JP2002277083A - refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To block the flow of refrigerant into an evaporator in a refrigerator having a plurality of evaporators having different evaporation temperatures and using a cooling cycle for cooling by switching the evaporators. An object of the present invention is to prevent a power loss and a decrease in durability, which are problems when the compressor is operated (pump-down) in a state where the refrigerant is recovered and the refrigerant is recovered. SOLUTION: The cooling of the freezing room 3 is preferentially performed under all conditions, and the freezing room 3 is compared with the evaporation temperature at the time of cooling the freezing room 2.
By using a control method in which the cooling cycle is switched after the evaporating temperature at the time of cooling becomes low and the pump is reduced only immediately before switching from the freezing compartment cooling cycle to the refrigerator compartment cooling cycle, the power consumption associated with the pump down is reduced. The problem of loss and reduced durability can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator having a cooling cycle for independently cooling a freezer compartment and a refrigerating compartment, thereby eliminating the shortage of refrigerant.

[0002]

2. Description of the Related Art At present, energy saving of refrigerating apparatuses such as refrigerators and refrigerators has been promoted from the viewpoint of prevention of global warming.
Conventionally, in refrigerators that cool at different temperatures, such as a freezer compartment and a refrigerator compartment, a single evaporator is cooled to a temperature lower than the freezer compartment temperature to exchange heat with the air in the refrigerator, and the temperature in the refrigerator is adjusted by the amount of heat exchange. Was controlled by. On the other hand, by operating the two evaporators at the freezing room temperature and the cold room temperature independently of the freezing room and the cold room evaporator, the cooling room cooling cycle with a relatively low compression ratio and high theoretical efficiency is achieved. Attempts have been made to achieve energy savings by using a computer.

For example, Japanese Patent Application Laid-Open No. 58-88559 discloses a refrigerator having a cooling cycle in which two evaporators are switched to alternately cool a refrigerator compartment and a freezer compartment. Further, Japanese Patent Application Laid-Open No. 2000-266443 proposes a method of recovering the refrigerant remaining in the evaporator immediately before switching between the two evaporators and solving the problem of the shortage of the circulating refrigerant. Hereinafter, features of a conventional refrigerator using a cooling cycle for alternately cooling a refrigerator compartment and a freezer compartment will be described with reference to the drawings.

FIG. 18 shows a cycle configuration of a conventional refrigerator. In FIG. 18, 1 is a refrigerator, 2 is a refrigerating room, 3 is a freezing room, 4 is a compressor whose capacity can be controlled, 5 is a condenser, 6 is a flow path switching valve, and 7 is a One expansion mechanism, 8 is a first evaporator installed in the refrigerator compartment 2, 9 is a first accumulator installed in the refrigerator compartment 2 installed in the refrigerator compartment 2, 10 is a freezer compartment 3 , A second evaporator installed in the freezing room 3, a second accumulator installed in the freezing room 3, and a downstream of the second accumulator 12. A check valve installed on the side, 14 is a refrigerator box that forms the refrigerator compartment 2 and the freezer compartment 3 and insulates the outside, and 15 is a machine in which the compressor 4, the condenser 5, and the flow path switching valve 6 are arranged. Room.

The operation of the conventional refrigerator configured as described above will be described below.

When the refrigerator compartment 2 is cooled, the flow path from the condenser 5 to the first expansion mechanism 7 is opened, and the second expansion mechanism 1 is opened.
The flow path switching valve 6 operates so that the flow path to 0 is closed. The gas refrigerant compressed by the compressor 4 is supplied to the condenser 5
, And is decompressed by the first expansion mechanism 7 and evaporated by the first evaporator 8. At this time, the air in the refrigerator compartment 2 circulated by the first blower fan 16 is removed by the first evaporator 8.
The inside of the refrigerator compartment 2 is cooled by heat exchange. First evaporator 8
The refrigerant evaporated in the step is separated from the remaining liquid refrigerant by the first accumulator 9, and the gas refrigerant returns to the compressor 4. Also,
Although the pressure in the second evaporator 11 installed in the freezing chamber 3 is lower than that in the first evaporator 8, the check valve 13 is closed, so that the gas refrigerant flowing back to the compressor 4 is the second refrigerant. Second evaporator 1
It does not stay in 1.

Similarly, when cooling the freezing compartment 3, the flow from the condenser 5 to the second expansion mechanism 10 is opened and the flow to the first expansion mechanism 7 is closed. The path switching valve 6 operates. Then, the gas refrigerant compressed by the compressor 4 is condensed and liquefied by the condenser 5 and decompressed by the second expansion mechanism 10.
It evaporates in the second evaporator 11. At this time, the air in the freezing room 3 circulated by the second blower fan 17 exchanges heat with the second evaporator 11 to cool the inside of the freezing room 3. The refrigerant evaporated in the second evaporator 11 is separated from the remaining liquid refrigerant in the second accumulator 12, and the gas refrigerant passes through the check valve 13 and returns to the compressor 4. Further, since the pressure in the first evaporator 8 installed in the refrigerator compartment 2 is higher than that in the second evaporator, the refrigerant staying in the first evaporator 8 evaporates and the compressor 4 To reflux.

In general, the temperature of the refrigerating compartment 2 is set at 0 to 5 ° C. and the temperature of the freezing compartment 3 is set at about −18 ° C., so that the evaporating temperature of the first evaporator 8 is about −10 ° C. Is controlled at about −30 ° C. As a result, when the refrigerating compartment 2 is cooled, an efficient operation with a high evaporating temperature becomes possible, and the power consumption of the refrigerator 1 can be reduced.

Further, as a method of solving the problem that the refrigerant is dead inside the evaporator when the cooling cycle is switched, pump down (hereinafter referred to as PD) has been proposed. Hereinafter, the problem that the refrigerant is stored dead and the PD as a method for solving the problem will be described.

When switching from cooling the freezer compartment 3 to cooling the refrigerator compartment 2, the first evaporator 8 has a higher evaporation temperature than the second evaporator 11. The liquid refrigerant retained in the second evaporator 11 and the second accumulator 12 remains retained during the cooling of the refrigerator compartment 2, and as a result, a problem occurs in which the amount of the circulating refrigerant is insufficient during the cooling of the refrigerator compartment 2. . Similarly, when the evaporation temperature of the second evaporator 11 becomes higher than the evaporation temperature of the first evaporator 8 when the power is turned on or when the load changes, the amount of the circulating refrigerant is insufficient during the cooling of the freezing compartment 3. Occurs.

Therefore, when switching the cooling cycle,
While closing the flow paths from the condenser 5 to the first evaporator 8 and from the condenser 5 to the second evaporator 11, the compressor 4 is operated to operate the first evaporator and the first accumulator 9, or A PD has been proposed, which is a method of collecting the refrigerant remaining in the second evaporator 11 and the second accumulator 12 in the condenser 5. Further, by performing PD, it is not necessary to fill an excessive refrigerant into the cooling cycle, and the amount of the refrigerant to be charged can be reduced in the cooling cycle using a flammable refrigerant such as a hydrocarbon, and the effect of improving safety is expected. .

