JP2021081148A - Air conditioning device - Google Patents

Abstract

To reduce user's discomfort due to excessiveness or shortage of cooling capacity or emission of refrigerant noise while suppressing deterioration in reliability due to stagnation of refrigeration oil.SOLUTION: An air conditioning device includes: outdoor unit control means 200 and indoor unit control means 500 for controlling first oil recovery operation of opening an opening degree of an indoor expansion valve 52 to a first predetermined opening degree and controlling part of respective indoor units 5 to be operated so that the rotation speed of an indoor fans 55 is operated at a low rotation speed and second oil recovery operation of increasing the rotation speed of a compressor 21 to a predetermined rotation speed and opening the opening degree of the indoor expansion valve 52 to a second predetermined opening degree every first predetermined time.SELECTED DRAWING: Figure 1

Description

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

Conventionally, as an air conditioner, a plurality of indoor units are connected to one outdoor unit by a liquid pipe and a gas pipe, and the plurality of indoor units can simultaneously perform cooling operation or heating operation. Are known. Such an air conditioner is provided with an expansion valve corresponding to each indoor unit, and the flow rate of the refrigerant in each indoor unit can be adjusted by adjusting the opening degree of the expansion valve.

When the cooling operation is performed by the air conditioner as described above, the refrigerating machine oil discharged from the compressor together with the refrigerant passes through the outdoor heat exchanger functioning as a condenser and flows into each indoor unit. At this time, since the expansion valve corresponding to the indoor unit that is stopped is fully closed, the refrigerating machine oil that has flowed into the indoor unit is blocked by the fully closed expansion valve, and is upstream from the expansion valve. It stays in the refrigerant pipe (liquid pipe) of the above or in the indoor heat exchanger of the indoor unit that is stopped. The retained refrigerating machine oil cannot flow back to the compressor through the refrigerant circuit unless the expansion valve is opened.

If the refrigerating machine oil stays in the liquid pipe or in the indoor unit that is stopped, the refrigerating machine oil of the compressor becomes insufficient, resulting in poor lubrication, which may reduce the reliability of the air conditioner. Therefore, the refrigerating machine oil is returned to the compressor by periodically opening all the expansion valves, including those corresponding to the indoor unit that is stopped, and performing an oil recovery operation that raises the number of revolutions of the compressor from that during the cooling operation. There is technology (see Patent Document 1).

Japanese Patent No. 6459800

By the way, the storage of refrigerating machine oil is not limited to the inside of the liquid pipe blocked by the fully closed expansion valve and the indoor heat exchanger of the indoor unit that is stopped. Refrigerating machine oil has low viscosity when the temperature is high or when the refrigerant is melted, but otherwise it is highly viscous and it becomes difficult to flow in the refrigerant circuit. Therefore, even if the indoor unit is in operation, the temperature is low and the amount of wet refrigerant (a state in which the gas refrigerant contains a liquid refrigerant) is small, and the downstream side of the indoor heat exchanger or further downstream side thereof. Refrigerant machine oil tends to stay in the refrigerant pipe (gas pipe). Therefore, in the oil recovery operation, not only all expansion valves are opened, including those corresponding to the indoor unit that is stopped, but also a large amount of wet refrigerant flows through the indoor heat exchanger and gas pipe of the indoor unit that is in operation. In addition, it is necessary to open the expansion valve to a sufficient opening.

When such an oil recovery operation is performed, the refrigerant flow rate fluctuates compared to before the oil recovery operation is performed. During the cooling operation before the oil recovery operation, the refrigerant flow rate of each indoor unit is adjusted to the refrigerant flow rate according to the required capacity of each indoor unit by the compressor and the expansion valve corresponding to each indoor unit. The oil recovery operation changes the compressor rotation speed and the opening degree of each expansion valve, and the refrigerant flow rate fluctuates, so that the cooling capacity of the indoor unit during operation becomes insufficient or excessive. In addition, the refrigerant also flows to the stopped indoor unit, and a refrigerant noise is generated. Furthermore, since a large amount of refrigerant is distributed in indoor heat exchangers, gas pipes, etc., the amount of refrigerant distributed on the expansion valve inlet side is reduced, gas-liquid two-phase refrigerant flows into the expansion valve, and the refrigerant noise tends to be loud. .. In particular, when the amount of refrigerant charged is small due to the saving of refrigerant, the refrigerant on the inlet side of the expansion valve tends to have two phases of gas and liquid, so that the above situation is likely to occur.

The disclosed technology was made in view of this point, and air that suppresses the deterioration of reliability due to the retention of refrigerating machine oil and reduces the discomfort of the user due to insufficient / excessive cooling capacity and the generation of refrigerant noise. The purpose is to provide a harmonizer.

In the disclosed aspect, the air conditioner has a refrigerant circuit in which an outdoor unit and a plurality of indoor units are connected by a refrigerant pipe, and the refrigerant circulates in the refrigerant circuit to install each indoor unit. Perform cooling operation. Then, in the oil recovery operation of recovering the refrigerating machine oil discharged from the compressor of the outdoor unit to the refrigerant circuit to the compressor, the air conditioner sets the expansion valve for controlling the refrigerant flow rate of the indoor unit to the first predetermined opening. It has a control means for performing the first control for performing control for opening and reducing the indoor fan rotation rate to a low rotation rate for each of a part of the indoor units among the plurality of indoor units.

