JPS6340769Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigerator equipped with a freezing compartment, and more particularly to a refrigerator equipped with a cooler at a lower temperature than a freezing cooler in the freezing compartment.

In general, in a so-called direct cooling type refrigerator in which a freezing cooler is formed into a substantially rectangular box shape and the inside thereof is used as a freezing chamber, the freezing chamber is cooled almost uniformly from almost the entire inner surface of the freezing cooler. ing. However, during cooling operation, the box adheres to almost the entire inner surface of the refrigeration cooler, and as the box acts as an insulator, the cooling efficiency decreases, and there is also the drawback that frost may also adhere to the contents such as ice cube trays. .

Additionally, when performing defrosting operation, the power is temporarily turned off to stop the cooler operation, or the frosted walls are heated using a heater, but this means heating the entire freezer compartment. It has the disadvantage that it can even melt frozen food indoors. To compensate for this drawback, frozen items in the freezer compartment are temporarily stored in the refrigerator compartment, but this method has drawbacks such as being time-consuming.

The present invention was made to solve the various drawbacks mentioned above, and the compressor, condenser, first capillary tube, first evaporator, second evaporator, and third evaporator are arranged in an annular shape in this order. A refrigerant circuit connected to the
a bypass circuit branched from the inflow side of the first evaporator of this circuit, connected to one end of a second capillary tube, and the other end connected to the outflow side of the second evaporator. The second evaporator and the third evaporator cool the freezing compartment, the first evaporator cools the refrigerator compartment, and the second evaporator is formed in close contact with the peripheral wall of the freezing compartment. The third evaporator is disposed in the freezing chamber apart from the chamber wall to provide a refrigerator in which frost can be concentrated on the third evaporator and the entire wall of the freezing chamber can be defrosted.

Embodiments of the refrigerator according to the present invention will be described below with reference to the drawings. In FIG. 1, the inside of a refrigerator body 1 is divided into two upper and lower chambers 2a and 2b, with the upper chamber 2a serving as a freezing chamber and the lower chamber 2b serving as a refrigerating chamber. These chambers 2a, 2b and doors 17, 18 are each insulated with a built-in foam material such as styrofoam. The refrigerator main body 1 has a machine room space P in the lower part thereof, and a compressor 3 and an evaporating dish 4 are disposed in the space P. A compressed gas discharge port 3a of the compressor 3 is connected to one end of a condenser 5 as shown in FIG. This condenser 5 is fixed to the back wall of the refrigerator body 1 with a support 6. (Figure 1)
Further, as shown in FIG. 4, a first capillary tube 7 is connected to the other end, and this capillary tube 7 is disposed in the upper back of the refrigerator compartment 2b via a solenoid valve 11. It is connected to one end of the first evaporator 8 . The other end of this evaporator 8 is the freezer compartment 2a.
The second evaporator 10 is connected to one end of a second evaporator 10 that cools the inside of the freezer compartment, which is formed in close contact with the peripheral wall of the freezer. The other end of the second evaporator 10 is connected to one end of the third evaporator 12, and the other end is connected to the suction port 3b of the compressor 3.

Further, a third evaporator is branched from the upstream side of the electromagnetic valve 11 in parallel with the first evaporator 8 and the second evaporator 10.
Bypass circuit 2 that joins the upstream side of the evaporator 12 of
1 is connected. This bypass circuit 21 has a second
A capillary tube 22 is connected thereto. The third evaporator 12 is disposed in front of the rear wall of the freezer compartment 2a at a distance so as not to contact the inner wall, and has a meandering pipe arranged at an angle as shown in FIG.
A dew pan 13 is provided on the descending end side 12a of this pipe. Further, the front surface of the third evaporator 12 is separated from the third cooler 12 by a door 17 of the freezer compartment 2a.
It is covered with a blinding plate 14 so that it cannot be seen directly from the side. The front and back of this blind board 14 are communicated indoors. Furthermore, an electric heater 15 is provided in close contact with the pipe wall of the third evaporator 12, as shown in FIG. Further, pipes 16a and 16b are connected to the dew pans 9 and 13, respectively, and these pipes 16a and 16b communicate with the drain pipe 16 to guide the liquid accumulated in the pans 9 and 13, respectively, to the evaporation pan 4. There is. In the refrigerator compartment 2b, shelves 19 are provided which are partitioned vertically into desired levels.

