JP5963722B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner.

  Conventionally, a refrigerant circuit configuration of a general air conditioner includes, for example, an outdoor unit and an indoor unit. The outdoor unit includes, for example, a compressor, a four-way valve that switches the refrigerant flow direction, an outdoor heat exchanger, an outdoor blower, a liquid side extension pipe connection valve, and a gas side extension pipe connection valve. The indoor unit includes, for example, an electronic expansion valve that decompresses condensed refrigerant, an indoor heat exchanger, and an indoor blower. The outdoor unit and the indoor unit are connected by, for example, a liquid side extension pipe and a gas side extension pipe (see, for example, Patent Document 1).

  Further, in order to detect the pressure state of the refrigerant circuit, for example, a high pressure sensor is provided in the discharge side pipe of the compressor, and a low pressure sensor is provided in the suction side pipe of the compressor. Further, in order to detect the temperature state of the refrigerant circuit, for example, a thermistor is provided on the refrigerant outlet side during cooling of the outdoor heat exchanger, and between the refrigerant inlet side and the intermediate portion during cooling of the indoor heat exchanger. A thermistor is provided. Further, for example, a control device that controls the refrigerant circuit is provided. The compressor, the four-way valve, and the electronic expansion valve are connected to a control device, and the compressor, the four-way valve, and the electronic expansion valve are controlled by the control device according to various operating conditions (see, for example, Patent Document 1). ).

  In the refrigerant circuit described above, during cooling, the four-way valve is oriented to connect the discharge side path of the compressor to the outdoor heat exchanger, so the outdoor heat exchanger functions as a condenser and exchanges heat in the room. The evaporator is responsible for the evaporator function.

  During the cooling operation, the control device operates the subcool amount on the outlet side of the outdoor unit, which is an outdoor heat exchanger provided in the outdoor unit serving as a condenser, close to the target value SCm1. For example, the control device adjusts the degree of decompression and the refrigerant circulation amount by changing the opening degree of the electronic expansion valve provided in the indoor unit, and sets the subcool amount SC1 on the outlet side of the outdoor unit to the target value SCm1. Adjust to. At that time, the control device does not become a gas-liquid two-phase from the outdoor heat exchanger to the electronic expansion valve on the indoor unit side, but flows into the indoor unit while maintaining the liquid phase state. The subcool amount SC1 is adjusted.

  It is assumed that the refrigerant circuit configuration includes one indoor unit for one outdoor unit, and the refrigerant flows into the indoor unit in a two-phase state. In this case, since the flow disturbance peculiar to the two-phase refrigerant occurs, refrigerant noise is generated at the throttle portion of the electronic expansion valve on the indoor unit side. Therefore, the quietness of the room may be impaired.

  Also, suppose a multi-type refrigerant circuit configuration in which a plurality of indoor units are connected, and the refrigerant flows into the indoor unit in a two-phase state while operating a plurality of indoor units simultaneously. In this case, since the gas phase and the liquid phase are separated in the distribution unit to each indoor unit such as a header, the balance of the refrigerant amount distributed to each indoor unit is lost. Therefore, in a certain indoor unit, a sufficient amount of refrigerant is ensured by extracting the liquid phase-centered refrigerant, and the capacity is extracted. In another indoor unit, since the refrigerant at the center of the gas phase flows in, the operation becomes a shortage of refrigerant and the capacity is not sufficiently extracted. As a result, the operating state of the air conditioner may become unstable.

  By the way, if the pressure on the outlet side of the outdoor unit and the subcooling amount are the same, the phase state of the refrigerant flowing into the electronic expansion valve on the indoor unit side changes due to the influence of the pressure loss generated in the liquid side extension pipe. It is assumed that For example, as the liquid side extension pipe becomes longer, the pressure loss generated in the liquid side extension pipe becomes larger, so that the refrigerant flowing into the electronic expansion valve on the indoor unit side has a higher gas phase ratio. Therefore, generally, target value SCm1 is determined on the assumption that the extension pipe is the maximum value of the product specification.

  However, if the amount of the target value SCm1 is increased, a state in which liquid refrigerant accumulates in the outdoor heat exchanger occurs. Therefore, the heat exchange efficiency of the outdoor heat exchanger decreases, and the condensation pressure of the refrigerant in the outdoor heat exchanger increases. As a result, the difference between the compressor suction pressure and the compressor discharge pressure increases, and the power consumption of the compressor increases. Therefore, the operating efficiency of the air conditioner decreases. Moreover, since liquid refrigerant accumulates in the outdoor heat exchanger, the amount of refrigerant that circulates to the low-pressure side decreases, and thus the cooling capacity decreases.

  Therefore, even before the electronic expansion valve on the indoor unit side, if the target value SCm1 is as small as possible while ensuring a subcool, the operating efficiency of the air conditioner is improved. Therefore, an air conditioner having a specification that can adjust the subcooling amount SC1 to the target value SCm1 in accordance with the length of the liquid side extension pipe is desirable.

  For example, the air conditioner described in Patent Literature 1 calculates the pressure loss of the gas side extension pipe from the suction pressure of the compressor and the saturation pressure of the indoor heat exchanger, and extends the gas side based on the calculated pressure loss. Calculate the length of the pipe. And the air conditioner of patent document 1 calculates the target low pressure etc. at the time of air_conditionaing | cooling operation based on the calculated length of the gas side extension piping, and the air conditioner of the calculated target low pressure etc. Correct the control parameters.

  However, the air conditioner described in Patent Document 1 does not derive the amount of the target value SCm1 from the liquid side extended pipe length. Therefore, the air conditioner described in Patent Document 1 does not adjust the subcool amount SC1 to the target value SCm1 in accordance with the length of the liquid side extension pipe.

JP 2006-183979 A (Claim 1)

  As described above, conventionally, during the cooling operation, the electronic expansion valve of the indoor unit adjusts the opening so that the subcool amount SC1 of the outdoor heat exchanger follows the target value SCm1. Here, the subcool amount SC1 needs to be adjusted to an amount that can secure the outlet-side subcool amount of the outdoor unit just before the electronic expansion valve of the indoor unit.

  However, as the liquid side extension pipe length increases, the pressure loss generated in the liquid side extension pipe increases, and as the pressure loss generated in the liquid side extension pipe increases, the refrigerant gas in front of the electronic expansion valve of the indoor unit increases. The proportion of phases increases. Therefore, the target value SCm1 is set assuming that the liquid side extension pipe is the maximum value of the product specification.

  However, if the target value SCm1 becomes excessively large, the heat exchange efficiency of the outdoor heat exchanger decreases, and the condensation pressure of the refrigerant in the outdoor heat exchanger increases. Therefore, as described above, since the power consumption of the compressor increases, the energy saving performance decreases. In addition, if the target value SCm1 becomes excessively large, the amount of circulating refrigerant decreases, so that the cooling capacity decreases.

  Therefore, it is desirable to adjust the subcooling amount SC1 to the target value SCm1 according to the pressure loss amount generated in the liquid side extension pipe. However, in order to grasp the pressure loss amount, the electronic expansion valve provided in the indoor unit The cost increases because it is necessary to add a sensor for detecting the front pressure.

  Moreover, the conventional air conditioner as described in Patent Document 1 calculates the amount of pressure loss generated in the gas side extension pipe length by calculation without adding a sensor, but according to the liquid side extension pipe length. The target subcool amount SCm1 on the outlet side of the outdoor unit is not derived.

  In other words, the conventional air conditioner cannot adjust the subcool amount on the outlet side of the outdoor unit without excessively increasing it, and cannot return the refrigerant to the indoor unit while remaining in the liquid phase single phase. was there.

  The present invention has been made to solve the above-described problems. By adjusting the amount of subcooling on the outlet side of the outdoor unit without excessively increasing it, the indoor unit remains in the liquid phase single phase. It aims at providing the air conditioner which can return a refrigerant | coolant.

  An air conditioner according to the present invention includes a compressor that compresses and discharges a refrigerant, an outdoor heat exchanger, a first expansion valve, an indoor heat exchanger, the compressor, and the outdoor heat exchanger. An outdoor unit, an indoor unit including the indoor heat exchanger, a gas side extension pipe, a liquid side extension pipe, a thermistor for detecting the evaporation temperature of the indoor heat exchanger, and an intake side suction of the compressor A sensor for detecting pressure, and a control device for controlling the opening of the first expansion valve, and through the gas side extension pipe and the liquid side extension pipe, the outdoor unit, the indoor unit, Is connected to the compressor, the outdoor heat exchanger, the first expansion valve, and the indoor heat exchanger in order to form a refrigerant circuit, and the control device includes: The first corresponding to the pressure loss of the gas side extension pipe A correlation is set between the power loss, the first pipe length corresponding to the length of the gas side extension pipe, and the first refrigerant circulation amount corresponding to the refrigerant amount circulating in the refrigerant circuit. The second pressure loss corresponding to the pressure loss on the low-pressure side of the refrigerant circuit is obtained based on the detection results of the thermistor and the sensor as the first pressure loss, and the first refrigerant circulation amount is obtained. Correspondingly, a second refrigerant circulation amount corresponding to the driving of the compressor is obtained, and the first pipe length is obtained based on the second pressure loss, the second refrigerant circulation amount, and the correlation, The second pipe length corresponding to the length of the liquid side extension pipe is obtained from the first pipe length, the third pressure loss of the liquid side extension pipe obtained according to the second pipe length, and the outdoor heat exchange. Flow into the first expansion valve based on the condensing pressure of the vessel. An upstream pressure of the refrigerant to be obtained, a first liquid side saturation temperature corresponding to the upstream pressure is obtained, a second liquid side saturation temperature of the refrigerant flowing through the outdoor heat exchanger is obtained, and the first liquid side saturation is obtained. Based on the temperature and the second liquid side saturation temperature, a target on the outlet side of the outdoor heat exchanger, as a subcooling amount for maintaining the liquid phase state of the refrigerant flowing into the first expansion valve, A first subcool amount is derived, and an opening degree of the first expansion valve is controlled according to the first subcool amount.

  In order to appropriately control the subcooling amount on the outlet side of the outdoor unit obtained based on the correlation between the low pressure loss, the gas extension pipe length corresponding to the liquid side extension pipe length, and the refrigerant circulation amount, The refrigerant can be returned to the indoor unit while remaining in the liquid phase single phase. Therefore, the subcooling amount on the outlet side of the outdoor unit can be appropriately controlled according to the length of the liquid side extension pipe. Therefore, there is an effect that it is possible to provide an air conditioner that can prevent an increase in the necessary refrigerant amount while preventing a decrease in operating efficiency related to cooling.

It is a figure which shows an example of the refrigerant circuit structure of the air conditioner 1 in Embodiment 1 of this invention. It is a figure which shows an example of the function structure of the control apparatus 51 for outdoor units in Embodiment 1 of this invention. It is a figure which shows an example of the correlation of the low voltage | pressure loss loss (DELTA) Ps, refrigerant | coolant circulation amount Gr, and the gas side extension piping length in Embodiment 1 of this invention. It is a figure which shows an example of the Mollier diagram corresponding to the refrigerant circuit of the air conditioner 1 in Embodiment 1 of this invention. It is a flowchart explaining the example of control of the air conditioner 1 in Embodiment 1 of this invention. It is a figure which shows an example of the refrigerant circuit structure of the air conditioner 1 in Embodiment 2 of this invention. It is a figure which shows an example of a function structure of the control apparatus 51 for outdoor units in Embodiment 2 of this invention. It is a figure which shows an example of the Mollier diagram corresponding to the refrigerant circuit of the air conditioner 1 in Embodiment 2 of this invention. It is a flowchart explaining the example of control of the air conditioner 1 in Embodiment 2 of this invention. It is a figure which shows an example of the refrigerant circuit structure of the air conditioner 1 in Embodiment 3 of this invention. It is a figure which shows an example of a function structure of the control apparatus 51 for outdoor units in Embodiment 3 of this invention. It is a flowchart explaining the example of control of the air conditioner 1 in Embodiment 3 of this invention. It is a figure which shows an example of the refrigerant circuit structure of the air conditioner 1 in Embodiment 4 of this invention. It is a figure which shows an example of a function structure of the control apparatus for outdoor units 51 in Embodiment 4 of this invention. It is a flowchart explaining the example of control of the air conditioner 1 in Embodiment 4 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, although the step which describes the program which performs operation | movement of Embodiment 1-4 of this invention is a process performed in time series along the order described, it does not necessarily process in time series, it is parallel Processing that is executed manually or individually may also be included.

  It does not matter whether each function described in the first to fourth embodiments is realized by hardware or software. That is, each block diagram described in the first to fourth embodiments may be considered as a hardware block diagram or a software functional block diagram. For example, each block diagram may be realized by hardware such as a circuit device, or may be realized by software executed on an arithmetic device such as a processor (not shown).

  In addition, each block in the block diagrams described in the first to fourth embodiments only needs to have its function implemented, and the configuration may not be separated by each block.

  Moreover, each refrigerant circuit demonstrated by this Embodiment 1-4 shows an example, and is not limited to the description matter shown in figure.

  In each of the first to fourth embodiments, items not particularly described are the same as those in the first to fourth embodiments, and the same functions and configurations are described using the same reference numerals.

  Moreover, this Embodiment 1-4 may be implemented independently and may be implemented in combination. In either case, the advantageous effects described below can be obtained.

  Moreover, the setting examples of various values and flags described in each of the first to fourth embodiments are merely examples, and are not particularly limited thereto.