The disclosed air conditioner can reduce user discomfort due to insufficient / excessive cooling capacity and generation of refrigerant noise while suppressing a decrease in reliability due to retention of refrigerating machine oil.

It is explanatory drawing of the air conditioner which is an embodiment of this invention, (A) is a refrigerant circuit diagram, (B) is a block diagram of an outdoor unit control means and an indoor unit control means. It is a 1st flowchart which shows the flow of the process which concerns on an oil recovery operation. It is a 2nd flowchart which shows the flow of the process which concerns on an oil recovery operation.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. As an embodiment, an air conditioner in which a plurality of indoor units are connected in parallel to one outdoor unit by a refrigerant pipe and all the indoor units can be simultaneously cooled or heated will be described as an example. The present invention is not limited to the following embodiments, and various modifications can be made without departing from the gist of the present invention.

FIG. 1 is an explanatory diagram of an air conditioner according to an embodiment of the present invention, (A) is a refrigerant circuit diagram, and (B) is a block diagram of an outdoor unit control means and an indoor unit control means. As shown in FIG. 1, the air conditioner 1 in the present embodiment has one outdoor unit 2 installed outdoors in a room which is an air-conditioned space, and a liquid pipe 8 and a gas in the outdoor unit 2 installed indoors. It includes 20 indoor units 5 having the same capacity connected in parallel by the pipe 9 and the electrical wiring 10. Specifically, one end of the liquid pipe 8 is connected to the closing valve 25 of the outdoor unit 2, and the other end of the liquid pipe 8 is branched and connected to the liquid pipe connecting portion 53 of each indoor unit 5. One end of the gas pipe 9 is connected to the closing valve 26 of the outdoor unit 2, and the other end of the gas pipe 9 is branched and connected to the gas pipe connecting portion 54 of each indoor unit 5. In this way, the outdoor unit 2 and the 20 indoor units 5 are connected to form the refrigerant circuit 100 of the air conditioner 1. Further, one end of the electric wiring 10 is connected to the communication unit 230 of the outdoor unit 2 described later, and the other end of the electric wiring 10 is branched and connected to the communication unit 530 of each indoor unit 5 described later. Note that FIG. 1A shows only three indoor units 5 out of the 20 indoor units 5. Further, the number of indoor units 5 may be a plurality of units other than 20 units.

First, the outdoor unit 2 will be described. The outdoor unit 2 is connected to 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 a liquid pipe 8 is connected, and one end of a gas pipe 9. It is provided with a closing valve 26, an accumulator 28, and an outdoor fan 27. Then, each of these devices except the outdoor fan 27 is connected to each other by each refrigerant pipe described in detail below to form an outdoor unit refrigerant circuit 20 forming a part of the refrigerant circuit 100.

The compressor 21 is a variable capacity compressor whose operating capacity can be changed 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 the port a of the 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 done.

The four-way valve 22 is a valve for switching the flow direction of the refrigerant, and includes four ports a, b, c, and d. As described above, the port a is connected to the refrigerant discharge side of the compressor 21 by a discharge pipe 41. The port b is connected to one of the refrigerant inlets and outlets 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 the outside air taken into the outdoor unit 2 by the rotation of the 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 when the air conditioner 1 is performing heating operation, that is, when the outdoor heat exchanger 23 functions as an evaporator, the compressor 21 detected by the discharge temperature sensor 33 described later By adjusting the opening degree according to the discharge temperature of the above, the discharge temperature does not exceed the upper limit of the performance. Further, when the air conditioner 1 is performing the cooling operation, that is, when the outdoor heat exchanger 23 functions as a condenser, the opening degree thereof is fully opened.

The outdoor fan 27 is made of a resin material and is arranged in the vicinity of the outdoor heat exchanger 23. The outdoor fan 27 takes in outside air from a suction port (not shown) into the inside of the outdoor unit 2 by rotating by a fan motor (not shown), and exchanges heat with the refrigerant in the outdoor heat exchanger 23 from an outlet (not shown). It is released to the outside of.

As described above, in the accumulator 28, the refrigerant inflow side is connected to the port c of the four-way valve 22 by the refrigerant pipe 46, and the refrigerant outflow side is connected to the refrigerant suction side of the compressor 21 by 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, the discharge pipe 41 has a discharge pressure sensor 31 that detects the pressure of the refrigerant discharged from the compressor 21 and a discharge temperature that detects the temperature of the refrigerant discharged from the compressor 21. A sensor 33 is provided. In the vicinity of 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 Is provided.

For detecting 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 between the outdoor heat exchanger 23 and the outdoor expansion valve 24 in the outdoor unit liquid pipe 44. A heat exchange temperature sensor 35 is provided. An outside air temperature sensor 36 for detecting the temperature of the outside air flowing into the inside of the outdoor unit 2, that is, the outside air temperature is provided in the vicinity of the suction port (not shown) of the outdoor unit 2.

