrosting (start at point X).

  Before the first predetermined accumulated time A elapses, the defrosting by the second defrosting method is started after the operation of the refrigerator-freezer or when the predicted frosting amount from the previous defrosting reaches the predetermined amount W. (Start at point Y). Next, when the predicted frost formation amount from the previous defrosting is less than the predetermined amount W and the operation integration time has passed the first predetermined integration time A, the defrost heater 8 is energized to perform the regular defrosting. Start (start at point Z). The time from the start of defrosting to the end of defrosting ends when the temperature of the second evaporator 24 detected by the second evaporator temperature detecting means T2 reaches a predetermined temperature. In addition, for both the regular defrosting and the irregular defrosting, the count of the compressor integrated operation time is reset to zero seconds immediately after the completion of the defrosting, and the counting is started from zero seconds.

  FIG. 4 is a timing chart of scheduled defrosting and indefinite defrosting of a refrigerator-freezer according to another embodiment of the present invention. FIG. 4 is the same as FIG. 3 except that the second predetermined integration time B is added to FIG.

  According to the present invention, the second predetermined integrated time B is set for the start determination of indefinite time defrosting, and the first predetermined integrated time A is set longer than the second predetermined integrated time B. If the accumulated operation time of the refrigerator / freezer is not longer than the second predetermined accumulated time B from the previous defrosting, the indefinite time defrosting is not performed. Since the room temperature of the freezer compartment 4 has risen in the second predetermined accumulated time B in the previous defrosting, the room temperature of the freezer compartment 4 will rise further if the defrosting is performed at an indefinite time. This is the time for returning to or approaching the room temperature of the freezing room 4 before frost. For example, the second predetermined integrated time B may be set to be equal to or less than half the time of the shortest defrosting interval (from the count start immediately before defrosting to the start of indefinite time defrosting). As an example, you may set to less than half of the time from the count start after the defrost completion which started at the X point in FIG. 3 to the indefinite time defrost start (Y point).

  Next, the fixed-time defrosting and the indefinite-time defrost will be specifically described.

  The fixed-time defrosting starts the fixed-time defrosting that is the first defrosting method after the operation of the refrigerator-freezer 1 or when the compressor integrated operation time reaches the first predetermined integrated time A from the previous defrosting. The defrosting is completed when the temperature of the second evaporator 24 detected by the second evaporator temperature detecting means T2 reaches a predetermined temperature.

  Indefinite time defrosting is the second defrosting when the predicted amount of frost formation is greater than or equal to the predetermined amount W after the start of the operation of the refrigerator-freezer or before the first predetermined integration time A has elapsed from the previous defrosting. Indefinite time defrosting is started. The indefinite time defrosting is terminated when the temperature of the second evaporator 24 detected by the second evaporator temperature detecting means T2 reaches a predetermined temperature, similarly to the timed defrosting. The predetermined amount W is a value determined in advance according to the performance of the second evaporator 24 and the like.

Here, the calculation of the predicted frost amount will be specifically described.
The number of times of opening and closing the freezer compartment door 4a, the absolute humidity of the air flowing into the freezer compartment door 4a, the freezer compartment capacity, and the air in the compartment per opening and closing of the freezer compartment door 4a From the rate at which the outside air is switched, the air inside the freezer compartment 4 and the outside air are exchanged, and the moisture contained in the outside air is cooled to the inside temperature of the freezer compartment 4. In doing so, it calculates by calculating the moisture to condense. First, let Xo be the absolute humidity, ρ be the air density, V be the internal volume of the freezer compartment 4, and P be the rate at which the outside air and the internal air are interchanged by one opening and closing. At this time, the amount of moisture Q entering the cabinet by one opening and closing is
Q = Xo × ρ × V × P
It becomes the calculation of.

As an example, the outside air temperature is 29.5 ° C., the outside air relative humidity is 85%, the freezer compartment capacity V is 148 L, the freezer compartment temperature is −18 ° C., and the open air and freezer compartment 4 are opened and closed once. When the ratio P at which the internal air is exchanged is 100%, P = 1 is calculated. The absolute humidity Xo of air having a temperature of 29.5 ° C. and a relative humidity of 85% is 22.5 g / kg, and the air density ρ is 0.001203 kg / L.
qo = 22.5 × 0.001203 = 0.0270675 (g / L)
It becomes the calculation of.