FIG. 19 shows an example of a cooling cycle switching operation using a PD and a change in suction pressure of the compressor 4 at this time.
Shown in The operation shown in FIG. 19 is an operation state in the case where the load is relatively large, in which the cooling of the refrigerator compartment 2 and the cooling of the freezer compartment 3 are alternately performed while the compressor 4 is continuously operated at 100% output. . In the cooling mode of the refrigerating room 2, the refrigerating room side of the flow path switching valve 6 is opened, and while the air in the refrigerating room 2 is cooled by the first blower fan 16, the condenser 5 is cooled by the cooling fan 18.
Heat is radiated to the outside. At this time, the suction pressure of the compressor 4 is stabilized at a pressure corresponding to the evaporation temperature of the first evaporator 8. In the next PD mode, the refrigerating compartment side and the freezing compartment side of the flow path switching valve 6 are both closed, and the compressor 4 is operated. At this time, the liquid refrigerant staying in the first evaporator 8 and the first accumulator 9 is returned to the compressor 4 while evaporating, and the suction pressure of the compressor 4 is rapidly reduced. In the cooling mode of the freezing room 3, the freezing room side of the flow path switching valve 6 is opened, and while the air in the freezing room 3 is cooled by the second blower fan 17, the heat of the condenser 5 is externally cooled by the cooling fan 18. Dissipates heat to At this time, the suction pressure of the compressor 4 is stabilized at a pressure corresponding to the evaporation temperature of the second evaporator 11.
In the next PD mode, the refrigerating compartment side and the freezing compartment side of the flow path switching valve 6 are both closed, and the compressor 4 is operated. At this time,
The liquid refrigerant staying in the second evaporator 11 and the second accumulator 12 is returned to the compressor 4 while evaporating, and the suction pressure of the compressor 4 is rapidly reduced. By alternately cooling the refrigerating compartment 2 and the freezing compartment 3 while switching the operation mode in this manner, high-efficiency operation can be performed without causing a problem of insufficient amount of circulating refrigerant, and power consumption of the refrigerator 1 can be reduced.

[0013]

However, in the above-described conventional configuration, the effect of reducing the power consumption is not only offset by the loss of the compressor 4 due to the PD operation, but also the suction pressure of the compressor 4 during the PD operation. Was abnormally lowered beyond the allowable range, and durability could not be maintained.

Therefore, there is a demand for a measure for suppressing the time of the PD operation and fundamentally avoiding an abnormal decrease in the suction pressure during the PD operation.

The present invention examines in detail the amount of refrigerant stored at the time of switching the cooling cycle and the refrigerant recovery behavior during the PD operation, and clarifies the relationship between the evaporator configuration and the suction pressure to improve the PD operation. The purpose of the present invention is to solve the problems of power loss and durability deterioration due to the PD operation.

[0016]

Therefore, in the refrigerator of the present invention, cooling of the freezer compartment is prioritized under all conditions, and the evaporation temperature of the freezer compartment is lower than that of the refrigerator compartment. A control method is used in which the cooling cycle is switched after the state is reached, and the PD operation is performed only immediately before switching from the freezing compartment cooling cycle to the refrigerator compartment cooling cycle.

According to the present invention, the PD operation at the time of switching from the refrigerator compartment cooling cycle to the freezer compartment cooling cycle can be omitted, and the problems of power loss and reduced durability due to the PD operation can be reduced.

Further, the refrigerator of the present invention uses a control method in which an accumulator is not installed in a freezer compartment and a refrigerator compartment, and a cooling cycle is switched without PD operation.

According to the present invention, the PD operation at the time of switching the cooling cycle can be omitted by reducing the amount of refrigerant to be stored, and the problems of power loss and durability reduction accompanying the PD operation can be solved.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a refrigerator having a refrigerator compartment and a freezer compartment, comprising a compressor, a condenser, a flow path switching valve, and a first expansion. A mechanism, a first evaporator installed in the refrigerator compartment, a first accumulator installed in the refrigerator compartment, a second expansion mechanism, and a second evaporator installed in the freezer compartment. And a second accumulator installed in the freezer compartment,
A closed loop is formed by the compressor, the condenser, the flow path switching valve, the first expansion mechanism, the first evaporator, and the first accumulator, and the first expansion mechanism and the first Connect the second expansion mechanism, the second evaporator, the second accumulator and the check valve so as to be in parallel with one evaporator and the first accumulator,
The refrigerating compartment and the freezing compartment are cooled independently of each other by switching the flow of the refrigerant by the flow path switching valve, and the cooling of the freezing compartment is prioritized, and the cooling of the freezing compartment is performed from the cooling of the freezing compartment. Just before switching to room cooling,
Control means for operating the compressor (ie, PD operation) in a state where the flow of the refrigerant into the second evaporator is shut off using the flow path switching valve or the second expansion mechanism. And

With the above configuration, cooling of the freezer compartment is prioritized under all conditions, and cooling is performed after the evaporating temperature of the freezing compartment becomes lower than that of the refrigerating compartment. By performing the cycle switching, the PD operation when switching from the refrigerator compartment cooling cycle to the freezer compartment cooling cycle is omitted, and the PD operation is performed only when switching from the freezer compartment cooling cycle to the refrigerator compartment cooling cycle.
It is possible to reduce power loss and durability problems associated with the D operation.

According to a second aspect of the present invention, there is provided a blower fan for promoting heat exchange between air in the freezer compartment and the second evaporator, and immediately before switching from cooling of the freezer compartment to cooling of the refrigerator compartment. 2. The control device according to claim 1, further comprising control means for operating the compressor (i.e., PD operation) while operating the blower fan in a state where the flow of the refrigerant into the second evaporator is shut off. In a refrigerator, by heating the second evaporator with air in the freezer compartment, by suppressing the temperature drop when collecting the staying liquid refrigerant, and by suppressing the drop in suction pressure during PD operation, Further, the problem of power loss and deterioration of durability due to the PD operation can be reduced.

Since the inside of the second evaporator is a gas-liquid two-phase flow, the amount of liquid refrigerant retained in the second evaporator is smaller than the amount retained in the second accumulator, and During the fan operation, the liquid refrigerant staying in the second evaporator evaporates preferentially, so it is not necessary to always operate the blower fan during the PD operation, and operate the blower fan for a predetermined time at the beginning of the PD operation. Just do it.

[0024] The invention according to claim 3 of the present invention is provided with a heater disposed on the surface of the second accumulator, and immediately before switching from the cooling of the freezing room to the cooling of the refrigerating room, the heater is connected to the second evaporator. The refrigerator according to any one of claims 1 to 2, further comprising control means for operating the compressor (i.e., PD operation) while energizing the heater while the flow of the refrigerant is shut off. By heating the second accumulator with a heater, the temperature drop when recovering the staying liquid refrigerant is suppressed, and the suction pressure drop during the PD operation is suppressed, thereby further reducing the power loss accompanying the PD operation. And the problem of reduced durability can be reduced.

Since the inside of the second evaporator is a gas-liquid two-phase flow, the amount of liquid refrigerant retained in the second accumulator is much larger than the amount retained in the second evaporator. It is important to heat the second accumulator. In addition, in order to reduce the loss caused by heating the freezing compartment, it is preferable to attach a surface heater or the like to the surface of the second accumulator and directly heat the second accumulator.

It should be noted that, even if the second accumulator is heated for a long time before the PD operation, the effect of reducing the amount of liquid refrigerant retained in the second accumulator is small only by being offset by the cooling operation. In order to reduce the time lag until the temperature rise, it is desirable to turn on the heater a predetermined time before the PD operation.

According to a fourth aspect of the present invention, a compressor having a variable capacity type is provided, and the flow of refrigerant into the second evaporator is interrupted immediately before switching from cooling of the freezing compartment to cooling of the refrigerator compartment. With the compressor operating at low capacity (ie, PD operation)
The refrigerator according to any one of claims 1 to 3, further comprising a control unit that performs evaporation by evaporating at a speed commensurate with the amount of heat transferred to the staying liquid refrigerant. By suppressing the temperature drop when recovering the liquid refrigerant and the drop in the suction pressure during the PD operation, it is possible to further reduce the problems of power loss and reduced durability associated with the PD operation.

Here, when the PD operation is performed in a low-capacity operation, the refrigerant recovery speed is reduced and the PD operation time for recovering the required amount of refrigerant is prolonged. However, since the reduction in the suction pressure can be suppressed, the required time during the PD operation is reduced. Power can be reduced. However, under high load conditions, since the bearing load increases almost in proportion to the condensing pressure, it may be difficult to reduce the capacity by low-speed rotation, which is inferior in bearing load resistance. In this case, it is desirable to realize a low capacity at a low speed rotation at a limit where durability can be guaranteed.

[0029] The invention according to claim 5 of the present invention is characterized in that the flow of the refrigerant to the second evaporator is shut off immediately before switching from the cooling of the freezing compartment to the cooling of the refrigerating compartment. Operate the compressor using the first expansion mechanism while allowing a small amount of refrigerant to flow into the first evaporator (ie, PD operation)
The refrigerator according to any one of claims 1 to 4, further comprising: a control unit configured to evaporate at a speed commensurate with the amount of heat transferred to the staying liquid refrigerant. By suppressing the temperature drop when recovering the liquid refrigerant and the drop in the suction pressure during the PD operation, it is possible to further reduce the problems of power loss and reduced durability associated with the PD operation.