  In the first to fourth embodiments, the system represents the entire apparatus composed of a plurality of apparatuses or the entire function composed of a plurality of functions.

Embodiment 1 FIG.
<Summary of invention>
FIG. 1 is a diagram illustrating an example of a refrigerant circuit configuration of an air conditioner 1 according to Embodiment 1 of the present invention. The air conditioner 1 according to Embodiment 1 shown in FIG. 1 controls, for example, according to the target subcool amount SCm1 during cooling operation. Although details will be described later, the air conditioner 1 sets the subcool amount SCm1 obtained based on the correlation between the low pressure loss ΔPs, the gas extension pipe length corresponding to the liquid side extension pipe length, and the refrigerant circulation amount Gr. Accordingly, the subcool amount SC1 on the outlet side of the outdoor unit 13 is appropriately controlled.

  Therefore, the air conditioner 1 adjusts the subcool amount SC1 on the outlet side of the outdoor unit 13 without excessively increasing without adding a sensor for detecting the pressure loss amount of the liquid side extension pipe 15. The refrigerant is returned to the unit 11 while remaining in the liquid phase single phase. Therefore, the air conditioner 1 appropriately controls the subcooling amount SC1 on the outlet side of the outdoor unit 13 according to the length of the liquid side extension pipe 15 while avoiding an increase in cost. Therefore, the air conditioner 1 avoids an increase in the amount of necessary refrigerant while preventing a decrease in operating efficiency related to cooling. Details will be described below.

<Structure of the invention>
As shown in FIG. 1, a compressor circuit, a four-way valve 23, an outdoor heat exchanger 25, a first electronic expansion valve 27, and an indoor heat exchanger 29 are connected to the air conditioner 1 in this order to form a refrigerant circuit. Has been. The air conditioner 1 includes an indoor unit 11 and an outdoor unit 13. The indoor unit 11 and the outdoor unit 13 are connected via a liquid side extension pipe 15 and a gas side extension pipe 17. The air conditioner 1 includes an outdoor blower 31, an indoor blower 33, and the like.

  The air conditioner 1 includes a gas-side extension pipe connection valve 35, a liquid-side extension pipe connection valve 37, and the like. The air conditioner 1 includes a high pressure sensor 41, a low pressure sensor 43, a liquid-side first thermistor 45, an outdoor heat exchanger intermediate temperature thermistor 47, an indoor heat exchanger thermistor 49, and the like. The air conditioner 1 includes an outdoor unit controller 51, an indoor unit controller 53, and the like.

  The air conditioner 1 includes an indoor unit 11 and an outdoor unit 13. The indoor unit 11 and the outdoor unit 13 are connected via a liquid side extension pipe 15 and a gas side extension pipe 17. The outdoor unit 13 includes a compressor 21, a four-way valve 23, and an outdoor heat exchanger 25 as part of the refrigerant circuit. The outdoor unit 13 is provided with a liquid side extension pipe connection valve 37 as a connection port of the liquid side extension pipe 15. The outdoor unit 13 is provided with a gas side extension pipe connection valve 35 as a connection port of the gas side extension pipe 17. The outdoor unit 13 is provided with an outdoor fan 31, and the outdoor fan 31 is disposed near the outdoor heat exchanger 25.

  The outdoor unit 13 includes a high pressure sensor 41, a low pressure sensor 43, a liquid side first thermistor 45, an outdoor heat exchanger intermediate temperature thermistor 47, and an outdoor unit controller 51. If the air conditioner 1 is in the cooling operation, the high pressure sensor 41 is provided between the discharge side of the compressor 21 and the outdoor heat exchanger 25, and the outdoor heat exchanger 25 is a condenser. The condenser pressure Pd at the time of performing the function is detected, and the detection result is supplied to the outdoor unit controller 51. The outdoor unit controller 51 can derive the condenser-side saturation temperature, that is, the liquid-side saturation temperature Tc by converting the condenser pressure Pd into the saturation pressure.

  In addition, it is not specifically limited about the mounting form of saturation pressure conversion. For example, a derivation formula may be set and derived from the derivation formula using various parameters. Moreover, you may derive | lead-out using the mapping table which set the correlation with various pressures and various saturation temperature. In this case, if a direct correlation is not set, various parameters may be derived by executing an interpolation process or the like.

  If the air conditioner 1 is in the cooling operation, the low pressure sensor 43 is provided between the suction side of the compressor 21 and the indoor heat exchanger 29, and the suction on the suction side of the compressor 21 is performed. The pressure Ps is detected, and the detection result is supplied to the outdoor unit controller 51. The liquid side first thermistor 45 is provided on the outlet side of the outdoor heat exchanger 25, detects the outlet temperature Tout of the outdoor heat exchanger 25, and supplies the detection result to the outdoor unit controller 51.

  The outdoor heat exchanger intermediate temperature thermistor 47 is disposed at a substantially central portion of the outdoor heat exchanger 25, and detects the condenser side saturation temperature, that is, the liquid side saturation temperature Tc when the air conditioner 1 is in cooling operation. Then, the detection result is supplied to the outdoor unit controller 51. Therefore, the outdoor heat exchanger intermediate temperature thermistor 47 can detect the liquid side saturation temperature Tc.

  Further, the outdoor unit controller 51 can derive the condenser pressure Pd from the refrigerant pressure corresponding to the liquid side saturation temperature Tc. That is, the outdoor unit controller 51 can derive the condenser pressure Pd by converting the liquid side saturation temperature Tc into the saturation pressure. Therefore, the air conditioner 1 can obtain the condenser pressure Pd and the liquid side saturation temperature Tc by using the detection result of either the high pressure sensor 41 or the outdoor heat exchanger intermediate temperature thermistor 47.

  The indoor unit 11 includes a first electronic expansion valve 27 and an indoor heat exchanger 29 as part of the refrigerant circuit. Here, it is assumed that the refrigerant flow during cooling is used as a reference. In this case, the liquid side extension pipe 15 is connected to the upstream side of the first electronic expansion valve 27, the gas side extension pipe 17 is connected to the downstream side of the indoor heat exchanger 29, and the upstream side of the indoor heat exchanger 29. That is, an indoor heat exchanger thermistor 49 is provided on the inlet side of the indoor heat exchanger 29. The indoor unit 11 is provided with an indoor blower 33, and the indoor blower 33 is disposed near the indoor heat exchanger 29.

  The indoor heat exchanger thermistor 49 is provided in an intermediate portion from the inlet side of the indoor heat exchanger 29. When the air conditioner 1 is in the cooling operation, the indoor heat exchanger 29 functions as an evaporator. Is detected, and the detection result is supplied to the indoor unit controller 53. Note that the indoor unit control device 53 can derive the evaporation pressure Pe of the indoor heat exchanger 29 by converting the evaporation temperature Te into a saturation pressure.

  The outdoor unit control device 51 performs various calculations according to detection results of various sensors such as the high pressure sensor 41, the low pressure sensor 43, the liquid side first thermistor 45, and the outdoor heat exchanger intermediate temperature thermistor 47, thereby compressing the compressor. The compressor 21 is commanded to the compressor 21. The indoor unit control device 53 receives the detection result of the indoor heat exchanger thermistor 49. The indoor unit controller 53 and the outdoor unit controller 51 communicate with each other, exchange detection results of various sensors, and supply various control commands to each other.

  For example, when the air conditioner 1 is in the cooling operation, the outdoor heat exchanger 25 actually secures the first electronic expansion valve 27 in accordance with a control command from the outdoor unit controller 51 or the indoor unit controller 53. The opening / closing operation is performed so that the subcooling amount SC1 approaches the subcooling amount SCm1, which is the range in which the refrigerant maintains the liquid phase single phase. Here, the subcooling amount SC1 is derived by subtracting the outlet temperature Tout of the outdoor heat exchanger 25 from the liquid side saturation temperature Tc.

  The subcool amount SCm1 is derived by subtracting the liquid side saturation temperature Tm on the upstream side of the first electronic expansion valve 27 from the liquid side saturation temperature Tc. That is, the subcool amount SCm1 is derived by subtracting the liquid side saturation temperature Tm of the refrigerant flowing into the first electronic expansion valve 27 from the liquid side saturation temperature Tc. Then, the outdoor unit controller 51 or the indoor unit controller 53, that is, the air conditioner 1, determines the opening degree of the first electronic expansion valve 27 from the difference between the subcool amount SC1 and the subcool amount SCm1, The one electronic expansion valve 27 performs an operation of adjusting the opening degree of the first electronic expansion valve 27.

  The indoor unit controller 53 operates in response to a command from a remote controller (not shown) or an external terminal, and supplies various control commands accompanying the operation to the outdoor unit controller 51.

  Note that the outdoor unit 13 may not include the four-way valve 23. In this case, if the discharge side of the compressor 21 and the outdoor heat exchanger 25 are connected, the air conditioner 1 can perform a cooling operation. The outdoor unit 13 may not include the gas side extension pipe connection valve 35 and the liquid side extension pipe connection valve 37. In this case, for example, a pipe connecting the indoor unit 11 and the outdoor unit 13 may be connected by a fastener or the like.

  In addition, about the pressure sensors, such as the high voltage sensor 41 and the low voltage sensor 43, the mounting form is not specifically limited. Moreover, about the temperature sensors, such as the liquid side 1st thermistor 45, the outdoor heat exchanger intermediate temperature thermistor 47, and the indoor heat exchanger thermistor 49, the mounting form is not specifically limited, It is not necessary to be a thermistor.

  The indoor heat exchanger thermistor 49 corresponds to the thermistor in the present invention. The low pressure sensor 43 corresponds to the sensor in the present invention. The outdoor unit controller 51 corresponds to the controller in the present invention. The first electronic expansion valve 27 corresponds to the first expansion valve in the present invention. The gas side extension pipe connection valve 35 corresponds to the first connection valve in the present invention. The liquid side extension pipe connection valve 37 corresponds to the second connection valve in the present invention. Further, the subcool amount SC1 corresponds to the second subcool amount in the present invention. Further, the subcool amount SCm1 corresponds to the first subcool amount in the present invention. Further, the condenser pressure Pd corresponds to the condensation pressure in the present invention.

  Next, the functional configuration of the outdoor unit controller 51 will be described. The outdoor unit control device 51 estimates the amount of pressure loss generated in the liquid side extension pipe 15 from the low pressure pressure loss ΔPs without adding a pressure sensor to the refrigerant circuit configured in the air conditioner 1, and the subcool amount SC1. Is appropriately controlled within the range of the subcool amount SCm1.

  For example, during the cooling operation, the outdoor unit control device 51 is provided on the upstream side of the indoor heat exchanger 29, that is, the indoor heat exchanger thermistor 49 disposed between the inlet and the center of the indoor heat exchanger 29. The evaporation pressure Pe is obtained by converting the liquid side saturation temperature Tm, which is the detection result, into a saturation pressure. Next, the outdoor unit controller 51 derives the low pressure loss ΔPs generated in the gas side extension pipe 17 from the difference between the evaporation pressure Pe and the suction pressure Ps of the compressor 21 detected by the low pressure sensor 43. .

  Next, the outdoor unit controller 51 estimates the length of the gas side extension pipe 17 from the low pressure loss ΔPs. Next, the outdoor unit controller 51 estimates the length of the liquid side extension pipe 15 from the length of the gas side extension pipe 17. Next, the outdoor unit controller 51 derives the subcooling amount SCm1 from the length of the liquid side extension pipe 15. Then, the outdoor unit controller 51 adjusts the subcool amount SC1 on the outlet side of the outdoor heat exchanger 25 within the range of the target subcool amount SCm1 on the outlet side of the outdoor heat exchanger 25. Next, a specific functional configuration of the outdoor unit control device 51 will be described with reference to FIG.

  FIG. 2 is a diagram illustrating an example of a functional configuration of the outdoor unit control device 51 according to Embodiment 1 of the present invention. As illustrated in FIG. 2, the outdoor unit control device 51 includes, for example, a refrigerant circulation amount deriving unit 101, a low-pressure pressure loss deriving unit 103, a first mapping table 105, a gas side extended pipe length deriving unit 107, and a second mapping table. 109, liquid side extended pipe length deriving unit 111, pressure loss deriving unit 113, pressure calculating unit 115, liquid side saturation temperature deriving unit 117, subcooling amount deriving unit 119, subcooling amount determining unit 121, expansion valve opening degree controlling unit 123, And a timer 125.

The refrigerant circulation amount deriving unit 101 derives a refrigerant circulation amount Gr corresponding to the refrigerant amount circulating in the refrigerant circuit configured in the air conditioner 1. Specifically, the refrigerant circulation amount deriving unit 101 derives an approximate compressor intake gas density ρ (kg / m ³ ) from the intake pressure Ps of the compressor 21 detected by the low pressure sensor 43. Next, the refrigerant circulation amount deriving unit 101 includes a compressor stroke volume V _st (cc), an operating frequency fz (rps), a compressor intake gas density ρ (kg / m ³ ), and a volume efficiency η _v (dimensionless number). Is applied to the following equation (1) to derive the refrigerant circulation amount Gr (kg / h).

Incidentally, the compressor suction gas specific volume V _g instead of the compressor suction gas density ρ (kg / m ³⁾ may be used. In this case, the refrigerant circulation amount deriving unit 101 integrates 1 / V _g instead of the compressor intake gas density ρ (kg / m ³ ). In addition, the refrigerant circulation amount deriving unit 101 predefines a mapping table corresponding to the above equation (1), and performs an interpolating process or the like when a parameter for which the correspondence relationship is not defined is generated, whereby the refrigerant circulation amount Gr. (Kg / h) may be obtained.

