JPS6255594B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a defrosting device for a refrigerator, and more particularly to a hot gas bypass defrosting device.

Generally, when frost adheres to the surface of the evaporator coil, the frost inhibits heat transfer, resulting in a significant reduction in the cooling ability of the coil.

Various defrosting means have been devised in the past in order to prevent a decrease in cooling capacity due to such frosting.

The schematic configuration of a conventional device generally known as a refrigerator equipped with a defrosting device using hot gas is shown in the third section.
As shown in the figure. In the figure, 31 is a compressor, 32 is an air-cooled condenser, 33 is a liquid receiver, 34 is an expansion mechanism, and 35
36 is a flow divider, 36 is an evaporator, and 37 is an accumulator. These are connected by a refrigerant pipe 38 to constitute a refrigeration cycle, and the discharge pipe 38' of the compressor 31 in the refrigerant pipe and the expansion mechanism 3
A hot gas bypass pipe 40 with a hot gas solenoid valve 39 is provided between the refrigerant pipe 38 between the refrigerant pipe 38 and the flow divider 35, and a four-way valve (not shown) is switched during defrosting, and the hot gas solenoid valve 39 is opened. In order to defrost the compressor discharge gas (hot gas) by guiding it to the evaporator 36 via the hot gas bypass piping 40 without introducing it into the condenser 32, and heating the frost adhering to the evaporator coil surface. The composition is known.

However, in such a conventional simple hot gas system, the refrigerant accumulated from the liquid outlet of the condenser 32 to the expansion mechanism 34 does not contribute to the defrosting process, so the amount of refrigerant circulation during defrosting is limited.
As a result, defrosting took a long time and was difficult to defrost. This can be easily understood from the fact that the heat source for hot gas defrost is determined by the compressor input (in other words, the amount of refrigerant circulated), and the defrost performance is influenced by the magnitude of the compressor input.

In view of such circumstances, the present invention provides a hot gas bypass pipe between the refrigerant pipe between the expansion mechanism and the evaporator and the four-way valve, and also provides a hot gas bypass pipe between the compressor suction line and the four-way valve. By providing gas suction piping and configuring the condenser inlet pipe to communicate with the compressor suction line via the four-way valve and gas suction piping during defrost, the amount of refrigerant circulation during defrost can be controlled using a simple hot gas system. The purpose of the present invention is to provide a defrosting device for a refrigerator that accelerates defrosting, shortens defrosting time, and facilitates defrosting in winter.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

Fig. 1 is a refrigerant system diagram showing a defrosting device for a refrigerator according to the present invention, in which 1 is a compressor, 2 is a four-way valve with a built-in slide valve (not shown), and 3 is an air-cooled condenser. 4 is a liquid receiving product, 5 is an expansion mechanism, 6 is a flow divider,
7 is an evaporator, 8 is an accumulator, and these are connected by refrigerant pipes 9 to 16 to form a circulation refrigeration cycle. In addition, 17 is a condenser fan,
18 is an evaporator fan.

The four-way valve 2 has four ports 19, 20, 2.
1 and 22, 19 is a regular inlet, 21 is a regular outlet, and 20 and 22 are inlets and outlets. During normal refrigeration operation, the normal inlet 1 is shown as a solid line in Figure 1.
9 and the inlet/outlet 20 communicate with each other, and the normal outlet 21
During defrosting, the normal inlet 19 and the inlet/outlet 22 communicate with each other, and the inlet/outlet 20 and the normal outlet 21 communicate with each other, as shown by dotted lines in the figure, during defrosting.

One inlet/outlet 2 of the four-way valve 2 configured in this way
2, and the refrigerant pipe 1 between the expansion mechanism 5 and the flow divider 6
3, a hot gas bypass pipe 24 with a check valve 23 interposed therebetween is provided. The check valve 23 prevents the refrigerant from bypassing the evaporator 7 during normal operation. That is, the refrigerant is prevented from flowing into the refrigerant pipe 15 via the hot gas bypass pipe 24 and the four-way valve 2.

In addition, a gas suction pipe 26 is provided between the regular outlet 21 of the four-way valve 2 and the compressor suction line 25, specifically, the refrigerant pipe 15, and the slide valve of the four-way valve 2 is switched during defrosting. When the inlet pipe 3a of the condenser 3 is connected to the inlet/outlet port 2 of the four-way valve 2,
0, it is configured to communicate with the compressor suction line 25, that is, the refrigerant pipe 15, via the regular outlet 21 and the gas suction pipe 26.

