JPS58221354A - Refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a refrigeration device such as a refrigerator, which is composed of a compressor, a condenser, a pressure reducing device, and an evaporator, and which performs defrosting operation with a heater.

A cooling system used in a conventional refrigerator includes a compressor 1, as shown in FIG. Condenser 2. A pressure reducing device 4° evaporator 6 is arranged in a ring shape with pipes.

When the compressor 1 is operated intermittently to adjust the temperature, the pressure reducing device 4 acts as a mere pressure equalizing pipe when the compressor is stopped, and the high-temperature, high-pressure refrigerant in the condenser 2 is transferred to the low-temperature, low-pressure refrigerant through the pressure reducing device 4. The refrigerant flows into the evaporator 5, creating a large heat load on the inside of the refrigerator, and has drawbacks in terms of cooling efficiency, such as a decrease in refrigerant on the high-pressure side, which slows down the refrigerant supply to the evaporator when the next compressor is started. was.

In order to improve this problem, as shown in Fig. 1, a solenoid valve 3 is installed between the outlet of the condenser 2 and the pressure reducing device 4, and when the compressor is in operation, it is energized to open the valve flow path and stop the compressor. When the electromagnetic valve 3 is de-energized and the valve flow path is closed, the evaporator 6
This makes it possible to prevent high-temperature, high-pressure refrigerant from flowing into the tank. On the other hand, regarding the defrosting operation in this type of improved refrigeration system, the switching contact 7b of the timer 7 is set to NC as shown in Fig. 2.
The timer 7 is switched when the operating time of the compressor 1, which is located on the side and is in a cooling operation, reaches a predetermined time, and when the thermostat 6, which controls the temperature inside the refrigerator by causing the compressor 1 to operate intermittently by opening and closing, is closed, the timer 7 is switched. Contact 7b is N.

During the defrosting operation using the heater 8, the electromagnetic valve 3 is energized to open the valve flow path as shown by the broken line in FIG. There are cases where the solenoid valve 3 is de-energized and the valve flow path is closed.

First, if we assume that conventional example A is an example in which the solenoid valve is open during defrosting operation, the operation graph of the cooling system during defrosting operation is as shown in Figure 4, and the pressure characteristics at that time are as shown in Figure 6. As shown by the broken line, the solenoid valve 3 is opened during defrosting operation, so the pressure reducing device acts as a pressure equalizing pipe, and the evaporator temperature remains in the condenser from the start of defrosting until the evaporator temperature reaches approximately 0°C. High-temperature, high-pressure refrigerant flows into the evaporator and becomes an auxiliary heat source for heating the evaporator, promoting defrosting, but after that, as the evaporator is heated by the defrost heater and the evaporator temperature rises, the pressure on the low-pressure side decreases. The refrigerant on the low-pressure side gradually rises and is heated, and then flows back to the high-pressure side via the pressure reducing device 4 and balances the pressure of the entire high and low pressure. This has the advantage that the high-low pressure differential P1'-P2' becomes extremely small, making it easier to restart the compressor, but on the other hand, it has the disadvantage that the defrosting efficiency is poor and the defrosting time becomes longer.

On the other hand, conventional example B is an example in which the solenoid valve 3 is closed during defrosting operation.
Then, the operation graph of the cooling system during defrosting operation is as shown in Figure 4, and the pressure characteristics at that time are as shown by the dashed line in Figure 6. Although the inflow of high-temperature, high-pressure refrigerant at the initial stage of defrosting does not assist in defrosting, it is ultimately possible to raise the temperature to a specified level with a small amount of refrigerant in the evaporator during defrosting. However, since the high pressure remains high during defrosting, the high and low pressure difference P1''-P2 at the end of defrosting as detected by the bimetal thermostat 9 becomes large. In order to start the compressor, the electric motor of the compressor requires excessive torque, and depending on the conditions, it may be difficult to start the compressor.

The present invention focuses on this kind of problem, and provides a refrigerant control valve between the condenser outlet and the pressure reducing device inlet, and during cooling operation, the opening and closing of the refrigerant control valve is synchronized with the operation and stop of the compressor. During defrosting operation, the refrigerant control valve is opened only from the start of defrosting until the evaporator temperature rises to around 0° C., thereby simultaneously solving the drawbacks of conventional examples A and H described above.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a compressor, 2 is a condenser, 3 is a solenoid valve, 4 is a capillary tube, and 6 is an evaporator, each of which is connected to form an annular cooling cycle. Further, in FIG. 3, 6 is a thermostat, which controls the temperature inside the refrigerator by causing the compressor 1 to operate intermittently. After that, the operating time of the compressor 1 is accumulated and the defrost heater 8 is periodically energized to cool the evaporator 6.
This is a timer for defrosting the drive motor 7a.
and a switching contact 7b. 9 is a bimetal thermostat for detecting the end of defrosting, and 1o is another bimetal thermostat installed in a part of the evaporator 5, whose contacts are set to open at approximately 0°C or higher, and one end is to the power supply via the thermostat 6;
The other end is connected in series with the electromagnetic valve 3 and connected to a power source, and is configured to be short-circuited during cooling operation.

