JPH0263153B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a refrigerator equipped with a cooler that cools the inside of the refrigerator by a so-called fan cool method and a cooler that directly cools the inside of the refrigerator.

[Technical background of the invention and its problems]

In this type of refrigerator, the fan cooling cooler is defrosted by integrating the operating time of the compressor using a timer, and when this reaches a predetermined time value,
When the operation of the compressor is stopped, the defrosting heater is energized to forcibly heat the cooler. On the other hand, in this type of refrigerator, in order to prevent the problem of hot gas in the condenser flowing into the cooler and heating the inside of the refrigerator after the compressor stops operating,
Some refrigerators are equipped with a valve device between the condenser and the cooler that closes when the compressor stops operating, but if the defrosting method described above is adopted for a refrigerator with this configuration, the cooling system for direct cooling of the freezer compartment This causes a problem in that the temperature of the container rises to nearly 0°C, which adversely affects the heat-retaining food. In other words, when the compressor operation is stopped for defrosting, the valve device is also blocked at the same time, so the two-phase refrigerant is trapped in the fan cool cooler and the cooler for direct cooling of the freezer compartment. In this state, the fan cooling cooler is heated by the heater, so the liquid refrigerant therein evaporates, and the pressure inside both coolers increases. On the other hand, since the refrigerators for direct cooling are located in the freezer compartment and the ambient temperature is initially around -18℃, the gas refrigerant is condensed due to the increase in internal pressure, and the temperature inside the freezer compartment increases due to the heat released by this condensation. That's what I do. Furthermore, even if the compressor resumes operation after defrosting, the pressure inside the cooler increases considerably during defrosting, so the degree of pressure drop within the cooler and the degree of evaporation temperature decrease are slow, resulting in a high temperature state. The problem was that it lasted a relatively long time. To solve this problem, a cold storage agent such as potassium chloride is attached to the direct cooling cooler to prevent the temperature from rising, but this is disadvantageous in terms of cost.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a refrigerator that can prevent a temperature rise in a direct cooling cooler during defrosting of a fan cooling cooler.

[Summary of the invention]

The present invention has one refrigerant inlet connected to the outlet of the condenser and one refrigerant outlet connected to the suction of the compressor, and a direct cooling system provided in the refrigerator between the refrigerant inlet and the refrigerant outlet. A cooler group is provided, which connects a first cooler for indirect cooling and a second cooler for indirect cooling provided in a circulation path for circulating indoor air by a fan, and connects the outlet of the condenser to the cooling A valve device is provided in a passage connecting the refrigerant inlet of the device group, a defrosting heater is provided to heat the second cooler, and frost formation is detected by detecting frost formation on the second cooler. A frost detection means for outputting a signal is provided, a temperature sensor is provided for detecting the temperature of the second cooler, and the valve device is closed when the frost detection means outputs the frost detection signal. A first control means is provided for operating the compressor while the valve device is in a closed state, and a first control means for stopping the compressor and energizing the heater when the detected value of the sensor becomes a predetermined value or less. By providing the control means 2, the refrigerant in the cooler is suctioned and removed by the compressor prior to energizing the heater, and at that time, the compressor operation is stopped and the heater is energized by the fan coolant. It is characterized in that the temperature is controlled according to the temperature detected by a temperature sensor that detects the temperature on the refrigerant outflow side of the cooler.

[Embodiments of the invention]

An embodiment of the present invention will be described below based on the drawings. First of all, in Fig. 1, reference numeral 1 is a heat insulating foil of the refrigerator, and the inside is vertically divided into a freezing compartment 3 and a refrigerating compartment 4 by a partition wall 2. A first cooler 5 is arranged substantially horizontally. Furthermore, doors 6 and 7 for opening and closing the freezer compartment 3 and the refrigerator compartment 4 are pivotally installed throughout the heat insulating foil 1. On the other hand, the partition wall 2 has a cavity 8
is formed, and this cavity 8 is connected to ducts 9 and 1 formed at the back of the freezer compartment 3 and the refrigerator compartment 4, respectively.
0, and constitutes a circulation path 11 together with both ducts 9 and 10. A second cooler 12 is disposed in the cavity 8 of the circulation path 11, and in order to communicate the circulation path 11 with the freezer compartment 3 and the refrigerator compartment 4, there are holes on both upper and lower sides of the front part of the partition wall 2. First and second intake ports 13 opening into the freezer compartment 3 and the refrigerator compartment 4, respectively.
and 14 are formed, and both ducts 9 and 10 are formed with first and second exhaust ports 15 and 16 that open into the freezer compartment 3 and the refrigerator compartment 4, respectively. 1
Reference numeral 7 denotes a fan device disposed deep within the cavity 8, and is composed of a motor 18 fixed to the heat insulating box 1 and a fan 19 directly connected to the motor 18. 20 is a first damper device that closes the first intake port 13; 21 is a second damper device that closes the first exhaust port 15 by closing the lower end of the duct 9 on the side of the freezer compartment 3; Both damper devices 20
and 21 are electromagnets 20a and 2 shown in FIG.
It is configured to close using 1a as an operating source. 22 is a third damper device that closes the second exhaust port 16, and this is also an electromagnet 22a shown in FIG.
The closing operation is performed using the operating source as the operating source.

