JP2016142453A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable air conditioner.SOLUTION: An air conditioner A comprises: an outdoor unit 10, indoor units 20a-20d; high pressure gas-side piping 3 connecting a discharge side of a compressor 11 and other-end sides u of indoor heat exchangers 21a-21d; high pressure gas-side solenoid valves 61a-61d switching communication/cutoff states between the outlet side of the compressor 11 and the indoor heat exchangers 21a-21d; low pressure gas-side piping 4 connecting an intake side of the compressor 11 and sides of the high pressure gas-side piping 3 downstream from the high pressure gas-side solenoid valves 61a-61d; low pressure gas-side solenoid valves 62a-62d switching communication/cutoff states between the intake side of the compressor 11 and the indoor heat exchangers 21a-21d; and liquid-side piping 5 connecting one-end sides n of the indoor heat exchangers 21a-21d and the other end 12u of the outdoor heat exchanger 12 through indoor expansion valves 23a-23d and an outdoor expansion valve 16.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an air conditioner.

  There is known a multi-type air conditioner in which a plurality of indoor units are connected to one outdoor unit, and each indoor unit can be individually operated / stopped. Multi-type air conditioners have the advantage of requiring a small installation space for outdoor units and the advantage of easy expansion of indoor units, and are widely used for air conditioning in offices and the like.

  By the way, in a multi-type air conditioner, some of the plurality of indoor units perform heating operation, and the remaining indoor units are in a stopped state (switch-off state or the room temperature reaches a set temperature and temporarily May be in a stopped state). With regard to the stopped indoor unit, generally, the indoor expansion valve is opened slightly in order to suppress wasteful heat consumption, and the flow rate of the refrigerant flowing through the indoor unit is reduced.

  However, when the number of indoor units in the stopped state increases in the above-described method, the ratio of the refrigerant supplied to the indoor unit during the heating operation among the refrigerant discharged from the compressor decreases, and thus the operation efficiency decreases. There is a problem.

  Considering such a problem, for example, the following technologies are known as techniques for solving the shortage of refrigerant in an indoor unit that is performing a heating operation. That is, in Patent Document 1, when a heating operation is performed with some of the indoor units and the remaining indoor units are stopped, the indoor valve in the stopped state is closed by closing the electromagnetic valve provided in the mainstream side gas connection pipe. It is described that liquid refrigerant is prevented from accumulating in the machine.

JP 2006-145185 A

  In Patent Literature 1, for example, when a heating operation is performed with a large number of indoor units and a small number of indoor units are stopped, the indoor heat exchanger of the stopped indoor unit is closed by closing the electromagnetic valve described above. Is filled with a gas refrigerant. Thereby, the condensation of the refrigerant is suppressed in the indoor heat exchangers of a large number of stopped indoor units, and the above-described refrigerant shortage is solved.

  However, in Patent Document 1, when a heating operation is performed with a small number of indoor units and a large number of indoor units are stopped, a large amount of gas is generated when the indoor heat exchanger of the stopped indoor units is filled with a gas refrigerant. Surplus refrigerant is generated. In particular, when the outside air temperature is relatively high, there is a problem that the indoor heat exchanger of the indoor unit that is performing the heating operation is filled with surplus refrigerant (liquid refrigerant), leading to a reduction in its condensing capacity. Furthermore, there is a possibility that an excessive load is applied to the compressor due to the decrease in the condensing capacity, and the heating operation is temporarily stopped.

  In Patent Document 1, when a small number of indoor units perform cooling operation and a large number of indoor units are stopped, the condensation capacity of the outdoor heat exchanger tends to be excessive with respect to the evaporation capacity of the indoor heat exchanger. . In particular, when the outside air temperature is relatively low, the pressure on the discharge side of the compressor falls below the allowable range, or the indoor heat exchanger of the indoor unit that is performing the cooling operation is frosted. May be suspended.

  As described above, in the technique described in Patent Document 1, when a small number of indoor units are performing air conditioning operation (heating operation or cooling operation), the air conditioning operation may be temporarily stopped by protection control of the compressor or the like. There is room for further improvement of reliability.

  Then, this invention makes it a subject to provide an air conditioner with high reliability.

  In order to solve the above-described problem, an air conditioner according to the present invention switches a connection destination of one end of a compressor, an outdoor heat exchanger, and the outdoor heat exchanger to the suction side / discharge side of the compressor. An outdoor unit having a flow path switching means, an outdoor expansion valve connected to the other end of the outdoor heat exchanger, an indoor heat exchanger, and an indoor expansion valve connected to one end of the indoor heat exchanger; A plurality of indoor units, a discharge side of the compressor, a first pipe connecting the other end of each of the indoor heat exchangers, and the first pipe, A plurality of first opening / closing means for switching communication / blocking between the discharge side and the indoor heat exchanger for each of the indoor heat exchangers, the suction side of the compressor, and the first opening / closing means in the first pipe A second pipe connecting the downstream side of the second pipe and the second pipe A plurality of second opening / closing means for switching the communication between the suction side of the compressor and the indoor heat exchanger for each of the indoor heat exchangers, and the one end of each of the indoor heat exchangers; 3rd piping which connects the said other end of the said outdoor heat exchanger via the said indoor expansion valve and the said outdoor expansion valve, It is characterized by the above-mentioned.

