JP2009210139A - Multiple-type air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multiple-type air conditioner reducing switching noise without degrading an air-conditioning performance of an indoor unit in which cooling and heating are not switched. <P>SOLUTION: Switching of any of indoor units performing a cooling operation to a heating operation is performed through: a step of opening a closed second high-low pressure bypass opening/closing valve 64 after a command for switching the operation is given; a step of switching a connecting state of a port 48-1 for a high pressure gas pipe and a port 48-4 for a low pressure bypass pipe of an indoor four-way valve 48 from the state for cooling operation to the state for heating operation after the second high-low pressure bypass opening/closing valve 64 is opened; and a step of closing the second high-low pressure bypass opening/closing valve 64 after the connecting state of the port 48-1 for the high pressure gas pipe and the port 48-4 for the low pressure bypass pipe is switched from the state for cooling operation to the state for heating operation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multi-type air conditioner.

  There is known a multi-type air conditioner in which a plurality of indoor unit units are connected in parallel to one outdoor unit. In this air conditioner, a high-pressure gas pipe, a low-pressure gas pipe, and a liquid line are disposed between the outdoor unit and the indoor unit, and the high-pressure gas is disposed on the gas pipe side of each of the outdoor heat exchanger and each indoor heat exchanger. It is possible to switch between the pipe and the low-pressure gas pipe so as to selectively communicate with each other. During the operation of this air conditioner, a connection switching mechanism is provided for individually switching the connection with the gas pipe of each heat exchanger to the high pressure gas pipe and the low pressure gas pipe according to the operating conditions. The cooling operation and the heating operation are individually performed according to the request of the outdoor unit, and the heat source side heat exchanger is switched to the evaporator or the condenser on the outdoor unit side according to the change in the requirement of the whole room.

By the way, in a plurality of indoor unit units, when switching from cooling operation to heating operation or switching from heating operation to cooling operation, near the four-way valve and solenoid valve (open / close valve) that constitute the connection switching mechanism Since the pressure state changes suddenly, a loud noise (switching sound) is generated, which may cause discomfort to the user.
For this reason, it has been proposed to perform pressure equalization processing to reduce the pressure difference by stopping the operation of the compressor of the outdoor unit before cooling / heating switching. However, when the operation of the compressor of the outdoor unit is stopped, there is a problem that the air conditioning of the indoor unit that is not switched between cooling and heating cannot be maintained.
Further, in Patent Document 1, the refrigerant is bypassed from the high pressure gas pipe to the low pressure gas pipe, and then the cycle of the indoor heat exchanger is switched, so that the high pressure side pressure and the low pressure side pressure are equalized. It is proposed to switch between cooling and heating. However, even in this proposal, there is a problem that the air conditioning capability of the indoor unit that is not switched between cooling and heating is reduced.

Japanese Patent Publication No. 7-52046

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a multi-type air conditioner that can reduce switching sound without significantly reducing the air conditioning capability of an indoor unit that is not switched between cooling and heating. The purpose is to provide a machine.

For this purpose, the multi-type air conditioner of the present invention includes an outdoor unit including a compressor, an outdoor heat exchanger that performs heat exchange between the outside air and the refrigerant, and indoor air and refrigerant. A plurality of indoor unit units connected in parallel to the outdoor unit, a high-pressure gas pipe having one end connected to the discharge side of the compressor, and a compressor It is assumed that each of the low-pressure gas pipe having one end connected to the suction side and the indoor unit unit includes a plurality of connection switching mechanisms that control the refrigerant flow direction and selectively switch the cooling / heating operation.
In the multi-type air conditioner of the present invention, the connection switching mechanism has a first port connected to the high-pressure gas branch pipe branched from the main pipe of the high-pressure gas pipe, and a second port connected to the indoor heat exchanger side. A four-way valve formed with a third port connected to the low-pressure gas branch pipe branched from the main pipe of the low-pressure gas pipe and a fourth port connected to the low-pressure bypass pipe joining the low-pressure gas branch pipe A first on-off valve provided on the high-pressure gas branch pipe on the upstream side of the four-way valve; one end connected to the upstream side of the high-pressure gas branch pipe from the first on-off valve; A high-pressure bypass pipe having a second end connected to the downstream side and bypassing the first on-off valve; and a high-pressure gas branch pipe between the downstream side of the high-pressure bypass pipe and the first port of the four-way valve More than the position where one end is connected and the low pressure bypass pipe is connected A high-low pressure bypass pipe other end to the low pressure gas branch pipe flow side are connected, and a second on-off valve provided on the high-low pressure bypass pipe, comprising: a.

Here, the connection state of the four-way valve and the first on-off valve provided in the connection switching mechanism is switched in the connection state or switching in the open / close state. When this valve is switched, a switching sound is generated. Therefore, in response to this switching sound, the multi-type air conditioner according to the present invention is controlled as follows.
When switching any one of the indoor unit units that are in the cooling operation to the heating operation or vice versa, the four-way valve or the first one of the connection switching mechanism is opened by opening the second on-off valve that is normally closed. Reduce the differential pressure in the on-off valve. Thereby, the switching sound produced by the switching operation of the four-way valve and the opening / closing operation of the first opening / closing valve can be reduced.
More specifically, the multi-type air conditioner according to the present invention includes a control unit that controls the operation of the connection switching mechanism, and this control unit operates one of the indoor unit units that are in the cooling operation to the heating operation. At the time of switching, after the operation switching command is given, the step (a) of opening the closed second on-off valve and the connection of the first to fourth ports of the four-way valve after opening the second on-off valve A step (b) of switching the state from the cooling operation to the heating operation, and a step of closing the second on-off valve after switching the connection state of the first port to the fourth port from the cooling operation to the heating operation ( c).
By opening the second on-off valve, the refrigerant gas upstream from the first port of the four-way valve flows into the high and low pressure bypass pipe, and the differential pressure between the first port and the second port of the four-way valve is reduced, and the four-way valve Switching noise due to valve switching can be reduced.

  The switching sound when switching from the cooling operation to the heating operation is generated not only when the four-way valve is switched but also when the first opening / closing valve is opened / closed. Therefore, after the step (c), the control means of the multi-type air conditioner of the present invention lowers the operating capacity of the compressor of the outdoor unit, and after the operating capacity of the compressor is reduced, It is preferable to include a step (e) of opening the closed first on-off valve and a step (f) of increasing the operating capacity of the compressor of the outdoor unit after opening the first on-off valve. For example, the difference in the pressure of the gas refrigerant between the upstream side and the downstream side of the first on-off valve is reduced by reducing the rotational speed of the compressor to reduce the operating capacity of the compressor. Thereby, the switching sound at the time of switching a 1st on-off valve from closed to open is reduced.

