阅读说明：本技术 空调装置的控制方法及空调装置 (Control method of air conditioner and air conditioner ) 是由 今任尚希 三浦贤 永井宏幸 于 2018-01-17 设计创作，主要内容包括：空调装置(1)的控制方法包括：使制冷剂经由制冷剂配管(4)在室外单元(2)与多个室内单元之间(3)循环的步骤；获取各个室内单元(3)的运行状态的步骤；判定室外单元(2)的压缩机(5)的油量是否下降了的步骤；以及在判定为油量下降了的情况下,判定是打开仅与运行中的室内单元(3)对应的膨胀阀(13)来进行油回收运行、还是打开与所有的室内单元(3)对应的膨胀阀(13)来进行油回收运行的步骤。(A method for controlling an air conditioner (1) comprises: circulating a refrigerant between an outdoor unit (2) and a plurality of indoor units (3) via refrigerant pipes (4); a step of acquiring the operating state of each indoor unit (3); determining whether or not the oil amount of the compressor (5) of the outdoor unit (2) has decreased; and a step of determining whether to perform an oil recovery operation by opening only the expansion valves (13) corresponding to the operating indoor units (3) or to perform an oil recovery operation by opening the expansion valves (13) corresponding to all the indoor units (3) when it is determined that the amount of oil has decreased.)

1. A control method of an air conditioner, comprising:

circulating a refrigerant between an outdoor unit and a plurality of indoor units via refrigerant pipes;

acquiring the operating state of each indoor unit;

determining whether an oil amount of a compressor of the outdoor unit is decreased; and

and determining whether to perform an oil recovery operation by opening only the expansion valves corresponding to the operating indoor units or to perform an oil recovery operation by opening the expansion valves corresponding to all the operating indoor units, when it is determined that the amount of oil has decreased.

2. The control method of an air conditioner according to claim 1, comprising:

determining whether or not an operation rate of the indoor unit is equal to or higher than a threshold value when it is determined that the oil amount has decreased;

opening only an expansion valve corresponding to the operating indoor unit to perform an oil recovery operation when it is determined that the operation rate is equal to or greater than a threshold value; and

and a step of opening the expansion valves corresponding to all the indoor units to perform an oil recovery operation when it is determined that the operation rate is less than a threshold value.

3. The control method of an air conditioner according to claim 2,

the threshold value is 20% -40%.

4. The control method of an air conditioner according to claim 2,

the operation rate is a ratio of the total capacity of the indoor units in operation to the total capacity of all the indoor units connected to the outdoor unit via the refrigerant pipe.

5. The control method of an air conditioner according to claim 1, comprising:

determining whether to perform an oil recovery operation by opening only the expansion valves corresponding to the operating indoor units or to perform an oil recovery operation by opening the expansion valves corresponding to all the indoor units when it is determined that the amount of oil has decreased at the 1 st time, and performing an oil recovery operation corresponding to the determination; and

and a step of opening the expansion valves corresponding to all the indoor units to perform an oil recovery operation when it is determined that the amount of oil has decreased after the 2 nd time.

6. An air conditioning apparatus, comprising:

an outdoor unit; a plurality of indoor units; a refrigerant pipe that circulates a refrigerant between the outdoor unit and the indoor unit; a compressor compressing a refrigerant; an oil amount detection circuit that detects an oil amount of the compressor; expansion valves respectively corresponding to the indoor units; and a control part for controlling the operation of the motor,

the control unit acquires an operation state of each of the indoor units, determines whether or not an oil amount of the compressor has decreased based on detection performed by the oil amount detection circuit,

when it is determined that the amount of oil has decreased, it is further determined whether the oil recovery operation is performed by opening only the expansion valves corresponding to the operating indoor units or the oil recovery operation is performed by opening the expansion valves corresponding to all the indoor units.

7. The air conditioner according to claim 6,

the control unit further determines whether or not the operation rate of the indoor unit is equal to or higher than a threshold value when determining that the oil amount has decreased,

when it is determined that the operation rate is equal to or greater than a threshold value, the expansion valves corresponding to only the operating indoor units are opened to perform the oil recovery operation, and when it is determined that the operation rate is less than the threshold value, the expansion valves corresponding to all the indoor units are opened to perform the oil recovery operation.

Technical Field

The embodiment of the invention relates to an air conditioner control method and an air conditioner.