However, if R-12 is used as the refrigerant in the above refrigerator, if the solenoid valve 11 is open while the compressor 3 is in operation, the refrigerant that has passed through the condenser 5 and the capillary tube 7 will flow into the second capillary. Since the tube 22 acts as a resistance, most of the liquid flows into the first evaporator 8 and a part of the liquid evaporates to cool the inside of the refrigerator compartment 2b, and then flows into the second evaporator 10 of the freezing compartment 2a and evaporates. It cools the inside of the freezer compartment 2a, then flows into the third evaporator 12, evaporates, cools the freezer compartment, and returns to the compressor 3. At this time, the pressure of the refrigerant flowing through the first evaporator 8, second evaporator 10, and third evaporator 12 is approximately the same, approximately 1.2 Kg/cm ² a, so the surface temperature of each evaporator varies. will be approximately the same, about -25℃. Therefore, the moisture present in the freezer compartment 2a comes to form frost on the surfaces of the second evaporator 10 and the third evaporator 12, respectively.

On the other hand, when the solenoid valve is closed, the refrigerant that has passed through the condenser 5 and the capillary tube 7 is transferred to the second capillary tube 2 provided in the bypass circuit 21.
2 is further reduced in pressure, flows into the third evaporator 12 of the freezing compartment 2a at a pressure of about 1.02 kg/cm ² a, evaporates, cools the freezing compartment 2a, and returns to the compressor 3. At this time, no refrigerant flows into the first evaporator 8 and the second evaporator 10. Therefore, the surface temperature of the second evaporator 10 forming the inner wall of the freezer compartment 2a is -25°C or higher, whereas the surface temperature of the third evaporator 12 is higher than -25°C.
In this case, the refrigerant has an even lower evaporation temperature (approximately -30°C), and has a temperature difference of 5°C or more lower than that in the second evaporator 10. At this time, the frost adhering to the second evaporator 10 gradually sublimates into steam, which moves to the third evaporator 12, refreezes, and adheres in a concentrated manner.

Generally, frost that forms in a refrigerator is thought to be caused by moisture inside the refrigerator being cooled by the cooler and freezing.

In the refrigerator of the present invention, when the temperature of the refrigerator compartment or the freezer compartment is high, the solenoid valve 11 is opened and the compressor 3
The moisture generated when the door 17 of the freezer compartment 2a is opened and closed and the outside air and the freezer room air are exchanged forms frost on the second and third evaporators 10 and 12 to the same thickness. become. On the other hand, if the temperature in the refrigerator compartment becomes low and the solenoid valve is closed by the signal from the temperature sensor 25 attached to the first evaporator 8, only the third evaporator 12 will be cooled as described above. The frost adhering to the evaporator 10 is removed from the third evaporator 1.
It can be collected in 2. When the temperature of the freezer compartment 2a further decreases, the operation of the compressor 3 is stopped by a signal from the temperature sensor 26 attached to the freezer compartment 2a.

The amount of frost movement from the second evaporator 10 to the third evaporator 12 when the solenoid valve is closed is given by the following equation.

G=ρD1/1−ω・dw/dy…(1) Here, G: Movement amount of frost (g/m ³ h), ρ: Specific weight of moist air (Kg/m ³ ), D: Diffusion coefficient, ω: absolute humidity of humid air (Kg/m ³ ), y: length (m).

Now the surface temperature of the second evaporator 10 Ts ₁ = -25°C
By changing the surface temperature Ts ₂ of the third evaporator 12, △
The frost formation performance based on T=Ts ₁ -Ts ₂ is shown in FIG. 5 using equation (1). From this characteristic, if the air side heat transfer area of the third evaporator 12 is A = 0.04 ^m2 , and the temperature difference is △T = 5°C, the third
The amount of frost on the evaporator 12 is approximately 50 g, assuming that the solenoid valve is closed for 10 hours per day.
Normally, the amount of defrosting required per day is about 15g in a refrigerator equipped with a freezer compartment with an internal volume of about 53 cm, so if the low-temperature evaporator of the present invention is used to create a temperature difference of △T = 5°C or more, the amount of defrosting in the freezer compartment This means that all of the frost generated within 2a can be concentrated in one place, that is, on the surface of the third evaporator 12.