  Further, when switching any one of the indoor unit units that are in the heating operation to the cooling operation, the control means closes the opened first on-off valve after the operation switching command is given (j) And the step (k) of opening the second on-off valve after the first on-off valve is closed. Then, the high-pressure gas refrigerant in the indoor heat exchanger flows into the low-pressure gas pipe, the differential pressure around the indoor four-way valve is reduced, and the switching sound due to the switching of the connection state of the subsequent indoor four-way valve can be reduced.

  After the step (k), the control means according to the present invention includes a step (l) for lowering the operating capacity of the compressor of the outdoor unit, and the first to second ports of the four-way valve after the operating capacity of the compressor is reduced. After switching the connection state of the four ports from the heating operation to the cooling operation (m), and changing the connection state of the first to fourth ports of the four-way valve from the heating operation to the cooling operation, the outdoor It is preferable to execute the step (n) of increasing the operating capacity of the compressor of the machine unit. This is to reduce the switching sound due to the switching of the four-way valve.

  The above-described multi-type air conditioner of the present invention is a four-way valve of a connection switching mechanism by reducing the capacity of the compressor without providing the above-described high / low pressure bypass pipe (including the second on-off valve) in the connection switching mechanism. Switching noise due to switching of the first on-off valve can be reduced. This multi-type air conditioner includes an outdoor unit that includes a compressor and an outdoor heat exchanger that exchanges heat between the outside air and the refrigerant, and an indoor heat that exchanges heat between the indoor air and the refrigerant. A plurality of indoor unit units including an exchanger and connected in parallel to the outdoor unit, a high-pressure gas pipe having one end connected to the discharge side of the compressor, and one end connected to the suction side of the compressor For each of the low-pressure gas pipe and the indoor unit, a plurality of connection switching mechanisms for selectively switching the cooling / heating operation by controlling the flow direction of the refrigerant, and the operations of the outdoor unit, the indoor unit, and the connection switching mechanism are controlled. Control means. This connection switching mechanism is branched from the first port connected to the high pressure gas branch pipe branched from the main pipe of the high pressure gas pipe, the second port connected to the indoor heat exchanger side, and the main pipe of the low pressure gas pipe. A four-way valve formed with a third port connected to the low-pressure gas branch pipe and a fourth port connected to the low-pressure bypass pipe joining the low-pressure gas branch pipe, and a high-pressure gas branch upstream of the four-way valve A first on-off valve provided on the pipe. The control means includes a step (o) for lowering the operating capacity of the compressor of the outdoor unit when switching any one of the indoor unit that is in the cooling operation to the heating operation, and the first one of the four-way valves. A step (p) of switching the connection state of the port to the fourth port from the cooling operation to the heating operation, a step (q) of opening the closed first on-off valve, and an outdoor portion after opening the first on-off valve And increasing the operation capacity of the compressor of the machine unit (r).

  The control means includes a step (u) of lowering the operation capacity of the compressor of the outdoor unit when switching any one of the indoor unit being operated to the cooling operation to the cooling operation, and the open first opening / closing operation Step (v) for closing the valve, Step (w) for switching the connection state of the first port to the fourth port of the four-way valve from the cooling operation to the heating operation, and the connection state of the first port to the fourth port Further, after switching from the cooling operation to the heating operation, the step (x) of increasing the operation capacity of the compressor of the outdoor unit can be executed.

  As described above, according to the present invention, it is possible to reduce the switching sound at the time of cycle switching in each indoor heat exchanger without reducing the air conditioning capability of the indoor unit that is not switched between cooling and heating.

  Hereinafter, an embodiment in which a multi-type air conditioner according to the present invention is applied to an air-conditioning / free multi-air conditioner (air conditioner) will be described with reference to the drawings.

  As shown in FIG. 1, an air conditioning free multi-air conditioner 200 (hereinafter simply referred to as an air conditioner 200) includes one outdoor unit 1, a plurality of indoor unit units 3 a to 3 g, and a high-pressure gas pipe 5 that connects these units, A low-pressure gas pipe 7 and a liquid pipe 9 are provided. Further, branch controllers (connection switching mechanisms) 46 a to 46 d for switching between the high pressure gas pipe 5 and the low pressure gas pipe 7 are provided between the outdoor unit 1 and the plurality of indoor unit 3. In FIG. 1, reference numerals 100a to 100d denote remote controllers. In addition, when naming the some indoor unit 3a-3g generically, it is only called the indoor unit 3. The same applies to other components such as the diversion controllers 46a to 46d.

  A plurality of indoor unit units 3 can be connected to each diversion controller 46. In the example of FIG. 1, four indoor unit units 3a to 3d are connected to the diversion controller 46a. In addition, one indoor unit 3e to 3g is connected to each of the diversion controllers 46b to 46d.

  In the air conditioner 200, the indoor unit units 3a to 3d, 3e, 3f, and 3g connected to the different diversion controllers 46a to 46d can be operated in different modes. On the other hand, indoor unit units connected to the same shunt controller 46, for example, in FIG. 1, indoor unit units 3a to 3d connected to the same shunt controller 46a are required to operate in the same mode. For example, when the indoor unit 3a is in the heating mode, the other indoor unit 3b to 3d is also required to operate in the heating mode.

  Next, a more specific configuration of the air conditioner 200 will be described with reference to FIGS. 2 and 3, for the sake of simplicity, only one indoor unit 3 is shown in the flow dividing controller 46a. Further, the configuration of the shunt controller 46 is omitted in FIGS. 2 and 5 and shown in FIGS.

The outdoor unit 1 includes two compressors 10 (10a, 10b) and two outdoor heat exchangers 12 (12a, 12b).
The outdoor heat exchanger 12 exchanges heat between the outdoor air and the refrigerant, and operates as a condenser or an evaporator depending on the state of the refrigerant that passes therethrough. Between the outdoor heat exchangers 12a and 12b and the liquid pipe 9 between the receivers 23 and in the vicinity of the outdoor heat exchangers 12a and 12b, outdoor expansion valves (expansion valves) 11a and 11b, respectively. Is provided. An electronic expansion valve is used as the outdoor expansion valve 11.

