JP2003207250A - Refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a refrigerant quantity, and to enhance efficiency in a cooling cycle using a combustible refrigerant. <P>SOLUTION: A closed loop is formed of a compressor 12, a condenser 2, a passage control means 13, a first pressure reducing means 7, and a first evaporator 3. A second pressure reducing means 8 and a second evaporator 5 are connected so as to become parallel to the first pressure reducing means 7 and the first evaporator 3. Since cooling is performed by alternately switching the two evaporators 3 and 5 by the cooling cycle for arranging the passage control means 13 on the inlet side of the first pressure reducing means V and the second pressure reducing means 8, pipe capacity of a cooling system and the refrigerant quantity can be reduced more than a cooling system for performing cooling by one evaporator and a cooling system for performing cooling by flowing the refrigerant in parallel to a plurality of evaporators. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator that uses a flammable refrigerant and a variable capacity compressor to reduce the amount of refrigerant and improve efficiency.

[0002]

2. Description of the Related Art FIG. 9 shows a schematic view of an example of a conventional cooling cycle and a refrigerator.

Reference numeral 1 is a constant speed compressor, 2 is a condenser, 3 is a first evaporator disposed in a refrigerating compartment 4, and 5 is a freezing compartment 6.
It is a second evaporator disposed inside.

Reference numeral 7 denotes a first capillary disposed upstream of the refrigerant circuit of the first evaporator 3 for cooling the refrigerating chamber,
Reference numeral 8 is a second capillary arranged upstream of the refrigerant circuit of the second evaporator 5 for cooling the freezing compartment, and 9 is provided downstream of the second evaporator 5 for cooling the freezing compartment. It is a check valve.

Reference numeral 10 is a first on-off valve provided on the downstream side of the refrigerant circuit of the first evaporator 3, and 11 is a second on-off valve provided on the upstream side of the refrigerant circuit of the second capillary 8. Is.

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

The operation of the refrigeration cycle is performed as follows. First, the refrigerant compressed by the compressor 1 is condensed and liquefied by the condenser 2. The condensed refrigerant is decompressed by the first capillary 7 or the second capillary 8, flows into the first evaporator 3 and the second evaporator 5, respectively, and is evaporated and vaporized, and then again flows into the compressor 1. Inhaled.

The first evaporator 3, the second evaporator 5 and the refrigerating chamber 4, which have a relatively low temperature due to the evaporative evaporation of the refrigerant,
Each room is cooled by heat exchange of the air in the freezing room 6.

The cooling operation of the freezer-refrigerator is performed as follows by the temperature detecting means and control means of each room (not shown).

When each of the temperature detecting means in the refrigerating room 4 and the freezing room 6 detects a temperature increase of a predetermined value or more, the compressor 1 is started and the refrigerating cycle is operated. The first opening / closing valve 10 is opened and the second opening / closing valve 11 is closed until the temperature detecting means of the refrigerating chamber 4 becomes equal to or lower than a predetermined value.

As a result, the refrigerant does not flow into the second evaporator 5 but flows only into the first evaporator 3. The setting of the evaporation temperature at this time is 0 to −5 ° C. for the temperature setting of the refrigerating chamber 4 of about 5 ° C., which is 2 to 2.5 times the normal evaporation temperature of −25 to −30 ° C. The compressor can be operated with the coefficient of performance of.

When the refrigerating chamber 4 is cooled and the temperature drops, and the temperature detecting means detects a temperature below a predetermined value, the first opening / closing valve 10
Is closed and the second on-off valve 11 is opened.

As a result, the refrigerant flows into the second evaporator 5, and the freezer compartment 6 is cooled. At this time, the evaporation temperature of the refrigerating cycle is cooled at a normal evaporation temperature when the temperature setting of the freezing chamber is about -18 ° C.

As described above, the refrigerating chamber 4 and the freezing chamber 6 are alternately cooled repeatedly by distributing the refrigerant supply time to the evaporator. Therefore, when the refrigerating chamber 4 is cooled, the first refrigerant is independently evaporated. By circulating it to the reactor, a low-pressure pressure regulating valve is not required and a high evaporation temperature (0 to -5 ° C) is possible, the compression ratio of the compressor 1 can be reduced, and operation is performed with a high coefficient of performance to improve efficiency. It is a thing.

Further, since the check valve 9 has a high evaporation temperature during cooling of the refrigerating chamber 4, it prevents the refrigerant from flowing into the second evaporator 5.

Further, when the freezing chamber 6 is cooled, the amount of the refrigerant is smaller than that during the cooling of the refrigerating chamber 4, so that the amount of the refrigerant is usually excessive. However, since the first opening / closing valve 10 is provided on the downstream side of the first evaporator 3 and is closed, it is possible to store the refrigerant in the first evaporator 3 and to adjust the amount of the refrigerant (for example, , Patent Document 1.).

