JP2017142018A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner in which each indoor unit can sufficiently exert space heating ability even when an outdoor unit is installed at a position higher than the plurality of indoor units.SOLUTION: A CPU 210 determines whether a value obtained by subtracting an average refrigerant excessive cooling degree SCv from a refrigerant excessive cooling degree SC is -1 or more and 1 or less. When the value obtained by subtracting the average refrigerant excessive cooling degree SCv from the refrigerant excessive cooling degree SC is -1 or more and 1 or less, the CPU 210 makes reference to a highest refrigerant excessive cooling degree table stored in a storing section 220 and determines whether there is an indoor unit having the refrigerant excessive cooling degree SC larger than the maximum highest refrigerant excessive cooling degree SCh. When there is an indoor unit having the refrigerant excessive cooling degree SC larger than the maximum highest refrigerant excessive cooling degree SCh, the CPU 210 adds 5 pulse to an outdoor expansion valve 24 and increases opening degree of the outdoor expansion valve 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an air conditioner in which a plurality of indoor units are connected to a refrigerant pipe by at least one outdoor unit.

  Conventionally, in an air conditioner in which a plurality of indoor units are connected to at least one outdoor unit by a liquid pipe and a gas pipe, each indoor unit is installed with a height difference, and the outdoor unit is positioned higher than each indoor unit. It may be installed in. When the air conditioner thus installed performs a heating operation, there is a possibility that sufficient heating capacity may not be obtained with an indoor unit installed at a low position for the reason described below.

  In the heating operation, it is necessary to flow the liquid refrigerant condensed in the indoor heat exchanger of each indoor unit and flowing out into the liquid pipe toward the outdoor unit installed at a position higher than each indoor unit against the gravity. For this reason, the pressure of the liquid refrigerant on the downstream side (outdoor unit side) of the indoor expansion valve of the indoor unit installed at the low position is the pressure of the liquid refrigerant on the downstream side of the indoor expansion valve of the indoor unit installed at the high position. Higher than.

  Therefore, the indoor expansion valve of the indoor unit installed at a position where the pressure difference between the refrigerant pressure on the upstream side (indoor heat exchanger side) and the refrigerant pressure on the downstream side of the indoor expansion valve of the indoor unit installed at a low position is high. The pressure difference between the refrigerant pressure on the upstream side and the refrigerant pressure on the downstream side becomes smaller. The smaller the pressure difference between the refrigerant pressure upstream of the indoor expansion valve and the refrigerant pressure downstream, the smaller the amount of refrigerant flowing through the indoor expansion valve. Therefore, more refrigerant flows to the indoor unit installed at a higher position, but lower. There is a possibility that the amount of refrigerant flowing to the indoor unit installed at the position decreases, and the indoor unit cannot obtain sufficient heating capacity.

  The multi-type air conditioner described in Patent Document 1 is an indoor unit in which the degree of refrigerant supercooling does not reach the target value after a predetermined time has elapsed since the start of heating operation when a plurality of indoor units are installed with a height difference. If there is, it is determined that the heating capacity of the indoor unit cannot be demonstrated. Then, the target refrigerant subcooling degree of the indoor unit having the smallest refrigerant subcooling degree is increased by a predetermined value, while the target refrigerant subcooling degree of the indoor unit having the largest refrigerant subcooling degree is lowered by a predetermined value, thereby heating the indoor unit. Non-heating cancellation control is performed so that the heating capacity can be sufficiently exerted in indoor units that are not capable of exhibiting the capacity.

  In addition, when there is an indoor unit in which the heating capacity cannot be exhibited during the heating operation of the air conditioner, the present applicant uses the maximum value and the minimum value of the refrigerant supercooling degree in each indoor unit as an average. This is a kind of non-heating cancellation control that calculates the degree of refrigerant supercooling and adjusts the opening of the indoor expansion valve of each indoor unit so that the refrigerant supercooling degree of each indoor unit is the average refrigerant supercooling degree obtained. The air conditioning apparatus which performs refrigerant | coolant amount balance control has been proposed previously (Japanese Patent Application No. 2006-2698).

JP 2011-158118 A

  By the way, at the time of designing each indoor unit, the size of the indoor heat exchanger, the air volume of the indoor fan, and the like are determined so that a predetermined heating capacity can be exhibited. When the maximum heating capacity is requested in each indoor unit, the maximum refrigerant subcooling degree on the refrigerant outlet side of the indoor heat exchanger corresponding to the maximum heating capacity (hereinafter referred to as the maximum refrigerant subcooling degree) Exists. In other words, when heating operation is performed in each indoor unit, if the refrigerant subcooling degree on the refrigerant outlet side of the indoor heat exchanger is equal to or less than the maximum refrigerant subcooling degree, the maximum heating capacity is required in each indoor unit. But this heating ability can be demonstrated.

  When the above-described non-heating cancellation control is performed, the refrigerant flow rate decreases in the indoor unit in which the opening degree of the indoor expansion valve is reduced, while the refrigerant flow rate increases in the indoor unit in which the opening degree of the indoor expansion valve is increased. When such control is performed periodically (for example, every 30 seconds), the refrigerant circulation amount on the indoor unit side as seen from the outdoor unit is stabilized in an increased state as compared to before the unheated cancellation control is performed. For this reason, the refrigerant supercooling degree in each indoor unit becomes stable at a value smaller than the refrigerant supercooling degree at the time when the control is started.

  For example, when heating operation is performed with an air conditioner in which three indoor units are installed with a height difference, the indoor unit installed at the highest position has a refrigerant supercooling degree of 6 deg and is installed at the lowest position. It is assumed that the refrigerant subcooling degree of the indoor unit is 26 deg, and the refrigerant subcooling degree of the indoor unit installed at a height between these is 10 deg. In this case, in the indoor unit installed at the lowest position, the degree of refrigerant supercooling is larger than that of other indoor units, but this is on the refrigerant outlet side of the indoor heat exchanger of the indoor unit. This is because the liquid refrigerant temperature has become a low temperature that is compatible with the room temperature, and this indicates that the liquid refrigerant has accumulated in the indoor heat exchanger and the indoor unit cannot exert its heating capacity.

  When the refrigerant amount balance control proposed by the present applicant is executed in the air conditioner that performs the heating operation in the state as described above, the liquid refrigerant staying in the indoor unit installed at the lowest position Escape from the machine. Then, by continuously performing the refrigerant amount balance control, the refrigerant flows through the indoor unit installed at the lowest position, and the refrigerant circulation amount on the indoor unit side as viewed from the outdoor unit increases and is the lowest. The refrigerant subcooling degree in the indoor unit installed at the position is lower than 26 deg which is a value before the refrigerant amount balance control is performed. As a result, the indoor unit installed at the lowest position can exhibit the heating capacity, and the average refrigerant subcooling degree is lower than 16 deg which is the average refrigerant subcooling degree before the refrigerant amount balance control is performed. For example, it becomes 10 deg, and the refrigerant subcooling degree in each indoor unit is stabilized at a value near the average refrigerant subcooling degree (for example, ± 1 deg).

