JP4471810B2 - Air conditioner - Google Patents

Description

  The present invention has an outdoor unit and a plurality of indoor units, and allows the plurality of indoor units to perform cooling operation or heating operation at the same time, or to perform a mixture of these heating operation and cooling operation. Relates to the device.

In general, there is known an air conditioner in which a plurality of indoor units can be simultaneously operated for cooling or heating, or these heating and cooling operations can be performed in combination (see Patent Document 1). In this type of air conditioner, an outdoor unit including a compressor and an outdoor heat exchanger and a plurality of indoor units including an indoor heat exchanger and an indoor expansion valve are connected to each other through an inter-unit pipe. And, one end of the outdoor heat exchanger is alternatively branched and connected to the refrigerant discharge pipe and the refrigerant suction pipe of the compressor, and the inter-unit pipe is a high-pressure gas pipe connected to the refrigerant discharge pipe, A low pressure gas pipe connected to the refrigerant suction pipe and a liquid pipe connected to the other end of the outdoor heat exchanger are configured. One end of the indoor heat exchanger is connected to the high-pressure gas pipe and the low-pressure gas pipe via the high-pressure gas branch pipe and the low-pressure gas branch pipe, respectively, and the other end is connected to the liquid pipe via the liquid branch pipe. A first on-off valve and a second on-off valve are provided in the gas branch pipe and the low-pressure gas branch pipe, respectively.
In this type, when the heating operation of the indoor unit is stopped, the high-pressure gas refrigerant remains in the indoor heat exchanger. When the operation mode is changed from this state, it is necessary to return the internal pressure of the indoor heat exchanger to a low pressure. For this reason, conventionally, a balance valve is provided in parallel with the second on-off valve of the low-pressure gas branch pipe, and by opening this balance valve, the high pressure and the low pressure are balanced, and the interior of the indoor heat exchanger is returned to a low pressure. .
Japanese Patent No. 2804527

  However, in the conventional system, when the heating operation of the indoor unit is stopped or changed to the cooling operation, the first on-off valve is closed and the balance valve is opened suddenly, so that the pressure between the high-pressure refrigerant and the low-pressure refrigerant is increased. In order to balance the above, there is a problem that the high-pressure gas refrigerant in the indoor heat exchanger flows into the low-pressure gas pipe all at once, so that refrigerant noise and vibration are generated when passing through the balance valve.

  An object of this invention is to provide the air conditioning apparatus which can suppress generation | occurrence | production of a refrigerant | coolant sound and a vibration, when stopping the heating operation of an indoor unit or changing to a cooling operation.

In order to achieve the above object, the present invention provides an outdoor unit including a compressor, an outdoor heat exchanger and an outdoor expansion valve, and a plurality of indoor units including an indoor heat exchanger and an indoor expansion valve. A high-pressure gas pipe connected to the refrigerant discharge pipe and a refrigerant suction pipe of the compressor, and one end of the outdoor heat exchanger is connected to the refrigerant discharge pipe. A low pressure gas pipe connected to the refrigerant suction pipe and a liquid pipe connected to the other end of the outdoor heat exchanger, and one end of the indoor heat exchanger is connected to the high pressure gas pipe and the low pressure gas pipe, Each is connected via a high-pressure gas branch pipe and a low-pressure gas branch pipe, the other end is connected to a liquid pipe via a liquid branch pipe, and an open / close valve is provided in each of the high-pressure gas branch pipe and the low-pressure gas branch pipe. A balance valve is provided in parallel with the open / close valve of the branch pipe. The indoor unit can be cooled or heated at the same time, or the cooling operation and the heating operation can be performed together, and the heating operation of any of the indoor units is stopped or the cooling operation is performed. When opening and closing, the on-off valve provided on the high-pressure gas branch pipe, the on-off valve and balance valve provided on the low-pressure gas branch pipe are closed , the indoor expansion valve is opened, and the indoor heat exchange is performed. The indoor fan is operated toward the chamber, this state is maintained for a predetermined time, and the indoor heat exchanger is filled with liquid refrigerant. Then, the indoor expansion valve is closed and the low-pressure gas branch pipe is provided. An operation change pre-processing means for opening the balance valve is provided.

