JP3028008B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an air conditioner having a compressor whose operating frequency is variably adjusted by an inverter, and more particularly to a measure for correcting an error due to a length of a communication pipe.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 63-6350
As disclosed in Japanese Patent Application Laid-Open Publication No. H07-175, in the air conditioner, the outdoor unit detects the saturation temperature corresponding to the suction pressure, controls the operating capacity of the compressor according to the detected value, and controls the operation between the outdoor unit and the indoor unit. In order to cope with the deviation of the saturation temperature equivalent to the suction pressure due to the pressure loss from the actual saturation temperature equivalent to the evaporating pressure, the correction coefficient is manually switched according to the length of the connecting pipe to control the saturation temperature equivalent to the suction pressure. It is a known technique that corrects the value in accordance with the inverter frequency to perform accurate capacity control by transmitting and receiving signals only from the outdoor unit.

Further, as disclosed in Japanese Patent Application Laid-Open No. 2-195155, the relationship between the inverter frequency and the pressure loss in the connecting pipe is stored in advance as a plurality of relational expressions using the connecting pipe length as a parameter, and is fixed. While operating at the inverter frequency, the pressure loss at that time is detected as the difference between the evaporating pressure equivalent saturation temperature and the suction pressure equivalent saturation temperature, and the relational formula between the inverter frequency and the pressure loss at that time is determined. As a known technique, a relational expression corresponding to the communication pipe length of the apparatus, that is, a correction coefficient is determined, and the control target value of the capacity control is corrected using the correction coefficient.

[0004]

By the way, the control of the capacity of the compressor, that is, the control of the inverter frequency, is basically performed by controlling the saturation temperature corresponding to the evaporating pressure of the refrigerant at a constant value, thereby obtaining an appropriate refrigerant circulation amount according to the air conditioning load. Therefore, the temperature should be controlled using the saturation temperature corresponding to the evaporation pressure in the evaporator as an index. That is, since there is a pressure loss in the communication pipe between the indoor unit and the outdoor unit, the saturation temperature corresponding to the suction pressure of the refrigerant detected in the outdoor unit does not match the actual saturation temperature corresponding to the evaporation pressure in the indoor unit .

[0005] However, it is preferable to control the capacity of the compressor using the signal detected by the sensor of the outdoor unit, rather than using the signal detected by the sensor of the indoor unit. There is an advantage that the signal from the sensor is unified .

[0006] Among the above-mentioned conventional ones, the former publication discloses, from this viewpoint, the control target value of the saturation temperature corresponding to the suction pressure is changed to a value corresponding to the actual saturation temperature corresponding to the evaporation pressure in accordance with the length of the connecting pipe. The correction is used to control the inverter frequency using the accurate control target value as an index.In this case, when installing the device, manually switch the correction coefficient for correcting the pressure loss according to the pipe length. Therefore, there is a possibility that an error in the switching or forgetting of the switching may occur.

On the other hand, in the case of the latter publication, a correction coefficient for correcting pressure loss is automatically calculated according to the length of the connecting pipe in order to cope with such a setting error. And the correction coefficient is used to correct the control target value during the cooling operation.

The factors that change the pressure loss in the communication pipe between the outdoor unit and the indoor unit include the pipe length, the amount of circulating refrigerant, and the specific volume of the refrigerant. That is, when the refrigerant is in a dry state, the specific volume is larger than when the refrigerant is in a moderately wet state, so that the pressure loss differs even if the communication pipe length and the operating capacity of the compressor are the same. Therefore, if the correction coefficient is determined under the refrigerant condition different from the condition in which the relational expression set in advance is determined, the control target value of the frequency control will be corrected according to the incorrect correction coefficient, and the accurate There is a possibility that the power cannot be controlled to an appropriate level.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to perform a set operation for determining a correction coefficient for correcting a control target value of a performance control under an appropriate condition. The target value of the control is accurately determined,
The purpose is to improve control performance and reliability.

[0010]

In order to achieve the above object, the means of the first aspect of the present invention is to provide a compressor (1) whose operating capacity is variably adjusted as shown in FIG. The outdoor unit (A) having the heat exchanger (6) and the indoor unit (B) having the use side heat exchanger (12) and the use side electric expansion valve (13) are connected to the liquid side communication pipe (11a) and the gas. A suction pressure detecting means (P2) for detecting the saturation temperature corresponding to the suction pressure of the refrigerant in the outdoor unit (A), which is connected by the side communication pipe (11b), and which operates during the cooling operation of the air conditioner. The present invention is directed to an air conditioner in which the operation capacity of the compressor (1) is controlled according to the suction pressure equivalent saturation temperature detected by the detection means (P2).

