JP7544100B2 - Air Conditioning Equipment - Google Patents

Description

The present invention relates to an air conditioner equipped with multiple outdoor units each connected to multiple indoor units via refrigerant piping.

Air conditioners are known that are equipped with multiple indoor units and can switch between an operating mode in which all indoor units perform either cooling or heating (hereinafter also referred to as a cooling/heating switching mode), and an operating mode that allows each indoor unit to selectively perform either cooling or heating (hereinafter also referred to as a cooling/heating free mode). For example, Patent Document 1 discloses an air conditioner that can support both the cooling/heating switching mode and the cooling/heating free mode with a single outdoor unit.

An air conditioner with a free-heating and cooling system can selectively perform full heating operation, full cooling operation, heating-dominated operation, and cooling-dominated operation. Full heating operation is an operation mode in which all indoor units perform heating operation, and full cooling operation is an operation mode in which all indoor units perform cooling operation. Heating-dominated operation is an operation mode performed when indoor units performing cooling operation and indoor units performing heating operation are mixed, and the total capacity required by the indoor units performing heating operation exceeds the total capacity required by the indoor units performing cooling operation. And cooling-dominated operation is an operation mode performed when indoor units performing cooling operation and indoor units performing heating operation are mixed, and the total capacity required by the indoor units performing cooling operation exceeds the total capacity required by the indoor units performing heating operation.

The configuration of the refrigerant circuit is different between outdoor units that use the cooling/heating switching system and outdoor units that use the cooling/heating free system. In the cooling/heating switching system, there are two connection pipes (a gas pipe and a liquid pipe) connecting each indoor unit to the outdoor unit, whereas in the cooling/heating free system, there are three connection pipes connecting each indoor unit to the outdoor unit: two gas pipes (a high-pressure gas pipe and a low-pressure gas pipe) and one liquid pipe.

In the heating and cooling free system, refrigerant flows through each refrigerant pipe as follows depending on the operating mode. First, the high-pressure gas pipe is a connecting pipe through which high-pressure gas refrigerant discharged from the compressor flows during heating only operation, heating-dominated operation, and cooling-dominated operation. The low-pressure gas pipe is a connecting pipe through which low-pressure gas refrigerant flows out of the indoor heat exchanger that functions as an evaporator during cooling only operation and cooling-dominated operation. The liquid pipe is a refrigerant pipe through which intermediate-pressure liquid refrigerant flows out of the outdoor heat exchanger that functions as a condenser during cooling only operation and cooling-dominated operation, and is a connecting pipe through which intermediate-pressure liquid refrigerant flows into the outdoor heat exchanger that functions as an evaporator during heating only operation and heating-dominated operation.

The number of these connecting pipes used (number of connections) is determined by the selected operating mode (cooling/heating switching mode/cooling/heating free mode), and the refrigerant circuit of the outdoor unit is switched between the refrigerant circuit for the cooling/heating switching mode and the refrigerant circuit for the cooling/heating free mode by a flow path switching valve built into the outdoor unit.

JP 2008-111589 A

In recent years, the development of air conditioners that can support both the cooling/heating switching system and the cooling/heating free system has been progressing. In this type of air conditioner, all outdoor units must be standardized to either the cooling/heating switching system or the cooling/heating free system during operation. Generally, outdoor units that can support both the cooling/heating switching system and the cooling/heating free system are provided with a switching means such as a dip switch that switches the refrigerant circuit to either the cooling/heating switching system or the cooling/heating free system, and it is assumed that the switching means will be operated by an operator for each outdoor unit during installation. However, due to an operation error or forgetting to operate the switching means, there may be cases where the air conditioner is operated in a state where all outdoor units are not standardized to either the cooling/heating switching system or the cooling/heating free system.

For example, if an air conditioner that operates in the cooling/heating free mode is mixed with an outdoor unit that uses a cooling/heating switching mode, the high-pressure refrigerant flowing out of the outdoor unit that uses the cooling/heating free mode may flow into the gas pipe of the outdoor unit that uses the cooling/heating switching mode, causing the low pressure to rise and exceeding the operating range of the compressor's performance. In addition, as the low pressure rises, the high pressure also rises, causing the temperature of the refrigerant discharged from the compressor to exceed the operating range. In addition, if an air conditioner that operates in the cooling/heating free mode is mixed with an outdoor unit that uses the cooling/heating free mode, the refrigerant and refrigeration oil may not return to the outdoor unit due to the refrigerant piping not being connected to the low-pressure gas pipe of the outdoor unit that uses the cooling/heating free mode, resulting in an excessive drop in low pressure and a shortage of refrigeration oil.

In view of the above circumstances, the object of the present invention is to provide an air conditioner equipped with multiple outdoor units that can select between a cooling/heating switching system and a cooling/heating free system, in which all outdoor units can be unified into either the cooling/heating switching system or the cooling/heating free system.

An air-conditioning apparatus according to one aspect of the present invention includes a plurality of outdoor units, a plurality of indoor units, and a plurality of connection pipes connecting each of the indoor units in parallel to the plurality of outdoor units, and is capable of selecting either a first refrigerant circuit state in which each of the indoor units can individually perform a cooling operation or a heating operation, or a second refrigerant circuit state in which each of the indoor units can simultaneously perform a cooling operation or a heating operation,
each of the outdoor units has a communication unit that communicates with each other and a refrigerant circuit selection unit that selects either the first refrigerant circuit state or the second refrigerant circuit state;
When either the first refrigerant circuit state or the second refrigerant circuit state is selected in one of the plurality of outdoor units, a state signal including information on the selected refrigerant circuit state is transmitted from a communication unit of the one outdoor unit to a communication unit of the other outdoor units,
The other outdoor units that have received the state signal select the same refrigerant circuit state as the refrigerant circuit state selected by the one outdoor unit.

The refrigerant circuit selection unit is a switching operation unit that selects either the first refrigerant circuit state or the second refrigerant circuit state, and the state signal may include information regarding the refrigerant circuit state selected by the switching operation unit.

Of the multiple outdoor units, one outdoor unit may be set as a parent outdoor unit, and the other outdoor units may be set as child outdoor units that operate according to instructions from the parent outdoor unit, and the child outdoor units may select a refrigerant circuit state that is the same as the refrigerant circuit state selected by the parent outdoor unit based on the status signal transmitted from the parent outdoor unit.

Of the multiple outdoor units, one outdoor unit is set as a parent outdoor unit, and the other outdoor units are set as child outdoor units that operate according to instructions from the parent outdoor unit, and when the refrigerant circuit state selected by the switching operation unit of the child outdoor unit differs from the refrigerant circuit state included in the state signal transmitted from the parent outdoor unit, the child outdoor unit may select the refrigerant circuit state included in the state signal transmitted from the parent outdoor unit.

When the supply of power to the multiple outdoor units is started or resumed, the parent outdoor unit may check the refrigerant circuit state selected by the switching operation unit of the parent outdoor unit, and transmit the checked refrigerant circuit state to the child outdoor unit by including it in the state signal.

When the supply of power to the child outdoor unit is started or resumed, the parent outdoor unit may include the refrigerant circuit state selected by the parent outdoor unit in the state signal and transmit it to the child outdoor unit.

The outdoor units each have a compressor, an outdoor heat exchanger, a first flow path switching means, and a second flow path switching means, and one of the refrigerant inlets and outlets of the outdoor heat exchanger may be selectively connected to the refrigerant suction pipe or the refrigerant discharge pipe of the compressor via the first flow path switching means. In the first refrigerant circuit state, three connecting pipes are used as the multiple connecting pipes: a first gas pipe and a second gas pipe selectively connected to the refrigerant suction pipe or the refrigerant discharge pipe via the second flow path switching means, and a liquid pipe connected to the other refrigerant inlet and outlet of the outdoor heat exchanger. In the second refrigerant circuit state, two connecting pipes, the first gas pipe and the liquid pipe, may be used as the multiple connecting pipes.

According to the present invention, in an air conditioning system equipped with multiple outdoor units that can select between a cooling/heating switching system and a cooling/heating free system, it is possible to reliably standardize all outdoor units to the cooling/heating switching system or the cooling/heating free system.

FIG. 1 is a refrigerant circuit diagram showing a free-heating and cooling type air conditioner. FIG. 1 is a refrigerant circuit diagram showing a cooling/heating switching type air conditioner. FIG. 2 is a block diagram showing the configuration of a control device. 1 is a refrigerant circuit diagram showing a state in which a cooling/heating free type air conditioner is mixed with an outdoor unit of a cooling/heating switching type. 1 is a refrigerant circuit diagram showing a state in which a cooling/heating free type outdoor unit is mixed in an air conditioning apparatus using a cooling/heating switching type. 5 is a flowchart showing an example of a control procedure for each outdoor unit. 5 is a flowchart showing an example of a control procedure for each outdoor unit when power is restored. 10 is a flowchart showing another example of the control procedure for each outdoor unit when power is restored. FIG. 11 is a refrigerant circuit diagram showing a modified example of the outdoor unit.