  The low pressure pressure loss deriving unit 103 derives a low pressure loss ΔPs generated in the gas side extension pipe 17 on the low pressure side in the refrigerant circuit configured in the air conditioner 1. Specifically, as described above, the low pressure pressure loss deriving unit 103 increases the evaporation pressure Pe of the indoor heat exchanger 29 that serves as an evaporator during the cooling operation from the inlet of the indoor heat exchanger 29 to the central portion. It calculates | requires by converting into saturation pressure from the liquid side saturation temperature Tm which is a detection result of the indoor heat exchanger thermistor 49 arrange | positioned between. Next, the low pressure pressure loss deriving unit 103 acquires the suction pressure Ps of the compressor 21 detected by the low pressure sensor 43. Next, the low pressure pressure loss deriving unit 103 derives the low pressure loss ΔPs generated in the gas side extension pipe 17 from the difference between the evaporation pressure Pe and the suction pressure Ps.

  In the first mapping table 105, a correlation among the refrigerant circulation amount Gr, the low pressure loss ΔPs, and the gas side extension pipe length is set. That is, in the first mapping table 105, the refrigerant circulation amount Gr, the low pressure loss ΔPs, and the gas side extension pipe length are logically linked to each other. For example, the first mapping table 105 is set such that the gas-side extension pipe length is uniquely determined by determining the low pressure loss ΔPs and the refrigerant circulation amount Gr. Details of the correlation among the refrigerant circulation amount Gr, the low pressure loss ΔPs, and the gas side extension pipe length set in the first mapping table 105 will be described later with reference to FIG.

  Of the low pressure loss ΔPs, the one set in the first mapping table 105 corresponds to the first pressure loss in the present invention. Of the low-pressure pressure loss ΔPs, the one derived by the low-pressure pressure loss deriving unit 103 corresponds to the second pressure loss in the present invention. Further, the refrigerant circulation amount Gr set in the first mapping table 105 corresponds to the first refrigerant circulation amount in the present invention. Further, the refrigerant circulation amount Gr derived by the refrigerant circulation amount deriving unit 101 corresponds to the second refrigerant circulation amount in the present invention.

  Further, the gas side extended pipe length corresponds to the first pipe length in the present invention. Further, the liquid side extended pipe length corresponds to the second pipe length in the present invention. Further, the pressure loss ΔPd corresponds to the third pressure loss in the present invention. Further, the liquid side saturation temperature Tm corresponds to the first liquid side saturation temperature in the present invention. The liquid side saturation temperature Tc corresponds to the second liquid side saturation temperature in the present invention. Further, the pressure Pm before the first electronic expansion valve 27 corresponds to the upstream pressure of the refrigerant flowing into the first expansion valve in the present invention.

  The gas side extension pipe length deriving unit 107 is set by the first mapping table 105, the refrigerant circulation amount Gr derived by the refrigerant circulation amount deriving unit 101, the low pressure loss ΔPs derived by the low pressure pressure loss deriving unit 103, and the first mapping table 105. Based on the correlation, the gas side extension pipe length corresponding to the length of the gas side extension pipe 17 is derived.

  In the second mapping table 109, the gas-side extension pipe length is associated with the liquid-side extension pipe length. For example, when the gas-side extension pipe length and the liquid-side extension pipe length can be regarded as the same length, the gas-side extension is not performed in the second mapping table 109 without performing the weighting calculation. A correspondence that uniquely specifies the liquid side extension pipe length from the pipe length is set.

  Further, for example, when the gas side extension pipe length and the liquid side extension pipe length are different from each other, a weighting operation set in advance in the second mapping table 109 is executed, so that the gas side extension pipe length is obtained. A correspondence that uniquely specifies the liquid side extension pipe length from the pipe length is set.

  In short, in the second mapping table 109, association is set so that the liquid side extension pipe length corresponding to the length of the liquid side extension pipe 15 can be obtained from the gas side extension pipe length.

  The liquid-side extension pipe length deriving unit 111 is based on the gas-side extension pipe length derived by the gas-side extension pipe length deriving unit 107 and the corresponding relationship set in the second mapping table 109. The length of the liquid side extension pipe corresponding to the length of is derived.

  In addition, although the example in which the correlation between the refrigerant circulation amount Gr, the low pressure loss ΔPs, and the gas side extension pipe length is defined as the first mapping table 105 has been described, the present invention is not particularly limited thereto. For example, a derivation formula for deriving these correlations may be defined. Further, although an example in which the correspondence relationship between the gas side extension pipe length and the liquid side extension pipe length is defined as the second mapping table 109 has been described, the present invention is not particularly limited thereto.

  For example, the calculation may be advanced by regarding the gas side extension pipe length and the liquid side extension pipe length as the same. Further, for example, a derivation formula for deriving the liquid side extension pipe length from the gas extension pipe length may be defined. In short, as long as the mapping relationship between the refrigerant circulation amount Gr and the low-pressure pressure loss ΔPs and the gas-side extension pipe length is set, the mounting form is not particularly limited.

  The pressure loss deriving unit 113 derives the pressure loss ΔPd generated in the liquid side extension pipe 15 based on the liquid side extension pipe length. Specifically, the pressure loss deriving unit 113 derives the pressure loss ΔPd by using, for example, the Darcy-Weissbach equation (2) represented by the following equation.

  Here, λ represents the Darcy tube friction coefficient. Δx represents the liquid side extension pipe length. D represents the inner diameter of the liquid side extension pipe 15. u represents the average flow rate. Note that ρ represents the compressor intake gas density ρ as described above.

  The method for deriving the pressure loss ΔPd is not limited to the above description. For example, the mapping table may be set so that the pressure loss ΔPd is uniquely derived from the various parameters described above. In this case, even if the corresponding parameter is not set directly, the pressure loss deriving unit 113 may obtain the pressure loss ΔPd by executing an interpolation process or the like.

  The pressure calculation unit 115 obtains the pressure Pm before the first electronic expansion valve 27, that is, the pressure Pm on the upstream side of the first electronic expansion valve 27, based on the pressure loss ΔPd and the condenser pressure Pd. For example, the pressure calculation unit 115 obtains the pressure Pm by subtracting the pressure loss ΔPd from the condenser pressure Pd.

  The liquid side saturation temperature deriving unit 117 derives the liquid side saturation temperature Tm corresponding to the pressure Pm before the first electronic expansion valve 27 by converting the saturation pressure. The liquid side saturation temperature deriving unit 117 derives the liquid side saturation temperature Tc corresponding to the condenser pressure Pd, for example, by converting the saturation pressure.

  The subcooling amount deriving unit 119 derives the subcooling amount SCm1 necessary for maintaining the single-phase refrigerant before the first electronic expansion valve 27, that is, the target subcooling amount SCm1 on the outlet side of the outdoor heat exchanger 25. . The subcooling amount deriving unit 119 derives the subcooling amount SC1 actually secured by the outdoor heat exchanger 25, that is, the subcooling amount SC1 on the outlet side of the outdoor heat exchanger 25. Specifically, the subcool amount deriving unit 119 derives the subcool amount SCm1 by subtracting the liquid side saturation temperature Tm from the liquid side saturation temperature Tc. The subcool amount deriving unit 119 derives the subcool amount SC1 by subtracting the outlet temperature Tout of the outdoor heat exchanger 25 detected by the liquid side first thermistor 45 from the liquid side saturation temperature Tc.

  The subcool amount determination unit 121 determines whether or not the subcool amount SC1 on the outlet side of the outdoor heat exchanger 25 is within the target subcool amount SCm1 on the outlet side of the outdoor heat exchanger 25. Specifically, the subcool amount determination unit 121 determines whether SCm1−α1 ≦ SC1 ≦ SCm1 + β1. Here, α1 and β1 are arbitrary constants for defining the stable range of the subcool amount SC1.

  When SC1> SCm1 + β1, the expansion valve opening degree control unit 123 supplies the first electronic expansion valve 27 with an opening degree update command for renewing the opening degree of the first electronic expansion valve 27 compared to the present time. When SC1 <SCm1-α1, the expansion valve opening degree control unit 123 supplies the first electronic expansion valve 27 with an opening degree update command for updating the opening degree of the first electronic expansion valve 27 to be closed compared to the current time. To do.

  The timer 125 counts the predetermined time a1 in order to hold the predetermined time a1 after the opening degree of the first electronic expansion valve 27 is updated. The time measuring unit 125 makes the subcool amount determination unit 121 make the determination regarding the subcool amount SC1 and the subcool amount SCm1 described above until the predetermined time b1 elapses after the opening degree of the first electronic expansion valve 27 is updated. Supply the command to be performed. The time measuring unit 125 issues a command to restart the process of deriving the subcooling amount SCm1 after the fixed time b1 has elapsed after the opening degree of the first electronic expansion valve 27 is updated. Supply to pressure loss deriving unit 103. Here, in consideration of the stability of the refrigerant circuit, the timer unit 125 is set to satisfy a1 <b1.

  In addition, although the various function structure demonstrated above demonstrated the example provided in the outdoor unit control apparatus 51, it does not specifically limit to this. For example, the various functional configurations described above may be provided in the indoor unit control device 53. The various functional configurations described above may be provided in an external device (not shown). For example, the various functional configurations described above may be incorporated in a HEMS (Home Energy Management System). Further, the various functional configurations described above may be incorporated in a server device provided outside (not shown). The various functional configurations described above may be incorporated in a portable device such as a tablet terminal (not shown).

<Principle of the invention>
Next, the principle of deriving the subcool amount SCm1 in the air conditioner 1 according to Embodiment 1 will be described with reference to FIGS. FIG. 3 is a diagram showing an example of a correlation among the low pressure loss ΔPs, the refrigerant circulation amount Gr, and the gas side extension pipe length in the first embodiment of the present invention. For example, for the same low-pressure pressure loss ΔPs, a correlation is set in which the gas-side extension pipe length becomes longer as the refrigerant circulation amount Gr becomes smaller. For the same low-pressure pressure loss ΔPs, a correlation is set in which the gas-side extension pipe length is shortened as the refrigerant circulation amount Gr increases. In any case, if the low-pressure pressure loss ΔPs and the refrigerant circulation amount Gr are determined, a correlation is established so that the corresponding gas-side extension pipe length can be obtained.

  If the correlation among the low-pressure pressure loss ΔPs, the refrigerant circulation amount Gr, and the gas-side extension pipe length is known in advance by actual measurement or trial calculation, etc., processing is performed so that the gas-side extension pipe length is uniquely determined as appropriate. It can be realized with a possible implementation.

  For example, a data structure in which the low pressure loss ΔPs, the refrigerant circulation amount Gr, and the gas side extension pipe length are logically associated may be set. Further, a derivation algorithm for obtaining the gas-side extension pipe length from the low pressure loss ΔPs and the refrigerant circulation amount Gr may be implemented. In any case, the correlation among the low-pressure pressure loss ΔPs, the refrigerant circulation amount Gr, and the gas-side extension pipe length may be determined.

  FIG. 4 is a diagram illustrating an example of a Mollier diagram corresponding to the refrigerant circuit of the air conditioner 1 according to Embodiment 1 of the present invention. As shown in FIG. 4, if the subcooling amount SCm1 is determined so that the liquid side saturation temperature Tm changes on the saturated liquid line, and the subcooling amount SC1 is adjusted within the range of the subcooling amount SCm1, the outdoor heat exchanger The refrigerant from the outlet side of 25 to the front of the first electronic expansion valve 27 is maintained in a liquid phase state. Therefore, the subcool amount SC1 on the outlet side of the outdoor heat exchanger 25, that is, the subcool amount SC1 on the outlet side of the outdoor unit 13 is adjusted without being excessively increased.

  For example, as the gas side extension pipe 17 becomes longer, the liquid side extension pipe 15 becomes longer. As the liquid side extension pipe 15 becomes longer, the pressure loss ΔPd of the liquid side extension pipe 15 increases. Then, in accordance with the displacement of the pressure loss ΔPd of the liquid side extension pipe 15, the liquid side saturation temperature Tm is calculated so as to change on the saturated liquid line.

  Therefore, the target subcooling amount SCm1 on the outlet side of the outdoor heat exchanger 25, that is, the target subcooling amount SCm1 on the outlet side of the outdoor unit 13, is the length of the gas side extension pipe 17 and the liquid side extension pipe 15. It is adjusted accordingly. As a result, the refrigerant is returned to the indoor heat exchanger 29 with the liquid phase single phase ensuring a subcool. Moreover, since the subcool amount SCm1 is not set to an excessively large amount, the heat exchange efficiency does not decrease in the outdoor heat exchanger 25, and the refrigerant does not accumulate in the outdoor heat exchanger 25 too much.

  Here, the subcool amount SC1 is obtained from the high pressure sensor 41 and the liquid-side first thermistor 45 provided in advance in the refrigerant circuit by the calculation described above. As described above, the subcool amount SCm1 is obtained based on the condenser pressure Pd and the pressure loss ΔPd of the liquid side extension pipe 15. The condenser pressure Pd is obtained by the high pressure sensor 41. The pressure loss ΔPd of the liquid side extension pipe 15 is obtained from the correlation among the low pressure loss ΔPs, the refrigerant circulation amount Gr, and the gas side extension pipe length. The refrigerant circulation amount Gr is obtained based on the detection result of the low-pressure sensor 43 or the like provided in advance in the refrigerant circuit. The low-pressure pressure loss ΔPs is obtained based on the detection results of the low-pressure sensor 43 and the indoor heat exchanger thermistor 49.