[0011] And, the evaporation pressure detecting means for detecting the evaporation pressure corresponding saturation temperature of the refrigerant in the upper Symbol utilization-side heat exchanger (12) (Th2), the operating capacity of the compressor (1) and the gas side communication pipe the relationship between the pressure loss of the refrigerant in said gas-side communication pipe and a storage means for storing a length of (11b) as a plurality of relational expressions as parameters (51), cooling Sai
And the use-side electric expansion valve (13)
Constant large opening and constant operating capacity of compressor (1)
A set operation control means (53) for controlling the oil return operation state to a large capacity, and a superheat degree detection means (6) for detecting the degree of superheat of the suction refrigerant during operation by the set operation control means (53).
And 0), in luck rolling that by the above-mentioned setting operation control means (53),
When the suction superheat degree detected by the superheat degree detection means (60) is smaller than a predetermined value, the suction pressure detection means (P
2) From the relationship between the difference between the evaporating pressure equivalent saturation temperature and the suction pressure equivalent saturation temperature detected by the evaporating pressure detecting means (Th2) and the operating capacity of the compressor (1), the storage means (51)
Correction coefficient determination means for determining a correction factor a relational expression corresponding to a plurality of relational expressions sac Chi communicating絡配pipe length to be stored in (5
4).

As shown by the broken line in FIG. 1, the means adopted by the second aspect of the present invention is that, in the first aspect of the present invention, the operating capacity of the compressor (1) is reduced during the cooling operation of the air conditioner. Correction means (55) for correcting the control target value of the capacity control means (50) using the product of the correction coefficient corrected by the correction coefficient determination means (54) and the operating capacity of the compressor (1) according to the change. ).

[0013]

According to the first aspect of the present invention, the set operation control means (5
When the operation for keeping the operating capacity of the compressor (1) constant is performed by 3), the operating capacity of the compressor (1) previously stored in the storage means (51) is compared with the operating capacity of the compressor (1) by the correction coefficient determining means (54). From the relational expression with the pressure loss, the relational expression corresponding to the communication pipe length of the air conditioner is determined as a correction coefficient.
In this case, if the refrigerant state is not a proper wet state but a dry state, even if the operating capacity of the compressor (1) is the same, the pressure loss differs from the proper state due to an increase in the specific volume, and an erroneous correction coefficient is increased. Although the correction coefficient may be determined, in the present invention, the correction coefficient is determined under an appropriate wet condition in which the degree of superheat detected by the degree of superheat detection means (60) is smaller than a predetermined value. The coefficients will be determined.

Further, since the setting operation is performed by the setting operation section (53) is an oil return operation, the refrigerant has become a proper wet state, the relational expression because the operating capacity is also large in the compressor (1) The accuracy of the determination is good. Further, since the existing oil return operation mode is used without separately providing the set operation mode for determining the correction coefficient in the air conditioner, the control configuration is simplified.

According to the second aspect of the present invention, the correction coefficient is determined by the correction coefficient determining means in accordance with a change in the operating capacity of the compressor during the cooling operation of the air conditioner. Since the control target value of the capacity control is corrected using the product of the correction coefficient and the operating capacity of the compressor (1), the control function of the capacity control is improved.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

FIG. 2 shows a refrigerant piping system of the outdoor unit (A) of the air conditioner according to the embodiment. Inside the outdoor unit (A), the output frequency is variable in the range of 30 to 70 Hz every 10 Hz. Inverter (2a) switched to
The capacity is adjusted to full load (100%) and unload (50%) by the first compressor (1a) whose capacity is adjusted by the first compressor (1a) and the unloader (2b) that differentials depending on the pilot pressure.
A variable capacity compressor (1) configured by connecting a second compressor (1b) adjusted to two stages of states in parallel via a check valve (1e); Compressor (1a, 1
an oil separator (4) for separating the oil in the gas discharged from b), and a four-way switching valve (5) that switches as shown by the solid line in the cooling operation and switches as shown by the dashed line in the heating operation during the cooling operation
An outdoor heat exchanger (6) serving as a condenser during a cooling operation and an evaporator during a heating operation, and two outdoor fans (6a, 6b) attached to the outdoor heat exchanger (6). An outdoor electric expansion valve (8), which is a heat source side electric expansion valve that adjusts the refrigerant flow rate and performs a throttling operation of the refrigerant during a heating operation;
A receiver (9) for storing the liquefied refrigerant and an accumulator (10) are built in as main devices, and each of the devices (1 to 10) is connected to a refrigerant pipe (11) so that the refrigerant can flow therethrough. I have.

