JP3757796B2

JP3757796B2 - Air conditioner and outdoor unit used therefor

Info

Publication number: JP3757796B2
Application number: JP2000605141A
Authority: JP
Inventors: 知巳梅田; 和広遠藤; 一也松尾; 松島　　均; 和幹浦田; 研作小国; 弘安田
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1999-03-17
Filing date: 1999-03-17
Publication date: 2006-03-22
Anticipated expiration: 2019-03-17
Also published as: TW464749B; WO2000055551A1

Description

【技術分野】
【０００１】
本発明は、冷凍サイクルまたはヒートポンプサイクルによる空気調和機に関し、特に圧縮機を起動するときの液冷媒の戻りを防止するものに好適である。
【背景技術】
【０００２】
従来、圧縮機の吸い込み側にアキュムレータ（低圧圧力容器）を配置し、圧縮機に吸入される冷媒の乾き度（即ち、液冷媒量とガス冷媒量の比率）を制御することで、圧縮機への液戻りを防止し、信頼性の確保をしている。
しかし、空気調和機のユニットの小型・軽量化、消費電力の低減（即ち、ＣＯＰ向上）、原価低減などの要求を同時に満足させるためにアキュムレータを除去した簡素化された冷凍サイクルが望ましい。
【０００３】
そして、圧縮機への液戻りを防止するため、運転の始動時又は停止直前にサイクル内の冷媒を移動させるため始動時にポンプダウン運転を行い、ポンプダウン開始時に圧縮機を所定時間だけ間欠運転する、ポンプダウン終了後で圧縮機を再起動時させるときに、所定時間だけ間欠運転を行うことが知られ、例えば特許文献１に記載されている。
【０００４】
【特許文献１】
特開平１０−１７００８０号公報
【発明の開示】
【発明が解決しようとする課題】
【０００５】
上記従来技術によるものでは、運転の始動前、停止直前あるいはデフロスト運転での切換時等に蒸発器や吸い込み管中の冷媒を凝縮器や受液器に回収するため、または低温部に冷媒が液化して溜まり次の始動時に液戻りしないようにするためポンプダウン運転を行う。しかし、この運転は圧縮機の低圧側から高圧側に冷媒を移動させるため、空気調和機の運転中に電源が切れ強制停止をした後、長期の運転休止後や周囲が低温度のために凝縮が起こっている場合、あるいは各空気調和機の設置位置の高低差等により液冷媒が溜まっている場合など、液冷媒が圧縮機の低圧側に存在している場合には、圧縮機の起動時に圧縮機への液戻りを起こす恐れがある。
そして、圧縮機の運転中に液戻りが生じると、次のような不具合が生じる場合がある。
高圧チャンバの圧縮機では、圧縮機に戻ってきた液冷媒は、直接圧縮室に吸入されるため、液圧縮が起こることで過荷重が生じ異常振動や異常音を発生させる。また、軸受け等の破損を招く。
低圧チャンバの圧縮機では、圧縮室に吸入される前に冷凍機油の油溜めの空間に入るが、液冷媒が冷凍機油を希釈し軸受けに給油される油の粘度が低下し、軸受けが焼き付きを起こす。
【０００６】
一方、高圧チャンバの圧縮機においても、圧縮過程で液冷媒が完全にガス化されずに吐出されると、圧縮室の下流に位置する冷凍機油の油溜めに流入し、ここで冷凍機油を希釈し油粘度が低下する。この場合も低圧チャンバの圧縮機と同様に軸受けが焼き付きを起こす。
圧縮機の液戻りは、空気調和機が停止中に室内機と室外機との高低差により液冷媒が室外側（圧縮機や熱源側熱交換器側）に移動したり、逆に室内側（利用側熱交換器側）に移動することとなる。そして、室外温度が低く熱源側熱交換器に冷媒が凝縮したり、逆に室内温度が低く利用側熱交換器に冷媒が凝縮したりする。
また、運転中に電源が切断された場合は、液冷媒がサイクル内のいずれかに存在するが、存在場所が不明となる。
【０００７】
本発明の目的は、上記課題を解決し、冷房運転、暖房運転、除霜運転での圧縮機起動時であっても、圧縮機への液戻り防止して信頼性を向上するものである。
また、本発明の他の目的は、冷媒の使用量を少なく、省冷媒として、さらに消費電力量等の低減による地球環境保全にも望ましいものとすることにある。
以上、本発明は上記課題の少なくとも一つを解決しようとするものである。
【課題を解決するための手段】
【０００８】
上記目的を達成するため本発明は、圧縮機の吸入側と受液器とを結ぶバイパス通路と、冷凍サイクルの通路が、開のときバイパス通路が閉となり、閉のときバイパス通路が開とされる制御弁とを備え、バイパス通路を開とした後に圧縮機を所定時間運転するものである。
これにより、バイパス通路を開とした後に圧縮機を所定時間運転するので、圧縮機の低圧側に存在する冷媒の状態に係わらず、低圧側の冷媒を移動させることができ、その後は液戻り無しに圧縮機を起動させることができ、圧縮機の信頼性を確保することができる。よって、圧縮機に吸入される冷媒の乾き度（液冷媒とガス冷媒の量の比）を調整するアキュムレータを除去して部品点数を削減し、小型化、軽量化が可能となり、使用する冷媒も少なくできる。
【０００９】
また本発明は、前記圧縮機の吸入側と前記受液器とを結ぶバイパス通路と、前記バイパス通路と前記圧縮機の吸入側との合流部に設けられた三方弁と、を備え、前記三方弁で前記バイパス通路と前記圧縮機の吸入側を連通させ、前記圧縮機、前記熱源側熱交換器又は前記利用側熱交換器のいずれか一方、及び前記バイパス通路を含んだ閉サイクルを形成し、前記閉サイクルを形成した後に前記圧縮機を所定時間運転するものである。
【００１０】
さらに本発明は、圧縮機の吸入側と受液器とを結ぶバイパス通路を備え、室外減圧装置及び室内減圧装置を開とし、圧縮機、熱源側熱交換器及び利用側熱交換器のうち圧縮機の吸い込み側となる一方の熱交換器、受液器及びバイパス通路を含んだ第１の閉サイクルと、圧縮機、熱源側熱交換器及び利用側熱交換器のうち圧縮機の吐き出し側となる他方の熱交換器、受液器及びバイパス通路を含んだ第２の閉サイクルとを形成した後に、圧縮機を所定時間運転するものである。
これにより、一方の熱交換器、受液器及びバイパス通路を含んだ第１の閉サイクルと、他方の熱交換器、受液器及びバイパス通路を含んだ第２の閉サイクルとを形成した後に、圧縮機を所定時間運転するので、低圧側及び高圧側の両方の熱交換器や配管内の冷媒を移動させることができる。よって、運転モード、冷媒状態に係わらず、圧縮機の吸い込み側での液戻りを回避できる。
【００１１】
さらに本発明は、圧縮機の吸入側と受液器とを結ぶバイパス通路を備え、バイパス通路を開とした後に圧縮機を０．５〜１．５分間に複数台の室内機の台数を乗じた時間運転するものである。
これにより、室内機が複数台ある場合でも液戻りを防止する運転を無駄に長くすることがなく、信頼性を向上できる。
さらに本発明は、上記のものにおいて、バイパス通路と圧縮機の吸入側との合流部に三方弁を設けることが望ましい。
さらに本発明は、上記のものにおいて、バイパス通路を受液器の上部となる位置に接続することが望ましい。
【００１２】
さらに本発明は、上記のものにおいて、バイパス通路に流量制御弁を設けることが望ましい。
さらに本発明は、圧縮機、四方弁、熱源側熱交換器、室外減圧装置、受液器を有する室外機において、
さらに本発明は、上記のものにおいて、冷凍サイクルに流通する冷媒を自然系冷媒とすることが望ましい。
【発明の効果】
【００１３】
本発明によれば、バイパス通路を開とした後に圧縮機を所定時間運転するので、圧縮機の低圧側に存在する冷媒の状態に係わらず、低圧側の冷媒を移動させることができ、信頼性を向上することができる。よって、アキュムレータを除去して部品点数を削減し、小型化、軽量化が可能となり、使用する冷媒も少なくできる。
【００１４】
また、本発明によれば、一方の熱交換器、受液器及びバイパス通路を含んだ第１の閉サイクルと、他方の熱交換器、受液器及びバイパス通路を含んだ第２の閉サイクルとを形成した後に、圧縮機を所定時間運転するので、低圧側及び高圧側の両方の熱交換器や配管内の冷媒を移動させることができ、運転モードに係わらず、液戻りを回避できる。
【００１５】
さらに、本発明によれば、バイパス通路を開とした後に圧縮機を０．５〜１．５分間に複数台の室内機の台数を乗じた時間運転するので、室内機が複数台ある場合でも液戻りを防止する運転を無駄に長くすることがない。
【発明を実施するための最良の形態】
【００１６】
以下、本発明の実施形態を図面により説明する。
図１は、本発明の空気調和機の冷凍サイクルのサイクル構成図を示している。冷凍サイクルは、圧縮機１、流れ方向制御弁としての四方弁２、熱源側熱交換器３、減圧装置４、受液器５、弁６、減圧装置７ａおよび減圧装置７ｂ、利用側熱交換器８ａおよび利用側熱交換器８ｂ、弁１０を順次配管で接続されている。また利用側熱交換器７ａおよび７ｂと熱源側熱交換器３は、送風機９ａおよび９ｂと送風機１２で各々送風され、熱交換している。
冷凍サイクルは大きく３つのユニットに分けられ、圧縮機１を含み破線で囲まれた部分が室外ユニット１５であり、利用側熱交換器８ａを含む破線で囲まれた部分が室内ユニット１６ａ、利用側熱交換器８ｂを含む破線で囲まれた部分が室内ユニット１６ｂであり、室内ユニット１６ａと室内ユニット１６ｂは並列に室外ユニット１５に繋がる配管１３ｆおよび配管１３ｇに接続され、マルチ型の空気調和機となっている。本例では、受液器５と圧縮機の吸い込み側配管１３ｊとを結ぶバイパス通路１４を設けており、バイパス通路１４、配管１３ｊおよび配管１３ｉの合流部に冷媒の流れ方向を制御する三方弁１１を設けていることを特徴としている。
【００１７】
本サイクル内の冷媒の流れを説明する。
冷房運転時では、図中の実線矢印方向に冷媒が流れる。圧縮機１から吐出した高温高圧のガス冷媒は、配管１３ａを通り、四方弁２に流入する。一方、四方弁２内では配管１３ａと１３ｂとが、また配管１３ｈと配管１３ｉとがそれぞれ接続されている。
四方弁２を通ったガス冷媒は配管１３ｂを通り、熱源側熱交換器３で送風機１２で送られる空気に対し放熱し、高圧の液冷媒もしくは気液二相冷媒となり受液器５に流入する。減圧装置４は全開となり絞りの役目をしていない。受液器５内に流入した冷媒は気液二相の場合は気液分離し、配管１３ｅを通り適度な乾き度状態の冷媒が室内ユニット１６ａおよび室内ユニット１６ｂに流入する。冷媒は減圧装置７ａおよび減圧装置７ｂで減圧され、室内空気温度よりも低い温度の気液二相冷媒となり、利用側熱交換器８ａおよび利用側熱交換器８ｂに流入し、各々送風機９ａおよび９ｂで送られる空気から吸熱しガス化し再び圧縮機１に戻る。
暖房運転時は、冷房運転時とは逆の方向に冷媒が流れ、図中の破線矢印の方向に冷媒が流れる。四方弁２内では、配管１３ａと１３ｈとが、また配管１３ｂと１３ｉとが接続されている。従って、利用側熱交換器８ａおよび利用側熱交換器８ｂが高圧側となり、熱源側熱交換器３は低圧側となる。
【００１８】
減圧装置としては、室内ユニット１６ａ、１６ｂ内の減圧装置７ａおよび７ｂを用いてもよいし、室外ユニット１５内の減圧装置４のいずれを用いても良い。本例では、暖房運転時には減圧装置４を用いる。なお制御性の点から室内外の減圧装置を同時に使用することはほとんどない。また、冷房運転時、暖房運転時とも三方便１１は、配管１３ｉと配管１３ｊとを接続しており、バイパス通路１４には冷媒は流れていない。
上記のような冷凍サイクルで、冷房運転や暖房運転をしているときに、電源が切られてしまった後圧縮機を再起動させる場合や、空気調和機の停止時に室外温度が低く、熱源側熱交換器３内で冷媒が凝縮している状態から暖房運転をする場合など、圧縮機１に対して低圧側となる熱源側熱交換器または利用側熱交換器では、完全に液冷媒をガス化できずに一部液冷媒の状態のまま圧縮機１に戻る現象、つまり液戻りが生じる。液戻りは、圧縮機１に対し、次のような不具合を生じさせる。例えば、高圧チャンバの圧縮機では、圧縮機に戻ってきた液冷媒は、直接圧縮室に吸入されるため、液圧縮が起こることで過荷重が生じ異常振動や異常音を発生させる。また、軸受け等の破損を招くこともある。
【００１９】
さらに、低圧チャンバの圧縮機では、圧縮機に戻ってきた液冷媒は、圧縮室に吸入される前に冷凍機油の油溜めの空間に入るが、液冷媒が冷凍機油を希釈し軸受けに給油される油の粘度が低下し、軸受けが焼き付きを起こしたりする。一方、高圧チャンバの圧縮機においても、圧縮過程で液冷媒が完全にガス化されずに吐出されると、圧縮室の下流に位置する冷凍機油の油溜めに流入し、ここで冷凍機油を希釈し油粘度が低下する。この場合も低圧チャンバの圧縮機と同様に軸受けに給油されると、軸受けが焼き付きを起こす。これらは圧縮機の信頼性に係わる重要な問題を生じさせる恐れがある。
そこで、従来は、圧縮機の上流に圧力容器（アキュムレータ）を取付け、圧縮機に戻る冷媒の乾き度を調整し、液戻りの防止および液戻りを回避している。しかし、空気調和機のユニットの小型、軽量化、消費電力の低減（即ち、成績係数ＣＯＰ向上）、原価低減などの要求を同時に満足させるためにアキュムレータを除去し、圧縮機の信頼性は維持したまま、簡素化することが必要である。
【００２０】
本実施例では、バイパス通路１４を用いて、アキュムレータの無い冷凍サイクルにおいても圧縮機起動時等での液戻りを防止し、圧縮機の信頼性を確保するものである。また、使用資源の減少、消費電力量の低減による地球環境保全にも貢献しようとするものである。
【００２１】
図２および図３に、各々冷房運転および暖房運転における圧縮機起動時の液戻り防止について説明する。
図２を用いて冷房運転を開始することを前提とした場合を説明する。冷房運転時では、利用側熱交換器８ａおよぶ利用側熱交換器８ｂ、そして配管１３ｇ，１３ｍ、１３ｎが低圧側となり、この中の冷媒が圧縮機１に吸入される。そこで、次に示すようなサイクル構成に変形し、低圧側にある冷媒を減圧装置７ａおよび７ｂの上流側（受液器５側）に移動させる。
四方弁２は配管１３ａと配管１３ｈとを、また配管１３ｂと配管１３ｉとを接続するように設定する。これは暖房運転を行うときの四方弁の設定と同じである。また三方弁１１をバイパス通路１４と配管１３ｊとを接続する設定とする。この結果、圧縮機１、配管１３ａ、四方弁２、配管１３ｈ、配管１３ｇそして室内ユニット１６及び１６ｂ、配管１３ｆ、受液器５、バイパス通路１４、三方弁１１、配管１３ｊそして再び圧縮機を接続する閉サイクルができる。このとき、減圧装置７ａおよび７ｂを全開とし圧縮機１を起動させると、利用側熱交換器８ａや８ｂ、配管１３ｍ、１３ｎや１３ｇ内の冷媒が受液器側に移動する。
室外ユニット１５と室内ユニット１６ａ、１６ｂ間の接続配管長が短いときは、受液器５に冷媒が回収できるようにし、また接続配管長が長いときは、減圧装置７ａおよび７ｂよりも受液器５側に冷媒が移動するように圧縮機１を運転する。その後、減圧装置７ａと７ｂを閉にし圧縮機１を止め、四方弁２および三方弁１１を所定の状態に切り換えて、冷房運転を開始する。そして、減圧装置７ａおよび７ｂは、圧縮機の吸い込み側が負圧に成らない程度に、徐々に開度を開けるようにするとよい。
【００２２】
次に図３を参照して暖房運転を開始することを前提とした場合を説明する。暖房運転時では、減圧装置４を用いると熱源側熱交換器３、そして配管１３ａ，１３ｂ、１３ｃが低圧側となり、この中の冷媒が圧縮機１に吸入されることになる。そこで、次に示すようなサイクル構成に変形し、低圧側にある冷媒を減圧装置４の上流側（受液器５側）に移動させる。四方弁２は配管１３ａと配管１３ｂとを、また配管１３ｈと配管１３ｉとを接続するように設定する。これは冷房運転を行うときの四方弁の設定と同じである。また三方弁１１をバイパス通路１４と配管１３ｊとを接続する設定とする。この結果、圧縮機１、配管１３ａ、四方弁２、配管１３ｂ、熱源側熱交換器３、配管１３ｃ、減圧装置４、配管１３ｄ、受液器５、バイパス通路１４、三方弁１１、配管１３ｊそして再び圧縮機を接続する閉サイクルができる。このとき、減圧装置４を全開とし圧縮機１を起動させると、熱源側熱交換器３、配管１３ａ，１３ｂや１３ｃ内の冷媒が受液器側に移動する。所定時間圧縮機１を起動した後、減圧装置４を閉にし圧縮機１を止め、四方弁２および三方弁１１を所定の状態に切り換えて、暖房運転を開始する。そして、減圧装置７ａおよび７ｂは、圧縮機の吸い込み側が負圧に成らない程度に、徐々に開度を開けるようにすることが望ましい。
バイパス通路１４内は受液器５での気液分離によりガス冷媒が流れ、バイパス通路１４を通って液戻りが生じることはない。
以上により、圧縮機の低圧側に存在する冷媒の状態に係わらず、液戻り無しに圧縮機を起動させることができ、圧縮機の信頼性を確保することができる。
【００２３】
次に各冷房運転、暖房運転や除霜運転前に、低圧側の冷媒を移動させる運転方法を冷媒移送運転と称して説明する。
図４は、バイパス通路１４上にバイパス通路１４を流れる冷媒の流量を調整するための流量調整弁１７を設けている。この流量調整弁１７は、閉め切り性があることが望ましい。
図５に示す例で、図１から図４に示した実施例の三方弁１１の機能を、２つの開閉弁１８ａおよび１８ｂで実施した場合である。即ち、冷房運転、暖房運転、除霜運転時は、開閉弁１８ａが開となり開閉弁１８ｂが閉となる。また冷媒移送運転中は、開閉弁１８ａが閉となり開閉弁１８ｂが開となる。なお、開閉弁１８ｂは流量調整機能を有していてもよい。
図６から図９に示す例では、図１から図４に示した例における四方弁２と三方弁１１の機能を一つの六方弁８１で実施した場合である。六方弁８１には、圧縮機１からの配管１３ａ、六方弁８１から熱源側熱交換器３への配管１３ｂ、六方弁８１から利用側熱交換器９ａないし９ｂへの配管１３ｊ、受液器５につながるバイパス通路８０、圧縮機１の吸い込み側配管１３ｊに接続する配管１３ｓ及び配管１３ｔの６配管が接続されている。例えば、冷房運転前の冷媒移送運転では、図６に示す例のように、六方弁８１は、配管１３ａと配管１３ｊを結び、かつ配管１３ｈと配管１３ｓとを結んでいる。また暖房運転前の冷媒移送運転では、図７に示す例のように、六方弁８１は、配管１３ａと配管１３ｂを結び、かつ配管１３ｈと配管１３ｔとを結んでいる。さらに冷房運転では、図８に示す例のように、六方弁８１は、配管１３ａと配管１３ｂを結び、かつ配管１３ｈと配管１３ｓとを結んでいる。また暖房運転では、図９に示す実施例のように、六方弁８１は、配管１３ａと配管１３ｊを結び、かつ配管１３ｂと配管１３ｔとを結んでいる。
【００２４】
図１０から図１８にさらに本発明の他の実施形態を示す。上記の例では各運転モードの低圧側に位置する熱交換器や配管内の冷媒を移動させる運転形態であった。以下に説明する例では、低圧側および高圧側の両方の熱交換器や配管内の冷媒を移動させるものである。
