JP2014214951A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of preventing degradation in cooling/heating capabilities resulting from insufficient refrigerant by eliminating refrigerant stagnation in an outdoor heat exchanger that is not used.SOLUTION: If refrigerant stagnation conditions are satisfied and a degree SHd of discharge overheat of a compressor 21b is not less than a first degree SH1 of discharge overheat while an air conditioner 1 performs a cooling-main operation, a CPU 110b determines that an opening of a second outdoor expansion valve 41b corresponding to a second outdoor heat exchanger 25b that is not used is a slight opening that is an opening at which a degree of refrigerant flowing in the second outdoor expansion valve 41b is the smallest and executes a cooling stagnation elimination control. If the degree SHd of discharge overheat of the compressor 21b is equal to a second discharge temperature lower than the first degree SH1 of discharge overheat, the refrigerant stagnation elimination conditions are satisfied, or an operation mode is switched to either a heating operation or a heating-main operation, the CPU 110b stops the cooling stagnation elimination control.

Description

  The present invention relates to an air conditioner in which at least one outdoor unit and a plurality of indoor units are connected by a plurality of refrigerant pipes. More specifically, the present invention eliminates refrigerant stagnation in an unused heat exchanger. The present invention relates to an air conditioner.

  Conventionally, air in which a plurality of indoor units are connected in parallel to at least one outdoor unit through a plurality of refrigerant pipes, and at the same time, a cooling operation and a heating operation can be performed for each indoor unit by selecting a cooling operation and a heating operation. Harmonic devices are known.

  For example, an air conditioner described in Patent Document 1 includes a compressor, an accumulator, two outdoor heat exchangers, an oil separator provided for each outdoor heat exchanger, a receiver tank, and each outdoor heat. One outdoor unit provided with an outdoor expansion valve, a discharge valve and a suction valve connected to the exchanger, two indoor units each provided with an indoor heat exchanger, and two electromagnetic valves And two solenoid valve units for switching the connection of the heat exchanger between the discharge side (high pressure side) and the suction side (low pressure side) of the compressor.

  These outdoor units, indoor units, and solenoid valve units are connected by refrigerant piping as follows. The discharge side of the compressor and the refrigerant inflow side of the oil separator are connected by a discharge pipe. Also, the refrigerant pipe connected to the refrigerant outlet side of the oil separator is branched, one is connected to the outdoor heat exchanger via the discharge valve, and the other is connected to the indoor heat exchanger via each solenoid valve unit. The The high-pressure gas pipe is composed of the discharge pipe and the refrigerant pipe described above.

  The suction side of the compressor and the refrigerant outflow side of the accumulator are connected by a suction pipe. Further, the refrigerant pipe connected to the refrigerant inflow side of the accumulator is branched, one is connected to the outdoor heat exchanger via the intake valve, and the other is connected to the indoor heat exchanger via each solenoid valve unit. . The suction pipe and the refrigerant pipe described above constitute a low pressure gas pipe.

  In each outdoor heat exchanger, a connection port opposite to a connection port to which a discharge valve or a suction valve is connected and one port of the outdoor expansion valve are connected by a refrigerant pipe. Further, the refrigerant pipe connected to the other port of the outdoor expansion valve merges and is connected to one refrigerant inlet / outlet of the receiver tank. The refrigerant pipe connected to the other refrigerant inlet / outlet of the receiver tank is branched and connected to a connection port opposite to the connection port to which the electromagnetic valve unit in each indoor heat exchanger is connected. Each refrigerant pipe described above constitutes a liquid pipe.

  In the air conditioner described above, each indoor heat exchanger is individually switched by switching the indoor heat exchanger to be connected to the discharge side or suction side of the compressor by opening and closing each solenoid valve of the solenoid valve unit. It can be made to function as a condenser or an evaporator, and at the same time, cooling operation or heating operation can be selected and performed for each indoor unit.

JP 2004-286253 A (pages 6-7, FIG. 1)

  In the above-described air conditioner, when all (two) indoor units perform cooling operation, or when one unit performs heating operation and the rest performs cooling operation, it is required for the indoor unit performing cooling operation. When the capacity is higher than the capacity required for the indoor unit performing the heating operation (hereinafter referred to as cooling main operation), various valves are controlled to open and close so that the outdoor heat exchanger functions as a condenser.

  If the outside air temperature is low when the air conditioner is performing a cooling operation or a cooling main operation, the condensation temperature is lowered and the high pressure is lowered, so that the cooling capacity and heating capacity of each indoor unit are lowered. In order to prevent this, it is necessary to increase the high pressure. However, if the rotational speed of the compressor is increased to the upper limit of the performance speed in order to increase the high pressure, the low pressure may decrease and become lower than the target low pressure. In addition, the condensation capacity of the indoor heat exchanger or outdoor heat exchanger functioning as a condenser is excessive with respect to the evaporation capacity of the indoor heat exchanger functioning as an evaporator, thereby reducing the condensation capacity. There may be a need.

  In such a case, a part of the outdoor heat exchanger functioning as a condenser is connected to the low-pressure side by switching the flow path switching means corresponding to the outdoor heat exchanger (evaporation). It is conceivable that the outdoor expansion valve corresponding to the outdoor heat exchanger is fully closed so that the outdoor heat exchanger does not function as a condenser. As described above, if an outdoor heat exchanger that is not functioning as a condenser (hereinafter referred to as an unused outdoor heat exchanger) is provided, the number of outdoor heat exchangers that function as a condenser is reduced. It is possible to reduce the condensing capacity or increase the low pressure by reducing the condensing capacity to approach the target low pressure.

  However, since the outdoor heat exchanger that is not used is connected to the low pressure side as described above, the outdoor heat exchanger that does not use a part of the refrigerant that has evaporated and returned to the outdoor unit in the indoor unit. Flows into and stays. At this time, when the outside air temperature decreases (for example, becomes −10 ° C.) and becomes lower than the low pressure saturation temperature, the refrigerant staying in the unused outdoor heat exchanger condenses and becomes a liquid refrigerant. There was a risk of falling asleep. And since a refrigerant | coolant stagnates in the outdoor heat exchanger which is not used, there existed a problem that the refrigerant | coolant circulation amount was insufficient in the refrigerant circuit of an air conditioning apparatus, and cooling capacity and heating capacity fell.

  The present invention solves the above-described problems, and eliminates refrigerant stagnation in unused outdoor heat exchangers, thereby preventing a decrease in cooling capacity or heating capacity due to insufficient refrigerant. The purpose is to provide.