[0017]

[Patent Document 1] Japanese Patent Publication No. 62-22396

[0018]

However, in the refrigerator as described above, in view of the characteristics of the rotary type or reciprocating type compressors that are usually used in refrigerators, the compression ratio increases as the evaporation temperature increases. The coefficient of performance is improved by the reduction of
At the same time, there is a problem that the refrigerating capacity of the compressor 1 is greatly increased due to the decrease in the specific volume of the sucked refrigerant due to the higher evaporation temperature.

Now, what kind of problems will occur when the refrigerating capacity is increased will be described below.

In the conventional example, the coefficient of performance of the compressor is increased by about 2 to 2.5 times by raising the evaporation temperature from -25 to -30 ° C, which is a normal evaporation temperature, to 0 to -5 ° C. At the same time, the refrigerating capacity of the compressor becomes 3 to 5 times.

The efficiency cannot be improved unless the refrigerating capacity of the compressor, which is 3 to 5 times as large, is used effectively for cooling the refrigerating chamber 4.

In order to effectively use the refrigerating capacity of the compressor 1 for cooling the refrigerating compartment 4, it is necessary to expand the heat exchange capacity between the first evaporator 3 and the air in the refrigerating compartment 4.

The heat exchange capacity of the evaporator is expressed by the product of the heat transmission coefficient, the heat exchange area and the heat exchange temperature difference (difference between the evaporation temperature and the air temperature).
The difference between the evaporation temperature that is the source of the heat exchange temperature difference and the refrigerating chamber set temperature is greatly reduced from 30 to 35 deg to 5 to 10 deg, and the heat exchange capacity of the first evaporator 3 is reduced.
In addition, to cope with the increase in the refrigerating capacity of the compressor 1 by 3 to 5 times, the heat exchange capacity of about 9 to 30 times is required.

As described above, a very large heat exchanger is required, which increases the ineffective volume which reduces the storage space of the refrigerator.

Further, if a high capacity and large heat exchanger is required, the amount of required refrigerant also increases, and when using a flammable refrigerant, there is a problem that the danger at the time of refrigerant leakage increases.

Further, when the freezer compartment 6 is cooled, the amount of the refrigerant is smaller than that when the refrigerating compartment 4 is cooled for the above-mentioned reason. Therefore, the refrigerant is reserved in the first evaporator 3 to adjust the surplus refrigerant quantity. Also, the amount of the enclosed refrigerant increases.

Further, when the compressor 1 is started, a transitional period with a large operating loss occurs in which an output corresponding to the input of the compressor 1 is not obtained until the refrigerant is stably supplied to the evaporator. Further, when the cooling of the refrigerating room 4 and the freezing room 6 is switched, a similar transitional period with a large operation loss occurs.

When the increased refrigerating capacity of the compressor 1 is adjusted by the distribution ratio of the switching time, the cooling time of the refrigerating chamber 4 is greatly shortened.

At this time, the transition period in which the operation loss is large is not shortened, and as a result, the time ratio of the transition period to the stable cooling time is increased, resulting in a decrease in efficiency.

Further, the number of times of starting the compressor and switching the cooling operation between the refrigerating room 4 and the freezing room 6 per day increases, resulting in a decrease in efficiency.

It may be possible to cope with the problem by widening the temperature control range of the refrigerating compartment 4 to a lower temperature, but it is not preferable that the temperature fluctuates greatly in terms of keeping the food, and further, the temperature in the refrigerating compartment 4 decreases. If too much, it freezes and damages the stored food.

On the other hand, in order to suppress the refrigerating capacity of 3 to 5 times by miniaturizing the compressor, it is necessary to use a very small compressor, and the refrigerating capacity of the compressor is secured when the refrigerator 4 is cooled. However, when the freezer compartment 6 is cooled, there is a problem that the refrigerating capacity of the compressor is insufficient and the temperature cannot be maintained.

Further, since there are many connection points of the refrigerant circuit, there is a problem that the possibility of refrigerant leakage is relatively high.

The present invention solves the above conventional problems, and an object of the present invention is to provide a cooling cycle and a refrigerator in which the safety of a flammable refrigerant is improved by reducing the amount of the flammable refrigerant. .

It is another object of the present invention to provide a cooling cycle and a refrigerator in which safety is improved when flammable refrigerant leaks by reducing the number of connected pipes in a closed space.

It is another object of the present invention to provide a cooling cycle and a refrigerator which save energy by improving the coefficient of performance and improving the transient characteristics.

It is an object of the present invention to provide a cooling cycle and a refrigerator in which the storage space is expanded by reducing the capacity of the cooling cycle which is an ineffective volume.