図１０に示すサイクル構成を図１に示したサイクルとの差違のみを示して説明する。図１の四方弁２は、冷房運転時と暖房運転時の２つのモード切換が可能であった。しかし、図６に示す四方弁１９は、冷房運転時、暖房運転時と冷媒移送運転時の３つモード切換が可能としている。よって、四方弁１９を冷媒移送運転モードに設定すると、次の２つのサイクルが同時に形成される。一方のサイクルは、圧縮機１、配管１３ａ、３モード四方弁１９、配管１３ｂ、熱源側熱交換器３、配管１３ｃ、減圧装置４、配管１３ｄ、受液器５、バイパス通路１４、三方弁１１、配管１３ｊそして再び圧縮機１で形成されるサイクルである。他方は、圧縮機１、配管１３ａ、３モード四方弁１９、配管１３ｊ、１３ｇ、１３ｍ、１３ｎ、室内ユニット１６ａ、１６ｂ、配管１３ｋ、１３ｌ、１３ｆ、１３ｅ、受液器５、バイパス通路１４、三方弁１１、配管１３ｊそして再び圧縮機１で形成されるサイクルである。
三方弁１１は、冷媒移送運転モードでありバイパス通路１４と配管１３ｊが接続されている。また減圧装置４、７ａおよび７ｂは全開である。この状態で圧縮機１を起動させると、各熱交換器と配管内の冷媒を減圧装置４、減圧装置７ａと７ｂの上流側（受液器５側）に移動させることができる。この冷媒移送運転の終了時に減圧装置４、７ａおよび７ｂを閉じ、その後冷房運転や暖房運転等の運転を開始する。その結果、運転モード、冷媒状態に係わらず、圧縮機１の吸い込み側での液戻りを回避することができる。
【００２５】
図１１から図１３は、３モード四方弁の構造と動作を示した他の実施の形態である。四方弁はチャンバ２１内にバネ２３ａ、２３ｂ、および移動通路壁２６と仕切り壁２７があり、移動通路壁２６の外壁に仕切り壁２７は取り付けられ、チャンバ２１の内壁にも接している。また移動通路壁２６の外壁には両端にバネ２３ａと２３ｂの端が接続しており、残りのもう一方はチャンバ内壁に接続している。またチャンバ２１には、圧縮機の吐出口に繋がる配管１３ａ、圧縮機の吸い込み口に繋がる配管１３ｉ、熱源側熱交換器に繋がる配管１３ｂ、利用側熱交換器に繋がる配管１３ｈが接続されている。
さらに、チャンバ２１内壁および移動通路壁２６、仕切り板２７で形成される空間２４および２５と配管１３ｉとは切換弁２２を介して圧力通路２８ａ、２８ｂ、２８ｃで接続されている。運転停止中は、移動通路壁２６はバネ２３ａと２３ｂの力の釣り合いおよび切換弁２２が圧力通路２８ａと２８ｃを接続することによる圧力バランスで図１３に示すような中立位置にある。
【００２６】
冷房運転時では、切換弁２２により圧力通路２８ａと２８ｂが接続されると、空間２４の圧力が下がり、図１３の中立の位置から、移動通路壁２６と仕切り板２７は図に対し右に移動し図１１の状態となり安定する。一方、暖房運転時では、切換弁２２により圧力通路２８ｂと２８ｃが接続されると、空間２５の圧力が下がり、図１３の中立位置から、移動通路壁２６と仕切り板２７は図に対し左に移動し第１２図の状態となり安定する。冷媒移送運転時では、切換弁２２は圧力通路２８ａと２８ｃを接続し、図１３の中立位置で安定する。従って、圧縮機の吐出口に繋がる配管１３ａを流れた冷媒は、配管１３ｂと配管１３ｈの両方に流すことができる。切換弁２２は３つの開閉弁を各々の圧力通路２８ａ、２８ｂ，２８ｃに設けると同時に、３つの圧力通路を合流させることによっても同様な機能とすることができる。
【００２７】
図１４は、図１０の例に対してさらに、他の実施の形態を示す。図１では配管１３ｉ、配管１３ｊそしてバイパス通路１４を三方弁１１を介して接続していたが、図１４の例では、３つの配管を合流点７２で合流接続させ、バイパス通路１４上および配管１３ｈ上に各々開閉弁２９ｂ、２９ａを設けている。また、四方弁２と熱源側熱交換器３の間の配管１３ｂと配管１３ｈとを結ぶ副通路７０を設け、副通路７０上に開閉弁２９ｃを設けている。開閉弁２９ａは、合流点７１から合流点７２の間に設けてあればよい。
冷房運転、暖房運転そして除霜運転時では、開閉弁２９ｂ，２９ｃを閉とし、開閉弁２９ａを開とすることで通常の運転が可能となる。また冷媒移送運転では、開閉弁２９ｂ、２９ｃを開とし、開閉弁２９ａを閉とし、四方弁２を冷房運転時のモードとする。さらに、減圧装置４、７ａおよび７ｂは全開である。この状態で圧縮機１を起動させると、各熱交換器と配管内の冷媒を減圧装置４、減圧装置７ａと７ｂの上流側（受液器５側）に移動させることができる。
冷媒移送運転の終了時に減圧装置４、７ａおよび７ｂを閉じ、その後冷房運転や暖房運転等の運転を開始する。その結果、運転モード、冷媒状態に係わらず、圧縮機１の吸い込み側での液戻りを回避することができる。
【００２８】
図１５は、図１０のさらに他の実施形態を示す。図１では配管１３ｉ、配管１３ｊそしてバイパス通路１４を三方弁１１を介して接続していたが、図１５の例では、３つの配管を合流点７２で合流して接続させる。また圧縮機１の吐出側は２つに通路に分岐し（配管１３ａ、配管１３ｑ）、各々四方弁２ａと２ｂに接続する。四方弁２ａには、配管１３ａ、配管１３ｂ、配管１３ｉと配管１３ｈが接続し、冷房運転時では、配管１３ａと配管１３ｂ、配管１３ｉと配管１３ｈが繋がり、暖房運転時では、配管１３ａと配管１３ｈ、配管１３ｂと配管１３ｉが繋がる。四方弁２ｂには、配管１３ｑ、１３ｒ、１３ｏと１３ｐが接続し、冷房運転時では、配管１３ｑと配管１３ｒ、配管１３ｏと配管１３ｐが繋がり、暖房運転時では、配管１３ｑと配管１３ｐ、配管１３ｒと配管１３ｏが繋がる。配管１３ｐの他端は合流点７３で配管１３ｇと合流する。配管１３ｏの他端は合流点７２で配管１３ｈとバイパス通路１４と合流する。配管１３ｉは合流点７４で配管１３ｏと合流する。配管１３ｒは合流点７５で配管１３ｂに合流する。また配管１３ｒ上には逆止弁３１ｂがあり、四方弁２ｂから熱源側熱交換器３の方向にのみ冷媒が流れる。さらに配管１３ｉ上には逆止弁３１ａがあり、四方弁２ａから配管１３ｏの方向のみ冷媒が流れる。
冷媒移送運転では、四方弁２ａを冷房運転モード、四方弁２ｂを暖房運転モードとする。また減圧装置４、７ａおよび７ｂは全開である。この状態で圧縮機１を起動させると、各熱交換器と配管内の冷媒を減圧装置４、減圧装置７ａと７ｂの上流側（受液器５側）に移動させることができる。この冷媒移送運転の終了時に減圧装置４、７ａおよび７ｂを閉じ、その後冷房運転や暖房運転等の運転を開始する。その結果、運転モード、冷媒状態に係わらず、圧縮機１の吸い込み側での液戻りを回避することができる。
【００２９】
図１６は、図１５に示したサイクルで、冷房運転を行うときの冷媒の流れを示している。また図１７は、図１５に示したサイクルで、暖房運転を行うときの冷媒の流れを示している。
図１８は、図５に示したサイクルで、図５中のバイパス通路１４に相当する図１４中のバイパス通路３３の圧縮機側の接続位置を、圧縮機の吸い込み側配管ではなく、圧縮機の圧縮過程の途中とした場合のサイクル構成である。このサイクルでは、バイパス通路３３を利用して、冷房運転時、暖房運転時において、ガスインジェクションサイクルを構成することができる。
図１９は、図１８に示すサイクル上の圧縮機１として用いる圧縮機の例を示している。バイパス通路３３は、固定スクロール４４と鏡板４５で形成される圧縮室５０に接続されている。
図２０は、受液器の構造の例を示す。受液器５は底部中央に仕切り板６４を有し、配管６２ａおよび配管６２ｂが挿入されている。配管６２ａと配管６２ｂの端部は仕切り板６４の上端よりも低い位置にあり、各々の配管から流出する冷媒流の相互干渉あが生じないようにしている。また受液器５は内部で二相冷媒を気液の密度差、即ち重力の影響により、上層にガス相、下層に液相とに気液分離する。
受液器５内に挿入されているそれぞれの配管６２ａ、６２ｂには、受液器５から流出する冷媒流の乾き度（全冷媒質量流量に対するガス冷媒の質量流量割合）を適度にするためのガス抜き孔６３ａ、６３ｂがある。また、圧縮機の吸い込み側に繋がるバイパス通路６１の端部は、受液器５の上部に取り付けられガス冷媒のみを取り出す。
以上の説明では、冷房運転、暖房運転や除霜運転前および除霜運転中の圧縮機の再起動時後に冷媒移送運転を行うとしているが、冷媒移送運転は各運転の終了直前に行ってもよい。この場合は受液器への冷媒回収運転と同じになる。
【００３０】
特に可燃性の冷媒などは、運転終了直前に冷媒移送運転を行うことで、室外機に冷媒を集められるので、室内への冷媒の漏洩などを防ぎ、また漏洩した場合においても最小限度の漏洩量に押さえることが可能となる。室外側の熱源側熱交換器と室内側の利用側熱交換器を各々含む２つの閉サイクルを同時に構成でき、冷媒移送運転を行うことが好ましいが、少なくとも室内側の利用側熱交換器を含む閉サイクルを構成し、冷媒移送運転を行うことが望ましい。
上記の例は、冷媒の種類及び油の種類、スクロール圧縮機、レシプロ圧縮機、ロータリー圧縮機など圧縮機の形式に係わらず液戻りを解消できるので、特にＲ４０７ＣやＲ４１０Ａを代表とするＨＦＣ系冷媒、または二酸化炭素やＨＣ系冷媒などの自然系冷媒とした場合は、冷媒の使用量を少なくできるので、地球環境保全に望ましい。さらに、スクロール圧縮機とすれば、効率がより向上して一層地球環境保全に望ましいものとすることができる。
また、一定速機、インバータ駆動の圧縮機でも可能であり、圧縮機内の電動機部が冷媒吸入側にある低圧チャンバ方式の圧縮機においても、また圧縮機内の電動機部が冷媒吐出側にある高圧チャンバ方式の圧縮機においても有効であるので、特にインバータ駆動、高圧チャンバ方式の圧縮機とすれば要求負荷に対して効率良く運転できるので、より一層、消費電力量等の低減ができ地球環境保全に望ましいものとすることができる。
【００３１】
以上、アキュムレータ付きサイクルをレシーバ付きサイクルにすることで、例えば冷房運転では、レシーバに液冷媒を溜める構成となり、室外機の熱源側熱交換器で凝縮した液冷媒をレシーバに移動し、液冷媒の溜まっていた熱交換器部分も二相域で使用できるため熱交換器の有効活用が図れ、その結果、凝縮圧力が下がり、また圧縮仕事が減ることで、同一冷房能力で消費電力低減ができる。
例えば、冷房能力１４ｋＷの室外機１台、室内機１台の機種では、冷房ＣＯＰ（成績係数＝冷房能力／消費電力）を約２．６から約２．８〜２．９に約１０％向上できる。また暖房運転時も同様な効果が得られる。
従来、レシーバ付きサイクルにおいて、液戻りに対する圧縮機の信頼性を確保するために、アキュムレータも搭載する必要がある。しかし、本発明により、アキュムレータ無しのレシーバ付きサイクルとすることが可能である。その結果、例えば冷房能力１４ｋＷの室外機では、アキュムレータとレシーバの両方を搭載した場合、室外機の幅が約１．２ｍの寸法となるのを、本発明によれば約１．０〜１．１ｍに約１０％小型化することが可能となる。
【００３２】
さらに、例えば、冷房能力１４ｋＷの室外機１台、室内機１台の機種では、アキュムレータ付きサイクルをレシーバ付きサイクルにすることで、凝縮器として働く熱交換器に溜まる液冷媒量を削減できるので、冷媒封入量を５．６ｋｇから約４．０〜４．５ｋｇに約２０％削減（省冷媒化）でき、またアキュムレータとレシーバの両方を搭載した場合、冷媒封入量が約４．５〜５．０ｋｇとなるのを、本発明により、アキュムレータを配置しなくてよいので、冷媒封入量を約４〜４．５ｋｇにできることで、省冷媒化の効果を維持できる。
【００３３】
室内機側の閉サイクルの冷媒移送運転の運転時間は、室外熱交換器と室内熱交換器の間の配管長や、室内機の台数によっても異なる。例えば、室外機１台と室内機１台で、室外熱交換器と室内熱交換器間の配管長が５ｍの時、運転時間は０．５〜１．５分間程度が望ましい。また、それ以上の配管長の場合は、
運転時間(分)＝配管長(ｍ)／５(ｍ)×０．５〜１．５(分)
の時間、運転することが良く、室内機が複数台ある場合は、
運転時間(分)＝室内機台数(台)×０．５〜１．５(分/台)
の時間、運転することが望ましい。
さらに、室外機側の閉サイクルの冷媒移送運転の運転時間は、大概０．５〜１．５分間程度が望ましい。
【図面の簡単な説明】
【００３４】
【図１】図１は、本発明の一実施例である受液器−圧縮機間バイパス通路を設けた空気調和機のサイクル図。
【図２】図２は、図１の空気調和機における冷房運転前の冷媒移送運転時のサイクル構成と冷媒の流れを示すサイクル図。
【図３】図３は、図１の空気調和機における暖房運転前の冷媒移送運転時のサイクル構成と冷媒の流れを示すサイクル図。
【図４】図４は、図１の空気調和機における受液器−圧縮機間バイパス通路に流量制御弁を設けたサイクルを示すサイクル図。
【図５】図５は、図１の空気調和機における三方弁の代わりに開閉弁を用いたサイクルを示すサイクル図。
【図６】図６は、図１の空気調和機における四方弁と三方弁の代わりに六方弁を用いたサイクル構成において、冷房運転前の冷媒移送運転時の冷媒の流れを示すサイクル図。
【図７】図７は、図６の空気調和機における暖房運転前の冷媒移送運転時の冷媒の流れを示すサイクル図。
【図８】図８は、図６の空気調和機における冷房運転時の冷媒の流れを示すサイクル図。
【図９】図９は、図６の空気調和機における暖房運転時の冷媒の流れを示すサイクル図。
【図１０】図１０は、３モード四方弁を用いた冷房運転前の両方同時冷媒移送運転時のサイクル構成と冷媒の流れを示すサイクル図。
【図１１】図１１は、３モード四方弁の冷房運転時の構造と冷媒の流れを示す図。
【図１２】第１２図は、３モード四方弁の暖房運転時の構造と冷媒の流れを示す図。
【図１３】図１３は、３モード四方弁の冷媒移送運転時の構造と冷媒の流れを示す図。
【図１４】図１４は、図１０の空気調和機における３モード四方弁の代わりに開閉弁を用いた他の実施例であるサイクル構成と冷媒移送運転時の冷媒の流れを示すサイクル図。
【図１５】図１５は、図１０の空気調和機における３モード四方弁の代わりに四方弁２個を用いた他の実施例であるサイクル構成と冷媒移送運転時の冷媒の流れを示すサイクル図。
【図１６】図１６は、図１４の空気調和機における冷房運転時の冷媒の流れを示すサイクル図。
【図１７】図１７は、図１４の空気調和機における暖房運転時の冷媒の流れを示すサイクル図。
【図１８】図１８は、図１の一実施例であるサイクル上のバイパス通路の一端を圧縮機の圧縮過程中間に接続した時のサイクル構成と冷媒移送運転時の冷媒の流れを示すサイクル図。
【図１９】図１９は、図１８のサイクルに使用する圧縮機を示す断面図。
【図２０】図２０は、一実施例に使用する受液器構造を示す断面図。
【符号の説明】
【００３５】
１…圧縮機、２…四方弁、３…熱源側熱交換器、４…減圧装置、５…受液器、７…減圧装置、８…利用側熱交換器、１１…三方弁、１４…バイパス通路。【Technical field】
[0001]
The present invention relates to an air conditioner using a refrigeration cycle or a heat pump cycle, and is particularly suitable for preventing the return of liquid refrigerant when starting a compressor.
[Background]
[0002]
Conventionally, an accumulator (low pressure container) is arranged on the suction side of the compressor, and the dryness of the refrigerant sucked into the compressor (that is, the ratio of the amount of liquid refrigerant to the amount of gas refrigerant) is controlled. This prevents liquid return and ensures reliability.
However, a simplified refrigeration cycle in which an accumulator is removed is desirable in order to simultaneously satisfy the demands for reducing the size and weight of the air conditioner unit, reducing power consumption (ie, improving COP), and reducing costs.
[0003]
In order to prevent the liquid from returning to the compressor, the pump down operation is performed at the start to move the refrigerant in the cycle at the start of the operation or immediately before the stop, and the compressor is intermittently operated for a predetermined time at the start of the pump down. , It is known to perform intermittent operation for a predetermined time when the compressor is restarted after the pump is down, for example, Patent Document 1 It is described in.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-170080
DISCLOSURE OF THE INVENTION
[Problems to be solved by the invention]
[0005]
According to the above prior art, the refrigerant in the evaporator or the suction pipe is collected in the condenser or the liquid receiver before starting the operation, immediately before stopping, or at the time of switching in the defrost operation, or the refrigerant is liquefied in the low temperature part. In order to prevent the liquid from returning at the next start-up, the pump down operation is performed. However, since this operation moves the refrigerant from the low pressure side to the high pressure side of the compressor, after the power is cut off during the air conditioner operation and it is forcibly stopped, it is condensed after a long period of shutdown or because the surroundings are low in temperature. If the liquid refrigerant is present on the low pressure side of the compressor, such as when there is a liquid refrigerant accumulated due to the height difference of the installation position of each air conditioner, etc. There is a risk of liquid return to the compressor.
