JP7067319B2

JP7067319B2 - Air conditioner

Info

Publication number: JP7067319B2
Application number: JP2018123931A
Authority: JP
Inventors: 慎太郎真田; 佑廣崎; 亮 ▲高▼岡; 光哉青木; 達朗山▲崎▼
Original assignee: Fujitsu General Ltd
Current assignee: Fujitsu General Ltd
Priority date: 2018-06-29
Filing date: 2018-06-29
Publication date: 2022-05-16
Anticipated expiration: 2038-06-29
Also published as: JP2020003155A

Description

本発明は空気調和機に関わり、より詳細には、高圧側に気液分離器を備える空気調和機に関する。 The present invention relates to an air conditioner, and more particularly to an air conditioner provided with a gas-liquid separator on the high pressure side.

近年、地球温暖化防止の観点から、冷媒回路に地球温暖化係数の小さい冷媒、例えば、プロパンやイソブタンなどの炭化水素冷媒やＲ３２冷媒を充填する空気調和機が提案されている。しかし、これらの冷媒は可燃性冷媒であるので、冷媒回路から冷媒が漏洩した際に漏洩量を減らすために、冷媒回路に充填する冷媒量が削減される。冷媒の充填量を削減する方法として、室外機と室内機とを接続する液管を細くする方法がある。液管を細くすれば、液管が太い場合と比べて冷房運転時に液管を流れる冷媒量が少なくなるので、冷媒回路に充填する冷媒量を削減することができる。 In recent years, from the viewpoint of preventing global warming, an air conditioner has been proposed in which a refrigerant circuit is filled with a refrigerant having a small global warming potential, for example, a hydrocarbon refrigerant such as propane or isobutane or an R32 refrigerant. However, since these refrigerants are flammable refrigerants, the amount of refrigerant charged in the refrigerant circuit is reduced in order to reduce the amount of leakage when the refrigerant leaks from the refrigerant circuit. As a method of reducing the filling amount of the refrigerant, there is a method of thinning the liquid pipe connecting the outdoor unit and the indoor unit. If the liquid pipe is made thin, the amount of the refrigerant flowing through the liquid pipe during the cooling operation is smaller than that in the case where the liquid pipe is thick, so that the amount of the refrigerant charged in the refrigerant circuit can be reduced.

しかし、冷房運転時に、液冷媒とガス冷媒とが混ざった気液二相冷媒、つまり、密度の低い冷媒が液管を流れる際に、液管を流れる冷媒の速度が速くなって圧力損失が大きくなる。また、液管が細くなるほど冷媒が液管を流れる際の圧力損失が大きくなる。従って、液管を細くした空気調和機で冷房運転を行ったときに、液管を冷媒が流れる際の圧力損失が大きくなることに起因して、膨張弁の開度を全開としても室内機の室内熱交換器における蒸発能力が低下して室内機で要求される冷房能力を発揮できない恐れがある。 However, during cooling operation, when a gas-liquid two-phase refrigerant in which a liquid refrigerant and a gas refrigerant are mixed, that is, a low-density refrigerant flows through the liquid pipe, the speed of the refrigerant flowing through the liquid pipe becomes high and the pressure loss becomes large. Become. Further, the thinner the liquid pipe, the larger the pressure loss when the refrigerant flows through the liquid pipe. Therefore, when the cooling operation is performed by an air conditioner with a thin liquid pipe, the pressure loss when the refrigerant flows through the liquid pipe becomes large, so even if the opening of the expansion valve is fully opened, the indoor unit There is a risk that the evaporation capacity of the indoor heat exchanger will decrease and the cooling capacity required by the indoor unit will not be exhibited.

上記の問題を解決する方法として、室外機の室外熱交換器と室内機の室内熱交換器とを接続する液管に気液分離器を備え、冷房運転時に凝縮器として機能する室外熱交換器から流出して気液分離器に流入した冷媒を液冷媒とガス冷媒とに分離し、液冷媒のみを気液分離器から液管に流出させることが考えられる（例えば、特許文献１）。このように、気液分離器を用いて液管に液冷媒、つまり、密度の高い冷媒を流すことで、液管を冷媒が流れる際の圧力損失を低減できる。これにより、冷媒充填量の削減のために液管を細くしても、この液管の細さに起因する圧力損失の影響を低減でき、室内機で要求される冷房能力を発揮するのに必要な量の冷媒を室内機に流すことができる。 As a method of solving the above problem, an outdoor heat exchanger that is equipped with a gas-liquid separator in the liquid pipe connecting the outdoor heat exchanger of the outdoor unit and the indoor heat exchanger of the indoor unit and functions as a condenser during cooling operation. It is conceivable that the refrigerant flowing out of the gas-liquid separator and flowing into the gas-liquid separator is separated into a liquid refrigerant and a gas refrigerant, and only the liquid refrigerant flows out from the gas-liquid separator to the liquid pipe (for example, Patent Document 1). In this way, by flowing the liquid refrigerant, that is, the high-density refrigerant through the liquid pipe using the gas-liquid separator, the pressure loss when the refrigerant flows through the liquid pipe can be reduced. As a result, even if the liquid pipe is made thinner to reduce the amount of refrigerant charged, the effect of pressure loss due to the thinness of the liquid pipe can be reduced, and it is necessary to exert the cooling capacity required for the indoor unit. A large amount of refrigerant can be flowed to the indoor unit.

特開２００４－２７８８２５号公報Japanese Unexamined Patent Publication No. 2004-278825

しかし、気液分離器を用いて液管を流れる冷媒の密度を高くすれば、冷房運転時に冷媒回路を循環する冷媒のうちの多くが液管に存在することとなる。この場合、冷媒回路には、冷房運転時に液管に存在する冷媒量を考慮して、室内機で要求される冷房能力を発揮するのに必要な量の冷媒を充填しなければならない。従って、液管を細くしたにもかかわらず冷媒回路に充填する冷媒量の削減効果が小さくなるという問題があった。 However, if the density of the refrigerant flowing through the liquid pipe is increased by using the gas-liquid separator, most of the refrigerant circulating in the refrigerant circuit during the cooling operation will be present in the liquid pipe. In this case, the refrigerant circuit must be filled with the amount of refrigerant required to exert the cooling capacity required by the indoor unit in consideration of the amount of refrigerant present in the liquid pipe during the cooling operation. Therefore, there is a problem that the effect of reducing the amount of the refrigerant to be filled in the refrigerant circuit is small even though the liquid pipe is made thin.

本発明は以上述べた問題点を解決するものであって、冷房運転時に室内機で要求される冷房能力を発揮するために必要な量の冷媒を室内機に供給しつつ、冷媒充填量を削減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 reduces the amount of refrigerant charged while supplying the indoor unit with the amount of refrigerant required to exert the cooling capacity required for the indoor unit during cooling operation. The purpose is to provide an air conditioner that can be used.

上記の課題を解決するために、本発明の空気調和機は、冷房運転時に、圧縮機、室外熱交換器、第１膨張弁、気液分離器、室内熱交換器の順で冷媒が循環する冷媒回路と、第２膨張弁を備え気液分離器から圧縮機へと冷媒を導くバイパス管と、第１膨張弁の開度や第２膨張弁の開度を調整する制御手段とを有する。制御手段は、冷房運転を行っているとき、第１膨張弁の開度を、圧縮機から吐出された冷媒の温度である吐出温度が所定の目標温度となるように調整する。そして、制御手段は、冷房運転を行っているとき、第２膨張弁の開度を、第１膨張弁の開度が予め定められた第１所定開度より大きい場合は、現在の開度より大きくし、第１膨張弁の開度が第２所定開度より小さい予め定められた第２所定開度より小さい場合は、現在の開度より小さくする。 In order to solve the above problems, in the air conditioner of the present invention, the refrigerant circulates in the order of the compressor, the outdoor heat exchanger, the first expansion valve, the gas-liquid separator, and the indoor heat exchanger during the cooling operation. It has a refrigerant circuit, a bypass pipe provided with a second expansion valve to guide the refrigerant from the gas-liquid separator to the compressor, and a control means for adjusting the opening degree of the first expansion valve and the opening degree of the second expansion valve. The control means adjusts the opening degree of the first expansion valve so that the discharge temperature, which is the temperature of the refrigerant discharged from the compressor, becomes a predetermined target temperature during the cooling operation. Then, when the control means is performing the cooling operation, the opening degree of the second expansion valve is set to be larger than the current opening degree when the opening degree of the first expansion valve is larger than the predetermined first predetermined opening degree. If the opening degree of the first expansion valve is smaller than the second predetermined opening degree and smaller than the predetermined second predetermined opening degree, the opening degree is made smaller than the current opening degree.