Further, the outdoor unit 2 is provided with an outdoor unit control means 200. The outdoor unit control means 200 is mounted on a control board housed 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 is composed of a ROM and a RAM, and stores the control program of the outdoor unit 2, the detection value corresponding to the detection signals from various sensors, the control state of the compressor 21 and the outdoor fan 27, and the like. The communication unit 230 is an interface for communicating with each indoor unit 5. The sensor input unit 240 captures the detection results of the various sensors of the outdoor unit 2 and outputs the detection results to the CPU 210.

The CPU 210 captures the detection results of each sensor of the outdoor unit 2 described above via the sensor input unit 240. Further, the CPU 210 captures a control signal to be described later transmitted from each indoor unit 5 via the communication unit 230 and the electrical wiring 10. The CPU 210 controls the drive of the compressor 21 and the outdoor fan 27 based on the captured detection result and control signal. Further, the CPU 210 performs switching control of the four-way valve 22 based on the captured detection result and the control signal. Further, the CPU 210 adjusts the opening degree of the outdoor expansion valve 24 based on the captured detection result and the control signal. Further, the CPU 210 sends a control signal to each indoor unit 5 via the electric wiring 10 based on the captured detection result and the control signal.

Next, 20 indoor units 5 will be described. In the 20 indoor units 5, the indoor heat exchanger 51, the indoor expansion valve 52, the liquid pipe connecting portion 53 to which the other end of the branched liquid pipe 8 is connected, and the other end of the branched gas pipe 9 are connected. The gas pipe connecting portion 54 and the indoor fan 55 are provided. Each of these devices except the indoor fan 55 is connected to each other by each refrigerant pipe described in detail below to form an indoor unit refrigerant circuit 50 that forms a part of the refrigerant circuit 100.

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

The indoor expansion valve 52 is provided in the indoor unit liquid pipe 71. The indoor expansion valve 52 is an electronic expansion valve, and when the indoor heat exchanger 51 functions as an evaporator, that is, when the indoor unit 5 performs cooling operation, the opening degree thereof is the refrigerant outlet (gas) of the indoor heat exchanger 51. The degree of refrigerant superheat at the pipe connection portion 54 side) is adjusted to be the target degree of refrigerant superheat. Further, when the indoor heat exchanger 51 functions as a condenser, that is, when the indoor unit 5 performs the heating operation, the opening degree of the indoor expansion valve 52 is the refrigerant outlet (liquid pipe connection portion) of the indoor heat exchanger 51. The degree of refrigerant supercooling on the 53 side) is adjusted to be the target degree of refrigerant supercooling. Here, the target refrigerant superheat degree and the target refrigerant supercooling degree are the refrigerant superheat degree and the refrigerant supercooling degree necessary for the indoor unit 5 to exhibit sufficient cooling capacity or heating capacity.

The indoor fan 55 is made of a resin material and is arranged in the vicinity of the indoor heat exchanger 51. The indoor fan 55 is rotated by a fan motor (not shown) to take indoor air into the indoor unit 5 from a suction port (not shown) and exchange heat with the refrigerant in the indoor heat exchanger 51 from an outlet (not shown). Release into the room.

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

Further, the indoor unit 5 is provided with an indoor unit control means 500. The indoor unit control means 500 is mounted on a control board housed in an electrical component box (not shown) of the indoor unit 5, and as shown in FIG. 1B, the CPU 510, the storage unit 520, and the communication unit 530 , The sensor input unit 540 is provided.

The storage unit 520 is composed of a ROM and a RAM, and stores a control program of the indoor unit 5, detection values corresponding to detection signals from various sensors, setting information related to air conditioning operation by the user, and the like. The communication unit 530 is an interface for communicating with the outdoor unit 2 and another indoor unit 5. The sensor input unit 540 captures the detection results of the various sensors of the indoor unit 5 and outputs the detection results to the CPU 510.

The CPU 510 captures the detection results of each sensor of the indoor unit 5 described above via the sensor input unit 540. Further, the CPU 510 captures signals including operation information and timer operation settings set by the user by operating a remote controller (not shown) via a remote controller light receiving unit (not shown). Further, the CPU 510 transmits a control signal including an operation start / stop signal and operation information (required capacity, set temperature, indoor temperature, etc.) to the outdoor unit 2 via the communication unit 530 and the electrical wiring 10, and also outdoors. A control signal including information such as discharge pressure detected by the machine 2 is received from the outdoor unit 2 via the communication unit 530 and the electrical wiring 10. The CPU 510 adjusts the opening degree of the indoor expansion valve 52 and controls the drive of the indoor fan 55 based on the captured detection result and the signal transmitted from the remote controller and the outdoor unit 2.

The control means of the present invention is composed of the outdoor unit control means 200 and the 20 indoor unit control means 500 described above. The control means of the present invention controls the oil recovery operation described later.

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 device 1 in the present embodiment will be described with reference to FIG. 1 (A). In the following description, a case where the air conditioner 1 performs a cooling operation and all the indoor units 5 operate will be described, and a detailed description will be omitted when the air conditioner 1 performs a heating operation. Further, the arrow in FIG. 1A indicates the flow of the refrigerant during the cooling operation.

As shown in FIG. 1A, when the air conditioner 1 performs the cooling operation, the CPU 210 of the outdoor unit control means 200 shows the four-way valve 22 with a solid line, that is, the ports a and b of the four-way valve 22. To communicate with each other, and to switch between port c and port d so as to communicate with each other. As a result, the refrigerant circuit 100 becomes a cooling cycle in which the outdoor heat exchanger 23 functions as a condenser and each indoor heat exchanger 51 functions as an evaporator.

