JPH08136112A - Refrigerator - Google Patents

Abstract

PURPOSE: To increase the amount of residence of a refrigerant owing to inflow of the refrigerant into an evaporator at the initial stage of defrosting and hence improve defrosting efficiency by making use of heat transfer with the refrigerant by closing a high pressure valve and a low pressure valve retarding from the initiation of the defrosting. CONSTITUTION: There are included a body 1 of a refrigerator having a freezing cycle where there are connected in order annularly a compressor 9, a condenser 10, a capillary tube 11, an evaporator 12, and a suction pipe 13, a defrosting heater disposed in the vicinity of the evaporator 12, high pressure valves 24 and low pressure valves 25 each disposed at connection parts among the evaporator 12, the capillary tube 11, and the suction pipe 13, and valve control means 26 for opening/closing the high pressure valves 24 and the low pressure valves 25 retarding the operation of the defrosting heater 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator refrigeration cycle.

[0002]

2. Description of the Related Art FIG. 8 shows the structure of a refrigerator disclosed in Japanese Patent Laid-Open No. 4-203756 as a conventional example. In the figure, reference numeral 1 denotes a main body of a refrigerator, which is partitioned by a partition wall 2 into a refrigerating room 3 and a freezing room 4. A refrigerating compartment door 5 and a freezing compartment door 6 are installed in the refrigerating compartment 3 and the freezing compartment 4, respectively. A machine room 7 is provided at a lower rear portion of the main body 1.

On the back side of the freezing room 4, a cooling room 8 is installed which is separated from the freezing room 4. A compressor 9 is installed in the machine room 7, a condenser 10, a capillary tube 11, a cooling room 8
The evaporator 12 and the suction pipe 13 installed in the above are sequentially connected in an annular shape to form a cooling system. The capillary tube 11 and the suction pipe 13 are installed in close contact with each other in heat exchange.

In the vicinity of the evaporator 12, a defrosting heater 14 as a heater is installed, and defrosting detection means 15 for detecting the start and end of defrosting are installed. In addition, a blow-out air passage 17 and a suction air passage for communicating the air inside the refrigerator 16 and the refrigerating compartment 3 and the freezing compartment 4 and the cooling compartment 8 for circulating the air cooled by the evaporator 12 to the refrigerating compartment 3 and the freezing compartment 4. Have eighteen.

Further, inside the freezing compartment 4, a freezing compartment temperature adjusting means 19 for controlling the temperature of the freezing compartment 4 by stopping the operation of the compressor 9 is installed. A refrigerating compartment temperature adjusting mechanism 21 for controlling the temperature inside the refrigerating compartment 3 is installed in the opening 20 of the refrigerating compartment 3 of the blowing air passage 17. Further, 22 is an accumulator provided between the suction pipe 13 and the compressor 9, and 23 is an evaporator accumulator provided at the outlet of the evaporator 12 in the cooling chamber 8.

Regarding the refrigerator constructed as described above,
The operation will be described below. When the compressor 9 is operated, the internal fan 16 starts operating, and cooling of the refrigerating chamber 3 and the freezing chamber 4 starts. The high-temperature and high-pressure refrigerant discharged from the compressor 9 exchanges heat with the outside air in the condenser 10 to be condensed and liquefied, and then flows into the capillary tube 11. The refrigerant is decompressed by the capillary tube 11 and evaporated by the evaporator 12, and the internal fan 16 exchanges heat with the air in the refrigerating chamber 3 and the freezing chamber 4.

The refrigerant evaporated and vaporized here passes through the suction pipe 13 as it is and returns to the compressor 9. At this time, since the capillary tube 11 and the suction pipe 13 are disposed in a heat exchange manner, the vaporized low temperature refrigerant in the suction pipe 13 and the capillary tube 11
The liquefied liquid refrigerant having a high temperature therein exchanges heat, and the enthalpy of the liquid refrigerant decreases and increases in the supercooling direction and the gas refrigerant increases in the heating direction. This increases the refrigeration effect and improves the refrigeration capacity of the cooling system.

When the temperature of the refrigerating compartment 3 reaches a predetermined temperature, the refrigerating compartment temperature adjusting mechanism 21 causes the refrigerating compartment 3 of the blow-out air passage 17 to be cooled.
The inner opening 20 is closed to prevent the air cooled in the cooling chamber 8 from flowing into the refrigerating chamber 3.

When the temperature of the freezer compartment 4 reaches a predetermined temperature, the freezer compartment temperature adjusting means 19 stops the compressor 9 and stops cooling. When the temperature of the freezer compartment 4 rises and reaches a certain temperature, the freezer compartment temperature adjusting means 19 operates the compressor 9 again and starts cooling.