上記のように構成した本発明の空気調和機によれば、冷房運転時に第１膨張弁の開度を吐出温度に基づいて調整し、第２膨張弁の開度を第１膨張弁の開度に基づいて調整する。これにより、冷房運転時に室内機で要求される冷房能力を発揮しつつ、冷媒充填量を削減できる。 According to the air conditioner of the present invention configured as described above, the opening degree of the first expansion valve is adjusted based on the discharge temperature during the cooling operation, and the opening degree of the second expansion valve is adjusted to the opening degree of the first expansion valve. Adjust based on. As a result, it is possible to reduce the amount of refrigerant charged while exhibiting the cooling capacity required for the indoor unit during the cooling 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）は室外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 outdoor unit control means. 本発明の実施形態における、冷房運転時の処理の流れを示すフローチャートである。It is a flowchart which shows the flow of the process 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、１台の室外機と１台の室内機が２本の冷媒配管で接続された空気調和機を例に挙げて説明する。なお、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 one outdoor unit and one indoor unit are connected by two refrigerant pipes 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、室内に設置され室外機２に液管４およびガス管５で接続された室内機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。以上により、空気調和機１の冷媒回路１０が形成されている。なお、本実施形態の空気調和機１では、冷媒回路１０に充填する冷媒量を削減するために、液管４が細くされている。例えば、空気調和装置１の冷房運転時の定格能力が１０ｋＷである場合は、通常は液管４の内径が９．５ｍｍであるのに対し、本実施形態では６．４ｍｍとする。 As shown in FIG. 1A, the air conditioner 1 in this embodiment has an outdoor unit 2 installed outdoors and an indoor unit installed indoors and connected to the outdoor unit 2 by a liquid pipe 4 and a gas pipe 5. It is equipped with a machine 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. As described above, the refrigerant circuit 10 of the air conditioner 1 is formed. In the air conditioner 1 of the present embodiment, the liquid pipe 4 is made thinner in order to reduce the amount of the refrigerant to be filled in the refrigerant circuit 10. For example, when the rated capacity of the air conditioner 1 during the cooling operation is 10 kW, the inner diameter of the liquid pipe 4 is usually 9.5 mm, whereas in the present embodiment it is 6.4 mm.

＜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、室外ファン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、第１膨張弁２７ａと、第２膨張弁２７ｂと、気液分離器２８と、開閉弁２９と、第１逆止弁３０ａと、第２逆止弁３０ｂとを備えている。そして、室外ファン２４を除くこれら各装置が以下で詳述する各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. The outdoor unit 2 was connected to a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, an outdoor fan 24, a closing valve 25 to which one end of the liquid pipe 4 was connected, and one end of the gas pipe 5. It includes a closing valve 26, a first expansion valve 27a, a second expansion valve 27b, a gas-liquid separator 28, an on-off valve 29, a first check valve 30a, and a second check valve 30b. .. Each of these devices except the outdoor fan 24 is connected to each other by the refrigerant pipes described in detail below to form the outdoor unit refrigerant circuit 10a forming a part of the refrigerant circuit 10.

圧縮機２１は、図示しないインバータにより回転数が制御されることで、運転容量を変えることができる容量可変型圧縮機である。圧縮機２１の冷媒吐出側と四方弁２２のポートａとが、吐出管６１で接続されている。また、圧縮機２１の冷媒吸入側と四方弁２２のポートｃとが、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 controlling the rotation speed by an inverter (not shown). The refrigerant discharge side of the compressor 21 and the port a of the four-way valve 22 are connected by a discharge pipe 61. Further, the refrigerant suction side of the compressor 21 and the port c of the four-way valve 22 are connected by a suction pipe 66.

四方弁２２は、冷媒の流れる方向を切り替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、上述したように圧縮機２１の冷媒吸入側と吸入管６６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 / outlets of the outdoor heat exchanger 23 by a refrigerant pipe 62. As described above, the port c is connected to the refrigerant suction side of the compressor 21 by a suction pipe 66. 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、後述する室外ファン２４の回転により室外機２の内部に取り込まれた外気と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、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が冷房運転を行う場合は凝縮器として機能し、暖房運転を行う場合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 inside of the outdoor unit 2 by the rotation of the outdoor fan 24 described later. As described above, one refrigerant inlet / outlet of the outdoor heat exchanger 23 is connected to the port b of the four-way valve 22 by the refrigerant pipe 62, and the other refrigerant inlet / outlet is connected to the closing valve 25 by the 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.

第１膨張弁２７ａは、例えば電子膨張弁であり、室外機液管６３に設けられている。第１膨張弁２７ａの開度が調整されることで、室内機３を流れる冷媒量が調整される。なお、第１膨張弁２７ａの具体的な開度の調整方法については、後述する。 The first expansion valve 27a is, for example, an electronic expansion valve, and is provided in the outdoor unit liquid pipe 63. By adjusting the opening degree of the first expansion valve 27a, the amount of refrigerant flowing through the indoor unit 3 is adjusted. A specific method for adjusting the opening degree of the first expansion valve 27a will be described later.

室外ファン２４は樹脂材で形成されており、室外熱交換器２３の近傍に配置されている。室外ファン２４は、図示しないファンモータ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の内部へ外気を取り込み、室外熱交換器２３において冷媒と熱交換した外気を室外機２の図示しない吹出口から室外機２外部へ放出する。 The outdoor fan 24 is made of a resin material and is arranged in the vicinity of the outdoor heat exchanger 23. The outdoor fan 24 is rotated by a fan motor (not shown) to take in outside air from a suction port (not shown) into the outdoor unit 2 and exchange heat with the refrigerant in the outdoor heat exchanger 23 to be exchanged with the refrigerant in the outdoor unit 2. It is discharged to the outside of the outdoor unit 2 from an outlet (not shown).

気液分離器２８は、略円筒形状の密閉容器であり、流入した気液二相冷媒をガス冷媒と液冷媒とに分離するものである。気液分離器２８の密閉容器の天面に設けられた冷媒流入口と、室外機液管６３における第１膨張弁２７ａと閉鎖弁２５の間とが第１液分管６７で接続されており、冷房運転時に第１液分管６７から気液分離器２８の内部に気液二相冷媒が流入する。また、気液分離器２８の密閉容器の側面下方に設けられた液冷媒流出口と、室外機液管６３における第１液分管６７の接続部と閉鎖弁２５の間とが第２液分管６８で接続されており、気液分離器２８で分離されて密閉容器の底部に溜まった液冷媒が第２液分管６８へと流出する。そして、気液分離器２８の底面に設けられたガス冷媒流出口と吸入管６６とがバイパス菅６９で接続されており、気液分離器２８で分離されたガス冷媒がバイパス管６９へと流出する。なお、バイパス管６９の一部はガス冷媒流出口を通して気液分離器２８の内部に挿入されており、バイパス管６９の気液分離器２８の内部に開口する端部は、液冷媒流出口よりも高い位置に配置される。 The gas-liquid separator 28 is a closed container having a substantially cylindrical shape, and separates the inflowing gas-liquid two-phase refrigerant into a gas refrigerant and a liquid refrigerant. The refrigerant inlet provided on the top surface of the closed container of the gas-liquid separator 28 and the space between the first expansion valve 27a and the closing valve 25 in the outdoor unit liquid pipe 63 are connected by the first liquid branch pipe 67. During the cooling operation, the gas-liquid two-phase refrigerant flows from the first liquid branch pipe 67 into the gas-liquid separator 28. Further, the liquid refrigerant outlet provided below the side surface of the closed container of the gas-liquid separator 28 and the connection portion of the first liquid branch pipe 67 in the outdoor unit liquid pipe 63 and the closing valve 25 are between the second liquid branch pipe 68. The liquid refrigerant separated by the gas-liquid separator 28 and accumulated at the bottom of the closed container flows out to the second liquid branch pipe 68. The gas refrigerant outlet provided on the bottom surface of the gas-liquid separator 28 and the suction pipe 66 are connected by a bypass pipe 69, and the gas refrigerant separated by the gas-liquid separator 28 flows out to the bypass pipe 69. do. A part of the bypass pipe 69 is inserted into the gas-liquid separator 28 through the gas refrigerant outlet, and the end of the bypass pipe 69 that opens inside the gas-liquid separator 28 is from the liquid refrigerant outlet. Is also placed in a high position.

開閉弁２９は、第１液分管６７に設けられている。開閉弁２９は、冷房運転時は開かれ、暖房運転時は閉じられる。第１逆止弁３０ａは、室外機液管６３における第１液分管６７の接続部と第２液分管６８の接続部との間に設けられており、室外機液管６３を閉鎖弁２５から第１膨張弁２７ａに向かう方向にのみ冷媒が流れるようにするものである。第２逆止弁３０ｂは、第２液分管６８に設けられており、第２液分管６８を気液分離器２８から室外機液管６３に向かう方向にのみ冷媒が流れるようにするものである。 The on-off valve 29 is provided in the first liquid branch pipe 67. The on-off valve 29 is opened during the cooling operation and closed during the heating operation. The first check valve 30a is provided between the connection portion of the first liquid branch pipe 67 and the connection portion of the second liquid branch pipe 68 in the outdoor unit liquid pipe 63, and the outdoor unit liquid pipe 63 is connected from the closing valve 25. The refrigerant flows only in the direction toward the first expansion valve 27a. The second check valve 30b is provided in the second liquid branch pipe 68, and allows the refrigerant to flow only in the direction from the gas / liquid separator 28 toward the outdoor unit liquid pipe 63. ..

