JP3680225B2

JP3680225B2 - Refrigerant circuit

Info

Publication number: JP3680225B2
Application number: JP08643596A
Authority: JP
Inventors: 敏幸夏目; 昌弥繁永; 高宏岡本; 幸正矢野
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 1996-04-09
Filing date: 1996-04-09
Publication date: 2005-08-10
Anticipated expiration: 2016-04-09
Also published as: JPH09280680A

Description

【０００１】
【発明の属する技術分野】
この発明は、室内外熱交換器の対向流化と膨張弁流下方向の規定とを行う冷媒回路に関する。
【０００２】
【従来の技術】
一般に、非共沸冷媒を使用する空気調和機や冷凍機の能力および成績係数を向上させる為に、室内外熱交換器の対向流化や過冷却熱交換器の使用が行われる。その際に、冷房時および暖房時の両方において熱交換器の対向流化や過冷却熱交換器の使用を可能にする為に、４つの逆止弁を用いた逆止弁ブリッジを用いて、冷房時・暖房時の何れの場合でも室内外熱交換器や過冷却熱交換器における冷媒流の方向が同一になるようにしている。
【０００３】
また、ハイドロクロロフルオロカーボン(以下、ＨＣＦＣと略称する)系の冷媒Ｒ２２の代替冷媒としてハイドロフルオロカーボン(ＨＦＣと略称する)系の冷媒を用いると共に、冷凍機油として合成油(エステル油,エーテル油,アルキルベンゼン油等)を用いた空気調和機においては、冷媒系内の残留不純物(切削油,加工油,金属粉等)から生成されるスラッジの付着によって、膨張弁が詰まったり動作不良を起こしたりする。その際に、流下方向によってスラッジの付着量に差異がある構造を有している膨張弁を使用している場合には、膨張弁流下方向をスラッジが付着しにくい方向に規定することによって、上述の問題に対処できるのである。
【０００４】
従来、室内外熱交換器の対向流化と膨張弁流下方向の規定とを行う場合には、図４に示すような逆止弁ブリッジ冷媒回路を用いている。
この逆止弁ブリッジ冷媒回路は、４個の逆止弁１〜逆止弁４を環状に連結してなる第１逆止弁ブリッジ５と、４個の逆止弁６〜逆止弁９を環状に連結してなる第２逆止弁ブリッジ１０と、４個の逆止弁１１〜逆止弁１４を環状に連結してなる第３逆止弁ブリッジ１５とを用い、第１逆止弁ブリッジ５の隣接する２つの逆止弁３,４の間と第２逆止弁ブリッジ１０の隣接する２つの逆止弁６,７の間とを連結し、第２逆止弁ブリッジ１０の隣接する２つの逆止弁８,９の間と第３逆止弁ブリッジ１５の隣接する２つの逆止弁１１,１２の間とを連結している。
さらに、上記第１逆止弁ブリッジ５の隣接する２つの逆止弁１,２の間、四路切換弁１６、圧縮機１７、アキュムレータ１８、四路切換弁１６、第３逆止弁ブリッジ１５の隣接する２つの逆止弁１３,１４の間を順次連結している。
【０００５】
そして、上記第１逆止弁ブリッジ５の隣接する逆止弁１,４の間と逆止弁２,３の間とを室外熱交換器１９を介して連結し、第２逆止弁ブリッジ１０の隣接する逆止弁６,９の間と逆止弁７,８の間とを電動膨張弁２０を介して連結し、第３逆止弁ブリッジ１５の隣接する逆止弁１１,１４の間と逆止弁１２,１３の間とを室内熱交換器２１を介して連結している。
【０００６】
上記構成において、冷房時には、四路切換弁１６を実線のように切り換えることによって冷媒は実線の矢印のごとく流れる。一方、暖房時には、四路切換弁１６を破線のように切り換えることによって冷媒は破線の矢印のごとく流れる。その場合に、室外熱交換器１９,電動膨張弁２０および室内熱交換器２１を流れる冷媒の方向は、冷房時および暖房時に拘わらず同じ方向となる。
したがって、室内外熱交換器の対向流化と膨張弁流下方向の規定とが行われるのである。
【０００７】
また、通常、冷房運転時においては、室外熱交換器を出た冷媒は過冷却状態にあり、室内熱交換器を出た冷媒は過熱状態にある。これに対して、暖房運転時においては、室内熱交換器を出た冷媒は過冷却状態にあり、室外熱交換器を出た冷媒は過熱状態にある。つまり、冷房運転時あるいは暖房運転時に拘わらず凝縮器を出た冷媒が過冷却状態となる一方、蒸発器を出た冷媒が過熱状態となる。そこで、この過冷却状態にある冷媒と過熱状態にある冷媒との(より端的に言えば、室内外熱交換器を出た冷媒同士の)熱交換(過冷却熱交換)を行うことによって空気調和機の成績係数を上げることができる。その際に、上記過冷却熱交換は対向流によって行う方が熱交換効率がよい。
【０００８】
図５は、図４に示す逆止弁ブリッジ冷媒回路に過冷却熱交換器２５を設けた逆止弁ブリッジ冷媒回路である。ここで、過冷却熱交換器２５は二重管熱交換器で構成され、その外管は、逆止弁ブリッジ冷媒回路の第２逆止弁ブリッジ１０において、隣接する逆止弁６,９の間と逆止弁７,８の間とを連結する冷媒管における電動膨張弁２０の上流側に介接されている。一方、内管は、四路切換弁１６とアキュムレータ１８とを連結する冷媒管に介接されている。
ここで、上述したように、上記電動膨張弁２０へ向かう冷媒の方向は冷・暖房時に拘わらず同じ方向であり、圧縮機１７への戻り冷媒の方向も冷暖房時に拘わらず同じ方向であって電動膨張弁２０へ向かう冷媒の方向とは逆方向である。したがって、過冷却熱交換器２５によって行われる過冷却熱交換は冷・暖房時に拘わらず対向流によって行われるのである。
【０００９】
【発明が解決しようとする課題】
しかしながら、上記従来の逆止弁ブリッジ冷媒回路においては、流下方向を規定しようとする機器の数に相当する逆止弁ブリッジを必要とする。したがって、上述のように、室内外熱交換器の対向流化と膨張弁流下方向の規定とを行う場合には、流下方向を規定しようとする機器の数が３であるから４個の逆止弁からなる逆止弁ブリッジを３組必要とし、使用される逆止弁が１２個と多くなる。したがって、本来の空気調和機能以外に必要な補助スペースの拡大やコストの増大を招くという問題がある。特に、室内に設置される室内ユニット２２は可能な限り小型にすることが望ましく、上述のような逆止弁ブリッジを組み込むことは避けたい。