The present invention is constructed as described above, and its operation will be explained below.

First, normal refrigeration operation will be described.
During this normal operation, the four-way valve 2 is switched so that its normal inlet 19 and outlet 20 and its normal outlet 21 and outlet 22 communicate with each other, as shown by solid lines in FIG. Now, when the compressor 1 is driven, the gas refrigerant compressed by the compressor 1 to a high temperature and high pressure passes through the normal inlet 19 and the outlet 20 of the four-way valve 2 to the condenser 3 as shown by the solid arrow in FIG. The liquid refrigerant enters, undergoes heat exchange, and is liquefied through the liquid receiver 4 and reaches the expansion mechanism 5, where the liquid refrigerant is throttled and expanded to a low pressure and flows into the evaporator 7 via the flow divider 6. The refrigerant enters the refrigerant, absorbs heat from the outside, is vaporized and becomes a gas refrigerant, and is further sucked into the compressor 1 via the accumulator 8. During normal operation, gas refrigerant enters the condenser from the top (condenser inlet pipe) and flows out from the bottom as liquid refrigerant.

Note that during such normal operation, the check valve 23 prevents the refrigerant from bypassing the evaporator 7.

Next, we will discuss defrost operation. During this defrost operation, the four-way valve 2 is switched so that its normal inlet 19 and outlet 22 and its normal outlet 20 and outlet 21 communicate with each other, as shown by dotted lines in FIG. Now, the gas refrigerant (hot gas) that has been compressed by the compressor and has become high temperature and high pressure passes through the normal inlet 19, outlet 22 and hot gas bypass pipe 24 of the four-way valve 2, as shown by the dotted arrow in FIG. At this point, the frost adhering to the evaporator coil surface is heated and defrosted.

Also, during defrosting, the condenser inlet pipe 3a is communicated with the refrigerant pipe 15 in the compressor suction line 25, specifically the confluence point A, via the inlet/outlet 20 of the four-way valve 2, the regular outlet 21, and the gas suction pipe 26. hand,
The circuit from the condenser inlet pipe 3a to point A becomes low pressure, and the refrigerant accumulated in the condenser 3 during normal operation is heated by the condenser ambient temperature, that is, the outside air temperature (outside air temperature>inside temperature) during defrosting. The refrigerant vapor that is boiling is transferred to the inlet/outlet 20 of the four-way valve 2, the regular outlet 21, and the gas suction pipe 26.
The refrigerant flows through the refrigerant to the confluence point A, where it merges with the refrigerant from the evaporator 7 during defrosting.

Since the refrigerant that has reached the confluence point A through the gas suction pipe 26 has a higher temperature than the refrigerant from the evaporator 7 during defrost, the temperature of the two converged refrigerants increases;
As the concentration becomes high, the amount of refrigerant circulated increases by the amount of refrigerant that passes through the gas suction pipe 26 and reaches the confluence point A. As a result, the compressor input is increased compared to the conventional simple hot gas system, so a sufficient defrost heat source can be secured.

Note that the boiling in the condenser 3 has a relatively short defrost time (for example, about 15 minutes), so
During this time, the liquid refrigerant in the condenser 3 does not run out and continues.

Further, since the boiling refrigerant vapor flows into the inlet of the accumulator 8, liquid refrigerant does not accumulate in the accumulator 8. That is, the refrigerant involved in defrosting does not liquefy during the process.

Therefore, the amount of refrigerant circulated during defrosting can be increased, defrosting can be accelerated, the defrosting time can be shortened, and winter defrosting can be easily performed. It is recommended that the condenser fan 17 be turned off during defrosting in the summer.

FIG. 2 is a refrigerant system diagram showing another embodiment, in which a constant pressure expansion valve 27 of the gas suction pipe 26 is interposed,
It is constructed so as not to increase the suction pressure of the compressor 1 unnecessarily, and the set value of the constant pressure expansion valve 27 when R-22 is used as the refrigerant is 4.0 to 4.5K/
It is recommended to set it to ^cm2 .