  According to the present invention, a highly reliable air conditioner can be provided.

It is a block diagram of the air conditioner which concerns on one Embodiment of this invention. It is a flowchart which shows the process which a control apparatus performs. It is explanatory drawing which shows the state of each valve in a 1st mode, and the flow of a refrigerant | coolant. It is explanatory drawing which shows the state of each valve in a 2nd mode, and the flow of a refrigerant | coolant. It is explanatory drawing which shows the state of each valve in a 3rd mode, and the flow of a refrigerant | coolant. It is explanatory drawing which shows the state of each valve in a 5th mode, and the flow of a refrigerant | coolant.

<Embodiment>
<Configuration of air conditioner>
Hereinafter, for example, the indoor units 20a, 20b, 20c, and 20d (see FIG. 1) are referred to as “indoor units 20a to 20d”.
FIG. 1 is a configuration diagram of an air conditioner A according to the present embodiment. The air conditioner A is an apparatus that performs air conditioning such as temperature and humidity of indoor air by circulating a refrigerant in a heat pump cycle. As shown in FIG. 1, the air conditioner A includes an outdoor unit 10, indoor units 20a to 20d, a high-pressure gas side pipe 3 (first pipe), a low-pressure gas side pipe 4 (second pipe), a liquid A side pipe 5 (third pipe) and refrigerant switching units 60a to 60d are provided.

(Outdoor unit)
The outdoor unit 10 includes a compressor 11, an outdoor heat exchanger 12, an outdoor blower fan 13, a four-way valve 14 (flow path switching means), a check valve 15, an outdoor expansion valve 16, and a control device 17 ( Control means).
The compressor 11 is a device that compresses the refrigerant sucked through the low pressure gas side main flow pipe 42 and discharges the compressed refrigerant through the high pressure gas side main flow pipe 31. Although not shown in FIG. 1, an accumulator for performing gas-liquid separation is provided on the suction side of the compressor 11.

The outdoor heat exchanger 12 is a heat exchanger for exchanging heat between the refrigerant and the outside air sent from the outdoor blower fan 13. One end 12 n of the outdoor heat exchanger 12 is connected to the suction side or discharge side of the compressor 11 by switching the four-way valve 14, and the other end 12 u is connected to the liquid side pipe 5.
The outdoor fan 13 is a fan that sends outside air to the outdoor heat exchanger 12, and is installed in the vicinity of the outdoor heat exchanger 12.

The four-way valve 14 is a valve that switches the connection destination of the one end 12 n of the outdoor heat exchanger 12 to the suction side / discharge side of the compressor 11.
Of the two connected states of the four-way valve 14, the solid line indicates that the end 12n of the outdoor heat exchanger 12 is connected to the compressor 11 via the pipe p1, the four-way valve 14, the pipe p2, and the low-pressure gas side main flow pipe 42 (part). It shows the state connected to the suction side. The broken line indicates a state in which one end 12n of the outdoor heat exchanger 12 is connected to the discharge side of the compressor 11 via the pipe p1, the four-way valve 14, the pipe p3, and the high-pressure gas side main flow pipe 31 (part). Is shown.
Note that the path through which the refrigerant actually flows is determined by the connection state of the four-way valve 14 and the open / close states of the high pressure gas side solenoid valves 61a to 61d and the low pressure gas side solenoid valves 62a to 62d described later.

The check valve 15 is a valve for preventing the gas refrigerant discharged from the compressor 11 via the high pressure gas side main flow pipe 31 from flowing into the low pressure gas side main flow pipe 42. Instead of the four-way valve 14 and the check valve 15, a three-way valve (flow path switching means) that switches the connection destination of the one end 12n of the outdoor heat exchanger 12 to the suction side / discharge side of the compressor 11 is provided. Also good.
The outdoor expansion valve 16 adjusts the flow rate of the refrigerant flowing through the outdoor heat exchanger 12 or depressurizes the refrigerant when the outdoor heat exchanger 12 is used as an evaporator, and is provided in the liquid side main flow pipe 52. ing.

  Although not shown, the control device 17 includes electronic circuits such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and various interfaces. Then, the program stored in the ROM is read out and expanded in the RAM, and the CPU executes various processes. The control device 17 has a function of controlling each device of the outdoor unit 10 and controlling each electromagnetic valve of the refrigerant switching units 60a to 60d. The processing executed by the control device 17 will be described later.

(Indoor unit)
The indoor unit 20a includes an indoor heat exchanger 21a, an indoor blower fan 22a, and an indoor expansion valve 23a. The indoor heat exchanger 21a is a heat exchanger for exchanging heat between the refrigerant and the indoor air sent from the indoor blower fan 22a. The indoor blower fan 22a is a fan that sends indoor air into the indoor heat exchanger 21a, and is installed in the vicinity of the indoor heat exchanger 21a.