Background

In the air-conditioning apparatus, oil used for lubricating the compressor of the outdoor unit is discharged from the compressor together with the refrigerant, and flows to the indoor unit through the refrigerant pipe. The oil may be retained in the refrigerant piping and not returned to the compressor. Therefore, an oil recovery operation of returning oil to the compressor is performed. In such an oil recovery operation, the expansion valves corresponding to all the indoor units including the stopped indoor unit are opened, and the rotation speed of the compressor is set higher than that in the normal operation.

Disclosure of Invention

Technical problem to be solved by the invention

When the oil recovery operation is performed, a sound (noise) of the refrigerant flowing out of the stopped indoor unit is generated, and thus, the comfort of the user located indoors is impaired. In particular, when noise is suddenly generated from the indoor unit which is in a quiet stop, the noise is very unpleasant. Therefore, it is desirable to reduce the frequency of the oil recovery operation using the indoor unit that is stopped.

An embodiment of the present invention has been made in view of the above circumstances, and an object thereof is to provide a control method of an air conditioner and an air conditioner that can reduce the frequency of noise generation from an indoor unit that is stopped when an oil recovery operation is performed.

Technical scheme for solving technical problem

The control method of the air conditioner according to the embodiment of the invention comprises the following steps: circulating a refrigerant between an outdoor unit and a plurality of indoor units via refrigerant pipes; acquiring the operating state of each indoor unit; determining whether an oil amount of a compressor of the outdoor unit is decreased; and determining whether to perform an oil recovery operation by opening only the expansion valves corresponding to the operating indoor units or to perform an oil recovery operation by opening the expansion valves corresponding to all the indoor units, when it is determined that the amount of oil has decreased.

The control method of the air conditioner according to the embodiment of the invention comprises the following steps: determining whether or not an operation rate of the indoor unit is equal to or higher than a threshold value when it is determined that the oil amount has decreased; opening only an expansion valve corresponding to the operating indoor unit to perform an oil recovery operation when it is determined that the operation rate is equal to or greater than a threshold value; and a step of opening the expansion valves corresponding to all the indoor units to perform an oil recovery operation when it is determined that the operation rate is less than a threshold value.

In the method of controlling an air conditioner according to the embodiment of the present invention, the threshold value is 20% to 40%.

In the control method of an air conditioning apparatus according to an embodiment of the present invention, the operation rate is a ratio of a total capacity of the indoor units in operation to a total capacity of all the indoor units connected to the outdoor unit via the refrigerant pipe.

The control method of the air conditioner according to the embodiment of the invention comprises the following steps: determining whether to perform an oil recovery operation by opening only the expansion valves corresponding to the operating indoor units or to perform an oil recovery operation by opening the expansion valves corresponding to all the indoor units when it is determined that the amount of oil has decreased at the 1 st time, and performing an oil recovery operation corresponding to the determination; and a step of opening the expansion valves corresponding to all the indoor units to perform an oil recovery operation when it is determined that the amount of oil has decreased after the 2 nd time.

An air conditioning apparatus according to an embodiment of the present invention includes an outdoor unit, a plurality of indoor units, refrigerant piping for circulating a refrigerant between the outdoor unit and the indoor units, a compressor for compressing the refrigerant, an oil amount detection circuit for detecting an amount of oil in the compressor, expansion valves corresponding to the indoor units, and a control unit for acquiring an operation state of each of the indoor units, determining whether the amount of oil in the compressor has decreased based on detection performed by the oil amount detection circuit, and further determining whether to perform an oil recovery operation by opening only the expansion valve corresponding to the indoor unit in operation or to perform an oil recovery operation by opening the expansion valves corresponding to all the indoor units when it is determined that the amount of oil has decreased.

In the air conditioning apparatus according to the embodiment of the present invention, the control unit further determines whether or not the operation rate of the indoor unit is equal to or higher than a threshold value when determining that the amount of oil has decreased, opens only the expansion valves corresponding to the indoor units in operation to perform the oil recovery operation when determining that the operation rate is equal to or higher than the threshold value, and opens the expansion valves corresponding to all the indoor units to perform the oil recovery operation when determining that the operation rate is lower than the threshold value.

Drawings

Fig. 1 is a structural view showing an air conditioner.

Fig. 2 is a flowchart showing a main control process performed by the outdoor unit control section.

Fig. 3 is a flowchart showing an oil recovery operation process performed by the outdoor unit control section.

