JP2013170718A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner which can perform proper pressure equalization control according to a refrigeration cycle state.SOLUTION: For switching from a reverse defrosting operation to a heating-dominant operation in an air conditioner 1, outdoor units 2a-2c stop compressors 21a-21c, open electromagnetic valves 44a-44c for bypass, and switch four-way valves 22a-22c. According to a pressure difference between a discharge pressure detected by a high pressure sensor 50 and an inlet pressure detected by a low pressure sensor 51 in the outdoor units 2a-2c, pressure increase control by switching units 6a, 6b corresponding to indoor units 8a, 8b for performing heating operations and pressure decrease control by switching units 6c, 6d corresponding to the indoor units 8c, 8d for performing cooling operations are canceled or disabled.

Description

  The present invention relates to an air conditioner in which a plurality of indoor units are connected to at least one outdoor unit by refrigerant piping, and a cooling operation and a heating operation can be selected for each indoor unit.

  Conventionally, there has been proposed an air conditioner capable of performing a so-called cooling / heating-free operation in which a plurality of indoor units are connected to at least one outdoor unit by refrigerant piping, and a cooling operation and a heating operation can be selected for each indoor unit. Has been. For example, an air conditioner described in Patent Literature 1 includes a single outdoor unit including a compressor, a flow path switching unit, an outdoor heat exchanger, and an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve. It has three indoor units and a shunt unit with a high-pressure side indoor switching valve and a low-pressure side indoor expansion valve, which are connected to each other by a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe Thus, a refrigerant circuit of the air conditioner is formed.

  One end of the high-pressure side indoor switching valve provided in the diversion unit is connected to the high-pressure gas pipe by a refrigerant pipe, and the other end is connected to the indoor heat exchanger by a refrigerant pipe. Moreover, one end of the low-pressure side indoor switching valve is connected to the low-pressure gas pipe by a refrigerant pipe, and the other end is connected to the indoor heat exchanger by a refrigerant pipe. By opening and closing these two types of indoor side switching valves, the indoor heat exchanger and the high pressure gas pipe can be communicated with each other, or the indoor heat exchanger and the low pressure gas pipe can be communicated with each other. If the high-pressure gas pipe is connected, the indoor heat exchanger functions as a condenser and heating operation can be performed. If the indoor heat exchanger and the low-pressure gas pipe are connected, the indoor heat exchanger functions as an evaporator. Cooling operation can be performed. Therefore, by operating each indoor switching valve of the diversion unit, heating operation or cooling operation can be selected for each indoor unit.

  In the air conditioner as described above, when the indoor unit is switched from the heating operation to the cooling operation, or when the indoor unit is switched from the cooling operation to the heating operation, the refrigerant pressure in the refrigerant pipe connecting the indoor heat exchanger and the flow dividing unit is reduced. There is a risk that the refrigerant changes suddenly, and as a result, the refrigerant flows rapidly through the high-pressure side indoor switching valve and the low-pressure side indoor switching valve. Then, when the refrigerant suddenly flows through the high-pressure side indoor switching valve and the low-pressure side indoor switching valve, there is a possibility that an abnormal noise (refrigerant flow sound) may occur, which may cause discomfort to the user.

  Therefore, in the above air conditioner, the high-pressure side bypass pipe connected in parallel to the high-pressure side indoor switching valve and incorporating the high-pressure side solenoid valve, and the low-pressure side connected in parallel to the low-pressure side indoor switching valve and built-in the low-pressure side solenoid valve A side bypass pipe is provided in the shunt unit, and pressure equalization control described below is performed using these. When the indoor unit is switched from the heating operation to the cooling operation, the high pressure side indoor switching valve and the indoor expansion valve are closed, and the low pressure side electromagnetic valve is opened and left for a predetermined time. Thereby, the low pressure gas pipe side of the low pressure side indoor switching valve and the indoor heat exchanger side are communicated with each other by the low pressure side bypass pipe, and the refrigerant pressure on the indoor heat exchanger side of the low pressure side indoor switching valve is reduced. When the low-pressure side indoor switching valve is opened to start operation, it is possible to suppress the generation of noise due to the difference in refrigerant pressure between the low-pressure gas pipe side and the indoor heat exchanger side of the low-pressure side indoor switching valve.

  When the indoor unit is switched from the cooling operation to the heating operation, the low pressure side indoor switching valve and the indoor expansion valve are closed, and the high pressure side electromagnetic valve is opened and left for a predetermined time. Thereby, the high pressure gas pipe side of the high pressure side indoor switching valve and the indoor heat exchanger side are communicated with each other by the high pressure side bypass pipe, and the refrigerant pressure on the indoor heat exchanger side of the high pressure side indoor switching valve is increased. When the high pressure side indoor switching valve is opened to start the operation, it is possible to suppress the generation of noise due to the difference in refrigerant pressure between the high pressure gas pipe side of the high pressure side indoor switching valve and the indoor heat exchanger side.

Japanese Patent Laid-Open No. 5-203275 (pages 3-4, FIG. 1)

  When performing the pressure equalization control described above, the high-pressure side indoor switching valve or the low-pressure side indoor switching valve and the indoor expansion valve operation of the indoor unit are closed, so that the operation of the indoor unit is stopped during the pressure equalization control. As a result, the room where the indoor unit is installed is not air-conditioned. Therefore, it is desirable to finish the pressure equalization control in as short a time as possible.

  On the other hand, in the air conditioner as described above, when the compressor can be stopped and the refrigeration cycle can be switched, for example, the outdoor heat exchanger functions as a condenser and the indoor heat exchangers of all indoor units are evaporated. In some cases, the reverse defrosting operation or reverse oil recovery operation performed by functioning as an evaporator is switched to the heating operation performed by functioning an outdoor heat exchanger as an evaporator. In this case, for example, by opening an electromagnetic valve incorporated in a bypass pipe that bypasses the high pressure side and the low pressure side of the compressor, the high pressure side and the low pressure side of the compressor can be communicated with each other. If the high-pressure side and the low-pressure side are communicated, the pressure equalization control can be completed in a shorter time than when the compressor is operating. In this way, when the compressor can be stopped and the refrigeration cycle can be switched, if the same pressure equalization control as when the compressor is operating is performed, the indoor unit will be stopped for a longer time than necessary, There was a risk of impairing the user's comfort.

  The present invention solves the above-described problems, and an object of the present invention is to provide an air conditioner that can perform appropriate pressure equalization control according to the state of the refrigeration cycle.

  In order to solve the above-described problems, an air conditioner of the present invention includes a compressor, an outdoor heat exchanger, an outside air temperature detecting means for detecting the outside air temperature, and a high pressure detection for detecting the discharge pressure of the refrigerant discharged from the compressor. And a plurality of indoor units having an indoor heat exchanger and an indoor unit pressure-reducing means, and a plurality of indoor units having a low-pressure detecting means for detecting the suction pressure of the refrigerant sucked into the compressor and the refrigerant Provided with a plurality of switching units provided corresponding to the units and switching the flow direction of the refrigerant in the indoor heat exchanger, wherein the outdoor unit and the plurality of switching units are connected by a high-pressure gas pipe and a low-pressure gas pipe. The plurality of indoor units are connected to at least one outdoor unit by a liquid pipe, and the corresponding plurality of indoor units and a plurality of switching units are connected by a refrigerant pipe. In addition, the switching unit includes a pressure equalizing unit that performs a pressure equalizing process for increasing or decreasing the refrigerant pressure in the indoor heat exchanger provided in the indoor unit in accordance with an instruction from the corresponding indoor unit. The discharge pressure detected by the high pressure detecting means when switching from the state where the outdoor heat exchanger functions as a condenser to perform the defrosting operation or oil recovery operation to the state where the outdoor heat exchanger functions as an evaporator is performed. If the pressure difference between the suction pressure detected by the low pressure detection means is equal to or less than a predetermined value, the pressure equalization processing by the pressure equalization means is not performed. In addition, if the pressure difference between the discharge pressure and the suction pressure is equal to or less than a predetermined value during the pressure equalization process, the pressure equalization process is stopped.

  The air conditioner of the present invention configured as described above does not perform pressure equalization processing if the pressure difference between the discharge pressure and the suction pressure is equal to or less than a predetermined value. If the pressure difference between the discharge pressure and the suction pressure is equal to or less than a predetermined value during the pressure equalization process, the pressure equalization process is stopped. Therefore, the time for performing the pressure equalization process can be shortened, and the return from the defrosting operation or the oil recovery operation to the air conditioning operation can be accelerated.

It is a refrigerant circuit figure explaining the flow of the refrigerant in the case of performing heating main operation in the example of the present invention. FIG. 3 is a configuration explanatory diagram of a switching unit in the embodiment of the present invention. It is the switching unit operation | movement table which defined operation | movement of each valve with which the switching unit was provided in the Example of this invention. It is a refrigerant circuit figure explaining the flow of the refrigerant in the case of performing the defrost operation in the example of the present invention. It is a refrigerant circuit figure at the time of returning from a defrost operation to a heating main operation in the Example of this invention. It is a flowchart explaining the process in the outdoor unit at the time of performing a defrost operation in the Example of this invention, (A) demonstrates the process in the outdoor unit in which the defrost operation start conditions were satisfied, (B) Fig. 4 illustrates processing in the outdoor unit that performs control according to an instruction from the outdoor unit in which the defrosting operation start condition is satisfied. It is a flowchart explaining the process in the indoor unit at the time of performing the defrost operation in the Example of this invention.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. As an embodiment, three outdoor units and four indoor units are connected to each other by refrigerant piping, and a so-called cooling / heating-free operation can be performed in which a cooling operation and a heating operation can be selected for each indoor unit. An air conditioning apparatus will be described as an example. The present invention is not limited to the following embodiments, and can be variously modified without departing from the gist of the present invention.

  As shown in FIG. 1, the air conditioner 1 according to the present embodiment includes three outdoor units 2a to 2c, four indoor units 8a to 8d, four switching units 6a to 6d, and a branching unit 70. , 71, 72. The outdoor units 2a to 2c, the indoor units 8a to 8d, the switching units 6a to 6d, the branching units 70, 71 and 72, the high pressure gas pipe 30, the high pressure gas distribution pipes 30a to 30c, the low pressure gas pipe 31, and the low pressure The refrigerant circuit of the air conditioner 1 is comprised by mutually connecting with the gas distribution pipes 31a-31c, the liquid pipe 32, and the liquid distribution pipes 32a-32c.