[0038]

According to a first aspect of the present invention, a compressor, a condenser, a flow path control means, a first pressure reducing means, a first evaporator, and a first evaporator are provided. A second decompression means, a second evaporator, a check valve, a cooling cycle in which a flammable refrigerant is sealed, a refrigerating compartment, a freezing compartment, and air in the refrigerating compartment to the first evaporator. And a second electric fan for circulating the air in the freezing chamber through the second evaporator, wherein the refrigerating chamber has a high temperature. The first evaporator is provided as a cooler on the side, the second evaporator is provided as a cooler on the low temperature side in the freezer, and the compressor, the condenser, the first pressure reducing means, and the first evaporator are provided. Form a closed loop with the second decompression so that it is parallel to the first decompression means and the first evaporator. The second evaporator and the check valve are connected to each other, and the flow path control means is disposed on the inlet side of the first pressure reducing means and the second pressure reducing means, and the first evaporator and the first pressure reducing means are connected to each other. The refrigerant supply to the two evaporators is alternately switched and the first electric fan and the second electric fan are alternately operated to alternately cool the refrigerating chamber and the freezing chamber, and the compressor is The low pressure container type is characterized in that the amount of the flammable refrigerant enclosed in the cooling cycle is reduced.

With the above construction, in the cooling cycle using the flammable refrigerant, the low pressure container type is used as the compressor, so that the gas refrigerant specific volume in the container increases during the operation of the compressor, and the amount of the refrigerant in the container increases. Can be reduced.

Further, since the cooling is performed by alternately switching the first evaporator and the second evaporator, a refrigerant is flown in parallel with a refrigeration system for cooling with one evaporator or a plurality of evaporators. The piping capacity of the cooling system can be reduced and the amount of refrigerant can be reduced as compared with a refrigeration system that performs cooling.

Further, since the evaporation temperature in the case of cooling in the first evaporator and the evaporation temperature in the case of cooling in the second evaporator are different, high-efficiency refrigeration by reducing the compression ratio in each evaporator. Cycle operation is possible.

Further, since the refrigerant backflow prevention means is provided at the outlet of the second evaporator on the low temperature side, there is no difference in temperature between the evaporators and the refrigerant does not flow into the evaporator on the low temperature side. Since the refrigerant does not lie on the low temperature side during the cooling operation in the first evaporator, the amount of the refrigerant can be kept low.

According to a second aspect of the invention, in the invention of the first aspect, isobutane is used as the flammable refrigerant,
Since a refrigerating machine oil in the compressor container is characterized by using a mineral oil compatible with the isobutane, when using a compatible refrigerating machine oil in which the solubility of the refrigerant increases at low temperature and high pressure, when using When the internal pressure of the container becomes low during the operation of the machine, it is possible to reduce the dissolution of the refrigerant in the refrigerating machine oil and reduce the amount of the refrigerant.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. Detailed description of the same configurations as those of the conventional example will be omitted, and the same reference numerals will be given.

(Embodiment 1) FIGS. 1 and 2 are schematic views of a cooling cycle according to an embodiment of the present invention.

A variable capacity compressor 12 which is a low pressure container type, a condenser 2, an electric three-way valve 13 which is a flow path control means, a capillary 7 which is a first pressure reducing means, a first evaporator 3 and a second evaporator 3. A capillary 8 as a pressure reducing means and a second evaporator 5 are provided, and a closed loop is formed by the variable capacity compressor 12, the condenser 2, the first capillary 7 and the first evaporator 3, and The second capillary 8 and the second evaporator 5 are connected so as to be in parallel with the capillary 7 and the first evaporator 3.

The electric three-way valve 13 is provided on the inlet side of the first capillary 7 and the second capillary 8.

Further, a flammable refrigerant such as an HC refrigerant (propane, isobutane) having a low global warming potential is enclosed as the refrigerant.

With the above construction, in a cooling cycle using a flammable refrigerant, a low-pressure container type is used for the compressor 12, so that the gas refrigerant specific volume in the container increases during the operation of the compressor 12 and The amount of refrigerant can be reduced.

Further, when a compatible refrigerating machine oil such as a combination of isobutane and mineral oil is used, the solubility of the refrigerant increases at low temperature and high pressure. Compressor 12
A large amount of refrigerating machine oil is present in the container, and the compressor 12
By reducing the pressure in the container during operation, it is possible to reduce the amount of refrigerant flowing into the refrigerating machine oil and reduce the amount of refrigerant.
It is even better if an incompatible refrigerator oil is used.

Also, for example, in a system in which an evaporator is arranged for cooling only an object to be cooled in different compartments by a duct and an air blower, and the compartments are separated. As a result, there is little energy loss during heat transfer, which is efficient.

The operation of this cooling cycle will be described below.

