JPH0120709B2 - - 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. In particular, it relates to defrosting by switching from a heating cycle to a cooling cycle.

<Prior art> 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. 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. During heating operation, the high temperature and 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, high temperature and high pressure refrigerant gas is passed to the outdoor heat exchanger 4 by switching the four-way switching valve 3 from the heating cycle to the cooling cycle. , the frost adhering to the heat exchanger 4 is exchanged with the frost to melt and remove the frost, but when the four-way switching valve 3 is switched, the high pressure liquid refrigerant in the indoor heat exchanger 6 is removed. The refrigerant flows back into the compressor 1 and accumulates in the accumulator 2, which prevents liquid compression, resulting in an insufficient amount of refrigerant circulating during the refrigeration cycle, making it impossible to perform sufficient defrosting. This has the disadvantage that it requires a large amount of time, and heating operation cannot be performed during that time, leading to a drop in room temperature and impairing comfort.

<Problem to be Solved by the Invention> It is to prevent liquid refrigerant on the high pressure side from flowing back into the compressor when switching from heating operation to defrosting operation.

<Means for solving the problem> Compressor 11, outdoor heat exchanger 13, pressure reducing device 1
5. The indoor heat exchangers 16 are connected in sequence, and the first solenoid valve 12 is interposed between the discharge side of the compressor 11 and the outdoor heat exchanger 13, and the indoor heat exchanger 16 and A second solenoid valve 17 is interposed between the suction side of the compressor 11 and the second solenoid valve 17 is interposed between the discharge side of the compressor 11 and the
A first bypass passage 20 is provided that communicates with the inlet side of the solenoid valve 17, and a second bypass passage 21 is provided that communicates the outlet side of the first solenoid valve 12 with the suction side of the compressor 11. 1 bypass flow path 2
A heat pump type refrigeration cycle is constructed by interposing a third solenoid valve 19 in the second bypass passage 21 and a fourth solenoid valve 22 in the second bypass passage 21.

In such a cycle, during heating, the refrigerant discharged from the compressor 11 is passed through the first bypass passage 20 by closing the first solenoid valve 12 and opening the third solenoid valve 19. , to the indoor heat exchanger 16. Then, by opening the fourth electromagnetic valve 22, the refrigerant that has passed through the indoor heat exchanger 16 and passed through the pressure reducing device and the outdoor heat exchanger 13 is passed through the second bypass flow path 21. It is returned to the suction side of the compressor 11.

On the other hand, during defrosting, the fourth solenoid valve 22 is closed and the first solenoid valve 12 is opened to allow high pressure refrigerant to flow into the low pressure side, and then the third solenoid valve 1
9 and open the second solenoid valve 17, the refrigerant discharged from the compressor 11 is transferred to the outdoor heat exchanger 1.
3. Flow through the pressure reduction device and the indoor heat exchanger in sequence.

<Function> When switching from heating operation to defrosting operation, the fourth
By closing the first solenoid valve 22 and opening the first solenoid valve 12, the high-pressure refrigerant passes through the first bypass flow path 20 without passing through the compressor 11, and is transferred to the outdoor side heat exchanger on the low pressure side. Flow into the vessel. As a result, the high-pressure refrigerant does not remain in the compressor 11 or the accumulator, and moreover, defrosting is partially performed by flowing the high-pressure refrigerant into the outdoor heat exchanger. In this way, after the high and low pressures centered on the compressor 11 are balanced to some extent, the third solenoid valve 19 is closed and the second solenoid valve 17 is opened, resulting in a complete reverse cycle (cooling cycle). Do frost.

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

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 for compressing refrigerant gas, and a first solenoid valve 12 is installed on the discharge side of the compressor.
One end of the outdoor heat exchanger 13 is connected to the outdoor heat exchanger 13 via a fifth electromagnetic valve 14 that is closed when the compressor 11 stops operating, and an expansion device 15 to the other end of the outdoor heat exchanger 13. One end of the indoor heat exchanger 16 is connected, and the compressor 1 is connected to the other end of the indoor heat exchanger 16 via a second solenoid valve 17 and an accumulator 18.
The suction side of 1 is connected.

A first bypass flow path 20 is provided that communicates between the flow path between the compressor 11 and the first solenoid valve 12 and the flow path between the indoor heat exchanger 16 and the second solenoid valve 17. , a third solenoid valve 19 is interposed in the first bypass flow path 20, and a flow path between the first solenoid valve 12 and the outdoor heat exchanger 13 and the second
A second bypass flow path 21 is provided to communicate between the solenoid valve 17 and the flow path between the compressor 11, and a fourth solenoid valve 22 is interposed in the second bypass flow path 21.

3 and 4 show the compressor 11, the first solenoid valve 12, the second solenoid valve 17, and the third solenoid valve 1 in the heat pump refrigeration cycle of the present invention.
9. This shows the operating states of the fourth solenoid valve 22 and the fifth solenoid valve 14 during cooling operation and heating operation, and when the compressor 11 is started or stopped, each solenoid valve is It operates as shown in Figure 4.