  In this air conditioner 1, heating operation (all indoor units are in heating operation), heating main operation is performed by opening and closing and switching various valves provided in the outdoor units 2a to 2c and the switching units 6a to 6d. (When the overall capacity required for an indoor unit performing heating operation exceeds the total capacity required for an indoor unit performing cooling operation), cooling operation (all indoor units are cooling operation), cooling-dominated operation Various operation operations are possible, such as when the entire capacity required for the indoor unit performing the cooling operation exceeds the total capacity required for the indoor unit performing the heating operation.

  FIG. 1 shows a refrigerant circuit in the case where a heating main operation is performed from among these operation operations. First, the configuration of the outdoor units 2a to 2c will be described with reference to FIG. 1, but since the configurations of the outdoor units 2a to 2c are all the same, only the configuration of the outdoor unit 2a will be described in the following description. Detailed description of the unit 2b and the outdoor unit 2c is omitted.

  As shown in FIG. 1, the outdoor unit 2a includes a compressor 21a, a four-way valve 22a, an outdoor heat exchanger 23a, an outdoor fan 24a, an accumulator 25a, an outdoor unit high-pressure gas pipe 33a, and an outdoor unit low-pressure gas. Pipe 34a, outdoor unit liquid pipe 35a, hot gas bypass pipe 36a, refrigerant pipes 37a, 38a, 39a, closing valves 40a, 41a, 42a, outdoor expansion valve 43a, and bypass unit as an outdoor unit opening / closing means And an electromagnetic valve 44a.

  The compressor 21a is a variable capacity compressor that can vary its operating capacity by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. The discharge side of the compressor 21a is connected to the closing valve 40a by the outdoor unit high-pressure gas pipe 33a. The suction side of the compressor 21a is connected to the outflow side of the accumulator 25a by a refrigerant pipe 39a, and the inflow side of the accumulator 25a is connected to the closing valve 41a by an outdoor unit low-pressure gas pipe 34a.

  The four-way valve 22a is a valve for switching the direction in which the refrigerant flows, and includes four ports a, b, c, and d. A refrigerant pipe connected to the outdoor unit high-pressure gas pipe 33a at the connection point A is connected to the port a. The port b and the outdoor heat exchanger 23a are connected by a refrigerant pipe 37a, and the refrigerant pipe 38a connected to the port c is connected to the outdoor unit low-pressure gas pipe 34a at a connection point B. The port d is sealed.

  The outdoor heat exchanger 23a exchanges heat between the refrigerant and the outside air taken into the outdoor unit 2a by an outdoor fan 24a described later, and one end of the outdoor heat exchanger 23a is connected to the four-way valve 22a as described above. The port b is connected by a refrigerant pipe 37a, and the other end is connected by a refrigerant pipe to one port of the outdoor expansion valve 43a. The other port of the outdoor expansion valve 43a is connected to the closing valve 42a by an outdoor unit liquid pipe 35a. The outdoor heat exchanger 23a functions as a condenser when the air-conditioning apparatus 1 performs cooling / cooling main operation, and functions as an evaporator when performing heating / heating main operation.

  The outdoor fan 24a is a propeller fan formed of a resin material disposed in the vicinity of the outdoor heat exchanger 23a. The outdoor fan 24a is rotated by a fan motor (not shown) to take outside air into the outdoor unit 2a, and the outdoor heat exchanger After the refrigerant and the outside air are heat-exchanged in 23a, the heat-exchanged outside air is discharged to the outside of the outdoor unit 2a.

  The accumulator 25a has an inflow side connected to the outdoor unit low-pressure gas pipe 34a, and an outflow side connected to the suction side of the compressor 21a through a refrigerant pipe 39a. The accumulator 25a separates the inflowing refrigerant into a gas refrigerant and a liquid refrigerant, and causes only the gas refrigerant to be sucked into the compressor 21a.

  One end of the hot gas bypass pipe 36a is connected to the outdoor unit high pressure gas pipe 33a at a connection point C, and the other end is connected to the outdoor unit low pressure gas pipe 34a at a connection point D. A bypass electromagnetic valve 44a is incorporated in the hot gas bypass pipe 36a, and the refrigerant flows or does not flow through the hot gas bypass pipe 36a by opening and closing the bypass electromagnetic valve 44a.

  In addition to the configuration described above, the outdoor unit 2a is provided with various sensors. As shown in FIG. 1, between the discharge port of the compressor 21a and the connection point C in the outdoor unit high-pressure gas pipe 33a, high pressure is high pressure detection means for detecting the discharge pressure of the refrigerant discharged from the compressor 21a. A sensor 50a and a discharge temperature sensor 53a for detecting the temperature of the refrigerant discharged from the compressor 21a are provided. Further, between the connection point D in the outdoor unit low-pressure gas pipe 34a and the inlet of the accumulator 25a, a low-pressure sensor 51a which is a low-pressure detection means for detecting the suction pressure of the refrigerant sucked into the compressor 21a, and the compressor A suction temperature sensor 54a for detecting the temperature of the refrigerant sucked into 21a is provided. Further, between the outdoor expansion valve 43a and the closing valve 42a in the outdoor unit liquid pipe 35a, an intermediate pressure sensor 52a that detects the pressure of the refrigerant flowing through the outdoor unit liquid pipe 35a, and the refrigerant flowing through the outdoor unit liquid pipe 35a. A refrigerant temperature sensor 55a for detecting the temperature is provided.

  The refrigerant pipe 37a is provided with a heat exchange temperature sensor 56a for detecting the temperature of the refrigerant flowing out of the outdoor heat exchanger 23a or flowing into the outdoor heat exchanger 23a. Also, an outdoor air temperature sensor 57a, which is an outdoor air temperature detecting means for detecting the temperature of the outdoor air flowing into the outdoor unit 2a, that is, the outdoor air temperature, is provided in the vicinity of the outside air inlet (not shown) of the outdoor unit 2a.

  The outdoor unit 2a is provided with a control unit 100a. The control unit 100a is mounted on a control board stored in an electrical component box (not shown) of the outdoor unit 2a, and includes a CPU 110a, a storage unit 120a, and a communication unit 130a. CPU110a takes in the detection signal from each sensor mentioned above of outdoor unit 2a, and takes in the control signal outputted from each indoor unit 8a-8d via communication part 130a. The CPU 110a performs various controls related to the operation of the outdoor unit 2a such as rotation control of the compressor 21a and the outdoor fan 24a, switching control of the four-way valve 22a, and opening degree control of the outdoor expansion valve 43a based on the detected detection signal and control signal. I do.

  The storage unit 120a is composed of a ROM and a RAM, and stores detection values corresponding to control programs for the outdoor unit 2a and detection signals from each sensor. The communication unit 130a is an interface that mediates communication between the outdoor unit 2a and the indoor units 8a to 8d.

  As mentioned above, although the structure of the outdoor unit 2a was demonstrated, the structure of the outdoor unit 2b and the outdoor unit 2c is the same as the outdoor unit 2a, and the end of the number given to the component (apparatus and member) of the outdoor unit 2a from a What changed into b or c becomes the component of the outdoor unit 2b and the outdoor unit 2c corresponding to the component of the outdoor unit 2a. However, the symbols of the outdoor unit 2a, the outdoor unit 2b, and the outdoor unit 2c are different for the connection points of the four-way valve ports and the refrigerant pipes, and the ports a, b, c in the four-way valve 22a of the outdoor unit 2a are different. , D are ports e, f, g, h for the four-way valve 22b of the outdoor unit 2b, and ports j, k, m, n for the four-way valve 22c of the outdoor unit 2c. Further, in the outdoor unit 2b, the connection points E, F, G, H corresponding to the connection points A, B, C, and D in the outdoor unit 2a, and the connection points J, K, M, and N in the outdoor unit 2c, respectively. It is said.

  Next, the configuration of the four indoor units 8a to 8d will be described with reference to FIG. Since the configurations of the indoor units 8a to 8d are all the same, in the following description, only the configuration of the indoor unit 8a will be described, and description of the other indoor units 8b to 8d will be omitted.

  The indoor unit 8a includes an indoor heat exchanger 81a, an indoor expansion valve 82a that is an indoor unit decompression unit, an indoor fan 83a, refrigerant pipes 87a and 88a, and closing valves 44a and 45a. One end of the indoor heat exchanger 81a is connected to one port of the indoor expansion valve 82a by a refrigerant pipe, and the other end is connected to the closing valve 45a by a refrigerant pipe. The indoor heat exchanger 81a functions as an evaporator when the indoor unit 8a performs a cooling operation, and functions as a condenser when the indoor unit 8a performs a heating operation.

  As described above, the indoor expansion valve 82a has one port connected to the indoor heat exchanger 81a via the refrigerant pipe, and the other port connected to one port of the closing valve 44a via the refrigerant pipe 87a. One end of the refrigerant pipe 88a is connected to the other port of the closing valve 44a. When the indoor heat exchanger 81a functions as an evaporator, the indoor expansion valve 82a is adjusted according to the required cooling capacity, and when the indoor heat exchanger 81a functions as a condenser, The opening is adjusted according to the required heating capacity.

  The indoor fan 83a is a cross-flow fan formed of a resin material, and is rotated by a fan motor (not shown) to take indoor air into the indoor unit 8a and heat the refrigerant and indoor air in the indoor heat exchanger 81a. After the exchange, the heat exchanged air is supplied to the room.

  In addition to the configuration described above, the indoor unit 8a is provided with various sensors. The refrigerant pipe on the indoor expansion valve 82a side of the indoor heat exchanger 81a is provided with a refrigerant temperature sensor 84a that detects the temperature of the refrigerant flowing into or out of the indoor heat exchanger 81a. In addition, a refrigerant temperature sensor 85a for detecting the temperature of the refrigerant flowing into or out of the indoor heat exchanger 81a is provided in the refrigerant pipe on the closing valve 45a side of the indoor heat exchanger 81a. Furthermore, a room temperature sensor 86a for detecting the temperature of the indoor air flowing into the indoor unit 8a, that is, the room temperature, is provided in the vicinity of the indoor air inlet (not shown) of the indoor unit 8a.