FIG. 3 shows a refrigerant piping system of the indoor unit (B). The indoor unit (B) includes an indoor heat exchanger (12) which becomes an evaporator during a cooling operation and a condenser during a heating operation. The fan (12a) is provided, and a use-side electric expansion valve that adjusts a refrigerant flow rate during a heating operation and performs a throttle function of the refrigerant during a cooling operation, on a liquid pipe side of the indoor heat exchanger (12). And a liquid-side communication pipe (11a) and a gas-side communication pipe (11b) through a manual shut-off valve (17a, 17b) to connect with the outdoor unit (A). Have been.

The above devices are connected by a refrigerant pipe (11).
A main refrigerant circuit (14) is connected to the refrigerant so that the refrigerant can flow therethrough, and discharges heat obtained by heat exchange with outdoor air to indoor air.

Next, in the outdoor unit (A), (1)
1e) Discharge gas (hot gas) between the discharge pipe and the liquid pipe side
A bypass path for heating overload control, which is connected to the outdoor heat exchanger (6) in an air passage common to the outdoor heat exchanger (6).
2), a capillary tube (28) and an overload control opening / closing valve (24) that opens when the refrigerant is at a high pressure are sequentially connected in series and in parallel with the outdoor heat exchanger (6). During the heating operation, when the high pressure rises excessively, the overload control on-off valve (24) is turned on or opened, and a part of the discharge gas is transferred from the main refrigerant circuit (14) to the heating overload control bypass passage (11e). I try to bypass .

At this time, a part of the discharged gas is condensed by the auxiliary heat exchanger (22) to assist the capacity of the outdoor heat exchanger (6), and the outdoor heat exchanger (6) is condensed by the capillary tube (28). It is designed to balance the pressure loss on the side.

In addition, (31) cools the suction refrigerant by heat exchange between the suction refrigerant in the suction pipe and the liquid refrigerant in the liquid pipe, thereby increasing the degree of superheat of the refrigerant in the gas side communication pipe (11b). A suction pipe heat exchanger to compensate.

Further, (40a, 40b) is between the liquid pipe between the outdoor electric expansion valve (42a) and the receiver (9) of the main refrigerant circuit (14) and the suction side of each compressor (1a, 1b). And a liquid injection bypass passage for adjusting the degree of superheat of the suction gas during the cooling and heating operation. Each of the bypass passages (40a, 40b) is opened and closed in conjunction with the on / off of the compressor (1). Injection on-off valves (42a, 42b) and capillary tubes (41a, 41b) are provided respectively.

In addition, auxiliary devices are provided in addition to the main devices. (1f) is interposed in the bypass path (11c) of the second compressor (1b), and is connected to the second compressor (1b).
It becomes "open" at the time of stop and unload state of b),
On-off valve for unloader that closes when fully loaded,
(1g) is a capillary tube provided in the bypass passage (11c), (21) is provided in a pressure equalizing hot gas bypass passage (11d) connecting the discharge pipe and the suction pipe,
When the compressor (1) is stopped due to a thermo-off state or the like, an equalizing on-off valve that opens for a predetermined time before restarting, (33a, 33
b) is a capillary tube (32a, 32b) respectively
And an oil return pipe for returning oil from the first and second oil separators (4a, 4b) to the first and second compressors (1a, 1b) through the first and second oil separators.

In the drawing, (HPS) is a high-pressure switch for protecting the compressor, (SP) is a service port, and (GP) is a gauge port.