The following describes an embodiment of the present invention with reference to the drawings.

The air conditioning system of this embodiment is equipped with multiple outdoor units and multiple indoor units, and can select between an operating mode in which all indoor units perform either cooling or heating (switchable cooling/heating mode), and an operating mode that allows each indoor unit to selectively perform either cooling or heating (free cooling/heating mode).

Figure 1 is a refrigerant circuit diagram showing an example of the configuration of an air conditioner 10 with a free-heating and cooling system, and Figure 2 is a refrigerant circuit diagram showing an example of the configuration of an air conditioner 20 with a switching cooling and heating system. In this embodiment, an air conditioner in which three indoor units 8a, 8b, and 8c are connected in parallel to two outdoor units 2a and 2b will be described as an example.

Comparing the free-heating/cooling system air conditioner 10 and the switching-heating system air conditioner 20, the outdoor units 2a, 2b and indoor units 8a-8c are the same, but the number of connecting pipes (high-pressure gas pipe 30, low-pressure gas pipe 31, liquid pipe 32) connecting the outdoor units 2a, 2b and the indoor units 8a-8c is different. Each system of air conditioners 10 and 20 will be explained below.

[Free-heating and cooling air conditioner]
First, with reference to FIG. 1, a configuration and an example of operation of an air conditioner 10 of a cooling/heating free type will be described.

As shown in FIG. 1, the air conditioner 10 includes two outdoor units 2a and 2b, three indoor units 8a, 8b, and 8c, three diverter units 6a, 6b, and 6c, and branching devices 70, 71, and 72. The outdoor units 2a and 2b, the indoor units 8a-8c, the diverter units 6a-6c, and the branching devices 70-72 are interconnected by a high-pressure gas pipe 30 (first gas pipe), high-pressure gas branching pipes 30a and 30b, a low-pressure gas pipe 31 (second gas pipe), low-pressure gas branching pipes 31a and 31b, a liquid pipe 32, and liquid branching pipes 32a and 32b, thereby forming a refrigerant circuit of the air conditioner 10.

Depending on the open/closed state of the various valves provided in the outdoor units 2a, 2b and the distribution units 6a-6c, this air conditioning device 10 can perform a variety of operations, including heating operation (all indoor units are in heating operation), heating-dominated operation (when the total capacity required by indoor units performing heating operation exceeds the total capacity required by indoor units performing cooling operation), cooling operation (all indoor units are in cooling operation), and cooling-dominated operation (when the total capacity required by indoor units performing cooling operation exceeds the total capacity required by indoor units performing heating operation).

(Outdoor unit)
The outdoor units 2a and 2b have the same configuration, and corresponding parts are denoted by the same reference numerals. In the following description, only the configuration of the outdoor unit 2a will be described, and a description of the outdoor unit 2b will be omitted.

The outdoor unit 2a includes a compressor 21, a first three-way valve 22 and a second three-way valve 23 which are first flow path switching means, a first outdoor heat exchanger 24, a second outdoor heat exchanger 25, an outdoor fan 26, an accumulator 27, a four-way valve 29 which is a second flow path switching means, a first outdoor expansion valve 40 connected to the first outdoor heat exchanger 24, and a second outdoor expansion valve 41 connected to the second outdoor heat exchanger 25.

The compressor 21 is a variable capacity compressor whose operating capacity can be varied by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. The discharge side of the compressor 21 is connected to the port a of the first three-way valve 22 and the port d of the second three-way valve 23 by the discharge pipe 28, and is connected to the port g of the four-way valve 29 by the discharge pipe 28 and the outdoor unit high pressure gas pipe 33. The discharge pipe 28 is a refrigerant pipe connecting the discharge side of the compressor 21 to the connection point A, and the outdoor unit high pressure gas pipe 33 is a refrigerant pipe connecting the connection point A to the stop valve 44. The suction side of the compressor 21 is connected to the outflow side of the accumulator 27 by the suction pipe 42, and the inflow side of the accumulator 27 is connected to the stop valve 45 by the outdoor unit low pressure gas pipe 34.

The first three-way valve 22 and the second three-way valve 23 are valves for switching the direction of refrigerant flow in the refrigerant circuit. The first three-way valve 22 has three ports a, b, and c, and the second three-way valve 23 has three ports d, e, and f. In the first three-way valve 22, the refrigerant piping connected to port a is connected to the discharge piping 28 and the outdoor unit high-pressure gas pipe 33 at connection point A. In addition, port b is connected to one end (one of the refrigerant inlet and outlet ports) of the first outdoor heat exchanger 24 by a refrigerant piping, and the refrigerant piping connected to port c is connected to the outdoor unit low-pressure gas pipe 34 at connection point D.

In the second three-way valve 23, the refrigerant pipe connected to port d is connected at connection point A to the discharge pipe 28 and the refrigerant pipe connected to the outdoor unit high-pressure gas pipe 33. Port e is also connected to one end (one refrigerant inlet/outlet) of the second outdoor heat exchanger 25 by a refrigerant pipe, and the refrigerant pipe connected to port f is connected at connection point C to the refrigerant pipe connected to port c of the first three-way valve 22.

The four-way valve 29 is a valve whose control mode changes depending on whether the outdoor units 2a and 2b are set to the cooling/heating free mode or the cooling/heating switching mode, and has four ports g, h, k, and m. As described above, port g is connected to the outdoor unit high-pressure gas pipe 33, and port h is connected to the stop valve 44. Port k is closed, and port m is connected to the connection point E in the outdoor unit low-pressure gas pipe 34 by a refrigerant pipe. As will be described in detail later, when the outdoor units 2a and 2b are set to the cooling/heating free mode, the four-way valve 29 is switched so that the refrigerant flows from the outdoor unit high-pressure gas pipe 33 to the high-pressure gas distribution pipe 30a and the high-pressure gas distribution pipe 30b. In addition, when the outdoor units 2a and 2b are set to the cooling/heating switching system, the four-way valve 29 is switched so that the refrigerant flows from the outdoor unit high-pressure gas pipe 33 to the high-pressure gas distribution pipe 30a and the high-pressure gas distribution pipe 30b during heating operation, and the four-way valve 29 is switched so that the refrigerant flows from the low-pressure gas distribution pipe 31a and the low-pressure gas distribution pipe 31b to the outdoor unit low-pressure gas pipe 34 during cooling operation.

One end (one refrigerant inlet/outlet) of the first outdoor heat exchanger 24 is connected to port b of the first three-way valve 22 via a refrigerant pipe as described above, and the other end (the other refrigerant inlet/outlet) is connected to one port of the first outdoor expansion valve 40 via a refrigerant pipe. The other port of the first outdoor expansion valve 40 is connected to the stop valve 46 and the outdoor unit liquid pipe 35. Also, one end (one refrigerant inlet/outlet) of the second outdoor heat exchanger 25 is connected to port e of the second three-way valve 23 via a refrigerant pipe as described above, and the other end (the other refrigerant inlet/outlet) is connected to one port of the second outdoor expansion valve 41 via a refrigerant pipe. The other port of the second outdoor expansion valve 41 is connected to the connection point B in the outdoor unit liquid pipe 35 by a refrigerant pipe.

The inlet side of the accumulator 27 is connected to the outdoor unit low pressure gas pipe 34, and the outlet side is connected to the suction side of the compressor 21 via the suction pipe 42. The accumulator 27 separates the inflowing refrigerant into gas refrigerant and liquid refrigerant, and only the gas refrigerant is sucked into the compressor 21a. The outdoor fan 26 is rotated by a fan motor (not shown) to take in outside air into the outdoor unit 2a, exchange heat between the refrigerant and the outside air in the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25, and then releases the heat-exchanged outside air to the outside of the outdoor unit 2a.

In addition to the configuration described above, the outdoor unit 2a is provided with various sensors. As shown in FIG. 1, the discharge pipe 28 is provided with a high-pressure sensor 50 that detects the pressure of the refrigerant discharged from the compressor 21, and a discharge temperature sensor 53 that detects the temperature of the refrigerant discharged from the compressor 21. In addition, between the connection point D in the outdoor unit low-pressure gas pipe 34 and the inlet side of the accumulator 27a, a low-pressure sensor 51 that detects the pressure of the refrigerant sucked into the compressor 21, and an intake temperature sensor 54 that detects the temperature of the refrigerant sucked into the compressor 21 are provided.

The refrigerant piping connecting the port b of the first three-way valve 22 and the first outdoor heat exchanger 24 is provided with a first heat exchanger temperature sensor 56 that detects the temperature of the refrigerant flowing out of or into the first outdoor heat exchanger 24. In addition, the refrigerant piping connecting the port e of the second three-way valve 23 and the second outdoor heat exchanger 25 is provided with a second heat exchanger temperature sensor 57 that detects the temperature of the refrigerant flowing out of or into the second outdoor heat exchanger 25. In addition, an outdoor air temperature sensor 58 is provided that detects the temperature of the outdoor air flowing into the outdoor unit 2a, i.e., the outdoor air temperature.