Detailed Description

Hereinafter, embodiments of a control method of an air conditioner will be described in detail with reference to the drawings. Reference numeral 1 in fig. 1 denotes an air conditioner. The air conditioner 1 includes an outdoor unit 2 and a plurality of indoor units 3.

In the air conditioning apparatus 1 of the present embodiment, a plurality of indoor units 3 are connected to 1 outdoor unit 2. In addition, the outdoor unit 2 is disposed outdoors. Further, each indoor unit 3 is provided in a corresponding room to perform air conditioning of the rooms.

The outdoor unit 2 and the plurality of indoor units 3 are connected via refrigerant pipes 4 through which a refrigerant circulates. Then, a refrigeration cycle is configured by circulating a refrigerant between the outdoor unit 2 and the plurality of indoor units 3.

In the present embodiment, the flow of the refrigerant during the cooling operation is exemplified. The refrigerant pipe 4 through which the refrigerant flows from the outdoor unit 2 to the indoor unit 3 is a liquid-side pipe 4a, and the refrigerant pipe 4 through which the refrigerant flows from the indoor unit 3 to the outdoor unit 2 is a gas-side pipe 4 b.

In fig. 1, 4 indoor units 3 are illustrated, but 5 or more indoor units 3 may be connected to 1 outdoor unit 2 via the refrigerant pipe 4.

The outdoor unit 2 includes a compressor 5 that compresses a refrigerant, an outdoor heat exchanger 6 that exchanges heat between the refrigerant and outdoor air, an outdoor fan 7 that sends air to the outdoor heat exchanger 6, a four-way valve 8 that switches the flow direction of the refrigerant between a cooling operation and a heating operation, an oil amount detection circuit 9 that detects the amount of oil used for lubrication of the compressor 5, and an outdoor unit controller 10 that controls the outdoor unit 2. The outdoor unit 2 may be provided with other devices.

The indoor unit 3 includes an indoor heat exchanger 11 that exchanges heat between the refrigerant and indoor air, an indoor fan 12 that sends air to the indoor heat exchanger 11 and blows the air out into a room to be air-conditioned, an electric expansion valve 13 that expands the refrigerant, and an indoor unit control unit 14 that controls the indoor unit 3. Further, a remote controller for operating the indoor unit 3 by a user of the room and a temperature sensor for detecting the temperature of the room are connected to the indoor unit control unit 14.

Each indoor unit 3 can individually control the operation or the stop. The operation or stop of the indoor unit 3 is controlled by a user operating a remote controller. Further, in the case where the detection value of the temperature sensor does not reach the target temperature, the indoor unit 3 is operated. On the other hand, when the detection value of the temperature sensor reaches the target temperature, the indoor unit 3 is stopped. The control is executed by the indoor-unit control unit 14 or the outdoor-unit control unit 10.

In the present embodiment, a control method in the cooling operation is exemplified for description. During the cooling operation, the refrigerant is discharged from the compressor 5 of the outdoor unit 2 in a high-temperature high-pressure gas state and flows into the outdoor heat exchanger 6. The refrigerant is condensed by heat exchange with outdoor air in the outdoor heat exchanger 6, becomes liquid, and flows through the liquid-side pipe 4 a. Then, in each indoor unit 3, the liquid refrigerant flows from the liquid-side pipe 4a into the indoor heat exchanger 11 via the motor-operated expansion valve 13. The liquid refrigerant in the indoor heat exchanger 11 exchanges heat with air in a room to be air-conditioned, evaporates, and is gasified.

The refrigerant in the form of a gas discharged from the indoor heat exchanger 11 of the indoor unit 3 flows through the gas-side pipe 4 b. Then, the gaseous refrigerant is compressed by the compressor 5 of the outdoor unit 2 to become a high-temperature and high-pressure gas, and is discharged from the compressor 5 again.

In addition, the air conditioner 1 may perform a heating operation. During the heating operation, the four-way valve 8 is switched so that the refrigerant flowing through the refrigerant pipe 4 flows in the opposite direction. During the cooling operation, the outdoor heat exchanger 6 of the outdoor unit 2 is a condenser, and the indoor heat exchanger 11 of the indoor unit 3 is an evaporator, whereas during the heating operation, the outdoor heat exchanger 6 of the outdoor unit 2 is an evaporator, and the indoor heat exchanger 11 of the indoor unit 3 is a condenser.