  When the refrigerant amount balance control is performed in this way and settles to a value in the vicinity of the average supercooling degree in each indoor unit, the indoor unit in which the maximum refrigerant supercooling degree is smaller than the refrigerant supercooling degree, for example, the maximum refrigerant overcooling degree. When there is an 8 deg indoor unit whose degree of cooling is less than 10 deg which is the current refrigerant supercooling level, there is a possibility that the indoor unit has not been able to exhibit sufficient heating capacity.

  The present invention solves the above-described problems, and even when the outdoor unit is installed at a position higher than a plurality of indoor units, the air that can sufficiently exhibit the heating capacity in each indoor unit during heating operation It aims at providing a harmony device.

  In order to solve the above problems, an air conditioner of the present invention includes an outdoor unit having a compressor and a discharge pressure detecting means for detecting a discharge pressure that is a pressure of a refrigerant discharged from the compressor, and an indoor heat exchanger. And a plurality of indoor units having liquid side temperature detecting means for detecting a heat exchange outlet temperature which is a temperature of a refrigerant flowing out of the indoor heat exchanger when the indoor expansion valve and the indoor heat exchanger function as a condenser The outdoor unit is installed above a plurality of indoor units and there is a difference in height in the installation location of the plurality of indoor units, and heating is performed when the air conditioner is performing a heating operation. When there is an indoor unit that is not capable of exhibiting capability, the indoor unit has a control unit that executes non-heating cancellation control so that the indoor unit can exhibit heating capability. This control means stores the maximum refrigerant subcooling degree, which is an individual value for a plurality of indoor units and is the maximum value of the refrigerant subcooling degree that can exhibit a predetermined heating capacity in the plurality of indoor units. The difference between the average refrigerant subcooling degree calculated by executing the non-heating cancellation control and using the refrigerant subcooling degree of each indoor unit and the refrigerant subcooling degree of each indoor unit is a value within a predetermined range. When there is an indoor unit having a refrigerant supercooling degree larger than the maximum refrigerant supercooling degree, surplus refrigerant recovery control for recovering refrigerant from a plurality of indoor units to the outdoor unit is performed.

  According to the air conditioner of the present invention configured as described above, excess refrigerant recovery control is performed to reduce the amount of refrigerant flowing through each indoor unit so that the refrigerant subcooling degree in each indoor unit is the highest refrigerant subcooling. Since the temperature is not exceeded, the heating capacity can be sufficiently exhibited in each indoor unit.

It is explanatory drawing of the air conditioning apparatus in embodiment of this invention, (A) is a refrigerant circuit figure, (B) is a block diagram of an outdoor unit control means and an indoor unit control means. It is drawing which shows the installation state of an indoor unit and the outdoor unit in the embodiment of the present invention, and the operation state of each indoor unit. It is a maximum refrigerant | coolant supercooling degree table in embodiment of this invention. It is a flowchart explaining the process in the outdoor unit control part 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, three indoor units installed on each floor of a building are connected in parallel to one outdoor unit installed on the roof of a building, and cooling operation or heating operation can be performed simultaneously on all indoor units An air conditioning apparatus will be described as an example. The present invention is not limited to the following embodiments, and can be variously modified without departing from the gist of the present invention.

  As shown in FIG. 1 (A) and FIG. 2, an air conditioner 1 according to this embodiment is installed on the floor of a three-story building and one outdoor unit 2 installed on each floor of the building. The unit 2 includes three indoor units 5 a to 5 c connected in parallel by a liquid pipe 8 and a gas pipe 9. Specifically, the liquid pipe 8 has one end connected to the closing valve 25 of the outdoor unit 2 and the other end branched to be connected to the liquid pipe connecting portions 53a to 53c of the indoor units 5a to 5c. The gas pipe 9 has one end connected to the closing valve 26 of the outdoor unit 2 and the other end branched to be connected to the gas pipe connecting portions 54a to 54c of the indoor units 5a to 5c. The refrigerant circuit 100 of the air conditioner 1 is configured as described above.

  First, the outdoor unit 2 will be described. The outdoor unit 2 includes a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, an outdoor expansion valve 24, a closing valve 25 to which one end of the liquid pipe 8 is connected, and one end of the gas pipe 9. And a close-up valve 26, an accumulator 28 as a refrigerant recovery container, and an outdoor fan 27. These devices other than the outdoor fan 27 are connected to each other through refrigerant pipes described in detail below to constitute an outdoor unit refrigerant circuit 20 that forms part of the refrigerant circuit 100.

  The compressor 21 is a variable capacity compressor that can vary its operating capacity by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. The refrigerant discharge side of the compressor 21 is connected to a port a of a four-way valve 22 described later by a discharge pipe 41, and the refrigerant suction side of the compressor 21 is connected to the refrigerant outflow side of the accumulator 28 by a suction pipe 42. Has been.

  The four-way valve 22 is a valve for switching the direction in which the refrigerant flows, and includes four ports a, b, c, and d. The port a is connected to the refrigerant discharge side of the compressor 21 by the discharge pipe 41 as described above. The port b is connected to one refrigerant inlet / outlet of the outdoor heat exchanger 23 by a refrigerant pipe 43. The port c is connected to the refrigerant inflow side of the accumulator 28 by a refrigerant pipe 46. The port d is connected to the closing valve 26 by an outdoor unit gas pipe 45.

  The outdoor heat exchanger 23 exchanges heat between the refrigerant and outside air taken into the outdoor unit 2 by rotation of an outdoor fan 27 described later. As described above, one refrigerant inlet / outlet of the outdoor heat exchanger 23 is connected to the port b of the four-way valve 22 by the refrigerant pipe 43, and the other refrigerant inlet / outlet is connected to the closing valve 25 by the outdoor unit liquid pipe 44.

  The outdoor expansion valve 24 is provided in the outdoor unit liquid pipe 44. The outdoor expansion valve 24 is an electronic expansion valve, and the amount of refrigerant flowing into the outdoor heat exchanger 23 or the amount of refrigerant flowing out of the outdoor heat exchanger 23 is adjusted by adjusting the opening thereof. The opening degree of the outdoor expansion valve 24 is fully opened when the air conditioner 1 is performing a cooling operation. In addition, when the air conditioner 1 is performing a heating operation, the opening temperature is controlled according to the discharge temperature of the compressor 21 detected by a discharge temperature sensor 33 described later, so that the discharge temperature has a performance upper limit value. I do not exceed it.