The indoor expansion valve 23a adjusts the flow rate of the refrigerant flowing through the indoor heat exchanger 21a, or depressurizes the refrigerant when the indoor heat exchanger 21a is used as an evaporator, and is provided in the liquid side connection pipe 51a. ing. That is, the indoor expansion valve 23a is connected to one end n of the indoor heat exchanger 21a via the liquid side connection pipe 51a (part).
In addition, the indoor unit 20a includes a control device (not shown) that controls the indoor blower fan 22a, the indoor expansion valve 23a, and the like based on information input from the control device 17 of the outdoor unit 10.

  The other indoor units 20b to 20d connected in parallel with the indoor unit 20a have the same configuration as that of the indoor unit 20a, and thus the description thereof is omitted.

(High pressure gas side piping)
The high-pressure gas side pipe 3 is a pipe that connects the discharge side of the compressor 11 and the other ends u of the indoor heat exchangers 21a to 21d. The high-pressure gas side pipe 3 includes a high-pressure gas side main pipe 31 and high-pressure gas side connection pipes 32a to 32d, and is branched into four corresponding to the indoor heat exchangers 21a to 21d.

The high-pressure gas side main flow pipe 31 is a pipe that guides the high-temperature and high-pressure gas refrigerant discharged from the compressor 11 to the high-pressure gas side connection pipes 32 a to 32 d, and is connected to the discharge side of the compressor 11.
The high-pressure gas side connecting pipe 32a is a pipe that guides the gas refrigerant flowing (divided) from the high-pressure gas side main flow pipe 31 to the indoor heat exchanger 21a. The high-pressure gas side main pipe 31 and the other end of the indoor heat exchanger 21a (The same applies to the other high-pressure gas side connection pipes 32b to 32d).

(Low pressure gas side piping)
The low pressure gas side pipe 4 is a pipe connecting the suction side of the compressor 11 and the downstream side of the high pressure gas side solenoid valve 61a in the high pressure gas side pipe 3. The low pressure gas side pipe 4 includes low pressure gas side connection pipes 41a to 41d and a low pressure gas side main flow pipe 42, and is branched into four corresponding to the indoor heat exchangers 21a to 21d.

The low pressure gas side connection pipe 41 a is a pipe that guides the low pressure gas refrigerant flowing from the indoor heat exchanger 21 a to the low pressure gas side main flow pipe 42. The low pressure gas side connection pipe 41a is connected to the downstream side of the high pressure gas side solenoid valve 61a in the high pressure gas side connection pipe 32a and the low pressure gas side main flow pipe 42 (the other low pressure gas side connection pipes 41b to 41b). The same applies to 41d).
The low-pressure gas side main flow pipe 42 is a pipe that guides the gas refrigerant flowing (merged) from the low-pressure gas side connection pipes 41 a to 41 d to the suction side of the compressor 11, and is connected to the suction side of the compressor 11.

(Liquid side piping)
The liquid side pipe 5 is a pipe that connects one end n of each of the indoor heat exchangers 21 a to 21 d and the other end 12 u of the outdoor heat exchanger 12 via the indoor expansion valves 23 a to 23 d and the outdoor expansion valve 16. It is. The liquid side pipe 5 includes liquid side connection pipes 51a to 51d and a liquid side main flow pipe 52, and is branched into four corresponding to the indoor heat exchangers 21a to 21d.

The liquid side connection pipe 51a is connected to one end n of the indoor heat exchanger 21a and the liquid side main flow pipe 52. As described above, the liquid-side connection pipe 51a is provided with the indoor expansion valve 23a (the same applies to the other liquid-side connection pipes 51b to 51d).
The liquid side main flow pipe 52 is connected to the other end 12 u of the outdoor heat exchanger 12. In the liquid side main flow pipe 52, the outdoor expansion valve 16 is provided at a position closer to the outdoor heat exchanger 12 than the connection places with the liquid side connection pipes 51a to 51d.

(Refrigerant switching unit)
The refrigerant switching unit 60a switches the direction of the refrigerant flowing into the indoor heat exchanger 21a, and includes a high pressure gas side electromagnetic valve 61a (first opening / closing means) and a low pressure gas side electromagnetic valve 62a (second opening / closing means). It is equipped with. In addition, since it is the same also about the other refrigerant | coolant switching units 60b-60d, below, the refrigerant | coolant switching unit 60a is demonstrated.

  The high-pressure gas side solenoid valve 61a is a solenoid valve that switches communication / blocking between the discharge side of the compressor 11 and the indoor heat exchanger 21a, and is provided in the high-pressure gas side connection pipe 32a. The high-pressure gas side electromagnetic valve 61a opens and closes in response to a command from the control device 17.

  The low pressure gas side electromagnetic valve 62a is an electromagnetic valve that switches communication / blocking between the suction side of the compressor 11 and the indoor heat exchanger 21a, and is provided in the low pressure gas side connection pipe 41a. The low-pressure gas side electromagnetic valve 62a opens and closes in response to a command from the control device 17.