また、多くの逆止弁を使用するということは故障の可能性が高くなり、それだけ製品信頼性が低下するという問題もある。
【００１０】
そこで、この発明の目的は、４個の逆止弁と２個の電動弁を用いて室内外熱交換器の対向流化と膨張弁流下方向の規定とを行うことができる冷媒回路を提供することにある。
【００１１】
【課題を解決するための手段】
上記目的を達成するため、請求項１に係る発明の冷媒回路は、第１逆止弁,室外熱交換器および第２逆止弁を,冷媒の流れる方向が一方向になるように冷媒管を介して順次環状に接続し、第３逆止弁,第４逆止弁および室内熱交換器を,冷媒の流れる方向が一方向になるように冷媒管を介して順次環状に接続し、上記第１逆止弁および室外熱交換器の間と上記第３逆止弁および室内熱交換器の間とを,第１電動膨張弁が介設された冷媒管で連結し、上記第２逆止弁および室外熱交換器の間と上記第４逆止弁および室内熱交換器の間とを,第２電動膨張弁が介設された冷媒管で連結し、上記第１逆止弁および第２逆止弁の間と圧縮機の吐出口とを,四路切換弁を介して冷媒管で連結し、上記第３逆止弁および第４逆止弁の間と上記圧縮機の吸入口とを,上記四路切換弁を介して冷媒管で連結したことを特徴としている。
【００１２】
上記構成において、冷房時には、上記第１電動膨張弁が全閉されると共に、四路切換弁が切り換えられて圧縮機からの高温高圧冷媒が第１逆止弁と第２逆止弁との間に供給される。そうすると、上記冷媒は、上記第１電動膨張弁によって遮られ、且つ、第２逆止弁および第４逆止弁の下流側が上流側より高圧であるために第２,第４逆止弁を通過できず、第１逆止弁→室外熱交換器→第２電動膨張弁→室内熱交換器→第３逆止弁→四路切換弁→圧縮機となる。
これに対して、暖房時には、上記第２電動膨張弁が全閉されると共に、四路切換弁が切り換えられて圧縮機からの冷媒が上記第３逆止弁と第４逆止弁との間に供給される。そうすると、上記冷媒は、上記第２電動膨張弁によって遮られ、且つ、第３逆止弁および第１逆止弁の下流側が上流側より高圧であるために第３,第１逆止弁を通過できず、第４逆止弁→室内熱交換器→第１電動膨張弁→室外熱交換器→第２逆止弁→四路切換弁→圧縮機となる。
【００１３】
その結果、冷房時および暖房時の何れの場合においても、上記室外熱交換器,室内熱交換器および第１,第２電動膨張弁を通過する冷媒の方向は同一方向となる。こうして、４個の逆止弁と２個の電動膨張弁とを用いた冷媒回路によって室内外熱交換器の対向流化と膨張弁流下方向の規定とが行われる。
【００１４】
また、請求項２に係る発明は、請求項１に係る発明の冷媒回路において、上記第１電動膨張弁および第２電動膨張弁は、冷媒を一方向に流した場合のスラッジの付着量が他方向に流した場合の付着量に比して少ない構造を有していることを特徴としている。
【００１５】
上記構成によれば、冷房時および暖房時に拘わらず第１,第２電動膨張弁を通過する冷媒の方向は同一方向であるから、上記第１,第２電動膨張弁の流下方向をスラッジの付着量が少ない方向とすることによって、両電動膨張弁の信頼性が高められる。
【００１６】
また、請求項３に係る発明は、請求項１に係る発明の冷媒回路において、上記室外熱交換器を出た冷媒と上記室内熱交換器を出た冷媒との過冷却熱交換をおこなう過冷却熱交換器を備えたことを特徴としている。
【００１７】
上記構成によれば、過冷却熱交換器によって、凝縮器を出た過冷却状態の冷媒と蒸発器を出た過熱状態の冷媒との間の過冷却熱交換が行われる。その際に、上記凝縮器および蒸発器を出た冷媒の流れる方向は冷房時および暖房時に拘わらず同一方向であるから、上記過冷却熱交換を対向流で行うことが可能となる。こうして、請求項１に係る発明の冷媒回路の更なる成績係数の向上が図られる。
【００１８】
【発明の実施の形態】
以下、この発明を図示の実施の形態により詳細に説明する。
＜第１実施の形態＞
図１は本実施の形態における冷媒回路を示す図である。本冷媒回路は次のような構成を有している。
すなわち、逆止弁３１,室外熱交換器３２および逆止弁３３を、冷媒の流れる方向が一方向になるように、冷媒管を介して順次環状に接続する。また、逆止弁３４,逆止弁３５および室内熱交換器３６を、冷媒の流れる方向が一方向になるように、冷媒管を介して順次環状に接続する。そして、逆止弁３１および室外熱交換器３２の間と逆止弁３４および室内熱交換器３６の間とを、全閉可能な第１電動膨張弁３７が介設された冷媒管で接続する。同様に、逆止弁３３および室外熱交換器３２の間と逆止弁３５および室内熱交換器３６の間とを、全閉可能な第２電動膨張弁３８が介設された冷媒管で接続する。
さらに、上記逆止弁３１および逆止弁３３の間と圧縮機３９の吐出口とを四路切換弁４０を介して冷媒管で接続する。一方、逆止弁３４および逆止弁３５の間と圧縮機３９の吸入口とを四路切換弁４０およびアキュムレータ４１を介して冷媒管で接続する。
【００１９】
ここで、上記第１電動膨張弁３７および第２電動膨張弁３８は、図２に示すようなニードル弁体を用いた構造を有しており、凝縮器からの高圧液冷媒を破線の矢印Ｂのようにニードル弁体４５の根元側から供給した場合には、高圧液冷媒がコイル４６やロータ４７やシャフト４８やケーシング４９の間に入り込むような構造になっている。したがって、上述のごとく、ＨＦＣ系の冷媒を用い、冷凍機油として合成油を用いた場合には、加工油,組立油,防錆油または洗浄油等の不純物が溶解されたり金属粉が分散している高圧液冷媒/合成油が上記隙間に入り込む。そして、停止状態や均圧状態となった場合には減圧されて冷媒および合成油が蒸発し、冷媒/合成油中に析出した上記不純物や金属粉がスラッジを形成してコイル４６やロータ４７やシャフト４８やケーシング４９の間やニードル弁体４５の表面に堆積するのである。
こうして、上記ニードル弁体４５と弁座５０との隙間が詰まったり、シャフト４８が動作不良を起こしたりするようになる。
【００２０】