Here, the flow of the refrigerant from the refrigerating compartment cooling cycle lowers the refrigerant recovery speed, so that the PD operation time for recovering the required amount of refrigerant becomes longer. However, since the reduction of the suction pressure can be suppressed, the PD operation is stopped. The required power requirements can be reduced. In addition, this method has no restrictions as compared with the reduction of the refrigerant recovery speed due to the reduction in capacity of the compressor, and the refrigerant recovery speed can be freely set to a speed commensurate with the amount of heat transferred to the staying liquid refrigerant. In addition, since the refrigerant flowing from the refrigerator compartment cooling cycle during the PD operation contributes to the cooling of the first evaporator, the effect that the rise of the refrigerator compartment cooling cycle is accelerated can be expected.

According to a sixth aspect of the present invention, there is provided a cooling fan for cooling the compressor or the condenser, and the refrigerant is supplied to the second evaporator immediately before switching from cooling the freezing compartment to cooling the refrigerator compartment. 6. A control means for operating the compressor (ie, the PD operation) while operating the cooling fan in a state where the inflow of air is blocked.
In the refrigerator according to any one of the above, by reducing the condensing pressure at the time of the PD operation, it is possible to further reduce the problem of power loss and reduced durability associated with the PD operation.

[0032] The invention according to claim 7 of the present invention is provided with detecting means for detecting the temperature or pressure of the refrigerant stagnating in the second accumulator, and immediately before switching from cooling of the freezing compartment to cooling of the refrigerator compartment, the detecting means is provided. Control means for operating the compressor (ie, PD operation) until the temperature or pressure of the refrigerant obtained by the detection means falls below a predetermined value while the flow of the refrigerant into the second evaporator is blocked. The refrigerator according to any one of claims 1 to 6, wherein a PD operation at an abnormally low suction pressure is prevented to further reduce power loss and durability due to the PD operation. Problem can be reduced.

[0033] The invention according to claim 8 of the present invention is a refrigerator having a refrigerator compartment and a freezer compartment, comprising: a compressor, a condenser, a flow path switching valve, a first expansion mechanism, A first evaporator installed in the refrigerator compartment, a second expansion mechanism, a second evaporator installed in the freezer compartment, the compressor, the condenser, the flow switching valve, and the second evaporator. A second expansion mechanism and the second evaporator so as to form a closed loop with one expansion mechanism and the first evaporator, and to be in parallel with the first expansion mechanism and the first evaporator; And the check valve,
The refrigerating compartment and the freezing compartment are independently cooled by switching the flow of the refrigerant by the flow path switching valve, and no accumulator is provided in the freezing compartment and the refrigerating compartment, and the freezing compartment is not provided. Control means for operating the compressor for a predetermined period of time (ie, PD operation) in a state in which the flow of the refrigerant into the second evaporator is shut off immediately before switching from cooling of the refrigerator to cooling of the refrigerator compartment. A refrigerator that does not have an accumulator in which a large amount of liquid refrigerant is stored and operates for a predetermined period of time in PD, so that heat is relatively easily transferred and the temperature of the refrigerant in the second evaporator is small with a decrease in temperature. By recovering almost all of the
The problems of power loss and reduced durability associated with the operation can be almost eliminated.

Here, when the accumulator is installed only in the refrigerator compartment, the suction pressure is lower than the evaporation pressure corresponding to the refrigerator compartment temperature during the cooling of the refrigerator compartment, and the liquid refrigerant in the accumulator of the refrigerator compartment is recovered by the compressor. However, since the accumulator during cooling of the refrigerator compartment is almost full, the amount of circulating refrigerant tends to be insufficient during cooling of the refrigerator compartment. Therefore, it is desirable not to install an accumulator in both the freezer compartment and the refrigerator compartment. Similarly, when the accumulator is not installed in both the freezing room and the refrigerator compartment, the amount of refrigerant charged can be reduced by the amount of the refrigerant that is dead when the accumulator is installed. Is also expected to improve the effect.

Further, since the inside of the second evaporator is a gas-liquid two-phase flow, the amount of liquid refrigerant retained in the accumulator when the accumulator is installed is much larger than the amount retained in the second evaporator. Therefore, the PD time for recovering almost all of the accumulated refrigerant is 3 hours when the accumulator is installed.
While it takes about 10 to 10 minutes, it can be reduced to several tens of seconds or about 1/10 without an accumulator. As a result, the problems of power loss and reduced durability associated with the PD operation can be almost eliminated.

When almost all of the refrigerant remaining in the second evaporator is recovered by the PD operation, since the second evaporator easily conducts heat with the air in the freezing chamber, the temperature of the liquid refrigerant being recovered decreases. Although it is relatively easy to maintain the suction pressure, it is preferable that the second evaporator uses a blower fan to promote the heat transfer of the air in the freezer compartment. When a blower fan is used, the PD operation can be performed with little increase in the compression ratio.

According to a ninth aspect of the present invention, there is provided a refrigerator having a refrigerator compartment and a freezer compartment, comprising a compressor, a condenser, a flow path switching valve, a first expansion mechanism, A first evaporator installed in the refrigerator compartment, a second expansion mechanism, a second evaporator installed in the freezer compartment, the compressor, the condenser, the flow switching valve, and the second evaporator. A second expansion mechanism and the second evaporator so as to form a closed loop with one expansion mechanism and the first evaporator, and to be in parallel with the first expansion mechanism and the first evaporator; And the check valve,
The refrigerating compartment and the freezing compartment are cooled independently of each other by switching the flow of the refrigerant by the flow passage switching valve, and no accumulator is installed in the freezing compartment and the refrigerating compartment, and the first A control means for operating the compressor (that is, PD operation) in a state where the inflow of the refrigerant into the evaporator and the second evaporator is shut off, wherein a large amount of liquid refrigerant is used. By not installing a dead accumulator and not performing the PD operation, it is possible to solve the problems of power loss and reduced durability due to the PD operation.

Here, when the accumulator is installed only in the refrigerator compartment, the suction pressure is lower than the evaporation pressure corresponding to the refrigerator compartment temperature during the cooling of the freezer compartment, and the liquid refrigerant in the accumulator of the refrigerator compartment is recovered by the compressor. However, since the accumulator during cooling of the refrigerator compartment is almost full, the amount of circulating refrigerant tends to be insufficient during cooling of the refrigerator compartment. Therefore, it is desirable not to install an accumulator in both the freezer compartment and the refrigerator compartment. Similarly, when the accumulator is not installed in both the freezer compartment and the refrigerator compartment, the amount of refrigerant charged can be reduced by the amount of the refrigerant that is refrigerated when the accumulator is installed, so that the safety in the cooling cycle using flammable refrigerants such as hydrocarbons is further improved. Is also expected to improve the effect.

Further, since the inside of the second evaporator is a gas-liquid two-phase flow, the amount of liquid refrigerant retained in the second evaporator is smaller than the amount of liquid refrigerant retained in the accumulator when the accumulator is installed. Much less. Therefore, if the allowable range of the amount of the filled refrigerant is increased by, for example, installing a small-capacity liquid receiver at the condenser outlet, the refrigerating chamber cooling cycle can be performed while a small amount of the liquid refrigerant remains in the second evaporator. Does not cause a shortage of the circulating refrigerant.

According to a tenth aspect of the present invention, there is provided a control means for reducing the flow path resistance of the second expansion mechanism when the power is turned on, as compared with the normal operation.
Or the refrigerator according to item 9, wherein an accumulator in which a large amount of liquid refrigerant is stored is not installed.
It is possible to solve the problems of power loss and durability deterioration associated with the D operation, and to shorten the pull-down time by increasing the flow rate of the refrigerant at the time of turning on the power.