<Operation of air conditioner>
FIG. 2 is a flowchart illustrating processing executed by the control device. In the following description, the control device 17 (see FIG. 1) of the outdoor unit 10 and the control devices (not shown) of the indoor units 20a to 20d are collectively referred to as “control device”.
In step S101, the control device determines whether there is an indoor unit that performs the heating operation among the indoor units 20a to 20d. When there is an indoor unit that performs the heating operation (S101: Yes), the processing of the control device proceeds to step S102.

In step S102, the control device determines whether there is no indoor unit that performs the cooling operation among the indoor units 20a to 20d. When there is no indoor unit that performs the cooling operation (S102: Yes), the control device proceeds to step S103.
In step S103, the control device calculates a ratio f occupied by the number of indoor units performing the heating operation among the indoor units 20a to 20d.

In step S104, the control device determines whether or not the ratio f calculated in step S103 is greater than a predetermined threshold F. This predetermined threshold value F (for example, 0.25) is a threshold value that is a criterion for determining whether or not the indoor heat exchanger of the stopped indoor unit is filled with the gas refrigerant.
When the ratio f occupied by the indoor unit in the heating operation is larger than the predetermined threshold F (S104: Yes), the process of the control device proceeds to step S105.

In step S105, the control device executes the first mode.
FIG. 3 is an explanatory diagram showing the open / close state of each valve and the flow of the refrigerant in the first mode. In FIG. 3, the open valve and the driving fan are illustrated in white, and the closed valve and the stopped fan are illustrated in black (the same applies to FIGS. 4 to 6). . Moreover, in the example shown in FIG. 3, the ratio f which the indoor units 20a-20c (three units) which perform heating operation among the four indoor units 20a-20d occupies 0.75 (> F = 0.25). Yes, the heating load is relatively large.

When executing the first mode, the control device controls the four-way valve 14 so that the connection destination of the one end 12 n of the outdoor heat exchanger 12 is the suction side of the compressor 11.
Moreover, regarding the indoor units 20a to 20c that perform the heating operation, the control device opens the high pressure gas side electromagnetic valves 61a to 61c so that the discharge side of the compressor 11 and the indoor heat exchangers 21a to 21c communicate with each other. The gas side solenoid valves 62a to 62c are closed. In other words, the control device closes the low pressure gas side electromagnetic valves 62a to 62c when the discharge side of the compressor 11 and the indoor heat exchangers 21a to 21c are communicated with each other by the high pressure gas side electromagnetic valves 61a to 61c.

  Further, for the stopped indoor unit 20d, the control device opens the low pressure gas side electromagnetic valve 62d and closes the high pressure gas side electromagnetic valve 61d so that the suction side of the compressor 11 and the indoor heat exchanger 21d communicate with each other. . In other words, the control device closes the high pressure gas side solenoid valve 61d when the suction side of the compressor 11 and the indoor heat exchanger 21d are communicated with each other by the low pressure gas side solenoid valve 62d. Further, the control device stops the indoor blower fan 22d and closes the indoor expansion valve 23d.

  The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchangers 21 a to 21 c through the high-pressure gas side pipe 3. The gas refrigerant flowing through the indoor heat exchangers 21a to 21c exchanges heat with the indoor air sent from the indoor air blowing fans 22a to 22c, and is condensed to become liquid refrigerant. The liquid refrigerant flowing out of the indoor heat exchangers 21 a to 21 c is decompressed by the outdoor expansion valve 16 in the process of flowing through the liquid side pipe 5, and the decompressed refrigerant flows into the outdoor heat exchanger 12. The refrigerant flowing through the outdoor heat exchanger 12 evaporates by exchanging heat with the outside air sent from the outdoor blower fan 13 and becomes a low-pressure gas refrigerant. The gas refrigerant that has flowed out of the outdoor heat exchanger 12 goes to the suction side of the compressor 11 via the four-way valve 14.

  Further, with respect to the stopped indoor unit 20d, the low-pressure gas side solenoid valve 62d is open, so that the indoor heat exchanger 21d communicates with the suction side of the compressor 11 via the low-pressure gas side pipe 4. Therefore, the refrigerant in the indoor heat exchanger 21d is recovered (sucked) to the suction side of the compressor 11 via the low-pressure gas side pipe 4. Thereby, the refrigerant | coolant which 21d of indoor heat exchangers hold | maintains can be decreased, and the refrigerant | coolant which circulates to the indoor units 20a-20c which perform heating operation can fully be ensured.

In step S104 of FIG. 2, when the ratio f occupied by the indoor unit in the heating operation is equal to or less than the predetermined threshold F (S104: No), the process of the control device proceeds to step S106.
In step S106, the control device executes the second mode. As a condition for performing the second mode, a condition that the absolute value of the difference between the outside air temperature (≦ the room temperature) and the room temperature is not more than a predetermined threshold (that is, the heating load is small) may be added. .

  FIG. 4 is an explanatory diagram showing the open / close state of each valve and the flow of the refrigerant in the second mode. In the example shown in FIG. 4, the ratio f occupied by the indoor unit (one unit) that performs the heating operation among the four indoor units 20a to 20d is 0.25 (≦ F = 0.25), and the heating load Is relatively small.

