JP2020153603A

JP2020153603A - Air conditioner

Info

Publication number: JP2020153603A
Application number: JP2019053509A
Authority: JP
Inventors: 達哉松川; Tatsuya Matsukawa
Original assignee: Fujitsu General Ltd
Current assignee: Fujitsu General Ltd
Priority date: 2019-03-20
Filing date: 2019-03-20
Publication date: 2020-09-24

Abstract

To provide an air conditioner capable of properly adjusting an opening of an expansion valve even when a refrigerant passing through the expansion valve has a gas-liquid two phase state in an air conditioning operation.SOLUTION: A CPU 210 determines whether an actual refrigerant supercooling degree is a prescribed refrigerant supercooling degree SCd or less. When the actual supercooling degree SCp is a prescribed refrigerant supercooling degree SCd or less, the CPU 210 adds 1 to a present low SC number of times k, and determines whether the low SC number of times k is a prescribed number of times Kd or more, or not. When the low SC number of times k is a prescribed number of times Kd or more, the CPU 210 extracts a second pulse number P2 according to a discharge temperature difference ΔTd in reference to an expansion valve opening table 300, and adds the same to the expansion valve 24. On the other hand, when the actual refrigerant supercooling degree SCp is not less than the prescribed refrigerant supercooling degree SCd, the CPU 210 extracts a first pulse number P1 according to the discharge temperature difference ΔTd in reference to the expansion valve opening table 300, and adds the same to the expansion valve 24.SELECTED DRAWING: Figure 3

Description

本発明は空気調和機に関し、より詳細には、膨張弁の開度調整に関する。 The present invention relates to an air conditioner, and more specifically to adjusting the opening degree of an expansion valve.

空気調和機の運転時に、室内機における冷媒流量を調整する膨張弁は、冷媒回路を循環する冷媒の温度や圧力を含む冷媒の状態を表す状態量が目標値となるように、その開度が調整される。例えば、特許文献１には、冷房運転時に凝縮器として機能する室外熱交換器の冷媒出口側における冷媒過冷却度を上記状態量とし、冷媒過冷却度が目標冷媒過冷却度となるように、膨張弁の開度が調整されることが開示されている。また、圧縮機から吐出される冷媒の温度である吐出温度を上記状態量とし、吐出温度の目標吐出温度となるように、膨張弁の開度が調整される場合もある。 The opening of the expansion valve that adjusts the flow rate of the refrigerant in the indoor unit during operation of the air conditioner is set so that the target value is the state quantity that represents the state of the refrigerant including the temperature and pressure of the refrigerant circulating in the refrigerant circuit. It will be adjusted. For example, in Patent Document 1, the degree of refrigerant supercooling on the refrigerant outlet side of an outdoor heat exchanger that functions as a condenser during cooling operation is set to the above state quantity, and the degree of refrigerant supercooling is set to the target degree of refrigerant supercooling. It is disclosed that the opening degree of the expansion valve is adjusted. Further, the opening degree of the expansion valve may be adjusted so that the discharge temperature, which is the temperature of the refrigerant discharged from the compressor, is set as the above-mentioned state quantity and the target discharge temperature of the discharge temperature is reached.

膨張弁の開度は、膨張弁に備えられているパルスモータに、パルスモータの回転方向を示す極性と増減したい開度に対応したパルス数のパルスを含むパルス信号を与えることによって調整できる。膨張弁の開度を大きくしたいときは、正回転を示す極性（開度が大きくなる方向にパルスモータが回転する極性）と所定のパルス数のパルスを含むパルス信号が与えられ、膨張弁の開度を小さくしたいときは、逆回転を示す極性（開度が小さくなる方向にパルスモータが回転する極性）と所定のパルス数のパルスを含むパルス信号が与えられる。ここで、所定のパルス数とは、１回の膨張弁の開度調整で増減させる開度の調整量に対応する値である。そして、膨張弁の開度調整は、目標となる状態量と検出した状態量との差分に応じて行われる。例えば、状態量が上述した吐出温度の場合、検出した吐出温度が目標吐出温度より高いときは、正回転を示す極性を含むパルス信号を膨張弁に与え、検出した吐出温度が目標吐出温度より低いときは、逆回転を示す極性を含むパルス信号を膨張弁に与える。そして、膨張弁の開度の調整量の大きさに応じて、パルス信号のパルス数を変える、例えば、検出した吐出温度と目標吐出温度との温度差に応じて、膨張弁に与えるパルス信号のパルス数を変化させる。なお、以降の説明では、パルス信号に含まれるパルス数を増減する旨の説明を行う際に、単に「パルス数を増減」、「小さい／大きいパルス数」などと省略して記載する場合がある。 The opening degree of the expansion valve can be adjusted by giving a pulse signal including a polarity indicating the rotation direction of the pulse motor and a pulse number of pulses corresponding to the opening degree to be increased or decreased to the pulse motor provided in the expansion valve. When it is desired to increase the opening degree of the expansion valve, a pulse signal including a polarity indicating forward rotation (a polarity in which the pulse motor rotates in the direction of increasing the opening degree) and a predetermined number of pulses is given to open the expansion valve. When it is desired to reduce the degree, a pulse signal including a polarity indicating reverse rotation (a polarity in which the pulse motor rotates in a direction in which the opening degree decreases) and a pulse having a predetermined number of pulses is given. Here, the predetermined number of pulses is a value corresponding to the adjustment amount of the opening degree that is increased or decreased by adjusting the opening degree of the expansion valve once. Then, the opening degree adjustment of the expansion valve is performed according to the difference between the target state amount and the detected state amount. For example, when the state quantity is the above-mentioned discharge temperature, when the detected discharge temperature is higher than the target discharge temperature, a pulse signal including a polarity indicating forward rotation is given to the expansion valve, and the detected discharge temperature is lower than the target discharge temperature. When, a pulse signal including a polarity indicating reverse rotation is given to the expansion valve. Then, the number of pulses of the pulse signal is changed according to the magnitude of the adjustment amount of the opening degree of the expansion valve, for example, the pulse signal given to the expansion valve according to the temperature difference between the detected discharge temperature and the target discharge temperature. Change the number of pulses. In the following description, when explaining that the number of pulses included in the pulse signal is increased or decreased, it may be simply abbreviated as "increase or decrease the number of pulses", "small / large number of pulses", or the like. ..

特開平３−１７０７５３号公報Japanese Unexamined Patent Publication No. 3-170753

上述した、目標となる状態量と検出した状態量との差分に応じて膨張弁に与えられるパルス信号に含まれるパルス数は、凝縮器で凝縮して液状態となった冷媒が膨張弁を通過することを想定して決定されることが一般的である。従って、膨張弁を通過する冷媒が気液二相状態となった場合、つまり、膨張弁を通過する冷媒の密度が液状態である場合と比べて低くなった場合は、冷媒の密度が液状態である場合と同じパルス信号を膨張弁に与えることにより膨張弁開度を調整しても、冷媒回路の状態量を目標値とできない、もしくは、目標値とするのに時間がかかる恐れがあった。なお、空調運転時の外気温度が高いときや室内機が設置された部屋の断熱が悪いなどといった、空調負荷が高い状態であるときに、膨張弁を通過する冷媒が気液二相状態となりやすく、特に、省冷媒のために充填する冷媒量が従来の空気調和機より削減されている空気調和機で、膨張弁を通過する冷媒が気液二相状態となりやすい。 The number of pulses included in the pulse signal given to the expansion valve according to the difference between the target state amount and the detected state amount described above is such that the refrigerant condensed by the condenser and in a liquid state passes through the expansion valve. It is generally decided on the assumption that it will be done. Therefore, when the refrigerant passing through the expansion valve is in a gas-liquid two-phase state, that is, when the density of the refrigerant passing through the expansion valve is lower than that in the liquid state, the refrigerant density is in the liquid state. Even if the expansion valve opening is adjusted by giving the same pulse signal to the expansion valve as in the case of, the state amount of the refrigerant circuit may not be set to the target value, or it may take time to set the target value. .. When the air conditioning load is high, such as when the outside air temperature is high during air conditioning operation or the heat insulation of the room where the indoor unit is installed is poor, the refrigerant passing through the expansion valve tends to be in a gas-liquid two-phase state. In particular, in an air conditioner in which the amount of refrigerant to be filled for saving refrigerant is reduced as compared with the conventional air conditioner, the refrigerant passing through the expansion valve tends to be in a gas-liquid two-phase state.

本発明は以上述べた問題点を解決するものであって、空調運転時に膨張弁を通過する冷媒が気液二相状態となっても、好適に膨張弁の開度を調整できる空気調和機を提供することを目的とする。 The present invention solves the above-mentioned problems, and provides an air conditioner capable of suitably adjusting the opening degree of the expansion valve even when the refrigerant passing through the expansion valve is in a gas-liquid two-phase state during air conditioning operation. The purpose is to provide.

上記の課題を解決するために、本発明の空気調和機は、圧縮機と、凝縮器と、膨張弁と、蒸発器とが冷媒配管で接続されて形成される冷媒回路と、膨張弁を流れる冷媒が、気液二相状態、あるいは、液状態のいずれの状態であるかを検出する第１検出手段と、冷媒回路を循環する冷媒の温度あるいは圧力を含む状態量を検出する第２検出手段と、膨張弁の開度を調整する制御手段とを有する。そして、第１検出手段の検出結果と第２検出手段の検出結果とに基づいて、膨張弁の開度が調整される。 In order to solve the above problems, the air conditioner of the present invention flows through a refrigerant circuit formed by connecting a compressor, a condenser, an expansion valve, and an evaporator by a refrigerant pipe, and an expansion valve. A first detecting means for detecting whether the refrigerant is in a gas-liquid two-phase state or a liquid state, and a second detecting means for detecting a state amount including the temperature or pressure of the refrigerant circulating in the refrigerant circuit. And a control means for adjusting the opening degree of the expansion valve. Then, the opening degree of the expansion valve is adjusted based on the detection result of the first detection means and the detection result of the second detection means.

