JPS6350629B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cooling device such as a refrigerator having a plurality of cold storage chambers with different temperatures, and its purpose is to improve the coefficient of performance of a compressor and improve the operating efficiency of the cooling device. At the point.

Conventionally, a typical cooling system for cooling multiple cold compartments with different temperatures using a single refrigeration unit is the cooling system for home refrigerators and refrigerators, which basically employs the cooling system shown in Figure 1. Was.

In Fig. 1, 1 is a compressor, and this compressor 1
The refrigerant liquid discharged from the condenser 2 and liquefied in the condenser 2 is
The pressure is reduced in the first capillary tube 3, and a portion of the liquid is evaporated in a refrigerating evaporator 5 disposed within the refrigerating compartment 4, at which time the refrigerating compartment 4 is cooled. The gas-liquid two-phase refrigerant that has exited the refrigeration evaporator 5 is depressurized again in the second capillary 6, and the remainder is evaporated in the refrigeration evaporator 8 disposed in the freezing compartment 7. 7. Cool. The refrigerant gas exiting the refrigeration evaporator 8 is sucked into the compressor 1 via the accumulator 9. The temperature inside each refrigerator is controlled by starting and stopping the compressor 1 using a temperature controller (not shown) disposed in either the refrigerator compartment 4 or the freezer compartment 7.

In the refrigerator-freezer configured as described above, the suction pressure of the compressor 1 is very low pressure in the refrigeration evaporator 8.
Therefore, no matter how high the evaporation pressure of the refrigeration evaporator 5 is, the coefficient of performance of the compressor 1 is extremely poor, and the cooling system is forced to operate inefficiently. . Moreover, as mentioned above, since the temperature inside the refrigerator must be adjusted depending on the temperature inside one of the refrigerators, there is a drawback that the temperature inside the other refrigerator remains unchanged.

On the other hand, in order to enable independent control of the temperature inside each refrigerator, one evaporator 8 is installed in the freezer compartment 7, and the refrigerator compartment 4 controls the indoor temperature by damper control. A cooling system in which the temperature of the chamber 7 is controlled by turning on and off the compressor 1 has become common in recent years. Although this method allows independent control of the temperature in both chambers, the evaporation temperature of the evaporator 8 still depends on the temperature of the freezer compartment 7, so the suction pressure of the compressor 1 is low and the efficiency of the cooling system is extremely low. Bad things don't change. Furthermore, when this method is used, the refrigerator compartment 4 is communicated with the freezer compartment 7 via a damper, which causes the problem of excessive dryness inside the refrigerator compartment 4, and furthermore, the amount of frost on the evaporator 8 increases. However, there were disadvantages such as the need for frequent defrosting.

The present invention has been made in order to improve the various drawbacks of the above-mentioned conventional devices, and includes evaporators for cooling each cooling chamber provided in a plurality of cooling chambers having different cold storage temperatures, and these evaporators are connected in parallel. At the same time, the time for flowing refrigerant to each evaporator is set separately so that the refrigerant does not flow at the same time, thereby improving the coefficient of performance of the compressor. At the same time, the refrigerant liquid that cannot be evaporated in the low-temperature side evaporator is completely evaporated in the high-temperature side evaporator. The refrigerant gas from the low-temperature side evaporator is superheated by the high-temperature side evaporator, the heat of the refrigerant passing through the low-temperature evaporator is recovered, and the low-temperature side evaporator is defrosted using the high-temperature gas discharged from the compressor. By using refrigerant gas and performing a cooling operation using the high-temperature side evaporator, the operating efficiency of the entire cooling system is improved.

The details of the present invention will be explained below using a household refrigerator-freezer as an example.

