AU2021365042A1 - Air conditioner - Google Patents

Abstract

This air conditioner has a refrigerant circuit that is formed by an indoor unit having an indoor heat exchanger being connected by refrigerant piping to an outdoor unit that has a compressor, an outdoor heat exchanger and an expansion valve, the refrigerant circuit being filled with a predetermined amount of refrigerant. This air conditioner comprises: an acquisition unit that periodically acquires the quantity of operating state during air-conditioning operation; a storage unit that stores the acquired operating state quantity; an estimation model for estimating the amount of refrigerant remaining in the refrigerant circuit using the operating state quantity; a detection unit that detects, from the storage unit, a first operating state quantity in a state in which the refrigerant circuit satisfies a first stability condition, or a second operating state quantity in a state in which the refrigerant circuit satisfies a second stability condition that is different from the first stability condition; and a control unit that estimates the amount of refrigerant remaining in the refrigerant circuit using the estimation model and the detected operating state quantity. The amount of refrigerant remaining in the refrigerant circuit can be estimated even when the air conditioner is in actual operation.

Description

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DESCRIPTION TITLE OF THE INVENTION: AIR CONDITIONER

Field

[0001] The present invention relates to an air

conditioner.

Background

[0002] An air conditioner that determines a refrigerant

amount by using an operating state quantity that is

detectable by a refrigerant circuit has been proposed (for

example, Patent Literature 1). In Patent Literature 1, for

example, to achieve a state in which only a liquid

refrigerant exists (a gas refrigerant does not exist) as a

refrigerant that flows through a liquid pipe of a

refrigerant circuit at the time of cooling cycle, a

refrigerant amount is determined by using a degree of

super-cooling of the refrigerant at an outlet of a

condenser in a state in which a degree of super-heating of

the refrigerant at an outlet of an evaporator or pressure

of the evaporator is adjusted (hereinafter, this state will

be referred to as a default state).

Citation List

Patent Literature

[0003] Patent Literature 1: Japanese Laid-open Patent

Publication No. 2006-23072

Summary

Technical Problem

[0004] When an air conditioner is actually operating, it

is difficult to achieve the default state that is a

prerequisite of Patent Literature 1, so that it becomes

difficult to estimate a refrigerant amount.

[00051 In view of the foregoing situations, an object of

the present invention is to provide an air conditional that

is able to estimate a remaining refrigerant amount in a

refrigerant circuit even when the air conditioner is

actually operating.

Solution to Problem

[00061 According to an aspect of an embodiment, an air

conditioner includes a refrigerant circuit that is formed

by connecting, by a refrigerant pipe, an indoor unit

including an indoor heat exchanger to an outdoor unit

including a compressor, an outdoor heat exchanger, and an

expansion valve. The refrigerant circuit is filled with a

predetermined amount of a refrigerant. The air conditioner

includes an acquisition unit, a storage unit, an estimation

model, a detection unit and a control unit. The acquisition

unit regularly acquires an operating state quantity at a

time of air conditioning operation. The storage unit stores

therein the operating state quantity that is acquired by

the acquisition unit. The estimation model estimates a

refrigerant remaining amount in the refrigerant circuit by

using the operating state quantity. The detection unit

detects, from the storage unit, one of a first operating

state quantity and a second operating state quantity. The

first operating state quantity is an operating state

quantity in a state in which the refrigerant circuit meets

a first stability condition. The second operating state

quantity is an operating state quantity in a state in which

the refrigerant circuit meets a second stability condition

that is different from the first stability condition. The

control unit estimates the remaining refrigerant amount in

the refrigerant circuit by using the estimation model and

the operating state quantity that is detected by the

detection unit.

Advantageous Effects of Invention

[0007] According to one aspect, it is possible to estimate a remaining refrigerant amount in a refrigerant circuit even when an air conditioner is actually operating. Brief Description of Drawings

[0008] FIG. 1 is an explanatory diagram illustrating an example of an air conditioner of a present embodiment. FIG. 2 is an explanatory diagram illustrating an example of an outdoor unit and an indoor unit. FIG. 3 is a block diagram illustrating an example of a control circuit of the outdoor unit. FIG. 4 is a Mollier diagram illustrating a state of a change of a refrigerant in the air conditioner. FIG. 5 is a flowchart illustrating an example of processing operation performed by the control circuit in relation to an acquisition process. FIG. 6 is a flowchart illustrating an example of processing operation performed by the control circuit in relation to a detection process. FIG. 7 is a flowchart illustrating an example of processing operation performed by the control circuit in relation to an estimation process. FIG. 8 is an explanatory diagram illustrating an air conditioning system of a second embodiment. Description of Embodiments

[0009] Embodiments of an air conditioner and the like disclosed in the present application will be described in detail below based on the drawings. The disclosed technology is not limited by the present embodiments. In addition, each of the embodiments described below may be appropriately modified as long as no contradiction is derived.

[0010] First Embodiment

Configuration of air conditioner

FIG. 1 is an explanatory diagram illustrating an

example of an air conditioner 1 of the present embodiment.

The air conditioner 1 illustrated in FIG. 1 is, for

example, a home-use air conditioner that includes a single

outdoor unit 2 and a single indoor unit 3. The outdoor

unit 2 is connected to the indoor unit 3 by a liquid pipe 4

and a gas pipe 5. Further, a refrigerant circuit 6 of the

air conditioner 1 is formed by connecting the outdoor unit

2 and the indoor unit 3 by a refrigerant pipe, such as the

liquid pipe 4 and the gas pipe 5.

[0011] Configuration of outdoor unit

FIG. 2 is an explanatory diagram illustrating an

example of the outdoor unit 2 and the indoor unit 3. The

outdoor unit 2 includes a compressor 11, a four-way valve

12, an outdoor heat exchanger 13, an expansion valve 14, an

accumulator 15, an outdoor unit fan 16, and a control

circuit 17. With use of the compressor 11, the four-way

valve 12, the outdoor heat exchanger 13, the expansion

valve 14, and the accumulator 15, an outdoor-side

refrigerant circuit that constitutes a part of the

refrigerant circuit 6 is formed by connecting these devices

to one another by each of refrigerant pipes that will be

described in detail below.

[0012] The compressor 11 is a variable-capacity

compressor of a pressurized container type that is able to

change working capacity in accordance with drive of a motor

(not illustrated) for which a rotation speed is controlled

by an inverter, for example. A refrigerant discharge side

of the compressor 11 is connected to a first port 12A of

the four-way valve 12 by a discharge pipe 21. Further, a

refrigerant suction side of the compressor 11 is connected

to a refrigerant outflow side of the accumulator 15 by a suction pipe 22.

[0013] The four-way valve 12 is a valve for changing a direction in which a refrigerant flows in the refrigerant circuit 6, and includes the first port 12A to a fourth port 12D. The first port 12A is connected to the refrigerant discharge side of the compressor 11 by the discharge pipe 21. A second port 12B is connected to one refrigerant gate (corresponding to a first outdoor heat exchange opening 13A to be described later) of the outdoor heat exchanger 13 by an outdoor refrigerant pipe 23. A third port 12C is connected to a refrigerant inflow side of the accumulator 15 by an outdoor refrigerant pipe 26. Further, the fourth port 12D is connected to an indoor heat exchanger 51 by an outdoor gas pipe 24.

[0014] The outdoor heat exchanger 13 performs heat exchange between the refrigerant and outdoor air that is taken into the outdoor unit 2 by rotation of the outdoor unit fan 16. The outdoor heat exchanger 13 includes the first outdoor heat exchange opening 13A that serves as the one refrigerant gate, a second outdoor heat exchange opening 13B that serves as another refrigerant gate, and an outdoor heat exchange intermediate part 13C that connects the first outdoor heat exchange opening 13A and the second outdoor heat exchange opening 13B. The first outdoor heat exchange opening 13A is connected to the second port 12B of the four-way valve 12 by the outdoor refrigerant pipe 23. The second outdoor heat exchange opening 13B is connected to the expansion valve 14 by an outdoor liquid pipe 25. The outdoor heat exchange intermediate part 13C is connected to the first outdoor heat exchange opening 13A and the second outdoor heat exchange opening 13B. The outdoor heat exchanger 13 functions as a condenser when the air conditioner 1 performs cooling operation, and functions as an evaporator when the air conditioner 1 performs heating operation.