The outdoor unit control unit 10 and each indoor unit control unit 14 are connected via a communication line 15. The indoor-unit control unit 14 transmits an operation state signal indicating whether the corresponding indoor unit 3 is in operation or in stop to the outdoor-unit control unit 10. When the indoor unit 3 is in operation, the control for opening the motor-operated expansion valve 13 is performed. When the indoor unit 3 is stopped, the electric expansion valve 13 is controlled to be closed.

The compressor 5 of the outdoor unit 2 is provided with a compression mechanism that compresses a gaseous refrigerant, and a motor that drives the compression mechanism. The compressor 5 is filled with lubricating oil for smoothly driving the compression mechanism. This oil is sometimes discharged from the compressor 5 together with the refrigerant and flows out through the refrigerant pipe 4. However, if the refrigerant in the indoor unit 3 is in a gaseous state, the oil does not flow together with the refrigerant, and in particular, adheres to and remains on the inner circumferential surface of the gas-side pipe 4 b. If such a state continues, the amount of oil in the compressor 5 decreases, which may cause a problem.

Therefore, the air conditioner 1 detects the height of the oil level inside the compressor 5 by using the oil amount detection circuit 9 at predetermined intervals, and executes the oil recovery operation when the oil amount decreases. In the oil recovery operation, the electric expansion valve 13 of the indoor unit 3 is controlled to perform a so-called liquid return operation in which the liquid refrigerant is kept in a liquid state without being gasified and is returned to the compressor 5. By performing this liquid-reflux operation, the liquid refrigerant passes through the gas-side pipe 4 b. Therefore, the oil adhering to the inner circumferential surface of the gas-side pipe 4b flows into the compressor 5 together with the refrigerant. This enables oil to be recovered.

The liquid return operation is an operation in which the opening degree of the motor-operated expansion valve 13 of the indoor unit 3 is made larger than the opening degree of the superheat control performed in a normal state, and the refrigerant in a liquid state is kept flowing through the gas side pipe 4b without being gasified.

When the oil recovery operation is performed, the electric expansion valve 13 of the indoor unit 3 is opened, and the refrigerant flows, thereby generating noise. In particular, when noise is suddenly generated from the indoor unit 3 in a quiet stop, the noise is very unpleasant.

In the air conditioning apparatus 1 of the present embodiment, the following two types of oil recovery operations can be performed: a partial open oil recovery operation in which only the motor-operated expansion valves 13 corresponding to the operating indoor units 3 are opened to perform the oil recovery operation, and a full open oil recovery operation in which all the motor-operated expansion valves 13 corresponding to all the indoor units 13 are opened to perform the oil recovery operation.

In the partial oil drain recovery operation, since oil recovery is performed without using the stopped indoor unit 3, noise is not emitted from the stopped indoor unit 3. In addition, during all the open oil recovery operations, noise is emitted from all the indoor units 3 including the stopped indoor unit 3. However, by switching the entire open oil recovery operation and the partial open oil recovery operation as appropriate according to the operation rate of the indoor unit 3 and using them, the frequency of performing the entire open oil recovery operation, that is, the frequency of noise emission from the stopped indoor unit can be reduced.

In the present embodiment, at the time when the oil amount detection circuit 9 detects a decrease in the oil amount of the compressor 5, if the operation rate of the indoor unit 3 at that time is equal to or higher than a predetermined threshold value, the oil recovery operation is performed using only the indoor unit 3 in operation. On the other hand, when the oil amount detection circuit 9 detects a decrease in the oil amount of the compressor 5 and the operation rate of the indoor unit 3 at that time is less than the predetermined threshold value, the stopped indoor unit 3 is operated and the oil recovery operation is performed using all the indoor units 3. This can reduce the frequency of opening the electric expansion valve 13 of the stopped indoor unit 3 during the oil recovery operation.

In the present embodiment, at the time when the oil amount detection circuit 9 detects a decrease in the amount of oil in the compressor 5, it is determined whether the oil recovery operation is performed by opening only the motor-operated expansion valves 13 corresponding to the operating indoor units 3 or the oil recovery operation is performed by opening the motor-operated expansion valves 13 corresponding to all the indoor units 3. Then, a preset threshold value is used for the determination.

In the present embodiment, the threshold is set to 30%. Thus, the process of determining can be performed using the threshold value, and therefore, the process of determining whether to perform the oil recovery operation using only the operating indoor units 3 or to perform the oil recovery operation using all the indoor units 3 becomes easy.