Here, a number of sensors are arranged in the apparatus. (Th1) is a room temperature thermostat for detecting the indoor temperature, and (Th2) is a liquid side piping temperature T2 of the indoor heat exchanger (12). (Th3) is an indoor gas temperature sensor for detecting the gas-side pipe temperature, and (Th4a, Th4b) are each compressor (1).
a, 1b) a discharge pipe sensor for detecting the discharge pipe temperature, (T
h5) is an external heat exchange sensor that detects the temperature of the liquid pipe of the outdoor heat exchanger (6), and (Th6) is disposed on the suction pipe downstream of the suction pipe heat exchanger (31) and detects the temperature of the suction pipe. (Th7) is an air temperature sensor disposed at the air suction port of the outdoor heat exchanger (6) to detect the temperature of the suction air; (Th8)
a, Th8b) are disposed immediately upstream of the compressors (1a, 1b) of the liquid injection bypass paths (40a, 40b), respectively, and are injection temperature sensors for detecting the temperature of the refrigerant to be injected, and (P1) is cooling. During operation, a high-pressure sensor that detects the high-pressure side pressure of the refrigerant circuit (14), that is, the saturation temperature corresponding to the condensing pressure, (P2) is the refrigerant circuit (14)
Is a low pressure sensor as suction pressure detecting means for detecting the low pressure side pressure, that is, the evaporating pressure equivalent saturation temperature Te. The detected value T6 of the suction pipe sensor (Th6) and the low pressure sensor (P
The superheat degree Sh of the suction refrigerant is detected based on the temperature difference (T6-Te) from the saturation temperature Te corresponding to the evaporation pressure detected in 2), and the suction pipe sensor (Th6) and the low pressure sensor (P2) are detected.
This constitutes a superheat degree detection means (60).

The signals from the sensors can be input to a controller (50) for controlling the operation of the air conditioner. The controller (50) controls the operation of the air conditioner in accordance with the signals from the sensors. Has been made to control. Here, the controller (50) includes a storage circuit (51) for storing various data, a setting circuit (52) for setting a control target value, and the like.

As shown in FIG. 4, the storage capacity (51) of the compressor (1), the indoor liquid temperature sensor (Th2) and the low-pressure sensor (P2) are stored in the storage circuit (51) as shown in FIG. ), The temperature difference ΔTe between the detected values T2 and Te (= T2
-Te) (pressure loss) is related to the gas side communication pipe (1
1b) is stored as a plurality of relational expressions (linear expressions) using the length (average value of each indoor unit (B,...)) As a parameter, and the slopes of the respective relational expressions are corrected coefficients γ1 to γ.
It is 4. As shown in FIG. 5, the relationship between the temperature difference ΔTe (= T2−Te) and the correction coefficient K when each of the relational expressions in FIG. 4 is cut at a position of a fixed capacity fo of the compressor (1). .. Are stored, and it is determined from the temperature difference ΔTe when the compressor (1) is operated at the fixed capacity fo which of the correction coefficients K corresponds to γ1, γ2,.

2 and 3, during the cooling operation of the air conditioner, the four-way switching valve (2) is switched to the solid line side in the drawing.
The refrigerant compressed by the compressor (1) is condensed by the outdoor heat exchanger (6) and the auxiliary heat exchanger (22), sent to each indoor unit (B,...) Via the communication pipe, and electrically driven by each indoor unit. The pressure in the indoor heat exchangers (12,.
...), return to the outdoor unit (A) in a gaseous state, and circulate so as to be sucked into the compressor (1).

During the heating operation, the four-way switching valve (5)
Is switched to the broken line side in the figure, and the flow of the refrigerant is opposite to that in the cooling operation, and the refrigerant compressed in the compressor (1) is condensed in each indoor heat exchanger (12,...) In this state, the air flows into the outdoor unit (A), is depressurized by the outdoor electric expansion valve (8), evaporates in the outdoor heat exchanger (6), and circulates back to the compressor (1).

Here, the content of the control for determining the correction coefficient will be described with reference to the flowchart of FIG.

First, in step ST1, it is determined whether or not an oil return operation is to be performed. In step ST2, the indoor unit (B,
..) Are set to the oil return operation, that is, the indoor electric expansion valve (13) is fully opened, and the indoor fan (12a) is set to the air volume according to the oil return operation. Also, in step ST2,
Each device of the outdoor unit (A) is set to the oil return operation, that is, the outdoor electric expansion valve (8) is fully opened, and the outdoor fan (6a) is operated.
Is controlled to the air volume according to the oil return operation, and the compressor (1) is controlled to the maximum capacity.