  In order to solve the above problems, an air conditioner of the present invention is connected to one refrigerant inlet / outlet of each of at least one compressor, a plurality of outdoor heat exchangers, and an outdoor heat exchanger. The flow path switching means for switching the connection of the outdoor heat exchanger to the refrigerant discharge port or the refrigerant suction port and the other refrigerant inlet / outlet of each of the outdoor heat exchangers to adjust the refrigerant flow rate in the outdoor heat exchanger At least a flow rate adjusting means, an outside air temperature detecting means for detecting the outside air temperature, a low pressure detecting means for detecting the pressure on the low pressure side of the compressor, and a control means for controlling the flow path switching means and the flow rate adjusting means. One outdoor unit, a plurality of indoor units provided with an indoor heat exchanger, and a plurality of switching units provided corresponding to the plurality of indoor units and switching the flow direction of the refrigerant in the indoor heat exchanger And the outdoor unit Are connected by a high-pressure gas pipe and a low-pressure gas pipe, the plurality of indoor units are connected by at least one outdoor unit and a liquid pipe, and the corresponding plurality of indoor units and the plurality of switching units are refrigerant pipes. It is connected. The control means is connected to the low pressure side of the compressor by the outdoor heat exchanger functioning as a condenser and the flow path switching means, and the refrigerant is prevented from flowing by the flow rate adjusting means. When outdoor heat exchangers that do not function are mixed, and the outside air temperature detected by the outside air temperature detection means is lower than the low pressure saturation temperature calculated using the low pressure side pressure detected by the low pressure detection means When the state continues for a predetermined time, the refrigerant is allowed to flow to the outdoor heat exchanger that is not functioning as a condenser by the flow rate adjusting means.

  According to the air conditioner of the present invention configured as described above, when the air conditioner performs a cooling operation or a cooling main operation, the refrigerant stagnates in the outdoor heat exchanger that is not functioning as a condenser. If the refrigerant flows, the refrigerant is caused to flow by the flow rate adjusting means corresponding to the outdoor heat exchanger, so that the refrigerant that has fallen out flows out of the outdoor heat exchanger to the low pressure side and the refrigerant stagnation can be eliminated. it can. Thereby, the refrigerant shortage in each indoor unit can be solved, and a decrease in cooling capacity and heating capacity can be prevented.

It is explanatory drawing of the refrigerant circuit in the case of performing the cooling main driving | operation in embodiment of this invention. It is explanatory drawing of the refrigerant circuit in the case of using the outdoor heat exchanger which is not used in embodiment of this invention. It is explanatory drawing of a refrigerant circuit when performing refrigerant stagnation elimination control in embodiment of this invention. It is a flowchart explaining the process in a control means in embodiment of this invention.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. As an embodiment, an air conditioner in which five indoor units are connected in parallel to two outdoor units and can be operated by selecting a cooling operation and a heating operation for each indoor unit. An example will be described. The present invention is not limited to the following embodiments, and can be variously modified without departing from the gist of the present invention.

  As shown in FIG. 1, the air conditioner 1 in this embodiment includes two outdoor units 2a and 2b, five indoor units 8a to 8e, five switching units 6a to 6e, and a branching unit 70. , 71, 72. The outdoor units 2a and 2b, the indoor units 8a to 8e, the switching units 6a to 6e, the branching units 70, 71 and 72, the high pressure gas pipe 30, the high pressure gas branch pipes 30a and 30b, the low pressure gas pipe 31, and the low pressure The refrigerant circuit of the air conditioner 1 is comprised by mutually connecting with the gas distribution pipes 31a and 31b, the liquid pipe 32, and the liquid distribution pipes 32a and 32b.

  In the air conditioner 1, according to the open / closed state of various valves provided in the outdoor units 2a and 2b and the switching units 6a to 6e, heating operation (all indoor units are heating operation), heating main operation (heating operation is performed). If the overall capacity required for the indoor unit being used exceeds the overall capacity required for the indoor unit performing cooling operation), cooling operation (all indoor units are cooling operation), cooling-main operation (cooling operation In other words, it is possible to perform an operation such as when the entire capacity required for the indoor unit being performed exceeds the total capacity required for the indoor unit performing the heating operation. In the following description, the case where the cooling main operation is performed from among these operation operations will be described as an example and described with reference to FIG.

  FIG. 1 is a refrigerant circuit diagram in a case where the indoor units 8a to 8c are performing a cooling operation and the indoor units 8d and 8e are performing a heating operation. First, the outdoor units 2a and 2b will be described. Since the configurations of the outdoor units 2a and 2b are all the same, only the configuration of the outdoor unit 2a will be described in the following description, and a detailed description of the outdoor unit 2b will not be given. Omitted.

  As shown in FIG. 1, the outdoor unit 2a includes a compressor 21a, a first three-way valve 22a and a second three-way valve 23a that are flow path switching means, a first outdoor heat exchanger 24a, and a second outdoor heat exchange. 25a, outdoor fan 26a, accumulator 27a, oil separator 28a, receiver tank 29a, first outdoor expansion valve 40a connected to the first outdoor heat exchanger 24a, and second outdoor heat exchanger 25a. The connected second outdoor expansion valve 41a, the hot gas bypass pipe 36a, the first electromagnetic valve 42a provided in the hot gas bypass pipe 36a, the oil return pipe 37a, and the second provided in the oil return pipe 37a. An electromagnetic valve 43a and closing valves 44a to 46a are provided. The first outdoor expansion valve 40a and the second outdoor expansion valve 41a are the flow rate adjusting means in the present invention.

  The compressor 21a is a variable capacity compressor that can vary the operating capacity by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. As shown in FIG. 1, the discharge side of the compressor 21a is connected to the inflow side of the oil separator 28a by a refrigerant pipe, and the outflow side of the oil separator 28a is connected to the closing valve 44a by an outdoor unit high-pressure gas pipe 33a. ing. The suction side of the compressor 21a is connected to the outflow side of the accumulator 27a by a refrigerant pipe, and the inflow side of the accumulator 27a is connected to the closing valve 45a by an outdoor unit low-pressure gas pipe 34a.

  The first three-way valve 22a and the second three-way valve 23a are valves for switching the flow direction of the refrigerant. The first three-way valve 22a has three ports a, b, and c, and the second three-way valve 23a has d, Each of the three ports e and f is provided. In the first three-way valve 22a, the refrigerant pipe connected to the port a is connected to the outdoor unit high-pressure gas pipe 33a at the connection point A. The port b and the first outdoor heat exchanger 24a are connected by a refrigerant pipe, and the refrigerant pipe connected to the port c is connected to the outdoor unit low-pressure gas pipe 34a at a connection point D.

  In the second three-way valve 23a, the refrigerant pipe connected to the port d is connected at the connection point A to the refrigerant pipe connected to the outdoor unit high-pressure gas pipe 33a and the port a of the first three-way valve 22a. Further, the port e and the second outdoor heat exchanger 25a are connected by a refrigerant pipe, and the refrigerant pipe connected to the port f is connected to the refrigerant pipe connected to the port c of the first three-way valve 22a at the connection point C. Yes.