(Indoor unit)
The three indoor units 8a to 8c each include an indoor heat exchanger 81, an indoor expansion valve 82, and an indoor fan 83. Since the indoor units 8a to 8c all have the same configuration, the following description will only cover the configuration of the indoor unit 8a, and descriptions of the other indoor units 8b and 8c will be omitted.

One end (one refrigerant inlet/outlet) of the indoor heat exchanger 81 is connected to one port of the indoor expansion valve 82 by a refrigerant pipe, and the other end (the other refrigerant inlet/outlet) is connected to the diversion unit 6a (described later) by a refrigerant pipe 87. The indoor heat exchanger 81 functions as an evaporator when the indoor unit 8a performs cooling operation, and functions as a condenser when the indoor unit 8a performs heating operation.

One port of the indoor expansion valve 82 is connected to the indoor heat exchanger 81 as described above, and the other port is connected to the liquid pipe 32. When the indoor heat exchanger 81 functions as an evaporator, the opening degree of the indoor expansion valve 82 is adjusted according to the required cooling capacity, and when the indoor heat exchanger 81 functions as a condenser, the opening degree of the indoor expansion valve 82 is adjusted according to the required heating capacity.

The indoor fan 83 is rotated by a fan motor (not shown) to draw indoor air into the indoor unit 8a, exchange heat between the refrigerant and the indoor air in the indoor heat exchanger 81, and then supply the heat-exchanged air to the room.

In addition to the configuration described above, the indoor unit 8a is provided with various sensors. The refrigerant piping on the indoor expansion valve 82 side of the indoor heat exchanger 81 is provided with a refrigerant temperature sensor 84 that detects the temperature of the refrigerant, and the refrigerant piping on the diversion unit 6a side of the indoor heat exchanger 81 is provided with a refrigerant temperature sensor 85 that detects the temperature of the refrigerant. In addition, near the indoor air intake port (not shown) of the indoor unit 8a, a room temperature sensor 86 that detects the temperature of the indoor air flowing into the indoor unit 8a, i.e., the indoor temperature, is provided.

(Diversion unit)
The air conditioning apparatus 10 is equipped with three diverter units 6a to 6c corresponding to the three indoor units 8a to 8c. The diverter units 6a to 6c each include first solenoid valves 61a to 61c, second solenoid valves 62a to 62c, first diverter pipes 63a to 63c, and second diverter pipes 64a to 64c. Since the diverter units 6a to 6c all have the same configuration, the following description will only cover the configuration of the diverter unit 6a, and will omit descriptions of the other diverter units 6b and 6c.

One end of the first branch pipe 63a is connected to the high-pressure gas pipe 30, and one end of the second branch pipe 64a is connected to the low-pressure gas pipe 31. The other end of the first branch pipe 63a and the other end of the second branch pipe 64a are connected to each other, and this connection is connected to the indoor heat exchanger 81 by a refrigerant pipe 87. The first branch pipe 63a is provided with a first solenoid valve 61a, and the second branch pipe 64a is provided with a second solenoid valve 62a. By opening and closing the first solenoid valve 61a and the second solenoid valve 62a, respectively, the flow path of the refrigerant in the refrigerant circuit can be switched so that the indoor heat exchanger 81 of the indoor unit 8a corresponding to the branch unit 6a is connected to the discharge side (high-pressure gas pipe 30 side) or the suction side (low-pressure gas pipe 31 side) of the compressor 21.

(Connection piping)
The connection state of the outdoor units 2a, 2b, indoor units 8a to 8c, and distribution units 6a to 6c described above with the high pressure gas pipe 30, high pressure gas branch pipes 30a, 30b, low pressure gas pipe 31, low pressure gas branch pipes 31a, 31b, liquid pipe 32, liquid branch pipes 32a, 32b, and branchers 70, 71, 72 will be described using Figure 1.

One end of the high-pressure gas distribution pipes 30a, 30b is connected to the shutoff valve 44 of each outdoor unit 2a, 2b, and the other end of the high-pressure gas distribution pipes 30a, 30b is connected to a branching device 70. One end of the high-pressure gas pipe 30 is connected to this branching device 70, and the other end of the high-pressure gas pipe 30 branches and is connected to the first branching pipes 63a-63c of the branching units 6a-6c.

One end of the low-pressure gas branch pipes 31a, 31b is connected to the shutoff valve 45 of each outdoor unit 2a, 2b, and the other end of the low-pressure gas branch pipes 31a, 31b is connected to a branching device 71. One end of the low-pressure gas pipe 31 is connected to this branching device 71, and the other end of the low-pressure gas pipe 31 branches and is connected to the second branch pipes 64a-64c of the branching units 6a-6c.

One end of the liquid distribution pipes 32a, 32b is connected to the shutoff valve 46 of each outdoor unit 2a, 2b, and the other end of the liquid distribution pipes 32a, 32b is connected to a branching device 72. One end of the liquid pipe 32 is connected to this branching device 72, and the other end of the liquid pipe 32 branches and is connected to the indoor expansion valves 82 of the indoor units 8a to 8c by refrigerant piping.

The indoor heat exchanger 81 of each indoor unit 8a to 8c is connected to the connection point between the first branch pipe 63a to 63c and the second branch pipe 64a to 64c in each branch unit 6a to 6c by a refrigerant pipe 87.

The above-described connections form the refrigerant circuit of the air conditioning device 10, and a refrigeration cycle is established by flowing refrigerant through the refrigerant circuit. In the following description, the state of the refrigerant circuit in which each of the indoor units 8a to 8c can individually perform cooling or heating operation as shown in Figure 1 is also referred to as the "first refrigerant circuit state."

(Control device)
The outdoor units 2a and 2b are provided with control devices 110a and 110b, respectively. Fig. 3 is a block diagram showing the configurations of the control devices 110a and 110b. Since the configurations of the control devices 110a and 110b are basically the same, the following description will only cover the configuration of the control device 110a, and will omit a description of the control device 110b.

The control device 110a is mounted on a control board (not shown) stored in an electrical equipment box (not shown), and includes a CPU 111a, a memory unit 112a, a refrigerant circuit selection unit 113a, and a communication unit 114a. The CPU 111a receives detection signals from the above-mentioned sensors of the outdoor unit 2a, and receives control signals output from the indoor units 8a to 8c via the communication unit 113a. Based on the received detection signals and control signals, the CPU 111a performs various controls, such as drive control of the compressor 21, switching control of the first three-way valve 22, the second three-way valve 23, and the four-way valve 29, and opening control of the first outdoor expansion valve 40 and the second outdoor expansion valve 41. The opening and closing control of the first solenoid valves 61a to 61c and the second solenoid valves 62a to 62c in the diversion units 6a to 6c is performed by a control device (not shown) of the indoor units 6a to 6c corresponding to the diversion units 6a to 6c.

The memory unit 112a is composed of ROM and RAM, and stores the control program for the outdoor unit 2a and detection values corresponding to detection signals from each sensor. The memory unit 112a stores a control program for executing the cooling/heating free operation mode and a control program for executing the cooling/heating switching operation mode (FIG. 2) described below.

The refrigerant circuit selection unit 113a is for selecting either the cooling/heating free mode or the cooling/heating switching mode of the outdoor unit 2a. When the cooling/heating free mode is selected by the refrigerant circuit selection unit 113a, the CPU 111a sets the refrigerant circuit state to the first refrigerant circuit state and executes a control program for the cooling/heating free mode operation mode, and when the cooling/heating switching mode is selected by the refrigerant circuit selection unit 113a, the CPU 111a sets the refrigerant circuit state to the second refrigerant circuit state and executes a control program for the cooling/heating switching mode operation mode.

In this embodiment, the refrigerant circuit selection unit 113a is a hard switch (switching operation unit) such as a dip switch or toggle switch that is housed in the electrical equipment box and is switched by an operator. Alternatively, the refrigerant circuit selection unit 113a may be a soft switch that is switched by an input signal from an electronic device such as a PC. Note that the refrigerant circuit state may be switched by the CPU 111a upon receiving an instruction from another outdoor unit (in this embodiment, outdoor unit 2b) (details will be described later).

The communication unit 114a is an interface that performs communication between the outdoor unit 2a and the indoor units 8a to 8c, and between the outdoor unit 2a and the outdoor unit 2b (communication unit 114b), and is equipped with, for example, a short-range wireless communication module.

As described above, the configuration of the control device 110b is the same as that of the control device 110a, and the components of the control device 110a are numbers that have the suffix a changed to b, which corresponds to the components of the control device 110a.

Next, the operation of the free-heating and cooling air conditioner 10 will be explained using Figure 1.