上記のように構成した本発明の空気調和機は、空調運転時に膨張弁を通過する冷媒の状態に応じて、好適に膨張弁の開度を調整できる。 The air conditioner of the present invention configured as described above can suitably adjust the opening degree of the expansion valve according to the state of the refrigerant passing through the expansion valve during the air conditioning operation.

本発明の実施形態における、空気調和機の説明図であり、（Ａ）は冷媒回路図、（Ｂ）は室内機制御手段のブロック図である。It is explanatory drawing of the air conditioner in embodiment of this invention, (A) is a refrigerant circuit diagram, (B) is a block diagram of an indoor unit control means. 本発明の実施形態における、膨張弁開度テーブルである。It is an expansion valve opening degree table in embodiment of this invention. 本発明の実施形態における、冷房運転時の膨張弁の開度調整を行う際の処理を示すフローチャートである。It is a flowchart which shows the process at the time of adjusting the opening degree of the expansion valve at the time of a cooling operation in embodiment of this invention.

以下、本発明の実施の形態を、添付図面に基づいて詳細に説明する。実施形態としては、室外機と室内機が冷媒配管で接続された空気調和装置を例に挙げて説明する。尚、本発明は以下の実施形態に限定されることはなく、本発明の主旨を逸脱しない範囲で種々変形することが可能である。 Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. As an embodiment, an air conditioner in which the outdoor unit and the indoor unit are connected by a refrigerant pipe will be described as an example. The present invention is not limited to the following embodiments, and various modifications can be made without departing from the gist of the present invention.

図１（Ａ）に示すように、本実施例における空気調和機１は、屋外に設置される室外機２と、室外機２に液管４およびガス管５で接続されて屋内に設置される室内機３を備えている。詳細には、室外機２の閉鎖弁２５と室内機３の液管接続部３３とが液管４で接続されている。また、室外機２の閉鎖弁２６と室内機３のガス管接続部３４とがガス管５で接続されている。このように、室外機２と室内機３とが液管４とガス管５で接続されることで、空気調和機１の冷媒回路１０が形成されている。 As shown in FIG. 1A, the air conditioner 1 in this embodiment is installed indoors by being connected to an outdoor unit 2 installed outdoors and an outdoor unit 2 by a liquid pipe 4 and a gas pipe 5. It is equipped with an indoor unit 3. Specifically, the closing valve 25 of the outdoor unit 2 and the liquid pipe connecting portion 33 of the indoor unit 3 are connected by a liquid pipe 4. Further, the closing valve 26 of the outdoor unit 2 and the gas pipe connecting portion 34 of the indoor unit 3 are connected by a gas pipe 5. In this way, the outdoor unit 2 and the indoor unit 3 are connected by the liquid pipe 4 and the gas pipe 5, so that the refrigerant circuit 10 of the air conditioner 1 is formed.

＜室外機の構成＞
まずは、室外機２について説明する。室外機２は、圧縮機２１と、四方弁２２と、室外熱交換器２３と、膨張弁２４と、液管４の一端が接続された閉鎖弁２５と、ガス管５の一端が接続された閉鎖弁２６と、アキュムレータ２７と、室外ファン２８と、室外機制御手段２００とを備えている。そして、室外ファン２８および室外機制御手段２００を除くこれら各々の装置が以下で詳述する各々の冷媒配管で相互に接続されて、冷媒回路１０の一部をなす室外機冷媒回路１０ａを形成している。 <Outdoor unit configuration>
First, the outdoor unit 2 will be described. In the outdoor unit 2, the compressor 21, the four-way valve 22, the outdoor heat exchanger 23, the expansion valve 24, the closing valve 25 to which one end of the liquid pipe 4 is connected, and one end of the gas pipe 5 are connected. It includes a closing valve 26, an accumulator 27, an outdoor fan 28, and an outdoor unit control means 200. Then, each of these devices except the outdoor fan 28 and the outdoor unit control means 200 are connected to each other by the respective refrigerant pipes described in detail below to form the outdoor unit refrigerant circuit 10a forming a part of the refrigerant circuit 10. ing.

圧縮機２１は、インバータにより回転数が制御される図示しないモータによって駆動されることで、運転容量を可変できる能力可変型圧縮機である。図１（Ａ）に示すように、圧縮機２１の冷媒吐出側は、後述する四方弁２２のポートａと吐出管６１で接続されている。また、圧縮機２１の冷媒吸入側は、アキュムレータ２７の冷媒流出側と吸入管６６で接続されている。 The compressor 21 is a variable capacity compressor whose operating capacity can be changed by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. As shown in FIG. 1A, the refrigerant discharge side of the compressor 21 is connected to the port a of the four-way valve 22 described later by a discharge pipe 61. Further, the refrigerant suction side of the compressor 21 is connected to the refrigerant outflow side of the accumulator 27 by a suction pipe 66.

四方弁２２は、冷媒の流れる方向を切り換えるための弁であり、ａ、ｂ、ｃ、ｄの４つのポートを備えている。ポートａは、上述したように圧縮機２１の冷媒吐出側と吐出管６１で接続されている。ポートｂは、室外熱交換器２３の一方の冷媒出入口と冷媒配管６２で接続されている。ポートｃは、アキュムレータ２７の冷媒流入側と冷媒配管６５で接続されている。そして、ポートｄは、閉鎖弁２６と室外機ガス管６４で接続されている。 The four-way valve 22 is a valve for switching the flow direction of the refrigerant, and has four ports a, b, c, and d. As described above, the port a is connected to the refrigerant discharge side of the compressor 21 by a discharge pipe 61. The port b is connected to one of the refrigerant inlets and outlets of the outdoor heat exchanger 23 by a refrigerant pipe 62. The port c is connected to the refrigerant inflow side of the accumulator 27 by a refrigerant pipe 65. The port d is connected to the closing valve 26 by an outdoor unit gas pipe 64.

室外熱交換器２３は、冷媒と、室外ファン２８の回転により熱交換器室２００ｂに取り込まれた外気を熱交換させるものである。室外熱交換器２３の一方の冷媒出入口は、上述したように四方弁２２のポートｂと冷媒配管６２で接続されている。室外熱交換器２３の他方の冷媒出入口は、閉鎖弁２５と室外機液管６３で接続されている。室外熱交換器２３は、空気調和機１が冷房運転を行う際は凝縮器として機能し、暖房運転を行う際は蒸発器として機能する。 The outdoor heat exchanger 23 exchanges heat between the refrigerant and the outside air taken into the heat exchanger room 200b by the rotation of the outdoor fan 28. One of the refrigerant inlets and outlets of the outdoor heat exchanger 23 is connected to the port b of the four-way valve 22 by the refrigerant pipe 62 as described above. The other refrigerant inlet / outlet of the outdoor heat exchanger 23 is connected to the closing valve 25 by an outdoor unit liquid pipe 63. The outdoor heat exchanger 23 functions as a condenser when the air conditioner 1 performs a cooling operation, and functions as an evaporator when the air conditioner 1 performs a heating operation.

膨張弁２４は、室外機液管６３に設けられている。膨張弁２４は、図示しないパルスモータにより駆動される電子膨張弁であり、パルスモータの回転方向を示す極性（例えば、正回転（プラス）：開度が大きくなる方向に回転、逆回転（マイナス）：開度が小さくなる方向に回転）と所定のパルス数のパルスとを含むパルス信号をパルスモータに与えることによって開度が調整される。ここで、所定のパルス数とは、１回の膨張弁２４の開度調整で増減させる開度の調整量に対応するパルスの数である。具体的には、膨張弁２４の開度を大きくする場合は、プラスの極性が付加された所定のパルス数のパルスを含むパルス信号を膨張弁２４に与え、膨張弁２４の開度を小さくする場合は、マイナスの極性が付加された所定のパルス数のパルスを含むパルス信号を膨張弁２４に与える。膨張弁２４は、室内機３で要求される冷房能力や暖房能力に応じてその開度が調整されることで、室外熱交換器２３に流れる冷媒量、および、室内機３（の室内熱交換器３１）に流れる冷媒量を調整する。 The expansion valve 24 is provided in the outdoor unit liquid pipe 63. The expansion valve 24 is an electronic expansion valve driven by a pulse motor (not shown), and has a polarity indicating the rotation direction of the pulse motor (for example, forward rotation (plus): rotation in a direction in which the opening degree increases, reverse rotation (minus)). : The opening degree is adjusted by giving a pulse signal including (rotating in a direction in which the opening degree becomes smaller) and a pulse having a predetermined number of pulses to the pulse motor. Here, the predetermined number of pulses is the number of pulses corresponding to the adjustment amount of the opening degree that is increased or decreased by adjusting the opening degree of the expansion valve 24 once. Specifically, when increasing the opening degree of the expansion valve 24, a pulse signal including a predetermined number of pulses to which a positive polarity is added is given to the expansion valve 24, and the opening degree of the expansion valve 24 is decreased. In this case, a pulse signal including a predetermined number of pulses to which a negative polarity is added is given to the expansion valve 24. The opening degree of the expansion valve 24 is adjusted according to the cooling capacity and the heating capacity required by the indoor unit 3, so that the amount of refrigerant flowing through the outdoor heat exchanger 23 and the indoor heat exchange of the indoor unit 3 (indoor heat exchange). The amount of refrigerant flowing in the vessel 31) is adjusted.