The operation rate of the indoor units 3 is a ratio of the total capacity of the indoor units 3 in operation to the total capacity of all the indoor units 3 connected to the outdoor unit 2 via the refrigerant pipe 4. Thus, the operation rate of the indoor unit 3 when returning the oil to the compressor 5 can be set according to the operation rate corresponding to the total capacity of the indoor unit 3.

The capacity of the indoor unit 3 of the present embodiment is set using at least one of the size of the indoor heat exchanger 11 and the output of the indoor fan 12. This capacity refers to the work load expressed in kilowatts. Further, the capacity corresponding to each indoor unit 3 is preset at the time of design of the indoor unit 3 according to the size of the indoor heat exchanger 11 and the output of the indoor fan 12.

In the present embodiment, the capacities of the respective indoor units 3 may be different from each other or may be the same as each other. The operation rate is determined by the following equation based on the capacity of the indoor unit 3. Here, the total capacity is a capacity obtained by summing up the capacities of the respective indoor units 3.

Operation rate [% ] is (total capacity of operating indoor units ÷ total capacity of all indoor units) × 100

For example, in the case where 10 indoor units 3 of 1 kw are provided, the total capacity of all the indoor units 3 is 10 kw. In the case where 3 indoor units 3 are operated, the total capacity is 3 kw. That is, if 3 or more indoor units 3 out of 10 indoor units 3 are in operation, the operation rate is 30% or more.

When the operation rate of the indoor unit 3 is 30% or more, even if the oil recovery operation is performed using only the indoor unit 3 in operation, a sufficient amount of oil can be recovered by 1 oil recovery operation, and the oil level of the compressor 5 can be recovered. In addition, when the operation rate of the indoor unit 3 is less than 30%, a sufficient amount of oil may not be recovered by 1 oil recovery operation.

Therefore, in the present embodiment, when the amount of oil decreases, it is determined whether the oil recovery operation is performed by opening only the motor-operated expansion valves 13 corresponding to the operating indoor units 3 or the oil recovery operation is performed by opening the motor-operated expansion valves 13 corresponding to all the indoor units 3, and the oil recovery operation corresponding to the determination is performed.

The outdoor unit control unit 10 includes a storage unit that stores the capacity of each of the indoor units 3 connected to the outdoor unit 2. In addition, when a new indoor unit 3 is connected to the outdoor unit 2 or an old indoor unit 3 is removed, the information stored in the storage unit is also updated.

The outdoor unit control unit 10 can calculate the operation rate of the indoor units 3 based on the operation state information received from the indoor unit control unit 14. The operating indoor unit 3 is determined based on the operation state signal. Then, the total capacity of the operating indoor units 3 is calculated with reference to the storage unit. In addition, the total capacity of all the indoor units 3 is calculated in advance. Then, the operation rate is calculated by obtaining the ratio of the total capacity of the operating indoor units 3 to the total capacity of all the indoor units 3.

The state of operation or stop of the indoor unit 3 is based on the state of opening and closing of the motor-operated expansion valve 13. Further, the state of operation or stop of the indoor unit 3 may be indicated based on the state of "on" or "off" of the voltage of the indoor unit 3.

In the present embodiment, when it is determined that the oil amount of the compressor 5 has decreased at the 1 st time, it is determined whether the oil recovery operation is performed by opening only the motor-operated expansion valves 13 corresponding to the operating indoor units 3 or the oil recovery operation is performed by opening the motor-operated expansion valves 13 corresponding to all the indoor units 3, and the oil recovery operation corresponding to the determination is performed.

When it is determined that the oil amount of the compressor 5 has decreased after the 2 nd time, the electric expansion valves 13 corresponding to all the indoor units 3 are opened to perform the oil recovery operation. That is, when it is determined that the oil amount has decreased after the 2 nd time, the determination of the operation rate of the indoor unit 3 is not performed.

In the case where the partial open oil recovery operation is performed in the 1 st operation and a sufficient amount of oil is not returned to the compressor 5 in the partial open oil recovery operation, the entire open oil recovery operation is always performed after the 2 nd operation. Thus, in the case where a sufficient amount of oil is not returned to the compressor 5 in the 1 st oil recovery operation, the sufficient amount of oil is returned to the compressor 5 in the 2 nd and subsequent oil recovery operations.

