JPH05296579A - Refrigerator - Google Patents

Abstract

PURPOSE:To prevent fusing of a fusible cock, a wet vapor suction and to hence stably defrost by introducing discharge gas to an evaporator via a bypass circuit without introducing a liquid reservoir when a temperature near the cock becomes a specified temperature or higher. CONSTITUTION:Discharge gas of a compressor 1 is introduced to a liquid reservoir 3 by bypassing a condenser 2. The discharge gas and liquid refrigerant from the reservoir 3 are simultaneously bypassed through an expansion valve 4, and introduced into an evaporator 5 to be defrosted. In such a hot gas defrosting type refrigerator, in order to prevent fusing of a fusible cock 11 provided in the reservoir 3 or a liquid tube, a bypass circuit 16 for introducing the discharge gas directly into the evaporator 5 without introducing to the reservoir 3 if a temperature near the cock 11 becomes a specified temperature or higher during defrosting is provided. That is, a solenoid valve 8 is closed by an operation of a temperature sensor 19, a solenoid valve 9 is opened to introduce the discharge gas from the circuit 16 to the evaporator 5.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a refrigeration system cycle incorporating a hot gas defrost system.

[0002]

2. Description of the Related Art A conventional refrigerating apparatus has a structure as disclosed in Japanese Patent Laid-Open No. 63-73071, in which a discharge gas is introduced into a receiver and sent simultaneously with a refrigerant liquid to an evaporator, and if necessary. It does not have a structure in which only the gas is sent by switching the bypass circuit.

[0003]

In the above prior art, when the amount of refrigerant retained in the receiver during defrosting is small, it is possible to raise the temperature in the receiver by introducing the discharge gas in a very short time. There is a problem that the defrosting efficiency is reduced because the defrosting is temporarily interrupted by the operation of the melt stopper protection thermostat or the like. Also, if the amount of refrigerant retained in the receiver is too large, a large amount of liquid refrigerant will be introduced into the evaporator, causing liquid back to the compressor during defrosting operation or during cooling operation immediately after defrosting. It was easy.

An object of the present invention is to perform a stable defrosting operation in a hot gas defrosting system which uses a condensed liquid refrigerant and a discharge gas at the same time during defrosting, without being largely influenced by the amount of refrigerant in the receiver. is there.

[0005]

[Means for Solving the Problems] The above object is to receive the discharged gas introduced by bypassing the receiver during defrosting when the temperature near the fusible plug rises or when the compressor suction pipe section falls. This is achieved by stopping the introduction into the evaporator and introducing the discharge gas directly into the evaporator through a bypass pipe connecting the discharge pipe and the evaporator inlet.

[0006]

[Operation] The compressor discharge pipe has a bypass pipe bypassing the condenser and connected to the receiver inlet, and a bypass pipe bypassing the condenser and receiver to the evaporator inlet. The solenoid valve is connected to the. At the start of defrosting, the compressor discharge gas bypasses the condenser and is introduced to the receiver inlet, and the liquid refrigerant in the receiver is pushed out at the same time as the discharge gas and introduced into the evaporator. If the amount of liquid refrigerant inside is small, the temperature of the receiver and the liquid pipe will rise due to the heat effect of the discharged gas.If the amount of liquid refrigerant is too large, a large amount of liquid refrigerant will be introduced into the evaporator and will be in a liquid back state and sucked. The gas temperature drops significantly.

When each of these temperatures reaches the standard value, the bypass circuit is switched by the operation of the temperature detector to stop the introduction of the discharge gas into the liquid receiver and directly introduce it into the evaporator to stop the defrosting operation. Without this, it is possible to prevent melting of the fusible plug when the liquid cooling holding amount in the liquid receiver is small, and to prevent liquid back operation due to excessive liquid introduction into the evaporator when the liquid cooling holding amount is large.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a system diagram of a refrigerating apparatus according to an embodiment of the present invention.

In FIG. 1, a compressor 1, a condenser 2, a liquid receiver 3, an expansion valve 4, an evaporator 5, and an accumulator 6 constitute a basic refrigeration cycle, and a liquid is discharged from a discharge pipe 14 as a hot gas defrosting circuit. A bypass pipe 15 connected to the inlet side of the container 3 via a solenoid valve 8 on the way and a discharge pipe 14
Further, a bypass pipe 16 connected to the inlet side of the evaporator 5 via a solenoid valve 9 is incorporated in the middle thereof.