  The indoor unit 8a includes a control unit 800a. The control unit 800a is mounted on a control board stored in an electrical component box (not shown) of the indoor unit 8a, and includes a CPU 810a, a storage unit 820a, and a communication unit 830a. The CPU 810a captures detection signals from the above-described sensors of the indoor unit 8a and captures control signals output from the outdoor units 2a to 2d via the communication unit 830a. The CPU 810a performs various controls related to the operation of the indoor unit 8a, such as rotation control of the indoor fan 83a and opening control of the indoor expansion valve 82a, based on the acquired detection signal and control signal.

The storage unit 820a includes a ROM and a RAM, and stores detection values corresponding to control programs for the indoor unit 8a and detection signals from the sensors. The communication unit 830a is an interface that mediates communication between the indoor unit 8a and the outdoor units 2a to 2c.
The control units 100a to 100c of the outdoor units 2a to 2c and the control units 800a to 800d of the indoor units 8a to 8d are connected to each other via the communication units 130a to 130c and the communication units 830a to 830d. ing.

  Although the configuration of the indoor unit 8a has been described above, the configuration of the indoor units 8b to 8d is the same as that of the indoor unit 8a, and the end of the numbers assigned to the components (devices and members) of the indoor unit 8a are a to b, The components changed to c and d are the components of the indoor units 8b to 8d corresponding to the components of the outdoor unit 8a.

  Next, the configuration of the four switching units 6a to 6d will be described with reference to FIGS. The air conditioner 1 includes four switching units 6a to 6d corresponding to the four indoor units 8a to 8d. In addition, since all the structures of switching unit 6a-6d are the same, in the following description, only the structure of switching unit 6a is demonstrated, and description is abbreviate | omitted about the other switching units 6b-6d.

  The switching unit 6a includes a first opening / closing means 61a, a second opening / closing means 62a, a third opening / closing means 63a, a fourth opening / closing means 64a, a first capillary tube 65a serving as a flow restricting means, and a second capillary tube 66a. Closing valves 67a, 68a, 69a, a first branch pipe 91a, a second branch pipe 92a, a third branch pipe 93a, a fourth branch pipe 94a, a fifth branch pipe 95a, and a bypass pipe 96a And a refrigerant pipe 97a.

  One end of the first branch pipe 91a is connected to one port of the closing valve 67a, and one end of the second branch pipe 92a is connected to one port of the closing valve 68a. Further, the other end of the first branch pipe 91a and the other end of the second branch pipe 92a are connected to each other at a connection point Ta. One end of the refrigerant pipe 97a is connected to one port of the closing valve 69a, and the other end of the refrigerant pipe 97a is connected to the other end of the first branch pipe 91a and the other end of the second branch pipe 92a. Connected with Ta. The other port of the closing valve 67a has a high-pressure gas pipe 30, the other port of the closing valve 68a has a low-pressure gas pipe 31, and the other port of the closing valve 69a has the other end of the refrigerant pipe 88a. Are connected to each other.

  One end of the third branch pipe 93a is connected to the first branch pipe 91a at the connection point Qa, and one end of the fourth branch pipe 94a is connected to the second branch pipe 92a at the connection point Sa. Further, the other end of the third branch pipe 93a and the other end of the fourth branch pipe 94a are connected to each other at a connection point Ra.

  The fifth branch pipe 95a has one end connected to the third branch pipe 93a and the fourth branch pipe 94a at the connection point Ra, and the other end connected to the first branch pipe 91a, the second branch pipe 92a, and the refrigerant pipe 97a at the connection point Ta. It is connected to the. The bypass pipe 96a has one end connected to the first branch pipe 91a at the connection point Pa and the other end connected to the third branch pipe 93a, the fourth branch pipe 94a, and the fifth branch pipe 95a at the connection point Ra. Has been.

  A first opening / closing means 61a is incorporated in the first branch pipe 91a, and a second opening / closing means 62a is incorporated in the second branch pipe 92a. The first opening / closing means 61a and the second opening / closing means 62a are constituted by, for example, electromagnetic valves. When the first opening / closing means 61a is opened and the second opening / closing means 62a is closed, the indoor heat exchanger 81a of the indoor unit 8a corresponding to the switching unit 6a is connected to the discharge side (high-pressure gas pipe 30 side) of the compressor 21. Thus, the indoor heat exchanger 81a functions as a condenser. When the second opening / closing means 62a is opened and the first opening / closing means 61a is closed, the indoor heat exchanger 81a of the indoor unit 8a corresponding to the switching unit 6a is connected to the suction side (low-pressure gas pipe 31 side) of the compressor 21. The indoor heat exchanger 81a functions as an evaporator.

  The third branch pipe 93a has a third opening / closing means 63a, the fourth branch pipe 94a has a fourth opening / closing means 64a, the fifth branch pipe 95a has a first capillary tube 65a, and the bypass pipe 96a has a second capillary. Tubes 66a are respectively incorporated. The third opening / closing means 63a and the fourth opening / closing means 64a are constituted by, for example, electromagnetic valves. By opening the third opening / closing means 63a, the first branch pipe 91a and the refrigerant pipe 97a communicate with each other through the third branch pipe 93a and the fifth branch pipe 95a. Further, by opening the fourth opening / closing means 64a, the second branch pipe 92a and the refrigerant pipe 97a communicate with each other through the fourth branch pipe 94a and the fifth branch pipe 95a.

  The switching unit 6a has been described above, but the configuration of the switching units 6b to 6d is the same as that of the switching unit 6a, and the numbers given to the components (devices and members) of the switching unit 6a are suffixed with a, b, c, The components changed to d and d are components of the switching units 6b to 6d corresponding to the components of the switching unit 6a. The third opening / closing means 63a to 63d, the fourth opening / closing means 64a to 64d, the first capillary tubes 65a to 65d, the third branch pipes 93a to 93d, the fourth branch pipes 94a to 94d, and the fifth branch stream. The pipes 95a to 95d constitute the pressure equalizing means of the present invention.

  Next, the outdoor units 2a to 2c, the indoor units 8a to 8d and the switching units 6a to 6d described above, the high pressure gas pipe 30, the high pressure gas distribution pipes 30a to 30c, the low pressure gas pipe 31, the low pressure gas distribution pipes 31a to 31c, the liquid The connection state with the pipe | tube 32, the liquid distribution pipes 32a-32c, and the branch devices 70, 71, and 72 is demonstrated using FIG. One ends of the high-pressure gas branch pipes 30a to 30c are connected to the shutoff valves 40a to 40c of the outdoor units 2a to 2c, respectively, and the other ends of the high-pressure gas branch pipes 30a to 30c are all connected to the branching device 70. One end of the high-pressure gas pipe 30 is connected to the branching device 70, and the other end of the high-pressure gas pipe 30 is branched and connected to the closing valves 67a to 67d of the switching units 6a to 6d.

  One end of each of the low pressure gas distribution pipes 31a to 31c is connected to each of the closing valves 41a to 41c of the outdoor units 2a to 2c, and the other end of each of the low pressure gas distribution pipes 31a to 31c is connected to the branching device 71. One end of the low-pressure gas pipe 31 is connected to the branching device 71, and the other end of the low-pressure gas pipe 31 is branched and connected to the closing valves 68a to 68d of the switching units 6a to 6d.

One ends of the liquid pipes 32a to 32c are connected to the closing valves 42a to 42c of the outdoor units 2a to 2c, respectively, and the other ends of the liquid pipes 32a to 32c are all connected to the branching device 72. One end of the liquid pipe 32 is connected to the branching device 72, and the other end of the liquid pipe 32 is branched and connected to the closing valves 44a to 44d of the indoor units 8a to 8d, respectively. Further, the closing valves 45a to 45d of the indoor units 8a to 8d and the corresponding closing valves 69a to 69d of the switching units 6a to 6d are connected by refrigerant pipes 88a to 88d.
With the connection described above, the refrigerant circuit of the air conditioner 1 is configured, and the refrigeration cycle is established by flowing the refrigerant through the refrigerant circuit.

  Next, the operation | movement operation | movement of the air conditioning apparatus 1 in a present Example is demonstrated using FIG. In the following description, hatching is given when each heat exchanger provided in the outdoor units 2a to 2c and the indoor units 8a to 8d is a condenser, and white is illustrated when the heat exchanger is an evaporator. The bypass solenoid valves 44a to 44c provided in the outdoor units 2a to 2c, the first opening / closing means 61a to 61d, the second opening / closing means 62a to 62d, and the third opening / closing means 63a provided to the switching units 6a to 6d. ˜63d and the open / closed states of the fourth opening / closing means 64a to 64d are shown in black when they are closed and white when they are open. Moreover, the arrow has shown the flow of the refrigerant | coolant.

  As shown in FIG. 1, heating is performed when two indoor units 8a and 8b perform heating operation and the remaining indoor units 8c and 8d perform cooling operation among the four indoor units 8a to 8d. If the overall capacity required by the two indoor units 8a and 8b that are in operation exceeds the overall capacity required by the indoor units 8c and 8d that are performing the cooling operation, the air conditioner 1 is the heating main It becomes driving. In addition, in the following description, since the whole driving | operation capability requested | required with indoor unit 8a-8d is large, the case where all the outdoor units 2a-2c are drive | operated is demonstrated.

  Specifically, the CPU 110a of the outdoor unit 2a switches the four-way valve 22a so that the port a and the port d communicate with each other and the port b and the port c communicate with each other. As a result, the refrigerant pipe 37a is connected to the outdoor unit low-pressure gas pipe 34a via the refrigerant pipe 38a, the outdoor heat exchanger 23a is connected to the suction side of the compressor 21a, and the outdoor heat exchanger 23a functions as an evaporator. It becomes like this. Similarly, the CPU 110b of the outdoor unit 2b switches the four-way valve 22b so that the port e and the port h communicate with each other and the port f and the port g communicate with each other, and the outdoor heat exchanger 23b serves as an evaporator. The CPU 110c of the outdoor unit 2c switches the four-way valve 22c so that the port j and the port n communicate with each other and the port k and the port m communicate with each other, and the outdoor heat exchanger 23c evaporates. To function as a container.