  In this case, the predetermined time may be a time set in advance as a time sufficient for the liquid refrigerant in the liquid pipe to flow into the indoor heat exchanger.

  ADVANTAGE OF THE INVENTION According to this invention, when heating operation of an indoor unit is stopped or it changes into cooling operation, generation | occurrence | production of a refrigerant | coolant sound and a vibration can be suppressed.

<First Embodiment>
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a circuit diagram showing an embodiment of an air conditioner according to the present invention. The air conditioner 1 includes a plurality of (for example, two) outdoor units 2A and 2B and a plurality of (for example, two) indoor units 3A and 3B. The inter-unit piping 5 that connects the outdoor units 2A, 2B and the indoor units 3A, 3B includes a low-pressure gas pipe 6, a high-pressure gas pipe 7, and a liquid pipe 8. The air conditioner 1 includes the indoor unit 3A. 3B can be simultaneously operated for cooling or heating, or can be implemented by mixing these cooling and heating operations.

  The outdoor unit 2A includes a variable capacity compressor (DC inverter compressor) 20A, constant capacity compressors (AC compressors) 20B1 and 20B2, an outdoor heat exchanger 21, an outdoor expansion valve 22, and a receiver. It is generally composed of a tank 23 and the like. Hereinafter, the compressors 20 </ b> A, 20 </ b> B <b> 1, 20 </ b> B <b> 2 are referred to as the compressors 20 when it is not necessary to distinguish between them.

  In the outdoor unit 2A, the compressors 20A, 20B1, and 20B2 are connected in parallel, and the refrigerant suction pipe 30 that is commonly connected to the suction ports of the compressors 20A, 20B1, and 20B2 is connected to the low-pressure gas pipe 6 via the accumulator 24. Connected to. The refrigerant discharge pipe 31 connected to the discharge ports of the compressors 20A, 20B1, and 20B2 branches into two via the oil separator 25, and one refrigerant discharge branch pipe 31A is connected to the high-pressure gas pipe 7. The other refrigerant discharge branch pipe 31B is connected to the outdoor heat exchanger 21.

  Here, the refrigerant discharge branch pipe 31 </ b> B is provided with a switching valve 40, and when the switching valve 40 is opened, the refrigerant discharged from the compressor 20 is supplied to the outdoor heat exchanger 21. Further, the refrigerant discharge branch pipe 31B is provided with a four-way valve 41 between the switching valve 40 and the outdoor heat exchanger 21, and the four-way valve 41 is viewed from the outdoor heat exchanger 21 as an outdoor heat exchanger. Switching valve for selectively switching one end of the vessel 21 to one of the refrigerant discharge branch pipe 31B and the refrigerant discharge branch pipe 31A connected to the switching valve 40 or the heating path pipe 32 connected to the suction pipe 30 of the compressor 20 Function as.

  The other end of the outdoor heat exchanger 21 is connected to the liquid pipe 8 via an outdoor expansion valve 26 for adjusting the flow rate of refrigerant supplied to the outdoor heat exchanger 21, a receiver tank 23, and a trap pipe 27. The receiver tank 23 stores liquid refrigerant between the outdoor unit 2A and the indoor units 3A and 3B, and adjusts refrigerant supply and demand between the units.

  The oil separator 25 includes a refrigerant return pipe 45 for returning the excess oil amount to the refrigerant suction pipe of the compressor 20 when the amount of oil stored in the oil separator 25 is equal to or greater than a predetermined amount, and the oil separator 25 An oil balance pipe 46 for connecting the separator 25 and the oil separator 25 of the other outdoor unit 2B is connected. The oil balance pipe 46 is connected to the oil separator 25 of another outdoor unit 2B via an oil pipe 47, and between the oil separators 25 of the outdoor units 2A and 2B via the oil balance pipe 46 and the oil pipe 47. The oil flows back and forth, and the balance of the amount of oil stored in each oil separator 25 is ensured.