  Therefore, since the air conditioner 1 does not require installation of a sensor such as a pressure sensor in front of the first electronic expansion valve 27, an increase in cost can be avoided. Therefore, the air conditioner 1 has an inexpensive circuit configuration. Further, the air conditioner 1 has a correlation between the low-pressure pressure loss ΔPs, the refrigerant circulation amount Gr, and the gas-side extension pipe length, depending on the length of the liquid-side extension pipe 15. Since the subcooling amount SC1 is controlled so as to follow the target subcooling amount SCm1 on the outlet side of the outdoor unit 13, it is possible to prevent a decrease in operating efficiency related to cooling and avoid an increase in the necessary amount of refrigerant. it can. Next, an operation example of the air conditioner 1 based on the various configurations and principles described above will be described with reference to FIG.

<Operation of the Invention>
FIG. 5 is a flowchart illustrating a control example of the air conditioner 1 according to Embodiment 1 of the present invention. In the following description of the operation, it is assumed that the outdoor unit 13 in which the outdoor unit control device 51 is incorporated is the controlling entity.

(Step S11)
The outdoor unit 13 determines whether or not an operation command has arrived from the indoor unit 11. When the outdoor unit 13 does not receive the operation command from the indoor unit 11, the outdoor unit 13 returns to Step S11. On the other hand, when the operation command arrives from the indoor unit 11, the outdoor unit 13 proceeds to step S12. The following description will be made on the assumption that the operation command here is a cooling operation command.

(Step S12)
The outdoor unit 13 starts the operation of the compressor 21. For example, when the outdoor unit 13 starts the operation of the compressor 21, the air conditioner 1 enters a state of starting the cooling operation.

(Step S13)
The outdoor unit 13 determines whether or not a certain time has elapsed since the operation of the compressor 21 was started. The outdoor unit 13 proceeds to step S14 when a predetermined time has elapsed since the operation of the compressor 21 was started. On the other hand, the outdoor unit 13 returns to step S13, when fixed time has not passed since the operation of the compressor 21 was started.

  That is, the outdoor unit 13 shifts the refrigeration cycle state of the refrigerant circuit configured in the air conditioner 1 to a stable state by not shifting to the next process until a predetermined time has elapsed. In addition, although it does not specifically limit with fixed time, For example, time for several minutes is set. Note that the certain time here is set based on the overall system performance of the air conditioner 1.

(Step S14)
The outdoor unit 13 derives the refrigerant circulation amount Gr of the refrigerant circuit. For example, the outdoor unit 13 derives the refrigerant circulation amount Gr based on the equation (1) described above.

(Step S15)
The outdoor unit 13 derives a low pressure loss ΔPs. Specifically, the outdoor unit 13 obtains the low pressure loss ΔPs by performing an operation of subtracting the suction pressure Ps from the evaporation pressure Pe.

(Step S16)
The outdoor unit 13 obtains the gas side extension pipe length based on the correlation among the refrigerant circulation amount Gr, the low pressure loss ΔPs, and the gas side extension pipe length.

(Step S17)
The outdoor unit 13 derives the liquid side extended pipe length from the gas side extended pipe length.

(Step S18)
The outdoor unit 13 derives the pressure loss ΔPd of the liquid side extension pipe 15.

(Step S19)
The outdoor unit 13 obtains the pressure Pm before the first electronic expansion valve 27 based on the pressure loss ΔPd and the condenser pressure Pd. For example, the outdoor unit 13 calculates the pressure Pm before the first electronic expansion valve 27 by performing a calculation of subtracting the pressure loss ΔPd from the condenser pressure Pd.

(Step S20)
The outdoor unit 13 derives a liquid side saturation temperature Tm corresponding to the pressure Pm before the first electronic expansion valve 27. For example, the outdoor unit 13 obtains the liquid side saturation temperature Tm by converting the pressure Pm before the first electronic expansion valve 27 into a saturated pressure.

  The method for converting the saturation pressure is not particularly limited. For example, a derivation formula may be set in the outdoor unit 13 in advance. Further, for example, a mapping table for converting the saturated pressure may be set in the outdoor unit 13. In this case, even if the corresponding parameter does not exist directly, it may be obtained by the outdoor unit 13 performing interpolation processing or the like.

(Step S21)
The outdoor unit 13 derives a liquid side saturation temperature Tc corresponding to the condenser pressure Pd. For example, the outdoor unit 13 obtains the liquid side saturation temperature Tc by converting the condenser pressure Pd into the saturation pressure. As described above, the method for converting the saturation pressure is not particularly limited.

(Step S22)
The outdoor unit 13 derives a subcooling amount SCm1 necessary for maintaining the single-phase refrigerant before the first electronic expansion valve 27. For example, the outdoor unit 13 obtains the subcool amount SCm1 by performing an operation of subtracting the liquid side saturation temperature Tm from the liquid side saturation temperature Tc.

(Step S23)
The outdoor unit 13 detects the outlet temperature Tout of the outdoor heat exchanger 25. For example, the outdoor unit 13 detects the outlet temperature Tout of the outdoor heat exchanger 25 by acquiring the detection result of the liquid first thermistor 45.

(Step S24)
The outdoor unit 13 derives the subcooling amount SC1 that is actually secured by the outdoor heat exchanger 25. For example, the outdoor unit 13 calculates the subcooling amount SC1 by performing a calculation of subtracting the outlet temperature Tout of the outdoor heat exchanger 25 from the liquid side saturation temperature Tc.

(Step S25)
The outdoor unit 13 determines whether SC1> SCm1 + β1 or SC1 <SCm1-α1. If SC1> SCm1 + β1 or SC1 <SCm1−α1, the outdoor unit 13 proceeds to step S26. On the other hand, if SC1> SCm1 + β1 or SC1 <SCm1−α1, the outdoor unit 13 proceeds to step S27.

(Step S26)
The outdoor unit 13 updates the opening degree of the first electronic expansion valve 27. Specifically, when SC1> SCm1 + β1, the outdoor unit control device 51 issues an opening degree update command for updating the opening degree of the first electronic expansion valve 27 to be more open compared to the current time. To supply. When SC1 <SCm1-α1, the outdoor unit controller 51 supplies the first electronic expansion valve 27 with an opening degree update command for updating the opening degree of the first electronic expansion valve 27 to be closed compared to the present time. .

(Step S27)
The outdoor unit 13 determines whether or not the operation command for the indoor unit 11 is continued. If the operation command for the indoor unit 11 is continued, the outdoor unit 13 proceeds to step S28. On the other hand, the outdoor unit 13 ends the process when the operation command for the indoor unit 11 is not continued.

(Step S28)
The outdoor unit 13 holds the opening degree of the first electronic expansion valve 27 for a predetermined time a1.

(Step S29)
The outdoor unit 13 determines whether or not a certain period of time b1 has elapsed since the opening degree of the first electronic expansion valve 27 is updated. Outdoor unit 13 returns to Step S14, when fixed time b1 passes since the opening degree of the 1st electronic expansion valve 27 was updated. On the other hand, the outdoor unit 13 returns to step S25, when the fixed time b1 has not passed since the opening degree of the 1st electronic expansion valve 27 was updated.

  In addition, although the control main body of said process was demonstrated as the outdoor unit 13, it is not specifically limited to this. For example, the indoor unit 11 may be the controlling entity. In this case, the process of step S11 becomes unnecessary. Further, an external device (for example, a portable terminal) or an external system (for example, HEMS) (not shown) may be the control entity. In this case, an external device (not shown) or an external system (not shown) and the air conditioner 1 may perform the above-described processing by performing various mutual communications by wire or wireless.

<Effect of the invention>
From the above explanation, the air conditioner 1 has the outlet side of the outdoor unit 13 calculated based on the correlation between the low pressure loss ΔPs, the gas extension pipe length corresponding to the liquid side extension pipe length, and the refrigerant circulation amount Gr. It is possible to appropriately control the subcool amount SC1. Therefore, the air conditioner 1 can adjust the subcool amount SC1 on the outlet side of the outdoor unit 13 without excessively increasing without adding a sensor for detecting the pressure loss amount of the liquid side extension pipe 15. The refrigerant can be returned to the indoor unit 11 while being in the liquid single phase.

  Therefore, the air conditioner 1 can appropriately control the subcooling amount SC1 on the outlet side of the outdoor unit 13 according to the length of the liquid side extension pipe 15 while avoiding an increase in cost. Therefore, the air conditioner 1 can avoid an increase in the amount of necessary refrigerant while preventing a decrease in operating efficiency related to cooling.

  In other words, since the air conditioner 1 does not require installation of a sensor such as a pressure sensor in front of the first electronic expansion valve 27, an increase in cost can be avoided. Therefore, the air conditioner 1 can realize an inexpensive circuit configuration.

  Further, the air conditioner 1 has a correlation between the low-pressure pressure loss ΔPs, the refrigerant circulation amount Gr, and the gas-side extension pipe length, depending on the length of the liquid-side extension pipe 15. The subcool amount SC1 is controlled so as to follow the target subcool amount SCm1 on the outlet side of the outdoor unit 13. Therefore, the air conditioner 1 can prevent a decrease in operating efficiency related to cooling, and can avoid an increase in the amount of necessary refrigerant.

  As described above, in the first embodiment, the compressor 21, which compresses and discharges the refrigerant, the outdoor heat exchanger 25, the first electronic expansion valve 27, the indoor heat exchanger 29, the compressor 21, and the outdoor heat. The outdoor unit 13 provided with the exchanger 25, the indoor unit 11 provided with the indoor heat exchanger 29, the gas side extension pipe 17, the liquid side extension pipe 15, and the evaporation temperature Te of the indoor heat exchanger 29 are detected. An indoor heat exchanger thermistor 49, a low-pressure sensor 43 that detects the suction pressure Ps on the suction side of the compressor 21, and an outdoor unit controller 51 that controls the opening degree of the first electronic expansion valve 27. The outdoor unit 13 and the indoor unit 11 are connected via the side extension pipe 17 and the liquid side extension pipe 15, and the compressor 21, the outdoor heat exchanger 25, the first electronic expansion valve 27, and the indoor heat exchanger are connected. 29 are connected in order and cold In the air conditioner 1 in which a circuit is formed, the outdoor unit controller 51 corresponds to the low pressure loss ΔPs corresponding to the pressure loss of the gas side extension pipe 17 and the length of the gas side extension pipe 17. The indoor heat exchanger thermistor is assumed to have a correlation between the gas side extension pipe length and the refrigerant circulation amount Gr corresponding to the refrigerant amount circulating in the refrigerant circuit, and corresponding to the low pressure loss ΔPs. Based on the detection results of 49 and the low-pressure sensor 43, a low-pressure pressure loss ΔPs corresponding to the pressure loss on the low-pressure side of the refrigerant circuit is obtained, and the refrigerant circulation corresponding to the driving of the compressor 21 is assumed to correspond to the refrigerant circulation amount Gr. The amount Gr is obtained, the gas side extension pipe length is obtained based on the low pressure loss ΔPs, the refrigerant circulation amount Gr, and the correlation, and the liquid side extension corresponding to the length of the liquid side extension pipe 15 is calculated from the gas side extension pipe length. Based on the pressure loss ΔPd of the liquid side extension pipe 15 and the condenser pressure Pd of the outdoor heat exchanger 25 obtained according to the liquid side extension pipe length, the long pipe length is obtained. The front pressure Pm is obtained, the liquid side saturation temperature Tm corresponding to the pressure Pm is obtained, the liquid side saturation temperature Tc of the refrigerant flowing through the outdoor heat exchanger 25 is obtained, and the liquid side saturation temperature Tm and the liquid side saturation temperature Tc are obtained. The subcool amount SCm1 is derived as a subcool amount that is a target on the outlet side of the outdoor heat exchanger 25 and maintains the liquid phase state of the refrigerant flowing into the first electronic expansion valve 27, based on What controls the opening degree of the 1st electronic expansion valve 27 according to SCm1 is comprised.

  Due to the above configuration, the air conditioner 1 according to Embodiment 1 can avoid an increase in the amount of necessary refrigerant while preventing a decrease in operating efficiency related to cooling.

  In the first embodiment, the outdoor unit controller 51 controls the opening degree of the first electronic expansion valve 27 based on the subcooling amount SCm1, thereby setting the outlet temperature Tout of the outdoor heat exchanger 25. adjust.

  In the first embodiment, the indoor unit 11 includes the first electronic expansion valve 27.

  In the first embodiment, the outdoor unit controller 51 obtains the refrigerant circulation amount Gr based on the stroke volume, operating frequency, intake gas density, and volumetric efficiency corresponding to the driving of the compressor 21. The evaporation pressure Pe of the indoor heat exchanger 29 is obtained based on the evaporation temperature Te, the low pressure loss ΔPs is obtained based on the evaporation pressure Pe and the suction pressure Ps of the compressor 21, and the outdoor heat exchanger 25 The subcool amount SC1 that is the subcool amount on the outlet side is adjusted within the range of the subcool amount SCm1.

  Therefore, the air conditioner 1 can avoid an increase in the necessary amount of refrigerant while remarkably preventing a decrease in operating efficiency related to cooling.