  The CPUs 810a, 810b of the indoor units 8a, 8b that perform the heating operation open the first opening / closing means 61a, 61b and the third opening / closing means 63a, 63b of the corresponding switching units 6a, 6b, respectively, and the first branch pipe 91a, 91b and the third branch pipes 93a and 93b are allowed to flow the refrigerant, and the second opening and closing means 62a and 62b and the fourth opening and closing means 64a and 64b are closed to make the second branch pipes 92a and 92b and the fourth branch pipe 94a, The refrigerant is prevented from flowing through 94b. Thereby, the closing valves 67a and 67b of the switching units 6a and 6b communicate with the closing valves 69a and 69b, and the indoor heat exchangers 81a and 81b of the indoor units 8a and 8b function as a condenser.

  On the other hand, the CPUs 810c, d of the indoor units 8c, 8d performing the cooling operation close the first opening / closing means 61c, 61d and the third opening / closing means 63c, 63d of the switching units 6c, 6d, respectively, The refrigerant is prevented from flowing through the 91c, 91d and the third branch pipes 93c, 93d, and the second opening / closing means 62c, 62d and the fourth opening / closing means 64c, 64d are opened to open the second branch pipes 92c, 92d and the fourth branch flow. The refrigerant is allowed to flow through the tubes 94c and 94d. Thereby, the closing valves 68c and 68d of the switching units 6c and 6d communicate with the closing valves 69c and 69d, and the indoor heat exchangers 81c and 81d of the indoor units 8c and 8d function as an evaporator.

  The high-pressure refrigerant discharged from the compressors 21a to 21c flows through the outdoor unit high-pressure gas pipes 33a to 33c, and flows into the high-pressure gas branch pipes 30a to 30c through the closing valves 40a to 40c. At this time, since the bypass solenoid valves 44a to 44c are closed, the refrigerant discharged from the compressors 21a to 21c flows from the outdoor unit high pressure gas pipes 33a to 33c through the hot gas bypass pipes 36a to 36c. It does not flow into the low pressure gas pipes 34a to 34c.

  The refrigerant that has flowed into the high-pressure gas branch pipes 30a to 30c merges at the branching device 70, flows into the high-pressure gas pipe 30, and flows from the high-pressure gas pipe 30 into the switching units 6a and 6b. The refrigerant flowing into the switching units 6a and 6b flows through the first branch pipes 91a and 91b provided with the first opening / closing means 61a and 61b that are open, flows out of the switching units 6a and 6b, and flows into the refrigerant pipes 88a and 88b. It flows through the indoor units 8a and 8b through 88b. At this time, the amount of refrigerant flowing into the bypass pipes 96a and 96b from the first branch pipes 91a and 91b via the connection points Pa and Pb is reduced in the first branch pipes 91a and 91b due to the presence of the second capillary tubes 66a and 66b. The amount of refrigerant flowing is very small. Further, since the third opening / closing means 93a, 93b are open and the fourth opening / closing means 94a, 94b are closed, the connection points Qa, Qb and the connection points Ta, Tb are in communication with each other. Since the first capillary tubes 95a and 95b exist between them, the amount of refrigerant flowing into the third branch pipes 93a and 93b from the first branch pipes 91a and 91b through the connection points Qa and Qb is the first branch pipe. The amount of refrigerant flowing through 91a and 91b is negligible.

  The refrigerant that has flowed into the indoor units 8a and 8b flows into the indoor heat exchangers 81a and 81b, exchanges heat with indoor air, and condenses, thereby heating the room in which the indoor units 8a and 8b are installed. . The refrigerant that has flowed out of the indoor heat exchangers 81a and 81b passes through the indoor expansion valves 82a and 82b incorporated in the refrigerant pipes 87a and 87b, and is reduced in pressure to become an intermediate pressure refrigerant. The CPUs 810a and 810b of the indoor units 8a and 8b are the indoor heat exchangers 81a and 81b, which are condensers, from the refrigerant temperature detected by the refrigerant temperature sensors 84a and 84b and the high-pressure saturation temperature received from the outdoor units 2a to 2c. The degree of refrigerant supercooling is determined, and the opening degrees of the indoor expansion valves 82a and 82b are determined accordingly.

  The refrigerant that passes through the indoor expansion valves 82a and 82b, flows through the refrigerant pipes 87a and 87b, and flows out of the indoor units 8a and 8b flows into the liquid pipe 32. A part of the refrigerant flowing into the liquid pipe 32 flows into the branching device 72, and the rest flows through the liquid pipe 32 into the indoor units 8c and 8d. The refrigerant that has flowed into the branching device 72 is divided into the liquid distribution pipes 32a to 32c, and flows into the outdoor units 2a to 2c via the closing valves 42a to 42c.

  The refrigerant flowing into the outdoor units 2a to 2c is reduced in pressure when passing through the outdoor expansion valves 43a to 43c, becomes a low-pressure refrigerant, flows into the outdoor heat exchangers 23a to 23c, exchanges heat with the outside air, and evaporates. . The refrigerant flowing out of the outdoor heat exchangers 23a-23c passes through the four-way valves 22a-22c, flows into the refrigerant pipes 38a-38c, and flows into the outdoor unit low-pressure gas pipes 34a-34c from the connection points B, F, K. . The refrigerant that has flowed into the outdoor unit low-pressure gas pipes 34a to 34c flows through the refrigerant pipes 39a to 39c through the accumulators 25a to 25c, is sucked into the compressors 21a to 21c, and is compressed again.

  On the other hand, the intermediate-pressure refrigerant that flows out of the indoor units 8a and 8b, flows through the liquid pipe 32, and flows into the indoor units 8c and 8d passes through the indoor expansion valves 82c and 82d incorporated in the refrigerant pipes 87c and 87d, and is decompressed. Thus, the refrigerant becomes a low-pressure refrigerant and flows into the indoor heat exchangers 81c and 81d. The refrigerant that has flowed into the indoor heat exchangers 81c and 81d evaporates by exchanging heat with the indoor air. Thereby, cooling of the room in which the indoor units 8c and 8d are installed is performed. Note that the CPUs 810c and 810d of the indoor units 8c and 8d use the indoor heat exchangers 81c and 81d, which are evaporators, based on the refrigerant temperature detected by the refrigerant temperature sensors 84c and 84d and the refrigerant temperature detected by the refrigerant temperature sensors 85c and 85d. The degree of refrigerant superheat is obtained, and the opening degree of the indoor expansion valves 82c and 82d is determined accordingly.

  The refrigerant that has flowed out of the indoor heat exchangers 81c and 81d flows through the refrigerant pipes 88c and 88d, flows into the switching units 6c and 6d, and is opened via the connection points Tc and Td. It flows through the second branch pipes 92c and 92d provided with 62d. Then, it flows out from the switching units 6 c and 6 d and flows into the low pressure gas pipe 31. At this time, the refrigerant amount flowing into the fifth branch pipes 95c and 95d from the connection points Tc and Td and flowing into the fourth branch pipes 94c and 94d through the connection points Rc and Rd is supplied to the fifth branch pipes 95c and 95d. Since one capillary tube 65c, 65d is incorporated, it becomes very small. Further, since the refrigerant pressure at the connection points Pc and Pd is higher than the refrigerant pressure at the connection points Rc and Rd, the refrigerant does not flow from the connection points Rc and Rd to the bypass pipes 96c and 96d.

  The refrigerant that has flowed into the low-pressure gas pipe 31 flows into the branching device 71, and is branched from the branching device 71 to the low-pressure gas distribution pipes 31a to 31c. The refrigerant flowing through the low pressure gas distribution pipes 31a to 31c and flowing into the outdoor units 2a to 2c passes through the refrigerant pipes 39a to 39c from the outdoor unit low pressure gas pipes 34a to 34c via the connection points B, F, K and the accumulators 25a to 25c. The flow is sucked into the compressors 21a to 21c and compressed again.

  Next, pressure equalization processing control in the air-conditioning apparatus 1 of the present embodiment will be described with reference to FIGS. 1 to 5. The switching unit operation table 200 shown in FIG. 3 is stored in advance in the storage units 820a to 820d of the control units 800a to 800d of the indoor units 8a to 8d. This switching unit operation table 200 defines the open / close states of the valves of the switching units 6a to 6d corresponding to the indoor units 8a to 8d according to the states of the indoor units 8a to 8d.

  The item of the state of the indoor unit is divided into a case where the indoor units 8a to 8d are performing a heating operation and a case where a cooling operation is being performed. In the heating operation, the normal heating operation is performed during normal time, and the switching from the cooling operation to the heating operation is performed during pressure increase. In the cooling operation, the normal cooling operation is set as normal time, and the switching from the heating operation to the cooling operation is set as the step-down time.

  In the switching unit operation table 200, the first opening / closing means 61a to 61d and the third opening / closing means 63a to 63d are opened, and the second opening / closing means 62a to 62d and the fourth opening / closing means 64a to 64d are closed during the normal heating operation. Yes. At the time of boosting, only the third opening / closing means 63a to 63d are opened, and the first opening / closing means 61a to 61d, the second opening / closing means 62a to 62d, and the fourth opening / closing means 64a to 64d are closed.

  In the normal operation in the cooling operation, the second opening / closing means 62a to 62d and the fourth opening / closing means 64a to 64d are opened, and the first opening / closing means 61a to 61d and the third opening / closing means 63a to 63d are closed. At the time of step-down, only the fourth opening / closing means 64a to 64d are opened, and the first opening / closing means 61a to 61d, the second opening / closing means 62a to 62d, and the third opening / closing means 63a to 63d are closed.

  Next, control of each valve of the switching units 6a to 6d using the switching unit operation table 200 will be described. In an indoor unit that is performing a heating operation, such as the indoor units 8a and 8b illustrated in FIG. 1, the CPUs 810a and 810b refer to the normal items of the heating operation in the switching unit operation table 200, and the first opening / closing means 61a. 61b and the third opening / closing means 63a, 63b are opened, so that the refrigerant flowing into the switching units 6a, 6b from the high-pressure gas pipe 30 is transferred to the indoor heat exchangers 81a, 81b of the indoor units 8a, 8b as described above. The indoor heat exchangers 81a and 81b are caused to function as condensers.