  Outdoor expansion valve bypass pipes 16a and 16b for bypassing the outdoor expansion valves 11a and 11b are provided, and the refrigerant flow from the outdoor heat exchangers 12a and 12b to the receiver 23 is allowed in the bypass pipes 16a and 16b. , Check valves 19a and 19b are provided to prevent the reverse flow. The outdoor expansion valve bypass pipe 16a connected to one outdoor heat exchanger 12a is provided with a bypass cutoff valve 21 that is an electromagnetic valve upstream of the check valve 19a.

The pipes connected to the receiver 23 side of the outdoor expansion valves 11 a and 11 b join at the junction 9 a of the liquid pipe 9.
In each of the outdoor heat exchangers 12a and 12b, liquid pipe side temperature sensors 30a and 30b provided on the liquid pipe 9 side, and four-way valve side temperature sensors 32a and 32b provided on the outdoor four-way valves 14a and 14b side, respectively. Is provided.
Further, an outdoor temperature sensor 34 for measuring the outdoor temperature, that is, the outdoor temperature, is provided in the vicinity of the outdoor heat exchangers 12a and 12b.

As each compressor 10a, 10b, it is preferable to use, for example, a scroll compressor. Two of these compressors 10a and 10b may be operated simultaneously depending on the required capacity, or only one unit may be operated and the other unit may be used as a backup.
The refrigerant compressed by the compressor 10 becomes a high-pressure gas refrigerant and is discharged to the high-pressure gas pipe 5. The high pressure gas pipe 5 is provided with a high pressure sensor PSH for measuring the pressure of the discharged refrigerant. The discharge pipes of the compressors 10a and 10b are provided with discharge pipe temperature sensors 36a and 36b for measuring the discharge pipe temperature.

  For example, R410A is used as the refrigerant used in the air conditioner 200 according to the present embodiment. This R410A has a density 1.4 (5 ° C.) times that of conventional refrigerants R22 and R407C, and is a high-density and high-pressure refrigerant capable of 1.6 (5 ° C.) times higher pressure. It has the advantages of exhibiting high refrigeration capacity and low pressure loss.

  The high-pressure gas pipe 5 located in the outdoor unit 1 branches at branch points 5a and 5b, and the branch pipes 6a and 6b are connected to the outdoor four-way valves 14a and 14b at the high-pressure gas pipe port 14-1. . The outdoor four-way valves 14a and 14b include an outdoor heat exchanger side port 14-2 connected to the outdoor heat exchangers 12a and 12b, and an outdoor low pressure gas branch pipe 15a that branches at a branch point 7d of the low pressure gas pipe 7, respectively. , 15b, a low pressure gas pipe side port 14-3, and a bypass pipe side port 14-4 connected to the outdoor low pressure gas branch pipes 15a, 15b via strainers 17a, 17b and capillary tubes 18a, 18b. It has.

  The low-pressure gas pipe 7 located in the outdoor unit 1 is connected to the compressors 10 a and 10 b via the accumulator 20. The liquid refrigerant recovered in the accumulator 20 is returned to the compressors 10a and 10b through the liquid refrigerant return lines 22a and 22b. A low pressure sensor PSL and a suction pipe temperature sensor 38 for measuring the low pressure of the system are provided on the upstream side of the accumulator 20 (that is, the suction pipe). The low pressure sensor PSL measures the refrigerant gas pressure drawn into the compressor 10.

  In the outdoor heat exchangers 12a and 12b, the liquid pipe 9 is connected to the side opposite to the side connected to the outdoor four-way valves 14a and 14b. The liquid pipe 9 in the outdoor unit 1 includes a receiver 23 that stores liquid refrigerant and a supercooler 25 that supercools the refrigerant flowing through the liquid pipe 9 during cooling operation. The subcooler 25 takes out a part of the liquid refrigerant flowing through the liquid pipe 9 and supercools the liquid refrigerant flowing through the liquid pipe 9 with the refrigerant that is expanded and vaporized by the expansion valve 25a and cooled. The gas refrigerant used for subcooling and vaporized is returned to the accumulator 20.

A plurality of indoor unit units 3 are provided. Each indoor unit 3 has the same configuration.
The indoor unit 3 includes an indoor heat exchanger 40 that exchanges heat with room air. The indoor heat exchanger 40 is provided with temperature sensors 33 and 35 for measuring the temperature before and after the indoor heat exchanger 40. In the vicinity of the indoor heat exchanger 40, an indoor temperature sensor 37 for measuring the indoor temperature is provided. An indoor expansion valve 42 is provided in the liquid refrigerant branch pipe 44 connecting the indoor heat exchanger 40 and the liquid pipe 9.

The shunt controller 46 has the following configuration (see FIGS. 3 and 4).
The diversion controller 46 includes an indoor four-way valve 48. The indoor four-way valve 48 includes a high-pressure gas pipe port 48-1 (first port) connected to the high-pressure gas branch pipe 5c branched from the main pipe of the high-pressure gas pipe 5, and a room connected to the indoor heat exchanger 40 side. A heat exchanger side port 48-2 (second port), a low pressure gas pipe port 48-3 (third port) connected to the indoor side low pressure gas branch pipe 7c branched from the main pipe of the low pressure gas pipe 7, A low-pressure bypass pipe port 48-4 (fourth port) connected to the low-pressure bypass pipe 50 that joins the midway position 49 of the indoor-side low-pressure gas branch pipe 7c.

  The indoor four-way valve 48 communicates the high-pressure gas pipe port 48-1 and the low-pressure bypass pipe port 48-4 during cooling operation (FIG. 3), and the indoor heat exchanger side port 48-2 and the low-pressure gas pipe port. Communicate with 48-3. Further, the indoor four-way valve 48 communicates the high-pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 during the heating operation (FIG. 4), and the low-pressure gas pipe port 48-3. The low-pressure bypass pipe port 48-4 is communicated.

The high-pressure gas branch pipe 5 c on the upstream side of the indoor four-way valve 48 is provided with a high-pressure gas branch pipe on-off valve (first on-off valve) 52. A high-pressure gas branch pipe bypass pipe (high-pressure bypass pipe) 54 is formed so as to bypass the high-pressure gas branch pipe on-off valve 52, and a first capillary tube 55 is provided in the high-pressure gas branch pipe bypass pipe 54. Yes. One end of the high-pressure gas branch pipe bypass pipe 54 is connected to the upstream side of the high-pressure gas branch pipe 5c from the high-pressure gas branch pipe on-off valve 52, and the other end is connected to the downstream side of the high-pressure gas branch pipe on-off valve 52c. The end is connected to bypass the on-off valve 52 for the high-pressure gas branch pipe.
A second capillary tube 57 is provided in the low pressure bypass pipe 50 on the downstream side of the indoor four-way valve 48.