(Full heating operation)
As shown in Fig. 1, when all the indoor units 8a to 8c are performing heating operation, the first three-way valve 22 of each of the outdoor units 2a and 2b is switched so that port b communicates with port c (shown by solid lines in Fig. 1), causing the first outdoor heat exchanger 24 to function as an evaporator, and the second three-way valve 23 of each of the outdoor units 2a and 2b is switched so that port e communicates with port f (shown by solid lines in Fig. 1), causing the second outdoor heat exchanger 25 to function as an evaporator. Also, the four-way valve 29 of each of the outdoor units 2a and 2b is switched so that port g communicates with port h and port k communicates with port m (shown by solid lines in Fig. 1).

In the indoor units 8a to 8c, the first solenoid valves 61a to 61c of the corresponding diversion units 6a to 6c are opened to allow the refrigerant to flow through the first diversion pipes 63a to 63c, and the second solenoid valves 62a to 62c are closed to block the second diversion pipes 64a to 64c. As a result, the indoor heat exchangers 81 of the indoor units 8a to 8c all function as condensers.

The high-pressure refrigerant discharged from the compressor 21 of the outdoor unit 2a flows through the discharge pipe 28 and the outdoor unit high-pressure gas pipe 33, and enters the high-pressure gas branch pipe 30a via the shutoff valve 44. Similarly, the high-pressure refrigerant discharged from the compressor 21 of the outdoor unit 2b flows through the outdoor unit high-pressure gas pipe 33 via the discharge pipe 28, and enters the high-pressure gas branch pipe 30b via the shutoff valve 44. The high-pressure refrigerant that has entered the high-pressure gas branch pipes 30a and 30b joins at the branching device 70 and flows through the high-pressure gas pipe 30, and then branches from the high-pressure gas pipe 30 and enters the branching units 6a to 6c.

The high-pressure refrigerant that flows into the diversion units 6a to 6c flows through the first diversion pipes 63a to 63c equipped with the first solenoid valves 61a to 61c that are open, flows out of the diversion units 6a to 6c, and flows into the indoor units 8a to 8c that correspond to the diversion units 6a to 6c.

The high-pressure refrigerant that flows into each indoor unit 8a to 8c flows into the indoor heat exchanger 81 and exchanges heat with the indoor air to condense. This warms the indoor air, heating the room in which the indoor units 8a to 8c are installed. The high-pressure refrigerant that flows out of the indoor heat exchanger 81 passes through the indoor expansion valve 82 and is reduced in pressure. The opening degree of the indoor expansion valve 82 is determined according to the degree of subcooling of the refrigerant at the refrigerant outlet of the indoor heat exchanger 81. The degree of subcooling of the refrigerant can be calculated, for example, by subtracting the refrigerant temperature at the refrigerant outlet of the indoor heat exchanger 81 detected by the refrigerant temperature sensor 84 from the high-pressure saturation temperature (corresponding to the condensation temperature in the indoor heat exchanger 81) calculated from the pressure detected by the high-pressure sensor 50 of the outdoor units 2a and 2b.

The intermediate pressure refrigerant flowing out of each indoor unit 8a to 8c flows into the liquid pipe 32, where it joins and flows into the branching device 72. The intermediate pressure refrigerant that is branched from the branching device 72 to the liquid branching pipes 32a and 32b flows into each outdoor unit 2a and 2b via the closing valve 46. The intermediate pressure refrigerant that flows into each outdoor unit 2a and 2b flows through the outdoor unit liquid pipe 35, branches at connection point B, and passes through the first outdoor expansion valve 40a and the second outdoor expansion valve 41 to be reduced in pressure and become a low pressure refrigerant.

The opening degree of the first outdoor expansion valve 40 is determined according to the degree of superheat of the refrigerant at the refrigerant outlet of the first outdoor heat exchanger 24. The opening degree of the second outdoor expansion valve 41 is determined according to the degree of superheat of the refrigerant at the refrigerant outlet of the second outdoor heat exchanger 25. The degree of superheat of the refrigerant is obtained, for example, by subtracting the low-pressure saturation temperature (corresponding to the evaporation temperature in the first outdoor heat exchanger 24 or the second outdoor heat exchanger 25) calculated from the pressure detected by the low-pressure sensor 51 of the outdoor units 2a and 2b from the refrigerant temperature at the refrigerant outlet of the first outdoor heat exchanger 24 or the second outdoor heat exchanger 25 detected by the first heat exchanger temperature sensor 56 or the second heat exchanger temperature sensor 57.

The low-pressure refrigerant decompressed by the first outdoor expansion valve 40 and the second outdoor expansion valve 41 flows into the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25, where it exchanges heat with the outside air and evaporates. The low-pressure refrigerant flowing out of the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 merges at connection point C via the first three-way valve 22 and the second three-way valve 23, and is sucked into the compressor 21 via connection point D and the accumulator 27, where it is compressed again.

(Fully cooling operation)
Next, a case where all the indoor units 8a to 8c perform cooling operation will be described. When all the indoor units 8a to 8c perform cooling operation, the first three-way valve 22 of each outdoor unit 2a, 2b is switched so that port a communicates with port b (shown by dashed lines in FIG. 1), so that the first outdoor heat exchanger 24 functions as a condenser, and the second three-way valve 23 is switched so that port d communicates with port e (shown by dashed lines in FIG. 1), so that the second outdoor heat exchanger 25 functions as a condenser. In addition, the four-way valve 29 of each outdoor unit 2a, 2b is switched so that port g communicates with port h and port k communicates with port m (shown by solid lines in FIG. 1).

In the indoor units 8a to 8c, the first solenoid valves 61a to 61c of the corresponding diversion units 6a to 6c are closed to block the first diversion pipes 63a to 63c, and the second solenoid valves 62a to 62c are opened to allow the refrigerant to flow through the second diversion pipes 64a to 64c. As a result, the indoor heat exchangers 81 of the indoor units 8a to 8c all function as evaporators.

The high-pressure refrigerant discharged from the compressor 21 of each outdoor unit 2a, 2b is divided into the first three-way valve 22, the second three-way valve 23 side, and the high-pressure gas pipe 30 side. The refrigerant flowing through the first three-way valve 22 and the second three-way valve 23 side flows into the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25, and condenses by exchanging heat with the outside air. The refrigerant flowing to the high-pressure gas pipe 30 side does not flow into the indoor units 8a to 8c, but remains in the outdoor unit high-pressure gas pipe 33, the high-pressure gas distribution pipes 30a, 30b, and the high-pressure gas pipe 30, because the first solenoid valves 61a to 61c of each distribution unit 6a to 6c are closed.

Here, when the cooling capacity required by each indoor unit 8a to 8c exceeds a predetermined value, if refrigerant stagnates in the outdoor unit high-pressure gas pipe 33 and the high-pressure gas pipe 30 as described above, there is a risk that the amount of refrigerant required to achieve the required cooling capacity cannot be circulated in the refrigerant circuit. In such a case, the four-way valve 29 is switched so that port g communicates with port k and port h communicates with port m (shown by dashed lines in FIG. 1). As a result, refrigerant only stagnates in the outdoor unit high-pressure gas pipe 33 (it does not stagnate in the high-pressure gas distribution pipes 30a, 30b and the high-pressure gas pipe 30), so the amount of refrigerant stagnates decreases and the amount of refrigerant circulating in the refrigerant circuit increases. In addition, when the cooling capacity required by each indoor unit a to 8c during full cooling operation is equal to or greater than a predetermined value, the four-way valve 29 may be switched from the state shown by the solid line in FIG. 1 to the state shown by the dashed line, and may be switched from the state shown by the solid line in FIG. 1 to the state shown by the dashed line if the cooling capacity required by each indoor unit a to 8c at the start of full cooling operation is equal to or greater than a predetermined value.

The refrigerant condensed in the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 of the outdoor unit 2a passes through the first outdoor expansion valve 40 and the second outdoor expansion valve 41, which are fully opened by the control device 110a, and flows into the liquid distribution pipe 32a through the stop valve 46. Similarly, the refrigerant condensed in the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 of the outdoor unit 2b passes through the first outdoor expansion valve 40 and the second outdoor expansion valve 41, which are fully opened by the control device 110b, and flows into the liquid distribution pipe 32b through the stop valve 46. The intermediate pressure refrigerant that flows into the liquid distribution pipes 32a and 32b joins at the branch 72 and flows through the liquid pipe 32, and from the liquid pipe 32, it is divided and flows into each indoor unit 8a to 8c.

The intermediate pressure refrigerant that flows into each indoor unit 8a to 8c is decompressed by the indoor expansion valve 82 to become a low pressure refrigerant, which flows into the indoor heat exchanger 81. The low pressure refrigerant that flows into the indoor heat exchanger 81 exchanges heat with the indoor air and evaporates, thereby cooling the room in which the indoor units 8a to 8c are installed. Here, the indoor expansion valve 82 determines the degree of refrigerant superheat at the outlet of the indoor heat exchanger 81, which serves as an evaporator, from the refrigerant temperature detected by the refrigerant temperature sensors 84 and 85, and determines the opening degree accordingly.