これに対して、凝縮器からの高圧液冷媒を実線の矢印Ａのようにニードル弁体４５の先端側から供給した場合には、流体流れの再付着現象によってスラッジがニードル弁体４５の上部に付着する。ところが、ニードル弁体４５と弁座５０との隙間を流れる冷媒の流速が速く、強い剪断力が作用して、付着したスラッジが成長して堆積することはない。また、減圧されて上記不純物や金属粉が析出している低圧の２相冷媒/合成油は、コイル４６やロータ４７やシャフト４８やケーシング４９の間に入り込むことはないのである。
つまり、上記第１,第２電動膨張弁３７,３８は、流下方向を矢印Ａの如く規定することによってスラッジが付着しにくい構造になっているのである。
【００２１】
また、上記４個の逆止弁３１,３３,３４,３５と２個の電動膨張弁３７,３８とは、室外熱交換器３２,圧縮機３９,四路切換弁４０およびアキュムレータ４１と共に、室外ユニット４２を形成している。これに対して、室内ユニット４３は室内熱交換器３６のみで形成されている。したがって、本実施の形態における室内ユニット４３は、本来の空気調和機能以外の補助スペースが最小になっている。
【００２２】
上記構成の冷媒回路は次のように動作する。
（１）冷房運転
冷房運転時には、上記四路切換弁４０を実線のように切り換えると共に、第１電動膨張弁３７を全閉にする一方、第２電動膨張弁３８の開度を制御する。
そうすると、実線の矢印(イ)で示すように四路切換弁４０を通過した冷媒は、逆止弁３３に遮られて逆止弁３１を通過し、全閉された第１電動膨張弁３７によって遮られて室外熱交換器３２側に流れる。そして、室外熱交換器３２によって凝縮された冷媒は、逆止弁３３の下流側が上流側より高圧であるために逆止弁３３を通過できずに第２電動膨張弁３８側に流れて減圧される。
【００２３】
こうして、減圧された冷媒は、逆止弁３５によって遮られて室内熱交換器３６側に流れる。そして、室内熱交換器３６で蒸発されて気体となった冷媒は、第１電動膨張弁３７によって遮られて逆止弁３４側に流れ、逆止弁３５の下流側が上流側より高圧であるために逆止弁３５を通過できずに四路切換弁４０側に流れるのである。こうして、四路切換弁４０を通過した冷媒は、アキュムレータ４１を介して圧縮機３９の吸入口に戻る。
このように、冷房運転時においては、冷媒は実線の矢印で示す順路で流れるのである。
【００２４】
（２）暖房運転
暖房運転時には、上記四路切換弁４０を破線のように切り換えると共に、第２電動膨張弁３８を全閉にする一方、第１電動膨張弁３７の開度を制御する。
そうすると、破線の矢印(ロ)で示すように四路切換弁４０を通過した冷媒は、逆止弁３４に遮られて逆止弁３５を通過し、全閉された第２電動膨張弁３８によって遮られて室内熱交換器３６側に流れる。そして、室内熱交換器３６によって凝縮された冷媒は、逆止弁３４の下流側が上流側より高圧であるために逆止弁３４を通過できずに第１電動膨張弁３７側に流れて減圧される。
【００２５】
こうして、減圧された冷媒は、逆止弁３１によって遮られて室外熱交換器３２側に流れる。そして、室外熱交換器３２で蒸発されて気体となった冷媒は、第２電動膨張弁３８によって遮られて逆止弁３３側に流れ、逆止弁３１の下流側が上流側より高圧であるために逆止弁３１を通過できずに四路切換弁４０側に流れるのである。こうして、四路切換弁４０を通過した冷媒は、アキュムレータ４１を介して圧縮機３９の吸入口に戻る。
このように、暖房運転時においては、冷媒は破線の矢印で示す順路で流れるのである。
【００２６】
その結果、図１から分かるように、冷房運転時および暖房運転時の何れ場合にも、室外熱交換器３２および室内熱交換器３６を通過する冷媒の流れる方向は同一である。したがって、室内外熱交換器３２,３６における冷媒流と空気流との方向関係を冷房時および暖房時に拘わらず向流とすることができ(対向流化)、熱交換損失を減少できる。また、各電動膨張弁３７,３８を流れる冷媒の方向は一定である。したがって、第１電動膨張弁３７及び第２電動膨張弁３８の流下方向を図２における矢印Ａになるように設定することによって、スラッジが付着しにくい方向に冷媒を流すことができ、電動膨張弁の信頼性を向上できるのである。
【００２７】
このように、本実施の形態における冷媒回路によれば、図４に示すような１２個の逆止弁を用いた従来の逆止弁ブリッジ冷媒回路の場合より少ない４個の逆止弁と２つの電動膨張弁とで、上記従来の逆止弁ブリッジ冷媒回路と同じように室内外熱交換器の対向流化と膨張弁流下方向の規定とを行うことができる。したがって、本実施の形態によれば、室内外熱交換器の対向流化と膨張弁流下方向の規定とを行うに際して、冷媒回路の組み込みスペースの拡大やコストの増大や製品信頼性の低下を極力押さえることができるのである。
【００２８】
さらに、上記２つの電動膨張弁３７,３８として、流下方向を規制することによってスラッジの付着を低減できる構造の電動膨張弁を使用し、且つ、冷房時または暖房時の何れか一方の際に電動膨張弁３７,３８の何れか一方を使用する(つまり、動作不良を起こす機会を１/２にする)ことによって、電動膨張弁３７,３８の詰まりによる信頼性の低下を大幅に低下できる。
さらに、上記室内熱交換器３６以外の機器を室外ユニット４２側に収めることができ、室内ユニット４３をコンパクトにできる。
【００２９】
＜第２実施の形態＞
図３は本実施の形態における冷媒回路を示す図である。本冷媒回路は、図１に示す冷媒回路に過冷却熱交換器６２を設けた構造を有している。
すなわち、逆止弁５１,室外熱交換器５２,逆止弁５３,逆止弁５４,逆止弁５５,室内熱交換器５６,第１電動膨張弁５７,第２電動膨張弁５８,圧縮機５９,四路切換弁６０およびアキュムレータ６１は、図１に示す第１実施の形態における逆止弁３１,室外熱交換器３２,逆止弁３３,逆止弁３４,逆止弁３５,室内熱交換器３６,第１電動膨張弁３７,第２電動膨張弁３８,圧縮機３９,四路切換弁４０およびアキュムレータ４１と同様に連結されて同様に動作する。
【００３０】