First, during cooling operation, when the first solenoid valve 12, second solenoid valve 17, and fifth solenoid valve 14 are opened and the compressor 11 is operated, the high temperature and high pressure refrigerant gas compressed by the compressor 11 is released. is the first solenoid valve 12
The flow passes through the outdoor heat exchanger 13 and is condensed there, followed by the fifth solenoid valve 14 and the expansion device 15.
It is sent into the indoor heat exchanger 16 via. The liquid refrigerant sent to the indoor heat exchanger 16 evaporates within the indoor heat exchanger 16, and at this time takes vaporization heat from the surroundings. After that, the refrigerant gas vaporized in the indoor heat exchanger 16 is returned to the compressor 11 through the second electromagnetic valve 17. By repeating this operation, the interior of the room is cooled to a predetermined temperature by the indoor heat exchanger 16.

When the indoor temperature reaches a predetermined temperature, a thermostat (not shown) operates to stop the operation of the compressor 11, and the first solenoid valve 12 and the fifth solenoid valve
The third solenoid valve 14 is closed, and the third solenoid valve 19 is opened. Therefore, the refrigerant on the high pressure side of the compressor 11 flows to the low pressure side of the compressor 11 through the first bypass passage 20, and the pressures on the discharge side and suction side of the compressor 11 are balanced. Also, at this time, the first solenoid valve 1
outdoor heat exchanger 13 between the second and fifth solenoid valves 14
The high-pressure refrigerant inside is maintained at a state close to that of normal operation.

After that, the room temperature rises, and when the thermostat detects this, the compressor 11 is restarted and the first
The solenoid valve 12 and the fifth solenoid valve 14 are opened,
Also, the third solenoid valve 19 is closed. In this way, normal operation is immediately started.

Next, heating operation will be explained. During heating operation, the third solenoid valve 19 and the fourth solenoid valve 22 are opened, and the first solenoid valve 12 and the second solenoid valve 17 are opened.
The compressor 11 only needs to be operated by closing the compressor 11, and by doing so, the refrigerant gas from the compressor 11 passes through the third electromagnetic valve 19 and the first bypass passage 20 to the indoor heat exchanger. 16 , where it is condensed and then fed to the outdoor heat exchanger 13 through the expansion device 15 and the fifth solenoid valve 14 . That is, the indoor heat exchanger 16 acts as a condenser, and the outdoor heat exchanger 13 acts as an evaporator. The refrigerant gas evaporated in the outdoor heat exchanger 13 is returned to the compressor 11 through the second bypass passage 21 and the fourth electromagnetic valve 22.

After that, when the indoor temperature reaches a predetermined temperature due to the action of the indoor heat exchanger 16, the thermostat operates to stop the operation of the compressor 11, and the third solenoid valve 19 and the fifth solenoid valve 14 are activated. is closed and the first solenoid valve 12 is opened. In this way, the high pressure refrigerant gas in the compressor 11 flows to the low pressure side via the first electromagnetic valve 12 and the second bypass flow path 21, and the pressure is balanced, and the indoor heat is The high pressure refrigerant in the exchanger 16 is retained.

When restarting, compressor 1 operates in the same way as during cooling.
1 starts, the third solenoid valve 19 and the fifth solenoid valve
The first solenoid valve 14 is opened, and the first solenoid valve 12 is closed. In this way, normal heating operation begins.

Next, the defrosting operation will be explained. FIG. 5 shows the compressor 11, the first solenoid valve 12, the second solenoid valve 17, the third solenoid valve 19, the fourth solenoid valve 22, and the fifth solenoid valve 14 in the heat pump type refrigeration cycle. Fig. 5 shows the operating state when switching the refrigeration cycle, and each electromagnetic valve operates as shown in Fig. 5 when switching the refrigeration cycle during defrosting. That is, when performing a defrosting operation to remove frost attached to the outdoor heat exchanger 13 during heating operation, the refrigeration cycle is switched from heating operation to cooling operation. After closing 22, the first
The solenoid valve 12 is opened.

By doing this, the high temperature, high pressure refrigerant accumulated in the indoor heat exchanger 16 is transferred to a low temperature state through the first bypass passage 20, the third solenoid valve 19, and the first solenoid valve 12. , low pressure outdoor heat exchanger 1
It flows into 3. At this time, the fourth electromagnetic valve 22 is closed, so that high-temperature, high-pressure refrigerant liquid does not return to the suction side of the compressor 11 through the second bypass passage 21. At this time, the high temperature and high pressure refrigerant that has flowed into the indoor heat exchanger 13 and the outdoor heat exchanger 13
The frost that adheres to the surface exchanges heat with the frost, and the frost begins to melt. Next, the indoor heat exchanger 16 and the outdoor heat exchanger 1
3 and the pressure balance and the refrigerant no longer flows from the indoor heat exchanger 16 to the outdoor heat exchanger 13, the third solenoid valve 19 is closed, and then the second solenoid valve 17 is opened. do.