The low-pressure refrigerant flowing out from the indoor heat exchanger 81 flows into the branching units 6a-6e, and flows through the second branching pipes 64a-64b equipped with the open second solenoid valves 62a-62c, and into the low-pressure gas pipe 31. The low-pressure refrigerant that flows into the low-pressure gas pipe 31 from each branching unit 6a-6c and merges inside the low-pressure gas pipe 31 is divided into the low-pressure gas branch pipes 31a, 31b by the branching pipe 71 and flows into each outdoor unit 2a, 2b. The low-pressure refrigerant that flows into each outdoor unit 2a, 2b passes through the outdoor unit low-pressure gas pipe 34, is sucked into the compressor 21 via the accumulator 27, and is compressed again.

[Operation of air conditioner when indoor units perform both cooling and heating operations]
Next, a case where the indoor units 8a to 8c are performing both cooling and heating operations will be described. When the indoor units 8a to 8c are performing both cooling and heating operations, the state of the refrigerant circuit is determined according to the comparison result between the total cooling capacity required by the indoor units performing cooling operation and the total heating capacity required by the indoor units performing heating operation. As an example, in this embodiment, when the indoor units 8a, 8b are in heating operation and the indoor unit 8c is in cooling operation, and the heating capacity required by the two indoor units 8a, 8b performing heating operation is greater than the cooling capacity required by the one indoor unit 8c performing cooling operation, a heating-dominant operation is performed in which the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 each function as an evaporator, and when the indoor units 8a, 8b are in cooling operation and the indoor unit 8c is in heating operation, and the cooling capacity required by the two indoor units 8a, 8b performing cooling operation is greater than the heating capacity required by the one indoor unit 8c performing heating operation, a cooling-dominant operation is performed in which the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 each function as a condenser.

(Heating-dominant operation)
In the heating-dominant operation, in each of the outdoor units 2a, 2b, the first three-way valve 22 is switched so that port b communicates with port c (shown by a solid line in FIG. 1), and the second three-way valve 23 is switched so that port e communicates with port f (shown by a solid line in FIG. 1). Also, the four-way valve 29 is switched so that port g communicates with port h and port k communicates with port m (shown by a solid line in FIG. 1). As a result, the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 both function as evaporators.

The first solenoid valves 61a, 61b of the two diversion units 6a, 6b corresponding to the two indoor units 8a, 8b performing heating operation are opened to connect the first diversion pipes 63a, 63b, and the second solenoid valves 62a, 62b are closed to block the second diversion pipes 64a, 64b. As a result, the indoor heat exchangers 81 of the two indoor units 8a, 8b become condensers.

Meanwhile, the first solenoid valve 61c of the diversion unit 6c corresponding to the indoor unit 8c performing cooling operation closes to block the first diversion pipe 63c, and the second solenoid valve 62c opens to connect the second diversion pipe 64c. This causes the indoor heat exchanger 81 of the indoor unit 8c to function as an evaporator.

The high-pressure refrigerant discharged from the compressor 21 of each outdoor unit 2a, 2b flows through the high-pressure gas pipe 30 and is divided into the diversion units 6a, 6b. The high-pressure refrigerant that flows into the diversion units 6a, 6b flows through the first diversion pipes 63a, 63b equipped with the first solenoid valves 61a, 61b that are open, flows out of the diversion units 6a, 6b, and flows into the corresponding indoor units 8a, 8b.

The high-pressure refrigerant that flows into the indoor units 8a and 8b flows into the indoor heat exchanger 81 and exchanges heat with the indoor air to condense, thereby heating the room in which the indoor units 8a and 8b are installed. The high-pressure refrigerant that condenses in the indoor heat exchanger 81 passes through the indoor expansion valve 82 and is reduced in pressure to become an intermediate-pressure refrigerant. Here, the control unit of the indoor units 8a and 8b determines the degree of refrigerant subcooling in the indoor heat exchanger 81, which is a condenser, from the refrigerant temperature detected by the refrigerant temperature sensor 84 and the high-pressure saturation temperature obtained from the outdoor units 2a and 2b, and the opening degree of the indoor expansion valve 82 is determined accordingly.

The intermediate pressure refrigerant flowing out of the indoor units 8a and 8b flows into the liquid pipe 32. Then, part of the intermediate pressure refrigerant that joins in the liquid pipe 32 flows into the outdoor units 2a and 2b through the branch pipe 72 and the liquid branch pipes 32a and 32b, and the rest flows through the liquid pipe 32 and into the indoor unit 8c.

The intermediate pressure refrigerant that flows into the outdoor units 2a and 2b is reduced in pressure as it passes through the first outdoor expansion valve 40 and the second outdoor expansion valve 41, the opening of which corresponds to the degree of superheat of the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25, and becomes a low pressure refrigerant, and flows into the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25. The low pressure refrigerant that flows into the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 exchanges heat with the outside air and evaporates. The low pressure refrigerant that flows out of the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 passes through the first three-way valve 22 and the second three-way valve 23, then passes through the accumulator 27, is sucked into the compressor 21, and is compressed again.

Meanwhile, the intermediate pressure refrigerant that flows into the indoor unit 8c is decompressed by the indoor expansion valve 82 to become a low pressure refrigerant, which flows into the indoor heat exchanger 81. The low pressure refrigerant that flows into the indoor heat exchanger 81 exchanges heat with the indoor air and evaporates, thereby cooling the room in which the indoor unit 8c is installed. Here, the indoor expansion valve 82 of the indoor unit 8c determines the degree of refrigerant superheat in the indoor heat exchanger 81, which is an evaporator, from the refrigerant temperature detected by the refrigerant temperature sensors 84, 85, and determines the opening degree accordingly.

The low-pressure refrigerant flowing out of the indoor heat exchanger 8c flows into the branch unit 6c, flows through the second branch pipe 64c equipped with the open second solenoid valve 62c, and flows into the low-pressure gas pipe 31. The low-pressure refrigerant that flows into the low-pressure gas pipe 31 flows into the outdoor units 2a and 2b through the branch pipe 71 and the low-pressure gas branch pipes 31a and 31b, passes through the accumulator 27, and is sucked into the compressor 21 and compressed again.

(Cooling-dominant operation)
In cooling-dominated operation, in each of the outdoor units 2a, 2b, the first three-way valve 22 is switched so that port a communicates with port b (shown by a dashed line in FIG. 1), and the second three-way valve 23 is switched so that port d communicates with port e (shown by a dashed line in FIG. 1). Also, the four-way valve 29 is switched so that port g communicates with port h and port k communicates with port m (shown by a solid line in FIG. 1). As a result, the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 both function as condensers.

In addition, the solenoid valves 61a and 61b of the two diversion units 6a and 6b corresponding to the two indoor units 8a and 8b performing cooling operation are closed to block the first diversion pipes 63a and 63b, and the second solenoid valves 62a and 62b are opened to connect the second diversion pipes 64a and 64b. As a result, the indoor heat exchangers 81 of the two indoor units 8a and 8b become evaporators.

On the other hand, the solenoid valve 61c of the diversion unit 6c corresponding to the indoor unit 8c performing heating operation opens to connect the first diversion pipe 63c, and the second solenoid valve 62c closes to block the second diversion pipe 64c. This causes the indoor heat exchanger 81 of the indoor unit 8c to function as a condenser.

The high-pressure refrigerant discharged from the compressor 21 of each outdoor unit 2a, 2b is divided into the first three-way valve 22, the second three-way valve 23 side, and the high-pressure gas pipe 30 side. The high-pressure refrigerant that has passed through the first three-way valve 22 and the second three-way valve 23 flows into the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25, where it exchanges heat with the outside air and condenses. The refrigerant condensed in the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 passes through the first outdoor expansion valve 40 and the second outdoor expansion valve 41, whose opening is set by the control devices 110a, 110b according to the difference between the discharge pressure of the compressor 21 that has been taken in and the liquid pressure, and becomes an intermediate-pressure refrigerant, flows through the liquid pipe 32, and is divided and flows into the indoor units 8a, 8b.

The intermediate pressure refrigerant that flows into the indoor units 8a and 8b is decompressed by the indoor expansion valve 82 to become a low pressure refrigerant, which flows into the indoor heat exchanger 81. The low pressure refrigerant that flows into the indoor heat exchanger 81 exchanges heat with the indoor air and evaporates, thereby cooling the room in which the indoor units 8a and 8b are installed. Here, the indoor expansion valve 82 determines the degree of refrigerant superheat in the indoor heat exchanger 81, which is an evaporator, from the refrigerant temperature detected by the refrigerant temperature sensors 84 and 85, and the opening degree is determined accordingly.