第２膨張弁２７ｂは例えば電子膨張弁であり、バイパス管６９における気液分離器２８のガス冷媒流出口の近傍に設けられている。第２膨張弁２７ｂの開度が調整されることで、気液分離器２８から吸入管６６へと流れるガス冷媒の量が調整される。第２膨張弁２７ｂの具体的な開度の調整方法については、後述する。 The second expansion valve 27b is, for example, an electronic expansion valve, and is provided in the vicinity of the gas refrigerant outlet of the gas-liquid separator 28 in the bypass pipe 69. By adjusting the opening degree of the second expansion valve 27b, the amount of gas refrigerant flowing from the gas-liquid separator 28 to the suction pipe 66 is adjusted. A specific method for adjusting the opening degree of the second expansion valve 27b will be described later.

以上説明した構成の他に、室外機２には各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。吸入管６６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 various sensors. 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. The suction pipe 66 is provided with 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.

室外熱交換器２３の図示しない冷媒流路の中間部には、冷媒流路の中間部を流れる冷媒の温度、すなわち室外熱交換器２３の温度を検出するための熱交温度センサ７５が設けられている。室外機２の図示しない吸込口付近には、室外機２の内部に流入する外気の温度、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 heat exchange temperature sensor 75 for detecting the temperature of the refrigerant flowing in the middle portion of the refrigerant flow path, that is, the temperature of the outdoor heat exchanger 23, is provided in the middle portion of the refrigerant flow path (not shown) of the outdoor heat exchanger 23. ing. An outside air temperature sensor 76 for detecting the temperature of the outside air flowing 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. 1 (B), 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、各室内機５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等を含む）や室外機２の定格能力および各室内機５の要求能力を記憶する。通信部２３０は、各室内機５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 is transmitted from the control program of the outdoor unit 2, the detection value corresponding to the detection signal from various sensors, the drive state of the compressor 21 and the outdoor unit fan 28, and each indoor unit 5. It stores operation information (including operation / stop information, operation modes such as cooling / heating, etc.), the rated capacity of the outdoor unit 2, and the required capacity of each indoor unit 5. The communication unit 230 is an interface for communicating with each indoor unit 5. 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、各室内機５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、第１膨張弁２４ａや第２膨張弁２４ｂの開度調整、圧縮機２１や室外機ファン２８の駆動制御を行う。 The CPU 210 periodically (for example, every 30 seconds) captures the detection values of various sensors via the sensor input unit 240, and a signal including operation information transmitted from each indoor unit 5 is transmitted via the communication unit 230. Entered. The CPU 210 adjusts the opening degree of the first expansion valve 24a and the second expansion valve 24b, and controls the drive of the compressor 21 and the outdoor unit fan 28 based on the various input information.

＜室内機の構成＞
次に、図１（Ａ）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、室内ファン３２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を備えている。そして、室内ファン３２を除くこれら各装置が以下で詳述する各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を構成している。 <Composition of indoor unit>
Next, the indoor unit 3 will be described with reference to FIG. 1 (A). The indoor unit 3 has an indoor heat exchanger 31, an indoor fan 32, a liquid pipe connecting portion 33 to which the other end of the liquid pipe 4 is connected, and a gas pipe connecting portion 34 to which the other end of the gas pipe 5 is connected. I have. Each of these devices except the indoor fan 32 is connected to each other by each refrigerant pipe described in detail below to form an indoor unit refrigerant circuit 10b that forms a part of the refrigerant circuit 10.

室内熱交換器３１は、冷媒と、後述する室内ファン３２の回転により室内機３の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とを熱交換させるものであり、一方の冷媒出入口が液管接続部３３と室内機液管９１で接続され、他方の冷媒出入口がガス管接続部３４と室内機ガス管９２で接続されている。室内熱交換器３１は、空気調和機１が冷房運転を行う場合は蒸発器として機能し、暖房運転を行う場合は凝縮器として機能する。なお、液管接続部３３やガス管接続部３４では、各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 indoor unit 3 from a suction port (not shown) of the indoor unit 3 by the rotation of the indoor fan 32 described later, and one of the refrigerants. The inlet / outlet is connected to the liquid pipe connecting portion 33 by the indoor unit liquid pipe 91, and the other refrigerant inlet / outlet is connected to the gas pipe connecting portion 34 by the indoor unit gas pipe 92. The indoor heat exchanger 31 functions as an evaporator when the air conditioner 1 performs a cooling operation, and functions as a condenser when the air conditioner 1 performs a heating operation. In the liquid pipe connecting portion 33 and the gas pipe connecting portion 34, each refrigerant pipe is connected by welding, flare nut, or the like.

室内ファン３２は樹脂材で形成されており、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、室内機３の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室内機３の図示しない吹出口から室内へ吹き出す。 The indoor fan 32 is 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) of the indoor unit 3, and to exchange heat with the refrigerant in the indoor heat exchanger 31 into the room. Blow into the room from an outlet (not shown) of the machine 3.

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９１には、室内熱交換器３１に流入あるいは室内熱交換器３１から流出する冷媒の温度を検出する液側温度センサ８１が設けられている。室内機ガス管９２には、室内熱交換器３１から流出あるいは室内熱交換器３１に流入する冷媒の温度を検出するガス側温度センサ８２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、すなわち室温を検出する室温センサ８３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 91 is provided with a liquid side temperature sensor 81 for detecting the temperature of the refrigerant flowing into the indoor heat exchanger 31 or flowing out from the indoor heat exchanger 31. The indoor unit gas pipe 92 is provided with a gas side temperature sensor 82 that detects the temperature of the refrigerant flowing out of the indoor heat exchanger 31 or flowing into the indoor heat exchanger 31. A room temperature sensor 83 for detecting the temperature of the indoor air flowing into the indoor unit 3, that is, the room temperature, is provided in the vicinity of the suction port (not shown) of the indoor unit 3.

＜冷媒回路の動作＞
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部の動作について説明する。以下の説明では、まず、図１（Ａ）を用いて、空気調和機１が暖房運転を行う場合について説明し、次に、空気調和機１が冷房運転を行う場合について説明する。 <Operation of refrigerant circuit>
Next, the flow of the refrigerant in the refrigerant circuit 10 during the air conditioning operation of the air conditioner 1 in the present embodiment and the operation of each part will be described. In the following description, first, the case where the air conditioner 1 performs the heating operation will be described with reference to FIG. 1A, and then the case where the air conditioner 1 performs the cooling operation will be described.

＜暖房運転時の冷媒回路の動作＞
空気調和機１が暖房運転を行う場合、冷媒回路１０は、図１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とが連通するよう、また、ポートｂとポートｃ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暖房サイクルとなる。なお、前述したように、開閉弁２９は暖房運転時は閉じられている。また、第２膨張弁２７ｂの開度は全開とされている。 <Operation of refrigerant circuit during heating operation>
When the air conditioner 1 performs the heating operation, the refrigerant circuit 10 has a state in which the four-way valve 22 is shown by a broken line as shown in FIG. 1, that is, the port a and the port d of the four-way valve 22 communicate with each other. The port b and the 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, and the outdoor heat exchanger 23 functions as an evaporator and the indoor heat exchanger 31 functions as a condenser. As described above, the on-off valve 29 is closed during the heating operation. Further, the opening degree of the second expansion valve 27b is fully opened.

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を流れ閉鎖弁２６を介してガス管５に流出する。ガス管５を流れる冷媒は、ガス管接続部３４を介して室内機３に流入する。 The high-pressure refrigerant discharged from the compressor 21 flows through the discharge pipe 61, flows into the four-way valve 22, flows from the four-way valve 22 through the outdoor unit gas pipe 64, and flows out to the gas pipe 5 via the closing valve 26. The refrigerant flowing through the gas pipe 5 flows into the indoor unit 3 via the gas pipe connecting portion 34.

室内機３に流入した冷媒は、室内機ガス管９２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 refrigerant that has flowed into the indoor unit 3 flows through the indoor unit gas pipe 92 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. do. In this way, the indoor heat exchanger 31 functions as a condenser, and the indoor unit 3 is installed by blowing out the indoor air that has exchanged heat with the refrigerant in the indoor heat exchanger 31 into the room from an outlet (not shown). The room is heated.

室内熱交換器３１から流出した冷媒は室内機液管９１を流れ、液管接続部３３を介して液管４に流出する。液管４を流れ閉鎖弁２５を介して室外機２に流入した冷媒は、室外機液管６３を流れ第１逆止弁３０ａを介して第１膨張弁２７ａへと流れ、第１膨張弁２７ａを通過する際に減圧される。このとき、第２逆止弁３０ｂにより、液管４から室外機液管６３に流入した冷媒は、第２液分管６８には流れない。また、開閉弁２９が閉じられていることにより、液管４から室外機液管６３に流出した冷媒は、第１液分管６７には流れない。 The refrigerant flowing out of the indoor heat exchanger 31 flows through the indoor unit liquid pipe 91 and flows out to the liquid pipe 4 via the liquid pipe connecting portion 33. The refrigerant flowing through the liquid pipe 4 and flowing into the outdoor unit 2 through the closing valve 25 flows through the outdoor unit liquid pipe 63 and flows to the first expansion valve 27a via the first check valve 30a, and flows to the first expansion valve 27a. The pressure is reduced as it passes through. At this time, the refrigerant flowing into the outdoor unit liquid pipe 63 from the liquid pipe 4 by the second check valve 30b does not flow into the second liquid branch pipe 68. Further, since the on-off valve 29 is closed, the refrigerant flowing out from the liquid pipe 4 to the outdoor unit liquid pipe 63 does not flow into the first liquid branch pipe 67.