[0015] The expansion valve 14 is an electronic expansion valve that is arranged on the outdoor liquid pipe 25 and that is driven by a pulse motor (not illustrated). The expansion valve 14 adjusts an amount of a refrigerant (an amount of a refrigerant that flows from the outdoor heat exchanger 13 to the indoor heat exchanger 51 or an amount of a refrigerant that flows from the indoor heat exchanger 51 to the outdoor heat exchanger 13) that flows from the expansion valve 14 into the refrigerant circuit 6, by adjusting a degree of opening in accordance with the number of pulses given to the pulse motor. The degree of opening of the expansion valve 14 is adjusted such that temperature at which the refrigerant is discharged (refrigerant discharge temperature) by the compressor 11 reaches target discharge temperature that is predetermined temperature.

[0016] The refrigerant inflow side of the accumulator 15 is connected to the third port 12C of the four-way valve 12 by the outdoor refrigerant pipe 26. Further, the refrigerant outflow side of the accumulator 15 is connected to a refrigerant inflow side of the compressor 11 by the suction pipe 22. The accumulator 15 separates the refrigerant, which has flown from the outdoor refrigerant pipe 26 into the accumulator 15, into a gas refrigerant and a liquid refrigerant, and causes only the gas refrigerant to be sucked by the compressor 11.

[0017] The outdoor unit fan 16 is made of a resin material and is arranged in the vicinity of the outdoor heat exchanger 13. The outdoor unit fan 16 takes outdoor air into the outdoor unit 2 from a suction opening (not illustrated) in accordance with rotation of a fan motor (not illustrated), and discharges the outdoor air that is subjected to heat exchange with the refrigerant in the outdoor heat exchanger 13 to outside of the outdoor unit 2 via a discharge opening (not illustrated).

[0018] Furthermore, a plurality of sensors are arranged

in the outdoor unit 2. In the discharge pipe 21, a

discharge temperature sensor 31 that detects temperature of

the refrigerant that is discharged from the compressor 11,

that is, the refrigerant discharge temperature, is

arranged. In the outdoor liquid pipe 25 between the

outdoor heat exchanger 13 and the expansion valve 14, an

outdoor heat exchange outlet sensor 32 that detects

temperature of the refrigerant that flows into the second

outdoor heat exchange opening 13B or temperature of the

refrigerant that flows out of the second outdoor heat

exchange opening 13B among temperature of the heat

exchanger is arranged. Moreover, in the vicinity of the

suction opening (not illustrated) of the outdoor unit 2, an

outdoor air temperature sensor 33 that detects temperature

of the outdoor air that flows into the outdoor unit 2, that

is, outdoor air temperature, is arranged.

[0019] The control circuit 17 controls the outdoor unit

2 upon receiving an instruction from a control circuit 18

of the indoor unit 3 to be described later. The control

circuit 17 of the outdoor unit 2 includes a communication

unit, a storage unit, and a control unit (not illustrated).

The communication unit is a communication interface for

communicating with a communication unit 41 of the indoor

unit 3 to be described later. The storage unit is, for

example, a flash memory, and stores therein a control

program of the outdoor unit 2, operating state quantities,

such as detected values, corresponding to detection signals

from various sensors, a driving state of the compressor 11

or the outdoor unit fan 16, a rated capacity of the outdoor unit 2, a requested capacity of each of the indoor units 3, and the like.

[0020] Configuration of indoor unit As illustrated in FIG. 2, the indoor unit 3 includes the indoor heat exchanger 51, a gas pipe connection unit 52, a liquid pipe connection unit 53, an indoor unit fan 54, and the control circuit 18. The indoor heat exchanger 51, the gas pipe connection unit 52, and the liquid pipe connection unit 53 are connected to one another by each of refrigerant pipes to be described later, and form an indoor refrigerant circuit that constitutes a part of the refrigerant circuit 6.

[0021] The indoor heat exchanger 51 performs heat exchange between the refrigerant and indoor air that is taken into the indoor unit 3 from a suction opening (not illustrated) by rotation of the indoor unit fan 54. The indoor heat exchanger 51 includes a first indoor heat exchange opening 51A that serves as one refrigerant gate, a second indoor heat exchange opening 51B that serves as another refrigerant gate, and an indoor heat exchange intermediate part 51C that connects the first indoor heat exchange opening 51A and the second indoor heat exchange opening 51B. The first indoor heat exchange opening 51A is connected to the gas pipe connection unit 52 by an indoor gas pipe 56. The second indoor heat exchange opening 51B is connected to the liquid pipe connection unit 53 by an indoor liquid pipe 57. The indoor heat exchange intermediate part 51C is connected to the first indoor heat exchange opening 51A and the second indoor heat exchange opening 51B. The indoor heat exchanger 51 functions as a condenser when the air conditioner 1 performs heating operation, and functions as an evaporator when the air conditioner 1 performs cooling operation.

[0022] The indoor unit fan 54 is made of a resin material and is arranged in the vicinity of the indoor heat exchanger 51. The indoor unit fan 54 takes indoor air into the indoor unit 3 from a suction opening (not illustrated) in accordance with rotation of a fan motor (not illustrated), and discharges the indoor air that is subjected to heat exchange with the refrigerant in the indoor heat exchanger 51 to inside of a room from a discharge opening (not illustrated).

[0023] Various sensors are arranged in the indoor unit 3. In the indoor heat exchange intermediate part 51C, an indoor heat exchange intermediate sensor 58 that detects temperature of the refrigerant that passes through the indoor heat exchange intermediate part 51C, that is, indoor heat exchange intermediate temperature, among temperature of the heat exchanger is arranged.

[0024] The control circuit 18 controls the entire air conditioner 1. FIG. 3 is a block diagram illustrating an example of the control circuit 18 of the indoor unit 3. The control circuit 18 includes the communication unit 41, an acquisition unit 42, a detection unit 43, a storage unit 44, and a control unit 45. The communication unit 41 is a communication interface for communicating with the communication unit of the outdoor unit 2. The acquisition unit 42 acquires operating state quantities, such as detected values, corresponding to detection signals from the various sensors as described above. The storage unit 44 is, for example, a flash memory, and stores therein a control program of the indoor unit 3, the operating state quantities, such as detected values, corresponding to detection signals from various sensors, a driving state of the indoor unit fan 54, operation information (for example, including information on operation and stop of the compressor 11, a driving state of the outdoor unit fan 16, and the like) that is transmitted from the outdoor unit 2, the rated capacity of the outdoor unit 2, the requested capacity of each of the indoor units 3, and the like.

[0025] The storage unit 44 includes an operating state

quantity memory 61, a first operating state quantity memory

61A, and a second operating state quantity memory 61B. The

operating state quantity memory 61 stores therein all

operating state quantities that are acquired by the

acquisition unit 42. The operating state quantities are,

for example, operating state quantities at the time of

cooling operation, such as rotation speed of the compressor

11, the degree of opening of the expansion valve 14, the

refrigerant discharge temperature of the compressor 11, the

outdoor heat exchange outlet temperature, and temperature

of outdoor air, or operating state quantities at the time

of heating operation, such as the rotation speed of the

compressor 11, the degree of opening of the expansion valve

14, the refrigerant discharge temperature of the compressor

11, and the indoor heat exchange intermediate temperature.