The low-pressure refrigerant flowing out from the indoor heat exchanger 81 of the indoor units 8a and 8b flows into the branching units 6a and 6b, and flows through the second branching pipes 64a and 64b equipped with the second solenoid valves 62a and 62b that are open, and into the low-pressure gas pipe 31. The low-pressure refrigerant that flows into the low-pressure gas pipe 31 from each branching unit 6a and 6b merges in the low-pressure gas pipe 31, then flows into the outdoor units 2a and 2b through the branching pipe 71 and the low-pressure gas branching pipes 31a and 31b, passes through the accumulator 27, and is sucked into the compressor 21 and compressed again.

On the other hand, the high-pressure refrigerant that flows through the high-pressure gas pipe 30 and into the diverter unit 6c flows through the first diverter pipe 63c equipped with the open solenoid valve 61c and flows into the indoor unit 8c. The high-pressure refrigerant that flows into the indoor unit 8c flows into the indoor heat exchanger 81 and exchanges heat with the indoor air and condenses, thereby heating the room in which the indoor unit 8c is installed. The high-pressure refrigerant that flows out of the indoor heat exchanger 81 passes through the indoor expansion valve 82 and is reduced in pressure to become an intermediate-pressure refrigerant. Here, the indoor expansion valve 82 of the indoor unit 8c calculates the degree of refrigerant subcooling in the indoor heat exchanger 81, which is a condenser, from the refrigerant temperature detected by the refrigerant temperature sensor 84 and the high-pressure saturation temperature obtained from the outdoor units 2a and 2b, and the opening degree is determined accordingly.

Then, the intermediate pressure refrigerant that flows out of the indoor unit 8c and into the liquid pipe 32 flows into the outdoor units 2a and 2b through the branch pipe 72 and the liquid branch pipes 32a and 32b. The intermediate pressure refrigerant that flows into the outdoor units 2a and 2b is reduced in pressure as it passes through the first outdoor expansion valve 40 and the second outdoor expansion valve 41, which have openings that correspond to the superheat degrees of the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25, and becomes a low pressure refrigerant, and flows into the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25. The low pressure refrigerant that flows into the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 exchanges heat with the outside air and evaporates. The low-pressure refrigerant that flows out of the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 passes through the first three-way valve 22 and the second three-way valve 23, then passes through the accumulator 27 and is sucked into the compressor 21 and compressed again.

[Air conditioner with switching between hot and cold modes]
Next, a configuration and operation example of the cooling/heating switching type air conditioner 20 will be described with reference to FIG.

As shown in FIG. 2, unlike the above-mentioned free-heating and cooling air conditioner, the cooling/heating switching air conditioner 20 does not include the diverter units 6a-6c, the low-pressure gas pipe 31, the low-pressure gas diverter pipes 31a, 31b, and the branch pipe 71. That is, in the cooling/heating switching air conditioner 20, the shut-off valves 45 of the outdoor units 2a, 2b are closed, and the outdoor units 2a, 2b and the indoor units 8a-8c are connected in parallel by two connecting pipes, the gas pipe 30 (corresponding to the high-pressure gas pipe 30 in the cooling/heating free-heating air conditioner 10) and the liquid pipe 32. The outdoor units 2a, 2b and the indoor units 8a-8c in the cooling/heating switching air conditioner 20 have the same configuration as those in the cooling/heating free-heating air conditioner 10, so their description will be omitted.

In the air conditioner 20 with the cooling/heating switching system, during heating operation, the first three-way valve 22 of each outdoor unit 2a, 2b is switched so that port b communicates with port c (shown by solid lines in FIG. 2), and the second three-way valve 23 is switched so that port e communicates with port f (shown by solid lines in FIG. 2). Then, the four-way valve 29 of each outdoor unit 2a, 2b is switched so that port g communicates with port h and port k communicates with port m (shown by solid lines in FIG. 2). This allows the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 of each outdoor unit 2a, 2b to function as evaporators, and the indoor unit 81 of each indoor unit 8a to 8c to function as a condenser.

On the other hand, in the air conditioner 20 of the cooling/heating switching system, in cooling operation, as in the case of the air conditioner 10 of the cooling/heating free system during full cooling operation, the first three-way valve 22 of each outdoor unit 2a, 2b is switched so that port a communicates with port b (shown by the dashed line in FIG. 2), and the second three-way valve 23 is switched so that port d communicates with port e (shown by the dashed line in FIG. 2). Then, the four-way valve 29 of each outdoor unit 2a, 2b is switched so that port g communicates with port k and port h communicates with port m (shown by the dashed line in FIG. 2). This allows the first outdoor heat exchanger 24 and the second outdoor heat exchanger 25 of each outdoor unit 2a, 2b to function as condensers, and the indoor unit 81 of each indoor unit 8a to 8c to function as an evaporator.

The refrigerant circuit of the air conditioning device 20 is configured as described above, and a refrigeration cycle is established by flowing refrigerant through the refrigerant circuit. In the following explanation, the state of the refrigerant circuit in which each of the indoor units 8a to 8c can simultaneously perform cooling or heating operation as shown in Figure 2 is also referred to as the "second refrigerant circuit state."

[Selection between cooling/heating switching system and cooling/heating free system]
Here, in an air conditioner having a four-way valve 29 and capable of supporting both the cooling/heating switching method and the cooling/heating free method by switching the four-way valve 29, all outdoor units must be unified into either the cooling/heating switching method or the cooling/heating free method during operation. In general, outdoor units capable of supporting both the cooling/heating switching method and the cooling/heating free method are provided with a switching means (corresponding to the refrigerant circuit selection units 113a and 113b in FIG. 3) such as a dip switch for switching the refrigerant circuit to either the cooling/heating switching method or the cooling/heating free method in each outdoor unit, and it is assumed that the switching means is operated by an operator for each outdoor unit during installation. However, due to an operation error or forgetting to operate the switching means, the air conditioner may be operated in a state where all outdoor units are not unified into either the cooling/heating switching method or the cooling/heating free method.

For example, consider a case where the outdoor unit 2a in an air conditioner that operates in the free cooling/heating mode is mistakenly switched to the cooling/heating switching mode. In this case, when performing full cooling operation, as shown in FIG. 4, the four-way valve 29 of the outdoor unit 2a is switched to a state in which port g communicates with port k and port h communicates with port m (hereinafter also referred to as the OFF state), and the four-way valve 29 of the outdoor unit 2b is switched to a state in which port g communicates with port h and port k communicates with port m (hereinafter also referred to as the ON state).

When the full cooling operation starts in this state, the refrigerant discharged from the compressor 21 of the outdoor unit 2b in which the cooling/heating free mode is selected flows into the high-pressure gas branch pipe 30b via the four-way valve 29 of the outdoor unit 2b, and after merging with the refrigerant flowing out of the indoor heat exchanger 81 of each indoor unit 8a to 8c functioning as an evaporator at the branch 70, it flows through the high-pressure gas branch pipe 30a into the outdoor unit 2a in which the cooling/heating switching mode is selected. In other words, the high-temperature and high-pressure refrigerant flowing in from the outdoor unit 2b flows into the outdoor unit low-pressure gas pipe 34 in the outdoor unit 2a and is sucked into the compressor 21 of the outdoor unit 2a. As a result, the low pressure rises in the outdoor unit 2a in which the cooling/heating switching mode is used, and the high pressure also rises accordingly, and the temperature of the refrigerant discharged from the compressor 21 may exceed the upper limit of the performance range.

In addition, in an air conditioner that operates in a cooling/heating switching system, if the outdoor unit 2b is mistakenly switched to the cooling/heating free system, the refrigerant circuit will be in the state shown in Figure 5. In this case, as in the case where the outdoor unit 2a is mistakenly switched to the cooling/heating switching system and full cooling operation is performed in an air conditioner that operates in a cooling/heating free system, the four-way valve 29 of the outdoor unit 2a is turned OFF and the four-way valve 29 of the outdoor unit 2b is turned ON, and the high-temperature, high-pressure refrigerant that has flowed in from the outdoor unit 2b flows into the outdoor unit low-pressure gas pipe 34 in the outdoor unit 2a and is sucked into the compressor 21 of the outdoor unit 2a. As a result, the low pressure rises in the outdoor unit 2a that operates in a cooling/heating switching system, and the high pressure also rises accordingly, and the temperature of the refrigerant discharged from the compressor 21 may exceed the upper limit of the operating range in terms of performance.

This problem occurs when the connections between the ports of the four-way valve 29 are different between an outdoor unit with a free cooling/heating system and an outdoor unit with a switching system, even in the same operating mode. As described above, even in the same cooling operation, the four-way valve 29 is ON in the free cooling/heating system and OFF in the switching system, resulting in a problem in which high-temperature, high-pressure refrigerant flowing out of the outdoor unit with a free cooling/heating system flows into the low-pressure side of the outdoor unit with a free cooling/heating system and the outdoor unit with a switching system.