第１膨張弁２７ａは、吐出温度センサ７３で検出した吐出温度が、外気温度や室内機３で要求される暖房能力に応じて予め定められている目標温度となるように開度が調整されている。具体的には、検出した吐出温度が目標温度より高い場合は、第１膨張弁２７ａの開度が現在の開度より大きくされる。第１膨張弁２７ａの開度が大きくされることで、冷媒回路１０から圧縮機２１に戻る冷媒量が多くなって吐出温度が低下する。一方、検出した吐出温度が目標温度より低い場合は、第１膨張弁２７ａの開度が現在の開度より小さくされる。第１膨張弁２７ａの開度が小さくされることで、冷媒回路１０から圧縮機２１に戻る冷媒量が少なくなって圧縮機２１の内部温度が上昇するので、吐出温度が上昇する。第１膨張弁２７ａを通過する際に減圧された冷媒は、室外機液管６３を流れて室外熱交換器２３に流入し、室外熱交換器２３で室外ファン２４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蒸発する。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、吸入管６６を流れ、圧縮機２１に吸入されて再び圧縮される。 The opening degree of the first expansion valve 27a is adjusted so that the discharge temperature detected by the discharge temperature sensor 73 becomes a predetermined target temperature according to the outside air temperature and the heating capacity required by the indoor unit 3. There is. Specifically, when the detected discharge temperature is higher than the target temperature, the opening degree of the first expansion valve 27a is made larger than the current opening degree. By increasing the opening degree of the first expansion valve 27a, the amount of refrigerant returning from the refrigerant circuit 10 to the compressor 21 increases, and the discharge temperature decreases. On the other hand, when the detected discharge temperature is lower than the target temperature, the opening degree of the first expansion valve 27a is made smaller than the current opening degree. By reducing the opening degree of the first expansion valve 27a, the amount of refrigerant returning from the refrigerant circuit 10 to the compressor 21 decreases, and the internal temperature of the compressor 21 rises, so that the discharge temperature rises. The refrigerant decompressed when passing through the first expansion valve 27a flows through the outdoor unit liquid pipe 63 and flows into the outdoor heat exchanger 23, and the inside of the outdoor unit 2 is rotated by the rotation of the outdoor fan 24 in the outdoor heat exchanger 23. It evaporates by exchanging heat with the outside air taken into the air. The refrigerant flowing out from the outdoor heat exchanger 23 to the refrigerant pipe 62 flows through the four-way valve 22 and the suction pipe 66, is sucked into the compressor 21, and is compressed again.

＜冷房運転時の冷媒回路の動作＞
空気調和機１が冷房運転を行う場合、冷媒回路１０は、図１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暖房サイクルとなる。なお、前述したように、開閉弁２９は冷房運転時は開かれている。 <Operation of refrigerant circuit during cooling operation>
When the air conditioner 1 performs the cooling operation, the refrigerant circuit 10 is in a state where the four-way valve 22 is shown by a solid line as shown in FIG. 1, that is, the port a and the port b of the four-way valve 22 communicate with each other. The port c and the port d are switched so as to communicate with each other. As a result, the refrigerant circulates in the direction indicated by the solid line 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. As described above, the on-off valve 29 is open during the cooling operation.

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２４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 24 and condenses.

室外熱交換器２３から室外機液管６３に流出した冷媒は、第１膨張弁２７ａを通過する際に減圧される。第１膨張弁２７ａの開度は、吐出温度センサ７３で検出した吐出温度が、外気温度や室内機３で要求される冷房能力に応じて予め定められている目標温度となるように開度が調整されている。なお、具体的な第１膨張弁２７ａの開度調整方法については、暖房運転の際に説明した方法と同じであるため、詳細な説明は省略する。また、第１膨張弁２７ａの開度により、室外熱交換器２３から流出する冷媒は、ガス冷媒と液冷媒とが混合された気液二相冷媒となる。 The refrigerant flowing out from the outdoor heat exchanger 23 to the outdoor unit liquid pipe 63 is depressurized when passing through the first expansion valve 27a. The opening degree of the first expansion valve 27a is such that the discharge temperature detected by the discharge temperature sensor 73 becomes a target temperature predetermined according to the outside air temperature and the cooling capacity required by the indoor unit 3. It has been adjusted. Since the specific method for adjusting the opening degree of the first expansion valve 27a is the same as the method described during the heating operation, detailed description thereof will be omitted. Further, the refrigerant flowing out from the outdoor heat exchanger 23 due to the opening degree of the first expansion valve 27a becomes a gas-liquid two-phase refrigerant in which a gas refrigerant and a liquid refrigerant are mixed.

第１膨張弁２７ａを通過した冷媒は、第１逆止弁３０ａによって閉鎖弁２５側へ流れないこと、および、開閉弁６７が開かれていることによって第１液分管６７へと流れ、気液分離器２８に流入する。このとき、気液分離器２８に流入した冷媒は気液分離器２８の内部で液冷媒とガス冷媒とに分離される。 The refrigerant that has passed through the first expansion valve 27a does not flow to the closing valve 25 side by the first check valve 30a, and flows to the first liquid branch pipe 67 due to the opening of the on-off valve 67. It flows into the separator 28. At this time, the refrigerant flowing into the gas-liquid separator 28 is separated into a liquid refrigerant and a gas refrigerant inside the gas-liquid separator 28.

気液分離器２８の内部に滞留するガス冷媒はバイパス管６９へと流出し、第１膨張弁２７ａの開度に応じた開度とされている第２膨張弁２７ｂ（開度調整の詳細については、後述する）を通過する際に減圧されて、吸入管６６へと流れる。一方、気液分離器２８の内部に滞留する液冷媒は第２液分管６８へと流出し、第２逆止弁３０ｂを介して室外機液管６３へと流れる。 The gas refrigerant staying inside the gas-liquid separator 28 flows out to the bypass pipe 69, and the opening of the second expansion valve 27b is set according to the opening of the first expansion valve 27a (details of opening adjustment). Is decompressed as it passes through (described later) and flows to the suction pipe 66. On the other hand, the liquid refrigerant staying inside the gas-liquid separator 28 flows out to the second liquid branch pipe 68 and flows to the outdoor unit liquid pipe 63 via the second check valve 30b.

室外機液管６３を流れ閉鎖弁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９１を流れて室内熱交換器３１に流入する。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。 It flows through the outdoor unit liquid pipe 63 and flows out to the liquid pipe 4 through the closing valve 25. The refrigerant flowing through the liquid pipe 4 and flowing into the indoor unit 3 through the liquid pipe connecting portion 33 flows through the indoor unit liquid pipe 91 and flows into the indoor heat exchanger 31. 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 unit 3 is installed by blowing out the indoor air that has exchanged heat with the refrigerant in the indoor heat exchanger 31 into the room from an outlet (not shown). 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９２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を流れて閉鎖弁２６を介して室外機２に流入した冷媒は、室外機ガス管６４、四方弁２２、吸入管６６を流れ、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 92 and flows out to the gas pipe 5 via the gas pipe connecting portion 34. The refrigerant that has flowed through the gas pipe 5 and has flowed into the outdoor unit 2 through the closing valve 26 flows through the outdoor unit gas pipe 64, the four-way valve 22, and the suction pipe 66, is sucked into the compressor 21, and is compressed again.

＜第２膨張弁の開度調整＞
前述したように、冷房運転時の第２膨張弁２７ｂの開度は、第１膨張弁２７ａの開度に応じた開度とされる。具体的には、第１膨張弁２７ａの開度が予め定められた第１所定開度以上である場合は、第２膨張弁２７ｂの開度を現在の開度より大きくする。一方、第１膨張弁２７ａの開度が、第１所定開度よりも小さい予め定められた第２所定開度以下である場合は、第２膨張弁２７ｂの開度を現在の開度より小さくする。なお、第１膨張弁２７ａの開度が第１所定開度よりも小さく、かつ、第２所定開度よりも大きい場合は、現在の第２膨張弁２７ｂの開度を維持する。 <Adjusting the opening of the second expansion valve>
As described above, the opening degree of the second expansion valve 27b during the cooling operation is set to the opening degree corresponding to the opening degree of the first expansion valve 27a. Specifically, when the opening degree of the first expansion valve 27a is equal to or larger than a predetermined first predetermined opening degree, the opening degree of the second expansion valve 27b is made larger than the current opening degree. On the other hand, when the opening degree of the first expansion valve 27a is smaller than the first predetermined opening degree and is equal to or less than the predetermined second predetermined opening degree, the opening degree of the second expansion valve 27b is made smaller than the current opening degree. do. When the opening degree of the first expansion valve 27a is smaller than the first predetermined opening degree and larger than the second predetermined opening degree, the current opening degree of the second expansion valve 27b is maintained.