If the internal volume of the freezer compartment 4 is 148L and the outside air and the internal air of the freezer compartment 4 are all exchanged by one opening and closing, P = 1, and the amount of moisture Qo entering the inside by one opening and closing is Qo = qo * V * P = 0.0270675 * 148 * 1 = 4.000599 (g)
It becomes the calculation of.

Next, when the saturated water vapor amount at the internal temperature is qi and the saturated water amount is Qi, the water amount Q condensed when the internal temperature is lowered to the original temperature is:
Q = (Xo × ρ−qi) × V × P = Qo−qi × V × P = Qo−Qi
It becomes the following formula.

As an example, since the saturated water vapor amount qi at the freezer compartment 4 temperature of −18 ° C. is 0.00180 g / L, the amount of water Qi that can be included in 148 L of indoor air is 0.00180 × 148 = 0.2664 g. .
Therefore, if moisture is condensed and the amount of moisture finally frosted on the evaporator is Q1,
Q1 = Qo-Qi = 4.000599-0.2664 = 3.73959 (g)
It becomes the calculation of.

Furthermore, in addition to this 3.7 g, if the amount of moisture that directly condenses on the inner wall surface of the freezer compartment 4 while the freezer compartment door 4a is open is Q2, Q2 is about 3. If it is 7g, if the amount of frost formation in opening and closing of the freezer compartment door 4a once is Qt,
Qt = Q1 + Q2 = 3.7 + 3.7 = 7.4 (g)
The amount of frost formation.

When the freezer door 4a is opened and closed about 30 times per day, and the compressor integrated operation time for 2 days does not reach the first predetermined time A,
Qt = 7.4 × 30 × 2 = 444 (g)
The amount of frost formation will occur.

  This numerical value is assumed to be the amount of frost formation that significantly reduces the cooling performance of the freezer compartment 4. When frost formation grows and the amount of frost formation that affects the heat exchange performance is reached, defrosting at indefinite times is required. Therefore, as an example, a case will be described in which the predicted predetermined amount W of the amount of frost that needs defrosting at irregular times is set to 350 g from experimental data and the like. In addition, from the amount of frost formation, the 1st predetermined integration time A by fixed-time defrosting shall be 3.0 days as an example.

The time N until the above-mentioned indefinite time defrosting is
N = 350 ÷ (Qt ÷ 2) = 350 ÷ (444 ÷ 2) = about 1.58 (days)
It becomes the calculation of.

  The indefinite time defrosting is performed about 1.58 days after the previous defrosting. It is about half the time of 3.0 days, which is the first predetermined accumulated time A in the regular defrosting. In the above description, when the frosting progresses until 3.0 days of the scheduled defrosting, the cooling performance of the freezer compartment 4 is significantly reduced. By performing definite time defrosting when the predicted predetermined amount W reaches 350 g or more, it is possible to efficiently maintain the temperature cooling performance of the freezer compartment 4 without significantly reducing the cooling performance. Moreover, as an example, by setting the second predetermined accumulated time B to 0.6 days, defrosting at an indefinite time will be started after at least 0.6 days have passed since the previous defrosting. It is possible to prevent a significant increase in the temperature inside the freezer compartment 4.

  The moisture condensed directly to the inner wall surface of the freezer compartment 4 while the freezer compartment door 4a is opened is condensed as the frost mainly adheres to the second evaporator 24 as time passes. Is integrated for each door opening / closing as the amount of frost formation per door opening / closing, the predicted frosting amount after the start of operation of the refrigerator-freezer 1 or from the previous defrosting can be obtained. Note that the rate P at which the outside air and the inside air of the freezer compartment 4 are switched by one opening and closing depends on the opening time of the freezer compartment door 4 a of the freezer compartment 4.

  Furthermore, most of the moisture that is directly condensed on the inner wall surface of the freezer compartment 4 while the freezer compartment door 4a is open is finally attached to the second evaporator 24 as frost. It is included as a part. The moisture that directly condenses on the inner wall surface per opening and closing of the freezer compartment door 4a is calculated from the surface area inside the warehouse, the outside air temperature and the outside air humidity, and the opening time of the freezer compartment door 4a. The amount of dew condensation calculated here plus the amount of condensed water according to the above formula is the amount of frost formation per opening and closing of the freezer compartment door 4a, and this value is calculated for each opening and closing of the freezer compartment door 4a. By integrating, the predicted amount of frost formation after the start of operation of the refrigerator-freezer 1 or from the previous defrost to the next defrost is calculated.