アキュムレータ２７は、前述したように、冷媒流入側と四方弁２２のポートｃが冷媒配管６５で接続され、冷媒流出側と圧縮機２１の冷媒吸入側が吸入管６６で接続されている。アキュムレータ２７は、冷媒配管６５からアキュムレータ２７の内部に流入した気液二相冷媒を液冷媒とガス冷媒とに分離し、分離したガス冷媒のみを吸入管６６を介して圧縮機２１に吸入させる。 In the accumulator 27, as described above, the refrigerant inflow side and the port c of the four-way valve 22 are connected by the refrigerant pipe 65, and the refrigerant outflow side and the refrigerant suction side of the compressor 21 are connected by the suction pipe 66. The accumulator 27 separates the gas-liquid two-phase refrigerant that has flowed into the accumulator 27 from the refrigerant pipe 65 into a liquid refrigerant and a gas refrigerant, and causes the compressor 21 to suck only the separated gas refrigerant through the suction pipe 66.

室外ファン２８は樹脂材で形成されたプロペラファンであり、室外機２の図示しない吹出口に臨むように配置されている。室外ファン２８は、図示しないファンモータの駆動によって回転することで、室外機２の図示しない吸込口から室外機２の内部に外気を取り込み、室外熱交換器２３において冷媒と熱交換した外気を図示しない吹出口から室外機２の外部へ放出する。 The outdoor fan 28 is a propeller fan made of a resin material, and is arranged so as to face an air outlet (not shown) of the outdoor unit 2. The outdoor fan 28 is rotated by driving a fan motor (not shown) to take in outside air from a suction port (not shown) of the outdoor unit 2 into the outdoor unit 2 and exchange heat with the refrigerant in the outdoor heat exchanger 23. Do not discharge from the air outlet to the outside of the outdoor unit 2.

以上説明した構成の他に、室外機２には各々の種のセンサが設けられている。図１（Ａ）に示すように、吐出管６１には、圧縮機２１から吐出される冷媒の圧力を検出する吐出圧力センサ７１と、圧縮機２１から吐出される冷媒の温度を検出する吐出温度センサ７３が設けられている。冷媒配管６５におけるアキュムレータ２７の冷媒流入側近傍には、圧縮機２１に吸入される冷媒の圧力を検出する吸入圧力センサ７２と、圧縮機２１に吸入される冷媒の温度を検出する吸入温度センサ７４とが設けられている。 In addition to the configuration described above, the outdoor unit 2 is provided with sensors of each type. As shown in FIG. 1A, the discharge pipe 61 has a discharge pressure sensor 71 that detects the pressure of the refrigerant discharged from the compressor 21, and a discharge temperature that detects the temperature of the refrigerant discharged from the compressor 21. A sensor 73 is provided. In the vicinity of the refrigerant inflow side of the accumulator 27 in the refrigerant pipe 65, a suction pressure sensor 72 that detects the pressure of the refrigerant sucked into the compressor 21 and a suction temperature sensor 74 that detects the temperature of the refrigerant sucked into the compressor 21 And are provided.

室外機液管６３における室外熱交換器２３と膨張弁２４との間には、室外熱交換器２３に出入りする冷媒の温度を検知するための冷媒温度センサ７５が設けられている。そして、室外機２の図示しない吸込口付近には、室外機２の内部に取り込まれた外気の温度、すなわち外気温度を検出する外気温度センサ７６が備えられている。 A refrigerant temperature sensor 75 for detecting the temperature of the refrigerant entering and exiting the outdoor heat exchanger 23 is provided between the outdoor heat exchanger 23 and the expansion valve 24 in the outdoor unit liquid pipe 63. An outside air temperature sensor 76 for detecting the temperature of the outside air taken into the inside of the outdoor unit 2, that is, the outside air temperature is provided in the vicinity of the suction port (not shown) of the outdoor unit 2.

また、室外機２には、本発明の制御手段である室外機制御手段２００が備えられている。室外機制御手段２００は、室外機２の図示しない電装品箱に格納された制御基板に搭載されており、図１（Ｂ）に示すように、ＣＰＵ２１０と、記憶部２２０と、通信部２３０と、センサ入力部２４０とを備えている。 Further, the outdoor unit 2 is provided with the outdoor unit control means 200, which is the control means of the present invention. The outdoor unit control means 200 is mounted on a control board housed in an electrical component box (not shown) of the outdoor unit 2, and as shown in FIG. 1B, the CPU 210, the storage unit 220, and the communication unit 230 , The sensor input unit 240 is provided.

記憶部２２０は、例えばフラッシュメモリであり、室外機２の制御プログラムや各種センサからの検出信号に対応した検出値、圧縮機２１や室外機ファン２８の駆動状態、膨張弁２４の開度、室内機３から送信される運転情報（運転／停止情報、冷房／暖房等の運転モード、室内機３の要求する冷房能力あるいは暖房能力などを含む）、後述する膨張弁開度テーブル３００などを記憶する。通信部２３０は、室内機３との通信を行うインターフェイスである。センサ入力部２４０は、室外機２の各種センサでの検出結果を取り込んでＣＰＵ２１０に出力する。 The storage unit 220 is, for example, a flash memory, and has a detection value corresponding to a control program of the outdoor unit 2 and detection signals from various sensors, a driving state of the compressor 21 and the outdoor unit fan 28, an opening degree of the expansion valve 24, and indoors. Stores operation information (including operation / stop information, operation modes such as cooling / heating, cooling capacity or heating capacity required by the indoor unit 3), expansion valve opening table 300, which will be described later, and the like, which are transmitted from the machine 3. .. The communication unit 230 is an interface for communicating with the indoor unit 3. The sensor input unit 240 captures the detection results of the various sensors of the outdoor unit 2 and outputs them to the CPU 210.

ＣＰＵ２１０は、センサ入力部２４０を介して各種センサでの検出値を定期的（例えば、３０秒毎）に取り込むとともに、室内機３から送信される運転情報を含む信号が通信部２３０を介して入力される。ＣＰＵ２１０は、これら入力された各種情報に基づいて、膨張弁２４の開度調整、圧縮機２１や室外機ファン２８の駆動制御などを行う。 The CPU 210 periodically (for example, every 30 seconds) captures the detected values of various sensors via the sensor input unit 240, and inputs a signal including operation information transmitted from the indoor unit 3 via the communication unit 230. Will be done. The CPU 210 adjusts the opening degree of the expansion valve 24, controls the drive of the compressor 21 and the outdoor unit fan 28, and the like based on the various input information.

＜室内機の構成＞
次に図１を用いて、室内機３について説明する。室内機３は、室内熱交換器３１と、液管４の他端が接続された液管接続部３３と、ガス管５の他端が接続されたガス管接続部３４と、室内ファン３２を備えている。そして、室内ファン３２を除くこれら各々の装置が以下で詳述する各々の冷媒配管で相互に接続されて、冷媒回路１０の一部をなす室内機冷媒回路１０ｂを形成している。 <Composition of indoor unit>
Next, the indoor unit 3 will be described with reference to FIG. The indoor unit 3 includes an indoor heat exchanger 31, a liquid pipe connecting portion 33 to which the other end of the liquid pipe 4 is connected, a gas pipe connecting portion 34 to which the other end of the gas pipe 5 is connected, and an indoor fan 32. I have. Then, each of these devices except the indoor fan 32 is connected to each other by the respective refrigerant pipes described in detail below to form the indoor unit refrigerant circuit 10b forming a part of the refrigerant circuit 10.

室内熱交換器３１は、冷媒と、室内ファン３２の回転により図示しない吸込口から室内機３の内部に取り込まれた室内空気を熱交換させるものである。室内熱交換器３１の一方の冷媒出入口が液管接続部３３と室内機液管６７で接続されている。室内熱交換器３１の他方の冷媒出入口がガス管接続部３４と室内機ガス管６８で接続されている。室内熱交換器３１は、室内機３が冷房運転を行う場合は蒸発器として機能し、室内機３が暖房運転を行う場合は凝縮器として機能する。尚、液管接続部３３やガス管接続部３４では、各々の冷媒配管が溶接やフレアナット等により接続されている。 The indoor heat exchanger 31 exchanges heat between the refrigerant and the indoor air taken into the interior of the indoor unit 3 from a suction port (not shown) by the rotation of the indoor fan 32. One refrigerant inlet / outlet of the indoor heat exchanger 31 is connected to the liquid pipe connecting portion 33 by the indoor unit liquid pipe 67. The other refrigerant inlet / outlet of the indoor heat exchanger 31 is connected to the gas pipe connecting portion 34 by the indoor unit gas pipe 68. The indoor heat exchanger 31 functions as an evaporator when the indoor unit 3 performs a cooling operation, and functions as a condenser when the indoor unit 3 performs a heating operation. In the liquid pipe connecting portion 33 and the gas pipe connecting portion 34, the respective refrigerant pipes are connected by welding, flare nuts, or the like.

室内ファン３２は樹脂材で形成されたクロスフローファンであり、室内熱交換器３１の近傍に配置されている。室内ファン３１は、図示しないファンモータによって回転することで、図示しない吸込口から室内機３の内部に室内空気を取り込み、室内熱交換器３１において冷媒と熱交換した室内空気を図示しない吹出口から室内へ吹き出す。 The indoor fan 32 is a cross-flow fan made of a resin material, and is arranged in the vicinity of the indoor heat exchanger 31. The indoor fan 31 is rotated by a fan motor (not shown) to take indoor air into the indoor unit 3 from a suction port (not shown) and exchange heat with the refrigerant in the indoor heat exchanger 31 from an outlet (not shown). Blow into the room.