  The outdoor fan 27 is formed of a resin material and is disposed in the vicinity of the outdoor heat exchanger 23. The outdoor fan 27 is rotated by a fan motor (not shown) to take outside air from a suction port (not shown) into the outdoor unit 2, and the outdoor air heat exchanged with the refrigerant in the outdoor heat exchanger 23 is sent from the blower outlet (not shown) to the outdoor unit 2. To the outside.

  As described above, the accumulator 28 has the refrigerant inflow side connected to the port c of the four-way valve 22 via the refrigerant pipe 46 and the refrigerant outflow side connected to the refrigerant intake side of the compressor 21 via the suction pipe 42. The accumulator 28 separates the refrigerant flowing into the accumulator 28 from the refrigerant pipe 46 into a gas refrigerant and a liquid refrigerant, and causes the compressor 21 to suck only the gas refrigerant.

  In addition to the configuration described above, the outdoor unit 2 is provided with various sensors. As shown in FIG. 1A, a discharge pressure sensor 31 that is a discharge pressure detecting unit that detects a discharge pressure that is a pressure of a refrigerant discharged from the compressor 21 and a discharge pressure sensor 31 that discharges from the compressor 21 A discharge temperature sensor 33 for detecting the temperature of the refrigerant to be discharged is provided. Near the refrigerant inlet of the accumulator 28 in the refrigerant pipe 46, a suction pressure sensor 32 that detects the pressure of the refrigerant sucked into the compressor 21 and a suction temperature sensor 34 that detects the temperature of the refrigerant sucked into the compressor 21. And are provided.

  Between the outdoor heat exchanger 23 and the outdoor expansion valve 24 in the outdoor unit liquid pipe 44, the temperature of the refrigerant flowing into the outdoor heat exchanger 23 or the temperature of the refrigerant flowing out of the outdoor heat exchanger 23 is detected. A heat exchanger temperature sensor 35 is provided. An outdoor air temperature sensor 36 that detects the temperature of the outside air that flows into the outdoor unit 2, that is, the outside air temperature, is provided near the suction port (not shown) of the outdoor unit 2.

  The outdoor unit 2 includes an outdoor unit control means 200. The outdoor unit control means 200 is mounted on a control board stored in an electrical component box (not shown) of the outdoor unit 2. As shown in FIG. 1B, the outdoor unit control means 200 includes a CPU 210, a storage unit 220, a communication unit 230, and a sensor input unit 240.

  The storage unit 220 includes a ROM and a RAM, and stores a control program for the outdoor unit 2, detection values corresponding to detection signals from various sensors, control states of the compressor 21 and the outdoor fan 27, and the like. The communication unit 230 is an interface that performs communication with the indoor units 5a to 5c. The sensor input unit 240 captures detection results from various sensors of the outdoor unit 2 and outputs them to the CPU 210.

  CPU210 takes in the detection result in each sensor of outdoor unit 2 mentioned above via sensor input part 240. FIG. In addition, the CPU 210 takes in control signals transmitted from the indoor units 5 a to 5 c via the communication unit 230. The CPU 210 performs drive control of the compressor 21 and the outdoor fan 27 based on the detection results and control signals taken in. In addition, the CPU 210 performs switching control of the four-way valve 22 based on the detection results and control signals taken in. Furthermore, the CPU 210 adjusts the opening degree of the outdoor expansion valve 24 based on the acquired detection result and control signal.

  Next, the three indoor units 5a to 5c will be described. The three indoor units 5a to 5c are branched into indoor heat exchangers 51a to 51c, indoor expansion valves 52a to 52c, and liquid pipe connection portions 53a to 53c to which the other ends of the branched liquid pipes 8 are connected. Gas pipe connection parts 54a to 54c to which the other end of the gas pipe 9 is connected and indoor fans 55a to 55c are provided. And these each apparatus except indoor fan 55a-55c is mutually connected by each refrigerant | coolant piping explained in full detail below, and comprises the indoor unit refrigerant circuit 50a-50c which makes a part of refrigerant circuit 100. FIG.

  In addition, since the structure of all the indoor units 5a-5c is the same, in the following description, only the structure of the indoor unit 5a is demonstrated and description is abbreviate | omitted about the other indoor units 5b and 5c. Moreover, in FIG. 1, what changed the end of the number provided to the component apparatus of the indoor unit 5a from a to b and c becomes the component apparatus of the indoor units 5b and 5c corresponding to the component apparatus of the outdoor unit 5a. .

The indoor heat exchanger 51a exchanges heat between indoor air taken into the indoor unit 5a from a suction port (not shown) by rotation of a refrigerant and an indoor fan 55a described later, and one refrigerant inlet / outlet is a liquid pipe connection portion. 53a is connected by an indoor unit liquid pipe 71a, and the other refrigerant inlet / outlet is connected to the gas pipe connecting part 54a by an indoor unit gas pipe 72a. The indoor heat exchanger 51a functions as an evaporator when the indoor unit 5a performs a cooling operation, and functions as a condenser when the indoor unit 5a performs a heating operation.
Note that the refrigerant pipes of the liquid pipe connecting part 53a and the gas pipe connecting part 54a are connected by welding, flare nuts, or the like.

  The indoor expansion valve 52a is provided in the indoor unit liquid pipe 71a. The indoor expansion valve 52a is an electronic expansion valve, and when the indoor heat exchanger 51a functions as an evaporator, that is, when the indoor unit 5a performs a cooling operation, the opening degree of the indoor expansion valve 52a depends on the refrigerant outlet (gas gas) of the indoor heat exchanger 51a. The refrigerant superheat degree at the pipe connecting portion 54a side) is adjusted to be the target refrigerant superheat degree. Here, the target refrigerant superheat degree is a refrigerant superheat degree for exhibiting sufficient cooling capacity in the indoor unit 5a. Further, when the indoor heat exchanger 51a functions as a condenser, that is, when the indoor unit 5a performs a heating operation, the opening of the indoor expansion valve 52a is the refrigerant outlet (liquid pipe connection portion) of the indoor heat exchanger 51a. 53a side) is adjusted so that the refrigerant subcooling degree on the refrigerant side becomes an average refrigerant subcooling degree described later.

  The indoor fan 55a is formed of a resin material and is disposed in the vicinity of the indoor heat exchanger 51a. The indoor fan 55a is rotated by a fan motor (not shown) to take indoor air from the suction port (not shown) into the indoor unit 5a, and the indoor air exchanged with the refrigerant in the indoor heat exchanger 51a from the blower outlet (not shown). Supply indoors.