  The outdoor unit 2A includes a temperature sensor that detects an inlet / outlet temperature of the outdoor heat exchanger 21, a pressure sensor SA1 that detects a suction pressure of the compressor 20, a pressure sensor SB1 to SB3 that detects a discharge pressure of the compressor 20, and the like. Various sensors, a plurality of check valves, an outdoor control device 100 for controlling the entire outdoor unit 2A by inputting detection results of the various sensors, and the like are provided. In addition, since the outdoor unit 2B has the same configuration as the outdoor unit 2A, the same portions are denoted by the same reference numerals, and redundant description is omitted. Here, any one of the outdoor units 2A and 2B functions as a parent device, and the outdoor control device 100 (pre-operation change processing means) of the parent device responds to a user instruction input via a remote controller (not shown). Based on this, it communicates with other outdoor control devices 100 and indoor control devices to control the operation of the entire air conditioner 1.

  The indoor unit 3A includes an indoor heat exchanger 10 and an indoor expansion valve 11. One end of the indoor heat exchanger 10 is connected to the liquid pipe 8 via a liquid branch pipe 18 provided with the indoor expansion valve 11. Connected. A branch pipe 12 is connected to the other end of the indoor heat exchanger 10, and the branch pipe 12 branches into a high-pressure gas branch pipe 12A and a low-pressure gas branch pipe 12B. The high-pressure gas branch pipe 12 </ b> A is connected to the high-pressure gas pipe 7 via the first on-off valve 13, and the low-pressure gas branch pipe 12 </ b> B is connected to the low-pressure gas pipe 6 via the second on-off valve 14. Further, a bypass pipe 15 that bypasses the second on-off valve 14 is connected in parallel to the low-pressure gas branch pipe 12B, and a capillary tube 16 and a third on-off valve 17 (balance valve) are connected to the bypass pipe 15. Is provided. In the present embodiment, the first on-off valve 13, the second on-off valve 14, and the third on-off valve 17 are arranged in a solenoid valve kit 19.

  The indoor unit 3A is provided with a temperature sensor that detects the inlet / outlet temperature and room temperature of the outdoor heat exchanger 21, a pressure sensor that detects the refrigerant pressure in the indoor heat exchanger 21, and the like. An indoor control device (not shown) for inputting the result and controlling the indoor unit 3A is provided. In addition, since the indoor unit 3B has substantially the same configuration as the indoor unit 3A, the same portions are denoted by the same reference numerals, and redundant description is omitted.

Next, the operation of the air conditioner 1 will be described.
When all the indoor units 3A and 3B are cooled at the same time, in each outdoor unit 2A and 2B, the switching valve 40 is opened and the four-way valve 41 is controlled to be switched to the solid line position. Also, in each indoor unit 3A and 3B, the first The on-off valve 13 is closed, and the second on-off valve 14 and the third on-off valve 17 are opened. In this case, as indicated by solid line arrows in FIG. 1, the refrigerant discharged from the compressor 20 is supplied to the outdoor heat exchanger 21 via the oil separator 25, where heat is dissipated and condensed to form liquid refrigerant, and the receiver tank 23. And it is supplied to the liquid pipe 8 through the auxiliary cooling circuit 28.

  In the indoor units 3A and 3B, the liquid refrigerant is supplied to the indoor heat exchanger 10 via the liquid pipe 8 via the expansion valve 11, where it absorbs and evaporates to become a low-temperature and low-pressure gas refrigerant. The gas is supplied to the low-pressure gas pipe 6 through the on-off valve 14 and the third on-off valve 17. The gas refrigerant supplied to the low-pressure gas pipe 6 is compressed again by the compressor 20 through the suction pipes 30 of the outdoor units 2A and 2B. As a result, all the indoor units 3A and 3B can simultaneously perform the cooling operation.