In the present embodiment, when the oil amount of the compressor 5 is detected to decrease again after the oil amount of the compressor 5 is detected to decrease 4 times, the outdoor unit control unit 10 restarts the outdoor unit 2. In addition, when the oil amount decrease of the compressor 5 is first detected after the restart, it is assumed that the oil amount decrease is detected for the 1 st time. That is, when a sufficient amount of oil is not returned to the compressor 5 even after 4 oil recovery operations, the outdoor unit 2 is restarted.

In the present embodiment, the outdoor unit 2 is restarted under the condition that the oil amount decrease is detected 4 times, but the condition may be other states. For example, even if the drop in the amount of oil is detected 3 times or less, the outdoor unit 2 may be restarted, and the outdoor unit 2 may be restarted on the condition that the drop in the amount of oil is detected 5 times or more. The condition of the number of times is set as appropriate depending on the configuration of the outdoor unit 2 or the number of compressors 5 mounted.

In the present embodiment, when the oil amount of the compressor 5 is detected to decrease again after the outdoor unit 2 is restarted 4 times, the outdoor unit control unit 10 outputs a failure alarm indicating that the outdoor unit 2 has failed. That is, if a sufficient amount of oil is not returned to the compressor 5 even after 4 times of restarting of the outdoor unit 2, a failure alarm is output.

In the present embodiment, the failure alarm is output under the condition that the outdoor unit 2 is restarted 4 times, but the condition may be in another state. For example, the trouble alarm may be output even if the outdoor unit 2 is restarted 3 times or less, or the trouble alarm may be output on condition that the outdoor unit 2 is restarted 5 times or more. The condition of the number of times is set as appropriate depending on the configuration of the outdoor unit 2 or the number of compressors 5 mounted.

In the present embodiment, the threshold value is set to 30%, but other threshold values may be used. For example, the threshold may be 20%, 25%, 35%, or 40%.

In addition, the applicant conducted experiments under various air conditioners 1 and installation environments. As a result, it is understood that when the oil recovery operation is performed using only the indoor unit 3 in operation, if the operation rate of the indoor unit 3 is at least 20%, oil can be sufficiently recovered. Further, it is found that if the operation rate of the indoor unit 3 is at least 30%, the oil recovery capability is further improved. Further, it is understood that if the operation rate of the indoor unit 3 is at least 40%, oil can be recovered by 1 oil recovery operation regardless of the air conditioner 1 and the installation environment.

When the threshold value is low, the frequency of operating the stopped indoor unit 3 is low in the first oil recovery operation, but the frequency of performing the oil recovery operation of the 2 nd or subsequent operation is high. On the other hand, when the threshold value is high, the frequency of operating the stopped indoor unit 3 during the first oil recovery operation is high, but the frequency of performing the oil recovery operation of the 2 nd or subsequent operation is low. That is, as is clear from the experimental results performed by the applicant, when the frequency of the operation of the indoor unit 3 and the frequency of the oil recovery operation are comprehensively considered, the threshold value is preferably 30%. That is, the threshold value may be in the range of 20 to 40%. The preferred threshold may be in the range of 25-35%.

The outdoor-unit control unit 10 and the indoor-unit control unit 14 according to the present embodiment are configured by a computer having hardware resources such as a processor and a memory, and implementing information processing using software using the hardware resources by executing various programs by a CPU. The method for controlling an air conditioner according to the present embodiment is further realized by causing a computer to execute a program.

The outdoor-unit control unit 10 and the indoor-unit control unit 14 include nonvolatile memories. The nonvolatile memory is a memory that can read only stored data and can hold the stored contents even when power supply is interrupted. The nonvolatile memory is configured by a device such as an EEPROM or a flash ROM, for example.

Next, the main process executed by the outdoor unit control unit 10 will be described with reference to the flowchart of fig. 2. The oil recovery process performed by the outdoor unit control unit 10 will be described with reference to the flowchart of fig. 3. In addition, reference is made to the structural diagram shown in fig. 1 as appropriate.

The above-described processing is repeated at predetermined time intervals. By repeating the above-described processing, the control method of the air conditioner is executed. The outdoor unit control unit 10 may interrupt the above-described process and execute the process while executing another process.

As shown in fig. 2, in the main control process, first, in step S11, the outdoor-unit control unit 10 executes a refrigerant circulation process (cooling operation) in which the refrigerant is circulated between the outdoor unit 2 and the plurality of indoor units 3 via the refrigerant pipes 4.