And when a liquid return arises during a driving | running of a compressor, the following malfunctions may arise.
In the compressor of the high pressure chamber, the liquid refrigerant that has returned to the compressor is directly sucked into the compression chamber, so that liquid compression occurs, resulting in overload and abnormal vibration and noise. In addition, the bearings and the like are damaged.
In the compressor of the low-pressure chamber, the refrigerant enters the oil reservoir space before being sucked into the compression chamber, but the liquid refrigerant dilutes the refrigerator oil and the viscosity of the oil supplied to the bearing is lowered, and the bearing is seized. Wake up.
[0006]
On the other hand, in the compressor of the high-pressure chamber, if the liquid refrigerant is discharged without being completely gasified during the compression process, it flows into the oil reservoir for the refrigerating machine oil located downstream of the compression chamber, where the refrigerating machine oil is diluted. The oil viscosity decreases. In this case as well, the bearing is seized in the same manner as the compressor in the low pressure chamber.
When the air conditioner is stopped, the liquid return of the compressor can be caused by the liquid refrigerant moving to the outdoor side (compressor or heat source side heat exchanger side) due to the difference in height between the indoor unit and the outdoor unit, It will move to the use side heat exchanger side). Then, the outdoor temperature is low and the refrigerant condenses in the heat source side heat exchanger, or conversely, the indoor temperature is low and the refrigerant condenses in the use side heat exchanger.
In addition, when the power is cut off during operation, the liquid refrigerant is present anywhere in the cycle, but the location is unknown.
[0007]
The object of the present invention is to solve the above-mentioned problems, and to improve the reliability by preventing liquid return to the compressor even when the compressor is started in the cooling operation, heating operation, and defrosting operation.
Another object of the present invention is to reduce the amount of refrigerant used, to make it desirable for conservation of the global environment by reducing the amount of power consumption and the like as a refrigerant saving.
As described above, the present invention is intended to solve at least one of the above problems.
[Means for Solving the Problems]
[0008]
In order to achieve the above object, according to the present invention, when the bypass passage connecting the suction side of the compressor and the receiver and the passage of the refrigeration cycle are opened, the bypass passage is closed, and when closed, the bypass passage is opened. And the control valve is operated for a predetermined time after the bypass passage is opened.
As a result, since the compressor is operated for a predetermined time after the bypass passage is opened, the refrigerant on the low pressure side can be moved regardless of the state of the refrigerant existing on the low pressure side of the compressor, and there is no liquid return thereafter. Thus, the compressor can be started, and the reliability of the compressor can be ensured. Therefore, it is possible to reduce the number of parts by removing the accumulator that adjusts the dryness of the refrigerant sucked into the compressor (ratio of the amount of liquid refrigerant to gas refrigerant). Less.
[0009]
The present invention also includes a bypass passage connecting the suction side of the compressor and the liquid receiver; A three-way valve provided at a junction between the bypass passage and the suction side of the compressor, and the bypass passage and the suction side of the compressor are communicated with each other by the three-way valve; A closed cycle including the compressor, one of the heat source side heat exchanger or the use side heat exchanger, and the bypass passage. Forming, The compressor is operated for a predetermined time after the closed cycle is formed.
[0010]
The present invention further includes a bypass passage connecting the suction side of the compressor and the liquid receiver, and the outdoor pressure reducing device and the indoor pressure reducing device are opened, and the compressor, the heat source side heat exchanger, and the use side heat exchanger are compressed. A first closed cycle including one heat exchanger, a receiver, and a bypass passage on the suction side of the compressor, and a discharge side of the compressor among the compressor, the heat source side heat exchanger, and the utilization side heat exchanger; After forming the other heat exchanger, the liquid receiver and the second closed cycle including the bypass passage, the compressor is operated for a predetermined time.
Thus, after forming a first closed cycle including one heat exchanger, a receiver and a bypass passage, and a second closed cycle including the other heat exchanger, a receiver and a bypass passage. Since the compressor is operated for a predetermined time, both the low-pressure side and high-pressure side heat exchangers and the refrigerant in the pipe can be moved. Therefore, liquid return on the suction side of the compressor can be avoided regardless of the operation mode and the refrigerant state.
[0011]
Furthermore, the present invention includes a bypass passage that connects the suction side of the compressor and the liquid receiver, and after the bypass passage is opened, the compressor is multiplied by the number of indoor units in 0.5 to 1.5 minutes. Drive for a long time.
As a result, even when there are a plurality of indoor units, the operation for preventing liquid return is not unnecessarily prolonged, and the reliability can be improved.
Further, in the present invention, it is preferable that a three-way valve is provided at a junction between the bypass passage and the suction side of the compressor.
Furthermore, in the present invention, it is preferable that the bypass passage is connected to a position that is an upper portion of the liquid receiver.
[0012]
Furthermore, in the present invention, it is desirable to provide a flow control valve in the bypass passage.
Furthermore, the present invention relates to an outdoor unit having a compressor, a four-way valve, a heat source side heat exchanger, an outdoor pressure reducing device, and a liquid receiver.
Furthermore, in the present invention, it is preferable that the refrigerant circulating in the refrigeration cycle is a natural refrigerant.
【The invention's effect】
[0013]
According to the present invention, since the compressor is operated for a predetermined time after the bypass passage is opened, the refrigerant on the low-pressure side can be moved regardless of the state of the refrigerant existing on the low-pressure side of the compressor. Can be improved. Therefore, the accumulator is removed to reduce the number of parts, and the size and weight can be reduced, and the amount of refrigerant used can be reduced.
[0014]
Further, according to the present invention, the first closed cycle including one heat exchanger, the liquid receiver and the bypass passage, and the second closed cycle including the other heat exchanger, the liquid receiver and the bypass passage. Since the compressor is operated for a predetermined time after the formation, the refrigerant in both the low-pressure side and the high-pressure side heat exchanger and the refrigerant in the pipe can be moved, and liquid return can be avoided regardless of the operation mode.
[0015]
Furthermore, according to the present invention, after the bypass passage is opened, the compressor is operated for a period of 0.5 to 1.5 minutes multiplied by the number of indoor units, so even when there are multiple indoor units The operation for preventing the liquid return is not unnecessarily prolonged.