  On the other hand, when all the indoor units 3A and 3B are simultaneously heated, the switching valve 40 is closed and the four-way valve 41 is controlled to be switched to the broken line position in each of the outdoor units 2A and 2B. The on-off valve 13 is opened, and the second on-off valve 14 and the third on-off valve 15 are closed. In this case, the high-temperature and high-pressure gas refrigerant discharged from the compressor 20 is supplied to the high-pressure gas pipe 7 via the oil separator 25 as indicated by broken line arrows in FIG.

  In the indoor units 3A and 3B, the gas refrigerant is supplied to the indoor heat exchanger 10 via the high-pressure gas pipe 7, where after the heat is radiated and condensed to become a liquid refrigerant, the refrigerant is supplied via the expansion valve 11. It is supplied to the liquid pipe 8. The liquid refrigerant supplied to the liquid pipe 8 is supplied to the outdoor heat exchanger 21 through the refrigerant pipes 33 and the receiver tank 23 of the outdoor units 2A and 2B, where it absorbs heat and evaporates, where It becomes a gas refrigerant and is compressed again by the compressor 20 through the suction pipe 30. Thereby, the heating operation can be simultaneously performed in all the indoor units 3A and 3B.

  Further, when performing a mixed operation of heating operation and cooling operation, for example, when the indoor unit 3A is operated for heating and the indoor unit 3B is operated for cooling, the outdoor units 2A and 2B are controlled in the same manner as in the above-mentioned simultaneous heating operation. On the other hand, in the indoor unit 3A, the first on-off valve 13 is closed, the second on-off valve 14 and the third on-off valve 17 are opened, and in the indoor unit 3B, the first on-off valve 13 is opened, and the second on-off valve 14 is opened. And the 3rd on-off valve 17 closes. In this case, high-temperature and high-pressure gas refrigerant is supplied from the outdoor units 2A and 2B to the high-pressure gas pipe 7, and in the indoor unit 3A, gas refrigerant is supplied to the indoor heat exchanger 10 via the high-pressure gas pipe 7. After being radiated / condensed to form a liquid refrigerant, it is supplied to the liquid pipe 8 via the expansion valve 11. A part of the liquid refrigerant supplied to the liquid pipe 8 returns to the outdoor units 2A and 2B, absorbs heat and evaporates in the outdoor heat exchanger 21, and becomes a low-temperature and low-pressure gas refrigerant.

  On the other hand, the remainder of the liquid refrigerant supplied to the liquid pipe 8 is supplied to the indoor heat exchanger 10 of the indoor unit 3B, where it absorbs heat and evaporates to become a low-temperature and low-pressure gas refrigerant, and then the second on-off valve 14. And is supplied to the low-pressure gas pipe 6 via the third on-off valve 17. The refrigerant supplied to the low-pressure gas pipe 6 is compressed again by the compressor 20 through the suction pipe 30 together with the gas refrigerant passed through the outdoor heat exchanger 21. Thereby, heating operation and cooling operation can be performed for each of the indoor units 3A and 3B.

  Next, the operation of the operation change preprocessing when the heating operation of the indoor units 3A and 3B is changed to the cooling operation will be described. This operation change pretreatment operation is to control the opening and closing of the first to third on-off valves 13, 14, 17 and the indoor expansion valve 11 under predetermined conditions, thereby suppressing the generation of refrigerant noise and vibration. belongs to. FIG. 2 is a flowchart showing this operation.

  First, the control device 100 determines whether or not a command for stopping the heating operation or changing to the cooling operation is output to any of the indoor units 3A and 3B (step S1). When the command is output, the control device 100 closes the first opening / closing valve 13 of the corresponding indoor unit (for example, the indoor unit 3B) and forcibly sets the opening of the indoor expansion valve 11 of the indoor unit 3B. (Step S2).

  Here, since the second on-off valve 14 and the third on-off valve 17 are closed during the heating operation, all the valves around the indoor heat exchanger 10 are closed by the valve closing operation in step S2. In the indoor heat exchanger 10, a high-temperature and high-pressure gas refrigerant is sealed.

  Subsequently, the control device 100 turns on a timer (not shown) (step S3) and cools the high-temperature and high-pressure gas refrigerant sealed in the indoor heat exchanger 10 (step S4). Specifically, by operating an indoor fan (not shown), heat exchange between room air and the gas refrigerant is promoted to cool the gas refrigerant.