以上説明した構成の他に、室内機３には各種のセンサが設けられている。室内機液管６７には、室内熱交換器３１に出入りする冷媒の温度を検出する液側温度センサ７７が設けられている。室内機ガス管６８には、室内熱交換器３１に出入りする冷媒の温度を検出するガス側温度センサ７８が設けられている。そして、室内機３の図示しない吸込口付近には、室内機３の内部に流入する室内空気の温度、すなわち室内温度を検出する室内温度センサ７９が備えられている。 In addition to the configuration described above, the indoor unit 3 is provided with various sensors. The indoor unit liquid pipe 67 is provided with a liquid side temperature sensor 77 that detects the temperature of the refrigerant entering and exiting the indoor heat exchanger 31. The indoor unit gas pipe 68 is provided with a gas side temperature sensor 78 that detects the temperature of the refrigerant entering and exiting the indoor heat exchanger 31. An indoor temperature sensor 79 that detects the temperature of the indoor air flowing into the indoor unit 3, that is, the indoor temperature is provided in the vicinity of the suction port (not shown) of the indoor unit 3.

＜空調運転時の動作＞
次に、本実施形態における空気調和機１の空調運転時の冷媒回路１０における冷媒の流れや各々の装置の動作について、図１（Ａ）を用いて説明する。以下の説明では、まず、空気調和機１が冷房運転を行う場合について説明し、次に、空気調和機１が暖房運転を行う場合について説明する。尚、図１における実線矢印は冷媒回路１０における冷房運転時の冷媒の流れを示し、破線矢印は冷媒回路１０における暖房運転時の冷媒の流れを示している。 <Operation during air conditioning operation>
Next, the flow of the refrigerant in the refrigerant circuit 10 during the air conditioning operation of the air conditioner 1 and the operation of each device in the present embodiment will be described with reference to FIG. 1 (A). In the following description, first, a case where the air conditioner 1 performs a cooling operation will be described, and then a case where the air conditioner 1 performs a heating operation will be described. The solid line arrow in FIG. 1 indicates the flow of the refrigerant during the cooling operation in the refrigerant circuit 10, and the broken line arrow indicates the flow of the refrigerant during the heating operation in the refrigerant circuit 10.

＜冷房運転＞
空気調和機１が冷房運転を行う場合、図１（Ａ）に示すように四方弁２２が実線で示す状態、すなわち、四方弁２２のポートａとポートｂとが連通するよう、また、ポートｃとポートｄとが連通するよう、切り替えられる。これにより、冷媒回路１０において実線矢印で示す方向に冷媒が循環し、室外熱交換器２３が凝縮器として機能するとともに室内熱交換器３１が蒸発器として機能する冷房サイクルとなる。 <Cooling operation>
When the air conditioner 1 performs the cooling operation, the four-way valve 22 is shown by a solid line as shown in FIG. 1 (A), that is, the port a and the port b of the four-way valve 22 communicate with each other and the port c. And port d are switched so as to communicate with each other. As a result, the refrigerant circulates in the direction indicated by the solid arrow in the refrigerant circuit 10, and the outdoor heat exchanger 23 functions as a condenser and the indoor heat exchanger 31 functions as an evaporator.

圧縮機２１から吐出された高圧の冷媒は、吐出管６１を流れて四方弁２２に流入し、四方弁２２から冷媒配管６２を流れて室外熱交換器２３に流入する。室外熱交換器２３に流入した冷媒は、室外ファン２８の回転により室外機２の内部に取り込まれた外気と熱交換を行って凝縮する。 The high-pressure refrigerant discharged from the compressor 21 flows through the discharge pipe 61 and flows into the four-way valve 22, and flows from the four-way valve 22 through the refrigerant pipe 62 and flows into the outdoor heat exchanger 23. The refrigerant flowing into the outdoor heat exchanger 23 exchanges heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 28 and condenses.

室外熱交換器２３から流出した冷媒は室外機液管６３を流れ、吐出温度が目標吐出温度となるように開度が調整された膨張弁２４および閉鎖弁２５を介して液管４に流出する。液管４を流れ、液管接続部３３を介して室内機３に流入した冷媒は、室内機液管６７を流れて室内熱交換器３１に流入する。 The refrigerant flowing out of the outdoor heat exchanger 23 flows through the outdoor unit liquid pipe 63, and flows out to the liquid pipe 4 via the expansion valve 24 and the closing valve 25 whose opening degree is adjusted so that the discharge temperature reaches the target discharge temperature. .. The refrigerant that has flowed through the liquid pipe 4 and has flowed into the indoor unit 3 through the liquid pipe connecting portion 33 flows through the indoor unit liquid pipe 67 and flows into the indoor heat exchanger 31.

室内熱交換器３１に流入した冷媒は、室内ファン３２の回転により室内機３の内部に取り込まれた室内空気と熱交換を行って蒸発する。このように、室内熱交換器３１が蒸発器として機能し、室内熱交換器３１で冷媒と熱交換を行った室内空気が図示しない吹出口から室内に吹き出されることによって、室内機３が設置された室内の冷房が行われる。 The refrigerant flowing into the indoor heat exchanger 31 evaporates by exchanging heat with the indoor air taken into the indoor unit 3 by the rotation of the indoor fan 32. In this way, the indoor heat exchanger 31 functions as an evaporator, and the indoor air that has exchanged heat with the refrigerant in the indoor heat exchanger 31 is blown into the room from an outlet (not shown), so that the indoor unit 3 is installed. The room is cooled.

室内熱交換器３１から流出した冷媒は、室内機ガス管６８を流れ、ガス管接続部３４を介してガス管５に流出する。ガス管５を流れる冷媒は、閉鎖弁２６を介して室外機２に流入し、室外機ガス管６４、四方弁２２、冷媒配管６５、アキュムレータ２７、吸入管６６の順に流れ、圧縮機２１に吸入されて再び圧縮される。 The refrigerant flowing out of the indoor heat exchanger 31 flows through the indoor unit gas pipe 68 and flows out to the gas pipe 5 via the gas pipe connecting portion 34. The refrigerant flowing through the gas pipe 5 flows into the outdoor unit 2 through the closing valve 26, flows in the order of the outdoor unit gas pipe 64, the four-way valve 22, the refrigerant pipe 65, the accumulator 27, and the suction pipe 66, and is sucked into the compressor 21. And then compressed again.

＜暖房運転＞
空気調和機１が暖房運転を行う場合は、図１（Ａ）に示すように四方弁２２が破線で示す状態、すなわち、四方弁２２のポートａとポートｄが連通するよう、また、ポートｂとポートｃが連通するよう、切り換えられる。これにより、冷媒回路１０において破線矢印で示す方向に冷媒が循環し、室外熱交換器２３が蒸発器として機能するとともに、室内熱交換器３１が凝縮器として機能する。 <Heating operation>
When the air conditioner 1 performs the heating operation, the four-way valve 22 is shown by a broken line as shown in FIG. 1 (A), that is, the port a and the port d of the four-way valve 22 communicate with each other, and the port b. And port c are switched so as to communicate with each other. As a result, the refrigerant circulates in the direction indicated by the broken line arrow in the refrigerant circuit 10, the outdoor heat exchanger 23 functions as an evaporator, and the indoor heat exchanger 31 functions as a condenser.

圧縮機２１から吐出された高圧の冷媒は、吐出管６１を流れて四方弁２２に流入し、四方弁２２から室外機ガス管６４、閉鎖弁２６、ガス管５、ガス管接続部３４の順に流れて室内機３に流入する。室内機３に流入した冷媒は、室内機ガス管６８を流れて室内熱交換器３１に流入し、室内ファン３２の回転により室内機３の内部に取り込まれた室内空気と熱交換を行って凝縮する。このように、室内熱交換器３１が凝縮器として機能し、室内熱交換器３１で冷媒と熱交換を行って加熱された室内空気が図示しない吹出口から室内に吹き出されることによって、室内機３が設置された室内の暖房が行われる。 The high-pressure refrigerant discharged from the compressor 21 flows through the discharge pipe 61 and flows into the four-way valve 22, and the outdoor unit gas pipe 64, the closing valve 26, the gas pipe 5, and the gas pipe connection portion 34 are in this order from the four-way valve 22. It flows and flows into the indoor unit 3. The refrigerant that has flowed into the indoor unit 3 flows through the indoor unit gas pipe 68 and flows into the indoor heat exchanger 31, and is condensed by exchanging heat with the indoor air taken into the indoor unit 3 by the rotation of the indoor fan 32. To do. In this way, the indoor heat exchanger 31 functions as a condenser, and the indoor heat exchanger 31 exchanges heat with the refrigerant to blow out the heated indoor air from an outlet (not shown) into the indoor unit. The room in which 3 is installed is heated.