By continuing the operation, the evaporator 12 is
When the frost formation progresses to reach a predetermined frost formation amount, the defrost detection means 15 detects the frost formation and starts the defrost operation. When the defrosting operation is started, the compressor 9 and the internal fan 16 are stopped, and at the same time, the defrosting heater 14 is energized. At this time, the evaporator 12 is heated by the heat generated by the defrosting heater 14,
Thaw the frost.

After that, when the defrost detecting means 15 detects the completion of melting of the frost, the defrosting heater 14 is de-energized, the compressor 9 and the internal fan 16 are started to operate again, and the refrigerating room 3 and the freezing room are restarted. Start cooling of No. 4.

[0012]

However, in the above configuration, particularly in the case of defrosting at a low ambient temperature, the temperature of the evaporator 12 heated by the defrosting heater 14 after the compressor 9 is stopped. On the contrary, the temperature of the condenser 10 and the suction pipe 13, which are low due to the influence of the outside air temperature, is high.

Then, the refrigerant in the evaporator 12 serves as a heat carrier medium for maintaining the thermal equilibrium between the evaporator 12 on the high temperature side and the low temperature side, and one of them passes through the capillary tube 11 toward the condenser 10 on the low temperature side. Backflow, and the other,
It tries to flow out toward the accumulator 22 through the suction pipe 13. As a result, almost no refrigerant exists in the evaporator 12. As described above, the outflow of the refrigerant from the evaporator 12 during defrosting causes the defrosting efficiency to deteriorate in the defrosting method, which largely depends on the heat transfer of the heated refrigerant rather than the radiant heat by the defrosting heater 14, and causes defrosting. This causes a decrease in cooling efficiency due to an increase in time and an increase in temperature inside the refrigerator.

In the subsequent startup of the compressor 9, since the refrigerant is not present in the evaporator 12 having a relatively internal volume upstream of the suction pipe 13, the compressor 9 is then placed in a vacuum state. I am forced to drive.

Furthermore, since the discharge pressure on the high-pressure side of the compressor 9 does not rise and the pressure difference between the discharge pressure and the suction pressure remains low due to the operation in this vacuum state, the condenser becomes a liquid state and becomes a liquid state. It becomes difficult to recirculate the refrigerant staying in 10 into the system through the capillary tube 11 having a large pressure loss, and the influence of low outside temperature is added.
The circulating amount of the refrigerant will continue to be in short supply.

From the above, not only is the cooling capacity insufficient due to the deterioration of defrosting efficiency and the shortage of the refrigerant circulation amount, but also the cooling effect of the circulating refrigerant on the sliding parts of the compressor 9 and the circulation of the refrigerant after being dissolved in the refrigerant. The refrigerating machine oil does not provide a lubricating effect, which causes a great stress to the compressor 9 and reduces the durability of the compressor 9 and has a risk of damage.

The present invention solves the above problems, and an object of the present invention is to provide a refrigerator that enhances defrosting efficiency and prevents a decrease in the refrigerant flow rate at the time of startup after defrosting.

[0018]

To achieve the above object, a refrigerator according to the present invention is a refrigeration system in which a compressor, a condenser, a capillary tube, an evaporator and a suction pipe are sequentially connected in an annular shape. For the operation of the defrosting heater installed near the evaporator body, the defrosting heater installed near the evaporator, the high pressure valve and low pressure valve installed at the connection between the evaporator and the capillary tube, and the suction pipe, and the defrosting heater. The valve control means opens and closes the high pressure valve and the low pressure valve with a delay.

Further, the compressor discharge pressure detecting means and the evaporator pressure detecting means are provided.

Further, a compressor temperature detecting means for detecting the compressor temperature and an evaporator temperature detecting means for detecting the temperature of the evaporator are provided.

[0021]

[Function] With the above-described structure, not only is the refrigerant prevented from flowing out of the evaporator during defrosting,
A time is provided from the compressor stop to the closing of the high-pressure valve and the low-pressure valve, and the refrigerant flowing into the evaporator at the initial stage of defrosting is retained in the evaporator by operating with a delay for a predetermined time, and that refrigerant is used as a heat medium. The defrosting efficiency is enhanced by promoting the convection effect in the evaporator by using it, and at the time of starting the compressor, especially when starting the compressor after defrosting at low ambient temperature, It is possible to prevent the vacuum operation of the compressor by preventing a temporary decrease in the flow rate of the refrigerant after startup, which is caused by the shortage of the refrigerant retention amount.

Further, since the compressor discharge pressure detecting means and the evaporator pressure detecting means are provided, it is possible to detect the pressure change at which the refrigerant flows into the evaporator and then flows out at the initial stage of defrosting. Defrosting using the convection effect can be performed in a state where the flow path is cut off and the refrigerant retention amount is the largest, and the defrosting efficiency can be improved.