FIG. 2 is a cooling system diagram showing an embodiment of the present invention, in which 1 is a compressor, 2 is a condenser, 4 is a refrigerating compartment, 5 is a refrigerating evaporator disposed in the refrigerating compartment 4, 7 is a freezing chamber, 8 is a freezing evaporator disposed within the freezing chamber 7, and 9 is an accumulator. 3
6 is a first capillary tube as a first pressure reducer disposed upstream of the refrigerant passage of the refrigeration evaporator 5, and 6 is a second pressure reducer disposed upstream of the refrigerant passage of the refrigeration evaporator 8. 10 is a first on-off valve disposed upstream of the refrigerant passage of the first capillary 3; 11 is a three-way valve disposed downstream of the freezing evaporator 8; One side of the valve 11 communicates with the refrigerant suction passage of the compressor 1 (shown as a→b in FIG. 2), and the other side communicates with the refrigerant suction passage of the compressor 1 (shown as a → b in FIG. 2), and the other side communicates with the refrigerant suction passage of the compressor 1 through the check valve 12 and the first bypass passage 23 upstream of the first capillary tube 3. It communicates with the side. Reference numeral 13 designates a second on-off valve provided in a refrigerant passage that is provided to communicate from the outlet of the check valve 12 to the inlet of the refrigerating evaporator 5. The three-way valve 11 and the third on-off valve 13 constitute refrigerant control.

Further, the series refrigerant circuit of the first on-off valve 10, the first capillary tube 3, and the refrigeration evaporator 5 is connected in parallel with the series refrigerant circuit of the second capillary tube 6, the refrigeration evaporator 8, and the three-way valve 11. 2 and the above-mentioned accumulator 9. 14 is a second bypass path connected to the discharge side of the compressor 1 and the inflow side of the refrigeration evaporator 8 via a third on-off valve 15.

The embodiment shown in FIG. 2 is similar to a conventional parallel evaporator cooling system, but is fundamentally different.

First, in order to match the evaporation pressures of evaporators at different temperature levels to the same suction pressure, the conventional apparatus required a pressure adjustment section after the high temperature side evaporator, but this is not necessary in the present invention. In other words, the characteristic operation of the present invention is that refrigerant is not allowed to flow into both evaporators 5 and 8 at the same time. The refrigerant liquid exiting the condenser 2 is transferred to the high-temperature side, that is, the refrigeration refrigerant circuit, which is composed of a refrigeration refrigerant circuit, a first on-off valve 10, a first capillary tube 3, and a refrigeration evaporator 5, so that the refrigerant liquid exits the condenser 2 is kept at both indoor temperatures. The coefficient of performance of the compressor 1 is improved by maintaining the evaporation pressure of the refrigeration evaporator 5 high when cooling the refrigerator compartment 4 by distributing it in chronological order according to changing conditions, and Freezing is achieved by completely evaporating the refrigerant liquid that cannot be completely evaporated in the refrigerating device 8 in the refrigerating evaporator 5, or by superheating the refrigerant gas coming out of the refrigerating evaporator 8 in the refrigerating evaporator 5. The refrigerant evaporator 8 recovers heat from the refrigerant that has passed through the refrigerant evaporator 8, and the refrigerant liquid during defrosting of the refrigerating evaporator 8 is evaporated by the refrigerating evaporator 5 to perform a cooling operation. Together, these improve the operating efficiency of the entire cooling system.

FIG. 3 is an operation control block diagram of the domestic refrigerator-freezer shown in FIG. 2, excluding the defrosting operation system, in which 16 is a temperature detection sensor disposed in the refrigerator compartment 4, and 17 is a temperature detection sensor disposed in the freezing compartment 7. The temperature detection sensor 18 is a temperature controller for the refrigerator compartment, and when the detected value from the temperature detection sensor 16 rises and exceeds a predetermined value for the refrigerator compartment 4, it outputs an ON signal, and when the detected value decreases, it outputs an ON signal. When the detected value falls below the predetermined lower limit value, the first OFF signal is activated, and when the detected value decreases and reaches a temperature value slightly higher than the predetermined lower limit value, that is, the second predetermined limit value, the second OFF signal is activated. Outputs the OFF signal. Note that the output signal line a of this temperature controller 18 is an ON signal, and the first
An OFF signal and a second OFF signal are output, and the output signal line b outputs a first OFF signal. Reference numeral 19 is a temperature controller for the freezer compartment, which outputs an ON signal when the detected value from the temperature detection sensor 17 rises and exceeds a predetermined upper limit value for the freezer compartment 7, and outputs an ON signal when the value detected by the temperature sensor 17 rises and falls below a predetermined lower limit value. When this happens, an OFF signal is output. 20 is turned on by the ON signal of this temperature controller 19 and the first OFF signal of the temperature detector 18.
AND circuits such as AND gates that output signals,
21 is an OR gate that outputs an ON signal based on either the ON signal of this AND gate 20 or the ON signal of the temperature controller 18; 1 is this OR gate 21;
The compressor is driven by the ON signal of the temperature controller 18, 10 is a first opening/closing valve that opens with the ON signal of the temperature controller 18 and closes with the second OFF signal, and 11 is the AND gate 20.
The ON signal changes the flow path from a to b, and the OFF signal changes the flow path from a to b.
→ It is a three-way valve that switches to c. 13 is opened by the second OFF signal from the temperature controller 18, and the first
This is a second on-off valve that closes with an OFF signal and is normally closed.