  The 1st outdoor heat exchanger 24a and the 2nd outdoor heat exchanger 25a are comprised by many fins (not shown) formed with the aluminum material, and several copper pipes (not shown) which distribute | circulate a refrigerant | coolant inside. As described above, one refrigerant inlet / outlet of the first outdoor heat exchanger 24a is connected to the port b of the first three-way valve 22a, and the other refrigerant inlet / outlet is connected to one port of the first outdoor expansion valve 40a via the refrigerant pipe. It is connected. The other port of the first outdoor expansion valve 40a is connected to the closing valve 46a via an outdoor unit liquid pipe 35a.

  As described above, one refrigerant inlet / outlet of the second outdoor heat exchanger 25a is connected to the port e of the second three-way valve 23a via the refrigerant pipe, and the other refrigerant inlet / outlet is connected to the second outdoor expansion valve 41a via the refrigerant pipe. Is connected to one of the ports. The other port of the second outdoor expansion valve 41a is connected to the outdoor unit liquid pipe 35a at the connection point B by a refrigerant pipe.

  The first outdoor expansion valve 40a and the second outdoor expansion valve 41a are electronic expansion valves that are driven by a pulse motor (not shown), and each opening degree is adjusted by the number of pulses applied to the pulse motor.

  The outdoor fan 26a is a propeller fan formed of a resin material disposed in the vicinity of the first outdoor heat exchanger 24a and the second outdoor heat exchanger 25a, and is rotated by a fan motor (not shown), so that the outdoor unit 2a The outside air is taken in and exchanged heat with the refrigerant in the first outdoor heat exchanger 24a and the second outdoor heat exchanger 25a, and then the heat-exchanged outdoor air is released to the outside of the outdoor unit 2a.

  As described above, the accumulator 27a has an inflow side connected to the outdoor unit low-pressure gas pipe 34a, and an outflow side connected to the suction side of the compressor 21a through a refrigerant pipe. The accumulator 27a separates the inflowing refrigerant into a gas refrigerant and a liquid refrigerant, and causes only the gas refrigerant to be sucked into the compressor 21a.

  As described above, the oil separator 28a has the inflow side connected to the discharge side of the compressor 21a by the refrigerant pipe and the outflow side connected to the outdoor unit high-pressure gas pipe 33a. The oil separator 28a separates the refrigerating machine oil of the compressor 21a included in the refrigerant discharged from the compressor 21a from the refrigerant. The separated refrigerating machine oil is sucked into the compressor 21a through an oil return pipe 37a described later.

  The receiver tank 29a is provided between the connection point B in the outdoor unit liquid pipe 35a and the closing valve 46a, and is a container capable of storing a refrigerant. The receiver tank 29a has a function of performing gas-liquid separation of the refrigerant, which serves as a buffer for adjusting the refrigerant amount inside the first outdoor heat exchanger 24a and the second outdoor heat exchanger 25a.

  One end of the hot gas bypass pipe 36a is connected to the outdoor unit high-pressure gas pipe 33a at a connection point E, and the other end is connected to the outdoor unit low-pressure gas pipe 34a at a connection point F. The hot gas bypass pipe 36a is provided with a first electromagnetic valve 42a. By opening and closing the first electromagnetic valve 42a, the hot gas bypass pipe 36a can be in a state where the refrigerant flows or does not flow.

  One end of the oil return pipe 37a is connected to the oil return port of the oil separator 28a, and the other end is connected to a refrigerant pipe connecting the suction side of the compressor 21a and the outflow side of the accumulator 27a at a connection point G. The oil return pipe 37a is provided with a second electromagnetic valve 43a. By opening and closing the second electromagnetic valve 43a, the oil return pipe 37a can be in a state where the refrigerant flows or does not flow.

  In addition to the configuration described above, the outdoor unit 2a is provided with various sensors. As shown in FIG. 1, a refrigerant pipe that connects the discharge side of the compressor 21a and the oil separator 28a includes a high-pressure sensor 50a that is a high-pressure detection means that detects the pressure of the refrigerant discharged from the compressor 21a, and a compression A discharge temperature sensor 53a, which is a discharge temperature detecting means for detecting the temperature of the refrigerant discharged from the machine 21a, is provided. Further, between the connection point F in the outdoor unit low-pressure gas pipe 34a and the inflow side of the accumulator 27a, a low-pressure sensor 51a which is a low-pressure detection means for detecting the pressure of refrigerant sucked into the compressor 21a, and the compressor 21a And a suction temperature sensor 54a for detecting the temperature of the refrigerant sucked. Further, between the connection point B in the outdoor unit liquid pipe 32a and the closing valve 46a, an intermediate pressure sensor 52a for detecting the pressure of the refrigerant flowing through the outdoor unit liquid pipe 35a and the temperature of the refrigerant flowing through the outdoor unit liquid pipe 35a. Is provided with a refrigerant temperature sensor 55a.

The refrigerant pipe connecting the port b of the first three-way valve 22a and the first outdoor heat exchanger 24a detects the temperature of the refrigerant flowing out of the first outdoor heat exchanger 24a or flowing into the first outdoor heat exchanger 24a. A first gas side refrigerant temperature sensor 56a is provided. A refrigerant pipe connecting the first outdoor heat exchanger 24a and the first outdoor expansion valve 40a detects the temperature of the refrigerant flowing out from the first outdoor heat exchanger 24a or flowing into the first outdoor heat exchanger 24a. A one-liquid-side refrigerant temperature sensor 59a is provided. The refrigerant pipe connecting the port e of the second three-way valve 23a and the second outdoor heat exchanger 25a detects the temperature of the refrigerant flowing out from the second outdoor heat exchanger 25a or flowing into the second outdoor heat exchanger 25a. A second gas side refrigerant temperature sensor 57a is provided. A refrigerant pipe that connects the second outdoor heat exchanger 25a and the second outdoor expansion valve 41a detects the temperature of the refrigerant that flows out of the second outdoor heat exchanger 25a or flows into the second outdoor heat exchanger 25a. A two-liquid-side refrigerant temperature sensor 60a is provided.
An outdoor temperature sensor 58a, which is an outside air temperature detecting means for detecting the outside air temperature flowing into the outdoor unit 2a, is provided in the vicinity of a suction port (not shown) of the outdoor unit 2a.

  The outdoor unit 2a is provided with a control means 100a. The control unit 100a is mounted on a control board (not shown) and includes a CPU 110a, a storage unit 120a, and a communication unit 130a. CPU110a takes in the detection signal from each sensor mentioned above of outdoor unit 2a, and takes in the control signal output from each indoor unit 8a-8e via communication part 130a. The CPU 110a controls the drive control of the compressor 21a, the switching control of the first three-way valve 22a and the second three-way valve 23a, the rotation control of the fan motor 29a, the first outdoor expansion valve 40a and the first based on the acquired detection signal and control signal. Various controls such as the opening degree control of the two outdoor expansion valves 41a are performed.