  Between the high-pressure gas branch pipe 5c upstream of the high-pressure gas branch pipe bypass pipe 54 and the indoor low-pressure gas branch pipe 7c downstream of the low-pressure bypass pipe 50 (downstream of the midway position 49), A bypass pipe 58 is provided. The first high / low pressure bypass pipe 58 is provided with a first high / low pressure bypass opening / closing valve 60 and a third capillary tube 62 in order from the high pressure gas branch pipe 5c side toward the indoor side low pressure gas branch pipe 7c side. .

  One end is connected to the high-pressure gas branch pipe 5c between the downstream side of the high-pressure gas branch pipe bypass pipe 54 and the high-pressure gas pipe port 48-1 of the indoor four-way valve 48, and the downstream side of the low-pressure bypass pipe 50 (at the midway position 49). A second high / low pressure bypass pipe (high / low pressure bypass pipe) 63 whose other end is connected to the indoor side low pressure gas branch pipe 7c on the downstream side is provided. The second high / low pressure bypass pipe 63 includes a second high / low pressure bypass open / close valve (second open / close valve) 64 and a fourth capillary tube 65 from the high pressure gas branch pipe 5c side toward the indoor side low pressure gas branch pipe 7c side. Are provided in order.

  As shown in FIG. 5, the air conditioner 200 includes an outdoor control device CL1 that controls the outdoor unit 1 and an indoor control device CL2 that controls the indoor unit 3. In the present embodiment, one indoor control device CL2 is provided for each of the indoor unit units 3a to 3d, and one indoor control unit CL2 is provided for each of the indoor unit units 3e, 3f, and 3g. The outdoor control device CL1 and the indoor control device CL2 communicate with each other. In FIG. 5, the same components as those used in FIGS. 2 to 4 are denoted by the same reference numerals, and the description thereof is omitted. Further, only one of the outdoor heat exchangers 12a and 12b, the compressors 10a and 10b, and the outdoor four-way valves 14a and 14b is shown in FIG.

The outdoor control device CL1 includes a control unit 70 and an input unit 72.
The control unit 70 calculates each control value based on the data obtained from the input unit 72. This control value is sent to each control device such as the outdoor expansion valve 11a, the outdoor fan F1, the outdoor four-way valve 14a, and the compressor 10a. Each calculation result of the control unit 70 is sent to the input unit 82 of the indoor control device CL2.
The input unit 72 includes a liquid pipe side temperature sensor 30a provided in the outdoor heat exchanger 12a, a four-way valve side temperature sensor 32a, an outdoor temperature sensor 34 provided in the vicinity of the outdoor heat exchanger 12a, and a discharge from the compressor 10a. Output values of the discharge pipe temperature sensor 36a, the high pressure sensor PSH provided in the pipe, the low pressure sensor PSL provided on the upstream side of the accumulator 20, and the suction pipe temperature sensor 38 are input.

The indoor control device CL2 includes a control unit 80 and an input unit 82.
The control unit 80 calculates each control value based on the data obtained from the input unit 82. This control value is sent to control devices such as the indoor expansion valve 42, the indoor fan F2, and the indoor four-way valve 48 of the shunt controller 46. Each calculation result of the control unit 80 is sent to the input unit 72 of the outdoor control device CL1.
The output values of the temperature sensors 33 and 35 and the indoor temperature sensor 37 provided in the indoor heat exchanger 40 are input to the input unit 82.

  The outdoor control device CL1 and the indoor control device CL2 include at least a CPU as an arithmetic processing device, a RAM as a main storage device, and a recording medium on which a program for operating the air conditioner 200 is recorded. Each of the outdoor control device CL1 and the indoor control device CL2 reads the program recorded in the storage medium and executes information processing / calculation processing, thereby operating the air conditioner 200 in accordance with the purpose.

  The air conditioner 200 is an operation pattern in which the cooling operation is selected in all the indoor unit units 3 (all cooling all units operation), the intermediate period such as spring or autumn, and the number of indoor unit units 3 that perform the cooling operation. Is an operation pattern (cooling main operation) in which the cooling operation is performed more than the number of indoor unit units 3 performing the heating operation, and an operation pattern in which the heating operation is selected in all indoor unit units 3 as in winter ( All heating unit operation), the number of indoor unit 3 that performs the heating operation is larger than the number of indoor unit units 3 that perform the cooling operation, the operation pattern of heating main (heating main), the cooling operation of the indoor unit 3 The operation is performed according to various operation patterns such as an operation pattern (cooling / heating balance) performed at the time of cooling / heating balance in which the number of people performing the heating operation is equal.

FIG. 2 shows a cooling / heating balance operation pattern. In this operation pattern, the required cooling capacity is not large as in the summer, and therefore the required condensation capacity is relatively small (for example, 50% of the capacity), so one of the outdoor heat exchangers 12b is stopped.
The second outdoor heat exchanger 12b is stopped as follows.
The outdoor four-way valve 14b connected to the second outdoor heat exchanger 12b is switched (is connected to the outdoor four-way valve 14b and turned ON), and the high-pressure gas pipe port 14-1 and the outdoor heat exchanger side port 14-2 are connected. The communication is cut off, the high pressure gas pipe port 14-1 and the bypass pipe side port 14-4 are communicated, and the outdoor heat exchanger side port 14-2 and the low pressure gas pipe side port 14-3 are communicated. This prevents the high-pressure gas discharged from the compressor 10a from flowing into the second outdoor heat exchanger 12b. Further, the outdoor expansion valve 11b connected to the second outdoor heat exchanger 12b is fully closed.

  The outdoor expansion valve 11a on the downstream side of the other first outdoor heat exchanger 12a is fully opened, and the bypass cutoff valve 21 provided in the outdoor expansion valve bypass pipe 16a is also opened.

  The high-pressure gas refrigerant compressed by the compressor 10a branches at the branch points 5a and 5b of the high-pressure gas pipe 5 and flows to the outdoor four-way valves 14a and 14b. On the other hand, a part (very small amount) of the high-pressure gas refrigerant flows to the indoor unit 3 through the high-pressure gas pipe 5 connected to the indoor unit 3. In the outdoor four-way valves 14a and 14b, the high pressure gas pipe port 14-1 and the outdoor heat exchanger side port 14-2 are communicated with each other, and the low pressure gas pipe side port 14-3 and the bypass pipe side port 14-4 are communicated with each other. Has been. In this case, the outdoor four-way valves 14a and 14b, which are electromagnetic valves, are turned off without being conducted.