Then, in this state, in step ST4,
It is determined whether or not the superheat degree Sh of the suction refrigerant detected by the superheat degree detection means (60) is smaller than a predetermined value α (for example, 3 ° C.). The evaporating pressure-equivalent saturation temperature T2 detected by the liquid temperature sensor (Th2) and the suction pressure-equivalent saturation temperature Te detected by the low pressure sensor (P2) are input, and steps ST6 to ST12 are performed.
Then, according to the temperature difference (T2-Te) between the evaporation pressure equivalent saturation temperature T2 and the suction pressure equivalent saturation temperature Te, as follows:
Change and set the correction coefficient K.

That is, if T2-Te ≦ β1, K =
γ1 is set (step ST7), and β1 <T2-Te ≦
If β2, K = γ2 is set (step ST9), and β
If 2 <T2-Te ≦ β3, K = γ3 is set (step ST11). If none of them is satisfied, the process proceeds to step ST12, where K = γ4.

In the above flow, the set operation control means (53) according to the first aspect of the present invention is constituted by the control of steps ST2 and ST3.
Control constitutes a correction coefficient determining means (54).

FIG. 7 shows the contents of the capacity control of the compressor (1) during the normal cooling operation.
Evaporation pressure equivalent saturation temperature T2 and suction pressure equivalent saturation temperature Te
And, in step SS2, the correction amount Δ of the control target value
Te (pressure loss) is calculated based on the equation ΔTe = K × f, and in step SS3, the control target value Ts is calculated by the equation Ts = Tso
Correction is made based on -ΔTe. Here, Tso is a control target value when the communication pipe length is assumed to be "0", that is, when there is no pressure loss.

That is, as shown in FIG. 8, depending on the set operation, the correction coefficient K is any one of γ1 to γ4 (for example, γ3).
During the cooling operation, a value obtained by subtracting the product of the correction coefficient γ3 and the operating capacity f1 at that time from the control target value Tso assuming that there is no pressure loss is the suction pressure equivalent saturation temperature Te. Is corrected to become the control target value Ts1 of
You.

In step SS4, the capacity f of the compressor (1) is PI-controlled based on the control target value Ts corrected by the above control.

In the above flow, the control of steps SS2 and SS3 constitutes the correcting means (55) according to the second aspect of the present invention.

Therefore, in the above embodiment, when the set operation control means (53) performs an operation for keeping the operating capacity of the compressor (1) constant, the correction coefficient determining means (54) preliminarily stores the memory circuit ( From a plurality of relational expressions between the operating capacity of the compressor (1) and the pressure loss stored in 51), a relational expression corresponding to the communication pipe length of the air conditioner is determined as a correction coefficient. In this case, if the refrigerant state is not a proper wet state but a dry state, the pressure loss differs from the proper state due to an increase in the specific volume even if the operating capacity of the compressor (1) is the same. May be determined, but in the above embodiment, the correction coefficient K is determined when the degree of superheat Sh is equal to or less than the predetermined value α.
Will be determined.

In particular, when the set operation performed by the set operation means (53) is an oil return operation, the oil return operation is performed in the cooling cycle to return the oil in the refrigerant pipe and each device in the indoor electric expansion valve (13). ) Is operated with a large opening degree of about full opening, the refrigerant is in an appropriate wet state, and the operating capacity of the compressor (1) is large, so that the accuracy in determining the relational expression is good. is there. Also, in the air conditioner, providing a separate setting operation mode for determining the correction coefficient K corresponding to the communication pipe length complicates the control configuration, but requires the use of the existing oil return operation mode. Thus, the control configuration can be simplified.

Further, the correction means (55) calculates the product of the correction coefficient K and the operating capacity f of the compressor (1) according to the change in the operating capacity of the compressor (1) during the cooling operation of the air conditioner. Is used to correct the control target value Ts of the capacity control,
The operation control function can be improved.

In the above embodiment, an example in which the present invention is applied to a multi-type air conditioner capable of switching between cooling and heating operations has been described. However, the present invention is not limited to such an embodiment, and the present invention is not limited thereto. The present invention is also applicable to a device in which one indoor unit is connected to an outdoor unit, or a cooling only machine.

[0044]

As described above, according to the first aspect of the present invention, the outdoor unit having the variable displacement compressor and the heat source side heat exchanger, the use side heat exchanger and the use side electric expansion valve are provided. In an air conditioner in which an indoor unit is connected with a liquid-side communication pipe and a gas-side communication pipe to control a compressor capacity during a cooling operation according to a suction pressure equivalent saturation temperature, the operating capacity of the compressor is reduced. When a constant operation is performed and the degree of superheat is smaller than a predetermined value, a relational expression corresponding to the communication pipe length of the air conditioner is obtained from a relational expression between the operating capacity of the compressor and the pressure loss stored in advance. Is determined as a correction coefficient, so that an accurate correction coefficient is determined under an appropriate wet condition, so that reliability and control performance can be improved.