To solve the above problems, in the air conditioning apparatus of this embodiment, when one of a plurality of outdoor units selects either the cooling/heating free mode (first refrigerant circuit state) or the cooling/heating switching mode (second refrigerant circuit state), the one outdoor unit transmits a status signal including information about the selected refrigerant circuit state to the other outdoor units. The other outdoor units that receive the status signal select the same refrigerant circuit state as the one outdoor unit, regardless of the refrigerant circuit state selected by the refrigerant circuit selection unit.

This ensures that all outdoor units are standardized to either the cooling/heating switching type or the cooling/heating free type, preventing the occurrence of problems caused by mixing outdoor units that use the cooling/heating free type and outdoor units that use the cooling/heating switching type, as described above.

[Details of this embodiment]
The details of this embodiment will be described below. In this embodiment, of the two outdoor units 2a and 2b, one outdoor unit 2a is set as a parent outdoor unit, and the other outdoor unit is set as a child outdoor unit that operates according to instructions from the parent outdoor unit. In the following description, the outdoor unit 2a is also referred to as the parent outdoor unit 2a, and the outdoor unit 2b is also referred to as the child outdoor unit 2b.

(Basic operation)
FIG. 6 is a flowchart showing an example of a control procedure for each outdoor unit 2a, 2b related to setting the refrigerant circuit state of the present invention, after the air conditioning apparatus 10 is installed, from when power is supplied to the air conditioning apparatus 10 until operation starts.

When power is supplied to the parent outdoor unit 2a and the child outdoor unit 2b, the control device 110a of the parent outdoor unit 2a judges the refrigerant circuit state of the parent outdoor unit 2a (steps 101, 102). The refrigerant circuit state of the parent outdoor unit 2a is judged by the CPU 111a based on whether the first refrigerant circuit state or the second refrigerant circuit state is selected by the refrigerant circuit selection unit 113a of the control device 110a. The CPU 111a stores the judgment result of the refrigerant circuit state in the memory unit 112a.

The supply of power to the parent outdoor unit 2a and the child outdoor unit 2b is performed after each outdoor unit 2a, 2b and each indoor unit 8a to 8c are connected via the connection pipes. As described above, in the case of the free-heating and cooling system air conditioner 10 shown in FIG. 1, each outdoor unit 2a, 2b must both be in the first refrigerant circuit state. On the other hand, in the case of the cooling/heating switching system air conditioner 20 shown in FIG. 2, each outdoor unit 2a, 2b must both be in the second refrigerant circuit state.

Then, the CPU 111a of the control device 110a generates a status signal including information about the refrigerant circuit state selected by the parent outdoor unit 2a, and transmits the generated status signal from the communication unit 114a to the communication unit 114b of the child outdoor unit 2b (step 103). Specifically, when the first refrigerant circuit state is selected by the parent outdoor unit 2a, a status signal about the first refrigerant circuit state is transmitted, and when the second refrigerant circuit state is selected by the parent outdoor unit 2a, a status signal about the second refrigerant circuit state is transmitted.

The control device 110b of the child outdoor unit 2b then receives the status signal via the communication unit 114b, and sets the child outdoor unit 2b to the same refrigerant circuit state as the refrigerant circuit state selected by the parent outdoor unit 2a based on the received status signal (step 104). Specifically, the CPU 111b of the child outdoor unit 2b sets the child outdoor unit 2b to the first refrigerant circuit state when the child outdoor unit 2b receives a status signal related to the first refrigerant circuit state, and sets the child outdoor unit 2b to the second refrigerant circuit state when the child outdoor unit 2b receives a status signal related to the second refrigerant circuit state. The CPU 111b may store the received status signal in the storage unit 112b.

As described above, by the CPU 111b selecting the refrigerant circuit state included in the state signal transmitted from the parent outdoor unit 2a, even if the refrigerant circuit state of the child outdoor unit 2b is mistakenly set to a state different from the refrigerant circuit state of the parent outdoor unit 2a by the operation of the refrigerant circuit selection unit 113b, the refrigerant circuit state of the child outdoor unit 2b is switched to the same refrigerant circuit state as the parent outdoor unit 2a. This makes it possible to set the parent outdoor unit 2a and the child outdoor unit 2b to the same refrigerant circuit state even if the refrigerant circuit state of the child outdoor unit 2b is mistakenly selected.

After the setting of the refrigerant circuit state of the child outdoor unit 2b is completed, the parent outdoor unit 2a and the child outdoor unit 2b start operating (step 105). Operation control commands for the child outdoor unit 2b (such as the operating mode such as cooling/heating and the rotation speed of the compressor 21 according to the air conditioning capacity required by the indoor units 8a to 8c) are transmitted from the parent outdoor unit 2a to the child outdoor unit 2b. The communication unit 114a of the parent outdoor unit 2a and the communication unit 114b of the child outdoor unit 2b communicate with each other at a predetermined interval, so that the parent outdoor unit 2a can know whether the power supply to the child outdoor unit 2b has been cut off, and can periodically obtain the operating state of the child outdoor unit 2b (such as the rotation speed of the compressor 21 and the rotation speed of the outdoor fan 26). At this time, the detection values of various sensors of the child outdoor unit 2b may be transmitted to the parent outdoor unit 2a. This allows the parent outdoor unit 2a to know the operating state of the child outdoor unit 2b.

(Operation resumes when power is restored)
Next, the operation of restarting the parent outdoor unit 2a and the child outdoor unit 2b after power recovery will be described.

Figure 7 is a flowchart showing an example of the control procedure for each outdoor unit 2a, 2b related to setting the refrigerant circuit state of the present invention from when the power supply to the parent outdoor unit 2a and the child outdoor unit 2b is cut off and then when the power supply to these units is resumed until the start of operation.

When the supply of power to the parent outdoor unit 2a is resumed after the power outage is restored, the control device 110a of the parent outdoor unit 2a checks the refrigerant circuit state of the parent outdoor unit 2a (steps 201, 202). The refrigerant circuit state of the parent outdoor unit 2a is determined by the CPU 111a based on whether the refrigerant circuit selection unit 113a in the control device 110a has selected the first refrigerant circuit state or the second refrigerant circuit state, as described above. The CPU 111a stores the determination result of the refrigerant circuit state in the memory unit 112a.

Next, the CPU 111a of the control device 110a generates a status signal including information about the confirmed refrigerant circuit status of the parent outdoor unit 2a, and transmits the generated status signal from the communication unit 114a to the communication unit 114b of the child outdoor unit 2b (step 203).

Then, the control device 110b of the child outdoor unit 2b sets the child outdoor unit 2b to the same refrigerant circuit state as the refrigerant circuit state selected in the parent outdoor unit 2a based on the state signal received by the communication unit 114b (step 204). After the setting of the refrigerant circuit state of the child outdoor unit 2b is completed, the operation of the parent outdoor unit 2a and the child outdoor unit 2b is resumed (step 205).

According to this embodiment, even if the power supply to the parent outdoor unit 2b and the child outdoor unit 2b is interrupted, the refrigerant circuit state of the child outdoor unit 2b can be set based on the state signal generated according to the refrigerant circuit state set by the refrigerant circuit selection unit 113a of the parent outdoor unit 2a when power is restored, and operation can be resumed. As a result, even if the refrigerant circuit state of the child outdoor unit 2b is reset due to a power interruption, the refrigerant circuit state of the child outdoor unit 2b can be automatically set to the refrigerant circuit state of the parent outdoor unit 2a before the reset as the power supply is resumed. Therefore, it is not necessary for an operator to reset the refrigerant circuit state of the parent outdoor unit 2a. Note that even if the power supply to only the parent outdoor unit 2a is interrupted, the refrigerant circuit state of the child outdoor unit 2b may be reset in the same manner as described above.

Figure 8 is a flowchart showing an example of the control procedure for each outdoor unit 2a, 2b related to the setting of the refrigerant circuit state of the present invention from when the power supply to only the child outdoor unit 2b is cut off and then the power supply to the child parent outdoor unit 2b is resumed until the start of operation.

As described above, the communication unit 114a of the parent outdoor unit 2a and the communication unit 114b of the child outdoor unit 2b communicate periodically, so the parent outdoor unit 2a can determine whether the power supply to the child outdoor unit 2b has been interrupted by whether the periodic communication is being performed. When it detects that the power supply to the child outdoor unit 2b has been resumed due to the resumption of communication with the child outdoor unit 2b that had been interrupted, the control device 110a of the parent outdoor unit 2a generates a status signal including the refrigerant circuit status of the parent outdoor unit 2a and transmits it to the child outdoor unit 2b (steps 301, 302).

At this time, the control device 110a may determine the refrigerant circuit state of the parent outdoor unit 2a again based on the refrigerant circuit selection unit 113a, or if the refrigerant circuit state determined when the parent outdoor unit 2a started operating is stored in the memory unit 112a, the control device 110a may read out the refrigerant circuit state from the memory unit 112a.