When executing the second mode, the control device controls the four-way valve 14 so that the connection destination of the one end 12 n of the outdoor heat exchanger 12 is the suction side of the compressor 11.
Moreover, regarding the indoor unit 20a that performs the heating operation, the control device opens the high-pressure gas side solenoid valve 61a so that the discharge side of the compressor 11 communicates with the indoor heat exchanger 21a, and opens the low-pressure gas side solenoid valve 62a. close up.
The control device also opens the high pressure gas side electromagnetic valves 61b to 61d so that the discharge side of the compressor 11 and the indoor heat exchangers 21b to 21d communicate with each other for the stopped indoor units 20b to 20d. The side solenoid valves 62d to 62d are closed. This is different from the first mode (see FIG. 3). Further, the control device closes or slightly opens the indoor expansion valves 23b to 23d included in the stopped indoor units 20b to 20d.

  The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchangers 21 a to 21 d via the high-pressure gas side pipe 3. Here, with respect to the stopped indoor units 20b to 20d, since the indoor expansion valves 23b to 23d are closed (or slightly opened), the refrigerant from the compressor 11 is transferred to the indoor heat exchangers 21b to 21d. Accumulated. That is, in the indoor heat exchangers 21b to 21d, the high-pressure gas refrigerant is condensed by heat exchange (natural convection) with room air and stored as liquid refrigerant.

  In this way, by holding the liquid refrigerant in the indoor heat exchangers 21b to 21d, it is possible to suppress excess liquid refrigerant from being accumulated in the indoor heat exchanger 21a of the indoor unit 20a that is performing the heating operation. Therefore, the condensing capacity of the indoor heat exchanger 21a can be maximized, and the operation efficiency at the time of performing the heating operation can be increased as compared with the conventional case. Further, in the indoor heat exchanger 21a, the refrigerant is sufficiently condensed by heat exchange with the indoor air sent from the indoor blower fan 22a, so that an increase in pressure in the high-pressure gas side pipe 3 is suppressed. Thereby, since the heating operation can be continued without temporarily stopping the compressor 11, the air conditioner A having higher reliability and superior comfort can be provided.

  When there is an indoor unit that performs the cooling operation in Step S102 of FIG. 2 (S102: No), the process of the control device proceeds to Step S107. For example, in some indoor units, the server room is cooled by performing a cooling operation throughout the year, and in the remaining indoor units, the room is heated by performing a heating operation in winter. In such a case, the heating operation and the cooling operation are performed simultaneously (duplicated in time) in different indoor units.

In step S107, the control device calculates a ratio g of the number of indoor units performing the heating operation to the number of indoor units performing the cooling operation.
In step S108, the control device determines whether or not the ratio g calculated in step S107 is equal to or less than a predetermined threshold G. This predetermined threshold G (for example, 1.0) is a criterion for determining whether to use the outdoor heat exchanger 12 as a condenser (third mode) or as an evaporator (fourth mode). It is a threshold value. When the ratio g is less than or equal to the predetermined threshold G (S108: Yes), the process of the control device proceeds to step S109.

In step S109, the control device executes the third mode.
FIG. 5 is an explanatory diagram showing the open / close state of each valve and the flow of the refrigerant in the third mode. In the example illustrated in FIG. 5, the ratio g of the number of indoor units (one unit) performing the heating operation to the number of indoor units (three units) performing the cooling operation is 0.33 (≦ G = 1. 0).

When executing the third mode, the control device controls the four-way valve 14 so that the connection destination of the one end 12 n of the outdoor heat exchanger 12 is on the discharge side of the compressor 11.
In addition, regarding the indoor units 20 a to 20 c that perform the cooling operation, the control device communicates the low pressure gas side electromagnetic so that the suction side of the compressor 11 and the indoor heat exchangers 21 a to 21 c communicate with each other via the low pressure gas side pipe 4. The valves 62a to 62c are opened, and the high pressure gas side electromagnetic valves 61a to 61c are closed.
Further, the control device opens the high-pressure gas side electromagnetic valve 61d so that the discharge side of the compressor 11 and the indoor heat exchanger 21d communicate with each other via the high-pressure gas side pipe 3 for the indoor unit 20d that performs the heating operation. The low pressure gas side electromagnetic valve 62d is closed.

A part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchanger 21d via the high-pressure gas side pipe 3, and the remaining gas refrigerant passes through the four-way valve 14 to the outdoor heat exchanger. 12 flows in. The refrigerant condensed in the outdoor heat exchanger 12 and the refrigerant condensed in the indoor heat exchanger 21d are decompressed by the indoor expansion valves 23a to 23c in the process of flowing through the liquid side pipe 5, and the indoor heat exchangers 21a to 21c. Head for. The refrigerant evaporated in the indoor heat exchangers 21 a to 21 c is directed to the suction side of the compressor 11 through the low-pressure gas side pipe 4.
Thus, when there are more indoor units that perform the cooling operation than indoor units that perform the heating operation, the lack of the condensing capacity can be compensated by causing the outdoor heat exchanger 12 to function as a condenser.