  Therefore, the high-pressure gas refrigerant that has flowed into the high-pressure gas pipe port 14-1 passes through the outdoor heat exchanger side port 14-2 and is guided to the outdoor heat exchanger 12a. On the other hand, the low pressure gas pipe side port 14-3 and the bypass pipe side port 14-4 of the outdoor four-way valves 14a, 14b are communicated, and the pipes passing through the outdoor low pressure gas branch pipes 15a, 15b are closed loops. The high pressure gas refrigerant does not flow into the outdoor low pressure gas branch pipes 15 a and 15 b, and the low pressure gas refrigerant does not flow from the branch point 7 d of the low pressure gas pipe 7. However, the inside of the outdoor low-pressure gas branch pipes 15a and 15b is filled with the low-pressure gas refrigerant.

  The high-pressure gas refrigerant that has flowed into the outdoor heat exchanger 12a exchanges heat with the outside air to dissipate heat and is condensed and liquefied. In this case, both the outdoor expansion valves 11a and 11b are fully opened, and the condensed high-pressure liquid refrigerant passes through the receiver 23 and passes through the receiver 23 and is supercooled by the subcooler 25, and then the liquid pipe 9 Then, it is guided to the indoor unit 3. If the liquid pipe 9 connecting the outdoor unit 1 and the indoor unit 3 is long, a supercooler 25 is attached to avoid evaporation of the liquid refrigerant in the liquid pipe 9. desirable.

The high-pressure liquid refrigerant that has flowed into the indoor unit 3f that is in the cooling operation flows as follows (see FIGS. 2 and 3).
The high-pressure liquid refrigerant branches off to the liquid refrigerant branch pipe 44 connected to the indoor unit 3f, and is then throttled and expanded by the indoor expansion valve 42 of the indoor unit 3f. Thereafter, the liquid refrigerant evaporates in the indoor heat exchanger 40, takes heat from the indoor air, and cools it. The vaporized low-pressure gas refrigerant flows into the indoor four-way valve 48 of the shunt controller 46. The indoor four-way valve 48 connects the high-pressure gas pipe port 48-1 and the low-pressure bypass pipe port 48-4, and connects the indoor heat exchanger side port 48-2 and the low-pressure gas pipe port 48-3. Yes. Therefore, the low-pressure gas refrigerant from the indoor heat exchanger 40 flows through the indoor four-way valve 48 to the indoor-side low-pressure gas branch pipe 7c, and then passes through the low-pressure gas pipe 7 that is the main pipe to the outdoor unit 1. Led. The high-pressure liquid refrigerant flows in the indoor unit 3g in the same manner.

In the shunt controller 46 of the indoor unit 3f that is in the cooling operation, the high-pressure gas refrigerant flows as follows (see FIG. 3). The high-pressure gas refrigerant that has flowed from the high-pressure gas pipe 5 through the high-pressure gas branch pipe 5c branched to each indoor unit 3 has the high-pressure gas branch pipe open / close valve 52 closed, so the high-pressure gas branch pipe bypass pipe 54 is closed. And the pressure is reduced by the first capillary tube 55. The decompressed gas refrigerant flows into the low-pressure bypass pipe 50 through the indoor four-way valve 48, is throttled by the second capillary tube 57 and adjusted in flow rate, and then joins the indoor-side low-pressure gas branch pipe 7c at the midway position 49. To do.
On the other hand, since the first high / low pressure bypass on / off valve 60 of the shunt controller 46 is closed, the high pressure gas refrigerant does not flow through the first high / low pressure bypass pipe 58.

  The low-pressure gas refrigerant flowing into the outdoor unit 1 through the low-pressure gas pipe 7 is returned to the compressor 10 a after gas-liquid separation by the accumulator 20.

Further, the diversion controller 46a of the indoor unit 3a that performs the heating operation is operated as follows (see FIG. 4).
The indoor four-way valve 48 of the shunt controller 46 allows the high-pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 to communicate with each other, and the low-pressure gas pipe port 48-3 and the low-pressure bypass pipe port 48-4. Is in communication. Therefore, the high-pressure gas refrigerant supplied from the high-pressure gas pipe 5 is led to the indoor heat exchanger 40 through the indoor four-way valve 48, and is condensed and liquefied by the indoor heat exchanger 40 to heat the indoor air. Give the heating. The high-pressure liquid refrigerant liquefied by the indoor heat exchanger 40 passes through the liquid refrigerant branch pipe 44 and joins the liquid pipe 9 that is the main pipe.

<First embodiment (switching from cooling to heating)>
As described above, in the air conditioner 200 that is in the cooling / heating balance operation, each device when the indoor unit 3f (or 3g) that is in the cooling operation is instructed to be switched to the heating operation by the operation of the remote controller 100f. Will be described with reference to FIG.
The control of the operation of this device is realized by the indoor control device CL2, but instead of this or in cooperation with this, the outdoor control device CL1, the remote controller 100, or an external device other than these devices. It can also be performed by a device.

  As shown in FIG. 6, the indoor unit 3f is initially in a cooling operation, and the compressor 10a is driven by PI control. At this time, the indoor four-way valve 48 of the corresponding diversion controller 46f allows the high-pressure gas pipe port 48-1 and the low-pressure bypass pipe port 48-4 to communicate with each other, and the indoor heat exchanger side port 48-2 and the low-pressure gas pipe use. The port 48-3 is in communication (this state is indicated as “OFF” in FIG. 6). Further, the high pressure gas branch pipe on / off valve 52, the first high / low pressure bypass on / off valve 60, and the second high / low pressure bypass on / off valve 64 of the branch flow controller 46f are all closed.