Next, in Figure 2 showing the refrigeration cycle, 23
is a rotary compressor, and this compressor 2
The discharge port 3 is connected to a capacitor 24.
The first cooler 5 and the second cooler 1
2 are connected in series to form a cooler group, and the refrigerant inlet of the first cooler 5, which is one refrigerant inlet of this cooler group, is connected to the outlet of the condenser 24 via the capillary tube 26, and the cooling A check valve 27 connects the refrigerant outlet of the second cooler 12, which is one refrigerant outlet of the device group.
It is connected to the suction port of the compressor 23 via. 25 is a solenoid valve as a valve device, which is located in a passage connecting the outlet of the condenser 24 and the refrigerant inlet of the first cooler 5 which is the refrigerant inlet of the cooler group;
For example, it is provided between the outlet of the condenser 23 and the inlet of the capillary tube 26. The electromagnetic valve 25 is configured to open when energized. Further, a defrosting heater 28 is attached to the second cooler 12. 29 is the second cooler 12
This is a temperature sensor placed near the refrigerant outlet to detect the temperature on the refrigerant outlet side of the refrigerant, and the signal (detected temperature) from this temperature sensor 29 is transmitted to the first and second points shown in FIG. 6 during defrosting. The microcomputer 30 as a control means compares the temperature with a plurality of preset reference values, and controls the motor 18, the electromagnets of the first and second damper devices 20 and 21, and the compressor according to the temperature detected by the temperature sensor 29. 2
3 and the heater 28 are controlled to be turned on and off.

This refrigeration cycle is controlled by a control circuit shown in FIG. In FIG. 6, 31 and 32 are a freezing room temperature detection switch and a refrigerating room temperature detection switch, which are connected in series with resistors 33 and 34 between the power supply and ground, respectively. Further, the temperature sensor 29 is connected in series with a resistor 35 between the power source and ground. Signals from the freezing room temperature detection switch 31, the refrigerator room temperature detection switch 32, and the temperature sensor 29 are input to the microcomputer 30. Reference numeral 36 denotes a timer, which integrates the operating time (energization time) of the compressor 23 and provides a time-up signal to the microcomputer 30 when the integrated time reaches, for example, 8 hours. That is, when the cumulative operating time of the compressor 23 reaches 8 hours, the second
It is known from experience that frost accumulates on the cooler 12 to the extent that it requires defrosting. Therefore, timer 3
6 is not used to directly detect frost adhering to the second cooler 12, but functions as a frost detection means, and when the timer 36 measures the cumulative time of 8 hours, a frost detection signal is generated. It is configured to give a time-up signal to the microcomputer 30. 37 to 42 are relays, and these exciting coils 37a to 42a are connected between the power supply and the collectors of NPN transistors 43 to 48, the emitters of each of these transistors 43 to 48 are connected to the ground, and the bases are connected to the ground. It is connected to the output port of the microcomputer 29. Therefore, when a high level signal is input from the microcomputer 30 to the bases of the transistors 43 to 48, the transistors 43 to 48 are turned on and the relay coils 37a to 42a are energized. The relay switches 37b to 42b of the respective relays 37 to 42 connect the compressor 23, the motor 18 of the fan device 17, the solenoid valve 25, and the electromagnets 20a and 20 of the first and second bumpers 20 and 21 to the commercial AC power source.
Parallel circuit of a, electromagnet 22 of third damper 22
a, connected in series with the heater 28; In the refrigerator configured as described above, when the temperature inside the freezing compartment 3 reaches a predetermined temperature or higher, the freezing room temperature detection switch 3 is activated.
1 turns on. Then, microcomputer 3
0 outputs a high level signal to the bases of transistors 43, 45, and 44, so excitation coil 37
a, 39a, and 38a are energized. This results in
Since the relay switches 37b, 39b, and 38b are turned on, the compressor 23, the solenoid valve 25, and the motor 18 for the fan 19 are energized and started. The refrigerant compressed by the compressor 23 and liquefied by the condenser 24 flows into the first and second coolers 5 and 12 via the electromagnetic valve 25 and the capillary tube 26, and then passes through the check valve 27. The air is sucked into the compressor 23 again and compressed, thus circulating. On the other hand, since the first to third damper devices 20 to 22 are both cut off and in the open state shown by the strong lines in FIG.
And the air in the refrigerator compartment 4 flows through the first and second intake ports 1
3 and 14 into the circulation path 11, and is cooled by the second cooler 12. The cooled air is divided into both ducts 9 and 10, and the air is divided into the first and second ducts, respectively.
Freezer compartment 6 and refrigerator compartment 4 from the discharge ports 15 and 16 of
and eventually the first and second intake ports 13.
and 14, and is sucked into the circulation path 11 again. Therefore, the freezer compartment 3 is cooled by both the first cooling air 5 and the cold air from the second cooler 12, and the refrigerator compartment 4 is cooled by the cold air from the second cooler 12. Then, when the inside of the refrigerator compartment 4 is cooled to a predetermined temperature, the refrigerator room temperature detection switch 32 is turned on. Then, the microcomputer 30 outputs a high level signal to the base of the transistor 47, so that the excitation coil 41a is energized. As a result, the relay switch 41b is turned on, so that the third damper device 22 is energized and enters the closed state shown by the two-dot chain line in FIG. After this, cold air is supplied only into the freezer compartment 3, and cooling of the freezer compartment 3 is continued. When the temperature inside the freezing compartment 3 becomes below a predetermined temperature, the freezing room temperature detection switch 31 is turned off. Then, the microcomputer 30 sets the bases of the transistors 43, 445, and 44 to a low level state, so that the excitation coils 37a and 39
a, 38a are cut off. This turns off relay switches 37b, 39b, and 38b, so
The compressor 23, the solenoid valve 25, and the motor 18 are de-energized. When the electromagnetic valve 25 is cut off and blocked, the refrigerant in the condenser 24 is trapped in the current flowing from the check valve 27 to the electromagnetic valve 25, so the hot gas in the condenser 24 flows into the coolers 5 and 12. If it were to flow into the water and heat it, the same problem would not occur. When the temperature inside the freezer compartment 3 rises to a predetermined temperature, the freezing room temperature detection switch 31 is turned on and the operation as described above is restarted. Normally, the freezing room temperature detection switch 3 is set as shown above.
1 is turned on and off (this operating state is hereinafter referred to as normal control operation).