When an accumulator is installed at the outlet of the evaporator, the amount of refrigerant staying in the accumulator hardly changes during steady-state operation and remains in a dead state. At the time of charging or overload, the amount of refrigerant circulating through the cooling cycle decreases and increases. As a result, at the time of power-on or overload, the flow rate of the refrigerant increases, and the cooling cycle can have a higher capacity. However, when an accumulator is not installed, this effect does not occur, and the cooling cycle capacity is insufficient when the power is turned on, which tends to increase the pull-down time. The room temperature tends to increase slightly.

Therefore, by switching the second expansion mechanism, which has a relatively large flow path resistance and is likely to cause a shortage of the refrigerant flow when the power is turned on, so that the flow resistance becomes smaller than at the time of the normal operation at the time of power supply, the second expansion mechanism is switched at the time of power supply. The pull-down time can be shortened by increasing the refrigerant flow rate in the cooling cycle. Similarly, even during overload when the temperature of the freezer compartment or the refrigerator compartment becomes higher, the flow rate is switched so as to make the flow path resistance smaller than at the time of steady operation, thereby increasing the refrigerant flow rate of the cooling cycle and increasing the temperature of the freezer compartment or the refrigerator compartment. The effect of suppressing the rise can be expected.

According to an eleventh aspect of the present invention, the first evaporator and the second evaporator have excessive capacity, and superheat is maintained during a steady operation. The refrigerator according to any one of claims 1 to 10, wherein the problem of power loss and durability deterioration due to PD operation can be solved by not installing an accumulator in which a large amount of liquid refrigerant is stored. At the same time, liquid back to the suction pipe can be prevented.

Here, when an accumulator is installed at the evaporator outlet, when the capacity of the first evaporator or the second evaporator is insufficient with respect to the refrigerant flow rate, the liquid refrigerant that cannot be completely evaporated by the evaporator is removed. Temporarily stays in the accumulator. As a result, liquid back to the suction pipe can be prevented. However, when the accumulator is not installed, this function is not provided, and liquid backs to the suction pipe, and the suction pipe tends to be exposed due to a decrease in temperature, and the durability of the compressor may be reduced.

Therefore, by increasing the capacity of the first evaporator and the second evaporator so as to maintain the superheat during the steady operation, it is possible to prevent the liquid from flowing back into the suction pipe.

According to a twelfth aspect of the present invention, in the refrigerator according to any one of the eighth to eleventh aspects, an accumulator is provided near the compressor. By not installing an accumulator in which a large amount is stored, it is possible to solve the problems of power loss and reduced durability due to the PD operation, and also to prevent liquid back into the suction pipe.

Here, when an accumulator is installed at the evaporator outlet, when the capacity of the first evaporator or the second evaporator is insufficient with respect to the refrigerant flow rate, the liquid refrigerant that cannot be completely evaporated by the evaporator is removed. Temporarily stays in the accumulator. As a result, liquid back to the suction pipe can be prevented. However, when the accumulator is not installed, this function is not provided, and liquid backs to the suction pipe, and the suction pipe tends to be exposed due to a decrease in temperature, and the durability of the compressor may be reduced.

Therefore, by installing an accumulator near the compressor, the liquid refrigerant that has been recirculated together with the suction gas can be temporarily retained in the accumulator near the compressor, and liquid back to the suction pipe can be prevented.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. In these figures, FIG.
8, the same configuration and operation as those of the conventional example shown in FIG. 19 will not be described in detail, and will be denoted by the same reference numerals.

(Embodiment 1) FIG. 1 is a refrigeration cycle diagram of a refrigerator showing an embodiment of the present invention, and FIG. 2 is a timing chart showing the operation and suction pressure change in the embodiment.

The cycle configuration of the refrigerator in the present embodiment is the same as that of the conventional example shown in FIG. The feature of the operation in the present embodiment is that the cooling of the freezer compartment 3 is given priority over the cooling of the refrigerator compartment 2, and the freezing is always performed while the air temperature in the freezer compartment 3 is higher than that in the refrigerator compartment 2. Only the chamber 3 is cooled, and the PD operation is performed only when switching from the cooling of the freezing chamber 3 to the cooling of the refrigerator compartment 2 as shown in FIG.

As a result, when the cooling of the refrigerator compartment 2 is switched to the cooling of the freezer compartment 3, the liquid refrigerant retained in the first evaporator 8 and the first accumulator 9 installed in the refrigerator compartment 2 is evaporated. During the cooling of the freezing room 3 having a low temperature, the refrigerant evaporates and is collected by the compressor 4 and is returned to the cooling cycle to secure the amount of the circulating refrigerant. Accordingly, the problem of the input loss of the compressor 4 and the decrease in durability due to the decrease in suction pressure can be reduced.

In the present embodiment, the flow path from the condenser 5 is switched using the flow path switching valve 6, but the first expansion mechanism 7 and the second expansion mechanism 10 have closing mechanisms. If it does, the flow path can be switched without using the flow path switching valve 6. Further, the flow path resistance of the first expansion mechanism 7 and the second expansion mechanism 10 may be a constant resistance such as a capillary, or may be a variable resistance such as an expansion valve.

(Embodiment 2) FIG. 3 is a timing chart showing a driving operation and a change in suction pressure according to an embodiment of the present invention.

The cycle configuration of the refrigerator in the present embodiment is the same as that in the first embodiment.

The features of the driving operation in this embodiment are as follows.
Prioritizing the cooling of the freezer compartment 3 over the cooling of the refrigerator compartment 2, while the air temperature in the freezer compartment 3 is higher than that in the refrigerator compartment 2, only the freezer compartment 3 is always cooled, and FIG. As shown, the PD operation is performed only when switching from the cooling of the freezer compartment 3 to the cooling of the refrigerator compartment 2. Further, as shown in FIG. 3, the second blower fan 17 is operated during the PD operation.

As a result, when the cooling of the refrigerator compartment 2 is switched to the cooling of the freezer compartment 3, the liquid refrigerant retained in the first evaporator 8 and the first accumulator 9 installed in the refrigerator compartment 2 is evaporated. During the cooling of the freezing room 3 having a low temperature, the refrigerant evaporates and is collected by the compressor 4 and is returned to the cooling cycle to secure the amount of the circulating refrigerant. Accordingly, the problem of the input loss of the compressor 4 and the decrease in durability due to the decrease in suction pressure can be reduced.
Further, by operating the second blower fan 17 during the PD operation, the second evaporator 11 is heated by the air in the freezing room 3 and the liquid refrigerant remaining in the second evaporator 11 evaporates. In this case, a decrease in the temperature of the liquid refrigerant at the time can be suppressed, and a decrease in the suction pressure during the PD operation can be suppressed as shown in FIG.

Here, the point A in FIG. 3 is a point in time when all the liquid refrigerant staying in the second evaporator 11 evaporates, and indicates that a decrease in the suction pressure can be suppressed up to this point.

After the point A in FIG. 3, the liquid refrigerant remaining in the second accumulator 12 starts to evaporate, the temperature of the liquid refrigerant decreases, and the suction pressure decreases.
The D operation ends. This is the second accumulator 1
2 is designed for storing a liquid refrigerant,
This is because the heat exchange efficiency of the air inside is low, and the temperature of the liquid refrigerant staying in the second accumulator 12 cannot be prevented from decreasing only by operating the second blower fan 17. However, during the period from the start of PD to the point A, as a result of evaporating the liquid refrigerant mainly retained in the second evaporator 11, the liquid retained in the second accumulator 12 is smaller than when the second blower fan 17 is stopped. Evaporation and temperature drop of the refrigerant are suppressed.

In order to suppress the amount of heat generated by the operation of the second blower fan 17, it is desirable to stop the second blower fan 17 at the point A in FIG. Operating the second blower fan 17 between the points A and B has almost no effect of evaporating the liquid refrigerant remaining in the second accumulator 12 and also generates heat due to the operation of the second blower fan 17. The problem that the air temperature in the freezer compartment 3 rises depending on the amount occurs.