In step S108 of FIG. 2, when the ratio g of the indoor unit in the heating operation to the indoor unit in the cooling operation is larger than the predetermined threshold G (S108: No), the process of the control device proceeds to step S110.
In step S110, the control device executes the fourth mode. Although the detailed description of the fourth mode is omitted, the control device switches the four-way valve 14 so that the outdoor heat exchanger 12 functions as an evaporator, and switches the high-pressure gas side solenoid valves 61a to 61d and the low-pressure gas side. The open / close states of the solenoid valves 62a to 62d are switched as appropriate according to the cooling operation / heating operation.

When there is no indoor unit that performs the heating operation in step S101 of FIG. 2 (S101: No), the process of the control device proceeds to step S111. In step S111, the control device determines whether there is an indoor unit that performs a cooling operation among the indoor units 20a to 20d. When there is an indoor unit that performs the cooling operation (S111: Yes), the control device proceeds to step S112.
In step S112, the control device calculates a ratio h of the number of indoor units performing the cooling operation among the indoor units 20a to 20d.

In step S113, the control device determines whether or not the ratio h calculated in step S112 is equal to or less than a predetermined threshold value H. The predetermined threshold value H (for example, 0.25) is a threshold value that serves as a criterion for determining whether or not the indoor heat exchanger of the stopped indoor unit functions as a condenser.
When the ratio h of the indoor units in the cooling operation is equal to or less than the predetermined threshold H (S113: Yes), the processing of the control device proceeds to step S114.
In step S114, the control device executes the fifth mode. As a condition for executing the fifth mode, a condition that the absolute value of the difference between the outside air temperature (≧ indoor temperature) and the indoor temperature is not more than a predetermined threshold (that is, the cooling load is small) may be added.

  FIG. 6 is an explanatory diagram showing the state of each valve and the flow of the refrigerant in the fifth mode. In the example shown in FIG. 6, the ratio h occupied by the indoor unit 20a (one unit) performing the cooling operation among the four indoor units 20a to 20d is 0.25 (≦ H = 0.25), and the cooling load Is relatively small.

When executing the fifth mode, the control device controls the four-way valve 14 so that the connection destination of the one end 12n of the outdoor heat exchanger 12 is the suction side of the compressor 11, and closes the outdoor expansion valve 16.
In addition, for the indoor unit 20a that performs the cooling operation, the control device opens the low pressure gas side electromagnetic valve 62a so that the suction side of the compressor 11 and the indoor heat exchanger 21a communicate with each other, and opens the high pressure gas side electromagnetic valve 61a. close up.
In addition, for the stopped indoor units 20b to 20d, the control device opens the high pressure gas side solenoid valves 61b to 61d so that the discharge side of the compressor 11 and the indoor heat exchangers 21b to 21d communicate with each other, and the low pressure The gas side solenoid valves 62b to 62d are closed.

The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchangers 21 b to 21 d through the high-pressure gas side pipe 3. The gas refrigerant flowing through the indoor heat exchangers 21b to 21d is condensed by exchanging heat with room air by natural convection. As described above, in the fifth mode, the indoor heat exchangers 21b to 21d of the stopped indoor units 20b to 20d are functioned as a condenser.
The refrigerant that has flowed out of the indoor heat exchangers 21b to 21d is decompressed by the indoor expansion valve 23a in the process of flowing through the liquid side pipe 5, and the decompressed refrigerant flows into the indoor heat exchanger 21a. The refrigerant flowing through the indoor heat exchanger 21a absorbs heat from the indoor air sent from the indoor blower fan 22a and evaporates to become a low-pressure gas refrigerant. The gas refrigerant that has flowed out of the indoor heat exchanger 21 a returns to the suction side of the compressor 11 through the low-pressure gas side pipe 4.

  The outdoor heat exchanger 12 has a sufficient capacity so that the condensation capacity is not insufficient even when all of the indoor units 20a to 20d are performing the cooling operation. If the outdoor expansion valve 16 is opened and the refrigerant is circulated through the outdoor heat exchanger 12 (condenser) and the indoor heat exchanger 21a (evaporator), the condensation capacity of the outdoor heat exchanger 12 as described above. Is sufficiently secured, and its condensation capacity becomes excessive. As a result, when the outside air temperature is low, the indoor heat exchanger 21a is frosted, and there is a high possibility that the cooling operation is temporarily stopped to perform defrosting.

  On the other hand, in the present embodiment (fifth mode), the indoor heat exchangers 21b to 21d of the stopped indoor units 20b to 20d are caused to function as condensers, so that the condensation capacity is increased when the outside air temperature is low. It is possible to suppress frosting of the indoor heat exchanger 21a. That is, since the cooling operation can be continued, the air conditioner A having higher reliability and superior comfort can be provided.