[0026] The first operating state quantity memory 61A

stores therein a first operating state quantity among the

operating state quantities. The first operating state

quantity is an operating state quantity that indicates an

operating state at the time of air conditioning operation

in a state in which a first stability condition is met

under the circumstances in which the refrigerant stably

circulates inside the refrigerant circuit 6 while each of

values of high pressure and low pressure in the refrigerant

circuit 6 is stable. The first stability condition is that

a certain state, in which variation of the rotation speed

of the compressor 11 falls within a first predetermined

range, continues for a first predetermined period or more, and that a certain state, in which an absolute value of a difference between the refrigerant discharge temperature and the target discharge temperature of the compressor 11 is equal to or smaller than a predetermined value, continues for the first predetermined period or more. The first operating state quantity is, for example, an operating state quantity that is acquired when the variation of the rotation speed of the compressor 11 is within ±1 rps during five minutes and when the absolute value of the difference between the refrigerant discharge temperature and the target temperature of the compressor 11 falls within ±20C during five minutes, after a lapse of eight minutes since activation of the compressor 11.

[0027] The second operating state quantity memory 61B

stores therein a second operating state quantity among the

operating state quantities. The second operating state

quantity is an operating state quantity that indicates an

operating state at the time of air conditioning operation

in a state in which a second stability condition that is

different from the first stability condition is met under

the circumstances in which the refrigerant stably

circulates inside the refrigerant circuit 6. The second

stability condition is that a certain state, in which the

variation of the rotation speed of the compressor 11 falls

within a second predetermined range that exceeds the first

predetermined range, continues for the first predetermined

period or more or for a second predetermined period, which

exceeds the first predetermined period, or more. The

second operating state quantity is, for example, an

operating state quantity that is acquired when the

variation of the rotation speed of the compressor 11 is

within ±5 rps during 12 minutes, after a lapse of eight

minutes since activation of the compressor 11. Meanwhile, the second stability condition is a condition in which further variation of the rotation speed of the compressor

11 is allowed as compared to the first stability condition,

and therefore, the second operating state quantity that is

acquired under the second stability condition varies as

compared to the first operating state quantity that is

acquired under the first stability condition.

[0028] The detection unit 43 detects the first operating

state quantity from among the operating state quantities

stored in the operating state quantity memory 61, and

stores the detected first operating state quantity in the

first operating state quantity memory 61A. Further, the

detection unit 43 detects the second operating state

quantity from among the operating state quantities stored

in the operating state quantity memory 61, and stores the

detected second operating state quantity in the second

operating state quantity memory 61B.

[0029] Furthermore, the storage unit 44 stores therein

an estimation model for estimating a remaining refrigerant

amount in the refrigerant circuit 6. The estimation model

includes a cooling estimation model 62A and a heating

estimation model 62B. The cooling estimation model 62A is

a model for estimating the remaining refrigerant amount in

the refrigerant circuit 6 at the time of cooling operation.

Further, the heating estimation model 62B is a model for

estimating the remaining refrigerant amount in the

refrigerant circuit 6 at the time of heating operation.

[0030] The control unit 45 loads the detected values of

the various sensors at regular time intervals (for example,

every 30 seconds). The control unit 45 controls the entire

air conditioner 1 based on the various kinds of input

information. Further, the control unit 45 estimates the

remaining refrigerant amount by using each of the estimation models as described above.

[0031] Furthermore, the control unit 45 counts the number of detections of the first operating state quantity in a predetermined period, and estimates the remaining refrigerant amount in the refrigerant circuit 6 by using the first operating state quantity and each of the estimation models if the number of detections of the first operating state quantity is equal to or larger than a predetermined value. If the number of detections of the first operating state quantity is smaller than the predetermined value in the predetermined period, the control unit 45 estimates the remaining refrigerant amount in the refrigerant circuit 6 by using the second operating state quantity and each of the estimation models. For example, if the number of detections of the first operating state quantity in the predetermined period, such as one day, is equal to or larger than the predetermined value, such as 50, the control unit 45 estimates the remaining refrigerant amount by using the first operating state quantity and each of the estimation models. Further, if the number of detections of the first operating state quantity in one day is smaller than 50, the control unit 45 estimates the remaining refrigerant amount by using the second operating state quantity and each of the estimation models.

[0032] The control unit 45 estimates, at a predetermined time, such as at one o'clock in the morning, in one day, the remaining refrigerant amount in the refrigerant circuit 6 of a previous day by using the first operating state quantities or the second operating state quantities that are acquired in 24 hours of the previous day. If the number of detections of the first operating state quantity is equal to or larger than the predetermined value, the remaining refrigerant amount is estimated by using the acquired first operating state quantities and the estimation models, and, if the number of detections of the first operating state quantity is smaller than the predetermined value, the remaining refrigerant amount is estimated by using the acquired second operating state quantities and the estimation models. Meanwhile, a specific method of estimating the remaining refrigerant amount in one day will be described later.

[00331 Operation of refrigerant circuit

A flow of the refrigerant in the refrigerant circuit 6

and operation of each of the units when the air conditioner

1 according to the present embodiment performs air

conditioning operation will be described below.

[0034] If the air conditioner 1 performs heating

operation, the four-way valve 12 is switched such that the

first port 12A and the fourth port 12D communicate with

each other and the second port 12B and the third port 12C

communicate with each other (a state indicated by bold

lines in FIG. 2). With this configuration, the refrigerant

circuit 6 enters a heating cycle in which the indoor heat

exchanger 51 functions as the condenser and the outdoor

heat exchanger 13 functions as the evaporator. Meanwhile,

for convenience of explanation, the flow of the refrigerant

at the time of heating operation is indicated by bold

arrows in FIG. 2.

[00351 If the compressor 11 drives while the refrigerant

circuit 6 is in the state as described above, the

refrigerant that is discharged from the compressor 11 flows

through the discharge pipe 21, flows into the four-way

valve 12, flows through the outdoor gas pipe 24 via the

four-way valve 12, and flows into the gas pipe 5. The

refrigerant that has flown through the gas pipe 5 flows into the indoor unit 3 via the gas pipe connection unit 52. The refrigerant that has flown into the indoor unit 3 flows through the indoor gas pipe 56 and flows into the indoor heat exchanger 51. The refrigerant that has flown into the indoor heat exchanger 51 is subjected to heat exchange with indoor air that is taken into the indoor unit 3 by rotation of the indoor unit fan 54, and therefore condenses. In other words, the indoor heat exchanger 51 functions as the condenser and the indoor air that is heated by heat exchange with the refrigerant in the indoor heat exchanger 51 is blown out to the inside of the room via a discharge port (not illustrated), so that the inside of a room in which the indoor unit 3 is installed is heated.

[00361 The refrigerant that has flown from the indoor heat exchanger 51 to the indoor liquid pipe 57 flows out to the liquid pipe 4 via the liquid pipe connection unit 53. The refrigerant that has flown into the liquid pipe 4 flows into the outdoor unit 2. The refrigerant that has flown into the outdoor unit 2 flows through the outdoor liquid pipe 25 and is decompressed by passing through the expansion valve 14. The refrigerant that is decompressed by the expansion valve 14 flows through the outdoor liquid pipe 25, flows into the outdoor heat exchanger 13, is subjected to heat exchange with outdoor air that has flown in from the suction opening (not illustrated) of the outdoor unit 2 by the rotation of the outdoor unit fan 16, and evaporates. The refrigerant that has flown out to the outdoor refrigerant pipe 26 from the outdoor heat exchanger 13 sequentially flows into the four-way valve 12, the outdoor refrigerant pipe 26, the accumulator 15, and the suction pipe 22, is sucked by the compressor 11, is compressed again, and flows out to the outdoor gas pipe 24 via the first port 12A and the fourth port 12D of the four- way valve 12.

[0037] Furthermore, when the air conditioner 1 performs cooling operation, the four-way valve 12 is switched such that the first port 12A and the second port 12B communicate with each other and the third port 12C and the fourth port 12D communicate with each other (a state indicated by dashed lines in FIG. 2). With this configuration, the refrigerant circuit 6 enters a cooling cycle in which the indoor heat exchanger 51 functions as the evaporator and the outdoor heat exchanger 13 functions as the condenser. Meanwhile, for convenience of explanation, the flow of the refrigerant at the time of cooling operation is indicated by dashed-line arrows in FIG. 2.