  Further, in the indoor units that are performing the cooling operation, such as the indoor units 8c and 8d illustrated in FIG. 1, the CPUs 810c and 810d refer to the items in the normal cooling operation of the switching unit operation table 200 and perform the second opening / closing. By opening the means 62c, 62d and the fourth opening / closing means 64c, 64d, as described above, the refrigerant flows from the liquid pipe 32 to the indoor heat exchangers 81c, 81d of the indoor units 8c, 8d, so that the indoor heat exchanger 81c , 81d function as an evaporator.

  In the indoor units 8a to 8d, when switching from the heating operation to the cooling operation, or when switching from the cooling operation to the heating operation (hereinafter, described as switching the operation mode except when necessary), the control units 800a to 800a The 800d CPUs 810a to 810d refer to the switching unit operation table 200 to control the valves of the switching units 6a to 6d, and perform pressure equalization processing control as described below.

  For example, when switching the indoor unit 8a performing the heating operation to the cooling operation, the CPU 810a fully closes the indoor expansion valve 82a and stops the operation of the indoor unit 8a. Further, the CPU 810a refers to the item at the time of step-down of the cooling operation of the switching unit operation table 200, closes the first opening / closing means 61a, the second opening / closing means 62a and the third opening / closing means 63a, and opens only the fourth opening / closing means 64a. And

  The reason why only the fourth opening / closing means 64a is opened when the indoor unit 8a is switched from the heating operation to the cooling operation is as follows. When the indoor unit 8a is performing the heating operation, the refrigerant pressure on the indoor unit 8a side (connection point Ta side) of the closed second opening / closing means 62a, that is, the refrigerant pressure in the indoor heat exchanger 81a is the second. It is higher than the refrigerant pressure on the low-pressure gas pipe 31 side (connection point Sa side) of the opening / closing means 62a. In this state, when the second opening / closing means 62a is opened in order to perform the cooling operation, the refrigerant vigorously flows through the second opening / closing means 62a due to the pressure difference between both ends of the second opening / closing means 62a, and noise due to this is generated. There is a fear.

  Therefore, when switching the indoor unit 8a from the heating operation to the cooling operation, the opened first opening / closing means 61a and the third opening / closing means 63a are closed and the fourth opening / closing means 64a is opened. By opening the fourth opening / closing means 64a, the connection point Sa and the connection point Ta communicate with each other through the fourth branch pipe 94a and the fifth branch pipe 95a, and the refrigerant pressure at the connection point Ta is changed to the first capillary tube. Gradually descends (decreases pressure) by 65a.

  The CPU 810a continues the state in which only the fourth opening / closing means 64a is opened for a predetermined time (for example, 10 minutes), and sets the pressure difference between both ends of the second opening / closing means 62a to a predetermined value (for example, 0.3 MPa) or less. . The predetermined value of the pressure difference is a pressure difference that has been obtained in advance by a test or the like and that has confirmed that the refrigerant does not flow rapidly. The predetermined time is obtained in advance by a test or the like and stored in the storage unit 820a. When only the fourth opening / closing means 64a is opened, the pressure difference between both ends of the second opening / closing means 62a is This is the time required to become a predetermined value or less.

  When the predetermined time has elapsed, the CPU 810a opens the second opening / closing means 62a and opens the indoor expansion valve 82a at an opening degree corresponding to the required driving ability. As described above, when the opening / closing control of the fourth opening / closing means 64a and the second opening / closing means 62a of the switching unit 6a is performed, when the second opening / closing means 62a is opened, the pressure difference between both ends of the second opening / closing means 62a is less than a predetermined value. Therefore, even if the second opening / closing means 62a is opened, the refrigerant does not flow rapidly, and the generation of noise due to the refrigerant flowing through the second opening / closing means 62a can be reduced. The pressure equalization process control when switching the indoor unit from the heating operation to the cooling operation will be referred to as a pressure reduction process control in the following description.

  For example, when switching the indoor unit 8c that is performing the cooling operation to the heating operation, the CPU 810c fully closes the indoor expansion valve 82c and stops the operation of the indoor unit 8c. Further, the CPU 810c refers to the item at the time of boosting the heating operation of the switching unit operation table 200, closes the first opening / closing means 61a, the second opening / closing means 62a, and the fourth opening / closing means 64a, and opens only the third opening / closing means 63a. And

  When the indoor unit 8c is performing a cooling operation, the refrigerant pressure on the indoor unit 8c side (connection point Tc side) of the closed first opening / closing means 61c, that is, the refrigerant pressure in the indoor heat exchanger 81c is the first. It is lower than the refrigerant pressure on the high-pressure gas pipe 30 side (connection point Qc side) of the opening / closing means 61c. In this state, when the first opening / closing means 61c is opened to perform the heating operation, the refrigerant vigorously flows through the first opening / closing means 61c due to the pressure difference between the both ends of the first opening / closing means 61c, and noise resulting therefrom is generated. There is a fear.

  Therefore, when the indoor unit 8c is switched from the cooling operation to the heating operation, the opened second opening / closing means 62c and the fourth opening / closing means 64c are closed and the third opening / closing means 63c is opened. By opening the third opening / closing means 63c, the connection point Qc and the connection point Tc communicate with each other through the third branch pipe 93c and the fifth branch pipe 95c, so that the refrigerant pressure at the connection point Tb is changed to the first capillary. The tube 65c gradually increases (pressure-increase).

  The CPU 810c continues the state in which only the third opening / closing means 63c is opened for a predetermined time (for example, 10 minutes), and sets the pressure difference between both ends of the first opening / closing means 61c to a predetermined value (for example, 0.3 MPa) or less. . The predetermined value of the pressure difference is determined in the same manner as when the indoor unit 8a is switched from the heating operation to the cooling operation. The predetermined time is obtained in advance by a test or the like and stored in the storage unit 820c. When only the third opening / closing means 63c is opened, the pressure difference between both ends of the first opening / closing means 61c is reduced. This is the time required to become a predetermined value or less.

  When the predetermined time elapses, the CPU 810c opens the first opening / closing means 61c and opens the indoor expansion valve 82c at an opening corresponding to the required driving ability. As described above, when the opening / closing control of the third opening / closing means 63c and the first opening / closing means 61c of the switching unit 6c is performed, the pressure difference between both ends of the first opening / closing means 61c is less than a predetermined value when the first opening / closing means 61c is opened. Therefore, even if the first opening / closing means 61c is opened, the refrigerant does not flow rapidly, and the generation of noise due to the refrigerant flowing through the first opening / closing means 61c can be reduced. In the following description, the pressure equalization process control when the indoor unit is switched from the cooling operation to the heating operation is referred to as a pressure increase process control.

  As described above, in the indoor units 8a to 8d, when the operation mode is switched, the first opening / closing means 61a to 61d and the like are performed by performing the pressure increasing process control and the pressure decreasing process control in the corresponding switching units 6a to 6d. It is possible to switch the operation mode of the indoor units 8a to 8d by reducing the generation of noise due to the pressure difference between both ends of the second opening / closing means 62a to 62d. However, as described above, when switching the operation mode, it is necessary to perform the pressure increasing process control and the pressure decreasing process control for a predetermined time, and during this period, the indoor units 8a to 8d that switch the operation mode are stopped.

  On the other hand, in addition to the heating / heating main operation and the cooling / cooling main operation described above, the air conditioner 1 performs a defrosting operation for removing frost generated in the outdoor heat exchangers 23a to 23c, and the compressors 21a to 21a. An operation such as an oil recovery operation for recovering refrigeration oil discharged together with the refrigerant from 21c to the compressors 21a to 21c can be performed.

  As one of the methods for performing the defrosting operation and the oil recovery operation, in the refrigeration cycle of the air conditioner 1, the outdoor heat exchangers 23a to 23c function as a condenser and the indoor heat exchangers 81a to 81a of the indoor units 8a to 8d. There are a reverse defrosting operation and a reverse oil recovery operation which are performed by causing all 81d to function as an evaporator. When the air conditioner 1 is performing the heating operation or the heating-main operation, the operation moves to the reverse defrosting operation or the reverse oil recovery operation, and after the reverse defrosting operation or the reverse oil recovery operation is finished, the heating operation or the heating main operation is performed. When the outdoor heat exchangers 23a to 23c function as evaporators, the indoor units 8a to 8d operate the indoor heat exchangers 81a to 81d as evaporators or condensers according to the operation mode. It is necessary to switch the refrigeration cycle of the harmony device 1.

  When switching from the state in which the outdoor heat exchangers 23a to 23c function as a condenser to the state in which the outdoor heat exchangers 23a to 23c function as an evaporator, the CPUs 110a to 110c stop the compressors 21a to 21c, switch the four-way valves 22a to 22c, and bypass The electromagnetic valves 44a to 44c are opened so that the refrigerant flows through the hot gas bypass pipes 36a to 36c.

  As shown in FIG. 1, the outdoor unit high-pressure gas pipes 33a to 33c and the outdoor unit low-pressure gas pipes 34a to 34c are bypassed by the hot gas bypass pipes 36a to 36c by flowing the refrigerant through the hot gas bypass pipes 36a to 36c. Therefore, the refrigerant pressure in the high pressure gas pipe 30 and the refrigerant pressure in the low pressure gas pipe 31 are equalized. Therefore, the compressors 21a to 21c are stopped as in the case of switching from the reverse defrosting operation or the reverse oil recovery operation to the heating operation or the heating main operation in this embodiment, compared to the case of switching the operation mode with one indoor unit. When the refrigerant circuit is switched, there is an opportunity to equalize the refrigerant pressure in the high pressure gas pipe 30 and the refrigerant pressure in the low pressure gas pipe 31 so that the refrigerant can flow through the hot gas bypass pipes 36a to 36c. Can shorten the time for performing pressure equalization processing control in the indoor units 8a to 8d.