In step S113 of FIG. 2, when the ratio h that the indoor unit in the cooling operation occupies is larger than the predetermined threshold value H (S113: No), the process of the control device proceeds to step S115.
In step S115, the control device executes the sixth mode. Although a detailed description of the sixth mode is omitted, the control device switches the four-way valve 14 so that the outdoor heat exchanger 12 functions as a condenser, and further increases the pressure according to the operating state of the indoor units 20a to 20d. The open / close states of the gas side solenoid valves 61a to 61d and the low pressure gas side solenoid valves 62a to 62d are appropriately switched.

If there is no indoor unit that performs the cooling operation in step S111 (S111: No), that is, if all the indoor units are stopped, the process of the control device returns to “START” (RETURN).
The control device repeats the process shown in FIG. 2 every time the heating / cooling operation of the indoor unit is switched or the operation / stop of the indoor unit is switched by an operation of a remote controller (not shown). .

<Effect>
According to the present embodiment, an appropriate amount of refrigerant required for air conditioning can be circulated by controlling each valve in accordance with the number of indoor units that perform heating operation or cooling operation and changes in the outside air temperature. Therefore, comfort as interpersonal air conditioning can be ensured under wider conditions than before, and air conditioning can be performed with high COP (Coefficient Of Performance). Moreover, according to this embodiment, heating operation is temporarily stopped for the protection of the compressor 11, and cooling operation is temporarily stopped for defrosting of an indoor heat exchanger. Therefore, the reliability of the air conditioner A can be improved as compared with the prior art.

≪Modification≫
As mentioned above, although air conditioner A concerning the present invention was explained by an embodiment, the present invention is not limited to these statements and can change variously.
For example, in the embodiment, a case has been described in which each operation mode (first to sixth modes) is determined based on the number of indoor units that perform heating operation or cooling operation, but the present invention is not limited thereto. That is, regarding the indoor unit that performs the heating operation or the cooling operation, the operation mode may be determined based on the capacity of the indoor heat exchanger. Thereby, for example, even when the capacities of the indoor heat exchangers 21a to 21d are not the same, an optimum operation mode can be selected as described below.

  That is, in the above-described embodiment, the case where the first mode is executed when the ratio f occupied by the number of indoor units performing the heating operation is larger than the predetermined threshold F has been described (S104: Yes, S105). Not exclusively. That is, the first mode is executed when the ratio of the total capacity of the indoor heat exchangers of the indoor units performing the heating operation to the capacity of the outdoor heat exchanger 12 is greater than a predetermined threshold. May be. This can prevent a large amount of liquid refrigerant from accumulating in the indoor heat exchanger of the stopped indoor unit.

Moreover, although embodiment demonstrated the case where 2nd mode was performed when the ratio f which the number of indoor units which perform heating operation is below the predetermined threshold F (S104: No, S106), it is not restricted to this. . That is, the second mode is executed when the ratio of the total capacity of the indoor heat exchangers of the indoor units performing the heating operation to the capacity of the outdoor heat exchanger 12 is equal to or less than a predetermined threshold. May be. Thereby, the liquid refrigerant can be stored in the indoor heat exchanger of the stopped indoor unit.
Note that the second mode may be executed when the above-described conditions are satisfied and the absolute value of the difference between the outside air temperature (≦ the room temperature) and the room temperature is equal to or less than a predetermined threshold value.

Moreover, although embodiment demonstrated the case where a 3rd mode was performed when the ratio g for which the indoor unit which performs heating operation is below the predetermined threshold G with respect to the indoor unit which performs cooling operation (S108: Yes) S109), but is not limited thereto. That is, when the ratio of the total value of the capacity of the indoor heat exchanger of the indoor unit that performs the heating operation to the total value of the capacity of the indoor heat exchanger of the indoor unit that performs the cooling operation is equal to or less than a predetermined threshold, The third mode may be executed. Thereby, the outdoor heat exchanger 12 can function as a condenser.
The same applies to the fourth mode in which the outdoor heat exchanger 12 functions as an evaporator.

In the embodiment, the case where the fifth mode is executed when the ratio h of the number of indoor units performing the cooling operation is equal to or less than the predetermined threshold H has been described (S113: Yes, S114). . That is, the fifth mode is executed when the ratio of the total capacity of the indoor heat exchangers of the indoor units performing the cooling operation to the capacity of the outdoor heat exchanger 12 is equal to or less than a predetermined threshold. May be. Thereby, the indoor heat exchanger of the stopped indoor unit can function as a condenser.
Note that the fifth mode may be executed when the above-described conditions are satisfied and the absolute value of the difference between the outside air temperature (≧ indoor temperature) and the indoor temperature is equal to or less than a predetermined threshold value.

  Moreover, although the air conditioner A demonstrated the structure (refer FIG. 1) provided with the four indoor units 20a-20d in embodiment, the number of the indoor units connected mutually in parallel may be three or less. Moreover, five or more may be used.

Each embodiment is described in detail for easy understanding of the present invention, and is not necessarily limited to the one having all the described configurations. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.
In addition, the above-described mechanisms and configurations are those that are considered necessary for the description, and do not necessarily indicate all the mechanisms and configurations on the product.