The high-pressure refrigerant discharged from the compressor 21 flows through the discharge pipe 41 and flows into the four-way valve 22, and flows from the four-way valve 22 through the refrigerant pipe 43 and flows into the outdoor heat exchanger 23. The refrigerant flowing into the outdoor heat exchanger 23 exchanges heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 27 and condenses. The refrigerant flowing out from the outdoor heat exchanger 23 to the outdoor unit liquid pipe 44 is decompressed by the outdoor expansion valve 24 and flows out to the liquid pipe 8 through the closing valve 25.

The refrigerant flowing through the liquid pipe 8 flows into each indoor unit 5 via the liquid pipe connecting portion 53. The refrigerant that has flowed into each indoor unit 5 flows through the indoor unit liquid pipe 71, passes through the indoor expansion valve 52, and is depressurized. The decompressed refrigerant flows into the indoor heat exchanger 51, exchanges heat with the indoor air taken into the indoor unit 5 by the rotation of the indoor fan 55, and evaporates. In this way, the indoor heat exchanger 51 functions as an evaporator, and the indoor heat exchanger 51 exchanges heat with the refrigerant to blow out the cooled indoor air from an outlet (not shown) into each room. The room in which the machine 5 is installed is cooled.

The refrigerant flowing out of the indoor heat exchanger 51 flows through the indoor unit gas pipe 72 and flows out to the gas pipe 9 via the gas pipe connecting portion 54. The refrigerant that has flowed through the gas pipe 9 and has flowed into the outdoor unit 2 through the closing valve 26 flows in the order of the outdoor unit gas pipe 45, 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 air conditioner 1 performs the heating operation, the CPU 210 is in a state where the four-way valve 22 is indicated by a broken line, that is, the port a and the port d of the four-way valve 22 communicate with each other, and the port b and the port c communicate with each other. Switch to. As a result, the refrigerant circuit 100 becomes a heating cycle in which the outdoor heat exchanger 23 functions as an evaporator and the indoor heat exchanger 51 of each indoor unit 5 functions as a condenser.

By the way, when the air conditioner 1 performs the cooling operation or the heating operation, in each indoor unit 5, the CPU 510 of the indoor unit control means 500 detects the set temperature determined by the user and the suction temperature sensor 63, and the sensor input unit. The temperature difference of the indoor temperature taken in via 540 is calculated, and the required capacity of each indoor unit 5 based on this temperature difference is transmitted to the outdoor unit 2 via the communication unit 530.

On the other hand, the CPU 210 of the outdoor unit control means 200 that has received the required capacity of each indoor unit 5 via the communication unit 230 calculates the total required capacity which is the total value of the required capacity of each indoor unit 5, and the calculated total request. The number of revolutions of the compressor 21 for circulating the amount of refrigerant required to achieve the capacity in the refrigerant circuit 100 is determined. Then, the CPU 210 drives and controls the compressor 21 at a determined rotation speed.

As described above, when the air conditioner 1 is performing the cooling operation and there is an indoor unit 5 whose operation is stopped, the indoor expansion valve 52 of the indoor unit 5 is fully closed. The refrigerating machine oil discharged from the compressor 21 together with the refrigerant flows into each indoor unit liquid pipe 71 via the four-way valve 22, the outdoor heat exchanger 23, and the liquid pipe 8, but the refrigeration flowing into each indoor unit liquid pipe 71. Of the machine oil, the refrigerating machine oil that has flowed into the indoor unit liquid pipe 71 provided with the indoor expansion valve 52 that is fully closed is blocked by the indoor expansion valve 52 and stays in the indoor unit liquid pipe 71. Further, in the indoor unit 5 during operation, the gas-liquid two-phase refrigerant accompanied by the refrigerating machine oil evaporates in the indoor heat exchanger 51 and becomes a gas refrigerant, which flows to the indoor unit gas pipe 72 and the gas pipe 9. At that time, a part of the refrigerating machine oil does not flow together with the refrigerant and stays in the indoor heat exchanger 51, the indoor unit gas pipe 72, and the gas pipe 9.

Therefore, the air conditioner 1 performs an oil recovery operation for recovering the retained refrigerating machine oil to the compressor 21 during the cooling operation. The oil recovery operation performed by the air conditioner 1 includes a first oil recovery operation and a second oil recovery operation. The first oil recovery operation is the first control of the present invention, and the second oil recovery operation is the second control of the present invention. In the first oil recovery operation, the air conditioner 1 opens the opening degree of the indoor expansion valve 52 to the first predetermined opening degree and rotates the indoor fan 55 for each of the indoor units 5 under certain conditions. Let the number be low rotation speed. Here, the first predetermined opening degree is a sufficient opening degree for flowing a wet refrigerant through the gas pipe 9, and is, for example, fully open. Further, the low rotation speed is a rotation speed sufficiently low for flowing a wet refrigerant through the gas pipe 9, and may be, for example, 0 rpm, that is, the fan may be stopped. In the second oil recovery operation, the air conditioner 1 increases the rotation speed of the compressor 21 to a predetermined rotation speed and opens the opening degree of the indoor expansion valve 52 to the second predetermined opening speed until a predetermined end condition is satisfied. The operation is carried out every T # 1 for the first predetermined time. Here, the predetermined termination condition is, for example, that the degree of superheat of the compressor suction refrigerant becomes zero. Further, T # 1 is determined by the amount of oil discharged from the compressor per hour, the length of the connecting pipe, etc., and is the time when it is confirmed that the amount of oil required for the compressor 21 can be maintained without performing the oil recovery operation. is there. The second predetermined opening degree is a sufficient opening degree for flowing a wet refrigerant through the gas pipe 9, and is, for example, fully open. The second predetermined opening may be the same as or different from the first predetermined opening. During the heating operation, the temperature of the gas pipe 9 is high and the viscosity of the oil is lowered, so that the oil easily returns to the compressor 21. Therefore, during the heating operation, the air conditioner 1 is less required to perform the oil recovery operation as described above.