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

  The configuration of the outdoor unit 2b is the same as that of the outdoor unit 2a, and the number assigned to the components (devices and members) of the outdoor unit 2a is changed from a to b. It becomes a component of the corresponding outdoor unit 2b. However, the symbols for the connection points of the first three-way valve, the second three-way valve, and the refrigerant pipe are different between the outdoor unit 2a and the outdoor unit 2b, and the port a in the first three-way valve 22a of the outdoor unit 2a. , B, c are ports g, h, j in the first three-way valve 22b of the outdoor unit 2b, and those corresponding to ports d, e, f in the second three-way valve 23a of the outdoor unit 2a are the outdoor units. In the 2b second three-way valve 23b, ports k, m, and n are set. In the outdoor unit 2b, the connection points H, J, K, M, N, P, and Q correspond to the connection points A, B, C, D, E, F, and G in the outdoor unit 2a.

  The five indoor units 8a to 8e include indoor heat exchangers 81a to 81e, indoor expansion valves 82a to 82e, and indoor fans 83a to 83e. In addition, since the structure of all the indoor units 8a-8e is the same, in the following description, only the structure of the indoor unit 8a is demonstrated, and description is abbreviate | omitted about the other indoor units 8b-8e.

  One end of the indoor heat exchanger 81a is connected to one port of the indoor expansion valve 82a via a refrigerant pipe, and the other end is connected to a switching unit 6a described later via a refrigerant pipe. The indoor heat exchanger 81a functions as an evaporator when the indoor unit 8a performs a cooling operation, and functions as a condenser when the indoor unit 8a performs a heating operation.

  The indoor expansion valve 82a is an electronic expansion valve driven by a pulse motor (not shown), and the opening degree is adjusted by the number of pulses applied to the pulse motor. The indoor expansion valve 82 a has one port connected to the indoor heat exchanger 81 a as described above, and the other port connected to the liquid pipe 32. When the indoor heat exchanger 81a functions as an evaporator, the indoor expansion valve 82a is adjusted according to the required cooling capacity, and when the indoor heat exchanger 81a functions as a condenser, The opening is adjusted according to the required heating capacity.

  The indoor fan 83a is rotated by a fan motor (not shown), thereby taking in indoor air into the indoor unit 8a, heat-exchanging the refrigerant and indoor air in the indoor heat exchanger 81a, and then transferring the heat-exchanged air indoors. Supply.

  In addition to the configuration described above, the indoor unit 8a is provided with various sensors. A refrigerant temperature sensor 84a for detecting the refrigerant temperature is detected in the refrigerant pipe on the indoor expansion valve 82a side of the indoor heat exchanger 81a, and a refrigerant temperature is detected in the refrigerant pipe on the switching unit 6a side of the indoor heat exchanger 81a. Refrigerant temperature sensors 85a are provided. Further, a room temperature sensor 86a for detecting the temperature of the indoor air flowing into the indoor unit 8a, that is, the room temperature is provided in the vicinity of the indoor air suction port (not shown) of the indoor unit 8a.

  The configurations of the indoor units 8b to 8e are the same as those of the indoor unit 8a, and the numbers given to the constituent elements (devices and members) of the indoor unit 8a are changed from a to b, c, d, and e, respectively. However, it becomes a component of the indoor units 8b-8e corresponding to the component of the outdoor unit 8a.

  The air conditioner 1 includes five switching units 6a to 6e corresponding to the five indoor units 8a to 8e. The switching units 6a to 6e include solenoid valves 61a to 61e, solenoid valves 62a to 62e, first branch pipes 63a to 63e, and second branch pipes 64a to 64e. In addition, since all the structures of switching unit 6a-6e are the same, in the following description, only the structure of switching unit 6a is demonstrated and description is abbreviate | omitted about the other switching units 6b-6e.

  One end of the first branch pipe 63 a is connected to the high pressure gas pipe 30, and one end of the second branch pipe 64 a is connected to the low pressure gas pipe 31. Further, the other end of the first diversion pipe 63a and the other end of the second diversion pipe 64a are connected to each other, and the connection portion and the indoor heat exchanger 81a are connected by a refrigerant pipe. The first diverter pipe 63a is provided with an electromagnetic valve 61a, and the second diverter pipe 64a is provided with an electromagnetic valve 62a. By opening and closing the electromagnetic valve 61a and the electromagnetic valve 62a, the switching unit 6a is provided. The refrigerant flow path in the refrigerant circuit is switched so that the indoor heat exchanger 81a of the corresponding indoor unit 8a 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. be able to.

  Note that the configuration of the switching units 6b to 6e is the same as that of the switching unit 6a as described above, and the end of the numbers given to the components (devices and members) of the switching unit 6a are a to b, c, d and e. Those changed to the above are the constituent elements of the switching units 6b to 6e corresponding to the constituent elements of the switching unit 6a.

  The outdoor units 2a and 2b, the indoor units 8a to 8e and the switching units 6a to 6e described above, the high pressure gas pipe 30, the high pressure gas distribution pipes 30a and 30b, the low pressure gas pipe 31, the low pressure gas distribution pipes 31a and 31b, the liquid pipe 32, The connection state with the liquid distribution pipes 32a and 32b and the branching devices 70, 71, and 72 will be described with reference to FIG. One end of the high-pressure gas branch pipes 30a and 30b is connected to the shut-off valves 44a and 44b of the outdoor units 2a and 2b, respectively, and the other end of the high-pressure gas branch pipes 30a and 30b is connected to the branch device 70, respectively. One end of the high-pressure gas pipe 30 is connected to the branching device 70, and the other end of the high-pressure gas pipe 30 is branched and connected to the first branch pipes 63a to 63e of the switching units 6a to 6e.

  One ends of the low-pressure gas distribution pipes 31a and 31b are connected to the shut-off valves 45a and 45b of the outdoor units 2a and 2b, respectively, and the other ends of the low-pressure gas distribution pipes 31a and 31b are connected to the branch device 71, respectively. One end of the low-pressure gas pipe 31 is connected to the branching device 71, and the other end of the low-pressure gas pipe 31 is branched and connected to the second branch pipes 64a to 64e of the switching units 6a to 6e.

  One ends of the liquid distribution pipes 32a and 32b are connected to the closing valves 46a and 46b of the outdoor units 2a and 2b, respectively, and the other ends of the liquid distribution pipes 32a and 32b are connected to the branching device 72, respectively. One end of the liquid pipe 32 is connected to the branching device 72, and the other end of the liquid pipe 32 is branched and connected to refrigerant pipes connected to the indoor expansion valves 82a to 82e of the indoor units 8a to 8e, respectively.

The connection points of the indoor heat exchangers 81a to 81e of the corresponding indoor units 8a to 8e and the first branch pipes 63a to 63e and the second branch pipes 64a to 64e in the switching units 6a to 6e are refrigerant pipes, respectively. Connected.
With the connection described above, the refrigerant circuit of the air conditioner 1 is configured, and the refrigeration cycle is established by flowing the refrigerant through the refrigerant circuit.