BEST MODE FOR CARRYING OUT THE INVENTION
[0016]
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a cycle configuration diagram of a refrigeration cycle of an air conditioner of the present invention. The refrigeration cycle includes a compressor 1, a four-way valve 2 as a flow direction control valve, a heat source side heat exchanger 3, a pressure reducing device 4, a liquid receiver 5, a valve 6, a pressure reducing device 7a and a pressure reducing device 7b, and a use side heat exchanger. 8a, the use side heat exchanger 8b, and the valve 10 are sequentially connected by piping. The use side heat exchangers 7a and 7b and the heat source side heat exchanger 3 are blown by the blowers 9a and 9b and the blower 12, respectively, to exchange heat.
The refrigeration cycle is roughly divided into three units. The portion surrounded by the broken line including the compressor 1 is the outdoor unit 15, and the portion surrounded by the broken line including the use side heat exchanger 8a is the indoor unit 16a. A portion surrounded by a broken line including the heat exchanger 8b is the indoor unit 16b, and the indoor unit 16a and the indoor unit 16b are connected in parallel to the pipe 13f and the pipe 13g connected to the outdoor unit 15, and the multi-type air conditioner It has become. In this example, a bypass passage 14 that connects the liquid receiver 5 and the suction side piping 13j of the compressor is provided, and a three-way valve 11 that controls the flow direction of the refrigerant at the junction of the bypass passage 14, the piping 13j, and the piping 13i. It is characterized by providing.
[0017]
The flow of the refrigerant in this cycle will be described.
During the cooling operation, the refrigerant flows in the direction of the solid arrow in the figure. The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the four-way valve 2 through the pipe 13a. On the other hand, in the four-way valve 2, the pipes 13a and 13b and the pipe 13h and the pipe 13i are connected, respectively.
The gas refrigerant that has passed through the four-way valve 2 passes through the pipe 13b, dissipates heat to the air sent by the blower 12 in the heat source side heat exchanger 3, and flows into the receiver 5 as high-pressure liquid refrigerant or gas-liquid two-phase refrigerant. . The decompression device 4 is fully open and does not serve as a throttle. When the refrigerant flowing into the liquid receiver 5 is gas-liquid two-phase, the refrigerant is separated into gas and liquid, and the refrigerant in an appropriately dry state flows into the indoor unit 16a and the indoor unit 16b through the pipe 13e. The refrigerant is decompressed by the decompression device 7a and the decompression device 7b, becomes a gas-liquid two-phase refrigerant having a temperature lower than the indoor air temperature, flows into the use side heat exchanger 8a and the use side heat exchanger 8b, and blowers 9a and 9b, respectively. The heat is absorbed from the air sent by the gas and gasified to return to the compressor 1 again.
During the heating operation, the refrigerant flows in the direction opposite to that during the cooling operation, and the refrigerant flows in the direction of the broken line arrow in the figure. In the four-way valve 2, pipes 13a and 13h and pipes 13b and 13i are connected. Therefore, the use side heat exchanger 8a and the use side heat exchanger 8b are on the high pressure side, and the heat source side heat exchanger 3 is on the low pressure side.
[0018]
As the decompression device, the decompression devices 7a and 7b in the indoor units 16a and 16b may be used, or any of the decompression devices 4 in the outdoor unit 15 may be used. In this example, the decompression device 4 is used during the heating operation. From the point of controllability, the indoor and outdoor decompressors are rarely used at the same time. Further, in the cooling operation and the heating operation, the three-way flight 11 connects the pipe 13 i and the pipe 13 j, and no refrigerant flows through the bypass passage 14.
When the compressor is restarted after the power is turned off during the cooling operation or heating operation in the refrigeration cycle as described above, the outdoor temperature is low when the air conditioner is stopped, and the heat source side When heating operation is performed from the state in which the refrigerant is condensed in the heat exchanger 3, the heat source side heat exchanger or the use side heat exchanger on the low pressure side with respect to the compressor 1 completely gasses the liquid refrigerant. Phenomenon that returns to the compressor 1 in the state of a part of the liquid refrigerant without being converted to liquid, that is, liquid return occurs. The liquid return causes the following problems for the compressor 1. For example, in a compressor of a high-pressure chamber, liquid refrigerant that has returned to the compressor is directly sucked into the compression chamber. Therefore, liquid compression occurs, resulting in overload and abnormal vibration and noise. Moreover, a bearing etc. may be damaged.
[0019]
Furthermore, in the compressor of the low pressure chamber, the liquid refrigerant that has returned to the compressor enters the oil reservoir space of the refrigerating machine oil before being sucked into the compression chamber, but the liquid refrigerant dilutes the refrigerating machine oil and is supplied to the bearing. The viscosity of the oil will decrease and the bearing will seize. On the other hand, in the compressor of the high-pressure chamber, if the liquid refrigerant is discharged without being completely gasified during the compression process, it flows into the oil reservoir for the refrigerating machine oil located downstream of the compression chamber, where the refrigerating machine oil is diluted. The oil viscosity decreases. Also in this case, when the bearing is supplied with oil like the compressor of the low pressure chamber, the bearing is seized. These can cause significant problems with compressor reliability.
Therefore, conventionally, a pressure vessel (accumulator) is attached upstream of the compressor, and the dryness of the refrigerant returning to the compressor is adjusted to prevent liquid return and avoid liquid return. However, the accumulator was removed in order to satisfy the requirements of air conditioner units that were smaller, lighter, reduced power consumption (ie, improved coefficient of performance COP), and reduced costs, and the reliability of the compressor was maintained. It is necessary to keep it simple.
[0020]
In the present embodiment, the bypass passage 14 is used to prevent the liquid from returning when the compressor is started even in a refrigeration cycle without an accumulator, thereby ensuring the reliability of the compressor. It also seeks to contribute to global environmental conservation by reducing resources used and reducing power consumption.
[0021]
FIG. 2 and FIG. 3 describe the prevention of liquid return when the compressor is started in the cooling operation and the heating operation, respectively.
The case where it presupposes starting a cooling operation using FIG. 2 is demonstrated. During the cooling operation, the use side heat exchanger 8a and the use side heat exchanger 8b and the pipes 13g, 13m, and 13n are on the low pressure side, and the refrigerant therein is sucked into the compressor 1. Therefore, the cycle configuration is changed as shown below, and the refrigerant on the low pressure side is moved to the upstream side (the liquid receiver 5 side) of the decompression devices 7a and 7b.
The four-way valve 2 is set so that the pipe 13a and the pipe 13h are connected, and the pipe 13b and the pipe 13i are connected. This is the same as the setting of the four-way valve when performing the heating operation. The three-way valve 11 is set to connect the bypass passage 14 and the pipe 13j. As a result, the compressor 1, the pipe 13a, the four-way valve 2, the pipe 13h, the pipe 13g, the indoor units 16 and 16b, the pipe 13f, the liquid receiver 5, the bypass passage 14, the three-way valve 11, the pipe 13j, and the compressor are connected again. A closed cycle is possible. At this time, when the decompression devices 7a and 7b are fully opened and the compressor 1 is started, the refrigerant in the use side heat exchangers 8a and 8b, the pipes 13m, 13n, and 13g moves to the receiver side.