Now, frost gradually adheres to the second cooler 12 due to the normal control operation. This frost is Compressa 23
A timer 36 adds up the operating time, and defrosting is performed every time the added time reaches, for example, 8 hours. That is, as shown in the time chart of FIG. 3, when the cumulative operating time of the compressor 23 reaches 8 hours (this time point is indicated by A in FIG. 3), the timer 36 outputs a time-up signal. As a result, the microcomputer 30 brings the base of the transistor 45 to a low level, thereby cutting off the power to the excitation coil 39a. This turns off the relay switch 39b, so only the solenoid valve 25 is cut off and closed.
In this state, the compressor 23 continues to operate. Due to this operation, both coolers 5 and 12 receive the suction action of the compressor 23 without being supplied with refrigerant from the condenser 24 side, so that the liquid refrigerant inside evaporates and becomes a low pressure state. Then, due to the evaporation of the liquid refrigerant in this low pressure state, the second cooler 1
When the refrigerant outflow side of No. 2 becomes below a predetermined temperature (this point is indicated by B in Fig. 3), this is detected by the temperature sensor 29.
is detected, and based on this detection signal, the microcomputer 30 sets the bases of the transistors 43 and 44 to a low level state, and the excitation coils 37a and 38a
At the same time, a high level signal is output to the bases of the transistors 46 and 48, and the excitation coil 4 is turned off.
0a and 42a are energized. As a result, the relay switches 37b and 38b are opened and the relay switches 40b and 42b are turned on, so that the motor 18 for the compressor 23 and the fan 19 is cut off, and the first and second damper devices 20 and 21 At the same time, the heater 28 is energized. Thereby, the second cooler 12 is heated by the heater 28 and defrosted. In this case, since the insides of both coolers 5 and 12 are in a low pressure state with no liquid refrigerant, the problem that the amount of gas refrigerant inside the coolers 5 and 12 increases due to the heat generated by the heater 28 and becomes high pressure does not occur. Therefore, the problem of heat being radiated into the freezer compartment 3 due to the condensation effect performed in the first cooler 5 does not occur. Further, since the first and second damper devices 20 and 21 are energized and in a closed state, the warm air inside the cavity 8 does not flow into the freezing chamber 3. When the frost completely melts and the refrigerant outlet side of the second cooler 12 rises to a predetermined temperature (this point is indicated by C in FIG. 3), the temperature sensor 29 detects this and sends this detection signal. Based on microcomputer 30
outputs a high level signal to the bases of transistors 43 and 45 to energize excitation coils 37a and 39a, and also brings the base of transistor 48 to a low level state to disconnect power from excitation coil 42a. As a result, relay switches 37b, 39b
is closed, and the relay switch 42b is opened, so that the compressor 23 and the solenoid valve 25 are energized, and the heater 28 is cut off. Then, when the refrigerant is supplied to the second cooler 12 and the temperature on the outflow side of the refrigerant falls below a predetermined temperature (this point is indicated by D in FIG. 3), the microcomputer 30 activates the transistor In order to output a high level signal to the base of transistor 44 and bring the base of transistor 46 to a low level state, relay coil 38a is energized and relay coil 40a is deenergized. As a result, the relay switch 38b is turned on and the relay switch 40b is turned off, so that the fan 19
The first and second motors 18 are energized, and the first and second
The damper devices 20 and 21 are cut off, thus ending the defrosting control period and returning to normal control operation. By the way, Figure 4 shows the first phase in the defrosting control period A to D.
This shows the results of experimentally measuring the temperature change of the first cooler 5. As is clear from this figure, the temperature of the first cooler 5 increases significantly during the defrosting control period and reaches nearly 0°C. There is no risk of adverse effects on food preservation.