  In addition to the configuration described above, the indoor unit 5a is provided with various sensors. Between the indoor heat exchanger 51a and the indoor expansion valve 52a in the indoor unit liquid pipe 71a, liquid side temperature detecting means for detecting the temperature of the refrigerant flowing into or out of the indoor heat exchanger 51a. A certain liquid side temperature sensor 61a is provided. The indoor unit gas pipe 72a is provided with a gas side temperature sensor 62a that detects the temperature of the refrigerant flowing out of the indoor heat exchanger 51a or flowing into the indoor heat exchanger 51a. A suction temperature sensor 63a for detecting the temperature of the indoor air flowing into the indoor unit 5a, that is, the suction temperature, is provided near the suction port (not shown) of the indoor unit 5a. A blowout temperature sensor 64a for detecting the temperature of the air discharged from the indoor unit 5a into the room, that is, the blowout temperature, is exchanged with the refrigerant in the indoor heat exchanger 51a near the blowout port (not shown) of the indoor unit 5a. Is provided.

  The indoor unit 5a includes an indoor unit control means 500a. The indoor unit control means 500a is mounted on a control board stored in an electrical component box (not shown) of the indoor unit 5a. As shown in FIG. 1B, a CPU 510a, a storage unit 520a, a communication unit 530a, And a sensor input unit 540a.

  The storage unit 520a includes a ROM and a RAM, and stores a control program for the indoor unit 5a, detection values corresponding to detection signals from various sensors, setting information regarding air conditioning operation by the user, and the like. The communication unit 530a is an interface that communicates with the outdoor unit 2 and the other indoor units 5b and 5c. The sensor input unit 540a captures detection results from various sensors of the indoor unit 5a and outputs them to the CPU 510a.

The CPU 510a takes in the detection result of each sensor of the indoor unit 5a described above via the sensor input unit 540a. Further, the CPU 510a takes in a signal including operation information set by operating a remote controller (not shown), a timer operation setting, and the like via a remote control light receiving unit (not shown). Further, the CPU 510a transmits a control signal including an operation start / stop signal and operation information (set temperature, indoor temperature, etc.) to the outdoor unit 2 via the communication unit 530a, and discharge pressure detected by the outdoor unit 2. A control signal including such information is received from the outdoor unit 2 via the communication unit 530a. The CPU 510a performs the opening degree adjustment of the indoor expansion valve 52a and the drive control of the indoor fan 55a based on the acquired detection result and the signal transmitted from the remote controller and the outdoor unit 2.
The outdoor unit control unit 200 and the indoor unit control units 500a to 500c described above constitute the control unit of the present invention.

  The air conditioning apparatus 1 described above is installed in a building 600 shown in FIG. Specifically, the outdoor unit 2 is arranged on the roof (RF), the indoor unit 5a is installed on the third floor, the indoor unit 5b is installed on the second floor, and the indoor unit 5c is installed on the first floor. And the outdoor unit 2 and the indoor units 5a-5c are mutually connected by the liquid pipe 8 and the gas pipe 9 which were mentioned above, and these liquid pipe 8 and the gas pipe 9 are in the wall surface of the building 600 which is not shown in figure. Or buried in the ceiling. In FIG. 2, the height difference between the indoor unit 5a installed on the top floor (3rd floor) and the indoor unit 5c installed on the bottom floor (1st floor) is represented by H.

  Next, the flow of the refrigerant and the operation of each part in the refrigerant circuit 100 during the air conditioning operation of the air-conditioning apparatus 1 in the present embodiment will be described with reference to FIG. In the following description, the case where the indoor units 5a to 5c perform the heating operation will be described, and the detailed description will be omitted when the cooling / defrosting operation is performed. Moreover, the arrow in FIG. 1 (A) has shown the flow of the refrigerant | coolant at the time of heating operation.

  As shown in FIG. 1A, when the indoor units 5a to 5c perform the heating operation, the CPU 210 of the outdoor unit control means 200 is in a state where the four-way valve 22 is indicated by a solid line, that is, the port a and the port of the four-way valve 22 It switches so that d may communicate and port b and port c communicate. Thereby, the refrigerant circuit 100 becomes a heating cycle in which the outdoor heat exchanger 23 functions as an evaporator and the indoor heat exchangers 51a to 51c function as condensers.

  The high-pressure refrigerant discharged from the compressor 21 flows through the discharge pipe 41 and flows into the four-way valve 22, and from the four-way valve 22 to the outdoor unit gas pipe 45, the closing valve 26, the gas pipe 9, and the gas pipe connection portions 54 a to 54 c. In this order and flow into the indoor units 5a to 5c. The refrigerant that has flowed into the indoor units 5a to 5c flows through the indoor unit gas pipes 72a to 72c, flows into the indoor heat exchangers 51a to 51c, and is taken into the indoor units 5a to 5c by the rotation of the indoor fans 55a to 55c. Heat exchanges with room air and condenses. As described above, the indoor heat exchangers 51a to 51c function as condensers, and the indoor air that has exchanged heat with the refrigerant in the indoor heat exchangers 51a to 51c is blown into the room from a blowout port (not shown), thereby The room where the machines 5a to 5c are installed is heated.

  The refrigerant flowing out of the indoor heat exchangers 51a to 51c flows through the indoor unit liquid pipes 71a to 71c, passes through the indoor expansion valves 52a to 52c, and is decompressed. The decompressed refrigerant flows through the indoor unit liquid pipes 71 a to 71 c and the liquid pipe connection portions 53 a to 53 c and flows into the liquid pipe 8.

  The refrigerant flowing through the liquid pipe 8 flows into the outdoor unit 2 through the closing valve 25. The refrigerant flowing into the outdoor unit 2 flows through the outdoor unit liquid pipe 44 and is further reduced in pressure when passing through the outdoor expansion valve 24 having an opening degree corresponding to the discharge temperature of the compressor 21 detected by the discharge temperature sensor 33. The The refrigerant flowing into the outdoor heat exchanger 23 from the outdoor unit liquid pipe 44 evaporates by exchanging heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 27. The refrigerant flowing out of the outdoor heat exchanger 23 flows in the order of the refrigerant pipe 43, the four-way valve 22, the refrigerant pipe 46, the accumulator 28, and the suction pipe 42, and is sucked into the compressor 21 and compressed again.

  When the indoor units 5a to 5c perform the cooling / defrosting operation, the CPU 210 indicates that the four-way valve 22 is indicated by a broken line, that is, the port a and the port b of the four-way valve 22 communicate with each other. And so that port d communicates. Thereby, the refrigerant circuit 100 becomes a cooling cycle in which the outdoor heat exchanger 23 functions as a condenser and the indoor heat exchangers 51a to 51c function as evaporators.

  Next, the operation | movement of the refrigerant circuit in connection with this invention in the air conditioning apparatus 1, the effect | action, and an effect are demonstrated using FIG. 1 thru | or FIG.

  As described above with reference to FIG. 2, in the air conditioner 1 of the present embodiment, the outdoor unit 2 is installed on the roof of the building 600, and the indoor units 5a to 5c are installed on each floor. That is, the outdoor unit 2 is installed at a position higher than the indoor units 5a to 5c, and the installation location of the indoor unit 5a and the indoor unit 5c has a height difference H. In this case, when the air conditioning apparatus 1 performs a heating operation, there are the following problems.