Embodiment 2. FIG.
<Summary of invention>
The difference from the first embodiment is that the outdoor unit 13 further includes a double pipe heat exchanger 61 and a second electronic expansion valve 63. The air conditioner 1 according to the second embodiment uses the double pipe heat exchanger 61 and the second electronic expansion valve 63 so that the gas side extension pipe 17 and the liquid side extension pipe 15 are the same as those in the first embodiment. Even if the length is further increased, the subcool amount SC2 on the outlet side of the outdoor unit 13 is secured. In the following description, the cooling operation is assumed as in the case of the first embodiment.

<Structure of the invention>
FIG. 6 is a diagram illustrating an example of a refrigerant circuit configuration of the air conditioner 1 according to Embodiment 2 of the present invention. As shown in FIG. 6, the outdoor unit 13 further includes a double pipe heat exchanger 61, a second electronic expansion valve 63, an accumulator 65, and a liquid pipe side second thermistor 71.

  The double pipe heat exchanger 61 is provided between the outdoor heat exchanger 25 and the liquid side extension pipe connection valve 37, and exchanges heat between the high pressure side refrigerant and the low pressure side refrigerant. The double pipe heat exchanger 61 further increases the subcooling amount SC2 of the condensed refrigerant by the heat exchange between the high pressure side refrigerant and the low pressure side refrigerant. That is, the double pipe heat exchanger 61 is not particularly limited as long as it can exchange heat between refrigerants.

  The second electronic expansion valve 63 is provided between the double pipe heat exchanger 61 and the liquid side extension pipe connection valve 37, and adjusts the flow rate of the low-pressure side refrigerant flowing through the double pipe heat exchanger 61. . The second electronic expansion valve 63 is directly controlled by the outdoor unit controller 51. The second electronic expansion valve 63 may be indirectly controlled by the indoor unit controller 53 via the outdoor unit controller 51.

  The accumulator 65 has a junction branch point between the low-pressure refrigerant pipe through which the low-pressure side refrigerant of the double pipe heat exchanger 61 flows and the high-pressure refrigerant pipe through which the high-pressure side refrigerant of the double pipe heat exchanger 61 on the main stream side flows. The four-way valve 23 and the suction side of the compressor 21 are provided. The liquid pipe side second thermistor 71 is provided between the outlet side of the high pressure refrigerant pipe through which the high pressure side refrigerant of the double pipe heat exchanger 61 circulates and the liquid side extension pipe connection valve 37, The outlet temperature Thout is detected, and the detection result is supplied to the outdoor unit controller 51.

  Next, specific functions of the double tube heat exchanger 61 and the second electronic expansion valve 63 will be described. During the cooling operation, the refrigerant passes through the outdoor heat exchanger 25 and then goes to the liquid side extension pipe connection valve 37 that is an outlet of the liquid refrigerant in the outdoor unit 13. At that time, the refrigerant branches after passing through the double pipe heat exchanger 61 provided on the way to the liquid side extension pipe connection valve 37. One of the branched refrigerants is depressurized by the second electronic expansion valve 63, becomes a low-pressure side refrigerant, passes through the double pipe heat exchanger 61 again, and moves toward the accumulator 65.

  At this time, the refrigerant flowing into the double-pipe heat exchanger 61 after passing through the outdoor heat exchanger 25 is a high-pressure side refrigerant, and heat exchange is performed with the low-pressure side refrigerant. By this function, the high-pressure side refrigerant flowing into the double pipe heat exchanger 61 is cooled, and the subcool amount SC2 further increases from the state when it exits the outlet side of the outdoor heat exchanger 25. Therefore, even if the gas-side extension pipe 17 and the liquid-side extension pipe 15 are longer than those in the first embodiment, the refrigerant can flow through the indoor unit 11 while ensuring the subcool.

  The operation of the second electronic expansion valve 63 that generates the low-pressure side refrigerant in the double-tube heat exchanger 61 will be described. The second electronic expansion valve 63 has a subcooling amount SC2 that is secured on the outlet side of the high-pressure refrigerant pipe of the double pipe heat exchanger 61 during the cooling operation. The opening / closing operation is performed so as to approach the subcool amount SCm2. The subcool amount SC2 is derived by subtracting the outlet temperature Thout of the high-pressure refrigerant pipe of the double pipe heat exchanger 61 from the liquid side saturation temperature Tc. The subcool amount SCm2 is derived by subtracting the liquid side saturation temperature Tm from the liquid side saturation temperature Tc.

  That is, the outdoor unit controller 51 determines the opening degree of the second electronic expansion valve 63 based on the difference between the subcool amount SCm2 and the subcool amount SC2, and operates the second electronic expansion valve 63.

  Strictly speaking, the pressure on the inlet side of the high-pressure refrigerant pipe of the double-tube heat exchanger 61 is compared with the condenser pressure Pd due to the effect of pressure loss generated in the refrigerant path from the outlet side of the outdoor heat exchanger 25. Will be slightly lower. Therefore, when it is assumed that the pressure loss is large between the outdoor heat exchanger 25 and the double-pipe heat exchanger 61, the subcool amount SC2 is derived after negatively correcting the liquid side saturation temperature Tc. May be.

  In other words, the second electronic expansion valve 63 adjusts the flow rate of the low-pressure side refrigerant, and the subcool amount SC2 on the outlet side of the high-pressure refrigerant pipe of the double-pipe heat exchanger 61 becomes a target value, for example, the subcool amount SCm2. Open / close operation to approach. The subcool amount SCm2 can be derived in the same manner as in the method described in the first embodiment. For example, the subcool amount SCm2 can be derived using the pressure loss ΔPd generated in the liquid side extension pipe 15.

  Specifically, the second electronic expansion valve 63 sets the subcooling amount SC2 between the outlet side of the double pipe heat exchanger 61 and the front side of the liquid side extension pipe connection valve 37 to the target subcooling amount SCm2. Adjust to get closer. Therefore, the second electronic expansion valve 63 can avoid a shortage of gas in the intermediate pressure side flow path in the refrigerant circuit due to excessive flow of the refrigerant to the low pressure refrigerant pipe of the double pipe heat exchanger 61. By performing such an operation, the air conditioner 1 prevents a decrease in cooling capacity.

  FIG. 7 is a diagram illustrating an example of a functional configuration of the outdoor unit control device 51 according to Embodiment 2 of the present invention. As shown in FIG. 7, the pressure loss deriving unit 113 derives the downstream pressure Pout of the double pipe heat exchanger 61 in addition to the pressure loss ΔPd. The downstream pressure Pout is detected by the double pipe heat exchanger 61 detected by the liquid pipe side second thermistor 71 provided between the double pipe heat exchanger 61 and the liquid side extension pipe connection valve 37. It is derived by converting the outlet temperature Thout into a saturation pressure.

  That is, the downstream pressure Pout corresponds to the pressure on the outlet side of the high-pressure refrigerant pipe of the double pipe heat exchanger 61 described above. Since the pressure on the outlet side of the high pressure refrigerant pipe of the double pipe heat exchanger 61 is affected by the pressure reducing action of the second electronic expansion valve 63, the downstream pressure Pout is downstream of the double pipe heat exchanger 61. The pressure on the side is shown. The subcool amount deriving unit 119 derives the subcool amount SC2 and the subcool amount SCm2, and details thereof will be described later with reference to FIG.

  The second electronic expansion valve 63 corresponds to the second expansion valve in the present invention. Further, the subcool amount SC2 corresponds to the fourth subcool amount in the present invention. Further, the subcool amount SCm2 corresponds to the third subcool amount in the present invention. The double pipe heat exchanger 61 corresponds to the inter-refrigerant heat exchanger in the present invention.

<Principle of the invention>
FIG. 8 is a diagram illustrating an example of a Mollier diagram corresponding to the refrigerant circuit of the air conditioner 1 according to Embodiment 2 of the present invention. As shown in FIG. 8, the pressure Pm before the first electronic expansion valve 27 subtracts the downstream pressure Pout of the double pipe heat exchanger 61 and the pressure loss ΔPd generated in the liquid side extension pipe 15 from the condenser pressure Pd. To be derived. And liquid side saturation temperature Tm is calculated | required by converting pressure Pm into saturation pressure.

  Therefore, the subcooling amount SC2 determined by the difference between the outlet temperature Thout of the double tube heat exchanger 61 and the liquid side saturation temperature Tc is determined by the difference between the liquid side saturation temperature Tm and the liquid side saturation temperature Tc. If adjusted within the range of the subcool amount SCm2, the refrigerant on the upstream side of the first electronic expansion valve 27 is maintained in a liquid phase single phase.

<Operation of the Invention>
FIG. 9 is a flowchart for explaining a control example of the air conditioner 1 according to Embodiment 2 of the present invention. In the following description of the operation, it is assumed that the outdoor unit 13 in which the outdoor unit control device 51 is incorporated is the controlling entity.

(Step S41)
The outdoor unit 13 determines whether or not an operation command has arrived from the indoor unit 11. When the outdoor unit 13 does not receive the operation command from the indoor unit 11, the outdoor unit 13 returns to step S41. On the other hand, when the operation command arrives from the indoor unit 11, the outdoor unit 13 proceeds to step S42. The following description will be made on the assumption that the operation command here is a cooling operation command.

(Step S42)
The outdoor unit 13 starts the operation of the compressor 21. For example, when the outdoor unit 13 starts the operation of the compressor 21, the air conditioner 1 enters a state of starting the cooling operation.

(Step S43)
The outdoor unit 13 determines whether or not a certain time has elapsed since the operation of the compressor 21 was started. The outdoor unit 13 proceeds to step S44 when a predetermined time has elapsed since the operation of the compressor 21 was started. On the other hand, the outdoor unit 13 returns to step S43, when fixed time has not passed since the operation of the compressor 21 was started.

  Here, the outdoor unit 13 shifts the refrigeration cycle state of the refrigerant circuit configured in the air conditioner 1 to a stable state by not shifting to the next process until a predetermined time elapses. In addition, although it does not specifically limit with fixed time, For example, time for several minutes is set.

(Step S44)
The outdoor unit 13 derives the refrigerant circulation amount Gr of the refrigerant circuit. For example, the outdoor unit 13 derives the refrigerant circulation amount Gr based on the equation (1) described above.

(Step S45)
The outdoor unit 13 derives a low pressure loss ΔPs. Specifically, the outdoor unit 13 obtains the low pressure loss ΔPs by performing an operation of subtracting the suction pressure Ps from the evaporation pressure Pe.

(Step S46)
The outdoor unit 13 obtains the gas side extension pipe length based on the correlation among the refrigerant circulation amount Gr, the low pressure loss ΔPs, and the gas side extension pipe length.

(Step S47)
The outdoor unit 13 derives the liquid side extended pipe length from the gas side extended pipe length.

(Step S48)
The outdoor unit 13 derives the pressure loss ΔPd of the liquid side extension pipe 15.

(Step S49)
The outdoor unit 13 detects the outlet temperature Thout of the double pipe heat exchanger 61. For example, the outdoor unit 13 detects the outlet temperature Thout of the double pipe heat exchanger 61 by acquiring the detection result of the liquid pipe side second thermistor 71.

(Step S50)
The outdoor unit 13 derives the downstream pressure Pout of the double pipe heat exchanger 61 from the outlet temperature Thout.

(Step S51)
The outdoor unit 13 obtains the pressure Pm before the first electronic expansion valve 27 based on the pressure loss ΔPd, the condenser pressure Pd, and the downstream pressure Pout of the double pipe heat exchanger 61. For example, the outdoor unit 13 calculates the pressure Pm before the first electronic expansion valve 27 by performing a calculation of subtracting the pressure loss ΔPd and the downstream pressure Pout from the condenser pressure Pd.

(Step S52)
The outdoor unit 13 derives a liquid side saturation temperature Tm corresponding to the pressure Pm before the first electronic expansion valve 27. For example, the outdoor unit 13 obtains the liquid side saturation temperature Tm by converting the pressure Pm before the first electronic expansion valve 27 into a saturated pressure.

  The method for converting the saturation pressure is not particularly limited. For example, a derivation formula may be set in the outdoor unit 13 in advance. Further, for example, a mapping table for converting the saturated pressure may be set in the outdoor unit 13. In this case, even if the corresponding parameter does not exist directly, it may be obtained by the outdoor unit 13 performing interpolation processing or the like.

(Step S53)
The outdoor unit 13 derives a liquid side saturation temperature Tc corresponding to the condenser pressure Pd. For example, the outdoor unit 13 obtains the liquid side saturation temperature Tc by converting the condenser pressure Pd into the saturation pressure. As described above, the method for converting the saturation pressure is not particularly limited.

(Step S54)
The outdoor unit 13 derives a subcooling amount SCm2 necessary for maintaining the single-phase refrigerant before the first electronic expansion valve 27. For example, the outdoor unit 13 obtains the subcool amount SCm2 by performing an operation of subtracting the liquid side saturation temperature Tm from the liquid side saturation temperature Tc.

(Step S55)
The outdoor unit 13 derives the subcooling amount SC2 that is actually secured by the double tube heat exchanger 61. For example, the outdoor unit 13 obtains the subcooling amount SC2 by performing a calculation of subtracting the outlet temperature Thout of the double pipe heat exchanger 61 from the liquid side saturation temperature Tc.

(Step S56)
The outdoor unit 13 determines whether SC2> SCm2 + β2 or SC2 <SCm2-α2. The outdoor unit 13 proceeds to step S57 when SC2> SCm2 + β2 or SC2 <SCm2-α2. On the other hand, if SC2> SCm2 + β2 or SC2 <SCm2-α2, the outdoor unit 13 proceeds to step S58. Α2 and β2 are arbitrary constants for defining the stable range of the subcooling amount SC2, similarly to α1 and β1.