  Next, the operation | movement operation | movement of the air conditioning apparatus 1 in a present Example is demonstrated using FIG. In addition, in FIG. 1, when each heat exchanger with which the outdoor units 2a and 2b and indoor unit 8a-8e were equipped becomes a condenser, hatching is attached | subjected, and when it becomes an evaporator, it illustrates in white. Further, the first electromagnetic valves 42a and 42b and the second electromagnetic valves 43a and 43b provided in the outdoor units 2a and 2b, and the electromagnetic valves 61a to 61e and the electromagnetic valves 62a to 62e provided in the switching units 6a to 6e are opened and closed. As for the state, the closed state is illustrated in black, and the open state is illustrated in white. Ports that communicate with each other in three-way valves are indicated by solid lines, and ports that do not communicate with each other are indicated by broken lines. Moreover, the arrow has shown the flow of the refrigerant | coolant.

  As shown in FIG. 1, the indoor units 8a to 8c perform cooling operation, the indoor units 8d and 8e perform heating operation, and the operation capability (cooling capability) required by the indoor units 8a to 8c is required by the indoor units 8d and 8e. When the operation capacity (heating capacity) is larger than the above, the air conditioner 1 performs the cooling main operation. At this time, in the outdoor unit 2a, the port a and the port b of the first three-way valve 22a are switched to communicate with each other, and the first outdoor heat exchanger 24a functions as a condenser, and the port d of the second three-way valve 23a and The second outdoor heat exchanger 25a functions as a condenser by switching to communicate with the port e. In the outdoor unit 2b, the port g and the port h of the first three-way valve 22b are switched so as to communicate with each other, the first outdoor heat exchanger 24b functions as a condenser, and the port k and the port of the second three-way valve 23b. The second outdoor heat exchanger 25b functions as a condenser by switching so as to communicate with m. The first electromagnetic valves 42a and 42b and the second electromagnetic valves 43a and 43b of the outdoor units 2a and 2b are both closed, and the hot gas bypass pipes 36a and 36b and the oil return pipes 37a and 37b are made of refrigerant or Refrigerating machine oil is not allowed to flow.

  In the indoor units 8a to 8c that perform the cooling operation, the electromagnetic valves 61a to 61c of the switching units 6a to 6c corresponding thereto are closed to prevent the refrigerant from flowing through the first branch pipes 63a to 63c, and the electromagnetic valves 62a to 62c. 62c is opened so that the refrigerant flows through the second branch pipes 64a to 64c. Thereby, all the indoor heat exchangers 81a to 81c of the indoor units 8a to 8c function as an evaporator.

  On the other hand, in the indoor units 8d and 8e that perform the heating operation, the solenoid valves 61d and 61e of the switching units 6d and 6e corresponding to the respective indoor units 8d and 8e are opened so that the refrigerant flows through the first branch pipes 63d and 63e. , 62e are closed to prevent the refrigerant from flowing through the second branch pipes 64d, 64e. Thereby, all the indoor heat exchangers 81d and 81e of the indoor units 8d and 8e function as a condenser.

  The high-pressure refrigerant discharged from the compressors 21a and 21b flows through the outdoor unit high-pressure gas pipes 33a and 33b via the oil separators 28a and 28b, and at the connection points A and H, the first three-way valves 22a and 22b side and the second The flow is diverted to the three-way valves 23a and 23b and to the closing valves 44a and 44b.

  The refrigerant that has passed through the first three-way valves 22a and 22b and the second three-way valves 23a and 23b and has flowed into the first outdoor heat exchangers 24a and 24b and the second outdoor heat exchangers 25a and 25b passes through the outdoor fans 26a and 26b. Heat is exchanged with the outside air that has flowed into the outdoor units 2a and 2b by the rotation to condense. The refrigerant condensed in the first outdoor heat exchangers 24a and 24b and the second outdoor heat exchangers 25a and 25b is transferred to the first outdoor heat exchangers 24a and 24b and the second outdoor heat exchangers 25a and 25b by the CPUs 110a and 110b. The refrigerant passes through the first outdoor expansion valves 40a and 40b and the second outdoor expansion valves 41a and 41b whose opening degree is such that the degree of refrigerant supercooling at the outlet becomes a predetermined target value, and becomes an intermediate pressure refrigerant. The refrigerant supercooling degree is calculated by, for example, a high pressure saturation temperature calculated using pressure detected by the high pressure sensors 50a and 50b (condensation in the first outdoor heat exchangers 24a and 24b and the second outdoor heat exchangers 25a and 25b). It is obtained by subtracting the refrigerant temperature detected by the first liquid side refrigerant temperature sensors 59a, 59b and the second liquid side refrigerant temperature sensors 60a, 60b from the temperature).

  The refrigerant that has passed through the first outdoor expansion valves 40a and 40b and the second outdoor expansion valves 41a and 41b merges at the connection points B and J, flows through the outdoor unit liquid pipes 35a and 35b, and passes through the closing valves 46a and 46b. It flows through the liquid distribution pipes 32a and 32b, joins at the branching device 72, and flows from the liquid pipe 32 into the indoor units 8a to 8c.

  The refrigerant that has flowed into the indoor units 8a to 8c is depressurized by the indoor expansion valves 82a to 82c, becomes a low-pressure refrigerant, and flows into the indoor heat exchangers 81a to 81c. The refrigerant flowing into the indoor heat exchangers 81a to 81c evaporates by exchanging heat with the indoor air flowing into the indoor units 8a to 8c by the rotation of the indoor fans 83a to 83c. As a result, the cooled indoor air flows into the room through a blower outlet (not shown), and the room where the indoor units 8a to 8c are installed is cooled. In addition, the opening degree of the indoor expansion valves 82a to 82c is determined in accordance with the degree of superheat of the refrigerant at the refrigerant outlet of the indoor heat exchangers 81a to 81c, and the degree of superheat of the refrigerant is taken from, for example, refrigerant temperature sensors 85a to 85c. It is obtained by subtracting the refrigerant temperature at the refrigerant inlet of the indoor heat exchangers 81a to 81c taken from the refrigerant temperature sensors 84a to 84c from the refrigerant temperature at the refrigerant outlet of the indoor heat exchangers 81a to 81c.

  The refrigerant that has flowed out of the indoor heat exchangers 81a to 81c flows into the switching units 6a to 6c and flows through the second branch pipes 64a to 64c provided with the open electromagnetic valves 62a to 62c to the low pressure gas pipe 31. Inflow. The refrigerant flowing through the low-pressure gas pipe 31 and flowing into the branching device 71 is branched from the branching device 71 into the low-pressure gas distribution tubes 31a and 31b, and flows into the outdoor units 2a and 2b through the closing valves 45a and 45b. The refrigerant flowing into the outdoor units 2a and 2b flows through the outdoor unit low-pressure gas pipes 34a and 34b, is sucked into the compressors 21a and 21b via the accumulators 27a and 27b, and is compressed again.