以下、第２膨張弁２７ｂの開度を第１膨張弁２７ａの開度に応じて調整する方法とその効果について説明する。まず、第１膨張弁２７ａの開度が第１所定開度より大きい場合の第２膨張弁２７ｂの開度調整の方法とその効果について説明し、次に、第１膨張弁２７ａの開度が第２所定開度より小さい場合の第２膨張弁２７ｂの開度調整の方法とその効果について説明する。 Hereinafter, a method of adjusting the opening degree of the second expansion valve 27b according to the opening degree of the first expansion valve 27a and its effect will be described. First, a method of adjusting the opening degree of the second expansion valve 27b and its effect when the opening degree of the first expansion valve 27a is larger than the first predetermined opening degree will be described, and then the opening degree of the first expansion valve 27a will be described. A method of adjusting the opening degree of the second expansion valve 27b when the opening degree is smaller than the second predetermined opening degree and its effect will be described.

＜第１膨張弁の開度が第１所定開度より大きい場合＞
前述したように、冷房運転時の第１膨張弁２７ａの開度は、吐出温度センサ７３で検出した吐出温度が予め定められている目標温度となるように開度が調整されており、検出した吐出温度が目標温度より高い場合は、第１膨張弁２７ａの開度が現在の開度より大きくされる。 <When the opening of the first expansion valve is larger than the first predetermined opening>
As described above, the opening degree of the first expansion valve 27a during the cooling operation is detected by adjusting the opening degree so that the discharge temperature detected by the discharge temperature sensor 73 becomes a predetermined target temperature. When the discharge temperature is higher than the target temperature, the opening degree of the first expansion valve 27a is made larger than the current opening degree.

本実施形態の空気調和機１のように、冷媒回路１０に充填する冷媒量を削減するために液管４を細くしている場合は、液管４が太い場合と比べて冷媒が液管４を流れる際に受ける圧力損失が大きくなる。このため、冷媒回路１０における冷媒循環量が少なくなって吐出温度が上昇し、第１膨張弁２７ａの開度を大きくして全開としても吐出温度を下げて目標温度とすることができなくなる場合がある。 When the liquid pipe 4 is thinned in order to reduce the amount of the refrigerant charged in the refrigerant circuit 10 as in the air conditioner 1 of the present embodiment, the refrigerant is the liquid pipe 4 as compared with the case where the liquid pipe 4 is thick. The pressure loss received when flowing through the air conditioner increases. Therefore, the amount of refrigerant circulation in the refrigerant circuit 10 decreases and the discharge temperature rises, and even if the opening degree of the first expansion valve 27a is increased and the first expansion valve 27a is fully opened, the discharge temperature may not be lowered to reach the target temperature. be.

そこで、本実施形態の空気調和機１では、第１膨張弁２７ａの開度が予め定められた第１所定開度以上である場合は、第２膨張弁２７ｂの開度を現在の開度より大きくする。ここで、第１所定開度とは、第１膨張弁２７ａの最大開度より少し小さい開度であり、第１膨張弁２７ａの開度が第１所定開度より大きいときは、液管４を流れる際の圧力損失が大きくなっていることに起因して吐出温度が下がりにくい状態となっていることが、予め行った試験などによって判明している第１膨張弁２７ａの開度である。なお、一例として、第１膨張弁２７ａが最大開度であるときに第１膨張弁２７ａの図示しないステッピングモータに加えられるパルス数を５００パルスとしたとき、第１所定開度とするために第１膨張弁２７ａに加えられるパルス数は、４００パルスである。 Therefore, in the air conditioner 1 of the present embodiment, when the opening degree of the first expansion valve 27a is equal to or larger than the predetermined first predetermined opening degree, the opening degree of the second expansion valve 27b is set from the current opening degree. Enlarge. Here, the first predetermined opening is an opening slightly smaller than the maximum opening of the first expansion valve 27a, and when the opening of the first expansion valve 27a is larger than the first predetermined opening, the liquid pipe 4 It is the opening degree of the first expansion valve 27a that has been found by a test or the like conducted in advance that the discharge temperature is difficult to decrease due to the large pressure loss when flowing through the water. As an example, when the number of pulses applied to the stepping motor (not shown) of the first expansion valve 27a is 500 when the first expansion valve 27a has the maximum opening, the first predetermined opening is set. The number of pulses applied to one expansion valve 27a is 400 pulses.

第１膨張弁２７ａの開度が第１所定開度以上である場合に第２膨張弁２７ｂの開度を現在の開度より大きくすると、第２膨張弁２７ｂの開度が小さい場合と比べて気液分離器２８に滞留するガス冷媒がバイパス管６９へと流出する量が増加する。このため、気液分離器２８から第２液分管６８に流出する液冷媒に対するガス冷媒の割合が少なくなって、第２液分管６８から液管４へと流れる冷媒の密度が高くなる。そして、液管４を流れる冷媒の密度が高くなれば、冷媒が液管４を流れる際の圧力損失が冷媒の密度が低い場合と比べて小さくなるので、冷媒回路１０における冷媒循環量が多くなって吐出温度が低下する。 When the opening degree of the first expansion valve 27a is larger than the current opening degree when the opening degree of the first expansion valve 27a is equal to or larger than the first predetermined opening degree, the opening degree of the second expansion valve 27b is smaller than that of the second expansion valve 27b. The amount of the gas refrigerant staying in the gas-liquid separator 28 flowing out to the bypass pipe 69 increases. Therefore, the ratio of the gas refrigerant to the liquid refrigerant flowing out from the gas-liquid separator 28 to the second liquid dividing pipe 68 becomes small, and the density of the refrigerant flowing from the second liquid dividing pipe 68 to the liquid pipe 4 becomes high. When the density of the refrigerant flowing through the liquid pipe 4 becomes high, the pressure loss when the refrigerant flows through the liquid pipe 4 becomes smaller than when the density of the refrigerant is low, so that the amount of refrigerant circulation in the refrigerant circuit 10 increases. The discharge temperature drops.

＜第１膨張弁の開度が第２所定開度より小さい場合＞
上述したように、第１膨張弁２７ａの開度が第１所定開度以上となっているときに、第２膨張弁２７ｂの開度を大きくして第２液分管６８から液管４へと流れる冷媒の密度を高くすることで、吐出温度は低下する。そして、検出した吐出温度が目標温度より低くなった場合は、第１膨張弁２７ａの開度が現在の開度より小さくされる。このとき、第１膨張弁２７ａの開度が第１所定開度より小さくなったことによって第２膨張弁２７ｂの開度を小さくすれば、第１膨張弁２７ａの開度が第１所定開度を境として大きくなったり小さくなったりを繰り返し、これに応じて第２膨張弁２７ｂの開度も大きくなったり小さくなったりを繰り返す、所謂ハンチングを起こす恐れがある。 <When the opening of the first expansion valve is smaller than the second predetermined opening>
As described above, when the opening degree of the first expansion valve 27a is equal to or larger than the first predetermined opening degree, the opening degree of the second expansion valve 27b is increased from the second liquid branch pipe 68 to the liquid pipe 4. By increasing the density of the flowing refrigerant, the discharge temperature decreases. When the detected discharge temperature becomes lower than the target temperature, the opening degree of the first expansion valve 27a is made smaller than the current opening degree. At this time, if the opening degree of the second expansion valve 27b is reduced because the opening degree of the first expansion valve 27a is smaller than the first predetermined opening degree, the opening degree of the first expansion valve 27a becomes the first predetermined opening degree. There is a risk of causing so-called hunting, in which the opening of the second expansion valve 27b is repeatedly increased and decreased in response to the repeated increase and decrease in size.

そこで、本実施形態の空気調和機１では、第１膨張弁２７ａの開度が予め定められた第２所定開度以下である場合に、第２膨張弁２７ｂの開度を現在の開度より小さくする。ここで、第２所定開度は、第１所定開度より小さい開度であり、例えば３５０パルスである。なお、この第２所定開度は、室内機３で発揮される冷房能力を考慮して決定される。第１膨張弁２７ａの開度が第２所定開度以下であるときに第２膨張弁２７ｂの開度が大きくされていると、液管４を流れる冷媒における液冷媒に対するガス冷媒の割合が低くなって液管４を流れる冷媒の密度が高くなることに起因して、室内熱交換器３１における蒸発能力が低下して室内機３で発揮される冷房能力が低下する恐れがある。そこで、本実施形態では、上述した冷房能力の低下を抑制しつつ、第２膨張弁２７ｂの開度調整のハンチングを防ぐことができるように、第２所定開度が定められる。 Therefore, in the air conditioner 1 of the present embodiment, when the opening degree of the first expansion valve 27a is equal to or less than a predetermined second predetermined opening degree, the opening degree of the second expansion valve 27b is set from the current opening degree. Make it smaller. Here, the second predetermined opening degree is an opening degree smaller than the first predetermined opening degree, and is, for example, 350 pulses. The second predetermined opening degree is determined in consideration of the cooling capacity exerted by the indoor unit 3. If the opening degree of the second expansion valve 27b is increased when the opening degree of the first expansion valve 27a is equal to or less than the second predetermined opening degree, the ratio of the gas refrigerant to the liquid refrigerant in the refrigerant flowing through the liquid pipe 4 is low. As a result, the density of the refrigerant flowing through the liquid pipe 4 becomes high, so that the evaporation capacity of the indoor heat exchanger 31 may decrease and the cooling capacity exhibited by the indoor unit 3 may decrease. Therefore, in the present embodiment, the second predetermined opening degree is determined so as to prevent the hunting of the opening degree adjustment of the second expansion valve 27b while suppressing the above-mentioned decrease in the cooling capacity.