By operating the variable capacity compressor 12, a high temperature and high pressure refrigerant is discharged and condensed by the condenser 2 to be liquefied.

The liquefied refrigerant is switched by the electric three-way valve 13 so as to flow into either the first capillary 7 or the second capillary 8.

The refrigerant is decompressed by the first capillary 7 or the second capillary 8 and then flows into the first evaporator 3 or the second evaporator 5 to evaporate and vaporize, and thereby the temperature of the object to be cooled. Lower. The vaporized refrigerant is returned to the compressor 12 again.
Inhaled into.

While the first evaporator 3 and the second evaporator 5 are required to be cooled, the electric three-way valve 13 alternately supplies the refrigerant to cool them alternately.

The cooling is stopped by stopping the compressor 12.

If the cooling loads of the objects to be cooled are equal in order to perform cooling alternately, the ratio of the cooling time of one evaporator is 50% at the maximum, so that it is the maximum at a constant speed compressor. When the cooling cycle is designed based on the load, the refrigerating capacity becomes large and the operating time becomes short in the case of the normal load, and the same problem as in the conventional case occurs, but the variable capacity compressor 12 is used to perform compression depending on the load. The cooling capacity is adjusted by the functional power.

The variable compression capacity is performed by controlling the number of revolutions of an inverter or the like and the piston stroke of a linear compressor or the like.

Since two evaporators are alternately switched to perform cooling and the cooling capacity is adjusted by the compression functional force according to the load, a cooling system in which one evaporator is used for cooling and a plurality of evaporators are connected in parallel. The piping capacity of the cooling system can be reduced, and the amount of the refrigerant can be reduced, as compared with a cooling system in which the cooling medium is caused to flow for cooling.

Although the flow path control means 13 is an electric three-way valve, the same effect can be obtained by installing two two-way valves on the inlet side of the first and second capillaries.

Although the flow path control means 13 is located on the inlet side of the pressure reducing means, respectively, as shown in FIG. 2, the first pressure reducing means 7 and the second pressure reducing means 8 are collectively reduced in pressure. Means 1
4, if the flow path control means 13 is provided on the outlet side of the pressure reducing means 14, the circuit is switched after the pressure of the refrigerant is reduced, so that the operating pressure difference of the flow path controlling means 13 is small and a small torque is sufficient, so that the size can be reduced. Therefore, the power consumption can be reduced.

By changing the evaporation temperature when the first evaporator 3 is used for cooling and when the second evaporator 5 is used for cooling, the set temperature of the object to be cooled may be different. Especially, when a cooling speed is required and the evaporation temperature is desired to be lowered, it is possible to optimize each evaporator. When the set temperature is different, the evaporation temperature is raised in proportion to each temperature to perform a highly efficient cooling cycle operation by lowering the compression ratio, and when the cooling speed is required, the evaporation temperature for cooling is lowered. This is possible.

Since the first evaporator 3 is on the high temperature side and the second evaporator 5 is on the low temperature side, and the check valve 9 serving as the refrigerant backflow preventing means is provided at the outlet of the second evaporator 5. , The refrigerant does not flow into the second evaporator 5 due to the temperature difference between the respective evaporators, and the refrigerant may lie in the second evaporator 5 during the cooling operation in the first evaporator 3. Since there is no refrigerant, the amount of refrigerant can be kept low.

Furthermore, the electric three-way valve 13 is connected to the compressor 12
If the refrigerant circuit to the second evaporator 5 is closed during the stop, the high temperature gas refrigerant in the condenser 2 does not flow into the second evaporator 5 while the compressor 12 is stopped, and the heat of There is no load inflow.

Further, since the pressure of the cooling system is low and balanced during the stop, the pressure difference at the time of starting the compressor 12 is small,
It is possible to reduce the cost and size by reducing the torque of the compressor motor.

When operating from the first evaporator 3 at the next startup, the refrigerant hardly exists in the unused second evaporator 5 but exists in the used first evaporator 3. Therefore, the temperature of the first evaporator 3 used immediately is lowered, and the cooling loss is small.

Further, the electric three-way valve 13 is a solenoid operated type for switching two circuits, and when energized, the circuit is switched in the direction of flowing the refrigerant to the first evaporator 3 and when not energized, the second evaporator 3 is switched. The circuit is switched in the direction in which the refrigerant flows to 5, and a simple and low-cost configuration is possible. Further, since the energization is stopped at the time of stop, the power consumption is reduced.

Although the electric three-way valve 13 is of a solenoid drive type which is simple in structure and control and is low in cost, if it is a self-holding motor drive type such as a pulse motor, power consumption is switched to a flow path. Only during operation,
It is particularly effective in terms of energy saving and has low noise because there is no collision noise of the plunger.