  During this cooling operation, if the remote controller 100f commands the operation of the indoor unit 3f to be switched to heating (indoor unit operation mode “cold” → “warm”), the second high of the shunt controller 46f The low pressure bypass on / off valve 64 is opened (ON). By doing so, the refrigerant gas upstream from the high-pressure gas pipe port 48-1 (first port) of the indoor four-way valve 48 flows into the second high-low pressure bypass pipe 63, and the high-pressure gas pipe port 48- 1, the indoor heat exchanger side port 48-2, the low pressure gas pipe port 48-3, and the low pressure bypass pipe port 48-4 are reduced. After the time T1 has elapsed since the opening of the second high / low pressure bypass on / off valve 64, the connection state of the indoor four-way valve 48 is switched to heating. That is, the high pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 are communicated, and the low pressure gas pipe port 48-3 and the low pressure bypass pipe port 48-4 are communicated. As described above, the pressure difference among the high pressure gas pipe port 48-1, the indoor heat exchanger side port 48-2, the low pressure gas pipe port 48-3, and the low pressure bypass pipe port 48-4 of the indoor four-way valve 48 is reduced. Since it is small, the switching sound can be reduced. After the connection state of the indoor four-way valve 48 is switched to heating, the second high / low pressure bypass opening / closing valve 64 is closed (OFF) after the time T2 has elapsed.

After the time T3 has elapsed since the second high / low pressure bypass opening / closing valve 64 was closed, the operating frequency (Hz) of the compressor 10a is lowered to lower the rotational speed of the compressor 10a. By reducing the capacity of the compressor 10a, the differential pressure of the gas refrigerant between the upstream side and the downstream side of the high-pressure gas branch pipe on-off valve 52 is reduced. In the present embodiment, the operating frequency (Hz) of the compressor 10a is maintained at a predetermined value for a predetermined time after being continuously reduced to a predetermined value, but the differential pressure between the high pressure side and the low pressure side is maintained. If it can be made low, it is not limited to this form. Moreover, the method of reducing the capability of the compressor 10a is not limited to reducing the rotation speed of the compressor 10a. Furthermore, the operating frequency (Hz) of the compressor 10a can be appropriately controlled while detecting the differential pressure.
After the operating frequency (Hz) of the compressor 10a is lowered and the time T4 has elapsed, the high-pressure gas branch pipe on-off valve 52 is opened (ON). Thereby, the diversion controller 46f completes switching to the heating operation. At this time, since the differential pressure of the gas refrigerant between the upstream side and the downstream side of the high-pressure gas branch pipe on-off valve 52 is small, the switching sound can be reduced.

  After the time T5 has elapsed since the opening / closing valve 52 for the high-pressure gas branch pipe is opened, the operating frequency of the compressor 10a is increased to perform a regular heating operation. Heretofore, the compressor 10a is not stopped.

<First embodiment (switching from heating to cooling)>
Next, in the air conditioner 200 that is in a cooling / heating balance operation, each device when the indoor unit 3a (or 3e) that is in the heating operation is instructed to be switched to the cooling operation by the operation of the remote controller 100a (or 100e). Will be described with reference to FIG.
As shown in FIG. 7, the indoor unit 3a is initially operated for heating, and the compressor 10a is driven by PI control. At this time, the indoor four-way valve 48 of the corresponding diversion controller 46a communicates the high-pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2, and the low-pressure gas pipe port 48-3 and the low-pressure bypass pipe. The port 48-4 is in communication (this state is indicated as “ON” in FIG. 7). In the branch flow controller 46a, the high-pressure gas branch pipe opening / closing valve 52 is open (ON), and the first high / low pressure bypass opening / closing valve 60 and the second high / low pressure bypass opening / closing valve 64 are closed (OFF).

  During this heating operation, the remote controller 100a gives a command to switch the operation of the indoor unit 3a to cooling (indoor unit operation mode “warm” → “cold”), and then the current is diverted after the time T6 has elapsed. The on-off valve 52 for the high-pressure gas branch pipe of the controller 46a is closed (OFF). At the same time (or later), the second high / low pressure bypass on / off valve 64 is opened (ON). By doing so, the high-pressure gas refrigerant in the indoor heat exchanger 40 flows into the low-pressure gas pipe 7 (the indoor-side low-pressure gas branch pipe 7 c) via the second high-low pressure bypass pipe 63. Therefore, the differential pressure between the high-pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 becomes small, and the switching sound at the time of switching the connection state of the indoor four-way valve 48 to be performed later can be reduced. it can.

After the time T7 has elapsed since the opening of the second high / low pressure bypass opening / closing valve 64, the operating frequency (Hz) of the compressor 10a is lowered to lower the rotational speed of the compressor 10a. This is to reduce the differential pressure between the high pressure side and the low pressure side by reducing the capacity of the compressor 10a. When the time T8 has elapsed since the operating frequency (Hz) of the compressor 10a was lowered, the connection state of the indoor four-way valve 48 is switched to cooling. That is, the high pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 are communicated, and the low pressure gas pipe port 48-3 and the low pressure bypass pipe port 48-4 are communicated.
At the same time (or later), the second high / low pressure bypass on / off valve 64 is closed (OFF).

  After the time T9 has elapsed since the connection state of the indoor four-way valve 48 is switched to cooling and the second high / low pressure bypass on / off valve 64 is closed, the operating frequency of the compressor 10a is increased to perform normal cooling operation. . Heretofore, the compressor 10a is not stopped.

  As described above, according to the present embodiment, when switching from the cooling operation to the heating operation, the switching sound is generated by opening the second high / low pressure bypass opening / closing valve 64 for switching the preceding indoor four-way valve 48. The switching noise is reduced by lowering the capacity of the compressor 10 for the subsequent switching of the on-off valve 52 for the high-pressure gas branch pipe. Further, according to the present embodiment, when switching from the heating operation to the cooling operation, in addition to opening the second high / low pressure bypass opening / closing valve 64 with respect to the switching of the indoor four-way valve 48, the capacity of the compressor 10 is lowered. This reduces the switching sound. Therefore, according to this embodiment, there is no discomfort to the user when switching between cooling and heating. Also, in this embodiment, the capacity of the compressor 10 is lowered. However, since the period is short, a decrease in the air conditioning capacity of the indoor unit 3 irrespective of switching between cooling and heating can be minimized.

<Second embodiment (switching from cooling to heating)>
In the first embodiment described above, opening / closing (ON, OFF) the second high / low pressure bypass opening / closing valve 64 of the second high / low pressure bypass pipe 63 and lowering the rotational speed of the compressor 10a. In combination, the switching sound of the indoor four-way valve 48 and the switching sound of the high-pressure gas branch pipe opening / closing valve 52 are both reduced. As will be described below, the present invention is not limited to this, and it is possible to reduce both the switching sound of the indoor four-way valve 48 and the switching sound of the on-off valve 52 for the high-pressure gas branch pipe only by reducing the rotational speed of the compressor 10a. Can be realized. In addition, this embodiment is realizable with the shunt controller 46 which does not provide the 2nd high and low pressure bypass pipe 63. FIG.