(Embodiment 3) FIG. 4 is a refrigeration cycle diagram of a refrigerator showing an embodiment of the present invention, and FIG. 5 is a timing chart showing the operation and suction pressure change in the embodiment. A feature of the cycle configuration of the refrigerator in the present embodiment is that an accumulator heater 19 is provided on the surface of the second accumulator 12 to directly heat the second accumulator 12.

The features of the driving operation in this embodiment are as follows.
The cooling of the freezer compartment 3 is prioritized over the cooling of the refrigerator compartment 2, and while the air temperature in the freezer compartment 3 is higher than that in the refrigerator compartment 2, only the freezer compartment 3 is always cooled. As shown, the PD operation is performed only when switching from the cooling of the freezer compartment 3 to the cooling of the refrigerator compartment 2. Further, as shown in FIG. 5, the accumulation heater 19 is turned ON only during the PD operation.

As a result, when the cooling of the refrigerator compartment 2 is switched to the cooling of the freezer compartment 3, the liquid refrigerant retained in the first evaporator 8 or the first accumulator 9 installed in the refrigerator compartment 2 is evaporated. During the cooling of the freezing room 3 having a low temperature, the refrigerant evaporates and is collected by the compressor 4 and is returned to the cooling cycle to secure the amount of the circulating refrigerant. Accordingly, the problem of the input loss of the compressor 4 and the decrease in durability due to the decrease in suction pressure can be reduced.
Further, by turning on the accumulator heater 19 during the PD operation, the second accumulator 12 is directly heated to suppress a decrease in the temperature of the liquid refrigerant when the liquid refrigerant remaining in the second accumulator 12 evaporates. Can be
As shown in FIG. 5, a decrease in suction pressure during PD operation can be suppressed.

Here, the point C in FIG. 5 is a point where a part of the liquid refrigerant staying in the second accumulator 12 evaporates and the PD operation ends, and the accumulator 19 is turned off.
As compared with the case where the same amount of the liquid refrigerant is evaporated as it is, the evaporation and the temperature decrease of the liquid refrigerant remaining in the second accumulator 12 are suppressed.

Although a similar effect can be expected by using a defrosting heater (not shown) normally installed near the second evaporator 11 in place of the accumulator heater 19, the structure is freezer compartment. Indirect heating of the second accumulator 12, which has a poor heat exchange efficiency with the air in the refrigerator 3, causes a problem in that the temperature of the air in the freezer 3 rises. It is preferable to use a means for heating the water.

(Embodiment 4) FIG. 6 is a timing chart showing a driving operation and a change in suction pressure according to an embodiment of the present invention. The cycle configuration of the refrigerator in the present embodiment is the same as that in the first embodiment.

The features of the driving operation in this embodiment are as follows.
The cooling of the freezer compartment 3 is prioritized over the cooling of the refrigerator compartment 2, and while the air temperature in the freezer compartment 3 is higher than that in the refrigerator compartment 2, only the freezer compartment 3 is always cooled, and FIG. As shown, the PD operation is performed only when switching from the cooling of the freezer compartment 3 to the cooling of the refrigerator compartment 2. Further, as shown in FIG. 6, the output of the compressor 4 is reduced to 40% during the PD operation.

As a result, when the cooling of the refrigerator compartment 2 is switched to the cooling of the freezer compartment 3, the liquid refrigerant retained in the first evaporator 8 and the first accumulator 9 installed in the refrigerator compartment 2 is evaporated. During the cooling of the low-temperature freezing chamber 3, the refrigerant evaporates and is collected by the compressor 4, and is returned to the cooling cycle to secure the amount of circulating refrigerant. Thus, the problem of the input loss of the compressor 4 and the decrease of the durability due to the decrease of the suction pressure can be reduced. Further, by reducing the output of the compressor 4 during the PD operation to 40%, the speed at which the liquid refrigerant staying in the second evaporator 11 and the second accumulator 12 evaporates is reduced, and as a result, the liquid A decrease in the temperature of the refrigerant can be suppressed, and a decrease in the suction pressure during the PD operation can be suppressed as shown in FIG.

Here, the temperature change of the liquid refrigerant staying in the second evaporator 11 and the second accumulator 12 is as follows.
It is determined by the balance between the latent heat of evaporation lost by evaporation and the heat supplied by the air in the freezer compartment 3 or the heat conduction from the components, so that the temperature at which the liquid refrigerant evaporates is reduced by reducing the speed at which the liquid refrigerant evaporates. You can do it. The point D in FIG. 6 is a point where a part of the liquid refrigerant staying in the second evaporator 11 and the second accumulator 12 evaporates and the PD operation is completed.
Compared to the case where the same amount of liquid refrigerant was evaporated at 0%,
Evaporation and temperature decrease of the liquid refrigerant staying in the second evaporator 11 and the second accumulator 12 are suppressed.

In this embodiment, the output of the compressor 4 during the PD operation is set to 40%. However, in the case of a rotary compressor or a reciprocating compressor generally used in a household refrigerator, the rotation speed of the compressor is The same effect can be expected even if the output is reduced and the output is arbitrarily suppressed.

At this time, the evaporation speed of the liquid refrigerant staying in the second evaporator 11 and the second accumulator 12 is set to 5
By controlling the temperature to about g / 10 s or less, a decrease in the temperature of the staying refrigerant can be considerably suppressed. Further, when the temperature is increased by the method described in Embodiments 2 and 3 together with the reduction of the evaporation rate of the staying refrigerant, the temperature of the staying refrigerant is expected to be more stable.

(Embodiment 5) FIG. 7 is a timing chart showing a driving operation and a change in suction pressure according to an embodiment of the present invention.

The cycle configuration of the refrigerator according to the present embodiment is the same as that of the first embodiment.

The features of the driving operation in this embodiment are as follows.
The cooling of the freezer compartment 3 is prioritized over the cooling of the refrigerator compartment 2, and while the air temperature in the freezer compartment 3 is higher than that in the refrigerator compartment 2, only the freezer compartment 3 is always cooled, and FIG. As shown, the PD operation is performed only when switching from the cooling of the freezer compartment 3 to the cooling of the refrigerator compartment 2. Further, as shown in FIG. 7, during the PD operation, the first expansion mechanism 7 is opened by 30% and the flow path on the refrigeration side of the flow path switching valve 6 is opened.

As a result, when the cooling of the refrigerator compartment 2 is switched to the cooling of the freezer compartment 3, the liquid refrigerant retained in the first evaporator 8 and the first accumulator 9 installed in the refrigerator compartment 2 is evaporated. During the cooling of the freezing room 3 having a low temperature, the refrigerant evaporates and is collected by the compressor 4 and is returned to the cooling cycle to secure the amount of the circulating refrigerant. Accordingly, the problem of the input loss of the compressor 4 and the decrease in durability due to the decrease in suction pressure can be reduced.
Further, by opening the first expansion mechanism 7 by 30% during the PD operation and opening the refrigerating side flow path of the flow path switching valve 6 to supply a small amount of refrigerant to the cooling cycle of the refrigerating chamber 2, Second evaporator 11 and second accumulator 12
The rate at which the liquid refrigerant staying inside evaporates is reduced, and as a result, a decrease in the temperature of the liquid refrigerant can be suppressed. As shown in FIG. 7, a decrease in the suction pressure during the PD operation can be suppressed.

Here, the temperature change of the liquid refrigerant staying in the second evaporator 11 and the second accumulator 12 is as follows.
It is determined by the balance between the latent heat of evaporation lost by evaporation and the heat supplied by the air in the freezer compartment 3 or the heat conduction from the components, so that the temperature at which the liquid refrigerant evaporates is reduced by reducing the speed at which the liquid refrigerant evaporates. You can do it. Point E in FIG. 7 is a point at which a part of the liquid refrigerant remaining in the second evaporator 11 and the second accumulator 12 evaporates and the PD operation ends, and the cooling cycle of the refrigerator compartment 2 is closed. As compared with the case where the same amount of liquid refrigerant is evaporated, the second evaporator 11 and the second accumulator 12
Evaporation and temperature decrease of the liquid refrigerant staying in the tank are suppressed.