本実施の形態においては、上記室外熱交換器５２と逆止弁５３とを接続する冷媒管における第２電動膨張弁５８への分岐点ａよりも上流側に、過冷却熱交換器６２の内管を介接している。また、室内熱交換器５６と逆止弁５４とを接続する冷媒管における第１電動膨張弁５７への分岐点ｂよりも上流側に、過冷却熱交換器６２の外管を介接している。こうして、過冷却熱交換器６２によって、過熱状態の冷媒と過冷却状態の冷媒と間の熱交換(過冷却熱交換)を行うのである。
【００３１】
ここで、上述したように、冷媒は、冷・暖房時に拘わらず、上記室外熱交換器５２から分岐点ａに向かって流れる一方、室内熱交換器５６から分岐点ｂに向かって流れ、過冷却熱交換器６２内における両冷媒の通過方向は逆となる。したがって、過冷却熱交換器６２によって行われる過冷却熱交換は、冷・暖房時に拘わらず対向流によって行われるのである。
【００３２】
このように、本実施の形態における冷媒回路においては、室外熱交換器５２と逆止弁５３とを連結する冷媒管における分岐点ａよりも上流側と、室内熱交換器５６と逆止弁５４とを連結する冷媒管における分岐点ｂよりも上流側とに、過冷却熱交換器６２を介接している。そして、室外熱交換器５２および室内熱交換器５６から出て過冷却熱交換器６２を通過する冷媒の方向が常に同一である。したがって、冷房時・暖房時に拘わらず対向流によって過冷却熱交換を行うことができる。
すなわち、本実施の形態によれば、第１実施の形態による効果に加えて、過冷却熱交換による更なる成績係数の向上を図ることができる。
【００３３】
尚、この発明における過冷却熱交換器は、二重管熱交換器に限定されるものではない。
【００３４】
【発明の効果】
以上より明らかなように、請求項１に係る発明の冷媒回路は、４個の逆止弁と２個の電動膨張弁を用いて、冷房時には上記第１電動膨張弁を全閉する一方、暖房時には上記第２電動膨張弁を全閉することによって、冷房時および暖房時の何れの場合においても、上記室外熱交換器,室内熱交換器および第１,第２電動膨張弁を通過する冷媒の方向が同一方向になるようにしたので、４個の逆止弁と２個の電動膨張弁とを用いた冷媒回路によって室内外熱交換器の対向流化と膨張弁流下方向の規定とを行うことができる。
【００３５】
すなわち、この発明によれば、逆止弁４個を用いた逆止弁ブリッジを３組(つまり、１２個の逆止弁を)必要とする冷媒回路に比較して、収納スペースの縮小やコストの低下や製品信頼性の向上を図ることができるのである。
【００３６】
また、請求項２に係る発明の冷媒回路は、上記第１電動膨張弁および第２電動膨張弁として冷媒を一方向に流した場合のスラッジの付着量が他方向に流した場合より少ない構造の電動膨張弁を使用し、且つ、各電動膨張弁の流下方向を規定したので、上記第１,第２電動膨張弁の流下方向をスラッジの付着量が少ない上記一方向とすることによって、冷房時および暖房時に拘わらず第１,第２電動膨張弁の詰まりや動作不良を少なくできる。
したがって、両電動膨張弁の信頼性が高められる。
【００３７】
また、請求項３に係る発明の冷媒回路は、過冷却熱交換器によって、冷房時および暖房時に拘わらず同一方向に上記室外熱交換器および室内熱交換器を通過した冷媒の間で過冷却熱交換をおこなうので、上記過冷却熱交換器を通過する両冷媒の流れる方向を逆にすることによって、凝縮器からの過冷却状態の冷媒と蒸発器からの過熱状態の冷媒との過冷却熱交換を冷房時および暖房時に拘わらず対向流によって行うことができる。
したがって、この発明によれば、請求項１に係る発明の冷媒回路の成績係数を更に向上することができる。
【図面の簡単な説明】
【図１】この発明の冷媒回路における一実施の形態を示す図である。
【図２】図１における電動膨張弁の具体的構造を示す図である。
【図３】図１とは異なる実施の形態を示す図である。
【図４】室内外熱交換器の対向流化と膨張弁流下方向の規定とを行う従来の逆止弁ブリッジ冷媒回路を示す図である。
【図５】室内外熱交換器の対向流化と膨張弁流下方向の規定と過冷却熱交換とを行う従来の逆止弁ブリッジ冷媒回路を示す図である。
【符号の説明】
３１,３３,３４,３５,５１,５３,５４,５５…逆止弁、
３２,５２…室外熱交換器、３６,５６…室内熱交換器、
３７,５７…第１電動膨張弁、３８,５８…第２電動膨張弁、
３９,５９…圧縮機、４０,６０…四路切換弁、
４２…室外ユニット、４３,６３…室内ユニット、
６２…過冷却熱交換器。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigerant circuit that performs counterflow of an indoor / outdoor heat exchanger and regulation of an expansion valve flow direction.
[0002]
[Prior art]
In general, in order to improve the performance and coefficient of performance of air conditioners and refrigerators that use non-azeotropic refrigerants, counter flow of indoor and outdoor heat exchangers and use of supercooled heat exchangers are performed. At that time, in order to enable the use of a counter flow of the heat exchanger and the use of the supercooling heat exchanger in both cooling and heating, using a check valve bridge using four check valves, In either case of cooling or heating, the direction of the refrigerant flow in the indoor / outdoor heat exchanger or the supercooling heat exchanger is made the same.