[0038] If the compressor 11 drives while the refrigerant circuit 6 is in the state as described above, the refrigerant that is discharged from the compressor 11 flows through the discharge pipe 21, flows into the four-way valve 12, flows through the outdoor refrigerant pipe 23 via the four-way valve 12, and flows into the outdoor heat exchanger 13. The refrigerant that has flown into the outdoor heat exchanger 13 is subjected to heat exchange with outdoor air that is taken into the outdoor unit 2 by rotation of the outdoor unit fan 16, and condenses. In other words, the outdoor heat exchanger 13 functions as the condenser, and the outdoor air that is heated by the refrigerant in the outdoor heat exchanger 13 is blown out to the outside of the room from a discharge port (not illustrated).

[0039] The refrigerant that has flown into the outdoor liquid pipe 25 from the outdoor heat exchanger 13 is decompressed by passing through the expansion valve 14. The refrigerant that is decompressed by the expansion valve 14 flows through the liquid pipe 4 and flows into the indoor unit 3. The refrigerant that has flown into the indoor unit 3 flows through the indoor liquid pipe 57, flows into the indoor heat exchanger 51, is subjected to heat exchange with indoor air that has flown in from the suction opening (not illustrated) of the indoor unit 3 by the rotation of the indoor unit fan 54, and evaporates. In other words, the indoor heat exchanger 51 functions as the evaporator, and the indoor air that is cooled by heat exchange with the refrigerant in the indoor heat exchanger

51 is blown out to the inside of the room via a discharge

port (not illustrated), so that the inside of the room in

which the indoor unit 3 is installed is cooled.

[0040] The refrigerant that flows from the indoor heat

exchanger 51 to the gas pipe 5 via the gas pipe connection

unit 52 flows through the outdoor gas pipe 24 of the

outdoor unit 2 and flows into the fourth port 12D of the

four-way valve 12. The refrigerant that has flown into the

fourth port 12D of the four-way valve 12 flows into the

refrigerant inflow side of the accumulator 15 via the third

port 12C. The refrigerant that has flown in from the

refrigerant inflow side of the accumulator 15 flows in via

the suction pipe 22, is sucked by the compressor 11, and is

compressed again.

[0041] While the air conditioner 1 is performing the

cooling operation or the heating operation as described

above, the acquisition unit 42 in the control circuit 18

acquires sensor values of the discharge temperature sensor

31, the outdoor heat exchange outlet sensor 32, and the

outdoor air temperature sensor 33 via the control circuit

17 of the outdoor unit 2. Furthermore, the acquisition

unit 42 acquires sensor values of the indoor heat exchange

intermediate sensor 58 and a suction temperature sensor 59

of the indoor unit 3.

[0042] FIG. 4 is a Mollier diagram illustrating a cooling cycle of the air conditioner 1. As described above, when the air conditioner 1 performs the cooling operation, the outdoor heat exchanger 13 functions as the condenser and the indoor heat exchanger 51 functions as the evaporator, and when the air conditioner 1 performs the heating operation, the outdoor heat exchanger 13 functions as the evaporator and the indoor heat exchanger 51 functions as the condenser.

[0043] The compressor 11 compresses a low-temperature and low-pressure gas refrigerant (a refrigerant in a state at a point A in FIG. 4) that flows in from the evaporator, and discharges a high-temperature and high-pressure gas refrigerant (a refrigerant in a state at a point B in FIG. 4). Meanwhile, temperature of the gas refrigerant that is discharged by the compressor 11 is refrigerant discharge temperature, and the refrigerant discharge temperature is detected by the discharge temperature sensor 31.

[0044] The condenser performs heat exchange between the high-temperature and high-pressure gas refrigerant flown from the compressor 11 and air, and condenses the high temperature and high-pressure gas refrigerant. At this time, in the condenser, the entire gas refrigerant changes to a liquid refrigerant due to a latent heat change, and thereafter, temperature of the liquid refrigerant decreases due to a sensible heat change and the refrigerant enters a super-cooled state (a state at a point C in FIG. 4). Meanwhile, temperature at which the gas refrigerant changes to the liquid refrigerant due to the latent heat change is condensation temperature, and temperature of the refrigerant in the super-cooled state at an outlet of the condenser is heat exchange outlet temperature. The heat exchange outlet temperature among the heat exchanger temperature is detected by the outdoor heat exchange outlet sensor 32 at the time of cooling operation. Meanwhile, at the time of heating operation, the refrigerant flows in an opposite direction of the refrigerant in the cooling operation and the outdoor heat exchanger 13 functions as the evaporator. At the time of heating operation, the outdoor heat exchange outlet sensor 32 is used to detect the temperature of the outdoor heat exchanger 13 and detect freezing or used to control defrosting operation.

[0045] The expansion valve 14 decompresses the low temperature and high-pressure refrigerant that is flown out of the condenser. The refrigerant that is decompressed by the expansion valve 14 becomes a gas-liquid two-phase refrigerant in which gas and liquid are mixed (a refrigerant in a state at a point D in FIG. 4).

[0046] The evaporator performs heat exchange between the gas-liquid two-phase refrigerant that has flown in and air, and evaporates the refrigerant. At this time, in the evaporator, the entire gas-liquid two-phase refrigerant changes to a gas refrigerant due to a latent heat change, and thereafter, temperature of the gas refrigerant increases due to a sensible heat change and the gas refrigerant enters a super-heated state (the state at the point A in FIG. 4) and is sucked by the compressor 11. Meanwhile, temperature at which the liquid refrigerant changes to the gas refrigerant due to the latent heat change is evaporation temperature. The evaporation temperature is indoor heat exchange intermediate temperature that is detected by the indoor heat exchange intermediate sensor 58 at the time of cooling operation. Furthermore, temperature of the refrigerant that is super heated by the evaporator and sucked by the compressor 11 is suction temperature. Meanwhile, at the time of heating operation, the refrigerant flows in an opposite direction of the refrigerant in the cooling operation, and the indoor heat exchanger 51 functions as the condenser. A detection result of the indoor heat exchange intermediate sensor 58 is used to calculate the target discharge temperature.

[0047] Configuration of estimation model

The estimation model is generated by a multiple

regression analysis method that is one of regression

analysis methods by using an arbitrary operating state

quantity (feature value) among a plurality of operating

state quantities. In the multiple regression analysis

method, the estimation model is generated by selecting a

regression equation, in which a P value (a value indicating

a degree of influence of the operating state quantity on

accuracy of the generated estimation model (predetermined

weight parameter)) is minimum and a correction value R2 (a

value indicating accuracy of the generated estimation

model) is maximum in a range from 0.9 to 1.0, from among

regression equations that are obtained from a test result

using an actual air conditioner (hereinafter, an actual

device) (the test result is a result of a test that is

performed by the actual device to examine what value of the

operating state quantity is obtained when the remaining

refrigerant amount in the refrigerant circuit is changed)

or from among regression equations that are obtained from a

plurality of simulation results (results of calculation of

a value of the operating state quantity with respect to the

remaining refrigerant amount, by reproduction of the

refrigerant circuit by numerical calculation). Here, the P

value and the correction value R2 are values related to the

accuracy of the estimation model when the estimation model

is generated by the multiple regression analysis method,

and the accuracy of the generated estimation model increases as the P value decreases and the correction value

R2 approaches 1.0.

[0048] The estimation model includes the cooling

estimation model 62A and the heating estimation model 62B.

In the present embodiment, each of the estimation models is

generated by using a test result that is obtained by using

an actual device as will be described later, and is stored

in the control circuit 18 of the air conditioner 1 in

advance.

[0049] The cooling estimation model 62A is a first

regression equation that is able to estimate the remaining

refrigerant amount at the time of cooling operation with

high accuracy by using the operating state quantity, such

as the first operating state quantity or the second

operating state quantity, at the time of cooling operation.