In the next step S12, the outdoor-unit control section 10 executes an operation-state acquisition process of acquiring the operation state of each indoor unit 3 based on the operation-state information received from the indoor-unit control section 14.

In the next step S13, the outdoor unit control unit 10 executes an oil amount detection process of detecting the oil amount of the compressor 5 using the oil amount detection circuit 9.

In the next step S14, the outdoor unit control unit 10 executes an oil recovery operation process for performing an oil recovery operation when a decrease in the amount of oil in the compressor 5 is detected. Then, the process is ended.

As shown in fig. 3, in the oil recovery operation process, first, in step S21, the outdoor unit control unit 10 determines whether the oil amount of the compressor 5 has decreased based on the oil amount detected by the oil amount detection circuit 9. Here, if the oil amount has not decreased (no in step S21), the process ends. On the other hand, if the oil amount has decreased (yes in step S21), the process proceeds to step S22.

Next, in step S22, the outdoor-unit control unit 10 determines whether or not the value of the restart counter that counts the number of times the outdoor unit 2 is restarted is "4". Here, if the restart counter value is "4" (yes at step S22), the process proceeds to step S31, which will be described later. On the other hand, if the value of the restart counter is not "4" (no at step S22), the process proceeds to step S23.

Next, in step S23, the outdoor unit control unit 10 determines whether or not the value of the oil amount decrease counter that counts the number of times the oil amount of the compressor 5 decreases is "4". Here, if the value of the oil amount decrease counter is "4" (yes at step S22), the process proceeds to step S33, which will be described later. On the other hand, if the value of the oil amount decrease counter is not "4" (no at step S23), the process proceeds to step S24.

In the next step S24, the outdoor unit control unit 10 adds "1" to the value of the oil amount decrease counter.

Next, in step S25, the outdoor unit control unit 10 determines whether or not a first flag indicating that the oil amount of the compressor 5 has been reduced to the first time is set. The first time is the first 1 st time after the outdoor unit 2 is restarted. Here, if the first flag is not set (no at the flag S25), the process proceeds to step S28 described later. On the other hand, if the first flag is set (yes at the flag S25), the process proceeds to step S26.

Next, in step S26, the outdoor-unit control unit 10 determines whether or not the operation rate of the indoor unit 3 is equal to or higher than a threshold value. Here, if the operation rate of the indoor unit 3 is equal to or higher than the threshold value (yes in step S26), the process proceeds to step S27. On the other hand, if the operation rate of the indoor unit 3 is less than the threshold value (no in step S26), the process proceeds to step S28.

In step S27, the outdoor unit control unit 10 opens only the motor-operated expansion valve corresponding to the operating indoor unit 3 to perform the partial open oil recovery operation. Then, the process proceeds to step S30 described later.

In step S28, the outdoor unit control unit 10 opens the motor-operated expansion valves 13 corresponding to all the indoor units 3 including the stopped indoor unit 3 to perform the all-open oil recovery operation. Then, the process proceeds to step S29.

Next, in step S29, the outdoor-unit control unit 10 determines whether or not the first flag is set. Here, if the first flag is not set (no in step S29), the processing is ended. On the other hand, if the first flag is set (yes at the flag S29), the process proceeds to step S30.

In the next step S30, the outdoor-unit control unit 10 clears the first flag and ends the process.

In step S31, which is advanced when the step S22 is yes, the outdoor unit control unit 10 clears the restart counter.

In the next step S32, the outdoor-unit control unit 10 executes a failure alarm output process of outputting a failure alarm indicating that the outdoor unit 2 has failed.

In step S33, which is advanced when the step S23 is yes, the outdoor-unit control unit 10 clears the oil-amount-decrease counter.

Next, in step S34, the outdoor-unit control section 10 sets a first flag.

In the next step S35, the outdoor unit control unit 10 adds "1" to the value of the restart counter.

In the next step S36, the outdoor-unit control unit 10 executes a restart process of restarting the outdoor unit 2.