  Hereinafter, the pressure equalization process control when switching from the reverse defrosting operation or the reverse oil recovery operation to the heating operation or the heating main operation will be specifically described. In the following description, when the air-conditioning apparatus 1 performs the heating main operation shown in FIG. 1, the condition for starting the defrosting operation is established in the outdoor unit 2a, and the reverse defrosting operation is performed. The case of returning to the heating-main operation of 1 will be described as an example.

  When the air-conditioning apparatus 1 performs the heating-main operation shown in FIG. 1, when the defrosting operation start condition is established in the outdoor unit 2a, the CPU 110a transmits the other outdoor units 2b and 2c and the indoors via the communication unit 130a. The defrosting operation preparation signal is transmitted to the machines 8a to 8d, and the control for performing the reverse defrosting operation is started. Here, the defrosting operation start condition is a condition that frost formation is considered to have occurred in the outdoor heat exchanger 23a. For example, a state where the outside air temperature detected by the outside air temperature sensor 57a is 0 ° C. or less. This is the case when it continues for 30 minutes or more, or when the refrigerant temperature detected by the heat exchanger temperature sensor 56a is −5 ° C. or lower. The CPU 110a periodically takes in the outside air temperature detected by the outside air temperature sensor 57a and the refrigerant temperature detected by the heat exchange temperature sensor 56a, and determines whether the defrosting operation start condition is satisfied or not.

  When the defrosting operation start condition is satisfied, the CPU 110a performs a defrosting operation preparation process for switching the refrigerant circuit of the outdoor unit 2a so that the reverse defrosting operation can be performed. Specifically, the CPU 110a stops the compressor 21a and opens the bypass electromagnetic valve 44a so that the refrigerant flows through the hot gas bypass pipe 36a. In addition, the outdoor heat exchanger 23a functions as a condenser by switching the four-way valve 22a so that the port a and the port b communicate with each other and the port c and the port d communicate with each other. The CPU 110a of the outdoor unit 2a measures the time after the start of the defrosting operation preparation process, and waits until a predetermined time (for example, 3 minutes) elapses after the start of the defrosting operation preparation process. During the predetermined time, the pressures in the indoor heat exchangers 81a and 81b of the indoor units 8a and 8b that have been performing the heating operation so that the refrigerant flows through the hot gas bypass pipes 36a to 36c in the outdoor units 2a to 2c are predetermined values. This is the time required until the following, which is obtained in advance by a test or the like and stored in the storage unit 120a.

  Moreover, CPU110b which received the defrost operation preparation signal via the communication part 130b performs the defrost operation preparation process of the outdoor unit 2b. Specifically, the CPU 110b stops the compressor 21b and opens the bypass solenoid valve 44b so that the refrigerant flows through the hot gas bypass pipe 36b. Further, the four-way valve 22b is switched so that the port e and the port f communicate with each other and the port g and the port h communicate with each other so that the outdoor heat exchanger 23b functions as a condenser. Similarly, CPU110c which received the defrosting operation preparation signal via the communication part 130c performs the defrosting operation preparation process of the outdoor unit 2c. In the defrosting operation start process, the CPU 110c stops the compressor 21c and opens the bypass solenoid valve 44c so that the refrigerant flows through the hot gas bypass pipe 36c. Further, the four-way valve 22c is switched so that the port j and the port k communicate with each other and the port m and the port n communicate with each other so that the outdoor heat exchanger 23c functions as a condenser. CPU110b, 110c which performed the defrosting operation preparation process of the outdoor units 2b and 2c waits for the instruction | indication from CPU110a of the outdoor unit 2a.

  On the other hand, if CPU 810a-810d receives a defrost operation preparation signal via communication part 830a-d, it will perform the defrost operation preparation process of indoor unit 8a-8d. In the defrosting operation preparation process, the CPUs 810a to 810d fully close the indoor expansion valves 82a to 82d. Further, the first opening / closing means 61a to 61d and the third opening / closing means 63a to 63d of the switching units 6a to 6d corresponding thereto are closed, and the refrigerant flows through the first branch pipes 91a to 91d and the third branch pipes 93a to 93d. In addition, the second opening / closing means 62a to 62d and the fourth opening / closing means 64a to 64d are opened so that the refrigerant flows through the second branch pipes 92a to 92d and the fourth branch pipes 94a to 94d. The indoor heat exchangers 81a to 81d of the indoor units 8a to 8d function as evaporators by opening / closing control of the valves of the switching units 6a to 6d. The CPUs 810a to 810d that have performed the defrosting operation preparation processing of the indoor units 8a to 8d wait for an instruction from the CPU 110a of the outdoor unit 2a.

  When the predetermined time has elapsed, the CPU 110a transmits a defrosting operation start signal to the other outdoor units 2b and 2c and the indoor units 8a to 8d via the communication unit 130a. Then, the CPU 110a closes the bypass valve 44a and drives the compressor 21a at a predetermined rotation speed (for example, 80 rps) to start the reverse defrosting operation. Further, the CPUs 110b and 110c that have received the defrosting operation start signal via the communication units 130b and 130c also close the bypass valves 44b and 44c and drive the compressors 21b and 21c at a predetermined rotational speed, similarly to the CPU 110a. Start reverse defrosting operation. In addition, when performing reverse defrost operation, outdoor fan 24a-24c has stopped.

  Moreover, if CPU810a-810d receives a defrost operation start signal via communication part 830a-d, it will make indoor expansion valve 82a-82d predetermined opening. Thereby, the refrigerant circuit at the time of reverse defrost operation shown in FIG. 4 is formed. Note that the indoor fans 83a to 83d are stopped when the reverse defrosting operation is performed.

  The high-temperature and high-pressure refrigerant discharged from the compressors 21a to 21c flows through the outdoor unit high-pressure gas pipes 33a to 33c, flows from the four-way valves 22a to 22c to the refrigerant pipes 37a to 37c, and flows into the outdoor heat exchangers 23a to 23c. . The refrigerant flowing into the outdoor heat exchangers 23a to 23c melts and condenses the frost generated in the outdoor heat exchangers 23a to 23c. The refrigerant that has flowed out of the outdoor heat exchangers 23a to 23c is reduced in pressure when passing through the outdoor expansion valves 43a to 43c, becomes an intermediate pressure refrigerant, and is liquidated from the outdoor unit liquid pipes 35a to 35c through the closing valves 42a to 42c. It flows into the branch pipes 32 a to 32 c and joins at the branching device 72.

  The refrigerant flowing into the liquid pipe 32 from the branching device 72 flows into the indoor units 8a to 8d, passes through the indoor expansion valves 82a to 82d having a predetermined opening degree, is reduced in pressure, and becomes a low-pressure refrigerant. It flows into 81a-81d. The refrigerant flowing into the indoor heat exchangers 81a to 81d evaporates and flows out of the indoor heat exchangers 81a to 81d, flows through the refrigerant pipes 88a to 88d, and flows into the switching units 6a to 6d.

  The refrigerant that has flowed into the switching units 6a to 6d flows through the second branch pipes 92a to 92d in which the opened second opening / closing means 62a to 62d are incorporated via the connection points Ta to Td. Then, the refrigerant flowing out of the switching units 6a to 6d and flowing into the low pressure gas pipe 31 flows into the branching device 71, and is branched from the branching device 71 into the low pressure gas distribution tubes 31a to 31c. The refrigerant flowing through the low pressure gas distribution pipes 31a to 31c and flowing into the outdoor units 2a to 2c passes through the refrigerant pipes 39a to 39c from the outdoor unit low pressure gas pipes 34a to 34c via the connection points B, F, K and the accumulators 25a to 25c. The flow is sucked into the compressors 21a to 21c and compressed again.

  When the defrosting operation end condition is satisfied in all the outdoor units 2a to 2c during the reverse defrosting operation described above, the CPU 110a causes the other outdoor units 2b and 2c and the indoor units to be connected via the communication unit 130a. The defrosting operation end signal is transmitted to 8a to 8d, and the control for ending the reverse defrosting operation and returning to the heating main operation is started. Here, the defrosting operation end condition is a condition that the defrosting in the outdoor heat exchangers 23a to 23c is considered to have ended. For example, a predetermined time (for example, 15 minutes) after the start of the reverse defrosting operation. This is the case when it has elapsed, or when the refrigerant temperature detected by each of the refrigerant temperature sensors 55a to 55c is 5 ° C. or higher. In addition, if the defrosting operation completion conditions are satisfied in the outdoor units 2b and 2c, the CPU 110b and the CPU 110c transmit a signal including the fact (end condition establishment signal) to the outdoor unit 2a via the communication units 130b and 130c. The CPU 110a that has received this signal via the communication unit 130a recognizes that the defrosting operation termination condition has been established in the outdoor units 2b and 2c.

  As shown in FIG. 5, the CPU 110a performs a defrosting operation end process for the outdoor unit 2a when the defrosting operation end condition is satisfied. In the defrosting operation end process, the CPU 110a stops the compressor 21a and opens the bypass electromagnetic valve 44a so that the refrigerant flows through the hot gas bypass pipe 36a. Further, the four-way valve 22a is switched so that the port a and the port d communicate with each other and the port b and the port c communicate with each other, so that the outdoor heat exchanger 23a functions as an evaporator. Then, the CPU 110a takes in the refrigerant discharge pressure detected by the high-pressure sensor 50a and the refrigerant suction pressure detected by the low-pressure sensor 51a, and calculates the pressure difference between them. When this pressure difference is higher than a predetermined value (for example, 0.3 MPa), the CPU 110a transmits a pressure equalization process execution signal to the indoor units 8a to 8d. Then, after transmitting the pressure equalization processing execution signal, the CPU 110a waits until the pressure difference between the discharge pressure and the suction pressure taken in periodically becomes a predetermined value or less.