[0050] First regression equation = (al x rotation speed

of compressor) + (a2 x degree of opening of expansion

valve) + (a3 x discharge temperature of compressor) + (a4 x

heat exchange outlet temperature) + (a5 x outdoor air

temperature) + a6 (1)

[0051] It is assumed that coefficients al to a6 are

determined when the estimation model is generated. The

control unit 45 assigns, at a predetermined time in one

day, each of the rotation speed of the compressor 11, the

degree of opening of the expansion valve 14, the

refrigerant discharge temperature of the compressor 11, the

heat exchange outlet temperature, and the outdoor air

temperature among the first operating state quantities or

the second operating state quantities, which are detected

by the detection unit 43 during 24 hours of the previous

day, to the first regression equation, and calculates the

remaining refrigerant amounts in the refrigerant circuit 6 at time points at which the first operating state quantities or the second operating state quantities are detected. Further, the control unit 45 adopts, as an estimated value of the remaining refrigerant amount of the previous day, one of an average value of the remaining refrigerant amounts calculated by using the first operating state quantities at the respective time points and an average value of the remaining refrigerant amounts calculated using the second operating state quantities at the respective time points. Meanwhile, the reason that each of the rotation speed of the compressor 11, the degree of opening of the expansion valve, the refrigerant discharge temperature of the compressor 11, the outdoor heat exchange outlet temperature, and the outdoor air temperature is assigned is to use the feature value that is used when the cooling estimation model 62A is generated.

The rotation speed of the compressor 11 is detected by, for

example, a rotation speed sensor (not illustrated) of the

compressor 11. As the degree of opening of the expansion

valve, for example, the number of pulses of a pulse signal

that is input from the control unit 45 to a stepping motor

(not illustrated) of the expansion valve is used. The

refrigerant discharge temperature of the compressor 11 is

detected by the discharge temperature sensor 31. The heat

exchange outlet temperature is detected by the outdoor heat

exchange outlet sensor 32. The outdoor air temperature is

detected by the outdoor air temperature sensor 33.

[0052] The heating estimation model 62B is a second

regression equation that is able to estimate the remaining

refrigerant amount at the time of heating operation with

high accuracy by using the operating state quantity, such

as the first operating state quantity or the second

operating state quantity, at the time of heating operation.

[00531 Second regression equation = (all x rotation

speed of compressor) + (a12 x degree of opening of

expansion valve) + (a13 x discharge temperature of

compressor) + (a14 x indoor heat exchange intermediate

temperature) + a15 (2)

[0054] It is assumed that coefficients all to a15 are

determined when the estimation model is generated. The

control unit 45 assigns, at a predetermined time in one

day, each of the rotation speed of the compressor 11, the

degree of opening of the expansion valve 14, the

refrigerant discharge temperature of the compressor 11, and

the indoor heat exchange intermediate temperature among the

first operating state quantities or the second operating

state quantities, which are detected by the detection unit

43 during 24 hours of the previous day, to the second

regression equation, and calculates the remaining

refrigerant amounts in the refrigerant circuit 6 at time

points at which the first operating state quantities or the

second operating state quantities are detected. Further,

the control unit 45 adopts, as an estimated value of the

remaining refrigerant amount of the previous day, one of an

average value of the remaining refrigerant amounts

calculated by using the first operating state quantities at

the respective time points and an average value of the

remaining refrigerant amounts calculated using the second

operating state quantities at the respective time points.

Meanwhile, the reason that each of the rotation speed of

the compressor 11, the degree of opening of the expansion

valve, the refrigerant discharge temperature of the

compressor 11, and the indoor heat exchange intermediate

temperature is assigned is to use the feature value that is

used when the heating estimation model 62B is generated.

The rotation speed of the compressor 11 is detected by the

rotation speed sensor (not illustrated) of the compressor

11. As the degree of opening of the expansion valve, for

example, the number of pulses of a pulse signal that is

input from the control unit 45 to a stepping motor (not

illustrated) of the expansion valve is used. The

refrigerant discharge temperature of the compressor 11 is

detected by the discharge temperature sensor 31. The

indoor heat exchange intermediate temperature among the

heat exchanger temperature is detected by the indoor heat

exchange intermediate sensor 58.

[00551 As described above, the remaining refrigerant

amount is estimated by using the first regression equation

at the time of cooling operation. Further, the remaining

refrigerant amount is estimated by using the second

regression equation at the time of heating operation.

[00561 Method of generating regression equations

The feature value that is used to generate the first

regression equation and the second regression equation will

be described below. At the time of cooling operation in

which the first regression equation is used, in the present

embodiment, each of the operating state quantities, such as

the rotation speed of the compressor 11, the degree of

opening of the expansion valve 14, the refrigerant

discharge temperature of the compressor 11, the outdoor

heat exchange outlet temperature, and the outdoor air

temperature, is used as the feature value that is used when

the first regression equation is generated by the multiple

regression analysis method. Further, a test result using

an actual device is used as each of the operating state

quantities. Furthermore, at the time of heating operation

in which the second regression equation is used, in the

present embodiment, each of the operating state quantities, such as the rotation speed of the compressor 11, the degree of opening of the expansion valve 14, the refrigerant discharge temperature of the compressor 11, and the indoor heat exchange intermediate temperature, is used as the feature value that is used when the second regression equation is generated by the multiple regression analysis.

Moreover, a test result using an actual device is used as

each of the operating state quantities. Meanwhile, when

the first regression equation that is the cooling

estimation model 62A or the second regression equation that

is the heating estimation model 62B as described above is

generated, the first operating state quantity that is

detected when the first stability condition is met is used.

[0057] Specifically, at a design stage of the air

conditioner 1, as one example, the air conditioner 1 is

subjected to test drive by changing outdoor air

temperature, indoor temperature, and a refrigerant storage

amount while the indoor unit 3 is operating, and a

relationship between the feature value and a refrigerant

shortage rate is acquired. As a condition under which the

test drive is performed, for example, the outdoor air

temperature is changed to 200C, 250C, 300C, 350C, and 400C.

Meanwhile, when the test drive is performed, it may be

possible to add a different parameter of the outdoor air

temperature.

[0058] Among the plurality of operating state

quantities, an arbitrary operating state quantity (feature

value) that is used for the estimation model is obtained

from a test result (hereinafter, referred to as teacher

data) that indicates a relationship between the plurality

of operating state quantities and the refrigerant storage

amount. Specifically, the teacher data is data (teacher

data that is used to generate the estimation model by the multiple regression analysis method) in which the remaining refrigerant amount, which is changed by changing a refrigerant amount stored in the refrigerant circuit, and each of the operating state quantities that are obtained when the operation is performed with the changed remaining refrigerant amount are associated with each other.

[00591 In the multiple regression analysis method, for

example, the test drive is performed while changing the

refrigerant storage amount, each of the operating state

quantities that vary for each outside air temperature with

respect to each refrigerant storage amount, and data

classification is performed for each refrigerant storage

amount. Examples of the operating state quantity that is

used as the teacher data include the operating state

quantities of the compressor 11, the indoor unit 3, and the

outdoor unit 2. Examples of the operating state quantity

of the compressor 11 include the rotation speed, a target

rotation speed, an operating time, the refrigerant

discharge temperature, the target discharge temperature,

and output voltage. Furthermore, examples of the operating

state quantity of the indoor unit 3 include a rotation

speed and a target rotation speed of the indoor unit fan

54, and the heat exchanger intermediate sensor temperature.

Moreover, examples of the operating state quantity of the

outdoor unit 2 include a rotation speed and a target

rotation speed of the outdoor unit fan 16, the degree of

opening of the expansion valve 14, and sensor temperature

at the outlet of the condenser. Furthermore, by performing

machine learning by using the data for each refrigerant

storage amount as the teacher data, an arbitrary operating

state quantity (feature value) for estimating the remaining

refrigerant amount is extracted, coefficients are derived,

and the estimation model is generated.