  As shown in FIG. 8, the indoor unit 3f is initially in a cooling operation. At this time, the indoor four-way valve 48 of the corresponding diversion controller 46f allows the high-pressure gas pipe port 48-1 and the low-pressure bypass pipe port 48-4 to communicate with each other, and the indoor heat exchanger side port 48-2 and the low-pressure gas pipe use. The port 48-3 is in communication (this state is indicated as “OFF” in FIG. 8). Further, the high-pressure gas branch pipe on-off valve 52 and the first high-low pressure bypass on-off valve 60 of the branch flow controller 46f are closed.

  During this cooling operation, if the remote controller 100f commands the operation of the indoor unit 3f to be switched to heating (indoor unit operation mode “cold” → “warm”), the operating frequency of the compressor 10a ( Hz) is lowered to lower the rotational speed of the compressor 10a. After the time T11 has elapsed since the operating frequency (Hz) of the compressor 10a was lowered, the connection state of the indoor four-way valve 48 is switched to heating. That is, the high pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 are communicated, and the low pressure gas pipe port 48-3 and the low pressure bypass pipe port 48-4 are communicated. Since the capacity of the compressor 10a is lowered, the switching sound due to switching of the indoor four-way valve 48 can be reduced.

  After switching the connection state of the indoor four-way valve 48 to heating, the high-pressure gas branch pipe opening / closing valve 52 is opened (ON) after a time T12 as a pressure equalizing time has elapsed. Thereby, the diversion controller 46f completes switching to the heating operation. Also at this time, since the capacity of the compressor 10a is lowered, the switching sound due to switching of the indoor four-way valve 48 can be reduced.

  After the time T13 has elapsed since the opening / closing valve 52 for the high-pressure gas branch pipe has been opened, the operating frequency of the compressor 10a is increased to perform regular heating operation. Heretofore, the compressor 10a is not stopped.

<Second embodiment (switching from heating to cooling)>
Next, the operation of each device when the indoor unit 3a (or 3e) in the heating operation is instructed to switch to the cooling operation by the operation of the remote controller 100a (or 100e) will be described based on FIG. .
As shown in FIG. 9, the indoor unit 3a is initially heated. At this time, the indoor four-way valve 48 of the corresponding diversion controller 46a communicates the high-pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2, and the low-pressure gas pipe port 48-3 and the low-pressure bypass pipe. The port 48-4 is in communication (this state is indicated as “ON” in FIG. 9). In the branch flow controller 46a, the high-pressure gas branch pipe opening / closing valve 52 is open (ON), and the first high / low pressure bypass opening / closing valve 60 is closed (OFF).

  During this heating operation, if the remote controller 100a instructs to switch the operation of the indoor unit 3a to heating (indoor unit operation mode “warm” → “cold”), the operating frequency of the compressor 10a ( Hz) is lowered to lower the rotational speed of the compressor 10a. After the time T15 has elapsed since the operating frequency (Hz) of the compressor 10a was lowered, the on-off valve 52 for the high-pressure gas branch pipe of the shunt controller 46a is closed (OFF). Since the capacity of the compressor 10a is reduced, it is possible to reduce the switching sound caused by switching the on / off valve 52 for the high pressure gas branch pipe from ON to OFF.

  After the time T16 has elapsed since the high-pressure gas branch pipe opening / closing valve 52 has been switched to cooling, the connection state of the indoor four-way valve 48 is switched to cooling. That is, the high pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 are communicated, and the low pressure gas pipe port 48-3 and the low pressure bypass pipe port 48-4 are communicated. Thereby, the diversion controller 46f completes the switching to the cooling operation. Also at this time, since the capacity of the compressor 10a is lowered, the switching sound due to switching of the indoor four-way valve 48 can be reduced.

  After the time T17 has elapsed since the connection state of the indoor four-way valve 48 is switched to cooling, the operating frequency of the compressor 10a is increased to increase the cooling operation capability. Heretofore, the compressor 10a is not stopped.

  As described above, according to the present embodiment, when switching from the cooling operation to the heating operation, and when switching from the heating operation to the cooling operation, the indoor four-way valve 48 and the high-pressure gas branch pipe on-off valve 52 are sequentially switched. Prior to this, the switching sound is reduced by reducing the capacity of the compressor 10. Therefore, according to this embodiment, the user is not uncomfortable when switching between cooling and heating. Further, in the present embodiment, it is not necessary to provide the second high / low pressure bypass pipe 63 as in the first embodiment, so that the flow dividing controller 46 can be simplified.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not restricted to embodiment demonstrated, A change can be added in the range which does not deviate from the summary of this invention. For example, if the outdoor expansion valve 11 of the outdoor unit 1 is open at the time of cooling / heating switching, noise flows due to the refrigerant flowing through the outdoor expansion valve 11. Therefore, in order to reduce the noise at the time of switching between cooling and heating including the outdoor unit 1, it is preferable to close the outdoor expansion valve 11 during, for example, the periods T3 and T4 in FIG.

It is a figure which shows the whole schematic structure of the air conditioning free multi air conditioner which concerns on embodiment of this invention. It is a figure which shows the whole schematic structure of the air conditioning free multi air conditioner which concerns on embodiment of this invention, and is a figure which shows the driving | running pattern in which cooling and heating were balanced. It is a figure which shows the structure of the shunt controller corresponding to the indoor unit in air_conditionaing | cooling operation. It is a figure which shows the structure of the shunt controller corresponding to the indoor unit which is heating-operated. It is the figure which showed the control block of the air conditioning free multi air conditioner concerning embodiment of this invention. It is a figure which shows operation | movement of each apparatus when a specific indoor unit is switched from air_conditioning | cooling to heating in the air conditioning free multi air conditioner which concerns on embodiment of this invention. It is a figure which shows operation | movement of each apparatus when a specific indoor unit is switched from heating to cooling in the air conditioning free multi air conditioner which concerns on embodiment of this invention. It is a figure which shows operation | movement of each apparatus when the specific indoor unit is switched from air_conditioning | cooling to heating in the air conditioning free multi air conditioner which concerns on other embodiment of this invention. It is a figure which shows operation | movement of each apparatus when the specific indoor unit is switched from heating to cooling in the air conditioning free multi air conditioner which concerns on other embodiment of this invention.