[0003]
Further, a hydrofluorocarbon (abbreviated as HFC) refrigerant is used as an alternative refrigerant for the hydrochlorofluorocarbon (hereinafter abbreviated as HCFC) refrigerant R22, and a synthetic oil (ester oil, ether oil, alkylbenzene oil) is used as a refrigerating machine oil. Etc.), the expansion valve is clogged or malfunctions due to sludge generated from residual impurities (cutting oil, processing oil, metal powder, etc.) in the refrigerant system. At that time, when an expansion valve having a structure in which the amount of sludge attached differs depending on the flow direction, the expansion valve flow direction is defined as a direction in which sludge does not easily adhere to the above. It can cope with this problem.
[0004]
Conventionally, a check valve bridge refrigerant circuit as shown in FIG. 4 is used when the counter flow of the indoor / outdoor heat exchanger and the regulation of the downward flow direction of the expansion valve are performed.
This check valve bridge refrigerant circuit includes a first check valve bridge 5 formed by annularly connecting four check valves 1 to 4 and four check valves 6 to 9. A first check valve bridge 10 is formed by using a second check valve bridge 10 that is annularly connected and a third check valve bridge 15 that is an annular connection of four check valves 11 to 14. The connection between the two adjacent check valves 3 and 4 of the bridge 5 and the two adjacent check valves 6 and 7 of the second check valve bridge 10 is made adjacent to the second check valve bridge 10. The two check valves 8 and 9 connected to each other and the two adjacent check valves 11 and 12 of the third check valve bridge 15 are connected to each other.
Further, between the two adjacent check valves 1 and 2 of the first check valve bridge 5, a four-way switching valve 16, a compressor 17, an accumulator 18, a four-way switching valve 16, and a third check valve bridge 15. The two adjacent check valves 13 and 14 are sequentially connected.
[0005]
Then, the adjacent check valves 1 and 4 and the check valves 2 and 3 of the first check valve bridge 5 are connected via an outdoor heat exchanger 19, and the second check valve bridge 10 is connected. Between the adjacent check valves 6 and 9 and the check valves 7 and 8 via the electric expansion valve 20, and between the adjacent check valves 11 and 14 of the third check valve bridge 15. And the check valves 12 and 13 are connected via an indoor heat exchanger 21.
[0006]
In the above configuration, during cooling, the refrigerant flows as indicated by the solid line arrow by switching the four-way switching valve 16 as shown by the solid line. On the other hand, at the time of heating, the refrigerant flows as indicated by broken arrows by switching the four-way switching valve 16 as shown by broken lines. In this case, the direction of the refrigerant flowing through the outdoor heat exchanger 19, the electric expansion valve 20, and the indoor heat exchanger 21 is the same regardless of whether it is cooling or heating.
Therefore, the counter flow of the indoor / outdoor heat exchanger and the regulation of the downward flow direction of the expansion valve are performed.
[0007]
In general, during cooling operation, the refrigerant that has exited the outdoor heat exchanger is in a supercooled state, and the refrigerant that has exited the indoor heat exchanger is in an overheated state. In contrast, during the heating operation, the refrigerant that has exited the indoor heat exchanger is in a supercooled state, and the refrigerant that has exited the outdoor heat exchanger is in an overheated state. That is, regardless of the cooling operation or the heating operation, the refrigerant exiting the condenser is in a supercooled state, while the refrigerant exiting the evaporator is in an overheated state. Therefore, air conditioning is performed by performing heat exchange (supercooling heat exchange) between the refrigerant in the supercooled state and the refrigerant in the superheated state (more simply, the refrigerant that has exited the indoor / outdoor heat exchanger). The coefficient of performance of the machine can be increased. At that time, the heat exchange efficiency is better when the supercooling heat exchange is performed by a counter flow.
[0008]
FIG. 5 is a check valve bridge refrigerant circuit in which a supercooling heat exchanger 25 is provided in the check valve bridge refrigerant circuit shown in FIG. Here, the supercooling heat exchanger 25 is composed of a double-tube heat exchanger, and the outer pipe of the second check valve bridge 10 of the check valve bridge refrigerant circuit is connected to the adjacent check valves 6 and 9. Is connected to the upstream side of the electric expansion valve 20 in the refrigerant pipe connecting between the check valve 7 and the check valve 7, 8. On the other hand, the inner pipe is connected to a refrigerant pipe that connects the four-way switching valve 16 and the accumulator 18.
Here, as described above, the direction of the refrigerant toward the electric expansion valve 20 is the same regardless of whether it is cooling or heating, and the direction of the refrigerant returning to the compressor 17 is the same regardless of whether it is cooling or heating. The direction of the refrigerant toward the expansion valve 20 is the opposite direction. Therefore, the supercooling heat exchange performed by the supercooling heat exchanger 25 is performed by the counter flow regardless of the time of cooling / heating.
[0009]
[Problems to be solved by the invention]
However, the conventional check valve bridge refrigerant circuit requires a check valve bridge corresponding to the number of devices for which the flow direction is to be defined. Therefore, as described above, when the counter flow of the indoor / outdoor heat exchanger and the regulation of the expansion valve flow down direction are performed, since the number of devices for defining the flow down direction is 3, 4 check Three sets of check valve bridges consisting of valves are required, and the number of check valves used increases to twelve. Therefore, there is a problem in that the auxiliary space required and the cost are increased in addition to the original air conditioning function. In particular, it is desirable that the indoor unit 22 installed in the room be as small as possible, and it is desirable to avoid incorporating a check valve bridge as described above.
In addition, the use of many check valves increases the possibility of failure, and there is a problem that the product reliability is lowered accordingly.
[0010]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a refrigerant circuit that can perform counter flow of an indoor / outdoor heat exchanger and regulation of the downward flow direction of an expansion valve using four check valves and two motor operated valves. There is.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a refrigerant circuit according to a first aspect of the present invention includes a refrigerant pipe including a first check valve, an outdoor heat exchanger, and a second check valve so that a refrigerant flows in one direction. The third check valve, the fourth check valve, and the indoor heat exchanger are sequentially connected in an annular manner through the refrigerant pipe so that the refrigerant flows in one direction. The first check valve and the outdoor heat exchanger and the third check valve and the indoor heat exchanger are connected by a refrigerant pipe having a first electric expansion valve interposed therebetween, and the second check valve And the outdoor heat exchanger and the fourth check valve and the indoor heat exchanger are connected by a refrigerant pipe having a second electric expansion valve interposed therebetween, and the first check valve and the second check valve are connected to each other. Between the check valves and the discharge port of the compressor are connected by a refrigerant pipe via a four-way switching valve, and between the third check valve and the fourth check valve and the suction port of the compressor, Up It is characterized in that connected in the refrigerant pipe through the four-way switching valve.