[00601 Operation of process of acquiring operating state

quantity

Operation at the time of acquiring the operating state

quantity by the air conditioner 1 of the first embodiment

will be described below. FIG. 5 is a flowchart

illustrating an example of the processing operation

performed by the control circuit 18 in relation to

acquisition of the operating state quantity. In FIG. 5,

the acquisition unit 42 of the control circuit 18

determines whether a predetermined timing for acquiring the

operating state quantity has come (Step Sl). Meanwhile,

the predetermined timing is a timing that comes in five

minute intervals for acquiring the operating state

quantity, for example. If the predetermined timing has

come (Step Sl: Yes), the acquisition unit 42 acquires the

operating state quantity of the air conditioner 1 (Step

S12). After acquiring the operating state quantity of the

air conditioner 1, the acquisition unit 42 stores the

operating state quantity in the operating state quantity

memory 61 (Step S13), and returns the process to Step Sl.

Meanwhile, if the predetermined timing has not come at Step

Sl (Step Sl: No), the acquisition unit 42 returns the

process to Step Sl.

[0061] Operation of process of detecting operating state

quantity

FIG. 6 is a flowchart illustrating an example of the

processing operation performed by the control circuit 18 in

relation to detection the operating state quantity. In

FIG. 6, the detection unit 43 of the control circuit 18

refers to, at a predetermined time (for example, at one

o'clock in the morning as described above) in one day, the

operating state quantities that are stored in the operating

state quantity memory 61, and determines whether an operating state quantity that is acquired after a lapse of eight minutes since activation of the compressor 11 is present in the operating state quantity memory 61 (Step

S21). If the operating state quantity that is acquired

after a lapse of eight minutes since activation of the

compressor 11 is present (Step S21: Yes), the detection

unit 43 determines whether an operating state quantity that

is acquired when a certain state, in which variation of the

rotation speed of the compressor 11 falls within a second

predetermined range, such as ±5 rps, continues for a second

predetermined period, such as 12 minutes, or more, that is,

when the second stability condition is met, is present in

the operating state quantity memory 61 (Step S22).

Meanwhile, timestamps that indicate acquisition times are

added to the operating state quantities that are acquired

at timings in five-minute intervals and that are stored in

the operating state quantity memory 61, and the detection

unit 43 is able to determine whether an operating state

quantity that is acquired in a time period in which the

second stability condition is met is present by referring

to the timestamps that are added to the operating state

quantities.

[0062] If the operating state quantity that is acquired

when the certain state, in which the variation of the

rotation speed of the compressor 11 falls within the second

predetermined range, continues for the second predetermined

period or more is not present in the operating state

quantity memory 61 (Step S22: No), the detection unit 43

determines whether an operating state quantity that is

acquired when a certain state, in which the variation of

the rotation speed of the compressor 11 falls within the

first predetermined range, such as ±1 rps, continues for

the first predetermined period, such as 5 minutes, or more, is present in the operating state quantity memory 61 (Step

S23). If the operating state quantity that is acquired

when the certain state, in which the variation of the

rotation speed of the compressor 11 falls within the first

predetermined range, continues for the first predetermined

period or more is present in the operating state quantity

memory 61 (Step S23: Yes), the detection unit 43 determines

whether an operating state quantity that is acquired when a

certain state, in which an absolute value of a difference

between the refrigerant discharge temperature and the

target discharge temperature of the compressor 11 is equal

to or smaller than a predetermined value, such as 20C,

continues for the first predetermined period or more is

present among the operating state quantities that meet the

condition at Step S23 (Step S24). In other words, the

detection unit 43 performs the determination at Step S23

and the determination at Step S24, and determines whether

the operating state quantity that is acquired when the

first stability condition is met is present in the

operating state quantity memory 61. Meanwhile, the

detection unit 43 is able to determine whether the

operating state quantity that is acquired in a time period

in which the first stability condition is met is present by

referring to the timestamps that are added to the operating

state quantities.

[00631 If the operating state quantity that is acquired

when the certain state, in which the absolute value between

the refrigerant discharge temperature and the target

discharge temperature of the compressor 11 is equal to or

smaller than the predetermined value, continues for the

first predetermined period or more is present among the

operating state quantities that meet the condition at Step

S23 (Step S24: Yes), the detection unit 43 detects the corresponding operating state quantity as the first operating state quantity (Step S25). Further, the detection unit 43 stores the first operating state quantity that is detected at Step S25 in the first operating state quantity memory 61A (Step S26), and returns the process to Step S21.

[0064] Furthermore, if the operating state quantity that is acquired when the certain state, in which the variation of the rotation speed of the compressor 11 falls within the second predetermined range, continues for the second predetermined period or more is present in the operating state quantity memory 61 (Step S22: Yes), the detection unit 43 detects the corresponding operating state quantity as the second operating state quantity (Step S27). The detection unit 43 stores the second operating state quantity that is detected at Step S27 in the second operating state quantity memory 61B (Step S28), and the process goes to Step S23.

[0065] Moreover, if the operating state quantity that is acquired after a lapse of eight minutes since activation of the compressor 11 is not present in the operating state quantity memory 61 (Step S21: No), the detection unit 43 returns the process to Step S21. Furthermore, if the operating state quantity that is acquired when the certain state, in which the variation of the rotation speed of the compressor 11 falls within the first predetermined range, continues for the first predetermined period or more is not present in the operating state quantity memory 61 (Step S23: No), the detection unit 43 returns the process to Step S21. Moreover, if the operating state quantity that is acquired when the certain state, in which the absolute value of the difference between the refrigerant discharge temperature and the target discharge temperature of the compressor 11 is equal to or smaller than the predetermined value, continues for the first predetermined period or more is not present among the operating state quantities that meet the condition at Step S23 (Step S24: No), the detection unit 43 returns the process to Step S21.

[00661 Operation of process of estimating remaining refrigerant amount FIG. 7 is a flowchart illustrating an example of processing operation performed by the control circuit 18 in relation to estimation of the remaining refrigerant amount. In FIG. 7, the control unit 45 of the control circuit 18 determines whether the estimation timing has come (Step S31). Meanwhile, the estimation timing is the predetermined time in one day, such as at one o'clock in the morning, for example. If the estimation timing has come (Step S31: Yes), the control unit 45 counts the number of the first operating state quantities (the number of detections) acquired in a predetermined period, such as a previous day (Step S32), and determines whether the number of detections of the first operating state quantity in the predetermined period is equal to or larger than a predetermined number, for example, 50 (Step S33).

[0067] If the number of detections of the first operating state quantity in the predetermined period is equal to or larger than the predetermined value (Step S33: Yes), the control unit 45 calculates a remaining refrigerant amount in the refrigerant circuit 6 for each of the acquired first operating state quantities by using the first operating state quantities and each of the estimation models (Step S34). For example, the control unit 45 at the time of cooling operation calculates the remaining refrigerant amount in the refrigerant circuit 6 for each of the acquired first operating state quantities by using the first operating state quantities and the cooling estimation model 62A. Furthermore, the control unit 45 at the time of heating operation calculates the remaining refrigerant amount in the refrigerant circuit 6 for each of the acquired first operating state quantities by using the first operating state quantity and the heating estimation model 62B.

[00681 If the number of detections of the first

operating state quantity in the predetermined period is not

equal to or larger than the predetermined value (Step S33:

No), that is, if the number of detections is smaller than

the predetermined value, the control unit 45 calculates the

remaining refrigerant amount in the refrigerant circuit 6

for each of the acquired second operating state quantities

by using the second operating state quantities and the

estimation model (Step S35). For example, the control unit

45 at the time of cooling operation calculates the

remaining refrigerant amount in the refrigerant circuit 6

for each of the second operating state quantities by using

the acquired second operating state quantities and the

cooling estimation model 62A. Furthermore, the control

unit 45 at the time of heating operation calculates the

remaining refrigerant amount in the refrigerant circuit 6

for each of the acquired second operating state quantities

by using the second operating state quantities and the

heating estimation model 62B.

[00691 Subsequently, the control unit 45 calculates an

average value of the remaining refrigerant amounts that are

calculated at Step S34 or the remaining refrigerant amounts

that are calculated at Step S35 (Step S36), and determines

whether the calculated average value of the remaining

refrigerant amounts is smaller than a predetermined value

(Step S37). Here, a predetermined value is a value for which it is determined, by a test or the like that is performed in advance, that air conditioning performance of the air conditioner 1 is affected if the remaining refrigerant amount in the refrigerant circuit 6 becomes smaller than the predetermined value, and is, for example, 60% of a refrigerant amount that is stored in the refrigerant circuit 6 when the air conditioner 1 is installed.

