JPS6361584B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a defrosting control method for a heat pump type refrigeration cycle, and particularly to a method of switching from a heating cycle to a cooling cycle during defrosting.

<Prior art> In a conventional heat pump refrigeration cycle, a compressor 1, a four-way switching valve 3, an outdoor heat exchanger 4, an expansion device 5, and an indoor heat exchanger 6 are sequentially connected in an annular manner as shown in FIG. During cooling operation, high-temperature, high-pressure refrigerant gas from the compressor 1 is sent to the outdoor heat exchanger 4 as shown by the solid line arrow, where it is condensed and then evaporated in the indoor heat exchanger 6 via the expansion device 5 for heating. During operation, high-temperature, high-pressure refrigerant gas from the compressor 1 is reversely circulated as shown by the broken line arrow to perform heating.

Generally, in this type of refrigeration cycle, when defrosting is performed during heating operation, the four-way switching valve 3 is switched to flow high-temperature, high-pressure refrigerant gas to the outdoor heat exchanger 4. However, when the four-way switching valve 3 is switched, the high-pressure liquid refrigerant in the indoor heat exchanger 6 flows back into the compressor 1, causing the liquid to be compressed. The amount of refrigerant that accumulates in the preventive accumulator 2 and circulates through the refrigeration cycle is insufficient, so sufficient defrosting cannot be performed. The disadvantage is that it causes a drop in room temperature and impairs comfort.

<Problems to be Solved by the Present Invention> It is an object of the present invention to prevent high-pressure refrigerant from flowing back into the compressor and stagnation during defrosting switching, thereby enabling efficient defrosting.

<Means for solving the problem> A compressor, a four-way switching valve, an indoor heat exchanger, a pressure reducing device, and an outdoor heat exchanger are connected in sequence, and the cooling cycle and heating cycle are achieved by switching the passages with the four-way switching valve. A bypass flow path that communicates the low pressure side and the high pressure side formed by sandwiching the pressure reducing device is provided, and a first solenoid valve is interposed in the bypass flow path, and the four-way switching valve is connected to the four-way switching valve. A second solenoid valve is interposed between the and the compressor suction side, and when switching to defrosting operation, the first solenoid valve is opened and the second solenoid valve is closed, and then the first solenoid valve is closed. At the same time, the four-way valve is switched to the cooling cycle side, and then the second solenoid valve is opened.

<Operation> During defrosting, the first solenoid valve is first opened and the second solenoid valve is closed. As a result, the high-temperature refrigerant on the high-pressure side including the indoor heat exchanger flows into the outdoor heat exchanger through the bypass passage, and part of defrosting is performed.

Since the second solenoid valve is closed at this time, the refrigerant on the high pressure side is reliably prevented from flowing backward into the compressor.

In this way, when the high-pressure refrigerant flows into the outdoor heat exchanger and the high and low pressures across the pressure reducing device are balanced, the first solenoid is closed and the four-way switching valve switches from the heating cycle to the cooling (defrosting) cycle. It will be done. Finally, the second solenoid valve is opened to operate in a complete defrosting (cooling) cycle, and the high-temperature, high-pressure refrigerant from the compressor is sent to the outdoor heat exchanger to perform defrosting.

<Example> An example of the present invention will be described below based on the drawings.

Fig. 2 is a refrigerant circuit diagram of a heat pump type refrigeration cycle according to the present invention, Fig. 3 is an explanatory diagram of the operation of the four-way switching valve and the first and second solenoid valves in the refrigeration cycle, and Figs. FIG. 7 is a refrigerant circuit diagram showing another embodiment of the invention.

Note that solid arrows indicate the flow of refrigerant during cooling operation, and dashed arrows indicate the flow of refrigerant during heating operation.

In Figure 2, 11 is a compressor that compresses refrigerant gas, 12 is an accumulator for preventing liquid return, 13 is a four-way switching valve that switches between cooling operation and heating operation, and 14 is a condenser during cooling operation, and an evaporator during heating operation. outdoor heat exchanger acting as a container, 15
16 is an expansion device such as an expansion valve or a capillary reach tube; 16 is an indoor heat exchanger that acts as an evaporator during cooling operation and as a condenser during heating operation; 17
In this embodiment, the bypass flow path communicates the outdoor heat exchanger outlet with the indoor heat exchanger inlet, and the bypass flow path is shown in other embodiments in FIGS. 4 to 6. An arbitrary point in the flow path connecting the four-way switching valve 13 including the chamber 14 and the expansion device 15 is communicated with an arbitrary point in the flow path connecting the four-way switching valve 13 including the indoor heat exchanger 16 and the expansion device 15. It can be located anywhere as long as it is a bypass flow path. 18 is a first solenoid valve provided in the bypass flow path, and 19 is a second solenoid valve provided in a flow path connecting the suction side of the compressor 1 and the four-way switching valve 13.