  Moreover, CPU110b which received the defrosting operation completion signal via the communication part 130b performs the defrosting operation completion process of the outdoor unit 2b. In the defrosting operation end process, the CPU 110b stops the compressor 21b and opens the bypass electromagnetic valve 44b so that the refrigerant flows through the hot gas bypass pipe 36b. Further, the four-way valve 22b is switched so that the port e and the port h communicate with each other and the port f and the port g communicate with each other so that the outdoor heat exchanger 23b functions as a condenser. Similarly, CPU110c which received the defrost operation preparation signal via the communication part 130c performs the defrost operation completion | finish process of the outdoor unit 2c. In the defrosting operation end process, the CPU 110c stops the compressor 21c and opens the bypass electromagnetic valve 44c so that the refrigerant flows through the hot gas bypass pipe 36c. Further, the four-way valve 22c is switched so that the port j and the port n communicate with each other and the port k and the port m communicate with each other so that the outdoor heat exchanger 23c functions as a condenser. CPU110b, 110c which performed the defrost operation completion | finish process of outdoor unit 2b, 2c waits for the instruction | indication from CPU110a of the outdoor unit 2a.

  When the pressure difference between the discharge pressure and the suction pressure is equal to or less than a predetermined value, the CPU 110a transmits an operation restart signal to the other outdoor units 2b and 2c and the indoor units 8a to 8d via the communication unit 130a, and bypass electromagnetic The valve 44a is closed and the compressor 21a is started at a rotational speed corresponding to the required operating load. Similarly to the CPU 110a, the CPUs 110b and 110c that have received the operation resumption signal via the communication units 130b and 130c close the bypass solenoid valves 44b and 44c and respond to the operation load required for the compressors 21b and 21c. Start at the number of revolutions.

  On the other hand, as shown in FIG. 5, the CPUs 810 a to 810 d fully close the indoor expansion valves 82 a to 82 d when receiving the defrosting operation end signal via the communication units 830 a to 830 d. In this state, when a pressure equalization processing execution signal is received from the outdoor unit 2a, the CPUs 810a and 810b of the indoor units 8a and 8b that resume operation in the heating operation refer to the switching unit operation table 200 and correspond to each. The first opening / closing means 61a, 61b, the second opening / closing means 62a, 62b and the fourth opening / closing means 64a, 64b of the switching unit 6a, 6b are closed, and the first branch pipes 91a, 91b and the second branch pipes 92a, 92b While the refrigerant does not flow through the fourth branch pipes 94a and 94b, the pressure increasing process control is executed so that the third opening / closing means 63a and 63b are opened and the refrigerant flows only through the third branch pipes 93a and 93b.

Further, the CPUs 810c and 810d of the indoor units 8c and 8d that restart the operation by the cooling operation refer to the switching unit operation table 200, and the first opening and closing means 61c and 61d and the second opening and closing of the switching units 6c and 6d corresponding to each of them. The means 62c, 62d and the third opening / closing means 63c, 63d are closed so that the refrigerant does not flow through the first branch pipes 91a, 91b, the second branch pipes 92a, 92b, and the third branch pipes 93a, 93b. Then, the fourth opening / closing means 64c, 64d is opened, and the pressure reduction processing control is performed so that the refrigerant flows only in the fourth branch pipes 94c, 94d.
The CPUs 810a to 810d that have executed the step-up process control and the step-down process control stand by until an operation restart signal is transmitted from the outdoor unit 2a.

  Then, if the CPUs 810a to 810d receive the operation restart signal via the communication units 830a to 830d, the indoor expansion valves 82a to 82d are set in accordance with the refrigerant superheat degree and the refrigerant subcool degree in the indoor heat exchangers 81a to 81d. And opening / closing control of each valve of the switching units 6a to 6d according to the indoor units 8a and 8b that perform the heating operation and the indoor units 8c and 8d that perform the cooling operation with reference to the switching unit operation table 200. This is the refrigerant circuit during the heating main operation described with reference to FIG.

  As described above, when switching from the reverse defrosting operation to the heating main operation, the pressure difference between the discharge pressure and the suction pressure is calculated, and if the pressure difference is equal to or less than a predetermined value, the pressure equalization processing control is terminated. It is possible to shorten the time for performing the pressure increasing process control in the switching unit corresponding to the indoor unit performing the heating operation and the pressure decreasing process control in the switching unit corresponding to the indoor unit performing the cooling operation.

  In the embodiment described above, frost formation occurs in the outdoor heat exchanger 23a of the outdoor unit 2a, and the CPU 110a of the indoor unit 2a instructs other devices regarding switching to reverse defrosting operation and pressure equalization processing control. However, when frost formation is detected in another outdoor unit, the CPU of the outdoor unit gives instructions to other devices regarding switching to reverse defrosting operation and pressure equalization processing control. Further, the case where the reverse defrosting operation is performed has been described as an example, but the refrigerant circuit in the case of performing the reverse oil recovery operation is the same as the refrigerant circuit in the case of performing the reverse defrosting operation. The pressure equalization control when switching to the heating main operation can be performed in the same manner as when switching from the reverse defrosting operation to the heating main operation.

  Moreover, although the case where the 1st capillary tube 65a-65d was integrated in the 5th branch pipe 95a-95b as what comprises the pressure equalization means with which switching unit 6a-6d was comprised was demonstrated, the 1st capillary tube 65a The third opening / closing means 63a-63d and the fourth opening / closing means 64a-64d can reduce the amount of refrigerant that can be passed as compared to the first opening / closing means 61a-61d and the second opening / closing means 62a-62d. May be selected and incorporated into the third branch pipes 93a to 93d and the fourth branch pipes 94a to 94d.

  Next, the flow of processing in the air conditioner 1 in the present embodiment will be described using the flowcharts shown in FIGS. 6 and 7. The flowchart shown in FIG. 6 shows the flow of processing in the control units 100a to 100c of the outdoor units 2a to 2c related to pressure equalization processing control, and (A) is in the CPU of the outdoor unit that satisfies the defrosting operation start condition. The flow of the process at the time of performing a reverse defrost operation, (B) is the process at the time of performing the reverse defrost operation in CPU of the outdoor unit which performs control by the instruction | indication from the outdoor unit in which the defrost operation start conditions were satisfied Is shown. Moreover, the flowchart shown in FIG. 7 shows the flow of processing in the control units 800a to 800d of the indoor units 8a to 8d related to pressure equalization processing control. In any flowchart, ST represents a step, and the number following this represents a step number.

  6 and 7 mainly describe the processes related to the present invention. For example, the processes related to the air conditioning operation such as the control of the refrigerant circuit corresponding to the operating conditions such as the set temperature and the air volume instructed by the user are described. Description of the general processing flow is omitted. Moreover, in the following description, when the air-conditioning apparatus 1 is performing the heating main operation as in the embodiment, the defrosting operation start condition is established in the outdoor unit 2a, and the reverse defrosting operation is performed. The flow of processing will be described by taking as an example the case of returning to the heating-main operation after the operation is completed.

  First, the processing in the CPU 110a of the control unit 100a in the outdoor unit 2a in which the defrosting operation start condition is satisfied will be described with reference to FIG. When the air conditioner 1 is performing the heating main operation, the CPU 110a determines whether or not the defrosting operation start condition is satisfied (ST1). If the defrosting operation start condition is not satisfied (ST1-No), the CPU 110a continues the current heating main operation (ST14), and returns the process to ST1.

  If the defrosting operation start condition is satisfied (ST1-Yes), the CPU 110a transmits a defrosting operation preparation signal to the other outdoor units 2b and 2c and the indoor units 8a to 8d (ST2). Next, the CPU 110a executes a defrosting operation preparation process for the outdoor unit 2a (ST3).

  Next, the CPU 110a starts timer measurement (ST4). Then, the CPU 110a determines whether or not a predetermined time has elapsed (ST5). If the predetermined time has not elapsed (ST5-No), the process returns to ST5, and if the predetermined time has elapsed (ST5-). Yes), the process proceeds to ST6.

  In ST6, the CPU 110a transmits a defrosting operation start signal to the other outdoor units 2b and 2c and the indoor units 8a to 8d. Next, the CPU 110a closes the bypass solenoid valve 44a and activates the compressor 21a to start the reverse defrosting operation (ST7).

  Next, the CPU 110a determines whether or not the defrosting operation end condition is satisfied in all the outdoor units 2a to 2c (ST8). If the defrosting operation end condition is not satisfied (ST8-No), the CPU 110a returns the process to ST7 and continues the reverse defrosting operation. If the defrosting operation end condition is satisfied (ST8-Yes), the CPU 110a transmits a defrosting operation end signal to the other outdoor units 2b and 2c and the indoor units 8a to 8d (ST9). Then, the CPU 110a performs a defrosting operation end process (ST10).

  Next, the CPU 110a determines whether or not the pressure difference between the discharge pressure detected by the high pressure sensor 50 and the suction pressure detected by the low pressure sensor 51 is equal to or less than a predetermined value (ST11). If the pressure difference is not less than or equal to the predetermined value (ST11-No), the CPU 110a transmits a pressure equalization process execution signal to the indoor units 8a to 8d (ST15), and returns the process to ST11.

  If the pressure difference is equal to or less than the predetermined value (ST11-Yes), the CPU 110a transmits an operation resumption signal to the other outdoor units 2b, 2c and the indoor units 8a-8d (ST12). Then, the CPU 110a closes the bypass solenoid valve 44a and activates the compressor 21a to restart the heating main operation (ST13), and returns the process to ST1.

  Next, referring to FIG. 6B, the CPUs 110b of the control units 100b and 100c in the outdoor units 2b and 2c that perform the reverse defrosting operation in response to an instruction from the outdoor unit 2a that satisfies the defrosting operation start condition, The processing at 110c will be described. When the air conditioner 1 performs the heating main operation, the CPUs 110b and 110c determine whether or not a defrosting operation preparation signal has been received from the outdoor unit 2a (ST41). If the defrosting operation preparation signal has not been received (ST41-No), the CPUs 110b and 110c continue the heating-main operation currently being performed (ST51) and return the process to ST41.

  If the defrosting operation preparation signal is received (ST41-Yes), CPU110b, 110c will perform the defrosting operation preparation process of each outdoor unit 2b, 2c (ST42).

  Next, CPU110b, 110c judges whether the defrost operation start signal was received from the outdoor unit 2a (ST43). If the defrosting operation start signal has not been received (ST43-No), the CPUs 110b and 110c return the process to ST43.