In the present embodiment, the determination using the arbitrary value of the reference value (threshold value) may be a determination of "whether or not the arbitrary value is equal to or greater than the reference value", or a determination of "whether or not the arbitrary value exceeds the reference value". Alternatively, the determination may be made as to whether or not the arbitrary value is equal to or less than the reference value, or may be made as to whether or not the arbitrary value is smaller than the reference value. The reference value may be variable instead of being fixed. Therefore, it is also possible to use a value in a predetermined range instead of the reference value and determine whether or not an arbitrary value is within the predetermined range. Further, an error generated in the apparatus may be analyzed in advance, and a predetermined range including an error range may be used for the determination with the reference value as a center.

In the flowchart of the present embodiment, a mode in which each step is continuously executed is illustrated, but the context of each step is not necessarily predetermined, and the context of some steps may be replaced. Further, some steps may be executed in parallel with other steps.

The program executed by the control unit of the present embodiment is provided by being incorporated in a ROM or the like in advance. Alternatively, the program may be provided as a file in an installable or executable format stored on a computer-readable non-transitory storage medium such as a CD-ROM, a CD-R, a memory card, a DVD, or a Flexible Disk (FD).

The program executed by the control unit may be stored in a computer connected to a network such as the internet and downloaded via the network to be provided. The control unit may be configured by connecting and combining independent modules that independently function as the respective components to each other through a network or a dedicated line.

In the present embodiment, the indoor units 3 are provided with the electric expansion valves 13, but the outdoor unit 2 may be provided with electric expansion valves corresponding to the respective indoor units 3. Further, both the outdoor unit 2 and the indoor unit 3 may be provided with an electric expansion valve.

In the present embodiment, the operation rate corresponding to the capacity of the indoor unit 3 is obtained, but the operation rate corresponding to the number of indoor units 3 may be obtained.

In addition, in the present embodiment, the determination of the operation rate of the indoor unit 3 is not performed when it is determined that the amount of oil has decreased after the 2 nd time, but it is also possible to determine whether to perform the oil recovery operation by opening only the electric expansion valves 13 corresponding to the operating indoor units 3 or to perform the oil recovery operation by opening the electric expansion valves 13 corresponding to all the indoor units 13 even after the 2 nd time, and perform the oil recovery operation corresponding to the determination.

In the present embodiment, when the oil amount of the compressor 5 is decreased, the partial open oil recovery operation is performed when the operation rate of the indoor unit 3 is 30% or more, and the entire open oil recovery operation is performed when the operation rate of the indoor unit 3 is less than 30%, but other modes are also possible. For example, when the operation rate of the indoor units 3 is less than 30%, the oil recovery operation may be performed by opening only the electric expansion valves 13 corresponding to some of the indoor units 3 without opening all of the electric expansion valves 13 corresponding to all of the indoor units 3. The ratio of the total capacity of the indoor units 3 in which the motor-operated expansion valves 13 are opened at this time is controlled to be 30% or more of the total capacity of all the indoor units 3.

In the partially open oil recovery operation, when the indoor unit 3 located at the farthest position from the outdoor unit 2 and the indoor unit 3 located at the end of the refrigerant pipe 4 are stopped, the motor-operated expansion valve 13 of the indoor unit 3 may be opened. Since the liquid refrigerant returns from the indoor unit 3 located at the end of the refrigerant pipe 4, the oil adhering to the inner circumferential surface of the refrigerant pipe 4 can be efficiently recovered.

Further, a plurality of outdoor units 2 sharing the refrigerant pipe 4 may be provided, and a plurality of indoor units 3 may be connected to the outdoor units 2. Further, 2 or more compressors 5 may be provided in parallel in the outdoor unit 2.

According to the embodiment described above, the step of determining whether to perform the oil recovery operation by opening only the expansion valves corresponding to the operating indoor units or to perform the oil recovery operation by opening the expansion valves corresponding to all the indoor units is included, whereby the frequency of noise emission from the stopped indoor units can be reduced during the oil recovery operation.

Several embodiments of the present invention have been described, but these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These embodiments can be implemented in various forms, and various omissions, substitutions, changes, and combinations can be made without departing from the spirit of the invention. The above-described embodiments and modifications thereof are included in the scope and spirit of the present invention, and are included in the inventions described in the claims and the scope equivalent thereto.

Description of the reference symbols

1 air-conditioning apparatus

2 outdoor unit

3 indoor unit

4 refrigerant piping

5 compressor

6 outdoor heat exchanger

7 outdoor fan

8 four-way valve

9 oil mass detection circuit

10 outdoor unit control part

11 indoor heat exchanger

12 indoor fan

13 electric expansion valve

14 indoor unit control part

15 communication lines.