  In the heating operation, the gas refrigerant discharged from the compressor 21 flows through the outdoor unit gas pipe 45 from the discharge pipe 41 through the four-way valve 22, flows out of the outdoor unit 2, and the indoor heat exchangers of the indoor units 5a to 5c. It flows into 51a-51c and condenses. At this time, since the outdoor unit 2 is installed at a position higher than the indoor units 5a to 5c, the liquid refrigerant condensed in the indoor heat exchangers 51a to 51c and flowing out to the liquid pipe 8 is against the gravity against the outdoor unit 2 Will flow through the liquid pipe 8.

  Therefore, the pressure of the liquid refrigerant on the downstream side (outdoor unit 2 side) of the indoor expansion valve 52c of the indoor unit 5c installed on the first floor is the indoor expansion valve of the indoor units 5a and 5b installed on the other floors. The pressure difference between the refrigerant pressure on the upstream side (the indoor heat exchanger 51c side) of the indoor expansion valve 52c of the indoor unit 5c and the refrigerant pressure on the downstream side is higher than the pressure of the liquid refrigerant on the downstream side of 52a and 52b. It becomes smaller than the pressure difference between the refrigerant pressure upstream of the indoor expansion valves 52a and 52b and the refrigerant pressure downstream of the machines 5a and 5b.

  In the state of the refrigerant circuit 100 as described above, the smaller the pressure difference between the refrigerant pressure upstream of the indoor expansion valves 52a to 52c and the refrigerant pressure downstream, the smaller the amount of refrigerant flowing through the indoor expansion valves 52a to 52c. Accordingly, the amount of refrigerant flowing through the indoor unit 5c installed on the first floor is smaller than the amount of refrigerant flowing through the other indoor units 5a and 5b. This becomes more significant as the height difference H between the indoor unit 5c installed on the first floor (lowest position) and the indoor unit 5a installed on the third floor (highest position) increases. Is increased (for example, 50 m), the liquid refrigerant flowing out from the indoor unit 5 c to the liquid pipe 8 may not flow toward the outdoor unit 2, and the liquid refrigerant may stay below the liquid pipe 8. If the liquid refrigerant stays below the liquid pipe 8, even if the indoor expansion valve 5c is fully opened, the refrigerant does not flow into the indoor unit 5c, and the indoor unit 5c may not be able to exhibit the heating capability.

  The state where the heating capability is not exhibited in the indoor unit 5c described above will be described using the example shown in FIG. In the following description, the high-pressure saturation temperature calculated using the discharge pressure detected by the discharge pressure sensor 31 corresponding to the condensation temperature of the indoor heat exchangers 51a to 51c is Ths, and the indoor heat exchangers 51a of the indoor units 5a to 5c. ˜51c is the temperature of the refrigerant flowing out and is detected by the liquid side temperature sensors 61a to 61c. The heat exchange outlet temperature is To (if it is necessary to individually refer to the indoor units 5a to 5c, it is described as Toa to Toc) The refrigerant subcooling degree on the refrigerant outlet side of the indoor heat exchangers 51a to 51c of the indoor units 5a to 5c is SC (when it is necessary to individually refer to the indoor units 5a to 5c, it is described as SCa to SCc). And

  In addition, the maximum refrigerant supercooling degree in the indoor units 5a to 5c is SCh (indicated as SCha to SChc when it is necessary to individually refer to the indoor units 5a to 5c). This maximum refrigerant supercooling degree SCh is the refrigerant of the indoor heat exchangers 51a to 51c formed so that the indoor units 5a to 5c can exhibit a predetermined maximum heating capacity when the indoor units 5a to 5c are designed. It is the maximum value of the degree of refrigerant supercooling on the outlet side. In other words, if the refrigerant supercooling degree SC of the indoor units 5a to 5c described above is a value equal to or lower than the maximum refrigerant supercooling degree SCh, the indoor units 5a to 5c can exhibit this heating ability even if the maximum heating capacity is required. .

  The maximum refrigerant subcooling degree SCh of the indoor units 5a to 5c is stored in advance in the storage unit 220 of the outdoor unit control means 200 as the maximum refrigerant subcooling degree table 300 shown in FIG. In the maximum refrigerant supercooling degree table 300, the maximum refrigerant supercooling degree SCh is determined for each of the indoor units 5a to 5c. In this embodiment, the maximum refrigerant subcooling degree SCha of the indoor unit 5a is 8 deg, and the indoor unit 5b. The maximum refrigerant supercooling degree SChb is 10 deg, and the maximum refrigerant subcooling degree SChc of the indoor unit 5c is 12 deg.

  In the example shown in FIG. 2, the outside air temperature detected by the outside air temperature sensor 36 during heating operation is 0 ° C., and the heating set temperature in the indoor units 5 a to 5 c is 24 ° C. Furthermore, the refrigerant supercooling degree used when determining whether or not there is an indoor unit in which liquid refrigerant is retained in the indoor heat exchanger is set as the liquid refrigerant retaining supercooling degree SCp. The degree of supercooling SCp when the liquid refrigerant is retained is determined in advance by performing a test or the like, and is, for example, 20 deg in the present embodiment.

  When the air-conditioning apparatus 1 is performing the heating operation under the conditions described above, the state of the indoor units 5a to 5c is the state “before refrigerant amount balance control” in FIG. First, in the indoor unit 5a, the heat exchange outlet temperature Toa is 42 ° C., and the refrigerant supercooling degree SCa is high pressure saturation temperature Ths−heat exchange outlet temperature Toa = 48−42 = 6 deg. That is, since the refrigerant subcooling degree SCa = 6 deg <the subcooling degree SCp = 20 deg when the liquid refrigerant is retained, it is determined that the liquid refrigerant does not stay in the indoor unit 5a and the heating capacity is sufficiently exhibited.

  Next, in the indoor unit 5b, the heat exchange outlet temperature Tob is 40 ° C., and the refrigerant supercooling degree SCb is high-pressure saturation temperature Ths−heat exchange outlet temperature Tob = 48−40 = 8 deg. That is, since the refrigerant subcooling degree SCb = 8 deg <the liquid refrigerant stagnation subcooling degree SCp = 20 deg, it is determined that the liquid refrigerant does not stay in the indoor unit 5b and the heating capacity can be sufficiently exhibited.

  In the indoor unit 5c, the heat exchange outlet temperature Toc is 22 ° C., and the refrigerant supercooling degree SCc is high-pressure saturation temperature Ths−heat exchange outlet temperature Toc = 48−22 = 26 deg. That is, since the refrigerant subcooling degree SCc = 26 deg> the liquid refrigerant staying supercooling degree SCp = 20 deg, it is determined that the heating capacity cannot be exhibited in the indoor unit 5c because the liquid refrigerant stays there.