  If the defrosting operation start signal has been received (ST43-Yes), the CPUs 110b and 110c close the bypass solenoid valves 44b and 44c, respectively, start the compressors 21b and 21c, respectively, and start the reverse defrosting operation ( ST44).

  Next, the CPUs 110b and 110c determine whether or not the defrosting operation end condition is satisfied in the outdoor units 2b and 2c (ST45). If the defrosting operation termination condition is not satisfied (ST45-No), the CPUs 110b and 110c return the process to ST44 and continue the reverse defrosting operation. If the defrosting operation end condition is satisfied (ST45-Yes), the CPUs 110b and 110c transmit an end condition satisfaction signal to the outdoor unit 2a (ST46).

  Next, the CPUs 110b and 110c determine whether or not a defrosting operation end signal is received from the outdoor unit 2a (ST47). If the defrosting operation end signal has not been received (ST47-No), the CPUs 110b and 110c return the process to ST47. If the defrosting operation end signal is received (ST47-Yes), the CPUs 110b and 110c perform a defrosting operation end process (ST48).

  Next, the CPUs 110b and 110c determine whether or not an operation resumption signal is received from the outdoor unit 2a (ST49). If the operation restart signal has not been received (ST49-No), the CPUs 110b and 110c return the process to ST49. If the operation resumption signal has been received (ST49-Yes), the CPUs 110b and 110c close the bypass solenoid valves 44b and 44c, respectively, start the compressors 21b and 21c, respectively, and resume the heating main operation (ST50). , The process returns to ST41.

  Next, processing in the CPUs 810a to 810d of the control units 800a to 800d will be described with reference to FIG. When the indoor units 8a to 8d are performing the heating operation or the cooling operation, the CPUs 810a to 810d determine whether or not the defrosting operation preparation signals are received from the outdoor units 2a to 2c (ST21).

  If the defrosting operation preparation signal has not been received (ST21-No), the CPUs 810a to 810d continue the current heating operation and cooling operation (ST32), and return the processing to ST21. If the defrosting operation preparation signal is received (ST21-Yes), CPU810a-810d will perform the defrosting operation preparation process of indoor unit 8a-8d (ST22).

  Next, the CPUs 810a to 810d determine whether or not defrosting operation start signals have been received from the outdoor units 2a to 2c (ST23). If CPUs 810a to 810d have not received the defrosting operation start signal (ST23-No), the process returns to ST23, and if the defrosting operation start signal has been received (ST23-Yes), the process proceeds to ST24. .

  In ST24, the CPUs 810a to 810d refer to the switching unit operation table 200 and open and close the valves of the corresponding switching units 6a to 6d. Next, the CPUs 810a to 810d set the opening degree of the indoor expansion valves 82a to 82d to a predetermined opening degree (ST25).

  Next, CPUs 810a to 810d determine whether or not a defrosting operation end signal has been received from outdoor units 2a to 2c (ST26). If CPUs 810a to 810d have not received the defrosting operation end signal (ST26-No), the process returns to ST26, and if the defrosting operation end signal has been received (ST26-Yes), the process proceeds to ST27. .

  In ST27, the CPUs 810a to 810d fully close the indoor expansion valves 82a to 82d. Next, CPUs 810a to 810d determine whether or not pressure equalization processing execution signals have been received from outdoor units 2a to 2c (ST28).

  If the pressure equalization processing execution signal has been received (ST28-Yes), the CPUs 810a to 810d refer to the switching unit operation table 200 and perform the pressure increase processing control in the switching unit corresponding to the indoor unit that performs the heating operation. The switching unit corresponding to the indoor unit to be operated performs the pressure reduction processing control, that is, the pressure equalization processing control in the switching unit is performed (ST33). The CPUs 810a to 810d that have performed the pressure equalization process control return the process to ST28.

  In ST28, if a pressure equalization process execution signal has not been received (ST28-No), CPUs 810a to 810d determine whether or not an operation resumption signal has been received (ST29). CPUs 810a to 810d return the process to ST29 if no operation resumption signal has been received (ST29-No), and proceed to ST30 if an operation resumption signal has been received (ST29-Yes).

  In ST30, the CPUs 810a to 810d refer to the switching unit operation table 200 and open and close the valves of the corresponding switching units 6a to 6d. Then, the CPUs 810a to 810d set the opening degree of the indoor expansion valves 82a to 82d to the opening degree corresponding to the degree of refrigerant superheat and the degree of refrigerant subcooling required in the corresponding indoor heat exchangers 81a to 81d (ST31), and ST1. Return processing to.

  As described above, the air conditioner of the present invention does not perform pressure equalization processing if the pressure difference between the discharge pressure and the suction pressure is equal to or less than a predetermined value. If the pressure difference between the discharge pressure and the suction pressure is equal to or less than a predetermined value during the pressure equalization process, the pressure equalization process is stopped. Therefore, the time for performing the pressure equalization process can be shortened, and the return from the defrosting operation or the oil recovery operation to the air conditioning operation can be accelerated.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2a-2c Outdoor unit 6a-6d Switching unit 8a-8d Indoor unit 21a-21c Compressor 22a-22c Four way valve 23a-23c Outdoor heat exchanger 30 High pressure gas pipe 30a-30c High pressure gas branch pipe 31 Low pressure gas pipe 31a-31c Low pressure gas distribution pipe 32 Liquid pipe 32a-32c Liquid distribution pipe 33a-33c Outdoor unit high pressure gas pipe 34a-34c Outdoor unit low pressure gas pipe 35a-35c Outdoor unit liquid pipe 36a-36c Hot gas bypass pipe 37a-37c Refrigerant piping 43a ˜43c Outdoor expansion valve 44a˜44c Bypass solenoid valve 50a˜50c High pressure sensor 51a˜51c Low pressure sensor 52a˜52c Intermediate pressure sensor 55a˜55c Refrigerant temperature sensor 56a˜56c Heat exchanger temperature sensor 57a˜57c Outside air temperature sensor 61a˜61d First opening / closing means 62a-6 d Second opening / closing means 63a to 63d Third opening / closing means 64a to 64d Fourth opening / closing means 65a to 65d First capillary tubes 66a to 66d Second capillary tubes 81a to 81d Indoor heat exchangers 82a to 82d Indoor expansion valves 91a to 91d First 1 branch pipe 92a-92d 2nd branch pipe 93a-93d 3rd branch pipe 94a-94d 4th branch pipe 95a-95d 5th branch pipe 96a-96d bypass pipe 100a-100c Outdoor unit control means 110a-110c CPU
120a to 120c Storage unit 130a to 130c Communication unit 200 Switching unit operation table 800a to 800d Indoor unit control means 810a to 810d CPU
820a to 820d storage unit 830a to 830d communication unit

Claims (3)

A compressor, an outdoor heat exchanger, an outside air temperature detecting means for detecting the outside air temperature, a high pressure detecting means for detecting a discharge pressure of the refrigerant discharged from the compressor, and a suction of the refrigerant sucked into the compressor Low pressure detecting means for detecting pressure, at least one outdoor unit,
A plurality of indoor units having an indoor heat exchanger and an indoor unit decompression means;
A plurality of switching units provided corresponding to the plurality of indoor units and switching the flow direction of the refrigerant in the indoor heat exchanger,
The outdoor unit and the plurality of switching units are connected by a high-pressure gas pipe and a low-pressure gas pipe, the plurality of indoor units are connected by at least one of the outdoor units and a liquid pipe, and the corresponding plurality of indoor units In the air conditioner in which the plurality of switching units are connected by refrigerant piping,
The switching unit includes pressure equalizing means for performing pressure equalization processing for increasing or decreasing the refrigerant pressure in the indoor heat exchanger provided in the indoor unit according to an instruction of the corresponding indoor unit,
The discharge detected by the high-pressure detection means when switching from a state where the outdoor heat exchanger functions as a condenser to perform a defrosting operation or an oil recovery operation to a state where the outdoor heat exchanger functions as an evaporator If the pressure difference between the pressure and the suction pressure detected by the low pressure detecting means is less than or equal to a predetermined value, the pressure equalizing process by the pressure equalizing means is not performed. The outdoor unit includes an outdoor unit opening / closing means and a hot gas bypass pipe connected to a refrigerant pipe connected to a refrigerant discharge port of the compressor and a refrigerant pipe connected to a refrigerant suction port,
When switching from the state in which the outdoor heat exchanger functions as a condenser to perform the defrosting operation or the oil recovery operation to the state in which the outdoor heat exchanger functions as an evaporator, open the outdoor unit opening / closing means to When the refrigerant flows through the gas bypass pipe and the outdoor unit opening / closing means is opened, the pressure difference between the discharge pressure detected by the high pressure detection means and the suction pressure detected by the low pressure detection means becomes less than a predetermined value. The air conditioning apparatus according to claim 1, wherein the pressure equalization process by the pressure equalizing unit is stopped. The switching unit includes a first branch pipe having a first opening / closing means and one end connected to the high-pressure gas pipe; and a second branch pipe having a second opening / closing means and one end connected to the low-pressure gas pipe; With
The pressure equalizing means includes a third shunt pipe having a third opening / closing means and one end connected to the first shunt pipe, and a fourth shunt having a fourth opening / closing means and one end connected to the second shunt pipe. It is composed of a shunt pipe and a fifth shunt pipe having flow rate limiting means,
The other end of the first shunt pipe and the other end of the second shunt pipe are connected and connected to the indoor unit by a refrigerant pipe, and the other end of the third shunt pipe and the other end of the fourth shunt pipe And one end of the fifth shunt pipe is connected to a connection portion between the first shunt pipe and the second shunt pipe, and the other end of the fifth shunt pipe is connected to the other end of the third shunt pipe. Connected to the connection with the fourth shunt pipe,
When switching from a state where the outdoor heat exchanger functions as a condenser to perform a defrosting operation or an oil recovery operation to a state where the outdoor heat exchanger functions as an evaporator, the pressure difference is less than a predetermined value. If present, the switching unit corresponding to the indoor unit that causes the indoor heat exchanger to function as a condenser corresponds to the indoor unit that opens at least the first opening / closing means and causes the indoor heat exchanger to function as an evaporator. The air conditioner according to claim 1 or 2, wherein at least the second opening / closing means is opened in the switching unit.

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