In the configuration as described above, when the temperature of the refrigerator compartment 4 is higher than the predetermined upper limit temperature, the temperature controller 18 outputs a signal from the temperature detection sensor 16.
Since the ON signal is output, the first on-off valve 10 is opened, the three-way valve is moved from a to c, the second on-off valve 13 is closed, and the compressor 1 is driven via the OR gate 21. Then, the refrigerant flows through the second capillary tube 6 with high resistance.
It does not flow into the refrigerator, but instead passes through the first capillary tube 3 and only through the refrigerating evaporator 5 to cool the inside of the refrigerating compartment 4. When the refrigerator compartment 4 is cooled and becomes lower than the predetermined upper limit temperature to a second predetermined lower limit value that is slightly higher than the lower limit temperature, and the freezing compartment 7 is higher than the predetermined upper limit temperature, the second predetermined temperature from the temperature controller 18 is The OFF signal closes the first on-off valve 10 and opens the second on-off valve 13. Note that the flow path of the three-way valve 11 remains from a to c. Then, the refrigerant leaving the condenser 2 passes through the second capillary tube 6 and the freezing evaporator 8 to cool the inside of the freezer 7. Furthermore, it passes through a→c of the three-way valve 11, the check valve 12, and the second on-off valve 13, and enters the refrigeration evaporator 5, where the heat of the low-temperature refrigerant is recovered, and at the same time, the refrigerant evaporated at low temperature is superheated. The refrigerator compartment 4 is cooled down to some extent. At this time, if the inside of the refrigerator compartment 4 has been cooled down to below the predetermined lower limit temperature and the temperature inside the freezer compartment 7 has not yet fallen to the predetermined lower limit temperature of the freezer compartment, the first OFF signal from the temperature controller 18 is activated. The AND gate 20 outputs an ON signal in response to the ON signal from the temperature controller 19, and this output switches the flow path of the three-way valve 11 from a to b to prevent refrigerant from flowing into the refrigeration evaporator 5. , the refrigerator compartment 4 will no longer be cooled.
Also, at this time, the second on-off valve 13 is closed.

When both cooling chambers 4, 7 are below the predetermined lower limit temperature, a signal is output from the temperature controllers 18, 19 based on the detected values from the temperature detection sensors 16, 17, and the AND gate 20,
The operation of the compressor 1 is stopped via the OR gate 21.

Next, when frost builds up on the refrigeration evaporator 8 and it is necessary to defrost it, the first on-off valve 10 and the third on-off valve 15 are opened, and the air is discharged from the compressor 1. The high temperature refrigerant gas is passed through the second condenser without flowing through the condenser 2.
The high-temperature refrigerant gas is introduced into the freezing evaporator 8 to melt the frost in the freezing evaporator 8, and the high-temperature refrigerant gas is liquefied. This refrigerant liquid passes through the three-way valve 11 from a to c, and since the third on-off valve 13 is closed, it is guided to the upstream side of the first capillary tube 3, where it is depressurized and evaporated in the refrigerating evaporator 5. Refrigerator room 4
It cools the inside and recovers heat during defrosting. Normally, the evaporation temperature of the refrigerant in the refrigeration evaporator 5 is high, so frost rarely builds up on the evaporator 5, but if you open the third on-off valve 13 at this time, the refrigeration evaporator 5
It can also defrost.