Explanation of symbols

200 ... air conditioning free multi air conditioner,
DESCRIPTION OF SYMBOLS 1 ... Outdoor unit, 3a-3g ... Indoor unit, 5 ... High pressure gas pipe, 5c ... High pressure gas branch pipe, 7 ... Low pressure gas pipe, 7c ... Indoor low pressure gas branch pipe, 9 ... Liquid pipe,
10a, 10b ... compressor, 12a, 12b ... outdoor heat exchanger, 14a, 14b ... outdoor four-way valve, 15a, 15b ... outdoor low-pressure gas branch pipe,
DESCRIPTION OF SYMBOLS 40 ... Indoor heat exchanger, 46a-46g ... Shunt controller, 48 ... Indoor four-way valve, 48-1 ... High pressure gas pipe port, 48-2 ... Indoor heat exchanger side port, 48-3 ... Low pressure gas pipe port, 48 -4 ... Port for low pressure bypass pipe, 50 ... Low pressure bypass pipe, 52 ... Open / close valve for high pressure gas branch pipe, 54 ... Bypass pipe for high pressure gas branch pipe, 58 ... First high / low pressure bypass pipe, 60 ... First high / low pressure bypass open / close valve 63 ... second high / low pressure bypass pipe, 64 ... second high / low pressure bypass on-off valve,
CL1 ... outdoor control device CL2 ... indoor control device

Claims (7)

An outdoor unit comprising a compressor and an outdoor heat exchanger for exchanging heat between the outside air and the refrigerant;
A plurality of indoor unit units including an indoor heat exchanger for exchanging heat between indoor air and the refrigerant, and connected in parallel to the outdoor unit;
A high-pressure gas pipe having one end connected to the discharge side of the compressor;
A low-pressure gas pipe having one end connected to the suction side of the compressor;
For each of the indoor unit, a plurality of connection switching mechanisms for selectively switching the cooling and heating operation by controlling the flow direction of the refrigerant,
The connection switching mechanism is
A first port connected to the high-pressure gas branch pipe branched from the main pipe of the high-pressure gas pipe; a second port connected to the indoor heat exchanger side; and a low-pressure gas branched from the main pipe of the low-pressure gas pipe A four-way valve formed with a third port connected to the branch pipe and a fourth port connected to the low-pressure bypass pipe joining the low-pressure gas branch pipe;
A first on-off valve provided on the high-pressure gas branch pipe upstream of the four-way valve;
One end is connected to the upstream side of the high-pressure gas branch pipe from the first on-off valve, and the other end is connected to the downstream side of the high-pressure gas branch pipe from the first on-off valve, bypassing the first on-off valve A high-pressure bypass pipe,
One end of the high-pressure gas branch pipe between the downstream side of the high-pressure bypass pipe and the first port of the four-way valve is connected, and the low-pressure gas branch pipe downstream from the position where the low-pressure bypass pipe is connected. A high and low pressure bypass pipe with the other end connected to
A second on-off valve provided on the high / low pressure bypass pipe;
A multi-type air conditioner comprising: Control means for controlling the operation of the connection switching mechanism;
The control means, when switching the operation of any of the indoor unit that is in the cooling operation to the heating operation,
(A) opening the closed second on-off valve after the operation switching command is made;
After opening the second on-off valve, switching the connection state of the first port to the fourth port of the four-way valve from cooling operation to heating operation (b);
(C) closing the second on-off valve after switching the connection state of the first port to the fourth port from cooling operation to heating operation;
The multi-type air conditioner according to claim 1, wherein: The control means includes
After step (c),
Reducing the operating capacity of the compressor of the outdoor unit (d);
(E) opening the first on-off valve that has been closed after the operating capacity of the compressor has been reduced;
Increasing the operating capacity of the compressor of the outdoor unit after opening the first on-off valve;
The multi-type air conditioner according to claim 2, wherein: Control means for controlling the operation of the connection switching mechanism;
The control means, when switching the operation of any of the indoor unit that is heating operation to cooling operation,
A step (j) of closing the opened first on-off valve after the operation switching command is given;
(K) opening the second on-off valve after the first on-off valve is closed;
The multi-type air conditioner according to claim 1, wherein: The control means includes
After step (k)
Reducing the operating capacity of the compressor of the outdoor unit (l);
After the operating capacity of the compressor is reduced, the step (m) of switching the connection state of the first port to the fourth port of the four-way valve from heating operation to cooling operation;
Increasing the operating capacity of the compressor of the outdoor unit after switching the connection state of the first port to the fourth port of the four-way valve from heating operation to cooling operation;
The multi-type air conditioner according to claim 4, wherein: An outdoor unit comprising a compressor and an outdoor heat exchanger for exchanging heat between the outside air and the refrigerant;
A plurality of indoor unit units including an indoor heat exchanger for exchanging heat between indoor air and the refrigerant, and connected in parallel to the outdoor unit;
A high-pressure gas pipe having one end connected to the discharge side of the compressor;
A low-pressure gas pipe having one end connected to the suction side of the compressor;
For each of the indoor unit, a plurality of connection switching mechanisms for selectively switching the cooling and heating operation by controlling the flow direction of the refrigerant,
Control means for controlling the operation of the outdoor unit, the indoor unit and the connection switching mechanism,
The connection switching mechanism is
A first port connected to the high-pressure gas branch pipe branched from the main pipe of the high-pressure gas pipe; a second port connected to the indoor heat exchanger side; and a low-pressure gas branched from the main pipe of the low-pressure gas pipe A four-way valve formed with a third port connected to the branch pipe and a fourth port connected to the low-pressure bypass pipe joining the low-pressure gas branch pipe;
A first on-off valve provided on the high-pressure gas branch pipe upstream of the four-way valve;
With
The control means includes
When switching any one of the indoor unit units that are in cooling operation to heating operation,
Reducing the operating capacity of the compressor of the outdoor unit (o);
Switching the connection state of the first port to the fourth port of the four-way valve from cooling operation to heating operation (p);
Opening the first on-off valve that has been closed (q);
Increasing the operating capacity of the compressor of the outdoor unit after opening the first on-off valve (r);
A multi-type air conditioner characterized in that The control means includes
When switching the operation of any of the indoor unit that is heating operation to cooling operation,
Reducing the operating capacity of the compressor of the outdoor unit (u);
Closing the open first on-off valve (v);
Switching the connection state of the first port to the fourth port of the four-way valve from cooling operation to heating operation (w);
(X) increasing the operating capacity of the compressor of the outdoor unit after switching the connection state of the first port to the fourth port from cooling operation to heating operation;
The multi-type air conditioner according to claim 6, wherein:

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