  On the other hand, the high-pressure refrigerant that flows from the connection points A and H to the outdoor unit high-pressure gas pipes 33a and 33b and flows into the high-pressure gas branch pipes 30a and 30b through the shut-off valves 44a and 44b is merged in the branching unit 70. It flows through the pipe 30 and flows from the high-pressure gas pipe 30 into the switching units 6d and 6e.

  The high-pressure refrigerant that has flowed into the switching units 6d and 6e flows through the first branch pipes 63d and 63e provided with the open electromagnetic valves 61d and 61e, and flows out of the switching units 6d and 6e. It flows into the indoor units 8d and 8e corresponding to 6e. The high-pressure refrigerant that has flowed into the indoor units 8d and 8e flows into the indoor heat exchangers 81d and 81e, and is condensed by exchanging heat with the indoor air that has flowed into the indoor units 8d and 8e by the rotation of the indoor fans 83d and 83e. To do. Thereby, the indoor air heated by this flows out into the room from the blower outlet which is not illustrated, and the indoor in which indoor unit 8d, 8e was installed is heated.

The high-pressure refrigerant that has flowed out of the indoor heat exchangers 81d and 81e passes through the indoor expansion valves 82d and 82e and is depressurized. The opening degree of the indoor expansion valves 82d and 82e is determined according to the degree of supercooling of the refrigerant at the refrigerant outlet of the indoor heat exchangers 81d and 81e. The degree of supercooling of the refrigerant is, for example, from a high-pressure saturation temperature (corresponding to the condensation temperature in the indoor heat exchangers 81d and 81e) calculated from the pressure detected by the high-pressure sensors 50a and 50b of the outdoor units 2a and 2b. It is obtained by subtracting the refrigerant temperature at the refrigerant outlet of the indoor heat exchangers 81d and 81e detected by 84d and 84e.
The refrigerant that has passed through the indoor expansion valves 82d and 82e and has flowed out of the indoor units 8d and 8e flows through the liquid pipe 32 and flows into the indoor units 8a to 8c performing the cooling operation.

  Next, with reference to FIGS. 1 to 4, the operation of the refrigerant circuit according to the present invention and the operation and effect thereof in the air-conditioning apparatus 1 of the present embodiment will be described. First, the reason why refrigerant stagnation occurs in an outdoor heat exchanger that is not used in the air-conditioning apparatus 1 that is performing a cooling main operation will be described with reference to FIG.

  FIG. 2 shows a state in which the refrigerant circuit is switched so that the second outdoor heat exchanger 25b of the outdoor unit 2b is not used when the air conditioner 1 performs the cooling main operation shown in FIG. . Specifically, the second outdoor heat exchanger 25b is connected to the low pressure side (outdoor unit low pressure gas pipe 34b) by switching so that the port m and the port n of the second three-way valve 23b communicate with each other. The expansion valve 41b is fully closed (blacked in FIG. 2).

  As described above, when the second outdoor heat exchanger 25b of the outdoor unit 2b is not used, for example, as described in the background art, in order to increase the high pressure in a state where the outdoor temperature is low, the compressor In order to raise the low pressure reduced by raising the rotation speed of 21a and 21b to the upper limit rotation speed to the target low pressure, the condensation capacity is lowered by reducing the number of outdoor heat exchangers functioning as condensers. The indoor heat exchangers 81d and 81e functioning as condensers and the first outdoor heat exchanger for evaporating capacity of the indoor heat exchangers 81a to 81c functioning as evaporators when raising the low pressure. There are cases where the condensing capacity in 24a, 24b and the second outdoor heat exchangers 25a, 25b becomes excessive and the condensing capacity needs to be reduced.

  When the refrigerant circuit of the air conditioner 1 is in the state shown in FIG. 2, a part of the refrigerant that flows into the outdoor unit 2b from the low pressure gas distribution pipe 31b and flows through the outdoor unit low pressure gas pipe 34b from the connection point M The air is diverted to the second three-way valve 23b side and flows into the second outdoor heat exchanger 25b (shown by broken line arrows in FIG. 2). The refrigerant flowing into the second outdoor heat exchanger 25b stays in the second outdoor heat exchanger 25b because the second outdoor expansion valve 41b is fully closed.

  At this time, it was detected by the outside air temperature sensors 58a and 58b from the low pressure saturation temperature Ts calculated from the pressure detected by the low pressure sensors 51a and 51b (corresponding to the evaporation temperature in the indoor heat exchangers 81a to 81c functioning as an evaporator). A state in which the outside air temperature To is low and the operating capacity of the compressors 21a and 21b cannot be increased (for example, the rotational speed of the compressors 21a and 21b is increased to the upper limit performance speed as described above), that is, a low pressure When the low-pressure saturation temperature Ts cannot be lowered because the pressure cannot be lowered (hereinafter, this condition is referred to as the refrigerant stagnation generation condition), the refrigerant staying in the second outdoor heat exchanger 25b is condensed. As a result, the liquid refrigerant may fall into the second outdoor heat exchanger 25b.

  When such a state continues for a long time and the amount of refrigerant stagnation in the second outdoor heat exchanger 25b that is not used increases, the amount of refrigerant circulating in the refrigerant circuit decreases and the amount of refrigerant flowing to the indoor units 8a to 8e decreases. And there existed a possibility that the air_conditioning | cooling capability and heating capability in indoor unit 8a-8e may fall.

  Therefore, the air conditioner 1 of the present invention is shown in FIG. 3 if the refrigerant stagnation generation condition is satisfied when the cooling operation or the cooling main operation is performed in the presence of the outdoor heat exchanger that is not used. Thus, the refrigerant sleeping in the unused second outdoor heat exchanger 25 by opening the second outdoor expansion valve 41b with the second three-way valve 23b as it is (the state where the port m and the port n communicate with each other). The refrigerant stagnation elimination control for causing the refrigerant to flow out to the accumulator 27b side is executed.

  The refrigerant stagnation elimination control will be specifically described below with reference to FIGS. 1 to 4. The flowchart shown in FIG. 4 shows the flow of processing when refrigerant stagnation elimination control is performed, ST represents a step, and the number following this represents a step number. In FIG. 4, the processing related to the present invention is mainly described, and other general processing such as control of the refrigerant circuit corresponding to the operating conditions such as the set temperature and the air volume instructed by the user is described. Is omitted.

  First, the CPUs 110a and 110b determine whether or not the air conditioner 1 is performing a cooling operation or a cooling main operation (ST1). When the cooling operation or the cooling main operation is not performed (ST1-No), the CPUs 110a and 110b end the processing. When the cooling operation or the cooling main operation is performed (ST1-Yes), the CPUs 110a and 110b determine whether there is an outdoor heat exchanger that is not used (ST2).