In the first oil recovery operation, the air conditioner 1 opens the indoor expansion valve 52 to the first predetermined opening to increase the refrigerant flow rate, and sets the rotation speed of the indoor fan 55 to a low rotation speed to reduce the rotation speed of the indoor heat exchanger. Since the evaporation of the refrigerant in the indoor unit 51 can be suppressed, the refrigerating machine oil that has been blocked by the indoor expansion valve 52 and has accumulated in the indoor unit liquid pipe 71 is flushed, and the indoor heat exchanger 51, the indoor unit gas pipe 72, and the gas The amount of liquid-phase refrigerant flowing through the pipe 9 increases. As a result, the refrigerating machine oil can flow together with the moist refrigerant, and the retention of the refrigerating machine oil can be suppressed. Further, in the first oil recovery operation, the air conditioner 1 recovers only a part of the indoor units 5, so that the fluctuation of the refrigerant flow rate can be suppressed as compared with the case where all the units recover the oil at the same time, and the cooling capacity. Can suppress the shortage / excess of oil. Here, some of the indoor units 5 are, for example, 5 out of 20 connected units. Further, in the first oil recovery operation, the air conditioner 1 recovers the oil only for a part of the indoor units 5, so that the refrigerant is not insufficient as compared with the case where all the units recover the oil at the same time (in the indoor expansion valve 52). Since the upstream does not become a two-phase refrigerant), the generation of refrigerant noise can be suppressed. Therefore, by the first oil recovery operation, the air conditioner 1 can reduce the discomfort of the user while suppressing the deterioration of reliability.

Further, when the indoor unit 5 stops the operation, the air conditioner 1 performs the first oil recovery operation by using the stopped indoor unit 5 as a part of the indoor units 5. Here, the time when the indoor unit 5 stops the operation is from the time when the stop instruction is received from the remote controller or the like until the operation of the indoor unit 5 is stopped, and the air conditioner 1 recovers the first oil during this period. Start operation. When the first oil recovery operation is performed on the indoor unit 5 during operation, the cooling capacity is lowered due to the low rotation speed of the indoor fan 55, and the user feels uncomfortable. On the other hand, by performing the first oil recovery operation on the indoor unit 5 to be stopped, the air conditioner 1 can eliminate the discomfort of the user due to the fluctuation of the cooling capacity. Further, by performing the first oil recovery operation for the stopped indoor unit 5 and not targeting the stopped indoor unit 5, the air conditioner 1 suddenly recovers oil from the stopped indoor unit 5. It is possible to eliminate the generation of refrigerant noise. Therefore, the air conditioner 1 can further reduce the discomfort of the user. When the first oil recovery operation is performed when the indoor unit 5 stops the operation, the air conditioner 1 stops the rotation of the indoor fan 55 of the indoor unit 5 to be stopped.

Further, the air conditioner 1 performs the first oil recovery operation when the indoor unit 5 is stopped, and when the indoor unit 5 which is in operation is stopped when the total operating capacity is equal to or more than a predetermined value. The reason is that since many indoor units 5 are operating when the total operating capacity is high, the influence of the indoor unit 5 stopping the operation on the refrigerant flow rate becomes relatively small, and the cooling capacity fluctuates. This is because it can be made smaller. On the contrary, if the total operation capacity is small, the influence of one indoor unit 5 when it is stopped becomes large. For example, even if 3 of the 5 indoor units in operation are stopped, 10 indoor units are in operation compared to 5 indoor units in operation (the total operating capacity is small). In the case of (the total operating capacity is large), the fluctuation of the cooling capacity is small. By reducing the fluctuation of the cooling capacity, the air conditioner 1 can further reduce the discomfort of the user.

Further, the air conditioner 1 performs the first oil recovery operation when the indoor unit 5 is stopped by the rotation operation as when the indoor unit 5 is stopped when the total operation capacity is equal to or more than a predetermined value. Here, in the rotation operation, a part of the indoor units 5 are stopped when the required total capacity exceeds the threshold required capacity, and the indoor units 5 to be stopped are changed periodically so that the operation does not run out of refrigerant. Driving to do. In the rotation operation, since the plurality of indoor units 5 are sequentially stopped, oil can be recovered from the plurality of indoor units 5 and the gas pipe 9 downstream thereof, and the retention of refrigerating machine oil can be suppressed. Further, in the rotation operation, since the indoor unit 5 having the same capacity as the indoor unit 5 to be stopped starts the operation, the fluctuation of the overall refrigerant flow rate can be reduced, and the fluctuation of the cooling capacity can be reduced. Therefore, the air conditioner 1 can further reduce the discomfort of the user while further suppressing the decrease in reliability by performing the first oil recovery operation when the indoor unit 5 is stopped by the rotation operation.

