JPS6255593B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a defrosting mechanism for a refrigeration system that uses a fluorocarbon refrigerant and is equipped with a temperature-type expansion valve that has a temperature-sensitive tube in the refrigeration cycle. The present invention relates to a method for shortening the defrosting time when the liquid refrigerant is configured to flow into the evaporator and to defrost by flowing into the liquid receiver and pressurizing the liquid refrigerant there.

[Conventional technology]

This type of refrigeration equipment is equipped with a temperature-type expansion valve having a temperature-sensing cylinder during the refrigeration cycle.The temperature-sensing cylinder detects the refrigerant gas temperature at the evaporator outlet, and if the temperature is high, the expansion valve is opened. When the temperature drops, the expansion valve closes and reduces the refrigerant flow rate to maintain a constant degree of superheat. In addition, if the defrosting mechanism simply circulates the hot gas from the compressor by directly flowing it into the evaporator during defrosting operation, it will take a long time to defrost when the amount of refrigerant is small and the outside temperature is low. It is conceivable that the liquid refrigerant also flows into the receiver and joins the evaporator through an expansion valve for the liquid refrigerant in the receiver to increase the amount of refrigerant and shorten the defrosting time. As a prior art, there is Japanese Patent Application Laid-Open No. 53-22644.

[Problems to be solved by the invention]

However, during the above-mentioned defrosting operation, the hot gas flowing into the evaporator is cooled by the heat of melting from the frost and becomes moist, so that the temperature-sensitive cylinder of the thermostatic expansion valve stops when the degree of superheat is zero and the refrigerant does not flow. When this occurs, the expansion valve closes, significantly restricting the flow of liquid refrigerant from the receiver. As a result, refrigerant is virtually no longer supplied from the receiver to the evaporator, leading to a shortage of refrigerant, and the defrosting time is approximately the same as when only hot gas from the compressor flows into the evaporator. becomes longer. The present invention was made in view of the above circumstances, and the hot gas from the compressor flows directly into the evaporator during defrosting operation, and at the same time flows into the liquid receiver and pressurizes the liquid refrigerant. When flowing into the evaporator through a temperature-type expansion valve with a temperature-sensitive cylinder, the temperature-sensing cylinder comes into contact with the hot gas pipe, detects the temperature of the hot gas, and opens the expansion valve, allowing the heated liquid refrigerant in the receiver to flow into the evaporator. It is an object of the present invention to provide a defrosting mechanism for a refrigeration system that allows refrigerant to quickly flow into an evaporator to reliably increase the amount of refrigerant and shorten defrosting time.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a compressor,
In a refrigeration system including a condenser, a liquid receiver, a temperature-type expansion valve having a temperature-sensitive tube, and an evaporator, a first defrosting circuit that guides hot gas discharged from a compressor during defrosting operation to a liquid receiver; A second defrosting circuit that leads directly to the evaporator is provided, and the opening degree of the expansion valve is increased depending on the temperature of the hot gas in the second defrosting circuit to cause the hot gas to flow into the evaporator from the second defrosting circuit. The refrigerant in the liquid receiver is forced to be sent to the evaporator via the expansion valve by the pressure of the hot gas in the first defrosting circuit.