室内熱交換器３１から流出した冷媒は室内機液管６７を流れ、液管接続部３３を介して液管４に流出する。液管４を流れる冷媒は、閉鎖弁２５を介して室外機２に流入する。室外機２に流入した冷媒は室外機液管６３を流れ、吐出温度が目標吐出温度となるように開度が調整された膨張弁２４を通過する際に減圧される。膨張弁２４で減圧された冷媒は室外熱交換器２３に流入し、室外ファン２８の回転によって室外機３の内部に取り込まれた外気と熱交換を行って蒸発する。 The refrigerant flowing out of the indoor heat exchanger 31 flows through the indoor unit liquid pipe 67 and flows out to the liquid pipe 4 via the liquid pipe connecting portion 33. The refrigerant flowing through the liquid pipe 4 flows into the outdoor unit 2 via the closing valve 25. The refrigerant flowing into the outdoor unit 2 flows through the outdoor unit liquid pipe 63, and is depressurized when passing through the expansion valve 24 whose opening degree is adjusted so that the discharge temperature reaches the target discharge temperature. The refrigerant decompressed by the expansion valve 24 flows into the outdoor heat exchanger 23, exchanges heat with the outside air taken into the outdoor unit 3 by the rotation of the outdoor fan 28, and evaporates.

室外熱交換器２３から冷媒配管６２に流出した冷媒は、四方弁２２、冷媒配管６５と流れてアキュムレータ２７に流入し、アキュムレータ２７で液冷媒とガス冷媒に分離される。そして、分離されたガス冷媒は、吸入管６６を介して圧縮機２１に吸入されて再び圧縮される。 The refrigerant flowing out from the outdoor heat exchanger 23 to the refrigerant pipe 62 flows through the four-way valve 22 and the refrigerant pipe 65, flows into the accumulator 27, and is separated into a liquid refrigerant and a gas refrigerant by the accumulator 27. Then, the separated gas refrigerant is sucked into the compressor 21 via the suction pipe 66 and compressed again.

＜膨張弁の開度調整について＞
次に、図１乃至図３を用いて、空気調和機１が冷房運転を行うときの膨張弁２４の開度調整について詳細に説明する。本実施形態の空気調和機１では、空調運転を行うときに、圧縮機２１から吐出される冷媒の温度である吐出温度が、予め定められた吐出温度の目標値である目標吐出温度（例えば、１００℃）となるように、膨張弁２４の開度が調整される。 <Adjustment of expansion valve opening>
Next, the opening degree adjustment of the expansion valve 24 when the air conditioner 1 performs the cooling operation will be described in detail with reference to FIGS. 1 to 3. In the air conditioner 1 of the present embodiment, when the air conditioning operation is performed, the discharge temperature, which is the temperature of the refrigerant discharged from the compressor 21, is the target discharge temperature (for example, the target discharge temperature, which is a predetermined discharge temperature target value). The opening degree of the expansion valve 24 is adjusted so as to be 100 ° C.).

なお、以下の説明では、吐出温度センサ７３で検出する吐出温度を実吐出温度Ｔｄｐ（単位：℃）、目標吐出温度をＴｄｔ（単位：℃）、目標吐出温度Ｔｄｔから実吐出温度Ｔｄｐを減じた吐出温度差をΔＴｄ（単位：℃）、膨張弁２４の図示しないパルスモータに与えられるパルス信号に含まれるパルスのパルス数である第１パルス数をＰ１（単位：ｐｌｓ）、同じくパルス信号に含まれるパルス数であり後述するように第１パルス数Ｐ１よりも所定値大きい値とされている第２パルス数をＰ２（単位：ｐｌｓ）とする。 In the following description, the discharge temperature detected by the discharge temperature sensor 73 is the actual discharge temperature Tdp (unit: ° C.), the target discharge temperature is Tdt (unit: ° C.), and the actual discharge temperature Tdt is subtracted from the target discharge temperature Tdt. The discharge temperature difference is ΔTd (unit: ° C.), and the first pulse number, which is the number of pulses included in the pulse signal given to the pulse motor (not shown) of the expansion valve 24, is included in P1 (unit: pls), which is also included in the pulse signal. The number of pulses to be generated, which is a predetermined value larger than the number of first pulses P1 as described later, is defined as P2 (unit: pls).

室外機制御手段２００の記憶部２２０には、図２に示す膨張弁開度テーブル３００が記憶されている。この膨張弁開度テーブル３００は、試験などを行って求められて予め記憶部２２０に記憶されているものであり、吐出温度差ΔＴｄに応じた第１パルス数Ｐ１と第２パルス数Ｐ２とが定められている。具体的には、吐出温度差ΔＴｄが小さいほど、つまり、実吐出温度Ｔｄｐが目標吐出温度Ｔｄｔより高い温度であるほど、第１パルス数Ｐ１と第２パルス数Ｐ２の値がそれぞれ大きな値とされている。また、吐出温度差ΔＴｄが大きいほど、つまり、実吐出温度Ｔｄｐが目標吐出温度Ｔｄｔより低い温度であるほど、第１パルス数Ｐ１と第２パルス数Ｐ２の値がそれぞれ小さな値とされている。これら第１パルス数Ｐ１および第２パルス数Ｐ２は、増減したい開度に対応した所定のパルス数である。 The expansion valve opening table 300 shown in FIG. 2 is stored in the storage unit 220 of the outdoor unit control means 200. The expansion valve opening table 300 is obtained by performing a test or the like and is stored in the storage unit 220 in advance, and the first pulse number P1 and the second pulse number P2 according to the discharge temperature difference ΔTd are It is set. Specifically, the smaller the discharge temperature difference ΔTd, that is, the higher the actual discharge temperature Tpd is higher than the target discharge temperature Tdt, the larger the values of the first pulse number P1 and the second pulse number P2 are set. ing. Further, the larger the discharge temperature difference ΔTd, that is, the lower the actual discharge temperature Tdt is than the target discharge temperature Tdt, the smaller the values of the first pulse number P1 and the second pulse number P2 are set. The first pulse number P1 and the second pulse number P2 are predetermined pulse numbers corresponding to the opening degree to be increased or decreased.

第１パルス数Ｐ１は空気調和機１を標準的な空調負荷となる条件（以降、標準負荷条件と記載する場合がある）下に置いて空調運転を行って求めた値である。空気調和機１が標準負荷条件下で運転しているときは、凝縮器として機能する熱交換器（冷房運転時は室外熱交換器２３、暖房運転時は室内熱交換器３１）から液管４に流出した冷媒が液状態となっていると考えられ、この液冷媒が膨張弁２４を通過するときに、吐出温度差ΔＴｄを小さくするために膨張弁２４の開度を大きくする、あるいは、開度を小さくするために必要なパルス数を第１パルス数Ｐ１としている。なお、標準負荷条件は、例えば冷房運転時の室内温度が２７℃／外気温度が１９℃、暖房運転時の室内温度が２０℃／外気温度が７℃である。 The first pulse number P1 is a value obtained by performing air conditioning operation by placing the air conditioner 1 under a condition that becomes a standard air conditioning load (hereinafter, may be referred to as a standard load condition). When the air conditioner 1 is operating under standard load conditions, the heat exchanger (outdoor heat exchanger 23 during cooling operation, indoor heat exchanger 31 during heating operation) to the liquid pipe 4 functions as a condenser. It is considered that the refrigerant flowing out to the air conditioner is in a liquid state, and when this liquid refrigerant passes through the expansion valve 24, the opening degree of the expansion valve 24 is increased or opened in order to reduce the discharge temperature difference ΔTd. The number of pulses required to reduce the degree is defined as the first pulse number P1. The standard load conditions are, for example, an indoor temperature of 27 ° C./outside air temperature of 19 ° C. during cooling operation, and an indoor temperature of 20 ° C./outside air temperature of 7 ° C. during heating operation.

しかし、空気調和機１が標準負荷条件より空調負荷が高い条件（以降、過負荷条件と記載する場合がある）に置かれて運転された場合は、凝縮器として機能する熱交換器から液管４に流出した冷媒が液状態とガス状態とが混ざった気液二相状態となっている可能性がある。このような条件下で、吐出温度差ΔＴｄを小さくするために第１パルス数Ｐ１を用いて開度を調整すると、実際に液管４を流れている冷媒の状態が第１パルス数Ｐ１を定めたときの前提条件である液冷媒の状態ではない（気液二相冷媒である）ことに起因して、第１パルス数Ｐ１を含むパルス信号を１回膨張弁２４に与えてその開度を調整した際に期待される、膨張弁２４を通過する冷媒量の変化量より少なくなる。この結果、実吐出温度Ｔｄｐが目標吐出温度Ｔｄｔとならない、もしくは、実吐出温度Ｔｄｐが目標吐出温度Ｔｄｔとなるのに時間がかかる恐れがある。なお、過負荷条件は、例えば冷房運転時の室内温度が３２℃／外気温度が４３℃、暖房運転時の室内温度が２７℃／外気温度が２４℃である、つまり、各温度が標準負荷条件時より高い温度である。 However, when the air conditioner 1 is operated under a condition where the air conditioning load is higher than the standard load condition (hereinafter, may be referred to as an overload condition), the heat exchanger that functions as a condenser is used as a liquid pipe. There is a possibility that the refrigerant flowing out to 4 is in a gas-liquid two-phase state in which a liquid state and a gas state are mixed. Under such conditions, when the opening degree is adjusted using the first pulse number P1 in order to reduce the discharge temperature difference ΔTd, the state of the refrigerant actually flowing through the liquid pipe 4 determines the first pulse number P1. Due to the fact that it is not in the state of the liquid refrigerant (which is a gas-liquid two-phase refrigerant), which is a precondition at the time, a pulse signal including the first pulse number P1 is once given to the expansion valve 24 to increase the opening degree. It is less than the amount of change in the amount of refrigerant passing through the expansion valve 24, which is expected when the adjustment is made. As a result, the actual discharge temperature Tdp may not reach the target discharge temperature Tdt, or it may take time for the actual discharge temperature Tdp to reach the target discharge temperature Tdt. The overload conditions are, for example, an indoor temperature of 32 ° C./outside air temperature of 43 ° C. during cooling operation and an indoor temperature of 27 ° C./outside air temperature of 24 ° C. during heating operation, that is, each temperature is a standard load condition. The temperature is higher than the hour.