[0012]
In the above configuration, at the time of cooling, the first electric expansion valve is fully closed and the four-way switching valve is switched so that the high-temperature and high-pressure refrigerant from the compressor is between the first check valve and the second check valve. To be supplied. Then, the refrigerant is blocked by the first electric expansion valve and passes through the second and fourth check valves because the downstream side of the second check valve and the fourth check valve is higher in pressure than the upstream side. The first check valve → the outdoor heat exchanger → the second electric expansion valve → the indoor heat exchanger → the third check valve → the four-way switching valve → the compressor.
On the other hand, at the time of heating, the second electric expansion valve is fully closed and the four-way switching valve is switched so that the refrigerant from the compressor is between the third check valve and the fourth check valve. To be supplied. Then, the refrigerant is blocked by the second electric expansion valve, and passes through the third and first check valves because the downstream side of the third check valve and the first check valve is higher in pressure than the upstream side. The fourth check valve → the indoor heat exchanger → the first electric expansion valve → the outdoor heat exchanger → the second check valve → the four-way switching valve → the compressor.
[0013]
As a result, the direction of the refrigerant passing through the outdoor heat exchanger, the indoor heat exchanger, and the first and second electric expansion valves is the same in both cases of cooling and heating. In this manner, the refrigerant circuit using the four check valves and the two electric expansion valves makes the indoor / outdoor heat exchanger counterflow and regulates the expansion valve flow direction.
[0014]
The invention according to claim 2 is the refrigerant circuit of the invention according to claim 1, wherein the first electric expansion valve and the second electric expansion valve have different sludge adhesion amounts when the refrigerant flows in one direction. It is characterized by having a structure that is smaller than the amount of adhesion when flowing in the direction.
[0015]
According to the above configuration, the direction of the refrigerant passing through the first and second electric expansion valves is the same regardless of whether it is cooling or heating. Therefore, the sludge adheres to the flow direction of the first and second electric expansion valves. The reliability of both electric expansion valves can be improved by setting the direction in which the amount is small.
[0016]
Further, the invention according to claim 3 is the refrigerant circuit of the invention according to claim 1, wherein supercooling is performed to perform supercooling heat exchange between the refrigerant that has exited the outdoor heat exchanger and the refrigerant that has exited the indoor heat exchanger. It is characterized by having a heat exchanger.
[0017]
According to the above configuration, the supercooling heat exchanger performs supercooling heat exchange between the supercooled refrigerant exiting the condenser and the superheated refrigerant exiting the evaporator. At this time, the direction of the refrigerant flowing out of the condenser and the evaporator is the same regardless of whether it is cooling or heating, so that the supercooling heat exchange can be performed in a counterflow. Thus, the coefficient of performance of the refrigerant circuit of the invention according to claim 1 is further improved.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
<First embodiment>
FIG. 1 is a diagram showing a refrigerant circuit in the present embodiment. This refrigerant circuit has the following configuration.
That is, the check valve 31, the outdoor heat exchanger 32, and the check valve 33 are sequentially connected in an annular manner through the refrigerant pipe so that the refrigerant flows in one direction. In addition, the check valve 34, the check valve 35, and the indoor heat exchanger 36 are sequentially connected in an annular manner through the refrigerant pipe so that the refrigerant flows in one direction. And between the check valve 31 and the outdoor heat exchanger 32 and between the check valve 34 and the indoor heat exchanger 36 are connected by a refrigerant pipe provided with a first electric expansion valve 37 that can be fully closed. . Similarly, between the check valve 33 and the outdoor heat exchanger 32 and between the check valve 35 and the indoor heat exchanger 36 are connected by a refrigerant pipe provided with a second electric expansion valve 38 that can be fully closed. To do.
Further, the refrigerant valve is connected between the check valve 31 and the check valve 33 and the discharge port of the compressor 39 via the four-way switching valve 40. On the other hand, between the check valve 34 and the check valve 35 and the suction port of the compressor 39 are connected via a four-way switching valve 40 and an accumulator 41 with a refrigerant pipe.
[0019]
Here, the first electric expansion valve 37 and the second electric expansion valve 38 have a structure using a needle valve body as shown in FIG. 2, and the high-pressure liquid refrigerant from the condenser is indicated by a broken arrow B. As described above, when supplied from the base side of the needle valve body 45, the high-pressure liquid refrigerant enters between the coil 46, the rotor 47, the shaft 48, and the casing 49. Therefore, as described above, when HFC refrigerant is used and synthetic oil is used as refrigerating machine oil, impurities such as processing oil, assembly oil, rust prevention oil or cleaning oil are dissolved or metal powder is dispersed. The high-pressure liquid refrigerant / synthetic oil that has entered the gap. Then, when a stop state or a pressure equalization state is reached, the pressure is reduced and the refrigerant and synthetic oil are evaporated, and the impurities and metal powder deposited in the refrigerant / synthetic oil form sludge to form a coil 46, rotor 47, It accumulates between the shaft 48 and the casing 49 and on the surface of the needle valve body 45.
Thus, the gap between the needle valve body 45 and the valve seat 50 is clogged, or the shaft 48 malfunctions.
[0020]
On the other hand, when the high-pressure liquid refrigerant from the condenser is supplied from the front end side of the needle valve body 45 as indicated by the solid line arrow A, sludge is formed on the needle valve body 45 due to the reattachment phenomenon of the fluid flow. Adhere to. However, the flow rate of the refrigerant flowing through the gap between the needle valve body 45 and the valve seat 50 is fast, and a strong shearing force acts to prevent the attached sludge from growing and accumulating. Further, the low-pressure two-phase refrigerant / synthetic oil in which the above-described impurities and metal powder are deposited under reduced pressure does not enter between the coil 46, the rotor 47, the shaft 48, and the casing 49.
That is, the first and second electric expansion valves 37 and 38 have a structure in which sludge hardly adheres by defining the flow direction as indicated by the arrow A.