Further, the air conditioner 1 performs the first oil recovery operation when the indoor unit 5 is stopped by the rotation operation, and starts a new operation by the rotation operation after the end condition of the first oil recovery operation is satisfied. The indoor expansion valve 52 of the machine 5 is opened. The air conditioner 1 is not at the start of the first oil recovery operation, but at the end (that is, the timing at which the indoor expansion valve 52 of the indoor unit 5 to be stopped is closed). Since 52 is opened, the fluctuation of the overall refrigerant flow rate can be reduced, and the fluctuation of the cooling capacity can be reduced. Therefore, the air conditioner 1 can further reduce the discomfort of the user.

Further, the air conditioner 1 performs the first oil recovery operation when the indoor unit 5 is stopped by the rotation operation, and performs the first oil recovery operation after the condition for ending the first oil recovery operation is satisfied. The indoor expansion valve 52 of the above is closed. At this time, the air conditioner 1 starts closing the indoor expansion valve 52 of the indoor unit 5 in which the first oil recovery operation has been performed, and at the same time, starts opening the indoor expansion valve 52 of the new operation indoor unit 5 in the rotation operation. When the indoor expansion valve 52 of the indoor unit 5 in which the first oil recovery operation was performed starts to close and at the same time the indoor expansion valve 52 in the new operation indoor unit 5 in the rotation operation starts to open, the room in which the first oil recovery operation is performed At the same time as the refrigerant flow rate of the machine 5 decreases, the refrigerant flow rate of the new cab unit 5 increases. Therefore, the air conditioner 1 can make the fluctuation of the total refrigerant flow rate smaller and the fluctuation of the cooling capacity smaller. Therefore, the air conditioner 1 can further reduce the discomfort of the user.

Further, when the first oil recovery operation is performed, the air conditioner 1 lengthens the interval until the next second oil recovery operation. That is, when the first oil recovery operation is performed, the air conditioner 1 sets the second predetermined time T # 2, which is larger than the first predetermined time T # 1, as the interval until the next second oil recovery operation. When the first oil recovery operation is performed, a part of the refrigerating machine oil staying in the indoor unit 5 and the gas pipe 9 in which the first oil recovery operation is performed can be recovered by the compressor 21. Therefore, the air conditioner 1 can lengthen the interval until the next second oil recovery operation, reduce the frequency of the second oil recovery operation, and change the cooling capacity and the refrigerant generated by the second oil recovery operation. You can reduce the frequency of sounds. Therefore, the air conditioner 1 can further reduce the discomfort of the user.

Further, the air conditioner 1 sets the end condition of the first oil recovery operation as the degree of superheat of the compressor suction refrigerant becomes 0 or the predetermined oil recovery time T # 3 elapses. When the degree of superheat of the compressor intake refrigerant becomes 0 and the first oil recovery operation is completed, the air conditioner 1 resets the time count from the end of the previous second oil recovery operation. When the degree of superheat of the compressor suction refrigerant becomes 0, it means that the wet refrigerant has passed through the entire path from the indoor unit 5 in which the first oil recovery operation was performed to the suction of the compressor 21. This means that the accumulated refrigerating machine oil could be recovered in the compressor 21. Therefore, the air conditioner 1 can secure a certain amount of refrigerating machine oil in the compressor 21 without performing a second oil recovery operation for recovering the refrigerating machine oil of all the indoor units 5 and the gas pipe 9. .. Therefore, the air conditioner 1 can reset the time count from the end of the previous second oil recovery operation as the same treatment as the execution of the second oil recovery operation, and can reduce the frequency of the second oil recovery operation. It can be reduced and the fluctuation of the cooling capacity and the frequency of the refrigerant noise generated by the second oil recovery operation can be reduced. Therefore, the air conditioner 1 can further reduce the discomfort of the user.

Next, the flow of processing related to the oil recovery operation will be described. 2A and 2B are flowcharts showing a flow of processing related to the oil recovery operation. In addition, in FIG. 2A and FIG. 2B, the case where the first oil recovery operation is performed while the rotation operation is being performed will be described. As shown in FIG. 2A, the air conditioner 1 starts counting the timer # 1 and turns off the flag # 1 (step S1). Here, the timer # 1 is a count value processed by the CPU 210, and counts the time from the end of the previous second oil recovery operation. Further, the flag # 1 is a flag indicating whether or not the first oil recovery operation has been performed since the previous execution of the second oil recovery operation.

Then, the air conditioner 1 determines whether or not the cooling operation is in progress (step S2), and if the air conditioning device 1 is not in the cooling operation (step S2-No), the process ends. On the other hand, when the cooling operation is in progress (step S2-Yes), the air conditioner 1 determines whether or not the flag # 1 is OFF (step S3), and when the flag # 1 is OFF. (Step S3-Yes) determines whether timer # 1 is larger than T # 1 (step S4).