そこで、本実施形態の空気調和機１では、凝縮器として機能する熱交換器から流出する冷媒の過冷却度（単位：ｄｅｇ。以降、実冷媒過冷却度ＳＣｐと記載する場合がある）を用いて、液管４を流れて膨張弁２４を通過する冷媒が液状態であるか気液二相状態であるかを推定し、膨張弁２４を通過する冷媒が液状態であると推定される場合は吐出温度差ΔＴｄに応じた第１パルス数Ｐ１を用いて、また、膨張弁２４を通過する冷媒が気液二相状態であると推定される場合は吐出温度差ΔＴｄに応じた第２パルス数Ｐ２を用いて膨張弁２４の開度を調整し、実吐出温度Ｔｄｐが目標吐出温度Ｔｄｔとなるようにする。
なお、本実施形態では、上述した膨張弁２４を通過する冷媒の密度の違いを考慮して、第２パルス数Ｐ２の値は、同じ吐出温度差ΔＴｄであるときの第１パルス数Ｐ１よりも大きい値、例えば、本実施形態では第１パルス数Ｐ１の４倍の値としているが、冷媒回路１０の規模（熱交換器の大きさや冷媒配管の長さなど）や冷媒回路１０に充填する冷媒の種類に応じて、第１パルス数Ｐ１の値と第２パルス数Ｐ２の値は適宜定めればよい。 Therefore, in the air conditioner 1 of the present embodiment, the supercooling degree of the refrigerant flowing out from the heat exchanger functioning as the condenser (unit: deg. Hereinafter, it may be referred to as the actual refrigerant supercooling degree SCp) is used. When it is estimated whether the refrigerant flowing through the liquid pipe 4 and passing through the expansion valve 24 is in a liquid state or a gas-liquid two-phase state, and the refrigerant passing through the expansion valve 24 is estimated to be in a liquid state. Uses the first pulse number P1 according to the discharge temperature difference ΔTd, and when it is estimated that the refrigerant passing through the expansion valve 24 is in a gas-liquid two-phase state, the second pulse corresponding to the discharge temperature difference ΔTd is used. The opening degree of the expansion valve 24 is adjusted by using the number P2 so that the actual discharge temperature Tdp becomes the target discharge temperature Tdt.
In the present embodiment, the value of the second pulse number P2 is larger than that of the first pulse number P1 when the same discharge temperature difference ΔTd is taken into consideration in consideration of the difference in the density of the refrigerant passing through the expansion valve 24 described above. A large value, for example, four times the value of the first pulse number P1 in the present embodiment, is set, but the scale of the refrigerant circuit 10 (size of heat exchanger, length of refrigerant pipe, etc.) and the refrigerant to be filled in the refrigerant circuit 10 The value of the first pulse number P1 and the value of the second pulse number P2 may be appropriately determined according to the type of.

膨張弁開度テーブル３００では、まず、吐出温度差ΔＴｄが−５℃以上５℃未満であるとき、つまり、実吐出温度Ｔｄｐが目標吐出温度Ｔｄｔに近い温度となっているときは、第１パルス数Ｐ１と第２パルス数Ｐ２はともに０ｐｌｓとされている、この場合、膨張弁２４の開度は変化しない。 In the expansion valve opening table 300, first, when the discharge temperature difference ΔTd is -5 ° C or more and less than 5 ° C, that is, when the actual discharge temperature Tdp is close to the target discharge temperature Tdt, the first pulse is generated. The number P1 and the number P2 of the second pulse are both set to 0 pls. In this case, the opening degree of the expansion valve 24 does not change.

次に、実吐出温度Ｔｄｐが目標吐出温度Ｔｄｔよりも低く吐出温度差ΔＴｄが５℃以上であるときは、吐出温度差ΔＴｄが大きくなるのにつれて、第１パルス数Ｐ１と第２パルス数Ｐ２はともに小さくなるように定められている。実吐出温度Ｔｄｐが目標吐出温度Ｔｄｔよりも低いときは、第１パルス数Ｐ１もしくは第２パルス数Ｐ２のパルスを含むパルス信号を膨張弁２４に与えることで、膨張弁２４の開度を小さくして圧縮機２１に戻る冷媒量を減少させる。これにより、圧縮機２１内部の温度が上昇し、実吐出温度Ｔｄｐが上昇する。 Next, when the actual discharge temperature Tdp is lower than the target discharge temperature Tdt and the discharge temperature difference ΔTd is 5 ° C. or higher, the first pulse number P1 and the second pulse number P2 become larger as the discharge temperature difference ΔTd increases. Both are set to be small. When the actual discharge temperature Tdp is lower than the target discharge temperature Tdt, the opening degree of the expansion valve 24 is reduced by giving a pulse signal including a pulse having the first pulse number P1 or the second pulse number P2 to the expansion valve 24. The amount of refrigerant returned to the compressor 21 is reduced. As a result, the temperature inside the compressor 21 rises, and the actual discharge temperature Tdp rises.

また、実吐出温度Ｔｄｐが目標吐出温度Ｔｄｔよりも高く吐出温度差ΔＴｄが−５℃未満であるときは、吐出温度差ΔＴｄが小さくなるのにつれて、第１パルス数Ｐ１と第２パルス数Ｐ２はともに大きくなるように定められている。実吐出温度Ｔｄｐが目標吐出温度Ｔｄｔよりも高いときは、第１パルス数Ｐ１もしくは第２パルス数Ｐ２のパルス数を含むパルス信号を膨張弁２４に与えることで、膨張弁２４の開度を大きくして圧縮機２１に戻る冷媒量を増加させる。これにより、圧縮機２１内部の温度が低下し、実吐出温度Ｔｄｐが低下する。
なお、実吐出温度Ｔｄｐが、本発明における冷媒回路１０を循環する冷媒の状態量であり、吐出温度センサ７３が本発明の第２検出手段である。 When the actual discharge temperature Tdp is higher than the target discharge temperature Tdt and the discharge temperature difference ΔTd is less than −5 ° C., the first pulse number P1 and the second pulse number P2 become smaller as the discharge temperature difference ΔTd becomes smaller. Both are set to be large. When the actual discharge temperature Tdp is higher than the target discharge temperature Tdt, the opening degree of the expansion valve 24 is increased by giving a pulse signal including the number of pulses of the first pulse number P1 or the second pulse number P2 to the expansion valve 24. The amount of refrigerant returned to the compressor 21 is increased. As a result, the temperature inside the compressor 21 is lowered, and the actual discharge temperature Tdp is lowered.
The actual discharge temperature Tdp is the state quantity of the refrigerant circulating in the refrigerant circuit 10 in the present invention, and the discharge temperature sensor 73 is the second detection means of the present invention.

また、液管４を流れる冷媒の状態を推定するために用いる実冷媒過冷却度ＳＣｐは、室外熱交換器２３が凝縮器として機能する冷房運転時は、吐出圧力センサ７１で検出した吐出圧力を用いて求めた室外熱交換器２３における凝縮温度から、冷媒温度センサ７５で検出した室外熱交換器２３から流出した冷媒の温度を減じて求めることができる。また、冷媒過冷却度ＳＣｐは、室内熱交換器３１が凝縮器として機能する暖房運転時は、吐出圧力センサ７１で検出した吐出圧力を用いて求めた室内熱交換器３１における凝縮温度から、液側温度センサ７７で検出した室内熱交換器３１から流出した冷媒の温度を減じて求めることができる。なお、上述した吐出圧力センサ７１と、冷媒温度センサ７５と、液側温度センサ７７と、これら各センサでの検出値を用いて実冷媒過冷却度ＳＣｐを算出する室外機制御手段２００が、本発明の第１検出手段である。 Further, the actual refrigerant supercooling degree SCp used for estimating the state of the refrigerant flowing through the liquid pipe 4 is the discharge pressure detected by the discharge pressure sensor 71 during the cooling operation in which the outdoor heat exchanger 23 functions as a condenser. It can be obtained by subtracting the temperature of the refrigerant flowing out from the outdoor heat exchanger 23 detected by the refrigerant temperature sensor 75 from the condensation temperature in the outdoor heat exchanger 23 obtained in use. Further, the refrigerant supercooling degree SCp is determined from the condensation temperature in the indoor heat exchanger 31 obtained by using the discharge pressure detected by the discharge pressure sensor 71 during the heating operation in which the indoor heat exchanger 31 functions as a condenser. It can be obtained by subtracting the temperature of the refrigerant flowing out from the indoor heat exchanger 31 detected by the side temperature sensor 77. The discharge pressure sensor 71, the refrigerant temperature sensor 75, the liquid side temperature sensor 77, and the outdoor unit control means 200 for calculating the actual refrigerant supercooling degree SCp using the values detected by each of these sensors are described in this article. This is the first detection means of the present invention.