Therefore, when the surface of the third evaporator 12 reaches a predetermined thickness of frost, if the electric heater 15 shown in FIG. flows down, flows into the evaporating dish 4, and evaporates. At this time, if the electric heater 15 is set so that the power is turned off after the defrosting of the third evaporator 12 is completed by an appropriate amount, the third evaporator 12
Since it is provided away from the inner wall of the room a, it is possible to defrost the room without heating the room. Automation can be achieved by providing a thermistor in this third evaporator 12 to control the defrosting operation.

As is clear from the above explanation, the present invention provides a capillary tube in the bypass circuit and adds resistance to the bypass circuit, so that when the solenoid valve is open, the refrigerant is transferred between the first evaporator and the second evaporator. This makes it possible to flow into the flow path of the evaporator, thereby increasing the cooling effect of the third evaporator. By providing the third evaporator whose temperature is lower than that of the second evaporator, it is possible to reduce frost adhering to the wall surface without reducing the cooling area of the inner wall of the freezer compartment. In addition, it is possible to improve the cooling efficiency of the direct-cooled refrigerator, and it is also possible to prevent frost from adhering to objects to be cooled such as ice cube trays, thereby facilitating the removal of stored objects. Also the third
Since the evaporator is located away from the chamber wall, it is easy to maintain the temperature difference between the two coolers.

Furthermore, according to the refrigerator of the present invention, defrosting is possible by heating the third evaporator without heating the wall of the freezer compartment, so there is no need to take the cooled material outside for defrosting. In addition, problems that have been difficult with conventional direct cooling refrigerators, such as automatic defrosting when necessary, can be solved with an extremely simple configuration.

In addition, according to the present invention, since only the frost adhering to the third evaporator is heated, the heat capacity is small, and the heat dissipation area of the third evaporator is small compared to the inner wall area, so the heat dissipation loss is also small and the consumption is small. This has the effect of reducing power consumption.

Furthermore, the third evaporator is located in front of the rear wall, which simplifies the arrangement of the condensation pan.Furthermore, the freezer compartment of direct-cooled refrigerators generally does not have a cooler on the back, so This contributes to improving the cooling effect as the area increases, and has the effect that the internal volume of the freezer compartment hardly decreases.

In the embodiment of the present invention, an electric heater is used as a heat source for defrosting. However, the present invention is not limited to this example. Hot gas or other suitable heat sources may be used.
It goes without saying that defrosting is possible by using an OFF cycle or the like.

[Brief explanation of the drawing]

Figures 1 to 5 are for explaining one embodiment of the refrigerator according to the present invention. Figure 1 is a longitudinal sectional view of the refrigerator, and Figure 2 is a partial cutaway from the rear of Figure 1. A perspective view showing the interior of the notch, FIG. 3 is an enlarged perspective view of the main part of FIG. 2 cut along X-Y, and FIG. 4 is a circuit diagram showing the refrigeration cycle of the refrigerator. , FIG. 5 is a characteristic diagram showing the change characteristics of the amount of movement of frost with respect to the temperature difference. In addition, 1 is a refrigerator main body, 2a is a freezer compartment, 2b is a refrigerator compartment, 10 is a second evaporator, 12 is a third evaporator, 11 is a solenoid valve, and 21 is a bypass circuit.

Claims (1)

[Scope of utility model registration request] a compressor, a condenser, a first capillary tube,
A refrigerant circuit in which a first evaporator, a second evaporator, and a third evaporator are connected in an annular manner in this order, and a second capillary tube branched from the inflow side of the first evaporator of this circuit. one end and the other end to the second
a bypass circuit connected to the outlet side of the evaporator, the second evaporator and the third evaporator cool the freezing compartment, the first evaporator cools the refrigerator compartment, and A refrigerator characterized in that the second evaporator is formed in close contact with a peripheral wall of the freezing chamber, and the third evaporator is arranged in the freezing chamber apart from the chamber wall.