  Subsequently, the control device 100 determines whether or not a first predetermined time (predetermined time) has elapsed from the count value of the timer (step S5). Here, the first predetermined time is a time sufficient for the cooling in step S4 to reduce the pressure of the refrigerant in the indoor heat exchanger 10 to substantially the same pressure as the saturation pressure of the refrigerant at the indoor atmospheric temperature. In the present configuration, the first predetermined time is set to 1 minute 30 seconds based on experiments.

  Subsequently, when the first predetermined time in step S5 has elapsed, the control device 100 operates to open the third on-off valve 17 (step S6). Then, since the pressure of the refrigerant in the indoor heat exchanger 10 is higher than the pressure (low pressure) of the refrigerant in the low-pressure gas pipe 6, the refrigerant in the indoor heat exchanger 10 has a low pressure through the third on-off valve 17. The pressure is balanced by flowing into the gas pipe 6.

  However, even in this case, the refrigerant sealed in the indoor heat exchanger 10 is cooled by the step S4, and the pressure of the refrigerant is lowered to the saturation pressure of the refrigerant at the indoor ambient temperature. The pressure difference between the refrigerant in the indoor heat exchanger 10 and the refrigerant in the low-pressure gas pipe 6 is small. According to this, compared with the conventional case where the high pressure gas refrigerant and the low pressure gas refrigerant are balanced at once, the refrigerant noise and vibration generated when passing through the third on-off valve 17 can be suppressed.

  Subsequently, the control device 100 determines whether or not a second predetermined time has elapsed from the count value of the timer in step S3 (step S7). The second predetermined time is a time sufficient to balance the refrigerant in the outdoor heat exchanger 10 and the refrigerant in the low-pressure gas pipe 6, and is set to 1 minute 30 seconds in this configuration. When the second predetermined time has elapsed, the control device 100 opens the second on-off valve 14 and adjusts the indoor expansion valve 11 to a predetermined opening (step S8), and starts the cooling operation of the indoor unit 3B. (Step S9).

  According to the present embodiment, when the heating operation of the indoor units 3A, 3B is changed to the cooling operation, the first to third on-off valves 13, 14, 17 are closed and the opening of the indoor expansion valve 11 is fully closed. Is controlled so that the high-pressure gas is sealed in the indoor heat exchanger 10. By holding this state for a first predetermined time, the gas refrigerant in the indoor heat exchanger 10 is cooled, and the pressure of this refrigerant drops to the refrigerant saturation pressure at the indoor ambient temperature. . Since the third on-off valve 17 is opened with the refrigerant pressure in the indoor heat exchanger 10 lowered in this manner, the pressure of the refrigerant in the indoor heat exchanger 10 after cooling is high as in the conventional case. Compared with the case where the refrigerant and the low-pressure refrigerant are balanced at a stretch, the pressure difference between the low-pressure and the low-pressure refrigerant is small, so that it is possible to suppress refrigerant noise and vibration generated when balancing.

In the present embodiment, the first predetermined time set in advance as a time sufficient for the pressure of the refrigerant in the indoor heat exchanger 10 to drop to substantially the same pressure as the saturation pressure of the refrigerant at the indoor atmospheric temperature is counted. However, when the first predetermined time has elapsed, the third on-off valve 17 is opened to balance the refrigerant pressure in the low-pressure gas pipe 6. When the refrigerant temperature falls to a temperature substantially equal to the atmospheric temperature in the room where the indoor units 3A and 3B are arranged, the third on-off valve 17 is opened and the low pressure gas pipe 6 is detected. It is good also as a structure balanced with the pressure of an inside refrigerant | coolant.
<Second Embodiment>

  FIG. 3 is a flowchart showing the operation change pre-processing when the heating operation of the indoor units 3A and 3B is changed to the cooling operation in the air conditioner 1 according to the second embodiment. In addition, in this 2nd Embodiment, since the structure of the air conditioning apparatus 1 is the same as that of the said 1st Embodiment, it attaches | subjects the same code | symbol and abbreviate | omits description.