実冷媒過冷却度ＳＣｐの検出は、吐出温度センサ７３で検出した実吐出温度Ｔｄｐを目標吐出温度Ｔｄｔに近づけるように膨張弁２４の開度を調整することと並行して、定期的（例えば、３分毎）に行われる。そして、検出した実冷媒過冷却度ＳＣｐが、予め定められた所定値（例えば、１ｄｅｇ。以降、所定冷媒過冷却度ＳＣｄと記載する場合がある）以下となり、かつ、実冷媒過冷却度ＳＣｐが所定冷媒過冷却度ＳＣｄ以下となる回数（以降、低ＳＣ回数ｋと記載する場合がある）が所定回数（例えば、３回。以降、所定回数ｋｄと記載する場合がある）以上連続した場合は、膨張弁２４を通過する冷媒が気液二相状態であると推定し、現在の膨張弁２４の開度に対応したパルス数に、吐出温度差ΔＴｄに応じた第２パルス数Ｐ２を増減した新たなパルス信号を膨張弁２４に与えることで、膨張弁２４の開度を調整する。一方、検出した実冷媒過冷却度ＳＣｐが所定冷媒過冷却度ＳＣｄより大きい、あるいは、検出した実冷媒過冷却度ＳＣｐが所定冷媒過冷却度ＳＣｄ以下である状態が低ＳＣ回数ｋ以上連続しない場合は、膨張弁２４を通過する冷媒が液状態であると推定し、吐出温度差ΔＴｄに応じた第１パルス数Ｐ１のパルスを含むパルス信号を膨張弁２４に与えることで、膨張弁２４の開度を調整する。 The detection of the actual refrigerant supercooling degree SCp is performed periodically (for example, in parallel with adjusting the opening degree of the expansion valve 24 so that the actual discharge temperature Tdp detected by the discharge temperature sensor 73 approaches the target discharge temperature Tdt. It is done every 3 minutes). Then, the detected actual refrigerant supercooling degree SCp is equal to or less than a predetermined predetermined value (for example, 1 deg. Hereinafter, it may be referred to as a predetermined refrigerant supercooling degree SCd), and the actual refrigerant supercooling degree SCp is When the number of times that the predetermined refrigerant supercooling degree SCd or less (hereinafter, may be described as low SC number k) is continuous for a predetermined number of times (for example, 3 times, hereinafter may be described as a predetermined number of times kd). , It is estimated that the refrigerant passing through the expansion valve 24 is in a gas-liquid two-phase state, and the number of second pulses P2 according to the discharge temperature difference ΔTd is increased or decreased to the number of pulses corresponding to the current opening degree of the expansion valve 24. By giving a new pulse signal to the expansion valve 24, the opening degree of the expansion valve 24 is adjusted. On the other hand, when the detected actual refrigerant supercooling degree SCp is larger than the predetermined refrigerant supercooling degree SCd, or the detected actual refrigerant supercooling degree SCp is equal to or less than the predetermined refrigerant supercooling degree SCd, the state is not continuous for a low SC number of times k or more. Presumes that the refrigerant passing through the expansion valve 24 is in a liquid state, and gives the expansion valve 24 a pulse signal including a pulse having a first pulse number P1 corresponding to the discharge temperature difference ΔTd to open the expansion valve 24. Adjust the degree.

＜膨張弁の開度調整を行う場合の処理の流れ＞
次に、図３を用いて、空気調和機１の空調運転時の膨張弁２４の開度調整に関わる処理について説明する。図３に示すのは、空調運転時に室外機制御手段２００のＣＰＵ２１０が行う膨張弁２４の開度調整に関わる処理の流れを示すフローチャートである。図３のフローチャートにおいて、ＳＴは処理のステップを表し、これに続く数字はステップの番号を表している。なお、図３では、膨張弁２４の開度調整以外の制御、例えば、室内機３から要求される空調能力に応じた圧縮機２１の駆動制御などについては、その説明を省略している。 <Process flow when adjusting the opening of the expansion valve>
Next, with reference to FIG. 3, a process related to adjusting the opening degree of the expansion valve 24 during the air conditioning operation of the air conditioner 1 will be described. FIG. 3 is a flowchart showing a flow of processing related to adjusting the opening degree of the expansion valve 24 performed by the CPU 210 of the outdoor unit control means 200 during the air conditioning operation. In the flowchart of FIG. 3, ST represents a processing step, and the number following it represents a step number. Note that, in FIG. 3, the description of the control other than the adjustment of the opening degree of the expansion valve 24, for example, the drive control of the compressor 21 according to the air conditioning capacity required from the indoor unit 3 is omitted.

空気調和機１が運転を開始するとき、ＣＰＵ２１０は、膨張弁２４の開度を初期開度とするとともに、低ＳＣ回数ｋを０とする（ＳＴ１）、ここで、膨張弁２４の初期開度とは、空気調和機１が運転を開始して圧縮機２１が起動してから、冷媒回路１０に冷媒が循環して冷媒回路１０が安定するまで、つまり、吐出温度センサ７３で検出する実吐出温度Ｔｄｐの値が安定するまでの膨張弁２４の開度であり、圧縮機２１の能力によって決められるものである。一例として初期開度は、膨張弁２４のパルスモータに与えるパルス信号に含まれるパルスのパルス数が１００ｐｌｓに相当する開度である。 When the air conditioner 1 starts operation, the CPU 210 sets the opening degree of the expansion valve 24 as the initial opening degree and sets the low SC number k to 0 (ST1), where the initial opening degree of the expansion valve 24 is set to 0. This means that after the air conditioner 1 starts operation and the compressor 21 starts, until the refrigerant circulates in the refrigerant circuit 10 and the refrigerant circuit 10 stabilizes, that is, the actual discharge detected by the discharge temperature sensor 73. It is the opening degree of the expansion valve 24 until the value of the temperature Tdp stabilizes, and is determined by the capacity of the compressor 21. As an example, the initial opening degree is an opening degree in which the number of pulses included in the pulse signal given to the pulse motor of the expansion valve 24 corresponds to 100 pls.

次に、ＣＰＵ２１０は、実冷媒過冷却度ＳＣｐを算出するとともに、実吐出温度Ｔｄｐを検出して吐出温度差ΔＴｄを算出する（ＳＴ２）。具体的には、ＣＰＵ２１０は、室外熱交換器２３が凝縮器として機能する冷房運転時は、吐出圧力センサ７１で検出した吐出圧力をセンサ入力部２４０を介して取り込み、取り込んだ吐出圧力を用いて室外熱交換器２３における凝縮温度を求める。また、ＣＰＵ２１０は、冷媒温度センサ７５で検出した冷媒の温度をセンサ入力部２４０を介して取り込む。そして、ＣＰＵ２１０は、求めた凝縮温度から取り込んだ冷媒の温度を減じて実冷媒過冷却度ＳＣｐを算出する。また、ＣＰＵ２１０は、室内熱交換器３１が凝縮器として機能する暖房運転時は、室内機３の液側温度センサ７７で検出した冷媒の温度を通信部２３０を介して取り込み、取り込んだ吐出圧力を用いて求めた室内熱交換器３１における凝縮温度から取り込んだ冷媒の温度を減じて実冷媒過冷却度ＳＣｐを算出する。また、ＣＰＵ２１０は、吐出温度センサ７３で検出した実吐出温度Ｔｄｐをセンサ入力部２４０を介して取り込み、記憶部２２０に記憶している目標吐出温度Ｔｄｔから取り込んだ実吐出温度Ｔｄｐを減じて吐出温度差ΔＴｄを算出する。 Next, the CPU 210 calculates the actual refrigerant supercooling degree SCp, detects the actual discharge temperature Tdp, and calculates the discharge temperature difference ΔTd (ST2). Specifically, the CPU 210 takes in the discharge pressure detected by the discharge pressure sensor 71 via the sensor input unit 240 during the cooling operation in which the outdoor heat exchanger 23 functions as a condenser, and uses the taken-in discharge pressure. The condensation temperature in the outdoor heat exchanger 23 is obtained. Further, the CPU 210 captures the temperature of the refrigerant detected by the refrigerant temperature sensor 75 via the sensor input unit 240. Then, the CPU 210 calculates the actual refrigerant supercooling degree SCp by subtracting the temperature of the taken-in refrigerant from the obtained condensation temperature. Further, the CPU 210 takes in the temperature of the refrigerant detected by the liquid side temperature sensor 77 of the indoor unit 3 via the communication unit 230 during the heating operation in which the indoor heat exchanger 31 functions as a condenser, and takes in the taken-out discharge pressure. The actual refrigerant supercooling degree SCp is calculated by subtracting the temperature of the taken-in refrigerant from the condensation temperature in the indoor heat exchanger 31 obtained in use. Further, the CPU 210 takes in the actual discharge temperature Tdp detected by the discharge temperature sensor 73 via the sensor input unit 240, and subtracts the actual discharge temperature Tdp taken in from the target discharge temperature Tdt stored in the storage unit 220 to discharge the discharge temperature. Calculate the difference ΔTd.

次に、ＣＰＵ２１０は、ＳＴ３で検出した実冷媒過冷却度ＳＣｐが、記憶部２２０に記憶している所定冷媒過冷却度ＳＣｄ以下であるか否かを判断する（ＳＴ３）。実冷媒過冷却度ＳＣｐが所定冷媒過冷却度ＳＣｄ以下であれば（ＳＴ３−Ｙｅｓ）、ＣＰＵ２１０は、現在の低ＳＣ回数ｋに１をプラスし（ＳＴ４）、低ＳＣ回数ｋが所定回数Ｋｄ以上であるか否かを判断する（ＳＴ５）。 Next, the CPU 210 determines whether or not the actual refrigerant supercooling degree SCp detected in ST3 is equal to or less than the predetermined refrigerant supercooling degree SCd stored in the storage unit 220 (ST3). If the actual refrigerant supercooling degree SCp is equal to or less than the predetermined refrigerant supercooling degree SCd (ST3-Yes), the CPU 210 adds 1 to the current low SC number k (ST4), and the low SC number k is the predetermined number Kd or more. It is determined whether or not it is (ST5).