【Example】

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, reference numeral 1 is a compressor, and the discharge side of the compressor 1 is connected to a condenser 3 through a discharge pipe 2. The condenser 3 is connected by a pipe 5 with a valve 4 to a closed liquid receiver 6 . A pipe 7 leading the liquid refrigerant from the liquid receiver 6 is connected to a temperature-type expansion valve 8, and the expansion valve 8 is connected to an evaporator 10 by a pipe 9, and the evaporator 10 is connected to the suction pipe 11 of the compressor 1. are connected to form a closed refrigeration cycle. Further, the temperature-sensitive tube 12 of the expansion valve 8 is attached in contact with the suction pipe 11 on the outlet side of the evaporator 10, and the capillary tube 13 from the temperature-sensing tube 12 and the external pressure equalization tube 14 from the suction tube 11 connect to the expansion valve 8. It is connected opposite to the operating section of No. 8. The temperature sensing cylinder 12 is usually filled with the same refrigerant, and is heated by the suction pipe 11 to generate a corresponding pressure to detect the gas temperature at the outlet of the evaporator 10. This pressure and the external pressure equalizing pipe 14
The amount of refrigerant is automatically adjusted to maintain a constant degree of superheating so that the refrigerating capacity of the evaporator 10 is maximized by balancing the pressure corresponding to the evaporation temperature derived by the evaporation temperature. In the defrosting mechanism according to the present invention in such a refrigeration system, a switching valve 15 is provided in the discharge pipe 2 from the compressor 1, and a defrosting hot gas pipe 16 is connected from the switching valve 15 to the evaporator 10. A pipe 17 connected to the inlet pipe 9 and branched from the pipe 16 is connected to the liquid receiver 6 via a check valve 18 so as to pressurize it. Then, the tube 16 further extends along the middle of the temperature sensing cylinder 1.
The expansion valve 8 is operated by heating the temperature sensing tube 12 with hot gas from the tube 16. Since the present invention is configured as described above, during normal refrigeration operation, the pipe 16 is shut off by the switching valve 15 and the valve 4 is opened, so that the high temperature and high pressure refrigerant gas from the compressor 1 is transferred to the condenser 3. The cooled and liquefied refrigerant is collected in the liquid receiver 6, and this liquid refrigerant is expanded by the expansion valve 8 and its pressure and temperature are lowered. This low-temperature, low-pressure refrigerant is then used in the evaporator 10.
The evaporated refrigerant gas is sucked into the compressor 1 again, and this operation is repeated thereafter. On the other hand, at this time, the gas temperature at the outlet of the evaporator 10 is detected by the temperature sensing tube 12, and this and the external pressure equalizing tube 1
4, the expansion valve 8 is opened when the temperature is high and the expansion valve 8 is closed when the temperature is low to adjust the amount of refrigerant. In this way, the degree of superheat is maintained constant, and the evaporator 10 Always get maximum refrigeration capacity. Then, during defrosting operation, the switching valve 15 is switched to the pipe 16, and the switching valve 4 is closed. Therefore, hot gas, which is a high temperature and high pressure refrigerant gas, from the compressor 1 flows into the evaporator 10 via a pipe 16 by a switching valve 15, and at the same time enters the liquid receiver 6 through a pipe 17, where it is prevented from leaking by a valve 4 and is heated. By applying pressure, the liquid refrigerant in the liquid receiver 6 is pushed out. By the way, the tube 16 is in contact with the temperature sensing tube 12 and warms the temperature sensing tube 12 with hot gas, so the suction tube 1
Even if the gas temperature at the outlet of the evaporator 10 of No. 1 is low, it is determined that the degree of superheat is too high and the expansion valve 8 is opened, and a large amount of liquid is released at once from the liquid receiver 6 pressurized with the hot gas. The refrigerant passes through the expansion valve 8 and enters the evaporator 1.
Flows into 0. In this way, the refrigerant that had been accumulated in the liquid receiver 6 from the initial stage of the defrosting operation joins together, becomes hot gas from the compressor 1, and circulates between the evaporator 10 and the evaporator 10 with this large amount of hot gas. Adhering frost is dissolved and removed in a short time. Note that when the refrigerating operation is returned to after the defrosting operation, the refrigerant gas no longer enters the pipe 16 due to switching of the switching valve 15, and as a result, the temperature sensing tube 12 automatically switches to the suction pipe 11, which has a higher temperature than the pipe 16. The temperature is detected and the expansion valve 8 is again controlled to open and close as described above. However, the present invention is not limited to the above-mentioned embodiment, but as shown in FIG. Two temperature sensing tubes 1
2' is provided, and both temperature sensing cylinders 12, 12' are connected to the switching valve 19.
It is connected to the capillary pipe 13 of the expansion valve 8 by.
During the defrosting operation, the switching valve 19 is switched to the temperature sensing cylinder 12', and the expansion valve 8 is opened and closed by the temperature sensing cylinder 12', thereby operating in exactly the same manner as in the above embodiment.

【Effect of the invention】

As described above, according to the present invention, in a refrigeration system equipped with a temperature-type expansion valve 8 having a temperature-sensitive tube 12,
During defrosting operation, even if the refrigerant becomes wet on the outlet side of the evaporator 10, the expansion valve 8
is opened and the refrigerant in the liquid receiver 6 is pushed out under pressure by hot gas and used for defrosting, so the amount of refrigerant is increased and the defrosting time can be shortened.
The opening operation of the expansion valve 8 is controlled by the temperature sensing tube 1 using hot gas.
Since this is done by heating 2, the structure is very simple. Furthermore, during freezing operation after defrosting operation, the temperature sensing cylinder 12 automatically closes the suction pipe 11.
Since refrigerant gas does not flow through the pipe 16 and there is no adverse effect, normal superheat degree control is performed.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing one embodiment of the defrosting mechanism according to the present invention, and FIG. 2 is a system diagram of main parts showing another embodiment. 1...Compressor, 3...Condenser, 6...Liquid receiver,
8... Expansion valve, 10... Evaporator, 12, 12'...
...Temperature cylinder, 16, 17...Hot gas tube.

Claims (1)

[Claims] 1 In a refrigeration system equipped with a compressor, a condenser, a liquid receiver, a temperature-type expansion valve having a temperature-sensitive tube, and an evaporator, a first filter is used to guide hot gas discharged from the compressor to the liquid receiver during defrosting operation. A frost circuit and a second defrost circuit that leads directly to the evaporator are provided, and the opening degree of the expansion valve is increased depending on the temperature of the hot gas in the second defrost circuit, and the hot gas is transferred from the second defrost circuit to the evaporator. 1. A defrosting mechanism for a refrigeration system, characterized in that the refrigerant in the receiver is forced to flow into the evaporator via an expansion valve by the pressure of the hot gas in the first defrosting circuit.