JPH0333990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat pump type refrigeration cycle.

In a conventional heat pump type 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. Sometimes, as shown by the solid arrow, high-temperature, high-pressure refrigerant gas from the compressor 1 is sent to the outdoor heat exchanger 4, where it is condensed and then evaporated in the indoor heat exchanger 6 via the expansion device 5, during heating operation. As shown by the broken line arrow, high-temperature, high-pressure refrigerant gas from the compressor 1 is reversely circulated 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. As the refrigerant accumulates in the preventive accumulator 2 and the amount of refrigerant circulating in the refrigeration cycle is insufficient, sufficient defrosting cannot be performed.
It takes a lot of time to defrost, and heating operation cannot be performed during that time, which causes a drop in room temperature and impairs comfort.

The present invention has been made with the aim of eliminating the above-mentioned drawbacks, and is a heat pump type refrigerator that prevents fluid from returning to the compressor during defrosting, performs effective defrosting, and shortens defrosting time. It provides a cycle.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 2 is a refrigerant circuit diagram of a heat pump type refrigeration cycle according to the present invention, and FIG. 3 is a refrigerant circuit diagram of a heat pump type refrigeration cycle showing another embodiment of the present invention.

Note that solid arrows indicate the flow of refrigerant during cooling operation, broken arrows indicate the flow of refrigerant during heating operation, and thin arrows indicate the flow of refrigerant during refrigeration cycle switching.

In FIG. 2, 11 is a compressor, 12 is an accumulator, 13 is a four-way switching valve that switches between cooling operation and heating operation, 14 is an outdoor heat exchanger that acts as a condenser during cooling operation and as an evaporator during heating operation, and 15 1 is an expansion device consisting of an expansion valve or a capillary reach tube, 16 is an evaporator during cooling operation, and an indoor heat exchanger which acts as a condenser during heating operation; 17 is an inlet side of compressor 11 and a four-way switching valve 13 A solenoid valve 18 is a first bypass that connects the flow path between the solenoid valve 17 and the four-way switching valve 13 and the flow path between the outdoor heat exchanger 14 and the four-way switching valve 13. A flow path 19 is a second bypass flow path connecting the flow path between the electromagnetic valve 17 and the four-way switching valve 13 and the flow path between the indoor heat exchanger 16 and the four-way switching valve 13, and 20 is the first bypass flow path. A first check valve 21 is provided in the bypass flow path, and 21 is a second check valve provided in the second bypass flow path.

Next, the operation of the refrigeration cycle of the present invention will be explained. In this refrigeration cycle, during normal operation, the solenoid valve 17 is open, and the first and second check valves 20,
21 is in a closed state, and the operating state is similar to that of the conventional refrigeration cycle shown in FIG.

During heating operation, the refrigeration cycle is switched from heating operation to cooling operation in order to start defrosting in response to a signal from a timer day icer or frost detection device (not shown). In this case, first, the solenoid valve 17 is closed, and then the four-way switching valve 13 is switched. Now, the high temperature and high pressure refrigerant that had accumulated in the indoor heat exchanger 16 is removed from the four-way switching valve 13 and the first
It flows into the low-temperature, low-pressure outdoor heat exchanger 14 through the bypass passage 18 and the first check valve 20 . At this time, since the solenoid valve 17 is closed, the compressor 1
It is possible to prevent liquid refrigerant from being sucked into the suction side of 1. The high-temperature, high-pressure refrigerant that has flowed into the indoor heat exchanger 14 begins to melt the frost that has adhered to the outdoor heat exchanger 14 . Next, when the pressures of the indoor heat exchanger 16 and the outdoor heat exchanger 14 are balanced and the refrigerant no longer flows from the indoor heat exchanger 16 to the outdoor heat exchanger 14, the solenoid valve 17 is opened. At this time, the pressure in the outdoor heat exchanger 14 becomes higher than the pressure in the flow path between the four-way switching valve 13 and the solenoid valve 17 due to the gas discharged from the compressor 11, and the first check valve 20 is in the closed state. This results in an operating state similar to that of the conventional cycle shown in FIG.

In this way, the frost adhering to the outdoor heat exchanger 14 is melted and removed by the high-temperature, high-pressure discharge gas from the compressor 11.

When defrosting is completed and the heating operation is to be switched again, the solenoid valve 17 is first closed, and then the four-way switching valve 13 is switched. Now the outdoor heat exchanger 14
The high pressure refrigerant stagnant inside the four-way switching valve 1
3. Second bypass flow path 19, second check valve 21
and into the low pressure indoor heat exchanger 16. Since the solenoid valve 17 is closed at this time,
Liquid refrigerant can be prevented from being sucked into the suction side of the compressor 11.

