JP2931326B2 - Refrigeration equipment - Google Patents

Description

The present invention relates to a defrosting operation of a refrigeration system.

(B) Conventional technology Japanese Patent Application No. 63-235812 discloses a refrigerating device to be incorporated in a showcase or a prefabricated refrigerator.

The refrigerating cycle is formed by connecting a compressor, a condenser, a liquid receiver, a decompressor, and an evaporator sequentially with a refrigerant pipe, and condensing the refrigerant discharged from the compressor during the defrosting operation of the evaporator. The refrigerant is directly guided to the evaporator by bypassing the vessel, the liquid receiver, and the pressure reducer, and the refrigerant from the evaporator is guided to the liquid receiver via the condenser. Then, the gas refrigerant in the liquid receiver is returned to the compressor.

As described above, during the defrosting operation, the refrigerant that has melted the frost of the evaporator is led to the receiver via the condenser,
This refrigerant is heated by the condenser and keeps the temperature of the refrigerant high, so that the defrosting time can be shortened.

(C) Problems to be Solved by the Invention However, when the outdoor temperature at which the condenser is placed (hereinafter referred to as “outside air temperature”) is low, the refrigerant is cooled by introducing the refrigerant to the condenser. And the defrosting time may be prolonged.

An object of the present invention is to shorten the defrosting time when the outside air temperature is low as much as possible.

(D) Means for Solving the Problems In order to achieve this object, the present invention provides a low-temperature pipe for bypassing a condenser and flowing a refrigerant to a receiver when the outside air temperature is low; In this case, a high-temperature pipe for flowing a refrigerant to a liquid receiver through a condenser is provided.

(E) Operation When the outside air temperature is high, the refrigerant in which the frost of the evaporator is melted flows to the receiver via the condenser, and the refrigerant is heated by the condenser. On the other hand, when the outside air temperature is low, this refrigerant is used Is bypassed to the condenser and flows to the receiver so that the refrigerant does not exchange heat with the condenser.

(F) Embodiment In FIG. 1, 1 is a compressor, 2 is a first three-way valve,
The one outlet side is connected to the condenser 3 and the other outlet end is connected to a first defrosting refrigerant pipe 5 which bypasses the condenser 3 and the liquid receiver 4. During the cooling operation and the first defrosting operation, the refrigerant is switched so as to flow in the direction indicated by the solid arrow a, and during the second defrosting operation and the pump-down operation, the refrigerant is switched so as to flow in the direction indicated by the solid arrow b. Reference numeral 6 denotes a liquid pipe connected to the lower part of the receiver 4, and the evaporator 9 is connected via a check valve 7 and a parallel circuit 8.
Connected to. The parallel circuit includes a decompressor 10 and a first on-off valve 11 connected in series, and a second on-off valve 12 connected in parallel to both of them.
The on-off valve 11 is opened during the cooling operation, and closed during the first and second defrosting operations and the pump-down operation. The second on-off valve 12 is closed during the cooling and pump-down operations, and is opened during the first and second defrosting operations. 13 is a low pressure tube, the third
One end is connected to the accumulator via the on-off valve 14 and the pressure regulating valve 15.
The other end is connected to an outlet pipe 17 of the evaporator 9. The third on-off valve 14 is opened during the cooling and pump down operations. Reference numeral 18 denotes a check valve provided in parallel with the third on-off valve 14. Reference numeral 19 denotes a second refrigerant pipe for defrosting, one end of which is connected to the outlet pipe 17 of the evaporator 9. The other end is branched, and the other 20 (hereinafter referred to as a “low temperature pipe”) is a fourth pipe.
A pipe 22 connecting the receiver 4 and the condenser 3 via an on-off valve 21
And the other 23 (hereinafter referred to as "high temperature pipe") is a check valve
Each is connected to a pipe 25 connecting the three-way valve 2 and the condenser 3 via 24. The fourth on-off valve 21 is opened only when the outside air temperature during the first and second defrosting operations is low. 26 is the third
One end is connected to the upper part of the liquid receiver 4 and the other end is connected to the low-pressure pipe 13. A fifth opening / closing valve 27 is arranged in the refrigerant line 26. And this fifth on-off valve
27 is closed during the cooling operation and the pump down operation.
Also, it is opened during the second defrosting operation.

The operation states of the three-way valve 2 and the respective on-off valves described above are collectively shown in the figure below.

During the cooling operation, the refrigerant discharged from the compressor 1 flows as indicated by a solid arrow. When frost is generated in the evaporator 9 by this cooling operation, first, a first defrosting operation is performed.

During the first defrosting operation, the refrigerant is caused to flow as indicated by a one-dot chain line arrow. That is, the gas refrigerant discharged from the compressor 1 flows to the condenser 3 and the liquid receiver, and sends the liquid refrigerant 28 in the liquid receiver 4 to the evaporator 9 via the liquid pipe 6 and the second on-off valve 12. . In this case, the refrigerant stops in the evaporator 9 by closing the third on-off valve 14 and the fourth on-off valve 21 and begins to melt frost by the heat of the refrigerant flowing into the evaporator 9. On the other hand, the gas refrigerant 29 in the liquid receiver 4 is returned to the compressor 1 by the refrigerant pipe 26 via the fifth on-off valve 27 and the pressure regulating valve 15. The reason why the pressure adjusting valve 15 is provided is to prevent the pressure of the gas refrigerant in the liquid receiver 4 from being directly applied to the compressor 1. Is smaller than the set value, the refrigerant is allowed to flow to the compressor 1. Then, when the pressure of the refrigerant in the receiver 4 becomes equal to or lower than the set value, the refrigerant returns to the compressor 1 as it is. As described above, during the first defrosting operation, the liquid refrigerant is sealed in the evaporator 9 so as to increase the temperature in the evaporator 9,
The frost attached to the evaporator 9 starts to be melted quickly.