In the present embodiment, the opening degree of the first expansion mechanism 7 during the PD operation is set to 30%. However, the evaporating temperature of the refrigerating compartment 2 when the cooling cycle is operated alone is lower than the air temperature of the freezing compartment 3. If the opening degree of the first expansion mechanism 7 is adjusted to be a low temperature, the evaporation rate of the liquid refrigerant remaining in the second evaporator 11 and the second accumulator 12 can be suppressed while maintaining the evaporation rate. The same effect can be expected. At this time, if the evaporation rate of the liquid refrigerant staying in the second evaporator 11 and the second accumulator 12 is controlled to about 5 g / 10 s or less, the temperature drop of the staying refrigerant can be considerably suppressed. Further, when the temperature is increased by the method described in Embodiments 2 and 3 together with the reduction of the evaporation rate of the staying refrigerant, the temperature of the staying refrigerant is expected to be more stable.

In the present embodiment, the first expansion mechanism 7 is desirably a variable resistor such as an expansion valve. However, in order to flow a small amount of refrigerant during the PD operation, the opening and closing operation is repeated to control the flow rate. Alternatively, the flow rate may be controlled by switching to a capillary having a large resistance for the PD operation.

(Embodiment 6) FIG. 8 is a timing chart showing a driving operation and a change in suction pressure according to an embodiment of the present invention.

The cycle configuration of the refrigerator according to the present embodiment is the same as that of the first embodiment.

The features of the driving operation in this embodiment are as follows.
The cooling of the freezer compartment 3 is prioritized over the cooling of the refrigerator compartment 2, and while the air temperature in the freezer compartment 3 is higher than that in the refrigerator compartment 2, only the freezer compartment 3 is always cooled, and FIG. As shown, the PD operation is performed only when switching from the cooling of the freezer compartment 3 to the cooling of the refrigerator compartment 2. Further, as shown in FIG. 8, the cooling fan 18 is operated during the PD operation.

As a result, when the cooling of the refrigerator compartment 2 is switched to the cooling of the freezer compartment 3, the liquid refrigerant retained in the first evaporator 8 and the first accumulator 9 installed in the refrigerator compartment 2 is evaporated. During the cooling of the freezing room 3 having a low temperature, the refrigerant evaporates and is collected by the compressor 4 and is returned to the cooling cycle to secure the amount of the circulating refrigerant. Accordingly, the problem of the input loss of the compressor 4 and the decrease in durability due to the decrease in suction pressure can be reduced.
Further, by operating the cooling fan 18 during the PD operation, heat exchange of the condenser 5 is promoted to reduce the condensation temperature, and as a result, the compression ratio during the PD operation can be reduced. In addition to reducing the condensation temperature, the second embodiment
When the reduction of the suction pressure is suppressed by the methods described in Nos. To 5, it is expected that the compression ratio will be lower and stable.

The increase in the power loss due to the decrease in the suction pressure becomes significant in proportion to the compression ratio because of the compression of the re-expansion gas. It is desirable to set an upper limit on the compression ratio during the PD operation, because the change becomes noticeable at a specific compression ratio or higher due to the change. In general reciprocating compressors for refrigerators, the upper limit of the compression ratio during PD operation is about 15 to 20. Exceeding this compression ratio causes a significant decrease in efficiency, a rise in discharge gas temperature and an increase in the size of the bearing. Abrasion occurs and the problem of reduced durability occurs.

(Embodiment 7) FIG. 9 is a refrigeration cycle diagram of a refrigerator showing an embodiment of the present invention, and FIG. 10 is a timing chart showing the operation and suction pressure change in the embodiment. A feature of the cycle configuration of the refrigerator in the present embodiment is that a temperature detector 20 for detecting the temperature of the second accumulator 12 is provided.

The features of the exercise operation in the present embodiment are as follows.
The cooling of the freezer compartment 3 is prioritized over the cooling of the refrigerator compartment 2, and while the air temperature in the freezer compartment 3 is higher than that in the refrigerator compartment 2, only the freezer compartment 3 is always cooled, and FIG. As shown, the PD operation is performed only when switching from the cooling of the freezer compartment 3 to the cooling of the refrigerator compartment 2. Further, as shown in FIG. 10, when the temperature detector 20 becomes lower than a predetermined value during the PD operation, the PD operation is stopped, and the mode shifts to the refrigerator compartment cooling mode.

As a result, when the cooling of the refrigerator compartment 2 is switched to the cooling of the freezing compartment 3, the liquid refrigerant retained in the first evaporator 8 and the first accumulator 9 installed in the cooling compartment 2 is evaporated. During the cooling of the freezing room 3 having a low temperature, the refrigerant evaporates and is collected by the compressor 4 and is returned to the cooling cycle to secure the amount of the circulating refrigerant. Accordingly, the problem of the input loss of the compressor 4 and the decrease in durability due to the decrease in suction pressure can be reduced.
Further, when the temperature of the liquid refrigerant staying in the second accumulator 12 decreases and the surface temperature of the second accumulator 12 decreases, the temperature detector 20 detects the temperature and stops the PD operation. The problem of the input loss of the compressor 4 due to the PD operation and the decrease in durability due to the decrease in the suction pressure can be reduced.

The increase in the power loss due to the decrease in the suction pressure becomes significant in proportion to the compression ratio because of the compression of the re-expansion gas. It is desirable to set an upper limit on the compression ratio during the PD operation, because the change becomes noticeable at a specific compression ratio or higher due to the change. In general reciprocating compressors for refrigerators, the upper limit of the compression ratio during PD operation is about 15 to 20. Exceeding this compression ratio causes a significant decrease in efficiency, a rise in discharge gas temperature and an increase in the size of the bearing. Abrasion occurs and the problem of reduced durability occurs.

(Eighth Embodiment) FIG. 11 is a refrigeration cycle diagram of a refrigerator showing an embodiment of the present invention, and FIG. 12 is a timing chart showing the operation and suction pressure change in the embodiment.

The feature of the cycle configuration of the refrigerator in the present embodiment is that no accumulator for storing the liquid refrigerant is installed in the refrigerator compartment 2 and the freezer compartment 3. The feature of the operation in the present embodiment is that the cooling of the freezing compartment 3 is prioritized over the cooling of the refrigerator compartment 2 and the freezing is always performed while the air temperature in the freezing compartment 3 is higher than that in the freezing compartment 2. In addition to cooling only the chamber 3, the PD operation is performed only when switching from the cooling of the freezing chamber 3 to the cooling of the refrigerator compartment 2 as shown in FIG. In addition, as shown in FIG. 12, the second blowing fan 17 is operated during the PD operation, and the PD operation is completed within a time period in which the suction pressure hardly decreases.

As a result, when the cooling of the refrigerator compartment 2 is switched to the cooling of the freezer compartment 3, the liquid refrigerant retained in the first evaporator 8 and the first accumulator 9 installed in the refrigerator compartment 2 is evaporated. During the cooling of the freezing room 3 having a low temperature, the refrigerant evaporates and is collected by the compressor 4 and is returned to the cooling cycle to secure the amount of the circulating refrigerant. Accordingly, the problem of the input loss of the compressor 4 and the decrease in durability due to the decrease in suction pressure can be reduced.

Further, by operating the second blower fan 17, the liquid refrigerant staying in the second evaporator 11 is heated to prevent a temperature drop and a suction pressure drop. By performing the PD operation only for the time that the liquid refrigerant in the chamber 11 runs out, the time can be shortened.
It is possible to reduce the problem of the input loss of the compressor 4 due to the operation and the decrease in durability due to the decrease of the suction pressure.

Here, the point H in FIG.
This is the point in time when the liquid refrigerant in the chamber is exhausted and the refrigerator shifts to the refrigerator compartment cooling mode. Further, the PD operation time can be reduced to about 1/10 as compared with the case where an accumulator for storing a large amount of liquid refrigerant is installed in the freezing room 3.

When there is no large difference in the internal volume between the freezing room cooling cycle and the freezing room cooling cycle and no accumulator is installed in the freezing room 3, it is preferable that no accumulator is installed in the freezing room 2. Since no excess refrigerant is generated only in the refrigerator compartment cooling cycle, the refrigerator compartment 2
It is not necessary to install an accumulator inside,
When shifting from the refrigerator compartment cooling mode to the freezer compartment cooling mode, the time for collecting the liquid refrigerant stored in the first evaporator 8 can be reduced.