With this configuration, since the ambient temperature of the condenser 3 is relatively high, boiling in the condenser 3 becomes intense during defrosting, but the constant pressure expansion valve 27 can reduce the refrigerant supply pressure to the compressor 1. It is possible to maintain the compressor 1 properly and prevent the compressor 1 from overloading. Furthermore, since the constant pressure expansion valve 27 prevents an excessive increase in the compressor suction pressure and prevents the high pressure from becoming excessive, a safety valve or a high pressure switch (not shown), etc., are unnecessary and can be cut off immediately. Therefore, the operation of the compressor 1 will not be interrupted. In this case, the condenser fan is always operated, but the refrigerant supply pressure to the compressor 1 is properly controlled, and under such conditions, maximum heat source absorption for defrosting can be achieved. Further, when the constant pressure expansion valve 27 is provided, it is not necessary to provide a check valve in the hot gas bypass piping 24.
This means that the set value of the constant pressure expansion valve 27 is, for example,
For example, the resistance of the evaporator 7 for 4.0 to 4.5K/cm ² is
This can be easily understood from the fact that it is 0.5K/cm ² .

As described in detail above, the present invention connects the condenser 3, the expansion mechanism 5, the evaporator 7, and the compressor 1 in order through refrigerant piping, and also includes the four-way valve 2, which connects the compressor to the compressor. A regular inlet 19 in the discharge pipe 9 and an evaporator 7
A regular outlet 21 is provided in the refrigerant pipe between the and the compressor 1,
One inlet/outlet 22 is connected to the refrigerant piping between the expansion mechanism 5 and the evaporator 7 via a check valve 23 that prevents the flow of refrigerant from the piping side to the four-way valve 2 side, and the other is connected to the condenser inlet 3a. Since the inlet and outlet ports 20 are configured to communicate with each other, the amount of refrigerant circulated during defrosting is increased compared to that of the conventional simple hot gas method, and the effect of accelerating defrosting and shortening the defrosting time is increased. be.

Further, as shown in the embodiment, the condenser fan 17 is provided in the condenser 3, and a constant pressure expansion valve 27 is provided between the evaporator 7 and the compressor 1 and the normal outlet 21 of the four-way valve 2. If the condensing fan 17 is operated during defrosting, even if boiling in the condenser 3 intensifies during defrosting due to the operation of the condenser fan 17, the constant pressure expansion valve 27 will cause the compressor 1 to The refrigerant supply pressure to the compressor 1 can be maintained at an appropriate level, and overload of the compressor 1 can be prevented.

Furthermore, since the constant expansion valve 27 prevents an excessive increase in the compressor suction pressure and prevents the high pressure from becoming excessive, a safety valve or a high pressure switch (not shown), etc., are unnecessary and can be cut off immediately. This means that there will be no interruption in compressor operation.

Furthermore, the operation of the condenser fan 17 takes in sufficient energy for defrosting from the outside air, so that defrosting can be completed quickly.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant system diagram showing a defrosting device for a refrigerator according to the present invention, Fig. 2 is a refrigerant system diagram showing another embodiment, and Fig. 3 is a refrigerant system diagram for explaining the drawbacks of the conventional example. It is. 1... Compressor, 2... Four-way valve, 3... Condenser,
3a... Condenser inlet pipe, 5... Expansion mechanism, 7...
Evaporator, 9... Compressor discharge pipe, 19... Regular inlet, 20, 22... Inlet/outlet, 21... Regular outlet,
24...Hot gas bypass piping, 25...Compressor suction line, 26...Gas suction piping, 27...
…Constant pressure expansion valve.

Claims (1)

[Claims] 1. A condenser 3, an expansion mechanism 5, an evaporator 7, and a compressor 1 are connected in order through refrigerant piping, and a four-way valve 2 is provided, and the four-way valve 2 connects to a compressor discharge pipe 9. A normal inlet 19 is connected to the refrigerant pipe between the evaporator 7 and the compressor 1, a normal outlet 21 is connected to the refrigerant pipe between the expansion mechanism 5 and the evaporator 7 from the pipe side to the four-way valve 2 side. One inlet/outlet 22 is connected to the condenser inlet pipe 3a through a check valve 23 that prevents the flow of refrigerant to the other inlet/outlet 20.
A defrosting device for a refrigerator, characterized in that the defrosting device is configured to communicate with each other. 2. The condenser fan 17 is provided in the condenser 3, and a constant pressure expansion valve 27 is interposed between the evaporator 7 and the compressor 1 and the regular outlet 21 of the four-way valve 2, and a defrost fan 17 is provided in the condenser 3. Sometimes the condenser fan 17
A defrosting device for a refrigerator according to claim 1, characterized in that the defrosting device operates a refrigerator.