Further, since the compressor temperature detecting means for detecting the compressor temperature and the evaporator temperature detecting means for detecting the temperature of the evaporator are provided, after the refrigerant flows into the evaporator at the initial stage of defrosting, By capturing the timing at which the temperature shifts to the condensation part due to the reversal of the temperature accompanying the progress of defrosting by the temperature change, it is possible to defrost in the state where the refrigerant retention amount is the largest, and it is possible to improve the defrosting efficiency. .

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. For the same configuration as the conventional example,
The detailed description thereof is omitted and the same reference numerals are given.

FIG. 1 shows a refrigerating cycle diagram of the refrigerator in the first embodiment. 24 and 25 are the evaporator 1 respectively
2, capillary tube 11 and suction pipe 1
A high-pressure valve and a low-pressure valve that are respectively installed and operated at the connecting portions with 3, and 26 is a valve control unit that controls the opening and closing of the high-pressure valve 24 and the low-pressure valve 25 by cumulatively delaying the operation of the defrosting heater.

The operation will be described below. Evaporator 12
When the frost is advancing and reaches a predetermined amount of frost, the defrost detecting means 15 detects the frost and starts the defrosting operation. When the defrosting operation is started, the compressor 9 and the internal fan 16 are stopped, and at the same time, the defrosting heater 14 is energized. Simultaneously with this, the valve control means 26 outputs a signal aiming at the timing when the integration is started, the evaporator 12 is sufficiently heated and the refrigerant starts to flow out, and the high pressure valve 24 and the low pressure valve 25 are closed.

After that, the refrigerant is trapped in the closed circuit, and the frost is melted by the radiant heat of the defrosting heater 14 and the heat conduction of the evaporator 12 in addition to the convection action of the heated refrigerant.
After that, when the defrost detecting means 15 detects the completion of melting of frost, the energization of the defrost heater 14 is terminated. Defrosting heater 1
Similarly to the end of energization to 4, the valve control means 26 starts integration and outputs a signal after integration for a predetermined time. Received this,
The high-pressure valve 24 and the low-pressure valve 25 are opened again, and at the same time, the compressor 9 and the in-compartment fan 16 start operating to start cooling the refrigerating chamber 3 and the freezing chamber 4 again.

As described above, according to this embodiment, during defrosting, the refrigerant flows into the evaporator due to the condensation and movement of the refrigerant due to the high / low pressure difference and the temperature difference after the operation is stopped, and the retention amount is further increased as compared with the operating state. By closing the valve at the time of increase, in defrosting using refrigerant convection of the entire evaporator, heat loss due to outflow of the defrosting heater is prevented, and sufficient refrigerant is secured as a heat medium to improve efficiency. Good defrosting is possible. Further, when the compressor is subsequently started, sufficient refrigerant is ensured in the evaporator, so that it is possible to prevent the insufficient flow rate of the refrigerant after the start and prevent the vacuum operation.

Next, a second embodiment will be described. FIG. 2 shows a refrigeration cycle diagram of a refrigerator in the second embodiment, and FIGS. 3 and 4 show block diagrams of electric circuits. Two
Reference numeral 7 is a compressor discharge pressure detecting means, and 28 is an evaporator pressure detecting means.

Next, the operation will be described. With the stop of the compressor 9, the high pressure and the low pressure move toward the balance direction. The compressor pressure detecting means 27 for detecting the pressure on the high pressure side and the evaporator pressure detecting means 28 for detecting the pressure on the low pressure side eventually reach the balance of a predetermined pressure difference or conversely when the defrosting heater 14 is energized. When the pressure detector 28 detects that the pressure has exceeded the limit, a signal is output and the high pressure valve 24 and the low pressure valve 25 are closed. After that, the high-pressure valve 24 and the low-pressure valve 25 are opened in accordance with the start timing of the compressor 9 to shift to the normal operation state.

As described above, according to this embodiment, the compressor discharge pressure detecting means and the evaporator pressure detecting means are provided, so that the refrigerant is accompanied by the reversal of the pressure difference due to the heating of the evaporator during defrosting. Since it is possible to detect the state in which the refrigerant retention amount is large before the start of outflow, it is possible to secure an effective heat medium at the time of defrosting and improve the defrosting efficiency.

Next, a third embodiment will be described. FIG. 5 shows a refrigeration cycle diagram of the refrigerator in the third embodiment, and FIGS. 6 and 7 show block diagrams of electric circuits. Two
Reference numeral 9 is a compressor temperature detecting means, and 30 is an evaporator temperature detecting means.