  As described above, the defrosting method based on the compressor accumulated operation time is the first defrosting method, and the defrosting method based on the predicted frost amount is the second defrosting method. Is combined with the second defrosting method at an appropriate frequency corresponding to the decrease in the amount of frost formation of the second evaporator 24 in the refrigerator 1 having the independent cold air circuit in the refrigerator compartment 2 and the freezer compartment 4. Defrost control can be realized. The first defrosting method based on the compressor integrated operation time mainly used can reduce the number of times compared to the frequency of defrosting in a refrigerator-freezer having a single cold circuit in the conventional refrigerator compartment 2 and freezer compartment 4. It is possible to reduce the power consumption used for defrosting and to save energy. Furthermore, by using the second defrosting method based on the predicted frost formation amount, it is possible to appropriately defrost even in a situation where frost formation on the evaporator is remarkably increased, and without reducing the cooling efficiency. In addition, the cooling operation in the freezer compartment 4 can be performed. Thus, by combining the defrosting by the 1st defrosting method and the 2nd defrosting method, it is excellent in energy-saving performance and can provide the refrigerator-freezer which can maintain high cooling efficiency.

  The prediction of the amount of frost formation is based on the number of times the freezer compartment door 4a is opened and closed, the absolute humidity of the air flowing into the compartment, the compartment volume, and the inside of the freezer compartment 4a per opening and closing of the freezer compartment door 4a. By deriving from a combination of a plurality of conditions such as the rate at which the air and the outside air are switched, it is possible to calculate a predicted value of the amount of frost formation that is close to actual use.

  Moreover, this invention is the refrigerator-freezer 1 provided with the calculation means which calculates the opening time of the freezer compartment door 4a, Comprising: The air in the freezer compartment 4 warehouse and the outside of the refrigerator outside the freezer compartment door 4a are opened and closed once. The rate at which the air is replaced may be calculated from the opening time per opening and closing of the freezer compartment door 4a. By detecting the opening time of the freezer compartment door 4a every time the freezer compartment 4 is opened and closed, the rate of air exchange is reduced when the opening time is short, and the rate of air exchange is increased when the opening time is long. The amount of moisture entering the freezer compartment 4 can be calculated more accurately, and the accuracy of the predicted frost amount can be increased.

  Moreover, this invention is the refrigerator-freezer 1 provided with the calculation means which calculates the opening time of the freezer compartment door 4a, Comprising: In calculation of the estimated amount of frost formation in a 2nd defrost method, the opening time of the freezer compartment door 4a To calculate the amount of moisture condensed on the inner surface of the freezer compartment 4 when the freezer door 4a is opened, the amount of moisture, the number of times the freezer door 4a is opened and closed, the absolute humidity of the air flowing into the refrigerator, and the freezer compartment 4 It is possible to predict the amount of frost formation from the internal capacity of the storage room and the rate at which the air inside the freezer compartment 4 and the air outside the compartment are exchanged per opening and closing of the freezer compartment door 4a.

  When the outside air enters the inside of the freezer compartment 4 by opening and closing the door, the moisture contained in the outside air is cooled in the inside of the compartment, and dew condensation occurs on the wall surface inside the compartment. Since this condensation will eventually adhere as frost to the evaporator, which is the coldest part in the cabinet, it is possible to improve the accuracy of the measurement frost amount by incorporating this moisture content into the prediction calculation of the frost amount. It is.

  Further, according to the present invention, the second defrosting method stops the cooling of the freezer compartment 4 and operates the defrosting means when the predicted frost formation amount from the previous defrosting end time reaches the predetermined amount W. Since defrosting of the second evaporator is performed, it is possible to perform defrosting at an appropriate frequency in response to a situation in which the amount of frost formation on the second evaporator is remarkably increased.

  Further, the present invention resets the compressor integrated operation time once the defrosting is completed, regardless of which of the first defrosting method and the second defrosting method is used, By starting counting from seconds, defrosting at an abnormal frequency can be avoided.