Then, when the timer # 1 is larger than T # 1 (step S4-Yes), the air conditioner 1 performs the second oil recovery operation. That is, the air conditioner 1 raises the compressor rotation speed to a predetermined rotation speed and opens the indoor expansion valve 52 to the second predetermined opening degree (step S6). Then, the air conditioner 1 determines whether or not the predetermined end condition is satisfied (step S7), and if the predetermined end condition is not satisfied (step S7-No), determines in step S7. repeat. Then, when the predetermined end condition is satisfied (step S7-Yes), the air conditioner 1 resets the timer # 1, turns off the flag # 1, and sets the compressor rotation speed and the opening degree of the indoor expansion valve 52. Is returned to the state before the start of the second oil recovery operation (step S8). Then, the air conditioner 1 returns to step S2.

On the other hand, if the flag # 1 is not OFF in step S3 (step S3-No), the air conditioner 1 determines whether the timer # 1 is larger than T # 2 (step S5). Then, when the timer # 1 is larger than T # 2 (step S5-Yes), the air conditioner 1 proceeds to step S6.

Further, when the timer # 1 is not larger than T # 1 in step S4 (step S4-No), or when the timer # 1 is not larger than T # 2 in step S5 (step S5-No), air conditioning is performed. The device 1 determines whether or not to change the indoor unit to be stopped by the rotation operation (step S9). The condition of the determination is, for example, whether or not a predetermined time has elapsed since the last time the indoor unit to be stopped was changed. Then, when the indoor unit to be stopped is not changed (step S9-No), the air conditioner 1 returns to step S2.

On the other hand, when changing the indoor unit to be stopped (step S9-Yes), the air conditioner 1 carries out the first oil recovery operation. That is, the air conditioner 1 stops the rotation of the indoor fan 55 with respect to the indoor unit 5 newly stopped by the rotation operation, and opens the indoor expansion valve 52 to the first predetermined opening degree (step S10). Then, the air conditioner 1 starts counting the timer # 2 (step S11). Here, the timer # 2 is a count value processed by the CPU 210, and counts the time from the start of the first oil recovery operation.

Then, the air conditioner 1 determines whether or not the degree of superheat of the compressor intake refrigerant is 0 (step S12), and if it is 0 (step S12-Yes), resets the timer # 1 (step S12-Yes). Step S13). Then, the air conditioner 1 opens the indoor expansion valve 52 of the new operation indoor unit 5 by the rotation operation, and closes the indoor expansion valve 52 of the indoor unit 5 that has performed the first oil recovery operation (step S15). Then, the air conditioner 1 resets the timer # 2, stops the counting of the timer # 2, turns on the flag # 1 (step S16), and returns to the step S2.

On the other hand, when the degree of superheat of the compressor suction refrigerant is not 0 (step S12-No), the air conditioner 1 determines whether the timer # 2 is larger than T # 3 (step S14), and T # If it is not larger than 3 (step S14-No), the process returns to step S12. On the other hand, when the timer # 2 is larger than T # 3 (step S14-Yes), the air conditioner 1 moves to step S15.

As described above, the air conditioner 1 of the present embodiment opens the opening degree of the indoor expansion valve 52 to the first predetermined opening degree and sets the rotation speed of the indoor fan 55 to a low rotation speed in a part of the room. The first oil recovery operation to be carried out for each machine 5 is performed. The air conditioner 1 opens the opening degree of the indoor expansion valve 52 to the first predetermined opening degree to increase the refrigerant flow rate, and reduces the rotation speed of the indoor fan 55 to a low rotation speed so that the refrigerant in the indoor heat exchanger 51 The refrigerating machine oil, which was blocked by the indoor expansion valve 52 and stayed in the indoor unit liquid pipe 71, flows to the indoor heat exchanger 51, the indoor unit gas pipe 72, and the gas pipe 9. The liquid phase refrigerant is increased, and the refrigerating machine oil is allowed to flow together with the moist refrigerant to suppress the retention of the refrigerating machine oil. Further, since the air conditioner 1 recovers the oil for each of the indoor units 5, the insufficient / excessive cooling capacity and the generation of refrigerant noise are suppressed as compared with the case where the oil is recovered for all the indoor units at the same time. Therefore, the air conditioner 1 can reduce the discomfort of the user while suppressing the decrease in reliability.

Further, since the air conditioner 1 performs the first oil recovery operation for the indoor unit 5 that is stopped when the indoor unit 5 is stopped, the fluctuation of the cooling capacity is suppressed and the indoor unit 5 that has been stopped is suppressed. Prevents the noise of the refrigerant generated when recovering oil from the air. As a result, the air conditioner 1 can further reduce the discomfort of the user.

Further, when the indoor unit 5 in operation is stopped when the total operating capacity is equal to or higher than a predetermined value, the air conditioner 1 performs the first oil recovery operation for the indoor unit 5 to be stopped, so that the cooling capacity of the air conditioner 1 can be increased. Fluctuations can be reduced. As a result, the air conditioner 1 can further reduce the discomfort of the user.

Further, when the indoor unit 5 is stopped by the rotation operation, the air conditioner 1 performs the first oil recovery operation for the stopped indoor unit 5 and the gas pipe 9 downstream thereof, so that the retention of refrigerating machine oil is suppressed. At the same time, the fluctuation of the cooling capacity can be reduced. As a result, the air conditioner 1 can further reduce the discomfort of the user while further suppressing the decrease in reliability.

