JPS6362674B2 - - Google Patents

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.

The cooling system used in conventional refrigerators is
As shown in the figure, a compressor 1, a condenser 2, a pressure reducing device 4,
An evaporator 5 is provided. When the compressor is operated intermittently to adjust the temperature, the pressure reducing device 4 acts as a mere pressure equalizing pipe when the compressor is stopped.
The high-temperature, high-pressure refrigerant in the condenser 2 flows into the low-temperature, low-pressure evaporator 5 through the pressure reducing device, creating a large heat load on the inside of the refrigerator, and the amount of refrigerant on the high-pressure side decreases when the next compressor is started. However, this method has drawbacks in terms of cooling efficiency, such as slow refrigerant supply to the evaporator 5.

In order to improve this problem, a solenoid valve 3 is provided between the outlet of the condenser 2 and the pressure reducing device 4, and the solenoid valve 3 is energized to open the valve flow path when the compressor is in operation, and the solenoid valve 3 is closed when the compressor is stopped. This makes it possible to de-energize and close the valve flow path to prevent high-temperature, high-pressure refrigerant from flowing into the evaporator 5. On the other hand, regarding the defrosting operation in this type of improved refrigeration system, as shown in Fig. 2, the switching contact 7b of the timer 7 is on the Nc side and the cumulative operating time of the compressor 1 in the cooling operation reaches a constant value. When the thermostat 6, which operates the compressor 1 intermittently by opening and closing and controls the temperature inside the refrigerator, is closed, the switching contact 7b switches to the No side, and during the defrosting operation by the heater 8, as shown by the broken line in FIG. There is a case where the solenoid valve 3 is de-energized and the valve flow path is closed, and a case where the solenoid valve 3 is de-energized and the valve flow path is closed as shown by the dashed line in FIG.
In some cases, the valve flow path is closed by energizing the valve.

First, if we assume that conventional example A is an example in which the solenoid valve is closed during defrosting operation, the operation graph of the cooling system during defrosting operation is as shown in Figure 3, and the pressure characteristics at that time are as shown in Figure 4. As shown by the broken line, the high-pressure refrigerant is blocked from flowing into the evaporator during defrosting operation, so the temperature is raised to the specified temperature with less refrigerant in the evaporator, which shortens the defrosting time. However, since the high pressure remains high, the difference in high and low pressure during defrosting operation is large, and the difference in high and low pressure when the compressor is restarted after the timer standby time has elapsed.
P ₁ ′−P ₂ ′ also becomes large, and in order to start the compressor, the compressor motor requires excessive torque, and depending on the conditions, it may be difficult to start the compressor.

On the other hand, if conventional example B is an example in which the solenoid valve is kept open during defrosting operation, the operation graph of each part of the cooling system during defrosting operation is as shown in Figure 3, and the pressure characteristics at that time are as follows. As shown by the dashed line in Figure 4, the solenoid valve is opened during defrosting operation, so the pressure reducing device acts as a pressure equalizing pipe, and the differential pressure at the end of defrosting and the differential pressure after the timer standby time P ₁ ″− _P2 '' has the advantage of being extremely small, making it easier to restart the compressor, but until the high and low pressures are balanced, the high-pressure side refrigerant flows into the evaporator, increasing the refrigerant load, which slows down the defrosting time. It has the disadvantage of being long.

The present invention focuses on this type of problem, and provides a refrigerant control valve between the condenser outlet and the pressure reducing device inlet, and synchronizes the refrigerant control valve with the compressor operation during steady operation, and synchronizes the refrigerant control valve with the compressor operation during defrosting. The disadvantages of conventional examples A and B described above are simultaneously solved by closing the solenoid valve and opening the solenoid valve after defrosting is completed during the standby time until the cooling operation of the timer.

An embodiment of the present invention will be described below with reference to the drawings. 1 is a compressor, 2 is a condenser,
3 is a solenoid valve, 4 is a capillary tube, and 5 is an evaporator, each of which is connected by a pipe to form an annular cooling cycle. A thermostat 6 detects the temperature inside the refrigerator and opens and closes it, and controls the temperature inside the refrigerator by causing the compressor 1 to operate intermittently. A timer 7 integrates the operating time of the compressor 1 and periodically energizes the defrosting heater 8 to instruct defrosting of the evaporator 5, and is composed of a driving motor 7a and a switching contact 7b. . 9 is a bimetal thermostat for detecting the end of defrosting. The solenoid valve 3 is electrically connected in parallel with the timer drive motor 7a, with one end connected to the power supply via the thermostat 6, and the other end connected in series with the defrosting heater 8 to the power supply. connected to the side.