(Step S57)
The outdoor unit 13 updates the opening degree of the second electronic expansion valve 63. Specifically, when SC2> SCm2 + β2, the outdoor unit control device 51 issues an opening degree update command for updating the opening degree of the second electronic expansion valve 63 to be more open than at the present time. To supply. When SC2 <SCm2-α2, the outdoor unit control device 51 supplies the second electronic expansion valve 63 with an opening degree update command for updating the opening degree of the second electronic expansion valve 63 to be closed compared to the present time. .

(Step S58)
The outdoor unit 13 determines whether or not the operation command for the indoor unit 11 is continued. If the operation command for the indoor unit 11 is continued, the outdoor unit 13 proceeds to step S59. On the other hand, the outdoor unit 13 ends the process when the operation command for the indoor unit 11 is not continued.

(Step S59)
The outdoor unit 13 holds the opening degree of the second electronic expansion valve 63 for a predetermined time a2.

(Step S60)
The outdoor unit 13 determines whether or not a predetermined time b2 has elapsed since the opening degree of the second electronic expansion valve 63 was updated. Outdoor unit 13 returns to Step S44, when fixed time b2 has passed since the opening degree of the 2nd electronic expansion valve 63 was updated. On the other hand, the outdoor unit 13 returns to step S56, when the fixed time b2 has not passed since the opening degree of the 2nd electronic expansion valve 63 was updated. Here, in consideration of the stability of the refrigerant circuit, the timer unit 125 is set to satisfy a2 <b2.

  In addition, although the control main body of said process was demonstrated as the outdoor unit 13, it is not specifically limited to this. For example, the indoor unit 11 may be the controlling entity. In this case, the process of step S41 becomes unnecessary. Further, an external device (for example, a portable terminal) or an external system (for example, HEMS) (not shown) may be the control entity. In this case, an external device (not shown) or an external system (not shown) and the air conditioner 1 may perform the above-described processing by performing various mutual communications by wire or wireless.

<Effect of the invention>
From the above description, the air conditioner 1 according to Embodiment 2 can further increase the subcooling amount SC2 of the condensed refrigerant by using the double tube heat exchanger 61. Therefore, the air conditioner 1 according to Embodiment 2 can ensure the subcooling amount SC2 corresponding to the longer gas extension pipe length and the longer liquid side extension pipe length. Therefore, also in the second embodiment, the air conditioner 1 can avoid an increase in the necessary refrigerant amount while preventing a decrease in operating efficiency related to cooling.

  As described above, in the second embodiment, the compressor 21 that compresses and discharges the refrigerant, the outdoor heat exchanger 25, the first electronic expansion valve 27, the indoor heat exchanger 29, the compressor 21, and the outdoor heat exchange. The indoor unit 11 provided with the unit 25, the indoor unit 11 provided with the indoor heat exchanger 29, the gas side extension pipe 17, the liquid side extension pipe 15, and the room for detecting the evaporation temperature Te of the indoor heat exchanger 29. A heat exchanger thermistor 49, a low-pressure sensor 43 that detects the suction pressure Ps on the suction side of the compressor 21, and an outdoor unit controller 51 that controls the opening degree of the first electronic expansion valve 27. The outdoor unit 13 and the indoor unit 11 are connected via the extension pipe 17 and the liquid side extension pipe 15, and the compressor 21, the outdoor heat exchanger 25, the first electronic expansion valve 27, and the indoor heat exchanger 29 are connected. Are connected in order to refrigerant In the air conditioner 1 in which a path is formed, the indoor unit 11 includes a first electronic expansion valve 27, and the outdoor unit 13 includes a gas side extension pipe connection valve 35 that connects the gas side extension pipe 17, and The liquid side extension pipe connection valve 37 for connecting the liquid side extension pipe 15 and the outdoor heat exchanger 25 and the liquid side extension pipe connection valve 37 are provided to heat the high pressure side refrigerant and the low pressure side refrigerant. A double pipe heat exchanger 61 to be exchanged, a second electronic expansion valve 63 provided between the double pipe heat exchanger 61 and the liquid side extension pipe connection valve 37 to adjust the flow rate of the low pressure side refrigerant; The outdoor unit control device 51 controls the opening degree of the second electronic expansion valve 63, and includes a low pressure loss ΔPs corresponding to the pressure loss of the gas side extension pipe 17 and the gas side extension pipe 17. Gas side extension pipe length equivalent to the length of The correlation between the refrigerant circulation amount Gr corresponding to the refrigerant amount circulating in the circuit is set, and the detection result of the indoor heat exchanger thermistor 49 and the low pressure sensor 43 is assumed to correspond to the low pressure loss ΔPs. The low-pressure pressure loss ΔPs corresponding to the pressure loss on the low-pressure side of the refrigerant circuit is obtained, the refrigerant circulation amount Gr corresponding to the driving of the compressor 21 is obtained as the refrigerant circulation amount Gr, and the low-pressure pressure loss is obtained. Based on ΔPs, the refrigerant circulation amount Gr, and the correlation, the gas side extension pipe length is obtained, the liquid side extension pipe length corresponding to the length of the liquid side extension pipe 15 is obtained from the gas side extension pipe length, and the double pipe The downstream pressure Pout of the refrigerant flowing out of the heat exchanger 61 is obtained, the pressure loss ΔPd of the liquid side extension pipe 15 obtained according to the liquid side extension pipe length, the downstream pressure Pout, and the condenser of the outdoor heat exchanger 25. Pressure Based on Pd, the pressure Pm before the first electronic expansion valve 27 is obtained, the liquid side saturation temperature Tm corresponding to the pressure Pm is obtained, the liquid side saturation temperature Tc of the refrigerant flowing through the outdoor heat exchanger 25 is obtained, Based on the liquid-side saturation temperature Tm and the liquid-side saturation temperature Tc, the target on the outlet side of the double-tube heat exchanger 61 and the liquid phase state of the refrigerant flowing into the first electronic expansion valve 27 is maintained. The subcool amount SCm2 is derived as the subcool amount to be performed, and the outlet temperature Thout of the double-tube heat exchanger 61 is adjusted by controlling the opening degree of the second electronic expansion valve 63 based on the subcool amount SCm2.

  In the second embodiment, the outdoor unit control device 51 obtains the refrigerant circulation amount Gr based on the stroke volume, the operating frequency, the suction gas density, and the volume efficiency corresponding to the driving of the compressor 21. The evaporation pressure Pe of the indoor heat exchanger 29 is obtained based on the evaporation temperature Te, the low pressure loss ΔPs is obtained based on the evaporation pressure Pe and the suction pressure Ps of the compressor 21, and the double pipe heat exchanger The subcool amount SC2, which is the subcool amount on the 61 outlet side, is adjusted within the range of the subcool amount SCm2.

  Therefore, the air conditioner 1 can avoid an increase in the necessary amount of refrigerant while remarkably preventing a decrease in operating efficiency related to cooling.

Embodiment 3 FIG.
<Summary of invention>
The difference between the first embodiment and the second embodiment is that a plurality of indoor units 11 described in the first embodiment and the second embodiment are provided, and the plurality of indoor units 11 are the outdoor units described in the first embodiment. The air conditioner 1 is configured by being connected to the unit 13.

  Here, in the multi-type refrigerant circuit configuration in which the plurality of indoor units 11 are connected to the outdoor unit 13, the lengths of the gas side extension pipe 17 and the liquid side extension pipe 15 are different. Therefore, the air conditioner 1 according to Embodiment 3 is an indoor unit having a maximum liquid-side extension pipe length corresponding to the largest liquid-side extension pipe 15 among the plurality of liquid-side extension pipes 15. The point which is set as the necessary target subcool amount SCm1 corresponding to 11 will be described.

<Structure of the invention>
FIG. 10 is a diagram illustrating an example of a refrigerant circuit configuration of the air conditioner 1 according to Embodiment 3 of the present invention. As shown in FIG. 10, the indoor units 11_1 to 11_n are connected to the outdoor unit 13.

  Specifically, the indoor unit 11_1 is connected to the outdoor unit 13 through the gas side extension pipe 17_1 and the liquid side extension pipe 15_1. The indoor unit 11_2 is connected to the outdoor unit 13 through a gas side extension pipe 17_2 and a liquid side extension pipe 15_2. Similarly, each of the indoor units 11_3 to 11_n is connected to the outdoor unit 13 via each of the gas side extension pipes 17_3 to 17_n and the liquid side extension pipes 15_3 to 15_n.

  The indoor unit 11_1 includes a first electronic expansion valve 27_1, an indoor heat exchanger 29_1, an indoor blower 33_1, an indoor heat exchanger thermistor 49_1, and an indoor unit controller 53_1. Note that the indoor units 11_2 to 11_n have the same configuration as the indoor unit 11_1, and thus the description thereof is omitted.

  Note that the indoor units 11_1 to 11_n are referred to as indoor units 11 unless otherwise distinguished. Further, when the gas side extension pipes 17_1 to 17_n are not particularly distinguished, they are referred to as gas side extension pipes 17. In addition, the liquid side extension pipes 15_1 to 15_n are referred to as the liquid side extension pipes 15 unless particularly distinguished. The indoor heat exchangers 29_1 to 29_n are referred to as indoor heat exchangers 29 unless otherwise distinguished. The first electronic expansion valves 27 </ b> _ <b> 1 to 27 </ b> _n are referred to as first electronic expansion valves 27 when not particularly distinguished. Moreover, when not distinguishing indoor fan 33_1-33_n in particular, it calls the indoor fan 33. In addition, the indoor heat exchanger thermistors 49_1 to 49_n are referred to as indoor heat exchanger thermistors 49 unless particularly distinguished. In addition, when the indoor unit control devices 53_1 to 53_n are not particularly distinguished, they are referred to as indoor unit control devices 53.

  That is, FIG. 10 shows an example of the air conditioner 1 configured by connecting n indoor units 11 and outdoor units 13.

  In the multi-type refrigerant circuit configuration in which the indoor units 11_1 to 11_n are connected to the outdoor unit 13, among the gas-side refrigerant pipe length and the liquid-side refrigerant pipe length corresponding to each indoor unit 11, the subcooling amount corresponding to the longest one. If SCm1 is derived, a subcooling is ensured before the first electronic expansion valves 27 of all the indoor units 11. Therefore, the function of selecting the longest one among the plurality of gas side refrigerant pipe lengths will be described with reference to FIG.

  FIG. 11 is a diagram illustrating an example of a functional configuration of the outdoor unit control device 51 according to Embodiment 3 of the present invention. As shown in FIG. 11, the low-pressure pressure loss deriving unit 103 performs the calculation as described above based on the detection results of the indoor heat exchanger thermistors 49_1 to 49_n and the detection result of the low-pressure sensor 43. Thus, the low pressure loss ΔPs1 to ΔPsn is obtained. Then, the maximum value determination unit 131 determines and selects the largest value among them. Next, the air conditioner 1 obtains the maximum pressure loss amount from the selected one, and obtains the target subcool amount SCm1 based on the obtained maximum pressure loss amount.

  As shown in FIG. 11, the refrigerant circulation amount deriving unit 101 derives the refrigerant circulation amounts Gr <b> 1 to Grn flowing in the indoor units 11 in order to derive the pressure loss amount generated in the gas side extension pipe 17.

  For example, the refrigerant circulation amount deriving unit 101 uses various setting information such as volumes and capacity classes of the indoor heat exchangers 29_1 to 29_n of the indoor units 11_1 to 11_n held by the indoor unit controllers 53_1 to 53_n. The refrigerant circulation amounts Gr1 to Grn may be derived by determining the distribution ratio from all the refrigerant circulation amounts Gr. Further, as described above, the refrigerant circulation amount deriving unit 101 may obtain the refrigerant circulation amounts Gr <b> 1 to Grn by using a program that implements the equation (1), for example, the algorithm of the equation (1). .

<Operation of the Invention>
FIG. 12 is a flowchart for explaining a control example of the air conditioner 1 according to Embodiment 3 of the present invention. In the following description of the operation, it is assumed that the outdoor unit 13 in which the outdoor unit control device 51 is incorporated is the controlling entity.

(Step S71)
The outdoor unit 13 determines whether or not an operation command has arrived from any of the indoor units 11_1 to 11_n. When the operation command arrives from any of the indoor units 11_1 to 11_n, the outdoor unit 13 proceeds to step S72. On the other hand, when the operation command does not arrive from any of the indoor units 11_1 to 11_n, the outdoor unit 13 returns to step S71. The following description will be made on the assumption that the operation command here is a cooling operation command.

(Step S72)
The outdoor unit 13 starts the operation of the compressor 21.

(Step S73)
The outdoor unit 13 proceeds to step S74 when a predetermined time has elapsed since the operation of the compressor 21 was started. On the other hand, the outdoor unit 13 returns to step S73, when fixed time has not passed since the driving | operation of the compressor 21 was started.

(Step S74)
The outdoor unit 13 derives the refrigerant circulation amounts Gr <b> 1 to Grn of the indoor units 11. Specifically, the outdoor unit 13 derives the refrigerant circulation amount Gr1 corresponding to the indoor unit 11_1, derives the refrigerant circulation amount Gr2 corresponding to the indoor unit 11_2, and similarly, A refrigerant circulation amount Gr corresponding to the unit 11 is derived.

(Step S75)
The outdoor unit 13 derives the low pressure loss ΔPs of each indoor unit 11. Specifically, the outdoor unit 13 derives a low-pressure pressure loss ΔPs1 corresponding to the indoor unit 11_1, derives a low-pressure pressure loss ΔPs2 corresponding to the indoor unit 11_2, and similarly, until the nth unit, A low pressure loss ΔPs corresponding to the unit 11 is derived.