When the connection pipe length between the outdoor unit 15 and the indoor units 16a and 16b is short, the refrigerant can be collected in the liquid receiver 5, and when the connection pipe length is long, the liquid receiver is more than the decompression devices 7a and 7b. The compressor 1 is operated so that the refrigerant moves to the 5 side. Thereafter, the decompression devices 7a and 7b are closed, the compressor 1 is stopped, the four-way valve 2 and the three-way valve 11 are switched to a predetermined state, and the cooling operation is started. And it is good for the decompression devices 7a and 7b to gradually open the opening so that the suction side of the compressor does not become negative pressure.
[0022]
Next, a case where it is assumed that the heating operation is started will be described with reference to FIG. During the heating operation, when the decompression device 4 is used, the heat source side heat exchanger 3 and the pipes 13a, 13b, and 13c are on the low pressure side, and the refrigerant therein is sucked into the compressor 1. Therefore, the cycle configuration is changed as shown below, and the refrigerant on the low pressure side is moved to the upstream side of the decompression device 4 (the liquid receiver 5 side). The four-way valve 2 is set so that the pipe 13a and the pipe 13b are connected, and the pipe 13h and the pipe 13i are connected. This is the same as the setting of the four-way valve when performing the cooling operation. The three-way valve 11 is set to connect the bypass passage 14 and the pipe 13j. As a result, the compressor 1, the pipe 13a, the four-way valve 2, the pipe 13b, the heat source side heat exchanger 3, the pipe 13c, the pressure reducing device 4, the pipe 13d, the liquid receiver 5, the bypass passage 14, the three-way valve 11, the pipe 13j and A closed cycle to connect the compressor again is possible. At this time, when the decompression device 4 is fully opened and the compressor 1 is started, the refrigerant in the heat source side heat exchanger 3, the pipes 13a, 13b, and 13c moves to the receiver side. After starting the compressor 1 for a predetermined time, the decompression device 4 is closed, the compressor 1 is stopped, the four-way valve 2 and the three-way valve 11 are switched to a predetermined state, and the heating operation is started. And it is desirable for the decompression devices 7a and 7b to gradually open the opening so that the suction side of the compressor does not become negative pressure.
In the bypass passage 14, gas refrigerant flows by gas-liquid separation in the liquid receiver 5, and liquid return does not occur through the bypass passage 14.
As described above, regardless of the state of the refrigerant existing on the low pressure side of the compressor, the compressor can be started without liquid return, and the reliability of the compressor can be ensured.
[0023]
Next, an operation method for moving the low-pressure side refrigerant before each cooling operation, heating operation and defrosting operation will be referred to as a refrigerant transfer operation.
In FIG. 4, a flow rate adjusting valve 17 for adjusting the flow rate of the refrigerant flowing through the bypass passage 14 is provided on the bypass passage 14. It is desirable that the flow rate adjusting valve 17 has a closeability.
In the example shown in FIG. 5, the function of the three-way valve 11 of the embodiment shown in FIGS. 1 to 4 is implemented by two on-off valves 18a and 18b. That is, at the time of cooling operation, heating operation, and defrosting operation, the on-off valve 18a is opened and the on-off valve 18b is closed. During the refrigerant transfer operation, the on-off valve 18a is closed and the on-off valve 18b is opened. The on-off valve 18b may have a flow rate adjusting function.
In the example shown in FIGS. 6 to 9, the functions of the four-way valve 2 and the three-way valve 11 in the example shown in FIGS. 1 to 4 are implemented by a single six-way valve 81. The six-way valve 81 includes a pipe 13a from the compressor 1, a pipe 13b from the six-way valve 81 to the heat source side heat exchanger 3, a pipe 13j from the six-way valve 81 to the use side heat exchangers 9a to 9b, and the receiver 5 Are connected to the bypass passage 80, the pipe 13s connected to the suction side pipe 13j of the compressor 1, and the pipe 13t. For example, in the refrigerant transfer operation before the cooling operation, as in the example shown in FIG. 6, the six-way valve 81 connects the pipe 13a and the pipe 13j and connects the pipe 13h and the pipe 13s. In the refrigerant transfer operation before the heating operation, as in the example shown in FIG. 7, the six-way valve 81 connects the pipe 13a and the pipe 13b and connects the pipe 13h and the pipe 13t. Further, in the cooling operation, as in the example shown in FIG. 8, the six-way valve 81 connects the pipe 13a and the pipe 13b, and connects the pipe 13h and the pipe 13s. In the heating operation, as in the embodiment shown in FIG. 9, the six-way valve 81 connects the pipe 13a and the pipe 13j, and connects the pipe 13b and the pipe 13t.
[0024]
10 to 18 show another embodiment of the present invention. In the above example, the operation mode is such that the heat exchanger located on the low pressure side of each operation mode and the refrigerant in the pipe are moved. In the example described below, both the low-pressure side and high-pressure side heat exchangers and the refrigerant in the piping are moved.
The cycle configuration shown in FIG. 10 will be described by showing only the difference from the cycle shown in FIG. The four-way valve 2 in FIG. 1 can be switched between two modes during cooling operation and heating operation. However, the four-way valve 19 shown in FIG. 6 can be switched between three modes during the cooling operation, the heating operation, and the refrigerant transfer operation. Therefore, when the four-way valve 19 is set to the refrigerant transfer operation mode, the following two cycles are formed simultaneously. One cycle includes a compressor 1, a pipe 13a, a three-mode four-way valve 19, a pipe 13b, a heat source side heat exchanger 3, a pipe 13c, a pressure reducing device 4, a pipe 13d, a liquid receiver 5, a bypass passage 14, and a three-way valve 11. , A cycle formed by the pipe 13j and the compressor 1 again. The other is the compressor 1, the pipe 13a, the three-mode four-way valve 19, the pipes 13j, 13g, 13m, 13n, the indoor units 16a, 16b, the pipes 13k, 13l, 13f, 13e, the liquid receiver 5, the bypass passage 14, three-way This is a cycle formed by the valve 11, the pipe 13 j and the compressor 1 again.
The three-way valve 11 is in the refrigerant transfer operation mode, and the bypass passage 14 and the pipe 13j are connected. The decompression devices 4, 7a and 7b are fully open. When the compressor 1 is started in this state, each heat exchanger and the refrigerant in the pipe can be moved to the upstream side (the receiver 5 side) of the decompression device 4 and the decompression devices 7a and 7b. At the end of the refrigerant transfer operation, the decompression devices 4, 7a and 7b are closed, and thereafter operations such as cooling operation and heating operation are started. As a result, liquid return on the suction side of the compressor 1 can be avoided regardless of the operation mode and the refrigerant state.
[0025]
11 to 13 are other embodiments showing the structure and operation of a three-mode four-way valve. The four-way valve has springs 23 a and 23 b in the chamber 21, and a moving passage wall 26 and a partition wall 27. The partition wall 27 is attached to the outer wall of the moving passage wall 26 and is in contact with the inner wall of the chamber 21. Further, the ends of the springs 23a and 23b are connected to both ends of the outer wall of the moving passage wall 26, and the other end is connected to the inner wall of the chamber. The chamber 21 is connected with a pipe 13a connected to the discharge port of the compressor, a pipe 13i connected to the suction port of the compressor, a pipe 13b connected to the heat source side heat exchanger, and a pipe 13h connected to the use side heat exchanger. .