  As described above, when the air-conditioning apparatus 1 is in the heating operation, if the liquid refrigerant is retained in the indoor unit 5c and the heating capacity is not exerted, the liquid refrigerant remaining in the indoor unit 5c is removed from the indoor unit 5c. The refrigerant amount balance control (corresponding to the non-heating cancellation control of the present invention) is executed so that the heating capacity can be sufficiently exerted in the indoor unit 5c. Specifically, among the refrigerant supercooling degrees SC of the indoor units 5a to 5c, the maximum value (in FIG. 2, the refrigerant supercooling degree of the indoor unit 5c: 26 deg) and the minimum value (in FIG. 2, the refrigerant supercooling degree of the indoor unit 5a). Average refrigerant supercooling degree (hereinafter referred to as average refrigerant supercooling degree SCv) = (26 + 6) / 2 = 18 deg, which is an average value of the degree of cooling: 6 deg). And the opening degree of indoor expansion valve 52a-52c of indoor unit 5a-5c is adjusted so that it may become the average refrigerant | coolant subcooling degree SCv which the refrigerant | coolant subcooling degree SCa-SCc of indoor unit 5a-5c calculated | required.

  When the refrigerant amount balance control is performed, in the indoor units 5a and 5b having a refrigerant subcooling degree smaller than the average refrigerant subcooling degree SCv, an indoor expansion valve is used to increase the refrigerant subcooling degrees SCa and SCb to the average refrigerant subcooling degree SCv. Since the opening degree of 52a, 52b is restrict | squeezed, the refrigerant | coolant pressure of the downstream of indoor expansion valve 52a, 52b falls.

  At this time, in the indoor unit 5c having a refrigerant subcooling degree larger than the average refrigerant subcooling degree SCv, the refrigerant pressure on the downstream side of the indoor expansion valve 52c is also reduced by the refrigerant pressure on the downstream side of the indoor expansion valves 52a and 52b being lowered. Therefore, the pressure difference between the upstream side and the downstream side of the indoor expansion valve 52c increases. Thereby, when the opening degree of the indoor expansion valve 52c is increased in order to reduce the refrigerant subcooling degree of the indoor unit 5c to the average refrigerant subcooling degree SCv in the refrigerant amount balance control, the opening degree is fully opened. Even in this case, the liquid refrigerant staying in the indoor heat exchanger 51c of the indoor unit 5c flows out to the liquid pipe 8.

  When the refrigerant amount balance control described above is continuously performed, the refrigerant flows into the indoor unit 5c, and the liquid refrigerant that has accumulated in the indoor heat exchanger 51c of the indoor unit 5c flows out into the refrigerant circuit 100, and the outdoor unit The refrigerant circulation amount in the refrigerant circuit 100 on the indoor units 5a to 5c side as viewed from the unit 2 is increased as compared to before the refrigerant amount balance control is performed. Further, the refrigerant supercooling degree SCc in the indoor unit 5c is lower than 26 deg which is a value before the refrigerant amount balance control is performed. As a result, the average refrigerant supercooling degree SCv is lower than 16 deg, which is the value before the refrigerant amount balance control, for example, 10 deg. As shown in the state of “after refrigerant amount balance control” in FIG. In the indoor units 5a to 5c, the heat exchange outlet temperatures Toa to Toc are 38 ° C., and the refrigerant subcooling degrees SCa to SCc are all 10 degrees that is the same as the average refrigerant subcooling degree SCv, and are stabilized at this value. Here, the fact that the refrigerant subcooling degrees SCa to SCc are stabilized does not mean that all the refrigerant subcooling degrees SCa to SCc have the same average refrigerant subcooling degree SCv. When the difference between the SCc and the average refrigerant supercooling degree SCv is in the range of −1 deg to 1 deg, the refrigerant supercooling degrees SCa to SCc may be stable.

  However, when the refrigerant amount balance control is performed during the heating operation and the refrigerant subcooling degrees SCa to SCc are stabilized at a value near the average refrigerant subcooling degree SCv, the refrigerant subcooling degrees SCa to SCc are higher than the maximum refrigerant subcooling degree SCh. If it is a value, the heating capacity is not exhibited in the indoor unit. For example, as shown in FIG. 2, in the indoor unit 5b, the refrigerant subcooling degree SCb and the maximum refrigerant subcooling degree SChb have the same value, and in the indoor unit 5c, the refrigerant subcooling degree SCc is higher than the maximum refrigerant subcooling degree SChc. It is a small value. In these indoor units 5b and 5c, it is considered that the heating capability is sufficiently exhibited. On the other hand, in the indoor unit 5a, the refrigerant subcooling degree SCa is smaller than the maximum refrigerant subcooling degree SChc, and there is a possibility that the indoor unit 5a cannot fully exhibit the heating capacity.

  The reason why the indoor unit having the refrigerant subcooling degree SC smaller than the maximum refrigerant subcooling degree SCh is generated is a large value when the refrigerant subcooling degrees SCa to SCc are stabilized by performing the refrigerant amount balance control (FIG. 2). In the present embodiment described in FIG. This is because when the refrigerant amount balance control is performed, the refrigerant supercooling degrees SCa and SCb are smaller than the average refrigerant subcooling degree SCv in the indoor units 5a and 5b, and the refrigerant subcooling degrees SCa and SCb are increased to the average refrigerant subcooling degree SCv. This is because the opening degree of the indoor expansion valves 52a and 52b is reduced.

  When the indoor expansion valves 52a and 52b are throttled down in the indoor units 5a and 5b, the refrigerant stays in the indoor heat exchangers 51a and 51b. In other words, if the refrigerant amount balance control is continuously performed, the liquid refrigerant staying in the indoor unit 5c flows out from the indoor unit 5c to the refrigerant circuit 100, while the indoor units 5a and 5b are connected to the indoor heat exchangers 51a and 51b. Refrigerant stagnates. As a result, the refrigerant amount in the refrigerant circuit 100 on the indoor units 5a to 5c side viewed from the outdoor unit 2 may be excessive, and as a result, the refrigerant supercooling degrees SCa to SCc are stabilized at high values.

  Therefore, in the present invention, the air conditioner 1 performs refrigerant amount balance control during the heating operation, and at this time, the indoor units 5a to 5c in which the refrigerant subcooling degree SC is stable at a value larger than the maximum refrigerant subcooling degree SCh. Is present, excess refrigerant recovery control for recovering refrigerant in the outdoor unit 2 is performed. Specifically, if the indoor unit 5a to 5c has a value larger than the maximum refrigerant subcooling degree SCh when the refrigerant amount balance control is performed and the refrigerant subcooling degree SC is stabilized, the outdoor expansion valve 24 is opened. The degree is increased at a predetermined rate, and a part of the refrigerant circulating in the refrigerant circuit 100 is stored in the accumulator 21. Here, increasing at a predetermined rate corresponds to, for example, adding a predetermined number of pulses (for example, 5 pulses) to the outdoor expansion valve 24 at an interval (every 30 seconds described above) for performing refrigerant amount balance control. The amount of opening is increased.