[0070] If the calculated average value of the remaining refrigerant amounts is smaller than the predetermined value (Step S37: Yes), the control unit 45 outputs the calculated average value as an estimated value of the remaining refrigerant amount (Step S38), and returns the process to Step S31. Here, output of the estimated value of the remaining refrigerant amount is transmission of the estimated value of the remaining refrigerant amount to, for example, a remote controller (not illustrated) for operating the indoor unit 3 or a mobile terminal of a user of the air conditioner 1, and the received estimated value of the remaining refrigerant amount is displayed on a display unit of each of the remote controller and the mobile terminal that have received the estimated value of the remaining refrigerant amount.

[0071] Meanwhile, if the estimation timing has not come at Step S31 (Step S31: No), the control unit 45 returns the process to Step S31. Further, if the average value of the remaining refrigerant amounts calculated at Step S37 is not smaller than the predetermined value (Step S37: No), the control unit 45 returns the process to Step S31.

[0072] Effects of first embodiment In the air conditioner 1 of the first embodiment, the refrigerant circuit 6 estimates the remaining refrigerant amount in the refrigerant circuit 6 by using the first operating state quantity that indicates an operating state at the time of air conditioning operation while the first stability condition is met and each of the estimation models for cooling operation and heating operation. With use of the first operating state quantity for estimation of the remaining refrigerant amount, it is possible to accurately estimate the remaining refrigerant amount because the first operating state quantity is also used to generate each of the estimation models. Further, if the first stability condition is not met, that is, if it is difficult to achieve a state in which the refrigerant circuit 6 is stable, the refrigerant circuit 6 estimates the remaining refrigerant amount in the refrigerant circuit

6 by using the second operating state quantity that

indicates an operating state at the time of air

conditioning operation while the second stability condition

is met and each of the estimation models for cooling

operation and heating operation. With use of the second

operating state quantity for estimation of the remaining

refrigerant amount, although accuracy of each estimation is

reduced as compared to a case in which the first operating

state quantity is used, it is possible to ensure certain

estimation accuracy of the remaining refrigerant amount by

obtaining an average of estimation results and adopting the

average value as the estimated value of the remaining

refrigerant amounts because a large amount of the second

operating state quantity can be obtained as compared to the

first operating state quantity.

[0073] If the number of detections of the first

operating state quantity in the predetermined period is

equal to or larger than the predetermined value, the

control unit 45 estimates the remaining refrigerant amount

by using the first operating state quantity and the estimation models. If the number of detections of the first operating state quantity in the predetermined period is smaller than the predetermined value, the remaining refrigerant amount is estimated by using the second operating state quantity and the estimation model. As a result, when the remaining refrigerant amount is estimated, it is possible to properly use the first operating state quantity or the second operating state quantity.

[0074] If the control unit 45 estimates the remaining refrigerant amount by using the second operating state quantity and the estimation model at each predetermined timing, the control unit 45 outputs an average value of the remaining refrigerant amounts that are estimated at predetermined timings in the predetermined period, as the remaining refrigerant amount in the predetermined period. As a result, it is possible to estimate the remaining refrigerant amount with high accuracy.

[0075] Meanwhile, in the first embodiment, it is assumed that the first stable condition is met when the certain state, in which the variation of the rotation speed of the compressor 11 falls within the first predetermined range and the absolute value of the difference between the refrigerant discharge temperature and the target discharge temperature of the compressor 11 is equal to or smaller than a predetermined value, continues for the first predetermined period or more. However, it may be possible to assume that the first stable condition is met only when a certain state, in which the variation of the rotation speed of the compressor 11 falls within the first predetermined range, continues for the first predetermined period or more, and an appropriate change is applicable.

[0076] In the first embodiment, it is assumed that the second stable condition is met when the certain state, in which the variation of the rotation speed of the compressor 11 falls within the second predetermined range that exceeds the first predetermined range, continues for the second predetermined period, which exceeds the first predetermined period, or more. However, it may be possible to assume that the second stable condition is met when a certain state, in which the variation of the rotation speed of the compressor 11 falls within the second predetermined range, continues for the first predetermined period or more, even if the certain state does not continue for the second predetermined period or more, and an appropriate change is applicable.

[0077] In the first embodiment, the case has been described in which the remaining refrigerant amount is estimated at each predetermined timing, but estimation need not always be performed regularly, and an appropriate change is applicable.

[0078] In the first embodiment, the case has been described in which each of the operating state quantities is obtained by test drive of the air conditioner 1 at the design stage of the air conditioner 1, and the estimation model that is obtained by causing a terminal, such as a server, with a learning function to perform learning of the test result is stored in the control circuit 18 in advance. Alternatively, it may be possible to acquire each of the operating state quantities by a simulation, and store an estimation model that is obtained by performing learning on an acquired result in advance. Furthermore, it may be possible to provide a server 120 that is connected to the air conditioner 1 by a communication network 110, and the server 120 may generate the first regression equation and the second regression equation and transmit the first regression equation and the second regression equation to the air conditioner 1. This embodiment will be described below.

[0079] Second Embodiment

Configuration of air conditioning system

FIG. 8 is an explanatory diagram illustrating an air

conditioning system 100 of a second embodiment. Meanwhile,

the same components as those of the air conditioner 1 of

the first embodiment are denoted by the same reference

symbols, and explanation of the same configurations and the

same operation will be omitted. The air conditioning

system 100 illustrated in FIG. 8 includes the air

conditioner 1 described in the first embodiment, the

communication network 110, and the server 120, and the air

conditioner 1 is communicably connected to the server 120

via the communication network 110.

[0080] The server 120 includes a generation unit 121 and

a transmission unit 122. The generation unit 121 generates

an estimation model by a multiple regression analysis

method using the operating state quantity that is related

to estimation of the remaining refrigerant amount of a

refrigerant that is stored in the refrigerant circuit 6.

Meanwhile, the estimation model includes, for example, the

cooling estimation model 62A and the heating estimation

model 62B that are described in the first embodiment. The

transmission unit 122 transmits each of the estimation

models that are generated by the generation unit 121 to the

air conditioner 1 via the communication network 110. The

control circuit 18 of the air conditioner 1 calculates the

remaining refrigerant amount in the refrigerant circuit 6

in the air conditioner 1 by using each of the received

estimation models.

[0081] The generation unit 121 in the server 120

regularly collects operating state quantities at the time of cooling operation from a standard device (installed in a test room of a manufacturing company or the like) of the air conditioner 1 capable of measuring the remaining refrigerant amount in the refrigerant circuit 6, and generates or updates the cooling estimation model 62A by using a comparison result between the remaining refrigerant amount that is estimated by each of the estimation models and the measured remaining refrigerant amount and by using the collected operating state quantities. Further, the transmission unit 122 in the server 120 regularly transmits the generated or updated cooling estimation model 62A to the air conditioner 1. Meanwhile, as in the first embodiment, it may be possible to obtain, by a simulation, the operating state quantity that is used to generate each of the estimation models, and cause the generation unit 121 to generate each of the estimation models by using the operating state quantity that is obtained by the simulation.

[0082] The generation unit 121 in the server 120 regularly collects operating state quantities at the time of heating operation from the standard device of the air conditioner 1 as described above, and generates the heating estimation model 62B by using a comparison result between the remaining refrigerant amount that is estimated by the estimation model and the measured remaining refrigerant amount and by using the collected operating state quantities. Further, the transmission unit 122 in the server 120 regularly transmits the generated heating estimation model 62B to the air conditioner 1. Meanwhile, as in the first embodiment, it may be possible to obtain, by a simulation, the operating state quantity that is used to generate each of the estimation models, and cause the generation unit 121 to generate each of the estimation models by using the operating state quantity that is obtained by the simulation.