  In addition, as shown in FIG. 1, the first compressor 11 is also stopped and disposed in the refrigerator compartment 2 when the second evaporator 24 is defrosted by the first defrosting method or the second defrosting method. The air in the refrigerator compartment 2 is circulated by the refrigerator refrigerator 15, and the frost adhering to the first evaporator 14 is removed by the air passing through the first evaporator 14. The air circulating through the refrigerator compartment 2 melts the frost of the first evaporator 14 and absorbs moisture.

  Thus, the temperature fluctuation in the refrigerator compartment 2 during the defrosting can be suppressed by also performing the defrosting of the first evaporator 14 when the second evaporator 24 is defrosted. When power consumption can be suppressed by performing defrosting of the refrigerator compartment 2 using the air blowing means in the refrigerator compartment 2, the moisture adhering to the first evaporator 14 as frost is circulated into the refrigerator compartment 2 at the same time. By doing so, the humidification effect to the refrigerator compartment 2 can be expected.

  On the other hand, in the second predetermined accumulated time B, since the room temperature of the freezer compartment 4 has been raised by the previous defrosting, the room temperature of the freezer compartment 4 is further increased if the defrosting is performed at an indefinite time. The room temperature of the freezer compartment 4 before defrosting can be returned to or approached, and the quality deterioration of the food due to the temperature rise in the freezer compartment 4 can be prevented.

  Further, the defrosting of the first evaporator 14 may be performed mainly by air circulation in the refrigerating chamber 2 by the ventilation of the refrigerating chamber blower 15 disposed in the refrigerating chamber 2 while the first compressor 11 is stopped.

  Further, when the second evaporator 24 is defrosted, the first evaporator 14 is also defrosted at the same time, so that the air circulating in the refrigerator compartment 2 melts the frost of the first evaporator 14 and absorbs moisture, thereby refrigeration. There is a humidifying effect on the chamber 2.

  Further, when only one of the high-temperature refrigeration cycle 10 and the low-temperature refrigeration cycle 20 is operated, the efficiency of the intermediate heat exchanger 31 is reduced, but the intermediate heat exchanger 31 is not used by stopping both cycles, and then defrosting is performed. The refrigerator-freezer 1 can be operated with high efficiency by using both cycles during the operation of the refrigeration cycle after completion.

  Furthermore, since the first predetermined integrated time A in the case of scheduled defrosting can be set longer than in the case of only the fixed time defrost without providing indefinite time defrosting, power consumption is reduced. It becomes possible to do.

  Furthermore, by setting the operation integration time until the start of defrosting at indefinite time longer than the second predetermined integration time B, from the state in which the temperature in the freezer compartment 4 has increased due to the previous defrosting, The temperature can be lowered.

  In the present embodiment, the same refrigerant such as isobutane is used for the first refrigerant and the second refrigerant, but different refrigerants may be used. At this time, the boiling point of the first refrigerant may be higher than the boiling point of the second refrigerant. Thereby, the 2nd refrigerant | coolant used for the low-temperature refrigerating cycle 20 becomes higher in vapor density than a 1st refrigerant | coolant, and it becomes possible to improve the performance of the low-temperature refrigerating cycle 20 more.

  As an example, it is easily realized by using isobutane (boiling point −12 ° C.) as the first refrigerant and propane (boiling point −40.09 ° C.) or carbon dioxide (boiling point −78.5 ° C.) as the second refrigerant. be able to. All of these refrigerants are natural refrigerants that use substances that exist in large quantities in nature. Therefore, the environmental load of the refrigerator-freezer 1 can be further reduced by increasing the cooling efficiency of the refrigeration cycle using the natural refrigerant.

  In addition, although the Example demonstrated the freezer compartment 4 and the refrigerator compartment 2, instead of the freezer compartment 4 and the combination with the vegetable compartment etc. which were provided separately from the refrigerator compartment 2, the freezer compartment 4 and the refrigerator compartment 2 It may be combined with a vegetable room or the like.

  Further, the first evaporator 14 and the second evaporator 24 are disposed in the first cooling chamber and the second cooling chamber, respectively, having different indoor temperatures, and the first refrigeration cycle (high temperature) is performed by the first compressor 11 and the second compressor 21. As long as it is a refrigerator that operates the refrigeration cycle (10) and the second refrigeration cycle (low temperature refrigeration cycle) 20, the present invention can be similarly applied to anything.