Further, the spaces 24 and 25 formed by the inner wall of the chamber 21, the moving passage wall 26 and the partition plate 27 and the pipe 13 i are connected to each other by pressure passages 28 a, 28 b and 28 c through the switching valve 22. When the operation is stopped, the moving passage wall 26 is in a neutral position as shown in FIG. 13 due to the balance of the forces of the springs 23a and 23b and the pressure balance due to the switching valve 22 connecting the pressure passages 28a and 28c.
[0026]
During the cooling operation, when the pressure passages 28a and 28b are connected by the switching valve 22, the pressure in the space 24 decreases, and the moving passage wall 26 and the partition plate 27 move to the right from the neutral position in FIG. However, the state becomes stable as shown in FIG. On the other hand, during the heating operation, when the pressure passages 28b and 28c are connected by the switching valve 22, the pressure in the space 25 decreases, and the moving passage wall 26 and the partition plate 27 are moved to the left with respect to the drawing from the neutral position in FIG. It moves and stabilizes as shown in FIG. During the refrigerant transfer operation, the switching valve 22 connects the pressure passages 28a and 28c and is stabilized at the neutral position in FIG. Therefore, the refrigerant that has flowed through the pipe 13a connected to the discharge port of the compressor can flow into both the pipe 13b and the pipe 13h. The switching valve 22 can have the same function by providing three on-off valves in the respective pressure passages 28a, 28b, 28c and simultaneously merging the three pressure passages.
[0027]
FIG. 14 shows another embodiment in addition to the example of FIG. In FIG. 1, the pipe 13i, the pipe 13j, and the bypass passage 14 are connected via the three-way valve 11. However, in the example of FIG. 14, the three pipes are joined at the junction 72, and the bypass passage 14 and the pipe 13h are connected. On-off valves 29b and 29a are provided above. Further, a sub passage 70 that connects the pipe 13 b and the pipe 13 h between the four-way valve 2 and the heat source side heat exchanger 3 is provided, and an on-off valve 29 c is provided on the sub passage 70. The on-off valve 29a may be provided between the junction 71 and the junction 72.
During cooling operation, heating operation, and defrosting operation, normal operation is possible by closing the on-off valves 29b and 29c and opening the on-off valve 29a. In the refrigerant transfer operation, the open / close valves 29b and 29c are opened, the open / close valve 29a is closed, and the four-way valve 2 is set to the mode for the cooling operation. Furthermore, the decompression devices 4, 7a and 7b are fully open. When the compressor 1 is started in this state, each heat exchanger and the refrigerant in the pipe can be moved to the upstream side (the receiver 5 side) of the decompression device 4 and the decompression devices 7a and 7b.
At the end of the refrigerant transfer operation, the decompression devices 4, 7 a and 7 b are closed, and then an operation such as a cooling operation or a heating operation is started. As a result, liquid return on the suction side of the compressor 1 can be avoided regardless of the operation mode and the refrigerant state.
[0028]
FIG. 15 shows yet another embodiment of FIG. In FIG. 1, the pipe 13 i, the pipe 13 j, and the bypass passage 14 are connected via the three-way valve 11, but in the example of FIG. 15, three pipes are joined at the junction 72 and connected. Further, the discharge side of the compressor 1 is branched into two passages (pipe 13a, pipe 13q) and connected to the four-way valves 2a and 2b, respectively. The four-way valve 2a is connected to a pipe 13a, a pipe 13b, a pipe 13i, and a pipe 13h. The pipe 13a and the pipe 13b, the pipe 13i and the pipe 13h are connected during the cooling operation, and the pipe 13a and the pipe 13h during the heating operation. The pipe 13b and the pipe 13i are connected. Pipes 13q, 13r, 13o and 13p are connected to the four-way valve 2b. The pipes 13q and 13r and the pipes 13o and 13p are connected during cooling operation, and the pipes 13q and 13p and pipes 13r are connected during heating operation. And the pipe 13o are connected. The other end of the pipe 13p joins the pipe 13g at a junction 73. The other end of the pipe 13 o joins the pipe 13 h and the bypass passage 14 at a junction 72. The pipe 13 i joins the pipe 13 o at the junction 74. The pipe 13r joins the pipe 13b at the junction 75. A check valve 31b is provided on the pipe 13r, and the refrigerant flows only from the four-way valve 2b to the heat source side heat exchanger 3. Further, a check valve 31a is provided on the pipe 13i, and the refrigerant flows only from the four-way valve 2a to the pipe 13o.
In the refrigerant transfer operation, the four-way valve 2a is set to the cooling operation mode, and the four-way valve 2b is set to the heating operation mode. The decompression devices 4, 7a and 7b are fully open. When the compressor 1 is started in this state, each heat exchanger and the refrigerant in the pipe can be moved to the upstream side (the receiver 5 side) of the decompression device 4 and the decompression devices 7a and 7b. At the end of the refrigerant transfer operation, the decompression devices 4, 7a and 7b are closed, and thereafter operations such as cooling operation and heating operation are started. As a result, liquid return on the suction side of the compressor 1 can be avoided regardless of the operation mode and the refrigerant state.
[0029]
FIG. 16 shows the flow of the refrigerant when performing the cooling operation in the cycle shown in FIG. FIG. 17 shows the flow of the refrigerant when performing the heating operation in the cycle shown in FIG.
18 shows the connection position on the compressor side of the bypass passage 33 in FIG. 14 corresponding to the bypass passage 14 in FIG. 5 in the cycle shown in FIG. 5 instead of the suction side piping of the compressor. This is a cycle configuration in the middle of the compression process. In this cycle, the bypass passage 33 can be used to configure a gas injection cycle during the cooling operation and the heating operation.
FIG. 19 shows an example of a compressor used as the compressor 1 on the cycle shown in FIG. The bypass passage 33 is connected to a compression chamber 50 formed by a fixed scroll 44 and an end plate 45.
FIG. 20 shows an example of the structure of the liquid receiver. The liquid receiver 5 has a partition plate 64 at the bottom center, and a pipe 62a and a pipe 62b are inserted therein. The ends of the pipe 62a and the pipe 62b are positioned lower than the upper end of the partition plate 64 so as to prevent mutual interference between the refrigerant flows flowing out from the respective pipes. The liquid receiver 5 gas-liquid-separates the two-phase refrigerant into a gas phase in the upper layer and a liquid phase in the lower layer due to the gas-liquid density difference, that is, the influence of gravity.
The pipes 62a and 62b inserted in the liquid receiver 5 are used to make the dryness of the refrigerant flow flowing out of the liquid receiver 5 (the ratio of the mass flow rate of the gas refrigerant to the total refrigerant mass flow rate) moderate. There are gas vent holes 63a, 63b. Moreover, the end part of the bypass passage 61 connected to the suction side of the compressor is attached to the upper part of the liquid receiver 5 and takes out only the gas refrigerant.
In the above description, the refrigerant transfer operation is performed before the cooling operation, the heating operation or the defrosting operation, and after the restart of the compressor during the defrosting operation, but the refrigerant transfer operation may be performed immediately before the end of each operation. Good. This is the same as the refrigerant recovery operation for the liquid receiver.
[0030]