(Step S76)
The outdoor unit 13 selects the maximum low-pressure pressure loss among the low-pressure pressure losses ΔPs1 to ΔPsn.

(Step S77)
The outdoor unit 13 obtains the gas side extension pipe length based on the correlation between the refrigerant circulation amount Gr, the maximum low pressure loss and the gas side extension pipe length.

(Step S78)
The outdoor unit 13 derives the liquid side extended pipe length from the gas side extended pipe length.

(Step S79)
The outdoor unit 13 derives the maximum pressure loss ΔPd of the liquid side extension pipe 15. That is, since the outdoor unit 13 calculates | requires pressure loss (DELTA) Pd of the liquid side extension piping 15 corresponding to the largest low voltage | pressure pressure loss, what is calculated | required becomes the largest pressure loss (DELTA) Pd.

(Step S80)
The outdoor unit 13 obtains the lowest pressure Pm among the pressures Pm before the first electronic expansion valves 27_1 to 27_n based on the maximum pressure loss ΔPd and the condenser pressure Pd. That is, since the outdoor unit 13 calculates | requires the pressure Pm before the 1st electronic expansion valve 27 corresponding to the largest pressure loss (DELTA) Pd, what is calculated | required becomes the minimum pressure Pm.

(Step S81)
The outdoor unit 13 derives the lowest liquid side saturation temperature Tm corresponding to the lowest pressure Pm before the first electronic expansion valve 27. That is, since the outdoor unit 13 calculates | requires the liquid side saturation temperature Tm corresponding to the minimum pressure Pm, what is calculated | required becomes the minimum liquid side saturation temperature Tm. Therefore, the lowest liquid side saturation temperature Tm is the smallest value among the plurality of liquid side saturation temperatures Tm. Therefore, the subcool amount SCm1 obtained based on the liquid side saturation temperature Tm having the smallest value is the widest range, and the longest liquid side extension pipe 15 is taken into consideration.

(Step S82)
The outdoor unit 13 derives a liquid side saturation temperature Tc corresponding to the condenser pressure Pd.

(Step S83)
The outdoor unit 13 derives the subcooling amount SCm1 necessary for maintaining the single-phase refrigerant before the first electronic expansion valves 27_1 to 27_n. For example, the outdoor unit 13 derives the subcool amount SCm1 by subtracting the liquid side saturation temperature Tm from the liquid side saturation temperature Tc.

(Step S84)
The outdoor unit 13 detects the outlet temperature Tout of the outdoor heat exchanger 25.

(Step S85)
The outdoor unit 13 derives the subcooling amount SC1 that is actually secured by the outdoor heat exchanger 25. For example, the outdoor unit 13 derives the subcooling amount SC1 by subtracting the outlet temperature Tout of the outdoor heat exchanger 25 from the liquid side saturation temperature Tc.

(Step S86)
The outdoor unit 13 determines whether SC1> SCm1 + β1 or SC1 <SCm1-α1. If SC1> SCm1 + β1 or SC1 <SCm1−α1, the outdoor unit 13 proceeds to step S87. On the other hand, if SC1> SCm1 + β1 or SC1 <SCm1−α1, the outdoor unit 13 proceeds to step S88.

(Step S87)
The outdoor unit 13 updates the opening degree of the first electronic expansion valves 27_1 to 27_n.

(Step S88)
The outdoor unit 13 determines whether or not the operation command for the indoor unit 11 is continued. If the operation command for the indoor unit 11 is continued, the outdoor unit 13 proceeds to step S89. On the other hand, the outdoor unit 13 ends the process when the operation command for the indoor unit 11 is not continued.

(Step S89)
The outdoor unit 13 holds the opening degree of the first electronic expansion valves 27_1 to 27_n for a certain time a1.

(Step S90)
The outdoor unit 13 determines whether or not a certain period of time b1 has elapsed since the opening degree of the first electronic expansion valves 27_1 to 27_n has been updated. The outdoor unit 13 returns to step S74, when the fixed time b1 passes after updating the opening degree of the 1st electronic expansion valves 27_1-27_n. On the other hand, the outdoor unit 13 returns to step S86 when b1 does not elapse after the opening degree of the first electronic expansion valves 27_1 to 27_n is updated. Here, in consideration of the stability of the refrigerant circuit, the timer unit 125 is set to satisfy a1 <b1.

  In addition, although the control main body of said process was demonstrated as the outdoor unit 13, it is not specifically limited to this. For example, the indoor unit 11 may be the controlling entity. In this case, the process of step S71 becomes unnecessary. Further, an external device (for example, a portable terminal) or an external system (for example, HEMS) (not shown) may be the control entity. In this case, an external device (not shown) or an external system (not shown) and the air conditioner 1 may perform the above-described processing by performing various mutual communications by wire or wireless.

<Effect of the invention>
From the above description, the air conditioner 1 according to Embodiment 3 has a subcooling amount on the outlet side of the outdoor unit 13 according to the longest liquid side extension pipe 15 even when a plurality of indoor units 11 are provided. SC1 can be appropriately controlled. Therefore, the air conditioner 1 considers the difference between the gas side extension pipe length and the liquid side extension pipe length for each indoor unit 11, and based on the maximum gas side extension pipe length and the liquid side extension pipe length, the subcool amount SCm1. Can be derived.

  Therefore, the air conditioner 1 includes the first electronic expansion valve 27 so as to adjust the subcooling amount SC1 within the range of the subcooling amount SCm1 derived in consideration of the difference between the gas side extension piping length and the liquid side extension piping length. Since the opening degree is controlled, a subcooling before all the first electronic expansion valves 27 can be secured. Therefore, also in Embodiment 3, the air conditioner 1 can avoid an increase in the necessary refrigerant amount while preventing a decrease in operating efficiency related to cooling.

  As described above, in the third embodiment, a plurality of indoor units 11 connected to the outdoor unit 13 are provided.

  In the third embodiment, the outdoor unit controller 51 obtains the refrigerant circulation amount Gr based on the stroke volume, the operating frequency, the suction gas density, and the volume efficiency corresponding to the driving of the compressor 21. The evaporation pressure Pe of the indoor heat exchanger 29 is obtained for each indoor unit 11 based on the evaporation temperature Te, and the low pressure is calculated for each indoor unit 11 based on the evaporation pressure Pe and the suction pressure Ps of the compressor 21. The pressure loss ΔPs is obtained, the gas-side extension pipe length corresponding to the maximum of the low pressure loss ΔPs is obtained, and the subcool amount SC1 that is the subcool amount on the outlet side of the outdoor heat exchanger 25 is set within the range of the subcool amount SCm1. Adjust in.

  Therefore, the air conditioner 1 can avoid an increase in the necessary amount of refrigerant while remarkably preventing a decrease in operating efficiency related to cooling.

Embodiment 4 FIG.
<Summary of invention>
The difference from the first to third embodiments is that a plurality of indoor units 11 described in the first and second embodiments are provided, and the plurality of indoor units 11 are the outdoor units described in the second embodiment. The air conditioner 1 is configured by being connected to the unit 13.

  Here, in the multi-type refrigerant circuit configuration in which the plurality of indoor units 11 are connected to the outdoor unit 13, the lengths of the gas side extension pipe 17 and the liquid side extension pipe 15 are different. Therefore, the air conditioner 1 according to Embodiment 4 includes an indoor unit having a maximum liquid side extension pipe length corresponding to the largest liquid loss in the liquid side extension pipe 15 among the plurality of liquid side extension pipes 15. The subcool amount SCm2 that is a necessary target corresponding to 11 will be described.

<Structure of the invention>
FIG. 13 is a diagram illustrating an example of a refrigerant circuit configuration of the air conditioner 1 according to Embodiment 4 of the present invention. As shown in FIG. 13, the refrigerant circuit configuration of the air conditioner 1 according to the fourth embodiment is the same as that of the outdoor unit 13 described in the second embodiment, but the indoor unit 11 described in the first and second embodiments. In addition, as described in the third embodiment, a plurality of units are connected and formed. That is, the plurality of indoor units 11 are connected to the outdoor unit 13 including the double tube heat exchanger 61, the second electronic expansion valve 63, and the liquid tube side second thermistor 71.

  FIG. 14 is a diagram illustrating an example of a functional configuration of the outdoor unit control device 51 according to Embodiment 4 of the present invention. Although it is the same as the functional configuration described in the third embodiment, the subcool amount deriving unit 119 is different from the functional configuration described in the third embodiment in that the subcool amount SC2 and the subcool amount SCm2 are obtained.

<Operation of the Invention>
FIG. 15 is a flowchart for explaining a control example of the air conditioner 1 according to Embodiment 4 of the present invention. In the following description of the operation, it is assumed that the outdoor unit 13 in which the outdoor unit control device 51 is incorporated is the controlling entity.

(Step S101)
The outdoor unit 13 determines whether or not an operation command has arrived from any of the indoor units 11_1 to 11_n. When the operation command arrives from any of the indoor units 11_1 to 11_n, the outdoor unit 13 proceeds to step S102. On the other hand, the outdoor unit 13 returns to step S101 when the operation command does not reach from any of the indoor units 11_1 to 11_n. The following description will be made on the assumption that the operation command here is a cooling operation command.

(Step S102)
The outdoor unit 13 starts the operation of the compressor 21.

(Step S103)
The outdoor unit 13 proceeds to step S <b> 104 when a predetermined time has elapsed since the operation of the compressor 21 was started. On the other hand, the outdoor unit 13 returns to step S103, when fixed time has not passed since the operation of the compressor 21 was started.

(Step S104)
The outdoor unit 13 derives the refrigerant circulation amounts Gr <b> 1 to Grn of the indoor units 11. Specifically, the outdoor unit 13 derives the refrigerant circulation amount Gr1 corresponding to the indoor unit 11_1, derives the refrigerant circulation amount Gr2 corresponding to the indoor unit 11_2, and similarly, A refrigerant circulation amount Gr corresponding to the unit 11 is derived.

(Step S105)
The outdoor unit 13 derives the low pressure loss ΔPs of each indoor unit 11. Specifically, the outdoor unit 13 derives a low-pressure pressure loss ΔPs1 corresponding to the indoor unit 11_1, derives a low-pressure pressure loss ΔPs2 corresponding to the indoor unit 11_2, and similarly, until the nth unit, A low pressure loss ΔPs corresponding to the unit 11 is derived.

(Step S106)
The outdoor unit 13 selects the maximum low-pressure pressure loss among the low-pressure pressure losses ΔPs1 to ΔPsn.

(Step S107)
The outdoor unit 13 obtains the gas side extension pipe length based on the correlation between the refrigerant circulation amount Gr, the maximum low pressure loss and the gas side extension pipe length.

(Step S108)
The outdoor unit 13 derives the liquid side extended pipe length from the gas side extended pipe length.

(Step S109)
The outdoor unit 13 derives the maximum pressure loss ΔPd of the liquid side extension pipe 15. That is, since the outdoor unit 13 calculates | requires pressure loss (DELTA) Pd of the liquid side extension piping 15 corresponding to the largest low voltage | pressure pressure loss, what is calculated | required becomes the largest pressure loss (DELTA) Pd.

(Step S110)
The outdoor unit 13 detects the outlet temperature Thout of the double pipe heat exchanger 61.

(Step S111)
The outdoor unit 13 derives the downstream pressure Pout of the double pipe heat exchanger 61 from the outlet temperature Thout.

(Step S112)
The outdoor unit 13 has the lowest pressure Pm before the first electronic expansion valves 27_1 to 27_n based on the maximum pressure loss ΔPd, the condenser pressure Pd, and the downstream pressure Pout of the double pipe heat exchanger 61. Obtain the pressure Pm. That is, since the outdoor unit 13 calculates | requires the pressure Pm before the 1st electronic expansion valve 27 corresponding to the largest pressure loss (DELTA) Pd, what is calculated | required becomes the minimum pressure Pm.

(Step S113)
The outdoor unit 13 derives the lowest liquid side saturation temperature Tm corresponding to the lowest pressure Pm before the first electronic expansion valve 27. That is, since the outdoor unit 13 calculates | requires the liquid side saturation temperature Tm corresponding to the minimum pressure Pm, what is calculated | required becomes the minimum liquid side saturation temperature Tm. Therefore, the lowest liquid side saturation temperature Tm is the smallest value among the plurality of liquid side saturation temperatures Tm. Therefore, the subcool amount SCm2 obtained based on the liquid side saturation temperature Tm having the smallest value is the widest range, and the longest liquid side extension pipe 15 is taken into consideration.

(Step S114)
The outdoor unit 13 derives a liquid side saturation temperature Tc corresponding to the condenser pressure Pd.

(Step S115)
The outdoor unit 13 derives the subcooling amount SCm2 necessary for maintaining the single-phase refrigerant before the first electronic expansion valves 27_1 to 27_n. For example, the outdoor unit 13 derives the subcool amount SCm2 by subtracting the liquid side saturation temperature Tm from the liquid side saturation temperature Tc.

(Step S116)
The outdoor unit 13 derives the subcooling amount SC2 that is actually secured by the double tube heat exchanger 61. For example, the outdoor unit 13 derives the subcooling amount SC2 by subtracting the outlet temperature Thout of the double tube heat exchanger 61 from the liquid side saturation temperature Tc.