[0021]
The four check valves 31, 33, 34, 35 and the two electric expansion valves 37, 38 are arranged together with the outdoor heat exchanger 32, the compressor 39, the four-way switching valve 40 and the accumulator 41. A unit 42 is formed. On the other hand, the indoor unit 43 is formed only by the indoor heat exchanger 36. Therefore, the indoor unit 43 in the present embodiment has a minimum auxiliary space other than the original air conditioning function.
[0022]
The refrigerant circuit having the above configuration operates as follows.
(1) Cooling operation During the cooling operation, the four-way switching valve 40 is switched as indicated by a solid line, and the first electric expansion valve 37 is fully closed, while the opening degree of the second electric expansion valve 38 is controlled.
Then, as shown by a solid line arrow (A), the refrigerant that has passed through the four-way switching valve 40 is blocked by the check valve 33, passes through the check valve 31, and is fully closed by the first electric expansion valve 37. It is blocked and flows to the outdoor heat exchanger 32 side. The refrigerant condensed by the outdoor heat exchanger 32 flows to the second electric expansion valve 38 side without being able to pass through the check valve 33 because the downstream side of the check valve 33 has a higher pressure than the upstream side, and is reduced in pressure. The
[0023]
Thus, the decompressed refrigerant is blocked by the check valve 35 and flows to the indoor heat exchanger 36 side. Then, the refrigerant evaporated in the indoor heat exchanger 36 to become a gas is blocked by the first electric expansion valve 37 and flows to the check valve 34 side, and the downstream side of the check valve 35 has a higher pressure than the upstream side. In other words, it cannot flow through the check valve 35 and flows to the four-way switching valve 40 side. Thus, the refrigerant that has passed through the four-way selector valve 40 returns to the suction port of the compressor 39 via the accumulator 41.
In this way, during the cooling operation, the refrigerant flows along the normal path indicated by the solid line arrow.
[0024]
(2) Heating operation During the heating operation, the four-way switching valve 40 is switched as indicated by the broken line, and the second electric expansion valve 38 is fully closed while the opening degree of the first electric expansion valve 37 is controlled.
Then, the refrigerant that has passed through the four-way switching valve 40 as shown by the broken arrow (b) is blocked by the check valve 34 and passes through the check valve 35, and is fully closed by the second electric expansion valve 38. It is blocked and flows to the indoor heat exchanger 36 side. The refrigerant condensed by the indoor heat exchanger 36 flows to the first electric expansion valve 37 side without being able to pass through the check valve 34 because the downstream side of the check valve 34 has a higher pressure than the upstream side, and is reduced in pressure. The
[0025]
Thus, the decompressed refrigerant is blocked by the check valve 31 and flows to the outdoor heat exchanger 32 side. Then, the refrigerant evaporated in the outdoor heat exchanger 32 and turned into gas is blocked by the second electric expansion valve 38 and flows to the check valve 33 side, and the downstream side of the check valve 31 has a higher pressure than the upstream side. In other words, it cannot flow through the check valve 31 and flows to the four-way switching valve 40 side. Thus, the refrigerant that has passed through the four-way selector valve 40 returns to the suction port of the compressor 39 via the accumulator 41.
As described above, during the heating operation, the refrigerant flows along a route indicated by a broken-line arrow.
[0026]
As a result, as can be seen from FIG. 1, the refrigerant flows through the outdoor heat exchanger 32 and the indoor heat exchanger 36 in the same direction in both the cooling operation and the heating operation. Therefore, the directional relationship between the refrigerant flow and the air flow in the indoor / outdoor heat exchangers 32 and 36 can be counterflowed regardless of whether it is during cooling or heating (counterflow), and heat exchange loss can be reduced. Further, the direction of the refrigerant flowing through each electric expansion valve 37, 38 is constant. Therefore, by setting the flow-down direction of the first electric expansion valve 37 and the second electric expansion valve 38 to be the arrow A in FIG. 2, the refrigerant can flow in a direction in which sludge is difficult to adhere. It is possible to improve the reliability.
[0027]
Thus, according to the refrigerant circuit in the present embodiment, there are four check valves and two less than the case of the conventional check valve bridge refrigerant circuit using 12 check valves as shown in FIG. With the two electric expansion valves, the counter flow of the indoor / outdoor heat exchanger and the regulation of the downward flow direction of the expansion valve can be performed in the same manner as the conventional check valve bridge refrigerant circuit. Therefore, according to the present embodiment, when the counter flow of the indoor / outdoor heat exchanger and the regulation of the downward flow direction of the expansion valve are performed, an increase in the space for installing the refrigerant circuit, an increase in cost, and a decrease in product reliability are minimized. You can hold it down.
[0028]
Further, as the two electric expansion valves 37 and 38, electric expansion valves having a structure capable of reducing the adhesion of sludge by restricting the flow direction are used, and the electric expansion valve is electrically operated either during cooling or heating. By using either one of the expansion valves 37 and 38 (that is, reducing the chance of malfunctioning to 1/2), the reduction in reliability due to clogging of the electric expansion valves 37 and 38 can be greatly reduced.
Furthermore, devices other than the indoor heat exchanger 36 can be accommodated on the outdoor unit 42 side, and the indoor unit 43 can be made compact.
[0029]
<Second Embodiment>
FIG. 3 is a diagram showing a refrigerant circuit in the present embodiment. This refrigerant circuit has a structure in which a supercooling heat exchanger 62 is provided in the refrigerant circuit shown in FIG.
That is, check valve 51, outdoor heat exchanger 52, check valve 53, check valve 54, check valve 55, indoor heat exchanger 56, first electric expansion valve 57, second electric expansion valve 58, compressor 59, the four-way switching valve 60 and the accumulator 61 are the check valve 31, the outdoor heat exchanger 32, the check valve 33, the check valve 34, the check valve 35, the indoor heat in the first embodiment shown in FIG. The exchanger 36, the first electric expansion valve 37, the second electric expansion valve 38, the compressor 39, the four-way switching valve 40, and the accumulator 41 are connected in the same manner and operate in the same manner.
[0030]
In the present embodiment, the inside of the supercooling heat exchanger 62 is located upstream of the branch point a to the second electric expansion valve 58 in the refrigerant pipe connecting the outdoor heat exchanger 52 and the check valve 53. A pipe is connected. Further, an outer pipe of the supercooling heat exchanger 62 is connected upstream of the branch point b to the first electric expansion valve 57 in the refrigerant pipe connecting the indoor heat exchanger 56 and the check valve 54. . In this way, the supercooling heat exchanger 62 performs heat exchange (supercooling heat exchange) between the superheated refrigerant and the supercooled refrigerant.