Especially for combustible refrigerants, the refrigerant can be collected in the outdoor unit by performing the refrigerant transfer operation immediately before the end of the operation, so that leakage of refrigerant into the room is prevented, and even if it leaks, the minimum leakage amount It is possible to hold it down. Two closed cycles each including an outdoor heat source side heat exchanger and an indoor use side heat exchanger can be configured at the same time, and it is preferable to perform a refrigerant transfer operation, but at least an indoor use side heat exchanger is included. It is desirable to configure a closed cycle and perform a refrigerant transfer operation.
In the above example, liquid return can be eliminated regardless of the type of refrigerant, the type of oil, the type of compressor such as a scroll compressor, reciprocating compressor, rotary compressor, etc., so HFC refrigerants represented by R407C and R410A in particular. In the case of natural refrigerants such as carbon dioxide and HC refrigerants, the amount of refrigerant used can be reduced, which is desirable for the preservation of the global environment. Furthermore, if it is a scroll compressor, efficiency can improve more and it can make it more desirable for global environment conservation.
It is also possible to use a constant speed, inverter-driven compressor, and in a low pressure chamber type compressor in which the motor part in the compressor is on the refrigerant suction side, or in the high pressure chamber in which the motor part in the compressor is on the refrigerant discharge side This is also effective for compressors of the type, so inverter-driven, high-pressure chamber type compressors can be operated efficiently with respect to the required load, further reducing the amount of power consumption, etc. Can be desirable.
[0031]
As described above, by changing the cycle with an accumulator to a cycle with a receiver, for example, in a cooling operation, the liquid refrigerant is stored in the receiver, the liquid refrigerant condensed in the heat source side heat exchanger of the outdoor unit is moved to the receiver, and the liquid refrigerant is Since the accumulated heat exchanger can be used in the two-phase region, the heat exchanger can be effectively used. As a result, the condensing pressure is reduced and the compression work is reduced, so that the power consumption can be reduced with the same cooling capacity.
For example, in the case of one outdoor unit and one indoor unit with a cooling capacity of 14 kW, the cooling COP (coefficient of performance = cooling capacity / power consumption) is improved by about 10% from about 2.6 to about 2.8 to 2.9. it can. The same effect can be obtained during heating operation.
Conventionally, in a cycle with a receiver, an accumulator must also be mounted in order to ensure the reliability of the compressor against liquid return. However, according to the present invention, it is possible to provide a cycle with a receiver without an accumulator. As a result, for example, in an outdoor unit having a cooling capacity of 14 kW, when both an accumulator and a receiver are mounted, the width of the outdoor unit is about 1.2 m. It is possible to reduce the size by about 10% to 1 m.
[0032]
Furthermore, for example, in the model of one outdoor unit and one indoor unit with a cooling capacity of 14 kW, by changing the cycle with an accumulator to a cycle with a receiver, the amount of liquid refrigerant accumulated in the heat exchanger acting as a condenser can be reduced. The amount of refrigerant enclosed can be reduced by about 20% from 5.6 kg to about 4.0 to 4.5 kg (reducing refrigerant), and when both an accumulator and a receiver are installed, the amount of refrigerant enclosed is about 4.5-5. According to the present invention, it is not necessary to arrange an accumulator to be 0 kg, so that the refrigerant filling amount can be about 4 to 4.5 kg, so that the effect of saving refrigerant can be maintained.
[0033]
The operation time of the refrigerant transfer operation in the closed cycle on the indoor unit side varies depending on the pipe length between the outdoor heat exchanger and the indoor heat exchanger and the number of indoor units. For example, when the length of the pipe between the outdoor heat exchanger and the indoor heat exchanger is 5 m with one outdoor unit and one indoor unit, the operation time is preferably about 0.5 to 1.5 minutes. If the pipe length is longer than that,
Operating time (min) = piping length (m) / 5 (m) x 0.5 to 1.5 (min)
If you have more than one indoor unit,
Operation time (minutes) = Number of indoor units (units) x 0.5 to 1.5 (minutes / unit)
It is desirable to drive for a long time.
Furthermore, the operation time of the refrigerant transfer operation in the closed cycle on the outdoor unit side is preferably about 0.5 to 1.5 minutes.
[Brief description of the drawings]
[0034]
FIG. 1 is a cycle diagram of an air conditioner provided with a receiver-compressor bypass passage according to an embodiment of the present invention.
FIG. 2 is a cycle diagram showing a cycle configuration and a refrigerant flow during a refrigerant transfer operation before a cooling operation in the air conditioner of FIG. 1;
3 is a cycle diagram showing a cycle configuration and a refrigerant flow during a refrigerant transfer operation before a heating operation in the air conditioner of FIG. 1; FIG.
4 is a cycle diagram showing a cycle in which a flow rate control valve is provided in the receiver-compressor bypass passage in the air conditioner of FIG. 1. FIG.
FIG. 5 is a cycle diagram showing a cycle in which an on-off valve is used instead of the three-way valve in the air conditioner of FIG. 1;
6 is a cycle diagram showing a refrigerant flow during a refrigerant transfer operation before a cooling operation in a cycle configuration using a six-way valve instead of the four-way valve and the three-way valve in the air conditioner of FIG. 1;
7 is a cycle diagram showing the refrigerant flow during the refrigerant transfer operation before the heating operation in the air conditioner of FIG. 6. FIG.
FIG. 8 is a cycle diagram showing a refrigerant flow during cooling operation in the air conditioner of FIG. 6;
FIG. 9 is a cycle diagram showing the refrigerant flow during heating operation in the air conditioner of FIG. 6;
FIG. 10 is a cycle diagram showing a cycle configuration and a refrigerant flow during simultaneous simultaneous refrigerant transfer operation before cooling operation using a three-mode four-way valve.
FIG. 11 is a diagram showing a structure and a refrigerant flow during cooling operation of a three-mode four-way valve.
FIG. 12 is a diagram showing the structure and refrigerant flow during heating operation of a three-mode four-way valve.
FIG. 13 is a view showing the structure and refrigerant flow during refrigerant transfer operation of a three-mode four-way valve.
FIG. 14 is a cycle diagram showing a cycle configuration that is another embodiment in which an on-off valve is used in place of the three-mode four-way valve in the air conditioner of FIG. 10 and the refrigerant flow during the refrigerant transfer operation.
FIG. 15 is a cycle diagram showing the cycle configuration and the refrigerant flow during the refrigerant transfer operation as another embodiment using two four-way valves instead of the three-mode four-way valve in the air conditioner of FIG. 10; .
FIG. 16 is a cycle diagram showing the refrigerant flow during cooling operation in the air conditioner of FIG. 14;
FIG. 17 is a cycle diagram showing the refrigerant flow during heating operation in the air conditioner of FIG. 14;
18 is a cycle diagram showing a cycle configuration when one end of a bypass passage on the cycle according to the embodiment of FIG. 1 is connected in the middle of the compression process of the compressor and a refrigerant flow during a refrigerant transfer operation. .
FIG. 19 is a cross-sectional view showing a compressor used in the cycle shown in FIG. 18;
FIG. 20 is a cross-sectional view showing a liquid receiver structure used in one embodiment.
[Explanation of symbols]
[0035]
DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Four way valve, 3 ... Heat source side heat exchanger, 4 ... Pressure reducing device, 5 ... Liquid receiving device, 7 ... Pressure reducing device, 8 ... Usage side heat exchanger, 11 ... Three-way valve, 14 ... Bypass aisle.