(Step S117)
The outdoor unit 13 determines whether SC2> SCm2 + β2 or SC2 <SCm2-α2. If SC2> SCm2 + β2 or SC2 <SCm2-α2, the outdoor unit 13 proceeds to step S118. On the other hand, if SC2> SCm2 + β2 or SC2 <SCm2-α2, the outdoor unit 13 proceeds to step S119.

(Step S118)
The outdoor unit 13 updates the opening degree of the second electronic expansion valve 63.

(Step S119)
The outdoor unit 13 determines whether or not the operation commands for the indoor units 11_1 to 11_n are continued. When the operation command for the indoor units 11_1 to 11_n is continued, the outdoor unit 13 proceeds to step S120. On the other hand, the outdoor unit 13 ends the process when the operation commands of the indoor units 11_1 to 11_n are not continued.

(Step S120)
The outdoor unit 13 holds the opening degree of the second electronic expansion valve 63 for a predetermined time a2.

(Step S121)
The outdoor unit 13 determines whether or not a predetermined time b2 has elapsed since the opening degree of the second electronic expansion valve 63 was updated. Outdoor unit 13 returns to Step S104, when fixed time b2 passes since the opening degree of the 2nd electronic expansion valve 63 was updated. On the other hand, the outdoor unit 13 returns to step S117 when b2 does not elapse after the opening degree of the second electronic expansion valve 63 is updated. Here, in consideration of the stability of the refrigerant circuit, the timer unit 125 is set to satisfy a2 <b2.

  In addition, although the control main body of said process was demonstrated as the outdoor unit 13, it is not specifically limited to this. For example, the indoor unit 11 may be the controlling entity. In this case, the process of step S101 becomes unnecessary. Further, an external device (for example, a portable terminal) or an external system (for example, HEMS) (not shown) may be the control entity. In this case, an external device (not shown) or an external system (not shown) and the air conditioner 1 may perform the above-described processing by performing various mutual communications by wire or wireless.

<Effect of the invention>
From the above description, the air conditioner 1 according to Embodiment 4 includes a plurality of indoor units 11, and the indoor unit 11 and the outdoor unit 13 are connected by the longer gas side extension pipe 17 and the longer liquid side extension pipe 15. Even when connected, the subcooling amount SC2 on the outlet side of the outdoor unit 13 can be appropriately controlled according to the longest liquid side extension pipe 15.

  Therefore, the air conditioner 1 considers the difference between the gas side extension pipe length and the liquid side extension pipe length for each indoor unit 11, and based on the maximum gas side extension pipe length and the liquid side extension pipe length, the subcool amount SCm2 Can be derived. Therefore, the air conditioner 1 includes the second electronic expansion valve 63 so as to adjust the subcool amount SC2 within the range of the subcool amount SCm2 derived in consideration of the difference between the gas side extension pipe length and the liquid side extension pipe length. Since the opening degree is controlled, a subcooling before all the first electronic expansion valves 27 can be secured. Therefore, also in Embodiment 4, the air conditioner 1 can avoid an increase in the necessary amount of refrigerant while preventing a decrease in operating efficiency related to cooling.

  As described above, in the fourth embodiment, a plurality of indoor units 11 connected to the outdoor unit 13 are provided.

  In the fourth embodiment, the outdoor unit controller 51 obtains the refrigerant circulation amount Gr based on the stroke volume, operating frequency, intake gas density, and volumetric efficiency corresponding to the driving of the compressor 21. The evaporation pressure Pe of the indoor heat exchanger 29 is obtained for each indoor unit 11 based on the evaporation temperature Te, and the low pressure is calculated for each indoor unit 11 based on the evaporation pressure Pe and the suction pressure Ps of the compressor 21. The pressure loss ΔPs is obtained, the gas-side extended pipe length corresponding to the largest one of the low-pressure pressure losses ΔPs is obtained, and the subcool amount SC2 that is the subcool amount on the outlet side of the double-pipe heat exchanger 61 is determined as the subcool amount SCm2. Adjust within the range.

  Therefore, the air conditioner 1 can avoid an increase in the necessary amount of refrigerant while remarkably preventing a decrease in operating efficiency related to cooling.

  DESCRIPTION OF SYMBOLS 1 Air conditioner 11, 11_1-11_n Indoor unit, 13 Outdoor unit, 15, 15_1-15_n Liquid side extension piping, 17, 17_1-17_n Gas side extension piping, 21 Compressor, 23 Four-way valve, 25 Outdoor heat exchanger 27, 27_1 to 27_n 1st electronic expansion valve, 29, 29_1 to 29_n indoor heat exchanger, 31 outdoor blower, 33, 33_1 to 33_n indoor blower, 35 gas side extension pipe connection valve, 37 liquid side extension pipe connection Valve, 41 High pressure sensor, 43 Low pressure sensor, 45 Liquid side first thermistor, 47 Outdoor heat exchanger intermediate temperature thermistor, 49, 49_1 to 49_n Indoor heat exchanger thermistor, 51 Control unit for outdoor unit, 53, 53_1 to 53_n Indoor Unit control unit, 61 Double tube heat exchanger, 63 Second electronic expansion Tightening valve, 65 accumulator, 71 liquid pipe side second thermistor, 101 refrigerant circulation amount deriving unit, 103 low pressure pressure loss deriving unit, 105 first mapping table, 107 gas side extension pipe length deriving unit, 109 second mapping table, 111 Liquid side extension pipe length deriving unit, 113 Pressure loss deriving unit, 115 Pressure calculating unit, 117 Liquid side saturation temperature deriving unit, 119 Subcooling amount deriving unit, 121 Subcooling amount determining unit, 123 Expansion valve opening degree controlling unit, 125 Timing unit 131 Maximum value determination unit.

Claims (10)

A compressor that compresses and discharges the refrigerant;
An outdoor heat exchanger,
A first expansion valve;
An indoor heat exchanger,
An outdoor unit comprising the compressor and the outdoor heat exchanger;
An indoor unit comprising the indoor heat exchanger;
Gas side extension piping,
Liquid side extension piping,
A thermistor for detecting the evaporation temperature of the indoor heat exchanger;
A sensor for detecting the suction pressure on the suction side of the compressor;
A control device for controlling the opening of the first expansion valve;
With
The outdoor unit and the indoor unit are connected via the gas side extension pipe and the liquid side extension pipe,
The air conditioner in which the compressor, the outdoor heat exchanger, the first expansion valve, and the indoor heat exchanger are connected in order to form a refrigerant circuit,
The control device includes:
The first pressure loss corresponding to the pressure loss of the gas side extension pipe, the first pipe length corresponding to the length of the gas side extension pipe, and the first refrigerant circulation amount corresponding to the refrigerant amount circulating in the refrigerant circuit And the correlation between
Based on the detection results of the thermistor and the sensor, the second pressure loss corresponding to the pressure loss on the low pressure side of the refrigerant circuit is determined as the first pressure loss.
As the one corresponding to the first refrigerant circulation amount, a second refrigerant circulation amount corresponding to the driving of the compressor is obtained,
Based on the second pressure loss, the second refrigerant circulation amount, and the correlation, the first pipe length is obtained.
Obtaining a second pipe length corresponding to the length of the liquid side extension pipe from the first pipe length;
Based on the third pressure loss of the liquid side extension pipe determined according to the second pipe length and the condensation pressure of the outdoor heat exchanger, the upstream pressure of the refrigerant flowing into the first expansion valve is determined. Seeking
Obtaining a first liquid side saturation temperature corresponding to the upstream pressure,
Determining the second liquid side saturation temperature of the refrigerant flowing through the outdoor heat exchanger;
Based on the first liquid side saturation temperature and the second liquid side saturation temperature, the liquid phase state of the refrigerant flowing into the first expansion valve is a target on the outlet side of the outdoor heat exchanger. The first subcool amount is derived as the subcool amount to be maintained,
An air conditioner that controls an opening degree of the first expansion valve in accordance with the first subcool amount. The control device includes:
The air conditioner according to claim 1, wherein an outlet temperature of the outdoor heat exchanger is adjusted by controlling an opening degree of the first expansion valve based on the first subcool amount. The indoor unit is
The air conditioner according to claim 2, comprising the first expansion valve. The control device includes:
Based on the stroke volume, operating frequency, intake gas density, and volumetric efficiency corresponding to the driving of the compressor, the second refrigerant circulation amount is obtained,
Based on the evaporation temperature, obtain the evaporation pressure of the indoor heat exchanger,
Based on the evaporation pressure and the suction pressure of the compressor, obtain the second pressure loss,
The air conditioner according to claim 3, wherein a second subcool amount, which is a subcool amount on the outlet side of the outdoor heat exchanger, is adjusted within a range of the first subcool amount. A compressor that compresses and discharges the refrigerant;
An outdoor heat exchanger,
A first expansion valve;
An indoor heat exchanger,
An outdoor unit comprising the compressor and the outdoor heat exchanger;
An indoor unit comprising the indoor heat exchanger;
Gas side extension piping,
Liquid side extension piping,
A thermistor for detecting the evaporation temperature of the indoor heat exchanger;
A sensor for detecting the suction pressure on the suction side of the compressor;
A control device for controlling the opening of the first expansion valve;
With
The outdoor unit and the indoor unit are connected via the gas side extension pipe and the liquid side extension pipe,
The air conditioner in which the compressor, the outdoor heat exchanger, the first expansion valve, and the indoor heat exchanger are connected in order to form a refrigerant circuit,
The indoor unit is
Comprising the first expansion valve;
The outdoor unit is
A first connection valve for connecting the gas side extension pipe;
A second connection valve for connecting the liquid side extension pipe;
An inter-refrigerant heat exchanger provided between the outdoor heat exchanger and the second connection valve, for exchanging heat between the high-pressure side refrigerant and the low-pressure side refrigerant;
A second expansion valve provided between the inter-refrigerant heat exchanger and the second connection valve, for adjusting a flow rate of the low-pressure refrigerant;
With
The control device includes:
Controlling the opening of the second expansion valve,
The first pressure loss corresponding to the pressure loss of the gas side extension pipe, the first pipe length corresponding to the length of the gas side extension pipe, and the first refrigerant circulation amount corresponding to the refrigerant amount circulating in the refrigerant circuit And the correlation between
Based on the detection results of the thermistor and the sensor, the second pressure loss corresponding to the pressure loss on the low pressure side of the refrigerant circuit is determined as the first pressure loss.
As the one corresponding to the first refrigerant circulation amount, a second refrigerant circulation amount corresponding to the driving of the compressor is obtained,
Based on the second pressure loss, the second refrigerant circulation amount, and the correlation, the first pipe length is obtained.
Obtaining a second pipe length corresponding to the length of the liquid side extension pipe from the first pipe length;
Determine the downstream pressure of the refrigerant that has flowed out of the inter-refrigerant heat exchanger,
Upstream of the refrigerant flowing into the first expansion valve based on the third pressure loss of the liquid side extension pipe determined according to the second pipe length, the downstream pressure, and the condensation pressure of the outdoor heat exchanger. Find the side pressure
Obtaining a first liquid side saturation temperature corresponding to the upstream pressure,
Determining the second liquid side saturation temperature of the refrigerant flowing through the outdoor heat exchanger;
Based on the first liquid side saturation temperature and the second liquid side saturation temperature, the liquid phase state of the refrigerant flowing into the first expansion valve, which is a target on the outlet side of the inter-refrigerant heat exchanger Deriving the third subcool amount as the subcool amount to maintain
An air conditioner that adjusts an outlet temperature of the inter-refrigerant heat exchanger by controlling an opening degree of the second expansion valve based on the third subcool amount. The control device includes:
Based on the stroke volume, operating frequency, intake gas density, and volumetric efficiency corresponding to the driving of the compressor, the second refrigerant circulation amount is obtained,
Based on the evaporation temperature, obtain the evaporation pressure of the indoor heat exchanger,
Based on the evaporation pressure and the suction pressure of the compressor, obtain the second pressure loss,
The air conditioner according to claim 5, wherein a fourth subcooling amount that is a subcooling amount on the outlet side of the inter-refrigerant heat exchanger is adjusted within a range of the third subcooling amount. The air conditioner according to claim 3, comprising a plurality of the indoor units connected to the outdoor unit. The control device includes:
Based on the stroke volume, operating frequency, intake gas density, and volumetric efficiency corresponding to the driving of the compressor, the second refrigerant circulation amount is obtained,
For each indoor unit, based on the evaporation temperature, determine the evaporation pressure of the indoor heat exchanger,
For each indoor unit, the second pressure loss is determined based on the evaporation pressure and the suction pressure of the compressor,
The first pipe length corresponding to the largest one of the second pressure losses is obtained,
The air conditioner according to claim 7, wherein a second subcool amount that is a subcool amount on the outlet side of the outdoor heat exchanger is adjusted within a range of the first subcool amount. The air conditioner according to claim 5, comprising a plurality of the indoor units connected to the outdoor unit. The control device includes:
Based on the stroke volume, operating frequency, intake gas density, and volumetric efficiency corresponding to the driving of the compressor, the second refrigerant circulation amount is obtained,
For each indoor unit, based on the evaporation temperature, determine the evaporation pressure of the indoor heat exchanger,
For each indoor unit, the second pressure loss is determined based on the evaporation pressure and the suction pressure of the compressor,
The first pipe length corresponding to the largest one of the second pressure losses is obtained,
The air conditioner according to claim 9, wherein a fourth subcool amount, which is a subcool amount on the outlet side of the inter-refrigerant heat exchanger, is adjusted within a range of the third subcool amount.

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