以上説明したように、本実施形態の空気調和機１では、第１膨張弁２７ａの開度が第１所定開度より大きいときは、第２膨張弁２７ｂの開度を現在の開度より大きくして液側配管を流れる冷媒の密度を高くする。一方、第１膨張弁２７ａの開度が第２所定開度より小さいときは、第２膨張弁２７ｂの開度を現在の開度より小さくして液管４を流れる冷媒の密度を小さくする。これにより、液管４を細くして冷媒回路１０に充填する冷媒量を削減しても、冷房運転時に冷媒循環量を確保して要求される冷房能力を発揮させつつ、吐出温度が高い場合はこれを確実に低下させることができる。なお、第２膨張弁２７ｂの開度調整は、予め定められた所定の開度増減値ずつ、例えば第２膨張弁２７ｂに加えるパルス数を５０パルスずつ増減すればよい。 As described above, in the air conditioner 1 of the present embodiment, when the opening degree of the first expansion valve 27a is larger than the first predetermined opening degree, the opening degree of the second expansion valve 27b is made larger than the current opening degree. The density of the refrigerant flowing through the liquid side piping is increased. On the other hand, when the opening degree of the first expansion valve 27a is smaller than the second predetermined opening degree, the opening degree of the second expansion valve 27b is made smaller than the current opening degree to reduce the density of the refrigerant flowing through the liquid pipe 4. As a result, even if the liquid pipe 4 is thinned to reduce the amount of refrigerant to be filled in the refrigerant circuit 10, the amount of refrigerant circulation is secured during the cooling operation and the required cooling capacity is exhibited, and the discharge temperature is high. This can be reliably reduced. The opening degree of the second expansion valve 27b may be adjusted by increasing or decreasing the predetermined opening degree increase / decrease value, for example, the number of pulses applied to the second expansion valve 27b by 50 pulses.

＜冷房運転時の第２膨張弁の開度調整に関わる処理の流れ＞
次に、図３を用いて、冷房運転時の第１膨張弁２７ａおよび第２膨張弁２７ｂ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、冷房運転時の第１膨張弁２７ａおよび第２膨張弁２７ｂの開度調整において、室外機制御手段２００のＣＰＵ２１０が行う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。 <Flow of processing related to adjusting the opening of the second expansion valve during cooling operation>
Next, with reference to FIG. 3, a process related to adjusting the opening degree of the first expansion valve 27a and the second expansion valve 27b during the cooling operation will be described. FIG. 3 is a flowchart showing a flow of processing performed by the CPU 210 of the outdoor unit control means 200 in adjusting the opening degree of the first expansion valve 27a and the second expansion valve 27b during the cooling operation. In the flowchart of FIG. 3, ST represents a step of processing, and the number following it represents the number of the step.

また、図３のフローチャートでは、第１膨張弁２７ａの開度をＰｅ１、第２膨張弁２７ｂの開度をＰｅ２、第１膨張弁２７ａの冷房運転開始時の初期開度をＰｅｄ、第１所定開度をＰｅｔ１、第２所定開度をＰｅｔ２、第２膨張弁２７ｂの最小開度をＰｅ２ｍｉｎ、第２膨張弁２７ｂの最大開度をＰｅ２ｍａｘ、第２膨張弁２７ｂの開度Ｐｅ２の開度増減値をＤとする。 Further, in the flowchart of FIG. 3, the opening degree of the first expansion valve 27a is Pe1, the opening degree of the second expansion valve 27b is Pe2, the initial opening degree of the first expansion valve 27a at the start of cooling operation is Ped, and the first predetermined. The opening is Pet1, the second predetermined opening is Pet2, the minimum opening of the second expansion valve 27b is Pe2min, the maximum opening of the second expansion valve 27b is Pe2max, and the opening increase / decrease of the opening Pe2 of the second expansion valve 27b. Let the value be D.

ここで、初期開度Ｐｅｄは、冷房運転を開始してから冷媒回路１０の各所における圧力や温度が安定するのにかかる所定時間（例えば、３分間）の間、維持される開度であり、冷房運転開始時の外気温度や室内機３で求められる冷房能力によって決定される。また、第２膨張弁２７ｂを最小開度Ｐｅ２ｍｉｎとするために第２膨張弁２７ｂに加えられるパルス数は一例として５０パルス、第２膨張弁２７ｂを最大開度Ｐｅ２ｍａｘとするために第２膨張弁２７ｂに加えられるパルス数は一例として５００パルスである。さらには、開度増減値Ｄは、一例として５０パルスである。 Here, the initial opening degree Ped is an opening degree maintained for a predetermined time (for example, 3 minutes) required for the pressure and temperature in various parts of the refrigerant circuit 10 to stabilize after the cooling operation is started. It is determined by the outside air temperature at the start of the cooling operation and the cooling capacity required by the indoor unit 3. Further, the number of pulses applied to the second expansion valve 27b to set the second expansion valve 27b to the minimum opening Pe2min is 50 pulses as an example, and the second expansion valve to set the second expansion valve 27b to the maximum opening Pe2max. The number of pulses applied to 27b is, for example, 500 pulses. Further, the opening increase / decrease value D is 50 pulses as an example.

まず、ＣＰＵ２１０は、使用者の運転指示が冷房運転指示であるか否かを判断する（ＳＴ１）。使用者の運転指示が冷房運転指示でなければ（ＳＴ１－Ｎｏ）、つまり、使用者の運転指示が暖房運転であれば、ＣＰＵ２１０は、暖房運転の開始処理である暖房運転開始処理を実行する（ＳＴ２１）。ここで、暖房運転開始処理とは、ＣＰＵ２１０が冷媒回路１０を暖房サイクルとすることであり、空気調和装置１が停止している状態から暖房運転を開始するとき、もしくは、冷房運転から暖房運転に切り替えられる際に行われる処理である。 First, the CPU 210 determines whether or not the user's operation instruction is a cooling operation instruction (ST1). If the user's operation instruction is not a cooling operation instruction (ST1-No), that is, if the user's operation instruction is a heating operation, the CPU 210 executes a heating operation start process, which is a heating operation start process (ST1-No). ST21). Here, the heating operation start process means that the CPU 210 sets the refrigerant circuit 10 as a heating cycle, and when the heating operation is started from the state where the air conditioner 1 is stopped, or from the cooling operation to the heating operation. This is the process performed when switching.

そして、ＣＰＵ２１０は、暖房運転の制御を開始し（ＳＴ２２）、ＳＴ１０に処理を進める。具体的には、ＣＰＵ２１０は、圧縮機２１や室外ファン２４を室内機３で要求された暖房能力に応じた回転数で駆動する。また、ＣＰＵ２１０は、第１膨張弁２７ａの開度を吐出温度センサ７３で検出した吐出温度が予め定められている目標温度となるように調整するとともに、第２膨張弁２７ｂを全開（最大開度）とする。さらには、ＣＰＵ２１０は、通信部２３０を介して室内機３に対し室内ファン３２の駆動制御を行うよう指示する。 Then, the CPU 210 starts controlling the heating operation (ST22) and proceeds to ST10. Specifically, the CPU 210 drives the compressor 21 and the outdoor fan 24 at a rotation speed corresponding to the heating capacity required by the indoor unit 3. Further, the CPU 210 adjusts the opening degree of the first expansion valve 27a so that the discharge temperature detected by the discharge temperature sensor 73 becomes a predetermined target temperature, and fully opens the second expansion valve 27b (maximum opening degree). ). Further, the CPU 210 instructs the indoor unit 3 to drive and control the indoor fan 32 via the communication unit 230.

ＳＴ１において、使用者の運転指示が冷房運転指示であれば（ＳＴ１－Ｙｅｓ）、ＣＰＵ２１０は、冷房運転開始処理を実行する（ＳＴ２）。ここで、冷房運転開始処理とは、ＣＰＵ２１０が冷媒回路１０を冷房サイクルとすることであり、空気調和装置１が停止している状態から冷房運転を開始するとき、もしくは、暖房運転から冷房運転に切り替えられる際に行われる処理である。 In ST1, if the user's operation instruction is a cooling operation instruction (ST1-Yes), the CPU 210 executes the cooling operation start process (ST2). Here, the cooling operation start process means that the CPU 210 sets the refrigerant circuit 10 as a cooling cycle, and when the cooling operation is started from the state where the air conditioner 1 is stopped, or from the heating operation to the cooling operation. This is the process performed when switching.

次に、ＣＰＵ２１０は、タイマー計測を開始し（ＳＴ３）、圧縮機２１と室外ファン２４とを駆動する（ＳＴ４）。具体的には、ＣＰＵ２１０は、冷房運転を行う室内機３からの要求能力に応じた回転数で圧縮機２１や室外ファン２４を起動する。なお、ＣＰＵ２１０は、内部にタイマー計測機能を有している。 Next, the CPU 210 starts timer measurement (ST3) and drives the compressor 21 and the outdoor fan 24 (ST4). Specifically, the CPU 210 activates the compressor 21 and the outdoor fan 24 at a rotation speed corresponding to the required capacity from the indoor unit 3 that performs the cooling operation. The CPU 210 has an internal timer measurement function.