[0031]
Here, as described above, the refrigerant flows from the outdoor heat exchanger 52 toward the branch point a, while flowing from the indoor heat exchanger 56 toward the branch point b, regardless of cooling and heating, and is supercooled. The directions of passage of both refrigerants in the heat exchanger 62 are reversed. Therefore, the supercooling heat exchange performed by the supercooling heat exchanger 62 is performed by the counter flow regardless of the time of cooling / heating.
[0032]
As described above, in the refrigerant circuit according to the present embodiment, the upstream side of the branch point a in the refrigerant pipe connecting the outdoor heat exchanger 52 and the check valve 53, the indoor heat exchanger 56 and the check valve 54. Is connected to the upstream side of the branch point b in the refrigerant pipe connecting the subcooling heat exchanger 62. And the direction of the refrigerant | coolant which comes out of the outdoor heat exchanger 52 and the indoor heat exchanger 56 and passes the supercooling heat exchanger 62 is always the same. Therefore, the supercooling heat exchange can be performed by the counter flow regardless of the time of cooling or heating.
That is, according to the present embodiment, in addition to the effects of the first embodiment, it is possible to further improve the coefficient of performance by the supercooling heat exchange.
[0033]
In addition, the supercooling heat exchanger in this invention is not limited to a double tube heat exchanger.
[0034]
【The invention's effect】
As is apparent from the above, the refrigerant circuit of the invention according to claim 1 uses four check valves and two electric expansion valves to fully close the first electric expansion valve during cooling, while heating Occasionally, the second electric expansion valve is fully closed, so that the refrigerant passing through the outdoor heat exchanger, the indoor heat exchanger, and the first and second electric expansion valves can be used in both cases of cooling and heating. Since the directions are the same, the refrigerant circuit using the four check valves and the two electric expansion valves defines the counter flow of the indoor / outdoor heat exchanger and defines the downward flow direction of the expansion valve. be able to.
[0035]
That is, according to the present invention, compared with a refrigerant circuit that requires three sets of check valve bridges using four check valves (that is, twelve check valves), the storage space can be reduced and the cost can be reduced. It is possible to improve the reliability and product reliability.
[0036]
Further, the refrigerant circuit of the invention according to claim 2 has a structure in which the amount of sludge attached when the refrigerant flows in one direction as the first electric expansion valve and the second electric expansion valve is smaller than that when the refrigerant flows in the other direction. Since the electric expansion valve is used and the flow-down direction of each electric expansion valve is defined, the flow-down direction of the first and second electric expansion valves is set to the one direction with a small amount of sludge attached, so that the air-cooling can be performed. In addition, it is possible to reduce clogging and malfunction of the first and second electric expansion valves regardless of heating.
Therefore, the reliability of both electric expansion valves is improved.
[0037]
Further, the refrigerant circuit of the invention according to claim 3 is configured such that the supercooling heat exchanger causes the supercooling heat between the refrigerant that has passed through the outdoor heat exchanger and the indoor heat exchanger in the same direction regardless of whether it is cooling or heating. Since the two refrigerants passing through the supercooling heat exchanger flow in opposite directions, the supercooling heat exchange between the supercooled refrigerant from the condenser and the superheated refrigerant from the evaporator is performed. Can be carried out by counter flow regardless of cooling or heating.
Therefore, according to this invention, the coefficient of performance of the refrigerant circuit of the invention according to claim 1 can be further improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a refrigerant circuit according to the present invention.
FIG. 2 is a view showing a specific structure of the electric expansion valve in FIG. 1;
FIG. 3 is a diagram showing an embodiment different from FIG.
FIG. 4 is a view showing a conventional check valve bridge refrigerant circuit that performs counter flow of an indoor / outdoor heat exchanger and regulation of the expansion valve flow down direction.
FIG. 5 is a diagram showing a conventional check valve bridge refrigerant circuit that performs counterflow of an indoor / outdoor heat exchanger, regulation of the expansion valve flow direction, and supercooling heat exchange.
[Explanation of symbols]
31, 33, 34, 35, 51, 53, 54, 55 ... check valves,
32,52 ... outdoor heat exchanger, 36,56 ... indoor heat exchanger,
37, 57 ... first electric expansion valve, 38, 58 ... second electric expansion valve,
39,59 ... compressor, 40,60 ... four-way selector valve,
42: Outdoor unit, 43, 63 ... Indoor unit,
62 ... Supercooling heat exchanger.

Claims

The first check valve (31, 51), the outdoor heat exchanger (32, 52) and the second check valve (33, 53) are sequentially passed through the refrigerant pipe so that the direction of refrigerant flow is one direction. Connected in a ring,
The third check valve (34, 54), the fourth check valve (35, 55) and the indoor heat exchanger (36, 56) are sequentially passed through the refrigerant pipe so that the refrigerant flows in one direction. Connected in a ring,
Between the first check valve (31, 51) and the outdoor heat exchanger (32, 52) and between the third check valve (34, 54) and the indoor heat exchanger (36, 56). The first electric expansion valve (37, 57) is connected by a refrigerant pipe interposed,
Between the second check valve (33, 53) and the outdoor heat exchanger (32, 52) and between the fourth check valve (35, 55) and the indoor heat exchanger (36, 56). The second electric expansion valve (38, 58) is connected with a refrigerant pipe interposed,
Between the first check valve (31, 51) and the second check valve (33, 53) and the discharge port of the compressor (39, 59) are connected via a four-way switching valve (40, 60). Connect with refrigerant pipe,
Between the third check valve (34, 54) and the fourth check valve (35, 55) and the suction port of the compressor (39, 59), the four-way switching valve (40, 60) A refrigerant circuit, wherein the refrigerant circuit is connected via a refrigerant pipe.

The refrigerant circuit according to claim 1,
The first electric expansion valve (37, 57) and the second electric expansion valve (38, 58) have a sludge adhesion amount when the refrigerant is flowed in one direction compared to an adhesion amount when the sludge is flowed in the other direction. A refrigerant circuit characterized by having a small structure.

The refrigerant circuit according to claim 1,
A refrigerant comprising a supercooling heat exchanger (62) for performing supercooling heat exchange between the refrigerant exiting the outdoor heat exchanger (52) and the refrigerant exiting the indoor heat exchanger (56). circuit.