If the condenser is forcibly cooled by an electric fan, the condensing capacity can be improved and the capacity of the condenser can be reduced, which is effective in reducing the amount of refrigerant.

Furthermore, the same effect can be obtained even if the evaporator is forced to circulate air by an electric fan to cool the object to be cooled.

(Second Embodiment) FIG. 3 is a schematic view of a flow path control valve according to another embodiment of the present invention.

The flow path control means 13 connects the first position 15 for opening the refrigerant circuit to the first evaporator 3 and the second position 16 for opening the refrigerant circuit to the second evaporator 5 and the refrigerant circuit. And a third position 17 for blocking.

Further, the seal member 19 eccentrically fixed to the rotary shaft 18 rotationally moves in the cylinder 20 and is stopped at each of the first, second and third positions to be connected to each position. The pipe is closed. The rotation is performed by drive means and transmission means (not shown). Positioning at each position is controlled by the number of drive pulses of the pulse motor, for example.

Positioning may be performed by a position detecting means such as a limit switch.

With the above-described flow path control means 13, when switching the evaporators, the flow path control valve 13 is operated at the first position 15 and the second position 16, and when the compressor 12 is stopped, the third position is set. Since the high and low pressure gas cut is performed at the position 17, the refrigerant is not accumulated in any of the evaporators during the stop, and therefore, when the compressor 12 is started next time, the first evaporator 3 and the second evaporator 5 are not charged. Refrigerant can be supplied immediately and there is little starting loss.

Further, since the high temperature gas refrigerant does not flow into any of the evaporators during stoppage, the heat load can be prevented from flowing in.

(Third Embodiment) FIG. 4 is a schematic view of a refrigerator according to another embodiment of the present invention, and FIG. 5 is a time chart according to the same embodiment.

Reference numeral 21 denotes a freezer-refrigerator box, in which a refrigerating chamber 4 which is a relatively high temperature chamber is arranged in the upper part and a relatively low temperature freezing chamber 6 is arranged in the lower part. For example, a heat insulating material such as urethane. Insulated from the surroundings. Items such as foods are taken in and out via a heat insulating door (not shown).

The refrigerator compartment 4 is usually 3 to 5 ° C. for refrigerated storage.
However, the temperature may be set at a slightly lower temperature, for example, 0 to -3 ° C to improve the freshness, and the user is free to switch the above temperature setting depending on the stored items. In some cases it is possible. Further, in order to keep wine, root vegetables and the like, the temperature may be set slightly higher, for example, around 10 ° C.

The freezing compartment 6 is set at a lower temperature than the refrigerating compartment 4, and is normally -18 to -22 ° C. for frozen storage.
Is set in. Further, in order to improve the freshness, it may be set at a lower temperature, for example, -25 to -30 ° C.

The cooling cycle 22 is the variable capacity compressor 12
The condenser 2, the first pressure reducing means capillary 7 and the first evaporator 3 form a closed loop, and the second pressure reducing means capillary 8 and the second evaporator 5 and the backflow prevention means. A check valve 9 is connected to the first capillary 7 and the first evaporator 3 in parallel.

The electric three-way valve 13 which is the flow path control means is provided on the inlet side of the first capillary 7 and the second capillary 8.

The electric three-way valve 13 is a solenoid operated type, and when energized, the circuit is switched to flow the refrigerant to the first evaporator 3, and when not energized, the refrigerant flows to the second evaporator 5. The circuit is switched to.

The first evaporator 3 is disposed inside the refrigerating compartment 4, for example, at the inner surface of the refrigerating compartment 4, and the indoor air in the refrigerating compartment 4 is passed to the first evaporator 3 for circulation in the vicinity thereof. There is provided a first electric fan 23.

The second evaporator 5 is disposed inside the freezing compartment 6, for example, at the inner surface of the freezing compartment 6 and is adjacent to the freezing compartment 6.
A second electric fan 24 is provided to circulate the room air of (1) through the second evaporator 5 and circulate.

The compressor 12, the condenser 2, the electric three-way valve 13, and the check valve 9 are mechanical parts for reducing the number of pipe connection points in the refrigerator / freezer box 21 from the viewpoint of improving safety when using a flammable refrigerant. It is arranged in the chamber 25.

The compressor 12 is of a low pressure container type in order to reduce the amount of flammable refrigerant used, and the refrigerant returning from each evaporator passes through the compressor suction pipe 26 and is discharged into the internal space of the compressor 12. , And is sucked into the compression mechanism portion 27 and discharged through the compressor discharge pipe 28.

Further, the compressor 12 is of a variable capacity type which can change the refrigerating capacity by controlling the refrigerant circulation amount by controlling the rotation speed by an inverter, for example.