Claims

In an air conditioner having a refrigeration cycle in which a compressor, a four-way valve, a heat source side heat exchanger, an outdoor pressure reducing device, a receiver, an indoor pressure reducing device, and a use side heat exchanger are connected by piping,
A bypass passage connecting the suction side of the compressor and the liquid receiver;
A control valve that closes the bypass passage when the passage of the refrigeration cycle is open and opens the bypass passage when the passage is closed, and opens the bypass passage at least when starting the operation of the air conditioner. And then operating the compressor for a predetermined time.

In an air conditioner having a refrigeration cycle in which a compressor, a four-way valve, a heat source side heat exchanger, an outdoor pressure reducing device, a receiver, an indoor pressure reducing device, and a use side heat exchanger are connected by piping,
A bypass passage connecting the suction side of the compressor and the liquid receiver;
A three-way valve provided at the junction of the bypass passage and the suction side of the compressor;
The bypass passage and the suction side of the compressor are communicated with each other by the three-way valve , and include either the compressor, the heat source side heat exchanger or the utilization side heat exchanger, and the bypass passage. forming a closed cycle, the air conditioner, wherein the compressor to be operated a predetermined time after forming the closed cycle.

In an air conditioner having a refrigeration cycle in which a compressor, a four-way valve, a heat source side heat exchanger, an outdoor pressure reducing device, a receiver, an indoor pressure reducing device, and a use side heat exchanger are connected by piping,
A bypass passage connecting the suction side of the compressor and the liquid receiver;
Opening the outdoor pressure reducing device and the indoor pressure reducing device,
A first closed cycle including one of the compressor, the heat source side heat exchanger, and the use side heat exchanger on the suction side of the compressor, the liquid receiver, and the bypass passage; ,
A second closed cycle including the other heat exchanger on the discharge side of the compressor among the compressor, the heat source side heat exchanger, and the use side heat exchanger, the liquid receiver, and the bypass passage; After forming the above, the compressor is operated for a predetermined time.

In an air conditioner including a compressor, a four-way valve, a heat source side heat exchanger, an outdoor unit having an outdoor pressure reducing device and a liquid receiver, an indoor pressure reducing device, and a plurality of indoor units having a use side heat exchanger,
A bypass passage connecting the suction side of the compressor and the liquid receiver; and at least 0.5 to 1.5 minutes after opening the bypass passage at the start of operation of the air conditioner The air conditioner is operated for a time multiplied by the number of the plurality of indoor units.

The air conditioner according to claim 1, wherein a three-way valve is provided at a junction between the bypass passage and the suction side of the compressor.

2. The air conditioner according to claim 1, wherein the bypass passage is connected to a position that is an upper portion of the liquid receiver.

The air conditioner according to claim 1, wherein a flow rate control valve is provided in the bypass passage.

In an outdoor unit having a compressor, a four-way valve, a heat source side heat exchanger, an outdoor pressure reducing device, and a liquid receiver,
A bypass passage that connects the suction side of the compressor and the liquid receiver; and a control valve that opens and closes the bypass passage. After the bypass passage is opened before the start of cooling and heating operation , the compressor Is operated for a predetermined time.

9. The outdoor unit according to claim 8, wherein a three-way valve is provided at a junction between the bypass passage and the suction side of the compressor.

The air conditioner according to claim 3, wherein the refrigerant flowing through the refrigeration cycle is a natural refrigerant.