次に、ＣＰＵ２１０は、ＳＴ３でタイマー計測を開始してから所定時間が経過したか否かを判断する（ＳＴ５）。所定時間が経過していなければ（ＳＴ５－Ｎｏ）、ＣＰＵ２１０は、第１膨張弁２７ａの開度Ｐｅ１を初期開度Ｐｅｄとするとともに第２膨張弁２７ｂの開度Ｐｅ２を全閉として（ＳＴ２０）、ＳＴ１０に処理を進める。 Next, the CPU 210 determines whether or not a predetermined time has elapsed since the timer measurement was started in ST3 (ST5). If the predetermined time has not elapsed (ST5-No), the CPU 210 sets the opening Pe1 of the first expansion valve 27a to the initial opening Ped and fully closes the opening Pe2 of the second expansion valve 27b (ST20). , ST10 to proceed.

所定時間が経過していれば（ＳＴ５－Ｙｅｓ）、ＣＰＵ２１０は、吐出温度センサ７３で検出した吐出温度をセンサ入力部２４０を介して取り込む（ＳＴ６）。なお、ＣＰＵ２１０は、吐出温度を定期的（例えば、３０秒毎）に取り込み、取り込んだ吐出温度を記憶部２２０に記憶している。 If the predetermined time has elapsed (ST5-Yes), the CPU 210 captures the discharge temperature detected by the discharge temperature sensor 73 via the sensor input unit 240 (ST6). The CPU 210 takes in the discharge temperature periodically (for example, every 30 seconds), and stores the taken-in discharge temperature in the storage unit 220.

次に、ＣＰＵ２１０は、取り込んだ吐出温度が目標温度となるように、第１膨張弁２７ａの開度Ｐｅ１を調整する（ＳＴ７）。具体的には、ＣＰＵ２１０は、取り込んだ吐出温度が目標温度よりも高い場合は、第１膨張弁２７ａの開度Ｐｅ１を現在の開度より大きくし、取り込んだ吐出温度が目標温度よりも低い場合は、第１膨張弁２７ａの開度Ｐｅ１を現在の開度より小さくする。なお、目標温度は予め記憶部２２０に記憶されており、ＣＰＵ２１０は、記憶部２２０から目標温度を読み出して取り込んだ吐出温度と比較する。 Next, the CPU 210 adjusts the opening degree Pe1 of the first expansion valve 27a so that the taken-in discharge temperature becomes the target temperature (ST7). Specifically, when the taken-in discharge temperature is higher than the target temperature, the CPU 210 increases the opening degree Pe1 of the first expansion valve 27a to be larger than the current opening degree, and the taken-in discharge temperature is lower than the target temperature. Makes the opening degree Pe1 of the first expansion valve 27a smaller than the current opening degree. The target temperature is stored in the storage unit 220 in advance, and the CPU 210 reads the target temperature from the storage unit 220 and compares it with the discharge temperature taken in.

次に、ＣＰＵ２１０は、第１膨張弁２７ａの開度Ｐｅ１が第１所定開度Ｐｅｔ１以上であるか否かを判断する（ＳＴ８）。第１膨張弁２７ａの開度Ｐｅ１が第１所定開度Ｐｅｔ１以上である場合は（ＳＴ８－Ｙｅｓ）、ＣＰＵ２１０は、第２膨張弁２７ｂの開度Ｐｅ２が全閉であるか否かを判断する（ＳＴ１３）。 Next, the CPU 210 determines whether or not the opening degree Pe1 of the first expansion valve 27a is equal to or larger than the first predetermined opening degree Pet1 (ST8). When the opening degree Pe1 of the first expansion valve 27a is equal to or greater than the first predetermined opening degree Pet1 (ST8-Yes), the CPU 210 determines whether or not the opening degree Pe2 of the second expansion valve 27b is fully closed. (ST13).

第２膨張弁２７ｂの開度Ｐｅ２が全閉である場合は（ＳＴ１３－Ｙｅｓ）、ＣＰＵ２１０は、第２膨張弁２７ｂの開度Ｐｅ２を最小開度Ｐｅ２ｍｉｎとして（ＳＴ１６）、ＳＴ１０に処理を進める。第２膨張弁２７ｂの開度Ｐｅ２が全閉でない場合は（ＳＴ１３－Ｎｏ）、ＣＰＵ２１０は、第２膨張弁２７ｂの開度Ｐｅ２が最大開度Ｐｅ２ｍａｘであるか否かを判断する（ＳＴ１４）。 When the opening degree Pe2 of the second expansion valve 27b is fully closed (ST13-Yes), the CPU 210 sets the opening degree Pe2 of the second expansion valve 27b to the minimum opening degree Pe2min (ST16) and proceeds to ST10. When the opening degree Pe2 of the second expansion valve 27b is not fully closed (ST13-No), the CPU 210 determines whether or not the opening degree Pe2 of the second expansion valve 27b has the maximum opening degree Pe2max (ST14).

第２膨張弁２７ｂの開度Ｐｅ２が最大開度Ｐｅ２ｍａｘである場合は（ＳＴ１４－Ｙｅｓ）、ＳＴ１０に処理を進める。第２膨張弁２７ｂの開度Ｐｅ２が最大開度Ｐｅ２ｍａｘでない場合は（ＳＴ１４－Ｎｏ）、ＣＰＵ２１０は、第２膨張弁２７ｂの開度Ｐｅ２を、現在の第２膨張弁２７ｂの開度Ｐｅ２に開度増減値Ｄを加えた開度として（ＳＴ１５）、ＳＴ１０に処理を進める。 When the opening degree Pe2 of the second expansion valve 27b is the maximum opening degree Pe2max (ST14-Yes), the process proceeds to ST10. When the opening degree Pe2 of the second expansion valve 27b is not the maximum opening degree Pe2max (ST14-No), the CPU 210 opens the opening degree Pe2 of the second expansion valve 27b to the current opening degree Pe2 of the second expansion valve 27b. The process proceeds to ST10 as the opening degree to which the degree increase / decrease value D is added (ST15).

ＳＴ８において、第１膨張弁２７ａの開度Ｐｅ１が第１所定開度Ｐｅｔ１以上でない場合は（ＳＴ８－Ｎｏ）、ＣＰＵ２１０は、第１膨張弁２７ａの開度Ｐｅ１が第２所定開度Ｐｅｔ２以下であるか否かを判断する（ＳＴ９）。第１膨張弁２７ａの開度Ｐｅ１が第２所定開度Ｐｅｔ２以下でない場合は（ＳＴ９－Ｎｏ）、ＣＰＵ２１０は、第２膨張弁２７ｂの開度を現在の開度に維持して、ＳＴ１０に処理を進める。 In ST8, when the opening degree Pe1 of the first expansion valve 27a is not equal to or more than the first predetermined opening degree Pet1 (ST8-No), the CPU 210 has the opening degree Pe1 of the first expansion valve 27a not equal to or less than the second predetermined opening degree Pet2. It is determined whether or not there is (ST9). When the opening degree Pe1 of the first expansion valve 27a is not equal to or less than the second predetermined opening degree Pet2 (ST9-No), the CPU 210 maintains the opening degree of the second expansion valve 27b at the current opening degree and processes it in ST10. To proceed.

第１膨張弁２７ａの開度Ｐｅ１が第２所定開度Ｐｅｔ２以下である場合は（ＳＴ９－Ｙｅｓ）、ＣＰＵ２１０は、第２膨張弁２７ｂの開度が最小開度Ｐｅ２ｍｉｎであるか否かを判断する（ＳＴ１７）。第２膨張弁２７ｂの開度が最小開度Ｐｅ２ｍｉｎである場合は（ＳＴ１７－Ｙｅｓ）、ＣＰＵ２１０は、第２膨張弁２７ｂの開度を全閉として（ＳＴ１９）、ＳＴ１０に処理を進める。第２膨張弁２７ｂの開度が最小開度Ｐｅ２ｍｉｎでない場合は（ＳＴ１７－Ｎｏ）、第２膨張弁２７ｂの開度Ｐｅ２を、現在の第２膨張弁２７ｂの開度Ｐｅ２から開度増減値Ｄを減じた開度として（ＳＴ１８）、ＳＴ１０に処理を進める。 When the opening degree Pe1 of the first expansion valve 27a is equal to or less than the second predetermined opening degree Pet2 (ST9-Yes), the CPU 210 determines whether or not the opening degree of the second expansion valve 27b is the minimum opening degree Pe2min. (ST17). When the opening degree of the second expansion valve 27b is the minimum opening degree Pe2min (ST17-Yes), the CPU 210 sets the opening degree of the second expansion valve 27b fully closed (ST19) and proceeds to ST10. If the opening degree of the second expansion valve 27b is not the minimum opening degree Pe2min (ST17-No), the opening degree Pe2 of the second expansion valve 27b is set to the opening degree increase / decrease value D from the current opening degree Pe2 of the second expansion valve 27b. (ST18), and the process proceeds to ST10.