  When there is no outdoor heat exchanger that is not used (all outdoor heat exchangers are used) (ST2-No), the refrigerant circuit of the air conditioner 1 is in the state shown in FIG. 110b controls each component of the outdoor units 2a and 2b as described above to continue the cooling operation or the cooling main operation, and returns the process to ST1.

  When there is an outdoor heat exchanger that is not used (ST2-Yes), the refrigerant circuit of the air conditioner 1 is in the state shown in FIG. 2, for example. Specifically, in the outdoor unit 2a, the first three-way valve 22a is switched so that the port a and the port b communicate, and the second three-way valve 23a communicates with the port d and the port e. It has been switched (state shown by a solid line in FIG. 2). Thereby, the 1st outdoor heat exchanger 24a and the 2nd outdoor heat exchanger 25a function as a condenser.

  In the outdoor unit 2b, the first three-way valve 22b is switched so that the port g and the port h communicate with each other, and the second three-way valve 23b is switched so that the port m and the port n communicate with each other. (The state shown by the solid line in FIG. 2). Thereby, the 1st outdoor heat exchanger 24b functions as a condenser.

  In the refrigerant circuit described above, the CPU 110a drives the compressor 21a at a rotation speed corresponding to the required driving capability, and changes the opening degrees of the first outdoor expansion valve 40a and the second outdoor expansion valve 41a to the first outdoor heat exchange. It is set as the opening according to the refrigerant | coolant supercooling degree in the exit of the container 24a and the 2nd outdoor heat exchanger 25a. In addition, the CPU 110b drives the compressor 21b at a rotation speed corresponding to the required operating capacity, and sets the opening degree of the first outdoor expansion valve 40b of the first outdoor heat exchanger 40b and the second outdoor heat exchanger 41b. The opening is determined according to the degree of refrigerant supercooling at the outlet. Further, the second outdoor expansion valve 41b is fully closed so that the second outdoor heat exchanger 25b is not used.

  The CPUs 110a and 110b perform the cooling main operation by controlling the outdoor units 2a and 2b as described above. As described above, the refrigerant supercooling degree is calculated based on the high pressure saturation temperature calculated using the pressure detected by the high pressure sensors 50a and 50b, and the first liquid side refrigerant temperature sensors 59a and 59b and the second liquid side refrigerant temperature sensor 60a. The CPU 110a, 110b obtains the refrigerant subcooling degree periodically (for example, every 30 seconds) to obtain the first outdoor expansion valves 40a, 40b and the second outdoor expansion. The opening degree of the valve 41a is adjusted.

  Next, the CPUs 110a and 110b take in the outside air temperature To detected by the outside air temperature sensors 58a and 58b (ST3), take in the pressure detected by the low pressure sensors 51a and 51b, and set the low pressure saturation temperature Ts using the taken in pressure. Calculate (ST4). The CPUs 110a and 110b periodically take in the outside air temperature To and calculate the low-pressure saturation temperature Ts (for example, every 5 seconds).

  Next, the CPU 110b of the outdoor unit 2b including the outdoor heat exchanger that is not used determines whether or not the refrigerant stagnation generation condition is satisfied (ST5). Here, the refrigerant stagnation generation condition indicates a condition in which the refrigerant stagnation may occur in the second outdoor heat exchanger 25b that is not used. Specific examples of conditions are as described above. The state in which the outside air temperature To taken in is lower than the calculated low pressure saturation temperature Ts and the operating capacity of the compressors 21a and 21b cannot be increased is a predetermined time or more after the outside air temperature To becomes lower than the low pressure saturation temperature Ts. For example, whether it has continued for 10 minutes or more.

  When the refrigerant stagnation generation condition is not satisfied (ST5-No), the CPU 110b returns the process to ST1. When the refrigerant stagnation generation condition is satisfied (ST5-Yes), the CPU 110b subtracts the high-pressure saturation temperature calculated using the high pressure detected by the high-pressure sensor 50b from the discharge temperature detected by the discharge temperature sensor 53b. Thus, the discharge superheat degree SHd of the compressor 21b is calculated (ST6).

  Next, the CPU 110b determines whether or not the calculated discharge superheat degree SHd is equal to or greater than a predetermined first discharge superheat degree SH1 (ST7). If the discharge superheat degree SHd is equal to or greater than the predetermined first discharge superheat degree SH1 (ST7-Yes), the CPU 110b maintains the state in which the port m and the port n of the second three-way valve 23b are in communication with each other. Refrigerant stagnation elimination control is executed to slightly open the valve 41b (the minimum opening degree at which refrigerant flows) (ST8).

  Thereby, since the refrigerant in the gas-liquid two-phase state flows into the second outdoor heat exchanger 25b from the connection point J through the second outdoor expansion valve 41b, the liquid refrigerant staying in the second outdoor heat exchanger 25b. Flows out from the second outdoor heat exchanger 25b and is sucked into the compressor 21b via the second three-way valve 23b and the accumulator 27b, so that the amount of refrigerant stagnation in the second outdoor heat exchanger 25b is reduced, and the refrigerant circuit Increases the amount of refrigerant circulating in The second outdoor expansion valve 41b is slightly opened because a large amount of liquid refrigerant flows into the accumulator 27b when the second outdoor expansion valve 41b is opened widely, and the liquid refrigerant overflows in the accumulator 27b. This is to prevent so-called liquid back where the liquid refrigerant is sucked into the compressor 21b.

  Next, CPU 110b determines whether or not the refrigerant stagnation elimination condition is satisfied (ST9). Here, the refrigerant stagnation elimination condition indicates a condition in which the refrigerant stagnation does not occur in the outdoor heat exchanger even when there is an outdoor heat exchanger that is not used. Whether or not the temperature obtained by subtracting a predetermined temperature (for example, 2 ° C., which is previously obtained by a test or the like and stored in the outdoor unit control units 100a and 100b) from To is higher than the low-pressure saturation temperature Ts. . Here, the temperature obtained by subtracting a predetermined temperature from the outside air temperature To is compared with the low-pressure saturation temperature Ts, but this is compared with the outside-air temperature To and the low-pressure saturation temperature Ts in the refrigerant stagnation elimination condition. This is to prevent frequent occurrence of the refrigerant stagnation generation condition being satisfied again and the refrigerant stagnation elimination control being executed immediately after the cancellation control is stopped.

  If the refrigerant stagnation elimination condition is not satisfied (ST9-No), the CPU 110b returns the process to ST1. If the refrigerant stagnation elimination condition is satisfied (ST9-Yes), the CPU 110b fully closes the second outdoor expansion valve 41b and stops the refrigerant stagnation elimination control (ST10).

  If the discharge superheat degree SHd is not equal to or greater than the predetermined first discharge superheat degree SH1 in ST7 (ST7-No), the CPU 110b determines whether or not the refrigerant stagnation elimination control is being executed (ST12). If the refrigerant stagnation elimination control is not being executed (ST12-No), the CPU 110b returns the process to ST1. If the refrigerant stagnation elimination control is being executed (ST12-Yes), the CPU 110b determines whether or not the discharge superheat degree SHd is equal to or less than a predetermined second discharge superheat degree SH2 that is smaller than the first discharge superheat degree SH1. (ST13).