  First, the control device 100 determines whether or not a command for stopping the heating operation or changing to the cooling operation is output to any of the indoor units 3A and 3B (step S11). When the command is output, the control device 100 closes the first opening / closing valve 13 of the corresponding indoor unit (for example, the indoor unit 3B) and forcibly sets the opening of the indoor expansion valve 11 of the indoor unit 3B. (Step S12).

  Here, since the second on-off valve 14 and the third on-off valve 17 are closed during the heating operation, the first to third on-off valves 13, 14, 17 are closed by step S12, and the indoor expansion valve is closed. 11 is opened.

  Subsequently, the control device 100 turns on a timer (not shown) (step S13) and cools the high-temperature and high-pressure gas refrigerant existing in the indoor heat exchanger 10 (step S14). Specifically, by operating an indoor fan (not shown), heat exchange between room air and the gas refrigerant is promoted to cool the gas refrigerant. Then, since the pressure of the gas refrigerant in the indoor heat exchanger 10 is lower than the pressure of the liquid refrigerant in the liquid pipe 8 due to the cooling, the pressure of the liquid refrigerant and the refrigerant in the indoor heat exchanger 10 are reduced. Due to the pressure difference from the pressure, the liquid refrigerant in the liquid pipe 8 flows into the indoor heat exchanger 10, and the inside of the indoor heat exchanger 10 is filled with the liquid refrigerant.

  Subsequently, the control device 100 determines whether or not a third predetermined time has elapsed from the count value of the timer (step S15). Here, the third predetermined time is a time sufficient for the liquid refrigerant in the liquid pipe 8 to flow into the indoor heat exchanger 10 by being cooled in step S14. Is set to 1 minute.

  Subsequently, when the third predetermined time in step S15 has elapsed, the control device 100 forcibly closes the opening of the indoor expansion valve 11 until it is fully closed, and opens the third on-off valve 17 (step S16). Then, the high-pressure liquid refrigerant that has flowed into the indoor heat exchanger 10 flows into the low-pressure gas pipe 6 through the third on-off valve 17 so as to be balanced with the pressure of the refrigerant in the low-pressure gas pipe 6.

  However, even in this case, since the liquid refrigerant has a higher density than the gas refrigerant, the flow rate of the liquid refrigerant flowing through the third on-off valve 17 and the low-pressure gas branch pipe 12B is slower than the flow rate of the gas refrigerant. Since the third on-off valve 17 is opened with the liquid refrigerant flowing into the indoor heat exchanger 10 as described above, the liquid refrigerant becomes the gas refrigerant when the high-pressure refrigerant and the low-pressure refrigerant are balanced. Compared with the case where a gas refrigerant flows, a refrigerant | coolant sound and a vibration can be restrained small compared with the case where a flow velocity becomes slow.

  Subsequently, the control device 100 determines whether or not a fourth predetermined time has elapsed from the count value of the timer in step S13 (step S17). The fourth predetermined time is a time sufficient to balance the refrigerant pressure in the indoor heat exchanger 10 and the refrigerant pressure in the low-pressure gas pipe 6. In the second embodiment, the fourth predetermined time is described above. The predetermined time is set to 1 minute 30 seconds. When the fourth predetermined time has elapsed, the control device 100 opens the second on-off valve 14 and adjusts the indoor expansion valve 11 to a predetermined opening degree (step S18), thereby cooling the indoor unit 3B. Is started (step S19).