Then, the control device 110b of the child outdoor unit 2b sets the child outdoor unit 2b to the same refrigerant circuit state as the refrigerant circuit state selected by the parent outdoor unit 2a based on the state signal received by the communication unit 114b (step 303). After the setting of the refrigerant circuit state of the child outdoor unit 2b is completed, the operation of the child outdoor unit 2b is resumed (step 304).

According to this embodiment, when the power supply to the child outdoor unit 2b is interrupted and then restored, the refrigerant circuit state of the child outdoor unit 2b can be set based on a state signal including the refrigerant circuit state of the parent outdoor unit 2a, and operation can be resumed. As a result, even if the refrigerant circuit state of the child outdoor unit 2b is reset due to a power interruption, the refrigerant circuit state of the child outdoor unit 2b can be automatically set to the refrigerant circuit state of the parent outdoor unit 2a before the reset when the power supply to the child outdoor unit 2a is resumed.

As described above, according to this embodiment, in an air conditioning apparatus equipped with multiple outdoor units 2a, 2b that can select between a cooling/heating switching system and a cooling/heating free system, all outdoor units 2a, 2b can be unified into a cooling/heating switching system or a cooling/heating free system. This can reliably prevent malfunctions of the air conditioning apparatus caused by a mixture of outdoor units using the cooling/heating free system and outdoor units using the cooling/heating switching system.

In addition, according to this embodiment, even if the power supply to the parent outdoor unit 2a and the child outdoor unit 2b is cut off due to a power outage or the like, the refrigerant circuit state of the child outdoor unit 2a can be automatically restored to the refrigerant circuit state before the power outage when power is restored, so that operation of the parent outdoor unit 2a and the child outdoor unit 2b can be resumed without the need for an operator to reset the refrigerant circuit state.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment and can of course be modified in various ways.

For example, in the above embodiment, the air conditioning apparatus 10, 20 is described as having two outdoor units 2a, 2b and three indoor units 8a to 8c, but the number of outdoor units and indoor units is not limited to this example, and there may be three or more outdoor units, and two or four or more indoor units. If there are three or more outdoor units, one of the outdoor units is designated as the parent outdoor unit, and the refrigerant circuit state of the remaining outdoor units is adjusted to the refrigerant circuit state of the parent outdoor unit.

In the above embodiment, an example was described in which three connecting pipes (high pressure gas pipe 30, low pressure gas pipe 31, and liquid pipe 32) were used as the cooling/heating free type air conditioning device 10, but this is not limited thereto, and the cooling/heating free type air conditioning device may be configured using two connecting pipes.

Furthermore, in the above embodiment, a three-way valve (first three-way valve 22, second three-way valve 23) is used as the first flow path switching means, but this is not limited thereto, and other switching valves such as a four-way valve may be used. Similarly, a four-way valve 29 is used as the second flow path switching means, but this is not limited thereto, and for example, two electromagnetic opening and closing valves may be used as shown in FIG. 9.

Figure 9 is a refrigerant circuit diagram of outdoor units 2a and 2b in which two electromagnetic on-off valves (first electromagnetic on-off valve 29a and second electromagnetic on-off valve 29b) are used as the second flow path switching means. The first electromagnetic on-off valve 29 and the second electromagnetic on-off valve are both switching valves that only open and close. The first electromagnetic on-off valve 29a is installed in the outdoor unit high-pressure gas pipe 33, and switches between communication and cut-off between the discharge side of the compressor 21 and the stop valve 44 in response to commands from the control devices 110a and 110b. The second electromagnetic on-off valve 29b is installed in the refrigerant piping 37 connecting the outdoor unit high-pressure gas pipe 33 and the outdoor unit low-pressure gas pipe 34, and switches between communication and cut-off between the outdoor unit high-pressure gas pipe 33 and the outdoor unit low-pressure gas pipe 34 in response to commands from the control devices 110a and 110b.

When the outdoor units 2a and 2b are outdoor units of the cooling/heating free system (first refrigerant circuit state), the first solenoid on-off valve 29a is set to the ON state in all cases of heating only operation, cooling only operation, heating-dominated operation, and cooling-dominated operation, and the second solenoid on-off valve 29b is set to the OFF state in all of the above cases. Also, when the outdoor units 2a and 2b are outdoor units of the cooling/heating switching system (second refrigerant circuit state), the first solenoid on-off valve is set to OFF and the second solenoid on-off valve is set to ON during cooling operation, and the first solenoid on-off valve is set to ON and the second solenoid on-off valve 29b is set to OFF during heating operation.

2a...Outdoor unit (main outdoor unit)
2b...Outdoor unit (child outdoor unit)
6a, 6b, 6c... Diversion unit 8a, 8b, 8c... Indoor unit 10... Air conditioner of free cooling and heating system 20... Air conditioner of switching cooling and heating system 21... Compressor 22... First three-way valve (first flow path switching means)
23...Second three-way valve (first flow path switching means)
24...First outdoor heat exchanger 25...Second outdoor heat exchanger 29...Four-way valve (second flow path switching means)
30...High pressure gas pipe (gas pipe)
31: Low pressure gas pipe 32: Liquid pipe 81: Indoor heat exchanger 110a, 110b: Control device 111a, 111b: CPU
112a, 112b...Memory unit 113a, 113b...Refrigerant circuit selection unit 114a, 114b...Communication unit

Claims (7)

An air-conditioning apparatus comprising a plurality of outdoor units, a plurality of indoor units, and a plurality of connection pipes connecting each of the indoor units in parallel to the plurality of outdoor units, and capable of selecting either a first refrigerant circuit state in which each of the indoor units can individually perform a cooling operation or a heating operation, or a second refrigerant circuit state in which each of the indoor units can simultaneously perform a cooling operation or a heating operation,
each of the outdoor units includes a compressor, an outdoor heat exchanger, a first flow path switching means for selectively connecting one refrigerant inlet or outlet of the outdoor heat exchanger to a refrigerant suction pipe or a refrigerant discharge pipe of the compressor, a second flow path switching means for connecting the refrigerant suction pipe and the refrigerant discharge pipe to a first gas pipe and a second gas pipe, respectively, which are the plurality of connecting pipes, in the first refrigerant circuit state, a communication unit for communicating between the outdoor units, and a refrigerant circuit selection unit for selecting either the first refrigerant circuit state or the second refrigerant circuit state;
after the air conditioning apparatus is installed, when either the first refrigerant circuit state or the second refrigerant circuit state is selected in one of the plurality of outdoor units during the period from when power is supplied to the air conditioning apparatus until operation starts , a state signal including information about the selected refrigerant circuit state is transmitted from a communication unit of the one outdoor unit to a communication unit of the other outdoor units,
The other outdoor units that have received the status signal select the same refrigerant circuit status as the refrigerant circuit status selected by the one outdoor unit. The air conditioning apparatus according to claim 1,
The refrigerant circuit selection unit is a switching operation unit that selects either the first refrigerant circuit state or the second refrigerant circuit state, and the state signal includes information regarding the refrigerant circuit state selected by the switching operation unit. The air conditioning apparatus according to claim 1 or 2,
Among the plurality of outdoor units, the one outdoor unit is set as a parent outdoor unit, and the other outdoor units are set as child outdoor units that operate according to an instruction from the parent outdoor unit,
The child outdoor unit selects the same refrigerant circuit state as the refrigerant circuit state selected by the parent outdoor unit, based on the state signal transmitted from the parent outdoor unit. The air conditioning apparatus according to claim 2,
Among the plurality of outdoor units, the one outdoor unit is set as a parent outdoor unit, and the other outdoor units are set as child outdoor units that operate according to an instruction from the parent outdoor unit,
When the refrigerant circuit state selected by the switching operation unit of the child outdoor unit differs from the refrigerant circuit state included in the state signal transmitted from the parent outdoor unit, the child outdoor unit selects the refrigerant circuit state included in the state signal transmitted from the parent outdoor unit. The air conditioning apparatus according to claim 4,
When the supply of power to the plurality of outdoor units is started or resumed, the parent outdoor unit checks the refrigerant circuit state selected by the switching operation unit of the parent outdoor unit, and transmits the checked refrigerant circuit state to the child outdoor unit by including it in the state signal. The air conditioning apparatus according to claim 3,
When the supply of power to the child outdoor unit is started or resumed, the parent outdoor unit includes the refrigerant circuit state selected in the parent outdoor unit in the state signal and transmits the state signal to the child outdoor unit. The air conditioning apparatus according to claim 1 or 2,
In the first refrigerant circuit state, three connecting pipes, that is, the first gas pipe, the second gas pipe, and a liquid pipe connected to the other refrigerant inlet/outlet of the outdoor heat exchanger, are used as the multiple connecting pipes,
In the second refrigerant circuit state, two connecting pipes, that is, the first gas pipe and the liquid pipe, are used as the plurality of connecting pipes.

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