(Embodiment 9) FIG. 13 is a diagram showing a driving operation and a change in suction pressure according to an embodiment of the present invention.

[0095] The cycle configuration of the refrigerator in the present embodiment is the same as that of the eighth embodiment.

Further, as shown in FIG. 13, the movement operation in the present embodiment is characterized in that the mode is shifted from the cooling mode to the freezing mode and from the freezing mode to the cooling mode. In both cases, the PD operation is not performed.

As a result, the accumulator for storing a large amount of liquid refrigerant is not installed in the freezing room 3 and the refrigeration room 2,
The PD operation is abolished by reducing the shortage of the amount of circulating refrigerant generated at the time of transition to the cooling mode, and the problem of the input loss of the compressor 4 due to the PD operation and the decrease in durability due to the decrease in the suction pressure can be solved.

(Embodiment 10) FIG. 14 is a refrigeration cycle diagram of a refrigerator according to an embodiment of the present invention, and FIG. 15 is a timing chart showing a kinetic operation and a change in suction pressure when the power is turned on in the embodiment. is there.

The cycle configuration of the refrigerator in the present embodiment is characterized in that no accumulator for storing the liquid refrigerant in the refrigerator compartment 2 and the freezer compartment 3 is provided, and the freezer compartment is provided in parallel with the second expansion mechanism 10. The point is that the starting expansion mechanism 22 is installed so as to form a cooling cycle. Further, the feature of the kinetic operation in the present embodiment is that, as shown in FIG. 15, in the freezing room cooling mode at the initial stage after the power is turned on, the refrigeration side flow path connected from the condenser 5 to the second expansion mechanism 10 is closed. The third flow path switching valve 21 is operated so as to open a startup flow path from the condenser 5 to the startup expansion mechanism 22.

As a result, an accumulator for storing a large amount of liquid refrigerant is not provided in the freezing room 3 and the refrigeration room 2,
The PD operation is abolished by reducing the shortage of the amount of the circulating refrigerant generated at the time of the transition to the cooling mode, and the problem of the input loss of the compressor 4 due to the PD operation and the decrease in durability due to the decrease in the suction pressure can be solved. Further, by cooling the freezing compartment 3 using the starting expansion mechanism 22 having relatively low resistance in the initial stage after the power is turned on, the evaporation temperature is raised to increase the refrigeration temperature as shown by the solid line of the suction pressure change in FIG. Capability can be increased and pull-down time can be reduced. Also, in the case of an overload in which the air temperature in the freezing room 3 rises, if the starting expansion mechanism 22 is used in the same manner as in the initial stage after the power is turned on, the evaporating temperature is increased to increase the freezing capacity, and the freezing room is increased. It can also be expected that the temperature of the air in 3 is rapidly reduced.

In this embodiment, the flow path from the condenser 5 is switched by using the three-flow path switching valve 21.
If the first expansion mechanism 7, the second expansion mechanism 10, and the starting expansion mechanism 22 are provided with a closing mechanism, the three flow path switching valve 21
It is possible to switch the flow path without using. Further, the flow path resistance of the first expansion mechanism 7, the second expansion mechanism 10, and the starting expansion mechanism 22 may be a constant resistance such as a capillary or a variable resistance such as an expansion valve. Further, the resistance variable range of the second expansion mechanism 10 may be expanded, and the resistance may be reduced at the time of power-on or overload to substitute the startup expansion mechanism 22.

(Embodiment 11) FIG. 16 is a refrigeration cycle diagram of an evaporator of a refrigerator and the periphery thereof according to an embodiment of the present invention. The cycle configuration, operation, and suction pressure change of the refrigerator in the present embodiment are the same as those in the ninth embodiment.

The features of the configuration of the evaporator in the present embodiment are that the capacity of the first evaporator 8 and the second evaporator 11 is designed to be excessive, and as shown in FIG. The second evaporator 1 includes a straight pipe portion 11a, a corner portion 11b, a cooling fin 11c for exchanging heat with air in the freezing compartment 3, and a rising pipe 11d serving as an outlet pipe.
1 is used.

As a result, the accumulator for storing a large amount of liquid refrigerant is not installed in the freezing room 3 and the refrigeration room 2,
The PD operation is abolished by reducing the shortage of the amount of the circulating refrigerant generated at the time of the transition to the cooling mode, and the problem of the input loss of the compressor 4 due to the PD operation and the decrease in durability due to the decrease in the suction pressure can be solved. Further, as shown in FIG. 16, the refrigerant flow path of the second evaporator 11 is set to a flow facing the air flow in the freezing chamber 3, and the second expansion mechanism 10 on the inlet side is provided.
By separating the riser pipe 11d, which is the outlet side pipe,
By keeping the dryness of the refrigerant at the outlet of the second evaporator 11 close to 100%, it is easy to secure the superheat in the suction pipe of the compressor 4, and it is possible to prevent the dew of the suction pipe and the suction of the liquid refrigerant. A decrease in the durability of the compressor 4 can be prevented.

Here, the second evaporator 11 shown in FIG.
In the configuration described above, the air in the freezing chamber 3 is supplied from below by the second blower fan 17 and heat is exchanged mainly in the lower part of the second evaporator 11, so that the second expansion mechanism 10 on the inlet side is provided. Is the lowest. Therefore, the riser pipe 11d, which is the outlet side pipe, is installed on the side opposite to the second expansion mechanism 10, thereby preventing cooling near the second expansion mechanism 10 and drying the refrigerant at the outlet. The degree is kept close to 100%. In addition, since the outlet pipe is the rising pipe 11d, it is possible to prevent the liquid refrigerant from entering the suction pipe of the compressor 4 due to a change in the refrigerant flow rate.

In the present embodiment, the second evaporator 1
Although only the configuration 1 is described, the same effect can be expected with the same configuration for the first evaporator 8. In addition, in order to secure superheat in the suction pipe section of the compressor 4,
It is desirable to perform heat exchange between the suction pipe section and the high temperature section of the cooling cycle.

(Embodiment 12) FIG. 17 is a refrigeration cycle diagram of a refrigerator showing an embodiment of the present invention. The driving operation and suction pressure change in the present embodiment are described in Embodiment 9
Is the same as

A feature of the cycle configuration of the refrigerator in the present embodiment is that a comp accumulator 24 is provided in the suction pipe of the compressor 4.

As a result, the accumulator for storing a large amount of liquid refrigerant is not installed in the freezing room 3 and the refrigeration room 2,
The PD operation is abolished by reducing the shortage of the amount of the circulating refrigerant generated at the time of the transition to the cooling mode, and the problem of the input loss of the compressor 4 due to the PD operation and the decrease in durability due to the decrease in the suction pressure can be solved. Further, as shown in FIG. 17, by providing the comp accumulator 24 in the suction pipe portion of the compressor 4, when the liquid refrigerant enters the suction pipe of the compressor 4 due to a change in the refrigerant flow rate, the comp accumulator 24 is placed in the comp accumulator 24. The compressor 4 can be temporarily stored, and the durability of the compressor 4 can be prevented from deteriorating due to dew on the prevention suction pipe and suction of the liquid refrigerant.

[0110]

As described above, according to the present invention, a refrigerator having a plurality of evaporators having different evaporation temperatures and using a cooling cycle in which the evaporators are switched to perform cooling is used under all conditions. And give priority to cooling the freezer,
The cooling cycle is switched after the evaporating temperature during freezing compartment cooling becomes lower than the evaporating temperature during freezing compartment cooling, and the PD operation is performed only immediately before switching from the freezing compartment cooling cycle to the refrigerating compartment cooling cycle. By using the control method, the PD operation at the time of switching from the refrigerator compartment cooling cycle to the freezer compartment cooling cycle can be omitted, and the problems of power loss and reduced durability due to the PD operation can be reduced.