This first defrosting operation is for temporarily filling the evaporator 9 with the refrigerant. Therefore, this operation time is about 30 seconds ~
It is one minute, and then the mode is switched to the second defrosting operation. Here, when the outside air temperature is low, the fourth on-off valve 21 is opened and a part of the refrigerant flowing out of the condenser 3 flows into the second defrosting pipe 19, but the second defrosting pipe 19 The flow is stopped by a check valve 30 in line 19.

During the second defrosting operation, the refrigerant flows as indicated by a two-dot chain line arrow. That is, the refrigerant discharged from the compressor 1 is guided to the evaporator 9 via the three-way valve 2, the first defrost line 5, and the second on-off valve 12. Then, the frost that has begun to melt in the evaporator 9 is reliably melted. Most of the refrigerant in the evaporator 9 is liquefied by melting the frost. Here, when the outside air temperature is relatively high, the refrigerant that has flowed out of the evaporator 9 by closing the fourth on-off valve 21 flows into the condenser 3 through the second defrost line 19, particularly the high-temperature tube 23, Here, it is heated and sent to the liquid receiver 4. Then, the pressure of the refrigerant flowing out of the liquid receiver 4 is adjusted by the pressure adjusting valve 15, and the refrigerant is returned to the compressor 1.
On the other hand, when the outside air temperature is low, the fourth on-off valve 21 is opened, so that the refrigerant discharged from the evaporator 9 is supplied to the second defrost pipe 19.
In particular, it is sent to the receiver via the low temperature pipe 20. That is, the refrigerant is prevented from flowing to the condenser 3 cooled by the outside air, thereby preventing the refrigerant from being cooled in the condenser 3. Thereby, the decrease in the temperature of the refrigerant is suppressed to a small value.

As described above, during the second defrosting operation, the refrigerant liquefied by the evaporator 9 is stored in the receiver 4. Then, when the temperature of the outlet pipe of the evaporator 9 becomes equal to or higher than a certain value, the second defrosting operation is terminated.

Thereafter, a pump-down operation is performed, and the evaporator 9 is operated.
Eliminate refrigerant inside. During this operation, all but the third on-off valve 14 is closed (only the third on-off valve 14 is open), and the refrigerant in the evaporator 9 is passed through the low-pressure pipe 13 to the accumulator 16, the condenser 3,
The liquid is collected in the liquid receiver 4 (see a broken arrow). At this time, since the refrigerant liquefied in the evaporator 9 by the second defrosting operation is stored in the receiver 4 in advance, the amount of the refrigerant remaining in the evaporator 9 is small. Can be shorter.

In the above embodiment, a sixth on-off valve (not shown) is provided in place of the check valve 24 in the high-temperature pipe 23, and this on-off valve is used during the first and second defrosting operations when the outside air temperature is low. The valve 21 may be closed and the on-off valve 21 may be opened when the outside air temperature is high.

Further, as shown in FIG.
To the low-temperature pipe 20 (in the direction of the solid arrow b) when the outside air temperature is low, and to the high-temperature pipe 23 when the outside air temperature is high by switching the three-way valve 31. Refrigerant may be allowed to flow (in the direction of the solid arrow a).

(G) Effect of the present invention As described above, in the present invention, when the outside air temperature is high, the refrigerant in which the frost of the evaporator is melted flows to the receiver through the condenser, and the refrigerant is heated by the condenser. On the other hand, when the outside air temperature is low, this refrigerant bypasses the condenser and flows to the receiver, so that the refrigerant is not exchanged with the condenser, so that even if the outside air temperature decreases, the defrosting time becomes longer. Can be suppressed. That is, the defrosting time can always be kept substantially constant without being affected by the change in the outside air temperature.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus showing one embodiment of the present invention, and FIG. 2 is a main part refrigerant circuit diagram of a refrigeration apparatus showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Compressor, 3 ... Condenser, 4 ... Receiver, 9 ... Evaporator, 10 ... Reducer, 19 ... Refrigerant pipe, 20 ... Low temperature pipe, 23 ... High temperature tube.

Claims (1)

(57) [Claims] 1. A refrigerating cycle is formed by connecting a compressor, a condenser, a liquid receiver, a decompressor, and an evaporator in order by a refrigerant pipe, and the high-temperature refrigerant of the refrigerating cycle is discharged during the defrosting operation of the evaporator. In the refrigerating device that flows the refrigerant to the evaporator and then guides the refrigerant to the receiver, and guides the gas refrigerant guided to the receiver to the compressor, a refrigerant line that guides the evaporator to the receiver is provided. When the outside air temperature is high, the high temperature pipe through which the refrigerant flows to the liquid receiver through the condenser, and when the outside air temperature is low, the low temperature pipe which bypasses the condenser, Refrigeration equipment.