低ＳＣ回数ｋが所定回数Ｋｄ以上でなければ（ＳＴ５−Ｎｏ）、ＣＰＵ２１０は、ＳＴ２に処理を戻す。低ＳＣ回数ｋが所定回数Ｋｄ以上であれば（ＳＴ５−Ｙｅｓ）、ＣＰＵ２１０は、記憶部２２０に記憶している膨張弁開度テーブル３００を参照し、ＳＴ２で算出した吐出温度差ΔＴｄに応じた第２パルス数Ｐ２を抽出し（ＳＴ６）、抽出した第２パルス数Ｐ２のパルスを含むパルス信号を膨張弁２４に与えて（ＳＴ７）、ＳＴ２に処理を戻す。 If the low SC number k is not equal to or greater than the predetermined number Kd (ST5-No), the CPU 210 returns the process to ST2. If the low SC number k is equal to or greater than the predetermined number Kd (ST5-Yes), the CPU 210 refers to the expansion valve opening table 300 stored in the storage unit 220 and corresponds to the discharge temperature difference ΔTd calculated in ST2. The second pulse number P2 is extracted (ST6), a pulse signal including the extracted pulse of the second pulse number P2 is given to the expansion valve 24 (ST7), and the process is returned to ST2.

一方、ＳＴ３において、実冷媒過冷却度ＳＣｐが所定冷媒過冷却度ＳＣｄ以下でなければ（ＳＴ３−Ｎｏ）、ＣＰＵ２１０は、記憶部２２０に記憶している膨張弁開度テーブル３００を参照し、ＳＴ２で算出した吐出温度差ΔＴｄに応じた第１パルス数Ｐ１を抽出し（ＳＴ８）、抽出した第１パルス数Ｐ１のパルスを含むパルス信号を膨張弁２４に与える（ＳＴ９）。そして、ＣＰＵ２１０は、低ＳＣ回数ｋを０として（ＳＴ１０）、ＳＴ２に処理を戻す。 On the other hand, in ST3, if the actual refrigerant supercooling degree SCp is not equal to or less than the predetermined refrigerant supercooling degree SCd (ST3-No), the CPU 210 refers to the expansion valve opening table 300 stored in the storage unit 220 and ST2. The first pulse number P1 corresponding to the discharge temperature difference ΔTd calculated in (ST8) is extracted (ST8), and a pulse signal including the extracted pulse of the first pulse number P1 is given to the expansion valve 24 (ST9). Then, the CPU 210 sets the low SC number k to 0 (ST10) and returns the process to ST2.

以上説明したように、本実施形態の空気調和機１では、実冷媒過冷却度ＳＣｐを用いて膨張弁２４を通過する冷媒の状態を推定し、推定した結果に応じて第１パルス数Ｐ１と第２パルス数Ｐ２とを使い分ける。膨張弁２４を通過する冷媒が気液二相状態である場合に膨張弁２４の開度を調整する際に、液状態の冷媒が膨張弁２４を通過する場合に使用する第１パルス数Ｐ１より大きい第２パルス数Ｐ２を用いる。これにより、膨張弁２４を通過する冷媒が液状態である場合より冷媒の密度が小さい気液二相状態であっても、膨張弁２４を通過する冷媒が液状態である場合と同様に好適に膨張弁２４の開度を調整することができ、実吐出温度Ｔｄｐを目標吐出温度Ｔｄｔに速やかに近づけられる。 As described above, in the air conditioner 1 of the present embodiment, the state of the refrigerant passing through the expansion valve 24 is estimated using the actual refrigerant supercooling degree SCp, and the first pulse number P1 is set according to the estimated result. The second pulse number P2 is used properly. From the first pulse number P1 used when the liquid-state refrigerant passes through the expansion valve 24 when adjusting the opening degree of the expansion valve 24 when the refrigerant passing through the expansion valve 24 is in a gas-liquid two-phase state. A large second pulse number P2 is used. As a result, even in a gas-liquid two-phase state in which the density of the refrigerant is lower than in the case where the refrigerant passing through the expansion valve 24 is in the liquid state, it is preferable as in the case where the refrigerant passing through the expansion valve 24 is in the liquid state. The opening degree of the expansion valve 24 can be adjusted, and the actual discharge temperature Tdp can be quickly brought close to the target discharge temperature Tdt.

なお、以上説明した本発明の実施形態では、冷媒回路１０を循環する冷媒の温度あるいは圧力を含む状態量として実吐出温度Ｔｄｐを採用し、この実吐出温度Ｔｄｐを検出する吐出温度センサ７３を第２検出手段として説明した。しかし、本発明はこれに限られるものではなく、本実施形態における第１検出手段、つまり、吐出圧力センサ７１と、冷媒温度センサ７５と、液側温度センサ７７と、室外機制御手段２００とで求める実冷媒過冷却度ＳＣｐを状態量として採用し、実冷媒過冷却度ＳＣｐが予め定められる目標冷媒過冷却度となるように、膨張弁２４の開度を調整してもよい。この場合は、第１検出手段が第２検出手段を兼ねることになる。 In the embodiment of the present invention described above, the actual discharge temperature Tdp is adopted as the state quantity including the temperature or pressure of the refrigerant circulating in the refrigerant circuit 10, and the discharge temperature sensor 73 for detecting the actual discharge temperature Tdp is used. 2 Described as the detection means. However, the present invention is not limited to this, and the first detection means in the present embodiment, that is, the discharge pressure sensor 71, the refrigerant temperature sensor 75, the liquid side temperature sensor 77, and the outdoor unit control means 200. The desired actual refrigerant supercooling degree SCp may be adopted as the state quantity, and the opening degree of the expansion valve 24 may be adjusted so that the actual refrigerant supercooling degree SCp becomes a predetermined target refrigerant supercooling degree. In this case, the first detection means also serves as the second detection means.

また、上記状態量は、実吐出温度Ｔｄｐや実冷媒過冷却度ＳＣｐに限られるものではなく、例えば、蒸発器として機能する熱交換器から流出した冷媒の過熱度や、圧縮機２１に吸入される冷媒の過熱度など、冷媒回路１０を循環する冷媒の温度あるいは圧力を含み、これら各状態量を膨張弁２４の開度調整により変化させることで、冷媒回路１０動作を適切に制御できるものであればよい。 Further, the above-mentioned state amount is not limited to the actual discharge temperature Tdp and the actual refrigerant supercooling degree SCp, and is, for example, the degree of superheating of the refrigerant flowing out from the heat exchanger functioning as an evaporator or being sucked into the compressor 21. The operation of the refrigerant circuit 10 can be appropriately controlled by including the temperature or pressure of the refrigerant circulating in the refrigerant circuit 10, such as the degree of overheating of the refrigerant, and changing each of these states by adjusting the opening degree of the expansion valve 24. All you need is.

１空気調和装置
２室外機
３室内機
１０冷媒回路
２１圧縮機
２４膨張弁
７１吐出圧力センサ
７５冷媒温度センサ
７７液側温度センサ
２００室外機制御部
２１０ＣＰＵ
３００膨張弁開度テーブル
ｋ低ＳＣ回数
ｋｄ所定回数
Ｐ１第１パルス数
Ｐ２第２パルス数
ＳＣｐ実冷媒過冷却度
ＳＣｄ所定逓倍過冷却度
Ｔｄｐ実吐出温度
Ｔｄｔ目標吐出温度
ΔＴｄ吐出温度差 1 Air conditioner 2 Outdoor unit 3 Indoor unit 10 Refrigerant circuit 21 Compressor 24 Expansion valve 71 Discharge pressure sensor 75 Refrigerant temperature sensor 77 Liquid side temperature sensor 200 Outdoor unit control unit 210 CPU
300 Expansion valve opening table k Low SC number kd Predetermined number P1 1st pulse number P2 2nd pulse number SCp Actual refrigerant supercooling degree SCd Predetermined multiplication overcooling degree Tdp Actual discharge temperature Tdt Target discharge temperature ΔTd

Claims

A refrigerant circuit formed by connecting a compressor, a condenser, an expansion valve, and an evaporator with a refrigerant pipe,
A first detecting means for detecting whether the refrigerant flowing through the expansion valve is in a gas-liquid two-phase state or a liquid state.
A second detecting means for detecting a state quantity including the temperature or pressure of the refrigerant circulating in the refrigerant circuit, and
A control means for adjusting the opening degree of the expansion valve and
Have,
The opening degree of the expansion valve is adjusted based on the detection result of the first detection means and the detection result of the second detection means.
An air conditioner that features that.

When the refrigerant flowing through the expansion valve is detected by the first detecting means as a gas-liquid two-phase state, the number of pulses based on the state amount detected by the second detecting means is determined by the first detecting means. It is a value larger than the number of pulses based on the same amount of state when the refrigerant flowing through is detected as a liquid state.
The air conditioner according to claim 1, wherein the air conditioner is characterized by the above.

The first detection means detects the degree of supercooling of the actual refrigerant, which is the degree of supercooling of the refrigerant flowing out of the condenser.
The control means estimates whether the refrigerant flowing through the expansion valve is in a gas-liquid two-phase state or a liquid state by using the actual refrigerant supercooling degree detected by the first detection means. To do,
The air conditioner according to claim 1 or 2, wherein the air conditioner is characterized by the above.

The state quantity is the actual discharge temperature, which is the temperature of the refrigerant discharged from the compressor.
The second detecting means detects the actual discharge temperature and
The control means adds the number of pulses based on the actual discharge temperature detected by the second detection means to the expansion valve.
The air conditioner according to claim 1 to 3, wherein the air conditioner is characterized by the above.