Further, the refrigerating room 4 and the freezing room 6 are provided with temperature detecting means (not shown) for detecting a room temperature, for example, a thermistor, and the variable capacity compressor 12, the electric three-way valve 13 and the first electric motor are provided. A control means (not shown) for controlling the fan 23 and the second electric fan 24 is provided.

Regarding the refrigerator constructed as described above,
The operation will be described.

When the temperature of the refrigerating compartment 4 rises, the temperature detecting means of the refrigerating compartment detects that the temperature exceeds a predetermined temperature (t1u). Upon receiving this signal, the control means operates the compressor 12 and the first electric fan 23 to energize the electric three-way valve 13.

The high-temperature and high-pressure refrigerant discharged by the operation of the compressor 12 is condensed and liquefied by the condenser 2, and the electric three-way valve 1
3, the pressure is reduced in the first capillary 7 and flows into the first evaporator 3.

At this time, the control means controls the compressor 12 by the inverter so as to perform the low rotation operation (r1) with a relatively low refrigerating capacity.

The air in the refrigerating chamber 4 positively exchanges heat with the first evaporator 3 by the operation of the first electric fan 23, so that the refrigerant evaporates and vaporizes in the first evaporator 3. The vaporized refrigerant is sucked into the compressor 12 again. The heat-exchanged air becomes cooler air, lowering the temperature in the room.

When the temperature inside the refrigerating chamber 4 is lowered and the temperature detecting means detects that the temperature is lower than the predetermined temperature (t1l), the control means stops the compressor 12 and the first electric fan 23, and the electric three-way system is operated. The valve 13 is de-energized.

For example, the refrigerating chamber 4 set at a relatively high temperature of 3 ° C. is cooled at a high evaporation temperature that can be operated with a higher coefficient of performance. It is possible to raise the evaporation temperature of.

The setting of the evaporation temperature is determined by the variable width of the capacity of the compressor 12, and the larger the variable width, the higher the evaporation temperature can be made.

In the conventional example, the cooling is performed at the evaporation temperature of 0 ° C. to −5 ° C., but since the variable width of the compressor 12 becomes too large, it is difficult to maintain high efficiency over the entire variable width of the compressor. Also, it is disadvantageous in terms of cost and reliability.

Therefore, the variable width of the compressor 12 is set to 2-3.
About twice, the evaporation temperature is set to about −30 ° C. on the low temperature side and about −10 ° C. to −15 ° C. on the high temperature side.

When the temperature of the freezing compartment 6 rises, the temperature detecting means of the freezing compartment detects that the temperature exceeds a predetermined temperature (t2u). Upon receipt of this signal, the control means receives the compressor 1
2 and the second electric fan 24 are operated, and the electric three-way valve 13
Turn off the power.

At this time, the control means carries out the inverter control of the compressor 12 so as to perform the high rotation operation (r2) which provides a relatively high refrigerating capacity.

The refrigerant is decompressed by the second capillary 8 by the electric three-way valve 13 and flows into the second evaporator 5.

The freezing compartment 6 is cooled by the operation of the second electric fan 23, and the temperature detecting means is set to a predetermined temperature (t2l).
When the lowering is detected, the control means causes the compressor 1
2 and the second electric fan 24 are stopped.

The above operation is repeated to adjust the temperature.

Next, the cooling timing of the refrigerating room 4 and the freezing room 6 will be described with reference to the time chart of FIG.

The refrigerating compartment temperature detecting means detects an increase in the refrigerating compartment temperature and starts cooling as described above (T1).

Even when the temperature detecting means of the freezer compartment detects the temperature rise of the freezer compartment 6, the refrigerating compartment 4 is preferentially cooled until it reaches a predetermined temperature (t1l) (T2).

When the temperature detecting means in the refrigerating room is set to a predetermined temperature (t1
l) When it is detected that the temperature is equal to or lower than that, and when the temperature detecting means of the freezing compartment at this time detects that the temperature is equal to or higher than a predetermined temperature (t2u), the control means switches to cooling of the freezing compartment 6.

By the control means, the electric three-way valve 13 is switched, the refrigerant is supplied to the second evaporator 5, and the refrigerant supply to the first evaporator 3 is stopped. At the same time, the first electric fan 23 stops and the second electric fan 24 operates.
The compressor 12 has a low rotation speed (r1) by inverter control.
To a high rotation speed (r2) (T
3).

While the freezer compartment 6 is being cooled, the temperature of the refrigerating compartment 4 rises again, and when the temperature detecting means in the refrigerating compartment detects a predetermined temperature (t1u) or higher, the control means energizes the electric three-way valve 13. The refrigerant is supplied to the evaporator 3 and the refrigerant supply to the second evaporator 5 is stopped. At the same time, the second electric fan 24
Is stopped and the first electric fan 23 operates. Compressor 1
2 changes the refrigerating capacity from the high speed (r2) to the low speed (r1) by the inverter control (T4).