[00831 Effects of second embodiment The server 120 of the second embodiment generates the estimation model for estimating the remaining refrigerant amount by using the multiple regression analysis method using the operating state quantity related to estimation of the remaining refrigerant amount in the refrigerant circuit 6, and transmits the generated estimation model to the air conditioner 1. The air conditioner 1 estimates the remaining refrigerant amount by using the estimation model that is received from the server 120 and the current operating state quantity. As a result, even for the home use air conditioner 1, it is possible to estimate the remaining refrigerant amount at a current time by using highly accurate estimation model.

[0084] Furthermore, in the present embodiment, the case has been described in which the remaining refrigerant amount in the refrigerant circuit 6 is estimated. However, the present invention is not limited to this example, and in particular, it may be possible to estimate a refrigerant shortage rate that is a ratio of the amount of the refrigerant that has leaked to the outside from the refrigerant circuit 6 to a storage amount (initial value) that is obtained when the refrigerant circuit 6 is filled with the refrigerant. Moreover, it may be possible to multiply the estimated refrigerant shortage rate by the initial value, and provide the amount of the refrigerant that has leaked from the refrigerant circuit 6 to the outside. Furthermore, it may be possible to generate an estimation model that estimates an absolute amount of the refrigerant that has leaked from the refrigerant circuit 6 to the outside or an absolute amount of the refrigerant that remains in the refrigerant circuit 6, and provide an estimation result obtained by the estimation model. When the estimation model that estimates the absolute amount of the refrigerant that has leaked from the refrigerant circuit 6 to the outside or the absolute amount of the refrigerant that remains in the refrigerant circuit 6 is to be generated, it is sufficient to take into account capacities of the outdoor heat exchanger 13 and the indoor heat exchanger 51 or a capacity of the liquid pipe 4, in addition to each operating state quantity as described above.

[00851 Moreover, if it is assumed that 100% indicates

that a defined amount of refrigerant is stored, the

refrigerant shortage rate is a ratio of a decrease amount

with respect to the defined amount. Alternatively, it may

be possible to estimate the refrigerant shortage rate

immediately after the defined amount of refrigerant is

stored in the refrigerant circuit 6, and adopt an

estimation result as 100%. For example, if the refrigerant

shortage rate that is estimated immediately after the

defined amount of refrigerant is stored in the refrigerant

circuit 6 is 90%, that is, if it is estimated that the

amount of the refrigerant stored in the refrigerant circuit

6 is smaller than the defined amount by 10%, it may be

possible to adopt the refrigerant amount that is smaller

than the defined amount by 10% as 100%. In this manner, by

adjusting the refrigerant amount that is adopted as 100% to

the estimation result, it is possible to more accurately

estimate ae subsequent refrigerant shortage rate.

[00861 Modification

In the present embodiment, the case has been described

in which the control circuit 18 included in the indoor unit

3 controls the entire air conditioner 1, but the control circuit 18 may be provided in the outdoor unit 2 or a cloud side. In the present embodiment, the case has been described in which the estimation model is generated by the server 120, but the estimation model may be calculated by a human being, instead of the server 120, from a simulation result. Furthermore, in the present embodiment, the case has been described in which the control circuit 18 of the indoor unit 3 estimates the refrigerant amount by using the estimation model, but the server 120 that generates the estimation model may estimate the refrigerant amount.

Moreover, in the present embodiment, the case has been

described in which each of the estimation models is

generated by using the multiple regression analysis method,

but the estimation models may be generated by using a

support vector regression (SVR), a neural network (NN), or

the like that is a machine learning method capable of

performing a general regression analysis method. In this

case, to select a feature value, it is sufficient to use a

general method (forward feature selection method, backward

feature elimination, or the like) for selecting the feature

value such that accuracy of the estimation models is

improved, instead of the P value and the correction value

R2 that are used in the multiple regression analysis

method.

[0087] Moreover, the components of the units illustrated

in the drawings are conceptual function, and need not

always be physically configured in the manner illustrated

in the drawings. In other words, specific forms of

distribution and integration of the units are not limited

to those illustrated in the drawings, and all or part of

the units may be functionally or physically distributed or

integrated in arbitrary units depending on various loads or

use conditions.

[00881 Further, all or an arbitrary part of the

processing functions implemented by the apparatuses may be

realized by a central processing unit (CPU) (or a

microcomputer, such as a micro processing unit (MPU) or a

micro controller unit (MCU)). Furthermore, all or an

arbitrary part of the processing functions may be may be

implemented by a program that is executed by a CPU (or a

microcomputer, such as an MPU or an MCU) or hardware using

wired logic.

Reference Signs List

[00891 1 air conditioner

2 outdoor unit

3 indoor unit

11 compressor

18 control circuit

42 acquisition unit

43 detection unit

44 storage unit

45 control unit

61A first operating state quantity memory

61B second operating state quantity memory

62A cooling estimation model

62B heating estimation model

Claims (7)

1. An air conditioner that includes a refrigerant circuit

that is formed by connecting, by a refrigerant pipe, an

indoor unit including an indoor heat exchanger to an

outdoor unit including a compressor, an outdoor heat

exchanger, and an expansion valve, the refrigerant circuit

being filled with a predetermined amount of a refrigerant,

the air conditioner comprising:

an acquisition unit that regularly acquires an

operating state quantity at a time of air conditioning

operation;

a storage unit that stores therein the operating state

quantity that is acquired by the acquisition unit;

an estimation model that estimates a refrigerant

remaining amount in the refrigerant circuit by using the

operating state quantity;

a detection unit that detects, from the storage unit,

one of a first operating state quantity and a second

operating state quantity, the first operating state

quantity being an operating state quantity in a state in

which the refrigerant circuit meets a first stability

condition, the second operating state quantity being an

operating state quantity in a state in which the

refrigerant circuit meets a second stability condition that

is different from the first stability condition; and

a control unit that estimates the remaining

refrigerant amount in the refrigerant circuit by using the

estimation model and the operating state quantity that is

detected by the detection unit.

2. The air conditioner according to claim 1, wherein the

second stability condition is a mild condition as compared

to the first stability condition.

3. The air conditioner according to claim 1 or 2, wherein

the control unit

estimates the remaining refrigerant amount by using

the first operating state quantity and the estimation model

if number of detections of the first operating state

quantity detected by the detection unit in a predetermined

period is equal to or larger than a predetermined value,

and

estimates the remaining refrigerant amount by using

the second operating state quantity and the estimation

model if the number of detections of the first operating

state quantity detected by the detection unit in the

predetermined period is smaller than the predetermined

value.

4. The air conditioner according to claim 1 or 2, wherein

the detection unit

adopts, as the first operating state quantity, the

operating state quantity that is detected in a state in

which the first stability condition is met, the state being

a state in which variation of a rotation speed of the

compressor falls within a first predetermined range for a

first predetermined period or more, and

adopts, as the second operating state quantity, the

operating state quantity that is detected in a state in

which the second stability condition is met, the state

being a state in which the variation of the rotation speed

of the compressor falls within a second predetermined range

that exceeds the first predetermined range for the first

predetermined period or more or for a second predetermined

period or more, the second predetermined period exceeding

the first predetermined period.

5. The air conditioner according to claim 4, wherein the

detection unit adopts, as the first operating state

quantity, the operating state quantity that is detected in

a state in which the first stability condition is met, the

state being a state in which an absolute value of a

difference between refrigerant discharge temperature and

target discharge temperature of the compressor is equal to

or smaller than a predetermined value for the first

predetermined period or more, in addition to when the first

condition is met.

6. The air conditioner according to claim 1 or 2, wherein

the detection unit detects the first operating state

quantity and the second operating state quantity.

7. The air conditioner according to claim 1 or 2, wherein

if the control unit estimates the remaining refrigerant

amount by using the second operating state quantity and the

estimation model at each predetermined timing, the control

unit outputs, as the remaining refrigerant amount in the

predetermined period, an average value of the remaining

refrigerant amounts that are estimated at the respective

predetermined timings in the predetermined period.