FIG. 4 is a cooling system diagram showing another embodiment of the present invention, and 22 is a three-way valve 1 in FIG.
This is a fourth on-off valve installed downstream of the refrigerant branch path to the check valve 12 instead of the check valve 1. This fourth on-off valve 22 has a flow path of the three-way valve 11 in FIG.
Open when the change is from a to c, closed when the first on-off valve 10 is open, and closed when the first on-off valve 10 is closed. It opens and closes depending on the temperature situation. Even with this configuration, it has the same function and the same effect.

In the above embodiment, a capillary tube is used as a pressure reducer, but it goes without saying that an expansion valve or the like may also be used, and even in the case of multiple systems with two or more load sides, the pressure reduction device is adapted to each temperature level. The present invention can be applied to multiple systems by setting a refrigerant control valve for each system and setting refrigerant control valves for multiple systems.

As described above, the present invention can improve the operating efficiency of the compressor and the cooling system as a whole by distributing refrigerant to evaporators with different evaporation pressures in time series. Since independent control is possible and the cooling of the high-temperature side cold storage chamber is performed at an appropriately high evaporation temperature, problems such as drying of the high-temperature side cold storage chamber do not occur.

Furthermore, in a conventional refrigeration system in which evaporators are connected in parallel, refrigerant flows through both evaporators at the same time. Although this was required later, this is not necessary in the present invention, and the refrigerant sucked into the compressor is sufficiently superheated during low-temperature side cooling operation, which also improves efficiency. Furthermore, when defrosting the low-temperature side evaporator, the refrigerant liquid condensed in this evaporator is evaporated in the high-temperature side evaporator via the first pressure reducer and used for cooling the high-temperature cooling chamber, making it even more efficient. Improvements can be made.

[Brief explanation of drawings]

Fig. 1 is a diagram of the cooling system of a conventional domestic refrigerator-freezer, Fig. 2 is a diagram of the cooling system of a refrigerator-freezer for domestic use showing an embodiment of the present invention, and Fig. 3 is a control diagram excluding the defrosting operation control system. The block diagram, FIG. 4, is a cooling system diagram showing another embodiment of the present invention. The same symbols in the figures indicate the same or corresponding parts, 1
is a compressor, 2 is a condenser, 3 is a first capillary, 4 is a refrigerator compartment, 5 is a refrigeration evaporator, 6 is a second capillary, 7 is a freezing compartment, 8 is a freezing evaporator, 10 is a first On-off valve, 11 is a three-way valve, 12 is a check valve, 13 is a second on-off valve, 14 is a second bypass path, 15 is a third on-off valve, 16 and 17 are temperature detection sensors, 18,
19 is a temperature controller, 20 is an AND gate, 21 is a
OR gate 23 is the first bypass path.

Claims (1)

[Scope of Claims] 1. A refrigerant circuit consisting of a plurality of cooling chambers with different cold storage temperatures, a first on-off valve, a pressure reducer, and an evaporator provided in each cooling chamber and connected in series in the refrigerant flow direction. , one compressor and a condenser connected in series in a parallel circuit in which each of these refrigerant circuits are connected in parallel, detects the temperature of each of the above cooling chambers, and directly supplies the refrigerant from the above condenser to each of the above refrigerants. a temperature controller that controls the first on-off valve so that the refrigerant flows selectively into one of the circuits; a first bypass path that bypasses refrigerant to the pressure reducer inlet; a refrigerant path connected from the check valve outlet of the first bypass path to the evaporator inlet of the refrigerant circuit connected to the first bypass path; , a second on-off valve for opening and closing the refrigerant path, provided on the evaporator outlet side,
A refrigerant control valve that allows the refrigerant discharged from the evaporator to flow into either the first bypass path or the suction side of the compressor; A cooling device comprising a bypass path and a third on-off valve provided in the second bypass path to open and close the bypass path. 2. The cooling device according to claim 1, wherein when the cooling chamber consists of two chambers, the first on-off valve of the low-temperature side refrigerant circuit is omitted by constructing the pressure reducer with a capillary tube. 3. The cooling device according to claim 1 or 2, wherein the refrigerant control valve is a three-way valve provided at a branch section that branches from the evaporator outlet to the first bypass path. 4. The refrigerant control valve is configured with a fourth on-off valve provided in the flow path from the evaporator outlet to the compressor suction side and closer to the compressor than the branch part that branches to the first bypass path. A cooling device according to claim 1 or 2.