ＳＴ９あるいはＳＴ１８～２０あるいはＳＴ２２のいずれかの処理を終えたＣＰＵ２１０は、使用者による運転モード切替指示があるか否かを判断する（ＳＴ１０）。ここで、運転モード切替指示とは、現在の運転（冷房運転あるいは暖房運転）から別の運転（暖房運転あるいは冷房運転）への切替を指示するものである。運転モード切替指示がある場合は（ＳＴ１０－Ｙｅｓ）、ＣＰＵ２１０は、ＳＴ１に処理を戻す。運転モード切替指示がない場合は（ＳＴ１０－Ｎｏ）、ＣＰＵ２１０は、使用者による運転停止指示があるか否かを判断する（ＳＴ１１）。 The CPU 210 that has completed the processing of ST9, ST18-20, or ST22 determines whether or not there is an operation mode switching instruction by the user (ST10). Here, the operation mode switching instruction is an instruction to switch from the current operation (cooling operation or heating operation) to another operation (heating operation or cooling operation). If there is an operation mode switching instruction (ST10-Yes), the CPU 210 returns the process to ST1. If there is no operation mode switching instruction (ST10-No), the CPU 210 determines whether or not there is an operation stop instruction by the user (ST11).

運転停止指示があれば（ＳＴ１１－Ｙｅｓ）、ＣＰＵ２１０は、運転停止処理を実行するとともにタイマーをリセットして（ＳＴ１２）、処理を終了する。運転停止処理では、ＣＰＵ２１０は、圧縮機２１や室外ファン２４を停止するとともに第１膨張弁２４ａおよび第２膨張弁２４ｂをそれぞれ全閉とする。また、ＣＰＵ２１０は、室内機３に対し通信部２３０を介して運転を停止する旨の運転停止信号を送信する。運転停止信号を受信した室内機３は、室内ファン３２を停止する。 If there is an operation stop instruction (ST11-Yes), the CPU 210 executes the operation stop process and resets the timer (ST12) to end the process. In the operation stop process, the CPU 210 stops the compressor 21 and the outdoor fan 24, and closes the first expansion valve 24a and the second expansion valve 24b, respectively. Further, the CPU 210 transmits an operation stop signal to the effect that the operation is stopped to the indoor unit 3 via the communication unit 230. Upon receiving the operation stop signal, the indoor unit 3 stops the indoor fan 32.

ＳＴ１１において運転停止指示がなければ（ＳＴ１１－Ｎｏ）、ＣＰＵ２１０は、現在の運転が冷房運転であるか否かを判断する（ＳＴ２３）。現在の運転が冷房運転でなければ（ＳＴ２３－Ｎｏ）、つまり、現在の運転が暖房運転であれば、ＣＰＵ２１０は、ＳＴ２２に処理を戻す。現在の運転が冷房運転であれば（ＳＴ２３－Ｙｅｓ）、ＣＰＵ２１０は、ＳＴ４に処理を戻す。 If there is no operation stop instruction in ST11 (ST11-No), the CPU 210 determines whether or not the current operation is a cooling operation (ST23). If the current operation is not a cooling operation (ST23-No), that is, if the current operation is a heating operation, the CPU 210 returns the process to ST22. If the current operation is a cooling operation (ST23-Yes), the CPU 210 returns the process to ST4.

以上説明したように、本実施形態の空気調和機１では、第１膨張弁２７ａの開度が第１所定開度より大きいときは、第２膨張弁２７ｂの開度を現在の開度より大きくして液側配管を流れる冷媒の密度を高くする。一方、第１膨張弁２７ａの開度が第２所定開度より小さいときは、第２膨張弁２７ｂの開度を現在の開度より小さくして液管４を流れる冷媒の密度を小さくする。これにより、液管４を細くして冷媒回路１０に充填する冷媒量を削減しても、冷房運転時に室内熱交換器３１における凝縮能力を確保して要求される冷房能力を発揮させつつ、吐出温度が高い場合はこれを確実に低下させることができる。 As described above, in the air conditioner 1 of the present embodiment, when the opening degree of the first expansion valve 27a is larger than the first predetermined opening degree, the opening degree of the second expansion valve 27b is made larger than the current opening degree. The density of the refrigerant flowing through the liquid side piping is increased. On the other hand, when the opening degree of the first expansion valve 27a is smaller than the second predetermined opening degree, the opening degree of the second expansion valve 27b is made smaller than the current opening degree to reduce the density of the refrigerant flowing through the liquid pipe 4. As a result, even if the liquid pipe 4 is thinned to reduce the amount of refrigerant to be filled in the refrigerant circuit 10, the condensing capacity of the indoor heat exchanger 31 is secured during the cooling operation and the required cooling capacity is exhibited while discharging. If the temperature is high, this can be reliably reduced.

また、本実施形態の空気調和機１では、第２膨張弁２７ｂの開度を現在の開度より大きくするときに、現在の第２膨張弁２７ｂの開度が最大開度Ｐｅ２ｍａｘである場合はこの開度を維持し、現在の第２膨張弁２７ｂの開度が全閉である場合は第２膨張弁２７ｂの開度を最小開度Ｐｅ２ｍｉｎとする。これにより、第２膨張弁２７ｂの開度を現在の開度より大きくするときに、確実に現在の開度より大きくできる。また、第２膨張弁２７ｂの開度を現在の開度より小さくするときに、現在の第２膨張弁２７ｂの開度が最小開度Ｐｅ２ｍｉｎである場合は、第２膨張弁２７ｂの開度を全閉とする。これにより、第２膨張弁２７ｂの開度を現在の開度より小さくするときに、確実に現在の開度より小さくできる。 Further, in the air conditioner 1 of the present embodiment, when the opening degree of the second expansion valve 27b is made larger than the current opening degree, the current opening degree of the second expansion valve 27b is the maximum opening degree Pe2max. When this opening degree is maintained and the current opening degree of the second expansion valve 27b is fully closed, the opening degree of the second expansion valve 27b is set to the minimum opening degree Pe2min. As a result, when the opening degree of the second expansion valve 27b is made larger than the current opening degree, it can be surely made larger than the current opening degree. Further, when the opening degree of the second expansion valve 27b is made smaller than the current opening degree, if the current opening degree of the second expansion valve 27b is the minimum opening degree Pe2min, the opening degree of the second expansion valve 27b is increased. Fully closed. As a result, when the opening degree of the second expansion valve 27b is made smaller than the current opening degree, it can be surely made smaller than the current opening degree.

１空気調和機
２室外機
３室内機
１０冷媒回路
２１圧縮機
２２四方弁
２３室外熱交換器
２７ａ第１膨張弁
２７ｂ第２膨張弁
２８気液分離器
２９開閉弁
３０ａ第１逆止弁
３０ｂ第２逆止弁
６７第一液分管
６８第二液分管
６９バイパス管
７３吐出温度センサ
Ｐｅ１第１膨張弁開度
Ｐｅｄ初期開度
Ｐｅｔ１第１所定開度
Ｐｅｔ２第２所定開度
Ｐｅ２第２膨張弁開度
Ｐｅ２ｍｉｎ最小開度
Ｐｅ２ｍａｘ最大開度
Ｄ開度増減値 1 Air conditioner 2 Outdoor unit 3 Indoor unit 10 Refrigerant circuit 21 Compressor 22 Four-way valve 23 Outdoor heat exchanger 27a 1st expansion valve 27b 2nd expansion valve 28 Air-liquid separator 29 On-off valve 30a 1st check valve 30b 1st 2 Check valve 67 1st liquid branch pipe 68 2nd liquid branch pipe 69 Bypass pipe 73 Discharge temperature sensor Pe1 1st expansion valve opening Ped Initial opening Pet1 1st predetermined opening Pet2 2nd predetermined opening Pe2 2nd expansion valve open Degree Pe2min Minimum opening Pe2max Maximum opening D Opening increase / decrease value

Claims

A refrigerant circuit in which the refrigerant circulates in the order of the compressor, outdoor heat exchanger, first expansion valve, gas-liquid separator, and indoor heat exchanger during cooling operation.
A bypass pipe provided with a second expansion valve to guide the refrigerant from the gas-liquid separator to the compressor,
A control means for adjusting the opening degree of the first expansion valve and the opening degree of the second expansion valve, and
It is an air conditioner with
When the control means is performing cooling operation,
The opening degree of the first expansion valve is adjusted so that the discharge temperature, which is the temperature of the refrigerant discharged from the compressor, becomes a predetermined target temperature.
When the opening degree of the first expansion valve is larger than the predetermined first predetermined opening degree, the opening degree of the second expansion valve is made larger than the current opening degree, and the opening degree of the first expansion valve is increased. If it is smaller than the first predetermined opening and smaller than the predetermined second predetermined opening, it is made smaller than the current opening.
An air conditioner characterized by that.

The control means is
When the opening degree of the second expansion valve is made larger than the current opening degree, this state is maintained when the opening degree of the current second expansion valve is the maximum opening degree, and the current opening degree of the second expansion valve is maintained. If the opening is fully closed, set it to the minimum opening.
The air conditioner according to claim 1, wherein the air conditioner is characterized by the above.

The control means is
When the opening of the second expansion valve is made smaller than the current opening, if the current opening of the second expansion valve is the minimum opening, the opening of the second expansion valve is fully closed. ,
The air conditioner according to claim 1, wherein the air conditioner is characterized by the above.