FIG. 3 shows the operations of the four-way switching valve 13, the first solenoid valve 18, and the second solenoid valve 19.

The operation of the refrigeration cycle will be explained using FIG. 3.

In this refrigeration cycle, during normal heating operation, the first solenoid valve 18 is always closed and the second solenoid valve 19 is always open, which is exactly the same as the operating state of the conventional cycle shown in FIG.

Now, during heating operation, when switching the refrigeration cycle to start defrosting in response to a signal from a timer de-icer or a frost detection device (not shown), first open the first solenoid valve 18, and then open the second solenoid valve 18. Solenoid valve 1
Close 9. This may be done simultaneously or with a slight delay. By doing so, the high temperature and high pressure liquid refrigerant in the indoor heat exchanger 16 moves into the outdoor heat exchanger 14 without flowing back into the compressor 11. Due to the heat of the transferred high-temperature, high-pressure liquid refrigerant, a portion of the frost adhering to the outdoor heat exchanger 14 begins to melt.

In this way, the liquid refrigerant in the indoor heat exchanger 16
After moving into the outdoor heat exchanger 14, the first solenoid valve 18 is closed and the four-way switching valve 13 is switched. This may be done by detecting the pressure or temperature of the outdoor heat exchanger 14, or the first solenoid valve 18
It may be controlled temporally from the time of first opening.

After that, when the second solenoid valve 19 is opened, the main refrigeration cycle is completely switched to a reverse cycle, and the outdoor heat exchanger 14 is removed by the high-temperature, high-pressure refrigerant gas discharged from the compressor 11. Frost begins.

In this way, in this refrigeration cycle, when the refrigeration cycle is switched, the liquid refrigerant is held in the condenser without flowing back into the accumulator 12 of the compressor 11 and staying there, so efficient operation is possible immediately after the refrigeration cycle is switched. Therefore, effective defrosting is possible, liquid compression overcurrent due to liquid returning to the compressor 11, etc. can be prevented, and reliability can be improved.

Similarly, when switching to heating operation after defrosting, the first solenoid valve 18 is opened and the second solenoid valve 19 is opened.
After closing, the first electromagnetic valve 18 may be closed with a delay, the four-way switching valve 13 may be switched, and then the second electromagnetic valve 19 may be opened.

<Effects> According to the present invention, by first opening the first solenoid valve and closing the second solenoid valve when switching to defrost, the refrigerant on the high pressure side is passed through the bypass passage to the outdoor heat exchanger. By sending the refrigerant in, part of the defrosting can be performed, and by closing the second solenoid valve, it is possible to reliably prevent the high-pressure refrigerant from flowing back into the compressor.

When this condition is reached, the first solenoid valve is opened, the four-way switching valve is switched to the cooling (defrosting) cycle, and finally the second solenoid valve, which prevents refrigerant from flowing into the compressor, is opened. By completely switching to the defrost cycle to perform defrosting, it is possible to reliably eliminate refrigerant stagnation in the compressor and defrost efficiently, and also because some defrosting has already been performed. Combined with high efficiency, it is possible to defrost quickly.

[Brief explanation of drawings]

Fig. 1 is a refrigerant circuit diagram of a conventional heat pump refrigeration cycle, Fig. 2 is a refrigerant circuit diagram of a heat pump refrigeration cycle according to the present invention, and Fig. 3 shows a four-way switching valve, a first solenoid valve, and a 2 Operation explanatory diagrams of solenoid valves, Figures 4, 5, and 6
The figure is a refrigerant circuit diagram showing another embodiment according to the present invention. 11: Compressor, 12: Accumulator, 1
3: Four-way switching valve, 14: Outdoor heat exchanger, 15:
Expansion device, 16: indoor heat exchanger, 17: bypass passage, 18: first solenoid valve, 19: second solenoid valve.

Claims (1)

[Claims] 1. A cooling cycle is achieved by sequentially connecting a compressor, a four-way switching valve, an indoor heat exchanger, a pressure reducing device, and an outdoor heat exchanger, and switching passages with the four-way switching valve.
In the heating cycle forming device, a bypass flow path is provided that communicates the low pressure side and the high pressure side formed by sandwiching the pressure reducing device, and a first solenoid valve is interposed in the bypass flow path, and the four-way switching is performed. A second solenoid valve is provided between the valve and the compressor suction side, and when switching to defrosting operation, the first solenoid valve is opened and the second solenoid valve is closed, and then the first solenoid valve is closed. A defrosting control method for a heat pump type refrigeration cycle, in which a four-way valve is switched to the cooling cycle side at the same time, and a second solenoid valve is then opened.