The operation of this configuration will be explained next. When the switching contact 7b of the timer 7 is on the NC side and the temperature control thermostat 6 is closed, the solenoid valve 3 is energized via the defrosting heater 8 (at this time,
(Due to the partial pressure caused by the resistance value, almost no voltage is applied to the defrost heater and the defrost heater does not generate heat.) 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 electricity 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 blocked by the solenoid valve 3 and the capillary tube 4
Since the flow into the evaporator 5 via the compressor 1 is eliminated, the heat load is prevented from flowing into the evaporator 5 when the compressor 1 is stopped. 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 7b is switched from NC to NO, and the compressor 1 is stopped. The defrosting heater 8 is energized to start defrosting. At this time, the solenoid valve 3 and the timer drive motor 7a are both short-circuited by the bimetal thermostat 9 and are not energized, the solenoid valve 3 is closed, and the timer drive motor 7a is stopped. As a result, the solenoid valve 3 prevents the high-pressure refrigerant from flowing into the evaporator 5 even during defrosting, so the refrigerant in the evaporator is raised to a predetermined temperature with a small amount, and the defrosting time is increased. It's short enough.

When the defrosting progresses further and the temperature of the evaporator 5 rises to a predetermined temperature, the bimetal thermostat 9 opens and the defrost heater 8 stops generating heat, and at the same time energizes the parallel circuit between the solenoid valve 3 and the timer drive motor 7a. is started, the solenoid valve 3 is opened, and the timer drive motor 7a starts operating. After a certain short time has elapsed, the switching contact 7b is switched from NO to NC by the action of the cam plate of the timer 7, and the compressor 1 is started to restart the cooling operation. Therefore, the operation graph of each part of the cooling system during and after defrosting is as shown in Figure 3, and the pressure change at that time is as shown by the solid line in Figure 4, which is the same as that of conventional example A until the end of defrosting. The pressure changes are exactly the same, and the differential pressure between the high and low pressures is large, but this is because the solenoid valve 3 is open during the waiting time until the switching contact 7b of the timer 7 switches to the NC side after defrosting. During this time, the high and low pressures are almost balanced through the capillary tube 4. Therefore, when the compressor 1 is restarted, it can be easily started under balance pressure as in the conventional example B.

As is clear from the above embodiments, the present invention provides a refrigerant control valve between a condenser and a pressure reducing device, opens and closes the refrigerant control valve in synchronization with the operation and stop of the compressor, and removes the evaporator. After the frost ends, the solenoid valve is opened during the standby time until the timer returns to cooling operation in preparation for restarting the compressor. When the compressor is stopped, the high-pressure side refrigerant is shut off by the refrigerant control valve and the pressure reducing device is shut off. Since the flow into the evaporator through the evaporator is prevented, the inflow of heat load can be prevented, and even during defrosting, the electromagnetic refrigerant control valve prevents the high-pressure side refrigerant from flowing into the evaporator, preventing evaporation. The defrosting time can be shortened by raising the temperature to a predetermined level with a small amount of refrigerant in the container. Furthermore, since the refrigerant control valve is opened even during the standby time until the compressor is restarted after defrosting, the high and low pressures are balanced through the pressure reducing device during this time, making it easier to restart the compressor.

Therefore, in conventional refrigeration equipment equipped with a solenoid valve, there were advantages and disadvantages depending on whether the solenoid valve was opened or closed during defrosting, but in the present invention, the refrigerant control valve is closed during defrosting. By taking advantage of the advantage of shortening defrosting time, after defrosting is completed, the refrigerant control valve is opened before the compressor, using the waiting time until cooling operation resumes, which occurs mechanically in a timer that does not use an electromagnetic relay. Since the advantage of improved compressor starting ability can be utilized, the advantages of both conventional examples can be combined by simply changing the connection circuit of the refrigerant control valve, and the practical utility is extremely high.

[Brief explanation of drawings]

Fig. 1 is a cooling cycle piping diagram used in the present invention and conventional example B, Fig. 2 is an electric circuit diagram corresponding to Fig. 1, and Fig. 3 is a defrosting time in the cooling system of the conventional example and the embodiment of the present invention. Operation graph of each part,
FIG. 4 is a graph of pressure changes in the cooling system corresponding to FIG. 1... Compressor, 2... Condenser, 3... Refrigerant control valve (electromagnetic valve), 4... Pressure reducing device (capillary tube), 5...
Evaporator, 6... thermostat, 7... timer, 8... defrost heater.

Claims (1)

[Claims] 1 A compressor, a condenser, a pressure reducing device, an evaporator, which are connected in sequence to form a ring; a thermostat that senses the temperature inside the refrigerator and controls the operation/stop of the compressor; and a defrost device that defrosts the evaporator. The cooling operation time of the frost heater and compressor is integrated, and when a certain period of time is reached, the compressor is stopped and the defrost heater is energized, and after the defrosting is finished, after a certain standby time, the compressor is switched to the cooling operation side. A refrigerant control valve is provided between the condenser outlet and the evaporator inlet, and the refrigerant control valve is opened and closed in synchronization with the operation and stop of the compressor. A refrigeration system configured to open the refrigerant control valve even during standby time of a timer.