  If the discharge superheat degree SHd is not less than or equal to the second discharge superheat degree SH2 (ST13-No), the CPU 110b proceeds to ST8 to continue the refrigerant stagnation elimination control, and the discharge superheat degree SHd is the second discharge superheat degree SH2. If it is below (ST13-Yes), the CPU 110b advances the process to ST10 and stops the refrigerant stagnation elimination control.

  Here, the reason why execution / continuation or stop of the refrigerant stagnation elimination control is determined based on the first discharge superheat degree SH1 and the second discharge superheat degree SH2 will be described. In the refrigerant stagnation elimination control described above, by opening the closed second outdoor expansion valve 41b, the liquid refrigerant sleeping in the second outdoor heat exchanger 25b is caused to flow out to the accumulator 27b side. If a large amount of liquid refrigerant flows out of the second outdoor heat exchanger 25b, an overflow may occur in the accumulator 27b and a so-called liquid back may occur in which the liquid refrigerant is sucked into the compressor 21b.

  If the liquid back is generated, the discharge temperature of the compressor 21b is lowered, so that the discharge superheat degree SHd of the compressor 21b is reduced. From this, it is considered that the possibility that the liquid back is generated decreases as the discharge superheat degree SHd of the compressor 21b increases.

  In the present embodiment, in consideration of the above description, it is considered that there is no occurrence of liquid back even if the liquid refrigerant sleeping in the second outdoor heat exchanger 25 is caused to flow by opening the second outdoor expansion valve 41b. A first discharge superheat degree SH1 (for example, 8K) is set as the discharge superheat degree SHd of the compressor 21b. Further, when the second outdoor expansion valve 41b is opened and the liquid refrigerant sleeping in the second outdoor heat exchanger 25 is caused to flow out, it is considered that there is a possibility of liquid back, and the first discharge superheat degree SHd of the compressor 21b is assumed to be the first. A second discharge superheat degree SH2 (for example, 4K) lower than the discharge superheat degree is set. The reason why the first discharge superheat degree SH1 and the second discharge superheat degree SH2 are made different is to prevent the execution / stop of the refrigerant stagnation elimination control from being frequently switched.

  In ST10, the CPU 110a and the CPU 110b that has stopped the refrigerant stagnation elimination control determine whether or not all the indoor units 8a to 8e are stopped and the outdoor units 2a and 2b are ended (ST11). If the operation is finished (ST11-Yes), the CPUs 110a and 110b finish the process. If the operation is not finished (ST11-No), the CPUs 110a and 110b return the process to ST1.

  As described above, according to the air conditioner of the present invention, when the air conditioner performs the cooling operation or the cooling main operation, the refrigerant stagnates in the outdoor heat exchanger that is not functioning as a condenser. If the refrigerant flows, the refrigerant is caused to flow by the flow rate adjusting means corresponding to the outdoor heat exchanger, so that the refrigerant that has fallen out flows out of the outdoor heat exchanger to the low pressure side and the refrigerant stagnation can be eliminated. it can. Thereby, the refrigerant shortage in each indoor unit can be solved, and a decrease in cooling capacity and heating capacity can be prevented.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2a, 2b Outdoor unit 6a-6e Switching unit 8a-8e Indoor unit 21a, 21b Compressor 22a, 22b 1st three-way valve 23a, 23b 2nd three-way valve 24a, 24b 1st outdoor heat exchanger 25a, 25b 2nd outdoor heat exchanger 40a, 40b 1st outdoor expansion valve 41a, 41b 2nd outdoor expansion valve 50a, 50b High pressure sensor 51a, 51b Low pressure sensor 53a, 53b Discharge temperature sensor 58a, 58b Outside air temperature sensor 81a-81e Indoor heat exchange Device 100a, 100b Control means 110a, 110b CPU
To outside air temperature Ts low pressure saturation temperature SHd discharge superheat degree SH1 first discharge superheat degree SH2 second discharge superheat degree

Claims (3)

At least one compressor, a plurality of outdoor heat exchangers, and the outdoor heat exchanger connected to one refrigerant inlet / outlet of each of the outdoor heat exchangers to the refrigerant discharge port or the refrigerant suction port of the compressor A flow path switching means for switching the connection, a flow rate adjusting means for adjusting the flow rate of refrigerant in the outdoor heat exchanger connected to the other refrigerant inlet / outlet of each of the outdoor heat exchangers, and an outside air temperature for detecting the outside air temperature At least one outdoor unit comprising detection means, low pressure detection means for detecting the pressure on the low pressure side of the compressor, and control means for controlling the flow path switching means and the flow rate adjustment means;
A plurality of indoor units equipped with indoor heat exchangers;
A plurality of switching units provided corresponding to the plurality of indoor units and switching the flow direction of the refrigerant in the indoor heat exchanger, wherein the outdoor unit and the plurality of switching units are a high-pressure gas pipe and a low-pressure gas pipe. A plurality of the indoor units are connected to at least one of the outdoor units by a liquid pipe, and the corresponding plurality of the indoor units and the plurality of switching units are connected by a refrigerant pipe. And
The control means is connected to the outdoor heat exchanger functioning as a condenser and the low-pressure side of the compressor by the flow path switching means, and prevents the refrigerant from flowing by the flow rate adjusting means. When the outdoor heat exchanger that does not function as a condenser is mixed, the outside air temperature detected by the outside air temperature detecting means is calculated using the low pressure side pressure detected by the low pressure detecting means. When the state lower than the low-pressure saturation temperature continues for a predetermined time, the air conditioner causes the refrigerant to flow through the outdoor heat exchanger that is not functioning as a condenser by the flow rate adjusting means. . The flow rate adjusting means is an expansion valve;
The outdoor unit includes a high-pressure detection unit that detects a pressure on a high-pressure side of the compressor, and a discharge temperature detection unit that detects a refrigerant temperature discharged from the compressor.
The control means includes
Obtaining the discharge superheat degree of the compressor from the refrigerant temperature detected by the discharge temperature detection means and the pressure on the high pressure side detected by the high pressure detection means,
When the discharge superheat degree is equal to or higher than a predetermined first discharge superheat degree, the expansion valve corresponding to the outdoor heat exchanger that is not functioning as a condenser is opened, and then the discharge superheat degree is The expansion valve corresponding to the outdoor heat exchanger that is not functioning as a condenser is fully closed when the second discharge superheat degree is less than or equal to a second discharge superheat degree that is smaller than the first discharge superheat degree.
The air conditioner according to claim 1.   The control means, when opening the expansion valve corresponding to the outdoor heat exchanger that is not functioning as a condenser, the opening of the expansion valve is the minimum opening through which the refrigerant flows, The air conditioning apparatus according to claim 1 or 2.

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