During a normal cooling operation in this cycle, the high-temperature high-pressure gas discharged from the compressor 1 enters the condenser 2 and is liquefied by opening the solenoid valve 7 provided on the discharge pipe 14 on the way. The liquefied refrigerant is decompressed by the expansion valve 4 through the liquid receiver 3, vaporized by the evaporator 5, and sucked into the compressor 1 through the accumulator 6 and the suction pressure adjusting valve 18.

Next, when the defrosting operation is started, the solenoid valve 7 is closed,
By opening the solenoid valve 8 provided in the middle of the bypass pipe 15, the high-temperature and high-pressure gas discharged from the compressor 1 bypasses the condenser 2 and enters the receiver 3 to be retained in the receiver. Mixes with the existing liquid refrigerant and exits the receiver. At this time, the solenoid valve 10 provided in the middle of the bypass pipe 21 connected in parallel with the expansion valve 4 opens simultaneously with the solenoid valve 8, so that the receiver 2
The liquid refrigerant mixed with the discharge gas discharged from the bypass bypasses the expansion valve 4 and is introduced into the evaporator 5. The discharge gas is condensed and liquefied into the accumulator 6 while frost is melted by the heat amount of the discharge gas and liquid. The gas portion is decompressed by the suction pressure adjusting valve 18 and sucked into the compressor 1. Also, check valve 1
2 and 13 are provided to regulate the flow direction of the refrigerant. During this defrosting operation, the liquid refrigerant in the liquid receiver 3 is introduced into the evaporator 5 and decreases with time, but when the amount of refrigerant held in the liquid receiver 3 is small, it is received by the introduction of high-temperature discharge gas. The temperature inside the liquid container rises, and the fusible plug 11 attached to the liquid receiver 3 is melted. In the conventional technology, the defrosting is temporarily interrupted here by the temperature detector 19, but in the cycle of the present invention, the electromagnetic valve 8 is closed at the same time as the solenoid valve 8 is opened by the operation of the temperature detector 19, and the discharge gas is directly supplied from the bypass pipe 16. The temperature rise of the liquid receiver 3 is prevented by introducing it into the evaporator 5 and switching to defrosting by the amount of heat of the discharged gas.

Contrary to the above, when the amount of refrigerant held in the receiver 3 is too large, a large amount of liquid refrigerant is sent to the evaporator 5 during defrosting, which causes liquid back operation during defrosting. It will be easier. Therefore, in the liquid back operation state, the compressor suction gas pipe 17
If the temperature falls below the specified level, the temperature sensor 20 attached to the suction pipe 17 operates to perform the same electromagnetic valve operation as described above, thereby allowing the discharge gas to bypass the liquid receiver 3 and directly to the evaporator 5 It is possible to prevent the liquid back operation by introducing the liquid refrigerant into the evaporator 5 and stopping the supply of the liquid refrigerant in the liquid receiver 3 to the evaporator 5.

Although this embodiment has been described by taking the example of the simple hot gas system, the same structure and control can be used in the re-evaporation system having a plurality of evaporators.

[0015]

According to the present invention, the by-pass circuit of the discharge gas is switched according to the temperature state of the receiver and the temperature state of the intake gas during defrosting of the hot gas, so that the liquid refrigerant holding amount in the receiver is changed. Irrespective of, it is possible to prevent melting of the fusible plug, liquid back operation, etc., and there is no need to interrupt defrosting on the way, so stable defrosting is possible.

[Brief description of drawings]

FIG. 1 is a system diagram of a refrigerating apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Compressor, 2 ... Condenser, 3 ... Liquid receiver, 4 ... Expansion valve, 5
... Evaporator, 6 ... Accumulator, 8, 9, 10 ... Solenoid valve, 11 ... Soluble plug, 15, 16 ... Bypass piping, 19,
20 ... Temperature detector.

Claims (1)

[Claims] 1. A discharge gas from a compressor is introduced into a liquid receiver by bypassing a condenser, and the discharge gas and the liquid refrigerant in the liquid receiver are simultaneously introduced into an evaporator by bypassing an expansion valve. In a hot gas defrosting type refrigerating device that performs defrosting, the temperature near the fusible plug during defrosting is at or above a specified temperature during defrosting to prevent melting of the fusible plug provided in the receiver or liquid pipe. In this case, the refrigerating apparatus is provided with a bypass circuit for directly introducing the discharge gas to the evaporator without introducing the liquid receiver.