The refrigerating chamber 4 is preferentially cooled until it reaches a predetermined temperature (t1l), and if the temperature detecting means of the refrigerating chamber detects a temperature equal to or lower than the predetermined temperature (t1l), it is cooled again as described above. Switching is performed and the freezer compartment 6 is cooled (T
5).

If the freezing compartment 6 is cooled and the temperature detecting means detects a temperature equal to or lower than a predetermined temperature (t2l), and the temperature detecting means in the refrigerating compartment at this time detects that the temperature is equal to or lower than the predetermined temperature (t1u). For example, the compressor 12 and the second electric fan 23 are stopped by the control means, and the electric three-way valve 13 is deenergized (T6).

When the temperature of each chamber rises again and becomes equal to or higher than a predetermined temperature (t1u, t2u), cooling is similarly performed.

From the above, when a flammable refrigerant is used, the refrigerating chamber 4 and the freezing chamber 6 are alternately cooled, and the refrigerant is alternately supplied to the first evaporator 3 and the second evaporator 5. Since it is supplied, the coefficient of performance of the compressor 12 can be improved by setting a relatively high evaporation temperature when the refrigerating chamber 4 is cooled. Further, the capacity variable control of the inverter or the like makes it possible to reduce the compressor refrigerating capacity at the time of cooling at a relatively high evaporation temperature of the refrigerating room 4, so that the amount of refrigerant required when cooling the refrigerating room 4 does not increase, The amount of refrigerant sealed can be reduced.

The freezer-refrigerator box 21 is divided by temperature zones, and the refrigerant is alternately supplied to the evaporators for cooling each temperature zone for cooling, so that the conventional cooling system with only one evaporator or a plurality of evaporators is used. Compared to a cooling system in which a refrigerant flows in parallel with an evaporator for cooling, it is like a small freezer and a small refrigerator, so the amount of refrigerant can be reduced.

Furthermore, since the difference in refrigerating capacity between the chambers can be suppressed by varying the capacity of the compressor 12, it is possible to suppress the generation of a large refrigerant surplus, and the surplus refrigerant is not stored in the evaporator. Can be reduced.

Further, since the increase in refrigerating capacity due to the higher evaporation temperature can be suppressed, the refrigerating system can be constructed without making the first evaporator 3 extremely large.

Further, since the refrigerating capacity used for cooling the refrigerating compartment 4 can be suppressed, the cooling time of the refrigerating compartment 4 does not become very short, and the start-up loss of the compressor 14 and the cooling switching loss can be reduced in a ratio. Prevent decline.

Although the cooling of the refrigerating compartment 4 is prioritized in the description of the cooling timing of the refrigerating compartment 4 and the freezing compartment 6, the same effect can be obtained by prioritizing the cooling of the freezing compartment 6.

Furthermore, by using the flammable natural refrigerant R600a as the refrigerant of the refrigeration cycle, it is possible to suppress the compressor refrigerating capacity in the same refrigeration cycle as compared with the normally used refrigerant R134a.

In the variable inverter capacity control of the compressor 12, it is possible to shift the variable width to the high rotation side, and without lowering the extremely low capacity range as the variable capacity width, the efficiency decrease due to the decrease in the rotation speed or It is possible to prevent the reliability from being lowered due to the decrease in the amount of oil supply.

(Fourth Embodiment) FIGS. 6 and 7 are schematic sectional views of a refrigerator according to another embodiment of the present invention.

As shown in FIG. 6, a first suction pipe 29 connected between the first evaporator 3 and the compressor 12.
And the capillary 7, which is the first depressurizing means, are arranged in the heat insulating wall so that heat can be exchanged, and the second suction pipe 30 and the second suction pipe 30 connected between the second evaporator 5 and the compressor 12 are provided. The capillary 8 which is the depressurizing means is disposed in the heat insulating wall so that heat can be exchanged.

Since the backflow preventing means 9 is provided on the downstream side of the second suction pipe 30 and is not arranged in the heat insulating material, the safety at the time of refrigerant leakage is improved. Furthermore, maintainability can also be improved.

The heat exchanging portions may be bundled and brought into close contact with each other by a tape or the like so that the heat insulating material does not wrap around, but it is desirable to improve heat transfer by soldering.

Further, it is advantageous to make the heat exchange distance long in order to sufficiently perform the heat exchange, but if it is too long, the pressure loss of the suction pipe 21 will be large and the efficiency will be lowered, so it is made 1000 mm to 2000 mm.

As a result, by the time the refrigerant exiting the first evaporator 3 returns to the compressor 12 through the first suction pipe 29, heat exchange with the first capillary 7 through which the refrigerant passes. By doing so, the temperature of the compressor suction connection pipe is raised, so that dew condensation can be prevented, and water dripping and rust can be prevented.