Next, the outdoor heat exchanger 14 and the indoor heat exchanger 1
6 opens the solenoid valve 17 when the pressure is balanced and refrigerant no longer flows from the outdoor heat exchanger 14 to the indoor heat exchanger 16. At this time, the pressure in the indoor heat exchanger 16 becomes higher than the pressure in the flow path between the four-way switching valve 13 and the solenoid valve 17 due to the gas discharged from the compressor 11, and the second check valve 21 closes. The heating operation will resume.

FIG. 3 shows another embodiment of the present invention,
A first bypass flow path 18 is provided to connect the flow path between the solenoid valve 17 and the four-way switching valve 13 and the flow path between the outdoor heat exchanger 14 and the expansion device 15. A bypass flow path 19 is provided to connect the flow path between the solenoid valve 17 and the four-way switching valve 13 and the flow path between the indoor heat exchanger 16 and the expansion device 15. It performs the same control and operation as the embodiment shown in the figure.

In carrying out the present invention, the first bypass passage 18 is a passage between the electromagnetic valve 17 and the four-way switching valve 13 and the four-way switching valve 13 including the outdoor heat exchanger 14.
A bypass flow path connecting any point in the flow path between the expansion device 15 and the expansion device 15 may be used.
may be a bypass flow path connecting the flow path between the solenoid valve 17 and the four-way switching valve 13 and the flow path between the four-way switching valve 13 including the indoor heat exchanger 16 and the expansion device 15 at any point.

As described above, according to the present invention, when switching the refrigeration cycle for defrosting during heating operation, liquid refrigerant flows from the indoor heat exchanger or the outdoor heat exchanger into the suction side of the compressor, and the accumulator This prevents defrost from accumulating in the air, enabling efficient defrosting in a short time and reducing the drop in room temperature during defrosting.

Even after returning from defrosting operation to heating operation, operation can be performed immediately with a refrigerant distribution close to a steady state, so the room temperature can be recovered quickly and heating can be performed with excellent comfort.

Moreover, since the outdoor heat exchanger can always be used in an efficient state with little frost, efficient heating operation is possible.

Furthermore, since liquid can be prevented from returning to the compressor, the reliability of the compressor is also improved.

[Brief explanation of drawings]

Figure 1 is a refrigerant circuit diagram of a conventional heat pump type refrigeration cycle, Figure 2 is a refrigerant circuit diagram of a heat pump type refrigeration cycle according to the present invention, and Figure 3 is a refrigerant circuit diagram of a heat pump type refrigeration cycle showing another embodiment of the present invention. It is a refrigerant circuit diagram. 11 is a compressor, 12 is an accumulator, 13
is a four-way switching valve, 14 is an outdoor heat exchanger, 15 is an expansion device, 16 is an indoor heat exchanger, 17 is a solenoid valve,
18 is a first bypass flow path, 19 is a second bypass flow path, 20 is a first check valve, and 21 is a second check valve.

Claims (1)

[Claims] 1. A compressor, a four-way switching valve, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger are connected in sequence, and defrosting during heating is performed from the heating cycle to the cooling cycle using the four-way switching valve. In the heat pump type refrigeration cycle, which is performed by switching to the
A solenoid valve that opens and closes the flow path is provided, and a flow path between the solenoid valve and the four-way switching valve, and an arbitrary point between the four-way switching valve including the outdoor heat exchanger and the electric expansion valve; A first bypass passage is provided that connects the solenoid valve and the four-way switching valve, and a check valve is provided in the first bypass passage that allows flow only from the four-way switching valve side to the outdoor heat exchanger side. A second bypass passage is provided that connects the flow path between the two and an arbitrary point between the four-way switching valve including the indoor heat exchanger and the electric expansion valve, and a second bypass passage is provided in the second bypass passage. A check valve that allows flow only from the four-way switching valve side to the indoor heat exchanger side is provided, and a control unit that controls the operation of the refrigeration cycle and the four-way switching valve and the solenoid valve is provided, The control section includes a four-way switching valve control means that switches the four-way switching valve to the cooling cycle side during cooling operation or defrosting operation and switches the four-way switching valve to the heating cycle side during heating operation; a solenoid valve control means for controlling the flow path to open at the time of defrosting and closing the flow path at the time of switching to start defrosting; A defrosting start control means controls to open a solenoid valve with a delay after switching to a defrosting cycle, and a four-way switching valve is controlled to switch from a cooling cycle to a heating cycle after closing the solenoid valve when switching to end defrosting. A heat pump type refrigeration cycle comprising: a defrosting end control means for controlling a solenoid valve to open with a delay after switching;