Further, by using a control method of switching the cooling cycle without PD operation without installing an accumulator in the freezer compartment and the refrigerator compartment, the amount of refrigerant to be refrigerated can be reduced and the PD at the time of switching the cooling cycle can be reduced. By omitting the operation, it is possible to solve the problems of power loss and reduced durability associated with the PD operation.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle diagram of a refrigerator according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing the operation of the refrigerator and changes in suction pressure of the refrigerator according to the first embodiment of the present invention.

FIG. 3 is a timing chart showing the operation of the refrigerator and changes in suction pressure of the refrigerator according to the second embodiment of the present invention.

FIG. 4 is a refrigeration cycle diagram of the refrigerator according to the third embodiment of the present invention.

FIG. 5 is a timing chart showing the operation of the refrigerator and a change in suction pressure according to the third embodiment of the present invention;

FIG. 6 is a timing chart showing the operation of the refrigerator and changes in suction pressure of the refrigerator according to the fourth embodiment of the present invention.

FIG. 7 is a timing chart showing the operation of the refrigerator and a change in suction pressure of the refrigerator according to the fifth embodiment of the present invention.

FIG. 8 is a timing chart showing the operation of the refrigerator and changes in suction pressure of the refrigerator according to the sixth embodiment of the present invention.

FIG. 9 is a refrigeration cycle diagram of a refrigerator according to a seventh embodiment of the present invention.

FIG. 10 is a timing chart showing the operation of the refrigerator and changes in suction pressure of the refrigerator according to the seventh embodiment of the present invention.

FIG. 11 is a refrigeration cycle diagram of the refrigerator according to the eighth embodiment of the present invention.

FIG. 12 is a timing chart showing the operation of the refrigerator and changes in suction pressure of the refrigerator according to the eighth embodiment of the present invention.

FIG. 13 is a timing chart showing the operation of the refrigerator and changes in suction pressure of the refrigerator according to the ninth embodiment of the present invention.

FIG. 14 is a refrigeration cycle diagram of the refrigerator according to the tenth embodiment of the present invention.

FIG. 15 is a timing chart showing the operation of the refrigerator and changes in suction pressure of the refrigerator according to the tenth embodiment of the present invention.

FIG. 16 is a refrigeration cycle diagram of a main part of a refrigerator according to an eleventh embodiment of the present invention.

FIG. 17 is a refrigeration cycle diagram of a refrigerator according to a twelfth embodiment of the present invention.

FIG. 18 is a refrigeration cycle diagram of a conventional refrigerator.

FIG. 19 is a timing chart showing the operation of a conventional refrigerator and changes in suction pressure.

[Explanation of symbols]

 Reference Signs List 4 compressor 5 condenser 6 flow switching valve 7 first expansion mechanism 8 first evaporator 9 first accumulator 10 second expansion mechanism 11 second evaporator 12 second accumulator 13 check valve 14 Refrigerator box 15 Machine room

Claims (12)

[Claims] 1. A refrigerator having a refrigerator compartment and a freezer compartment, comprising a compressor, a condenser, a flow path switching valve, a first expansion mechanism, and a first evaporator installed in the refrigerator compartment. Vessel, a first accumulator installed in the refrigerator compartment, a second expansion mechanism, a second evaporator installed in the freezer compartment, and a second accumulator installed in the freezer compartment And a closed loop formed by the compressor, the condenser, the flow path switching valve, the first expansion mechanism, the first evaporator, and the first accumulator, and the first expansion mechanism. Connecting the second expansion mechanism, the second evaporator, the second accumulator, and a check valve so as to be in parallel with the first evaporator and the first accumulator; By switching the flow of the refrigerant, the refrigerator compartment and the front The cooling of the freezing compartments is performed independently of each other, and the cooling of the freezing compartments is prioritized, and immediately before switching from the cooling of the freezing compartments to the cooling of the refrigerator compartment, the channel switching valve or the second A control means for operating the compressor in a state where the flow of the refrigerant into the second evaporator is shut off using the expansion mechanism of (1). 2. A cooling fan for facilitating heat exchange between the air in the freezer compartment and the second evaporator, wherein the refrigerant is supplied to the second evaporator immediately before switching from cooling of the freezer compartment to cooling of the refrigerator compartment. The refrigerator according to claim 1, further comprising control means for operating the compressor while operating the blower fan in a state where the inflow of air is shut off. And a heater disposed on the surface of the second accumulator, wherein the flow of refrigerant into the second evaporator is shut off immediately before switching from cooling of the freezing compartment to cooling of the refrigerator compartment. The refrigerator according to claim 1 or 2, further comprising control means for operating the compressor while energizing the heater. 4. A low-capacity operation of a compressor having a variable capacity compressor in a state in which the flow of refrigerant into a second evaporator is shut off immediately before switching from cooling of a freezing compartment to cooling of a refrigerator compartment. The refrigerator according to any one of claims 1 to 3, further comprising control means for performing the operation. 5. A method of using a flow path switching valve or a first expansion mechanism in a state in which the flow of refrigerant into a second evaporator is shut off immediately before switching from cooling of a freezing compartment to cooling of a refrigerator compartment. The refrigerator according to any one of claims 1 to 4, further comprising control means for operating the compressor while allowing a small amount of refrigerant to flow into the evaporator. 6. A cooling fan for cooling a compressor or a condenser, wherein the cooling of the refrigerant into the second evaporator is interrupted immediately before switching from cooling of the freezing compartment to cooling of the refrigerator compartment. The control means for operating the compressor while operating the fan is provided.
A refrigerator according to any one of the preceding claims. 7. A refrigerant detecting device for detecting the temperature or pressure of refrigerant staying in the second accumulator, wherein the flow of refrigerant into the second evaporator is reduced immediately before switching from cooling of the freezing compartment to cooling of the refrigerator compartment. 7. The control device according to claim 1, further comprising control means for operating the compressor until the temperature or pressure of the refrigerant obtained by the detection means falls below a predetermined value in the shut-off state. Refrigerator according to item. 8. A refrigerator having a refrigerator compartment and a freezer compartment, comprising: a compressor, a condenser, a flow path switching valve, a first expansion mechanism, and a first evaporator installed in the refrigerator compartment. A second expansion mechanism, a second evaporator installed in the freezing chamber, the compressor, the condenser, the flow path switching valve, the first expansion mechanism, and the first evaporation. Forming a closed loop with the vessel, connecting the second expansion mechanism, the second evaporator and the check valve so as to be in parallel with the first expansion mechanism and the first evaporator, The refrigerating compartment and the freezing compartment are cooled independently by switching the flow of the refrigerant by the flow path switching valve, and no accumulator is provided in the freezing compartment and the refrigerating compartment, and the freezing compartment is not provided. Immediately before switching from the cooling of the refrigerator to the cooling of the refrigerator compartment, the flow of the refrigerant to the second evaporator. A refrigerator comprising a control means for operating the compressor for a predetermined time in a state in which the compressor is turned off. 9. A refrigerator having a refrigerator compartment and a freezer compartment, comprising: a compressor, a condenser, a flow path switching valve, a first expansion mechanism, and a first evaporator installed in the refrigerator compartment. A second expansion mechanism, a second evaporator installed in the freezing chamber, the compressor, the condenser, the flow path switching valve, the first expansion mechanism, and the first evaporation. Forming a closed loop with the vessel, connecting the second expansion mechanism, the second evaporator and the check valve so as to be in parallel with the first expansion mechanism and the first evaporator, The refrigerating compartment and the freezing compartment are cooled independently of each other by switching the flow of the refrigerant by the flow passage switching valve, and no accumulator is installed in the freezing compartment and the refrigerating compartment, and the first The compressor is operated in a state where the flow of the refrigerant into the evaporator and the second evaporator is shut off Refrigerator characterized by using no control means. 10. The refrigerator according to claim 8, further comprising control means for reducing the flow path resistance of the second expansion mechanism when the power is turned on, as compared with the time of steady operation. 11. The apparatus according to claim 8, wherein the first evaporator and the second evaporator have excessive capacity, and superheat is maintained during a steady operation. A refrigerator according to claim 1. 12. The refrigerator according to any one of claims 8 to 11, wherein an accumulator is provided near the compressor.