Further, since the set operation for determining the correction coefficient is performed in the oil return operation mode, the relational expression is determined under the appropriate wet condition of the refrigerant and with the large operating capacity of the compressor. It is possible to improve the coefficient determination accuracy and simplify the control configuration by using the existing oil return operation mode.

According to the second aspect of the present invention, in the first aspect of the present invention, the correction coefficient and the operating capacity of the compressor determined according to the change in the operating capacity of the compressor during the cooling operation of the air conditioner. Is used to correct the control target value of the capacity control, so that the control function of the capacity control can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of the present invention.

FIG. 2 is a refrigerant piping system diagram of an outdoor unit of the air conditioner according to the embodiment.

FIG. 3 is a refrigerant piping system diagram of an indoor unit of the air-conditioning apparatus according to the embodiment.

FIG. 4 is a characteristic diagram showing a relational expression between a compressor capacity and a pressure loss stored in advance.

FIG. 5 is a characteristic diagram showing a relationship between a pressure loss and a correction coefficient at a constant capacity.

FIG. 6 is a flowchart illustrating the details of control for determining a correction coefficient.

FIG. 7 is a flowchart showing the contents of a control for correcting a control target value.

FIG. 8 is a characteristic diagram showing a relationship between a capacity of a compressor and correction of a control target value.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 6 Outdoor heat exchanger (heat source side heat exchanger) 11a Liquid side connection pipe 11b Gas side connection pipe 12 Indoor heat exchanger (use side heat exchanger) 13 Indoor electric expansion valve (use side electric expansion valve) 51 Storage circuit (storage means) 53 Setting operation control means 54 Correction coefficient determination means 55 Correction means 60 Superheat degree detection means A Outdoor unit B Indoor unit P2 Low pressure sensor (Suction pressure detection means) Th2 Indoor liquid temperature sensor (Evaporation pressure detection means)

Claims (2)

(57) [Claims] An outdoor unit (A) having a compressor (1) and a heat source side heat exchanger (6) whose operating capacity is variably adjusted, a use side heat exchanger (12) and a use side electric expansion valve. The indoor unit (B) having (13) is connected by a liquid-side communication pipe (11a) and a gas-side communication pipe (11b), and the suction unit detects the saturation temperature corresponding to the suction pressure of the refrigerant in the outdoor unit (A). Pressure detection means (P2)
An air conditioner for controlling the operation capacity of the compressor (1) according to the suction pressure equivalent saturation temperature detected by the suction pressure detecting means (P2) during the cooling operation of the air conditioner. An evaporating pressure detecting means (Th2) for detecting a saturated temperature corresponding to an evaporating pressure of the refrigerant in the use-side heat exchanger (12); an operating capacity of the compressor (1) and a pressure of the refrigerant in a gas-side communication pipe; The relationship with the loss is determined by the gas side communication pipe (11
b) storage means (51) for storing as a plurality of relational expressions using the length as a parameter, a cooling cycle, and the use-side electric expansion valve (1).
3) has a constant large opening and the operating capacity of the compressor (1)
Setting operation control means (53) for controlling the oil return operation state to a constant large capacity, and superheat degree detection means (60) for detecting the degree of superheat of the suction refrigerant during operation by the setting operation control means (53) If, during oPERATION that by the above setting operation control means (53), when the suction superheat degree detected by the superheat degree detecting means (60) is smaller than a predetermined value, the suction pressure detection means (P2) and From the relationship between the difference between the evaporating pressure equivalent saturation temperature and the suction pressure equivalent saturation temperature detected by the evaporating pressure detecting means (Th2) and the operating capacity of the compressor (1), the plurality of storages stored in the storage means (51) are determined. air conditioner, wherein a relational expression corresponding to equation sac Chi communicating絡配tube length and a correction coefficient determination means for determining a correction factor (54). 2. The air conditioner according to claim 1 , wherein the correction coefficient is corrected by the correction coefficient determining means (54) according to a change in the operating capacity of the compressor (1) during the cooling operation of the air conditioner. An air conditioner comprising a correction means (55) for correcting a control target value of the capacity control means (50) using a product of the operating capacity of the compressor (1).