The operation of this configuration will be explained next. When the switching contact 7b of the timer 7 is on the N, C side (N, C/) side and the temperature control thermostat 6 is closed, the switching contact 7b is on the N, C side (N, C/) side, regardless of whether the bimetal thermostat 10 is open or closed.
The solenoid valve 3 is energized by the short circuit 11 of the bimetal thermostat 10 via the N and C contacts of b, the solenoid valve 3 is opened, the compressor 1 is operated, and the inside of the refrigerator is cooled. When the temperature reaches a certain level, the temperature regulating thermostat 6 is opened, the current is cut off, the solenoid valve 3 is closed, and the compressor 1 is stopped. As a result, when the compressor 1 is stopped, the high pressure side refrigerant is transferred to the solenoid valve 3.
Since the inflow into the evaporator 5 through the capillary tube 4 is interrupted, the heat load is prevented from inflowing into the evaporator 6 while the compressor 1 is stopped. Further, when the operating time of the compressor 1 is accumulated for a certain period of time by the drive motor 7a of the timer 7, the switching contact is
@O') At the same time when the K is switched and the compressor 1 is stopped, the defrosting heater 8 is turned on via the metal thermostat 9.
At this time, the timer drive motor 7a is short-circuited by the bimetal thermostat 9 and stops, but the switching contact 7b of the solenoid valve 3 changes from N to N.
・Electrification continues through the bimetal thermostat 10, which has been released from the short-circuit state by switching to 0',
Keep the valve flow path open. As a result, the high-temperature high-pressure refrigerant remaining in the condenser 2 flows into the evaporator 6 and becomes an auxiliary heat source for heating the evaporator 6, promoting defrosting. After that, as defrosting progresses and the temperature of the evaporator 6 rises to around 0°C, the metal thermostat 10 operates to open the contacts, cut off the power to the solenoid valve 3, and close the valve flow path. .

At this time, the high and low pressures are temporarily released at a low pressure.

As defrosting progresses further in this state, the refrigerant in the evaporator 6, which is heated by the defrost heater 8 and its pressure increases, does not flow back into the condenser 2, improving the defrosting efficiency and shortening the defrosting time. That's all. When the temperature of the evaporator 6 finally rises to a predetermined temperature, the bimetal thermostat 9 is opened and the defrosting heater 8 stops generating heat, and at the same time, the timer drive motor 7a is energized and starts operating.

After that, after a certain waiting time has elapsed, the switching contact 7b changes to N-0 (N-0') due to the action of the cam plate of the timer 7, etc.
→N-C (N-C') and at the same time as the solenoid valve 3 is opened, the compressor 1 is started and the cooling operation is resumed. As shown by the solid line in Figure 5, the pressure change in the cooling system during defrosting shows exactly the same pressure change as in conventional example A from the start of defrosting until the evaporator temperature rises to 0°C. Once the pressure is low, the high and low pressures are almost balanced. (Point 23 in Figure 6) After that, when the bimetal thermostat 1o is opened and the solenoid valve 3 is closed, the pressure on the low pressure side increases due to the heating of the defrosting heater 8, but the backflow to the high pressure side is blocked. , the high-pressure side pressure remains low, and as a result, when the compressor 1 is restarted after defrosting (the example of the present invention shown in Fig. 4), the high-low pressure is reversed, and the high-pressure side pressure P Since the relationship is such that the low side pressure P2 is low, the required torque in the compression stroke is small, and the compressor 1 can be started easily. Figure 4 shows the timer 7, defrost heater 8, and solenoid valve 3 that correspond to pressure changes in the cooling system on each side.
, each operation and stop of the compressor 1 are shown.

As is clear from the above embodiments, the present invention provides a refrigerant control valve such as a solenoid valve between a condenser and a pressure reducer such as a capillary tube, and opens and closes the refrigerant control valve in synchronization with the operation and stop of the compressor. let me,
During defrosting, the refrigerant control valve is opened only from the start of defrosting until the evaporator temperature rises to around 0°C. Therefore, conventional refrigeration equipment equipped with a solenoid valve had advantages and disadvantages depending on whether the solenoid valve was opened or closed during defrosting, but with the control of the refrigerant control valve during defrosting of the present invention, defrosting From the start until the evaporator temperature reaches around 0℃, the high-temperature, high-pressure refrigerant is effectively used as an auxiliary heat source for the defrost heater to accelerate defrost, and after that, defrost is performed by closing the refrigerant control valve. Since the defrosting efficiency is increased without letting the refrigerant heated by the frost heater escape to the high pressure side, the overall defrosting time can be shortened compared to the conventional example. On the other hand, when the compressor is restarted after defrosting, the high and low pressures, which are once roughly balanced at low pressure with the evaporator temperature around 0°C, are then heated on the low pressure side and cut off from the high pressure side. Under this condition, the pressure reverses and the pressure on the high pressure side becomes lower, making it easy to restart.

As described above, the present invention can eliminate the drawbacks of both conventional examples and at the same time take advantage of the advantages of each, and has extremely high practical effects.

[Brief explanation of the drawing]

FIG. 1 is a cooling system piping diagram showing a conventional example and an embodiment of the present invention, FIGS. 2 and 3 are electrical circuit diagrams of the conventional example and the present invention corresponding to FIG. 1, and FIG. 4 and FIG. '6
The figure is a graph showing the operation graph of the cooling system during defrosting of the conventional example and the present invention, and the corresponding pressure change.

Claims (1)

[Claims] A compressor, a condenser, a pressure reducer, and an evaporator are connected in sequence, and a thermostat that senses the internal temperature controls the operation and stopping of the compressor, and a heater defrosts the evaporator. At the same time, a refrigerant control valve is provided between the condenser outlet and the evaporator inlet, and this refrigerant control valve is opened and closed in synchronization with the operation and stop of the compressor. Refrigeration device 0 configured to open the refrigerant control valve only until the temperature of the refrigerator rises to around 0°C.