Similarly, the refrigerant discharged from the second evaporator 5 also exchanges heat between the second capillary 8 and the second suction pipe 30, so that the temperature of the compressor suction connection pipe is increased.

Further, since the capillaries are cooled, it is possible to increase the refrigerating effect of the cooling cycle 22 and improve the cooling performance without supercooling the condenser 2. This leads to a reduction in the amount of refrigerant compared to.

As shown in FIG. 7, the suction pipe 31 in which the first and second suction pipes are combined is located after the outlet side of the first evaporator and the second evaporator are joined, The capillary 7 which is the first depressurizing means and the capillary 8 which is the second depressurizing means are arranged in the heat insulating wall so that heat exchange is possible. Further, the backflow preventing means 9 is the suction pipe 3
1 Provided on the upstream side and arranged in the heat insulating material.

As a result, the piping arrangement in the heat insulating material of the suction pipe 31 and the capillaries is easy and the cost is low.

Further, since the capillaries on the circuit side, which are always closed, are also pre-cooled, the flow rate of the capillaries can be secured at the time of switching the cooling between the refrigerating chamber 4 and the freezing chamber 6, and the switchability is good, and the efficiency can be improved. .

[0134]

As described above, according to the present invention, it is possible to provide a refrigerating cycle and a refrigerator which can enhance the safety when a flammable refrigerant is used by reducing the amount of the flammable refrigerant.

Further, it is possible to provide a cooling cycle and a refrigerator which can enhance the safety at the time of flammable refrigerant leakage by reducing the number of pipe connections to the closed space.

It is also possible to provide a cooling cycle and a refrigerator that can save energy by improving the coefficient of performance and improving the transient characteristics to improve efficiency.

By reducing the capacity of the cooling cycle which is an ineffective volume, it is possible to provide a cooling cycle and a refrigerator that can expand the storage space.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a cooling cycle according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a cooling cycle according to the same embodiment.

FIG. 3 is a schematic view of flow path control means according to another embodiment.

FIG. 4 is a schematic view of a refrigerator according to another embodiment.

FIG. 5 is an operation time chart of a refrigerator according to another embodiment.

FIG. 6 is a schematic sectional view of a refrigerator according to another embodiment.

FIG. 7 is a schematic cross-sectional view of the refrigerator according to the same embodiment.

FIG. 8 is a schematic sectional view of a conventional refrigerator-freezer.

[Explanation of symbols]

2 condenser 3 first evaporator 4 Refrigerator 5 Second evaporator 6 freezer 7 First decompression means 8 Second decompression means 9 Backflow prevention means 12 Low-pressure container type variable capacity compressor 13 Flow path control means 14 Decompression means 15 First position 16 Second position 17 Third position 25 Machine room 29 First suction pipe 30 Second suction pipe 31 Suction pipe

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuki Hamano             2-3-3 Nojihigashi, Kusatsu City, Shiga Prefecture             Within Matsushita Cold Machinery Co., Ltd. (72) Inventor Tetsuya Saito             2-3-3 Nojihigashi, Kusatsu City, Shiga Prefecture             Within Matsushita Cold Machinery Co., Ltd. F term (reference) 3L045 AA01 AA03 BA01 CA02 DA02                       EA01 GA07 HA02 HA07 JA11                       JA15 JA16 LA09 NA03 PA01                       PA04 PA05

Claims (2)

[Claims] 1. A compressor, a condenser, a flow path control means,
A first decompression means, a first evaporator, a second decompression means, a second evaporator, a check valve, a cooling cycle in which a flammable refrigerant is sealed, a refrigerating chamber, and a freezer. Chamber, a first electric fan that circulates air in the refrigerating chamber through the first evaporator, and a second electric fan that circulates air in the freezing chamber through the second evaporator And a fan, wherein the refrigerating compartment is provided with the first evaporator as a high temperature side cooler, and the freezing compartment is provided with the second evaporator as a low temperature side cooler. Forming a closed loop with the machine, the condenser, the first depressurizing means and the first evaporator, and the second depressurizing means and the second evaporator so as to be in parallel with the first depressurizing means and the first evaporator. The second evaporator and the check valve are connected, and the flow path control means is provided on the inlet side of the first pressure reducing means and the second pressure reducing means. The cooling chamber and the freezer are installed by alternately switching the refrigerant supply to the first evaporator and the second evaporator and operating the first electric fan and the second electric fan alternately. A refrigerator characterized in that the amount of the flammable refrigerant enclosed in the cooling cycle is reduced by cooling the chambers alternately and making the compressor a low-pressure container type. 2. The refrigerator according to claim 1, wherein isobutane is used as the flammable refrigerant, and mineral oil compatible with the isobutane is used as refrigerating machine oil in the compressor container.