  By performing the excess refrigerant recovery control, the refrigerant amount in the refrigerant circuit 100 on the indoor units 5a to 5c side viewed from the outdoor unit 2 is reduced, and the refrigerant supercooling degree SC is reduced. Then, if the surplus refrigerant recovery control is continued until the refrigerant subcooling degree SC becomes a value smaller than the maximum refrigerant subcooling degree SCh of any indoor unit 5a to 5c, the indoor unit 5a can also exert the heating capacity, All of the indoor units 5a to 5c can sufficiently exhibit the heating capacity.

  Next, control at the time of heating operation in the air-conditioning apparatus 1 of the present embodiment will be described with reference to FIG. FIG. 4 shows a flow of processing related to control performed by the CPU 210 of the outdoor unit control unit 200 when the air-conditioning apparatus 1 performs the heating operation. In FIG. 4, 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 processing, for example, control of the refrigerant circuit 100 corresponding to the operating conditions such as the set temperature and the air volume instructed by the user is performed. Description of general processing related to the harmony device 1 is omitted. Moreover, in the following description, the case where all the indoor units 5a to 5c are performing the heating operation will be described as an example.

  In the following description, in addition to the high-pressure saturation temperature Ths, the heat exchange outlet temperature To, the refrigerant subcooling degree SC, the maximum refrigerant subcooling degree SCh, and the average refrigerant subcooling degree SCv, the discharge pressure sensor 31 is used. Let Ph be the discharge pressure that is the refrigerant pressure to be detected.

First, CPU 210 determines whether or not the user's operation instruction is a heating operation instruction (ST1).
If it is not a heating operation instruction (ST1-No), the CPU 210 executes a cooling / dehumidifying operation start process that is a start process of a cooling operation or a dehumidifying operation (ST15). Here, the cooling / dehumidifying operation start process is a process performed when the CPU 210 operates the four-way valve 22 to set the refrigerant circuit 100 to the cooling cycle, and when the cooling operation or the dehumidifying operation is first performed. Then, the CPU 210 activates the compressor 21 and the outdoor fan 27 at a predetermined rotational speed, and controls the driving of the indoor fans 55a to 55c and the indoor expansion valves 52a to 52c with respect to the indoor units 5a to 5c via the communication unit 230. Is instructed to adjust the opening degree of the air and starts control of the cooling operation or the dehumidifying operation (ST16), and the process proceeds to ST12.

  If it is a heating operation instruction in ST1 (ST1-Yes), the CPU 210 executes a heating operation start process (ST2). Here, the heating operation start process is a state in which the CPU 210 operates the four-way valve 22 to bring the refrigerant circuit 100 into the state shown in FIG. 1A, that is, the refrigerant circuit 100 is set to the heating cycle. It is a process performed when performing.

  Next, the CPU 210 starts the heating operation control (ST3). At the start of heating operation control, the CPU 210 activates the compressor 21 and the outdoor fan 27 at a rotational speed corresponding to the required capacity from the indoor units 5a to 5c. The CPU 210 takes in the discharge temperature of the compressor 21 detected by the discharge temperature sensor 33 via the sensor input unit 240 and adjusts the opening degree of the outdoor expansion valve 24 according to the taken-in discharge temperature. Furthermore, CPU210 transmits the driving | operation start signal to the effect of starting heating operation via the communication part 230 with respect to indoor unit 5a-5c.

  The CPUs 510a to 510c of the indoor unit control means 500a to 500c of the indoor units 5a to 5c that have received the operation start signals via the communication units 530a to 530c turn the indoor fans 55a to 55c at the number of rotations according to the air volume instruction of the user. The interior of the indoor heat exchangers 51a to 51c is started so that the refrigerant supercooling degree at the refrigerant outlets (liquid pipe connection parts 53a to 53c side) becomes the target refrigerant subcooling degree (for example, 6 deg) at the start of operation. The opening degree of the expansion valves 52a to 52c is adjusted. Here, the target refrigerant subcooling degree is a value obtained by performing a test or the like in advance and stored in the storage units 530a to 530c, and it has been confirmed that the heating capacity is sufficiently exhibited in each indoor unit. Value. Note that the CPUs 510a to 510c are configured so that the above-described target refrigerant subcooling degree at the start of the operation becomes the above-described target refrigerant subcooling degree until the state of the refrigerant circuit 100 is stabilized after the start of the heating operation (for example, for 3 minutes from the start of operation). The opening degree of the expansion valves 52a to 52c is adjusted.

  Next, the CPU 210 takes in the discharge pressure Ph detected by the discharge pressure sensor 31 via the sensor input unit 240, and sends the heat exchange outlet temperature To (Toa to Toc) from each of the indoor units 5 a to 5 c via the communication unit 230. (ST4). As for the heat exchange outlet temperature To, the CPU 510a to 510c captures the detected values of the liquid side temperature sensors 61a to 61c and the suction temperature sensors 63a to 63c in the indoor units 5a to 5c via the sensor input units 540a to 540c. It is transmitting to the outdoor unit 2 via the units 530a to 530c. Each detection value described above is captured by each CPU and stored in each storage unit at predetermined time intervals (for example, every 30 seconds).

  Next, the CPU 210 obtains the high-pressure saturation temperature Ths using the discharge pressure Ph taken in in ST4 (ST5), and uses the obtained high-pressure saturation temperature Ths and the heat exchange outlet temperature To taken in in ST4, the indoor units 5a to 5a. A refrigerant supercooling degree SC (SCa to SCc) of 5c is obtained (ST6).

    Next, CPU210 calculates average refrigerant | coolant subcooling degree SCv using refrigerant | coolant supercooling degree SC of indoor unit 5a-5c calculated | required by ST6 (ST7). Specifically, the CPU 210 extracts the maximum value and the minimum value from the refrigerant supercooling degrees SCa to SCc of the indoor units 5a to 5c, obtains the average value thereof, and sets this as the average refrigerant subcooling degree SCv. .