As a result, the refrigeration cycle is completely switched to cooling operation, and the refrigerant gas sucked into the compressor 11 from the indoor heat exchanger 16 side through the second solenoid valve 17 is transferred to the room through the first solenoid valve 12. The refrigerant gas is discharged to the outside heat exchanger 13, and frost adhering to the outdoor heat exchanger 13 is removed by this high-temperature, high-pressure refrigerant gas. By controlling each electromagnetic valve in this way, the refrigeration cycle can be switched without the refrigerant liquid flowing back to the suction side of the compressor 11, and the refrigerant liquid accumulates in the accumulator 12, causing the refrigerant in the cycle to Defrosting can be carried out efficiently because it prevents the amount from being insufficient.

Next, when switching the refrigeration cycle from defrosting operation (cooling operation) where defrosting is completed to heating operation, first close the second solenoid valve 17, then close the third solenoid valve 1.
Open 9. As a result, the outdoor heat exchanger 13
The high-pressure refrigerant liquid inside the first electromagnetic valve 12, the first
It flows into the indoor heat exchanger 16 through the bypass passage 20 and the third solenoid valve 19 . When the pressures of the outdoor heat exchanger 13 and the indoor heat exchanger 16 are balanced and the refrigerant no longer flows from the outdoor heat exchanger 13, the first solenoid valve 12 is closed, and then the fourth solenoid valve 12 is closed. Valve 22 is opened.

As a result, the refrigeration cycle is completely switched to the heating operation, and since the refrigerant liquid does not flow back to the suction side of the compressor 11 during this time, the heating operation can be immediately resumed in a state close to the normal state.

<Effects> According to the present invention, when switching from the heating cycle to the defrosting cycle, the high-pressure refrigerant is passed through the first bypass flow path to flow to the low-pressure outdoor heat exchanger without passing through the compressor. Since the high and low pressures are balanced before switching completely to the defrosting (cooling) cycle, high-pressure refrigerant does not flow into the compressor at the time of switching, and refrigerant does not accumulate in the compressor or accumulator.

Therefore, before completely switching to the defrosting cycle, high-temperature, high-pressure refrigerant flows into the outdoor heat exchanger to partially defrost the air, and after completely switching to the defrosting cycle, sufficient refrigerant circulates through the cycle. , defrosting can be performed efficiently and quickly in a short time, and the drop in indoor temperature during defrosting can be kept small to maintain comfort. In addition, since the cycle is switched once the high and low pressures are balanced and then completely switched, the defrosting operation and the heating operation can be started quickly, and the room temperature can be recovered quickly especially when the heating operation is restarted.

[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. FIG. 4 is an explanatory diagram of the operation of the solenoid valve during cooling, FIG. 4 is an explanatory diagram of the operation during heating, and FIG. 5 is an explanatory diagram of the operation during defrosting. 11 is a compressor, 12 is a first solenoid valve, 14 is a fifth solenoid valve, 17 is a second solenoid valve, 20 is a first bypass passage, 19 is a third solenoid valve, 21 is a second solenoid valve.
22 represents a fourth solenoid valve.

Claims (1)

[Claims] 1. A compressor 11, an outdoor heat exchanger 13, a pressure reducing device 15, and an indoor heat exchanger 16 are connected in sequence, and between the discharge side of the compressor 11 and the outdoor heat exchanger 13. A first solenoid valve 12 is interposed between the indoor heat exchanger 16 and the suction side of the compressor 11, and a second solenoid valve 17 is interposed between the indoor heat exchanger 16 and the suction side of the compressor 11. A first bypass passage 20 is provided that communicates with the inlet side of the solenoid valve 17, and a second bypass passage 21 is provided that communicates the outlet side of the first solenoid valve 12 with the suction side of the compressor 11. In a heat pump type refrigeration cycle in which a third solenoid valve 19 is interposed in the first bypass flow path 20 and a fourth solenoid valve 22 is interposed in the second bypass flow path 21, during heating, The refrigerant discharged from the compressor 11 is transferred to the first bypass passage 20 by closing the first solenoid valve 12 and opening the third solenoid valve 19.
The refrigerant that has passed through the indoor heat exchanger 16 and passed through the pressure reducing device and the outdoor heat exchanger 13 is passed through the fourth electromagnetic valve 2.
By opening 2, the air is returned to the suction side of the compressor 11 through the second bypass flow path 21. During defrosting, the fourth solenoid valve 22 is closed and the first solenoid valve 12 is closed. By opening the valve, the high-pressure refrigerant flows into the low-pressure side, and then by closing the third solenoid valve 19 and opening the second solenoid valve 17,
A defrosting control method for a heat pump refrigeration cycle, characterized in that refrigerant discharged from a compressor 11 is passed through an outdoor heat exchanger 13, a pressure reducing device, and an indoor heat exchanger in sequence.