  In addition, about the glass tube heater used for the defrost heater 8, and the thermistor used for the temperature detection means, it is an example and you may use another thing suitably.

  The freezer compartment door open / close detecting means G1 detects the open / close state of the freezer compartment door 4a with a door switch or the like provided in the heat insulating box 3 in contact with the freezer compartment door 4a, and the control unit sends the detection signal to the freezer compartment door. Although the number of times of opening / closing 4a is counted, a freezer compartment door opening / closing number counter may be provided separately or integrally, and the signal may be input to the control unit.

  In the embodiment shown above, the case where the refrigerator-freezer and the operation method thereof according to the present invention are required at least has been described as an example, but the present invention is a cooling device that requires defrosting. Applicable if possible.

  Embodiment described above is an example in implementing this invention to the last, and this invention is not limited to them. Aspects obtained by appropriately combining known technical techniques with the technical means disclosed in the above-described embodiments are also included in the technical scope of the present invention.

  According to this invention, it can utilize for the refrigerator-freezer provided with the refrigerator compartment and the freezer compartment.

DESCRIPTION OF SYMBOLS 1 Refrigeration refrigerator 2 Refrigeration room 3 Heat insulation box 4 Freezing room 4a Freezing room door 5 Machine room 6 Control part 8 Defrost heater 9 Heat insulating material 10 1st freezing cycle (high temperature freezing cycle)
11 1st compressor 12 1st condenser 13 1st expansion device 14 1st evaporator 15 refrigerator compartment fan 20 2nd freezing cycle (low temperature freezing cycle)
21 2nd compressor 22 2nd condenser 23 2nd expansion device 24 2nd evaporator 25 Freezer compartment fan 30 Refrigerating cycle 31 Intermediate heat exchanger 32 Outer box board A First predetermined integration time B Second predetermined integration time E1 Compressor control means E2 Compressor integrated operation time calculation means F1 Refrigeration room blower control means F2 Freezer room blower control means G1 Freezer compartment door open / close detection means H1 Ambient humidity detection means T1 Ambient temperature detection means T2 Second evaporator temperature detection means T3 Freezer temperature detection means

Claims (5)

A refrigerator room for storing stored items in a refrigerator;
A freezer room for freezing and storing stored items;
A first compressor that operates a first refrigeration cycle through which the first refrigerant flows;
A first evaporator disposed in a low temperature part of the first refrigeration cycle for cooling the refrigerator compartment;
A second compressor that operates a second refrigeration cycle through which the second refrigerant flows;
A second evaporator disposed in the low temperature part of the second refrigeration cycle for cooling the freezer compartment;
A control unit;
A plurality of detection means for detecting the ambient temperature of the refrigerator-freezer, the temperature inside the freezer compartment, the ambient humidity of the refrigerator-freezer and the opening / closing of the freezer compartment door;
In the refrigerator-freezer comprising:
The controller is
The defrosting of the second evaporator is started by a combination of two defrosting methods, an indefinite time defrosting based on the plurality of detection means and a timed defrosting based on the accumulated operation time of the refrigerator-freezer. A refrigerator-freezer.   The number of times of opening and closing the freezer compartment door, the absolute humidity of the air flowing into the freezer compartment, the internal capacity of the freezer compartment, and the rate at which the air inside the freezer compartment and the air outside the freezer compartment are exchanged by opening and closing the freezer compartment door. 2. The refrigerator-freezer according to claim 1, wherein when the calculated predicted frost amount exceeds the set predicted frost amount, defrosting is performed at an indefinite time.   The refrigerator-freezer according to claim 1 or 2, wherein the second predetermined integration time is shorter than the first predetermined integration time.   The refrigerator-freezer according to any one of claims 1 to 3, wherein counting of the compressor integrated operation time is started immediately after completion of defrosting. Each time the freezer door is opened and closed, the opening time of the freezer door is detected, and when the open time is short, the rate of air exchange is small, and when the open time is long, the rate of air exchange is largely converted and predicted. The refrigeration refrigerator according to any one of claims 1 to 4, wherein the amount of frost formation is calculated.