A air conditioner 10 outdoor unit 11 compressor 12 outdoor heat exchanger 12n one end of the outdoor heat exchanger 12u other end of the outdoor heat exchanger 13 outdoor blower fan 14 four-way valve (flow path switching means)
15 Check valve 16 Outdoor expansion valve 17 Control device (control means)
20a, 20b, 20c, 20d Indoor unit 21a, 21b, 21c, 21d Indoor heat exchanger n One end of indoor heat exchanger u Other end of indoor heat exchanger 22a, 22b, 22c, 22d Indoor fan 23a, 23b, 23c , 23d Indoor expansion valve 3 High-pressure gas side piping (first piping)
4 Low-pressure gas side piping (second piping)
5 Liquid side piping (3rd piping)
61a, 61b, 61c, 61d High pressure gas side solenoid valve (first opening / closing means)
62a, 62b, 62c, 62d Low pressure gas side solenoid valve (second opening / closing means)

Claims (5)

The compressor, the outdoor heat exchanger, the flow path switching means for switching the connection destination of one end of the outdoor heat exchanger to the suction side / discharge side of the compressor, and the other end of the outdoor heat exchanger An outdoor unit having an outdoor expansion valve;
A plurality of indoor units having an indoor heat exchanger and an indoor expansion valve connected to one end of the indoor heat exchanger;
A first pipe connecting the discharge side of the compressor and the other end of each indoor heat exchanger;
A plurality of first opening / closing means provided on the first pipe, for switching communication / blocking between the discharge side of the compressor and the indoor heat exchanger for each of the indoor heat exchangers;
A second pipe connecting the suction side of the compressor and the downstream side of the first opening / closing means in the first pipe;
A plurality of second opening / closing means provided in the second pipe, for switching communication / blocking between the suction side of the compressor and the indoor heat exchanger for each of the indoor heat exchangers;
And a third pipe connecting the one end of each of the indoor heat exchangers and the other end of the outdoor heat exchanger via the indoor expansion valve and the outdoor expansion valve. Air conditioner. Comprising control means for controlling each device of the air conditioner,
The control means includes
When communicating the discharge side of the compressor and the indoor heat exchanger by the first opening / closing means, the second opening / closing means corresponding to the indoor heat exchanger is closed,
The first opening / closing means corresponding to the indoor heat exchanger is closed when the suction side of the compressor and the indoor heat exchanger are communicated with each other by the second opening / closing means. Air conditioner as described in. The control means includes
In the case where the heating operation is performed in a part of the plurality of indoor units and the remaining indoor units are stopped,
When the ratio of the number of indoor units performing heating operation among the plurality of indoor units is greater than a predetermined threshold,
Or
When the ratio of the total capacity of the indoor heat exchanger that the indoor unit performing the heating operation occupies with respect to the capacity of the outdoor heat exchanger is larger than a predetermined threshold,
While connecting the one end of the outdoor heat exchanger to the suction side of the compressor via the flow path switching means,
For the indoor unit that performs the heating operation, the first opening and closing means and the second opening and closing means are controlled so that the discharge side of the compressor and the indoor heat exchanger communicate with each other.
With respect to the stopped indoor unit, the first opening / closing means and the second opening / closing means are controlled so that the suction side of the compressor and the indoor heat exchanger communicate with each other, and the indoor unit has the indoor unit. The air conditioner according to claim 2, wherein the expansion valve is closed. The control means includes
In the case where the heating operation is performed in a part of the plurality of indoor units and the remaining indoor units are stopped,
When the ratio of the number of indoor units performing heating operation among the plurality of indoor units is equal to or less than a predetermined threshold,
Or
When the ratio of the total value of the capacity of the indoor heat exchanger that the indoor unit performing the heating operation occupies with respect to the capacity of the outdoor heat exchanger is equal to or less than a predetermined threshold value,
While connecting the one end of the outdoor heat exchanger to the suction side of the compressor via the flow path switching means,
For each of the indoor units, the first opening and closing means and the second opening and closing means are controlled so that the discharge side of the compressor and the indoor heat exchanger communicate with each other.
The air conditioner according to claim 2, wherein the indoor expansion valve of the stopped indoor unit is closed or slightly opened. The control means includes
When performing a cooling operation in a part of the plurality of indoor units and stopping the remaining indoor units,
When the ratio of the number of indoor units performing cooling operation among the plurality of indoor units is equal to or less than a predetermined threshold,
Or
When the ratio of the total value of the capacity of the indoor heat exchanger that the indoor unit performing the cooling operation occupies with respect to the capacity of the outdoor heat exchanger is equal to or less than a predetermined threshold value,
While connecting the one end of the outdoor heat exchanger to the suction side of the compressor via the flow path switching means,
For the indoor unit that performs the cooling operation, the first opening and closing means and the second opening and closing means are controlled so that the suction side of the compressor and the indoor heat exchanger communicate with each other.
For the stopped indoor unit, the first opening and closing means and the second opening and closing means are controlled so that the discharge side of the compressor and the indoor heat exchanger communicate with each other,
The air conditioner according to claim 2, further comprising closing the outdoor expansion valve.

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