  According to the second embodiment, when the heating operation of the indoor units 3A, 3B is changed to the cooling operation, the first to third on-off valves 13, 14, 17 are closed, and the opening degree of the indoor expansion valve 11 is set. By controlling to fully open and maintaining this state for a predetermined third predetermined time, the gas refrigerant in the indoor heat exchanger 10 is cooled, and the pressure of the gas refrigerant is the same as that of the liquid refrigerant in the liquid pipe 6. Lower than pressure. For this reason, the inside of the indoor heat exchanger 10 is in a state where the liquid refrigerant flows in and is filled with the liquid refrigerant. When the third predetermined time elapses, the third on-off valve 17 is opened to balance the high-pressure refrigerant and the low-pressure refrigerant. However, since the liquid refrigerant has a higher density than the gas refrigerant, the third on-off valve 17 and The flow rate of the liquid refrigerant flowing through the low-pressure gas branch pipe 12B is slower than the flow rate of the gas refrigerant. Since the third on-off valve 17 is opened with the liquid refrigerant flowing into the indoor heat exchanger 10 as described above, the liquid refrigerant becomes the gas refrigerant when the high-pressure refrigerant and the low-pressure refrigerant are balanced. Compared with the case where a gas refrigerant flows, a refrigerant | coolant sound and a vibration can be suppressed small compared with the case where a flow velocity becomes slow.

  In the first and second embodiments, the pre-operation change processing operation in the case where the heating operation is changed to the cooling operation has been described. However, this processing operation can also be applied when the heating operation is stopped. Is possible. In this case, in the flowchart shown in FIG. 2, the process of step S1 to step S6 is performed and the process ends. Moreover, in the flowchart shown in FIG. 3, the process of step S11-step S16 is performed, and it complete | finishes.

It is a refrigerant circuit figure showing one embodiment of the air harmony device concerning the present invention. It is a flowchart which shows the operation | movement of a driving | operation change pre-process. It is a flowchart which shows the operation | movement of the driving | operation change pre-processing concerning 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2A, 2B Outdoor unit 3A, 3B Indoor unit 5 Inter-unit piping 6 Low pressure gas pipe 7 High pressure gas pipe 8 Liquid pipe 10 Indoor heat exchanger 11 Indoor expansion valve 12A High pressure gas branch pipe 12B Low pressure gas branch pipe 13 1 on-off valve 14 second on-off valve 17 third on-off valve (balance valve)
18 Liquid Branch Pipe 20 Compressor 21 Outdoor Heat Exchanger 30 Refrigerant Suction Pipe 31 Refrigerant Discharge Pipe 100 Controller (Operation Change Pre-Processing Means)

Claims (2)

An outdoor unit having a compressor, an outdoor heat exchanger and an outdoor expansion valve, and a plurality of indoor units having an indoor heat exchanger and an indoor expansion valve are connected by inter-unit piping, and one end of the outdoor heat exchanger Is connected alternatively to the refrigerant discharge pipe and the refrigerant suction pipe of the compressor, and the inter-unit pipe is connected to the high-pressure gas pipe connected to the refrigerant discharge pipe and the refrigerant suction pipe A low-pressure gas pipe and a liquid pipe connected to the other end of the outdoor heat exchanger are configured, and one end of the indoor heat exchanger is connected to the high-pressure gas pipe and the low-pressure gas pipe, respectively. And the other end is connected to the liquid pipe through a liquid branch pipe, and the high-pressure gas branch pipe and the low-pressure gas branch pipe are each provided with on-off valves, and the low-pressure gas branch pipe is connected to the liquid pipe. A balance valve is provided in parallel with the open / close valve of the pipe. A plurality of the indoor units can be cooled or heated at the same time, or the cooling operation and the heating operation can be mixedly performed, and the heating operation of any of the indoor units is stopped, or When changing to cooling operation, the on-off valve provided in the high-pressure gas branch pipe, the on-off valve provided in the low-pressure gas branch pipe, and the balance valve are closed , the indoor expansion valve is opened, and The indoor fan is operated toward the indoor heat exchanger, this state is maintained for a predetermined time, and the indoor heat exchanger is filled with liquid refrigerant, and then the indoor expansion valve is closed and the low-pressure gas branch pipe is connected. An air conditioning apparatus comprising an operation change pre-processing means for opening a provided balance valve. The air conditioner according to claim 1 , wherein the predetermined time is a time set in advance as a time sufficient for the liquid refrigerant in the liquid pipe to flow into the indoor heat exchanger.

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