Further, when the air conditioner 1 performs the first oil recovery operation on the indoor unit 5 that is stopped by the rotation operation, after the condition for ending the first oil recovery operation is satisfied, the new operation indoor unit 5 in the rotation operation Since the indoor expansion valve 52 is opened, the fluctuation of the cooling capacity can be reduced. As a result, the air conditioner 1 can further reduce the discomfort of the user.

Further, the air conditioner 1 starts to close the indoor expansion valve 52 of the indoor unit 5 in which the first oil recovery operation is performed, and at the same time, starts to open the indoor expansion valve 52 of the new operation indoor unit 5 in the rotation operation. The fluctuation of ability can be made smaller. As a result, the air conditioner 1 can further reduce the discomfort of the user.

Further, when the first oil recovery operation is performed, the air conditioner 1 lengthens the interval until the next second oil recovery operation, so that the frequency of the second oil recovery operation is reduced and the second oil recovery operation is performed. It is possible to reduce the frequency of fluctuations in cooling capacity and refrigerant noise caused by the oil. As a result, the air conditioner 1 can further reduce the discomfort of the user.

Further, when the degree of superheat of the compressor intake refrigerant becomes 0 and the first oil recovery operation is completed, the air conditioner 1 resets the time count from the end of the previous second oil recovery operation. As a result, the air conditioner 1 can reduce the frequency of the second oil recovery operation and further reduce the discomfort of the user.

In the present embodiment, the case where the indoor unit 5 is provided with the indoor expansion valve 52 has been described, but the air conditioner uses an expansion valve for controlling the flow rate of the refrigerant in the indoor unit, for example, a refrigerant in each indoor unit of the liquid pipe. Immediately after branching so as to be distributed, each indoor unit may be provided in association with it.

1 Air conditioner 2 Outdoor unit 5 Indoor unit 8 Liquid pipe 9 Gas pipe 10 Electrical wiring 21 Compressor 31 Discharge pressure sensor 33 Discharge temperature sensor 52 Indoor expansion valve 55 Indoor fan 71 Indoor unit liquid pipe 72 Indoor unit Gas pipe 100 Refrigerant circuit 200 Outdoor unit control means 210 CPU
220 Storage unit 230 Communication unit 240 Sensor input unit 500 Indoor unit control means 510 CPU
530 Communication Department

Claims (8)

An air conditioner that has a refrigerant circuit in which an outdoor unit and a plurality of indoor units are connected by a refrigerant pipe, and the refrigerant circulates in the refrigerant circuit to cool an air-conditioned space in which each indoor unit is installed. ,
In the oil recovery operation of recovering the refrigerating machine oil discharged from the compressor of the outdoor unit to the refrigerant circuit to the compressor, the expansion valve that controls the refrigerant flow rate of the indoor unit is opened to the first predetermined opening and the indoor fan. An air conditioner comprising a control means for performing the first control for performing control for setting the rotation speed to a low rotation rate for each of a part of the indoor units among the plurality of indoor units. The control means
The air conditioner according to claim 1, wherein when the operation of the indoor unit is stopped, the indoor unit to be stopped is used as a part of the indoor unit to perform the first control. The control means
The air conditioner according to claim 2, wherein the first control is performed when the operation of the indoor units during operation is stopped when the total operating capacity of the plurality of indoor units is equal to or greater than a predetermined value. The control means
When the required total capacity exceeds the threshold required capacity, the stopped indoor unit is stopped, and the rotation operation, which is an operation of periodically changing the stopped indoor unit, is performed.
The air conditioner according to claim 3, wherein the first control is performed when the operation of the indoor unit is stopped by the rotation operation. The control means
The air conditioner according to claim 4, wherein the expansion valve for controlling the refrigerant flow rate of the new operating indoor unit in the rotation operation is opened after the condition for ending the first control is satisfied. The control means
After the end condition of the first control is satisfied, the expansion valve that controls the refrigerant flow rate of the indoor unit that performed the first control starts to close, and at the same time, the expansion valve that controls the refrigerant flow rate of the new operation indoor unit starts to open. The air conditioner according to claim 5, wherein the air conditioner. The control means
The second control is performed to perform the control of opening all the expansion valves that control the refrigerant flow rate of the indoor unit to the second predetermined opening at the first predetermined time by setting the compressor at a predetermined rotation speed. If the first control is performed between the second control and the elapse of the first predetermined time, the time until the next second control is changed to a second predetermined time longer than the first predetermined time. The air conditioner according to any one of claims 1 to 6, wherein the air conditioner. Further, the suction pressure detecting means for detecting the suction pressure which is the pressure of the refrigerant sucked into the compressor and the suction temperature detecting means for detecting the suction temperature which is the temperature of the refrigerant sucked into the compressor are provided.
The control means
When the superheat degree of the intake refrigerant of the compressor becomes 0, or when the predetermined oil recovery time elapses, the first control is terminated, and when the superheat degree becomes 0 and the first control is terminated, the first control is terminated. The air conditioner according to claim 7, wherein the time count from the previous second control to the elapse of the first predetermined time is reset.

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