Next, the CPU 210 transmits the average refrigerant supercooling degree SCv obtained in ST7 and the high-pressure saturation temperature Ths obtained in ST5 to the indoor units 5a to 5c via the communication unit 230 (ST8). The CPUs 510a to 510c of the indoor units 5a to 5c that have received the average refrigerant supercooling degree SCv and the high pressure saturation temperature Ths via the communication units 530a to 530c, respectively, use the liquid side temperature sensors 61a to 61 from the high pressure saturation temperature Ths received from the outdoor unit 2. The heat exchanger outlet temperatures Toa to Toc detected in 61c are subtracted to obtain the refrigerant subcooling degrees SCa to SCc, and the obtained refrigerant subcooling degrees SCa to SCc become the average refrigerant subcooling degree SCv received from the outdoor unit 2. Next, the opening degree of the indoor expansion valves 52a to 52c is adjusted.
The processes from ST4 to ST8 described above are processes related to the refrigerant amount balance control which is the non-heating cancellation control of the present invention.

  Next, CPU 210 determines whether or not the value obtained by subtracting the average refrigerant subcooling degree SCv obtained in ST7 from the refrigerant subcooling degree SC (SCa to SCc) obtained in ST6 is −1 or more and 1 or less ( ST9). If the value obtained by subtracting the average refrigerant supercooling degree SCv from the refrigerant supercooling degree SC is not -1 or more and 1 or less (ST9-No), the CPU 210 advances the process to ST12.

  If the value obtained by subtracting the average refrigerant supercooling degree SCv from the refrigerant supercooling degree SC is not less than −1 and not more than 1 (ST9—Yes), the CPU 210 determines that the refrigerant supercooling degree SC is stable, and stores it in the storage unit 220. With reference to the stored maximum refrigerant subcooling degree table 300, it is determined whether or not there is an indoor unit having a value larger than the maximum maximum refrigerant subcooling degree SCh among the refrigerant subcooling degrees SC obtained in ST6. (ST10).

If there is no indoor unit having a value larger than the maximum maximum refrigerant supercooling degree SCh among the refrigerant supercooling degrees SC (ST10-No), the CPU 210 proceeds to ST12. If there is an indoor unit having a value larger than the maximum maximum refrigerant supercooling degree SCh among the refrigerant supercooling degrees SC (ST10-Yes), the CPU 210 adds five pulses to the outdoor expansion valve 24 (ST11). The opening degree of 24 is increased and the process proceeds to ST12.
The processes from ST9 to ST11 described above are processes related to surplus refrigerant recovery control of the present invention.

  CPU210 which completed the process of ST11 judges whether there exists the operation mode switching instruction | indication by a user (ST12). Here, the operation mode switching instruction is an instruction to switch from the current operation (here, heating operation) to another operation (cooling operation or dehumidifying operation). When there is an operation mode switching instruction (ST12-Yes), the CPU 210 returns the process to ST1. When there is no operation mode switching instruction (ST12-No), the CPU 210 determines whether or not there is an operation stop instruction by the user (ST13). The operation stop instruction indicates that all the indoor units 5a to 5c stop the operation.

  If there is an operation stop instruction (ST13-Yes), the CPU 210 executes an operation stop process (ST14) and ends the process. In the operation stop process, the CPU 210 stops the compressor 21 and the outdoor fan 27 and fully closes the outdoor expansion valve 24. Moreover, CPU210 transmits the driving | operation stop signal to the effect of stopping a driving | operation via the communication part 230 with respect to indoor unit 5a-5c. The CPUs 510a to 510c of the indoor units 5a to 5c that have received the operation stop signals via the communication units 530a to 530c stop the indoor fans 55a to 55c and fully close the indoor expansion valves 52a to 52c.

  If there is no operation stop instruction in ST13 (ST13-No), CPU 210 determines whether or not the current operation is a heating operation (ST17). If the current operation is the heating operation (ST17-Yes), CPU 210 returns the process to ST3. If the current operation is not the heating operation (ST17-No), that is, if the current operation is the cooling operation or the dehumidifying operation, the CPU 210 returns the process to ST16.

  In the embodiment described above, the case where the refrigerant amount balance control is executed when the heating operation is started has been described as an example. However, after the heating operation is started, the refrigerant supercooling degree SC is the liquid refrigerant retention supercooling degree SCp. The refrigerant amount balance control may be started when there is a larger indoor unit, that is, when it is found that there is an indoor unit that cannot exhibit the heating capacity.

  Further, the case where the accumulator 28 is used as the refrigerant recovery container has been described. However, the present invention is not limited to this, and a refrigerant receiver provided separately from the accumulator 28 may be used as the refrigerant recovery container. When a receiver is provided in the liquid pipe 44, this receiver may be used as a refrigerant recovery container.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Outdoor unit 5a-5c Indoor unit 31 Discharge pressure sensor 51a-51c Indoor heat exchanger 52a-52c Indoor expansion valve 61a-61c Liquid side temperature sensor 100 Refrigerant circuit 200 Outdoor unit control part 210 CPU
300 Maximum refrigerant supercooling degree table 500a to 500c Indoor unit controller 510a to 510c CPU
Ph Discharge pressure SC Refrigerant supercooling degree SCh Maximum refrigerant supercooling degree SCv Average refrigerant supercooling degree Ths High pressure saturation temperature To Heat exchange outlet temperature

Claims (3)

An outdoor unit having a compressor and a discharge pressure detecting means for detecting a discharge pressure that is a pressure of a refrigerant discharged from the compressor;
Liquid side temperature detection for detecting the heat exchange outlet temperature, which is the temperature of the refrigerant flowing out of the indoor heat exchanger when the indoor heat exchanger functions as a condenser. Having a plurality of indoor units having means,
The outdoor unit is installed above the plurality of indoor units, and is an air conditioner having a height difference in the installation location of the plurality of indoor units,
When the air conditioner is performing a heating operation, if there is an indoor unit that does not exhibit the heating capability, non-heating cancellation control is performed so that the indoor unit can exhibit the heating capability. Having control means,
The control means stores a maximum refrigerant subcooling degree which is a maximum value of the refrigerant subcooling degree which is an individual value for the plurality of indoor units and can exhibit a predetermined heating capacity in the plurality of indoor units. The difference between the average refrigerant subcooling degree calculated by executing the unheated elimination control and using the refrigerant subcooling degree of each indoor unit and the refrigerant subcooling degree of each indoor unit is predetermined. Excess refrigerant recovery control for recovering refrigerant from the plurality of indoor units to the outdoor unit if there is an indoor unit whose refrigerant subcooling degree is greater than the maximum refrigerant subcooling degree I do,
An air conditioner characterized by that. The non-heating cancellation control obtains the average refrigerant subcooling degree using the maximum value and the minimum value among the refrigerant subcooling degrees of the plurality of indoor units, and the refrigerant subcooling degree of the plurality of indoor units Adjusting the opening of the indoor expansion valve so as to obtain an average refrigerant supercooling degree,
The air conditioner according to claim 1. The outdoor unit has an outdoor expansion valve and a refrigerant recovery container,
The surplus refrigerant recovery control increases the degree of opening of the outdoor expansion valve by a predetermined ratio and recovers the refrigerant in the refrigerant recovery container.
The air conditioner according to claim 1.

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