By the way, the time during which the compressor 23 is operated with the solenoid valve 25 closed during defrosting preferably changes depending on the amount of refrigerant in the first and second coolers 5 and 12. Because both coolers 5
And if the amount of gas in 12 becomes less than a certain amount,
This is because even if the compressor 23 is operated any further, the temperature rise prevention drop of the first cooler 5 will not change. Therefore, as shown in FIG.
Focusing on the fact that the temperature change on the second cooler 12 and the refrigerant outlet side matches the pressure change that is correlated with the amount of refrigerant, a temperature sensor 29 is provided to detect the temperature on the refrigerant outlet side of the second cooler 12. Since the compressor 23 is stopped based on the detected temperature, the compressor 23 is not operated more than necessary, and power saving can be achieved.

Although the above embodiment has been described using a rotary compressor, a reciprocating compressor having a built-in valve corresponding to the check valve 27 may also be used. Also, the number of coolers is not limited to two, but may be three or more, and various changes are possible, such as a second cooler for fan cooling may be used to cool only the refrigerator compartment or freezer compartment. .

〔Effect of the invention〕

As is clear from the above description, the present invention provides the following excellent effects. That is, when defrosting the second cooler for fan cooling, the compressor is first allowed to continue operating with the valve device closed, and then the compressor is stopped and the defrosting heater is energized. The second cooler can be heated in a low-pressure state without liquid refrigerant, and therefore, it is possible to prevent the inconvenience caused by condensation in the first cooler for direct cooling, which causes the temperature inside the refrigerator to rise significantly. . In addition, a temperature sensor is provided to detect the temperature on the refrigerant outlet side of the second cooler, and the compressor operation stop and heater energization are controlled according to the temperature detected by this temperature sensor. It is possible to save power by not operating for more than an hour, and the configuration is simple because it is controlled by one temperature sensor.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a longitudinal cross-sectional side view of the upper half of the refrigerator, Fig. 2 is a refrigeration cycle diagram, Fig. 3 is a time chart, and Fig. 4 is a diagram of the refrigeration cycle during defrosting. FIG. 5 is a diagram showing the relationship between the refrigerant outlet temperature and the internal refrigerant pressure of the second cooler, and FIG. 6 is a control circuit configuration diagram. In the figure, 3 is a freezer compartment, 5 is a first cooler, 11 is a circulation path, 12 is a second cooler, 19 is a fan, 2
3 is a rotary compressor, 24 is a capacitor,
25 is a solenoid valve (valve device), 28 is a heater, 29 is a temperature sensor, 30 is a microcomputer (first
to third control means), and 36 is a timer (frost formation detection means).

Claims (1)

[Claims] 1 One refrigerant inlet connected to the outlet of the condenser and one refrigerant outlet connected to the suction inlet of the compressor, and a direct cooling nozzle provided in the refrigerator between the refrigerant inlet and the refrigerant outlet. a cooler group formed by connecting a first cooler and a second cooler for indirect cooling provided in a circulation path for circulating indoor air by a fan; and a refrigerant between the outlet of the condenser and the cooler group. A valve device provided in a passage connecting the inlet, a defrosting heater that heats the second cooler, and detects frost formation on the second cooler and outputs a frost detection signal. a temperature sensor for detecting the temperature of the second cooler; and a temperature sensor for detecting the temperature of the second cooler; and a temperature sensor that closes the valve device when the frost detection device outputs a frost detection signal; a first control means for operating the compressor in a closed state; and a second control means for stopping the compressor and energizing the heater when the detected value of the sensor becomes less than or equal to a predetermined value. A refrigerator that is equipped with