Next, the operation will be described. When the compressor 9 is stopped, the refrigerant in the system moves toward the balance in temperature and pressure. The evaporator 12 that was at a low temperature during operation is slightly heated by the movement of the high temperature refrigerant from the condenser 10 due to the pressure balance after the stop, but thereafter, the condensation and transfer to the evaporator 12 that is at a still lower temperature continues. However, if the temperature rise by the defrosting heater 14 progresses and the temperatures detected by the evaporator temperature detecting means 30 and the evaporator temperature detecting means 29 become equal, the movement of the refrigerant is stopped. Here, the evaporator temperature detecting means 30
And the evaporator temperature detecting means 29 detects that the detected temperature difference reaches or becomes equal to a predetermined value and outputs a signal to close the high pressure valve 24 and the low pressure valve 25. After that, the high-pressure valve 24 and the low-pressure valve 25 are opened in accordance with the start timing of the compressor 9 to shift to the normal operation state.

As described above, according to this embodiment, since the compressor temperature detecting means and the evaporator temperature detecting means are provided, the refrigerant starts to flow out as the temperature rises due to heating of the evaporator during defrosting. Since it is possible to detect the previous state in which the amount of accumulated refrigerant is the largest, it is possible to secure an effective heat medium for defrosting and improve defrosting efficiency.

[0035]

As described above, according to the present invention, a compressor, a condenser, a capillary tube, an evaporator, and a main body of a refrigerator having a refrigeration cycle in which a suction pipe is sequentially connected in an annular shape, and an evaporator are provided. The defrosting heater installed near the device, the high-pressure valve and low-pressure valve installed at the connection between the evaporator and the capillary tube, and the suction pipe, and the high-pressure valve and low-pressure valve that are delayed after the defrosting heater is activated. Not only does it prevent the refrigerant from flowing out of the evaporator during defrosting by being configured with valve control means that opens and closes, but it also provides a time from the compressor stop to the closing of the high-pressure valve and the low-pressure valve, with a delay of a predetermined time. The defrosting efficiency is increased by making the refrigerant that flows into the evaporator in the initial stage of defrost stay in the evaporator by operating it as a heat medium to promote the convection effect in the evaporator. In addition, when the compressor is started, especially when starting the compressor after defrosting at low ambient temperature, it is possible to prevent a temporary decrease in the refrigerant flow rate after startup, which is caused by the shortage of the refrigerant retention amount in the evaporator. Thus, the vacuum operation of the compressor can be prevented.

Further, since the compressor discharge pressure detecting means and the evaporator pressure detecting means are provided, it is possible to detect the pressure change in which the refrigerant flows into the evaporator and then flows out at the initial stage of defrosting. Defrosting using the convection effect can be performed in a state where the flow path is cut off and the refrigerant retention amount is the largest, and the defrosting efficiency can be improved.

Further, since the compressor temperature detecting means for detecting the compressor temperature and the evaporator temperature detecting means for detecting the temperature of the evaporator are provided, after the refrigerant flows into the evaporator at the initial stage of defrosting, By capturing the timing at which the temperature shifts to the condensation part due to the reversal of the temperature accompanying the progress of defrosting by the temperature change, it is possible to defrost in the state where the refrigerant retention amount is the largest, and it is possible to improve the defrosting efficiency. .

[Brief description of drawings]

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

FIG. 2 is a refrigeration cycle diagram of a refrigerator according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a compressor operation circuit of FIG.

FIG. 4 is a block diagram showing the valve control circuit of FIG.

FIG. 5 is a refrigeration cycle diagram of a refrigerator according to a third embodiment of the present invention.

6 is a block diagram showing a compressor operating circuit of FIG.

7 is a block diagram showing the valve control circuit of FIG.

FIG. 8 is a refrigeration cycle diagram of a conventional refrigerator.

[Explanation of reference numerals] 1 main body 9 compressor 10 condenser 11 capillary tube 12 evaporator 13 suction pipe 14 defrost heater 24 high pressure valve 25 low pressure valve 27 compressor discharge pressure detection means 28 evaporator pressure detection means 29 compressor temperature Detecting means 30 Evaporator temperature detecting means

Claims (3)

[Claims] 1. A main body of a refrigerator having a refrigeration cycle in which a compressor, a condenser, a capillary tube, an evaporator, and a suction pipe are sequentially connected in an annular shape, and defrosting installed near the evaporator. A heater, a high-pressure valve and a low-pressure valve respectively installed at the connection between the evaporator, the capillary tube and the suction pipe, and valve control means for opening and closing the high-pressure valve and the low-pressure valve after delaying the operation of the defrosting heater are provided. Fridge. 2. The opening and closing of the high pressure valve and the low pressure valve are controlled by the outputs of the compressor discharge pressure detection means, the evaporator pressure detection means, and the compressor discharge pressure detection means and the evaporator pressure detection means. The refrigerator according to claim 1. 3. A compressor temperature detecting means for detecting a compressor temperature, and an evaporator temperature detecting means for detecting an evaporator temperature,
The refrigerator according to claim 1, wherein opening and closing of the high pressure valve and the low pressure valve are controlled by the outputs of the compressor temperature detecting means and the evaporator temperature detecting means.