JP3849467B2

JP3849467B2 - Air conditioner

Info

Publication number: JP3849467B2
Application number: JP2001210454A
Authority: JP
Inventors: 宜正石川
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2001-07-11
Filing date: 2001-07-11
Publication date: 2006-11-22
Anticipated expiration: 2021-07-11
Also published as: JP2003028517A

Description

【０００１】
【発明の属する技術分野】
本発明は、室内機と室外機を接続配管で接続した、分離型の空気調和機の制御に関する。
【０００２】
【従来の技術】
従来分離型の空気調和機において電動膨張弁によって冷凍サイクルの冷媒循環量を制御する方法としては、例えば特許第２９２１２５４号公報を挙げることができる。
【０００３】
この従来例においては、蒸発温度と凝縮温度と圧縮機単体の傾斜特性線により、モリエル線図上から目標吐出温度を設定し、圧縮機の吐出温度が目標吐出温度になるよう電動膨張弁によって冷媒循環量を制御することで、冷媒の過熱度を制御している。
【０００４】
また特開平１２−２９２０１３号公報においては、蒸発温度や圧縮機への吸入冷媒温度によって目標吐出温度を補正することで、冷媒の過熱度の上昇を抑え、蒸発器の乾きすぎを防止するといった技術も公開されている。
【０００５】
【発明が解決しようとする課題】
ところで、近年省エネルギや快適性といった観点から、圧縮機の回転数が大きく変化するインバータを搭載した分離型の空気調和機が多く普及している。また設置自由度の拡大という観点から接続可能な配管長に関しても、より短く、より長くまで接続できるよう要求されている。
【０００６】
しかしながらこのような空気調和機においては、インバータ制御により冷媒循環量が大きく変化し、更に室内機の設置位置のニーズの多様化により接続配管長も大きく変化するため、図６に示す冷媒循環量と配管長の圧損関係のように、冷房運転時に蒸発器の圧力と圧縮機の吸入側圧力との圧力差（「圧力差」を以後「圧損」と称す）も大きく変化する。
【０００７】
その結果図７に示すモリエル線図のように、蒸発温度と凝縮温度だけで目標吐出温度を設定しても接続配管の圧損影響で圧縮機の吸入点は図中のＢ点やＣ点のように変動し、吸入側の冷媒過熱度を適正過熱度に保つことが困難であった。
【０００８】
一般に圧縮機の吸入側の冷媒過熱度が適正過熱度（冷媒の種類、冷房／暖房などの運転モード、運転周波数、などに依存して変わり得る）に保たれていれば、圧縮機の運転効率が高くなり省エネ運転が可能となる。
【０００９】
そこで冷媒過熱度が大きくなりすぎると、蒸発器において過熱度が取れる部分が多くなり除湿されない空気が送風機で冷気と混合されて室内機から結露水が飛散するといった問題が生じやすくなる。一方吸入冷媒が湿り過ぎる（冷媒過熱度が全くとれていない）と、液バックといった圧縮機の信頼性低下問題が生じやすくなる。
【００１０】
また室内機の蒸発温度と圧縮機の吸入温度で目標吐出温度を補正し、冷媒の過熱度を抑制しようとしても、運転条件（例えば圧縮機回転数）の変化により接続配管での圧損が変われば、十分な抑制を行うことができない。更に施工条件（配管長）が変わると圧損変化により冷媒の過熱度も変わる。
【００１１】
そこで、スイッチ等で施工者が確実に実配管長を設定する必要があり、製品コストが上がる、施工時間が長くなるといった課題が生じる。
【００１２】
そこで本発明は、斯かる点に鑑みてなされたものであり、その目的は、冷房運転時に様々な運転条件下や施工条件下でも圧縮機の吸入冷媒圧力を高精度で推定することにより吸入側の冷媒過熱度を適正過熱度に制御し、運転効率を高め、室内機の結露を防止するとともに圧縮機の信頼性を高めることができる安価な空気調和機を提供するものである。
【００１３】
【課題を解決するための手段】
上記課題を解決するために、請求項１に記載の空気調和機は、容量可変形圧縮機と室外熱交換器と弁開度を制御可能な電動膨張弁とを有する室外機と、室内熱交換器と前記室内熱交換器の温度を検出する第１の温度検出手段とを有する室内機と、前記室外機と前記室内機を接続する接続配管を有する空気調和機において、前記接続配管の配管長を予め記憶する記憶手段と、冷房運転時に前記第１の温度検出手段により検出された蒸発温度と前記記憶手段に記憶されている配管長と前記圧縮機の回転数とに基づいて、前記圧縮機の吸入冷媒圧力を推定する第１の推定手段と、室外熱交換器の温度を検出する第２の温度検出手段と、圧縮機の吐出温度を検出する第３の温度検出手段と、前記第２の温度検出手段により検出された凝縮温度と前記第１の推定手段により推定された吸入冷媒圧力に基づいて圧縮機の目標吐出温度を算出する目標吐出温度算出手段と、前記電動膨張弁の開度を制御することにより、前記目標吐出温度を目指して、前記第３の温度検出手段により検出される吐出温度を変更させる膨張弁制御手段とを備えたものである。
【００１４】
このように、蒸発器圧力に圧損を考慮することで運転条件が変化しても圧縮機への吸入冷媒圧力を高精度に推定することができ、その高精度に推定された吸入冷媒圧力を使って目標吐出温度を算出し吐出温度を制御するため、運転条件が変化しても高精度に実際の吸入冷媒過熱度を適正過熱度に制御することができる。
【００１５】
【発明の実施の形態】
上記課題を解決するために、請求項１に記載の本発明は、容量可変形圧縮機と室外熱交換器と弁開度を制御可能な電動膨張弁とを有する室外機と、室内熱交換器と前記室内熱交換器の温度を検出する第１の温度検出手段とを有する室内機と、前記室外機と前記室内機を接続する接続配管を有する空気調和機において、前記接続配管の配管長を予め記憶する記憶手段と、冷房運転時に前記第１の温度検出手段により検出された蒸発温度と前記記憶手段に記憶されている配管長と前記圧縮機の回転数とに基づいて、前記圧縮機の吸入冷媒圧力を推定する第１の推定手段と、室外熱交換器の温度を検出する第２の温度検出手段と、圧縮機の吐出温度を検出する第３の温度検出手段と、前記第２の温度検出手段により検出された凝縮温度と前記第１の推定手段により推定された吸入冷媒圧力に基づいて圧縮機の目標吐出温度を算出する目標吐出温度算出手段と、前記電動膨張弁の開度を制御することにより、前記目標吐出温度を目指して、前記第３の温度検出手段により検出される吐出温度を変更させる膨張弁制御手段とを備えたものである。
【００１６】
このように、蒸発器圧力に圧損を考慮することで運転条件が変化しても圧縮機への吸入冷媒圧力を高精度に推定することができ、その高精度に推定された吸入冷媒圧力を使って目標吐出温度を算出し吐出温度を制御するため、運転条件が変化しても高精度に実際の吸入冷媒過熱度を適正過熱度に制御することができる。
【００１７】
また、請求項２記載の本発明は、容量可変形圧縮機と室外熱交換器と弁開度を制御可能な複数の電動膨張弁とを有する室外機と、室内熱交換器と前記室内熱交換器の温度を検出する第１の温度検出手段とを有する複数の室内機とを接続配管により並列に接続したマルチタイプの空気調和機において、前記各室内機への各接続配管の配管長を予め記憶する記憶手段と、冷房運転時に前記各室内機の前記第１の温度検出手段により検出された各蒸発温度と前記記憶手段に記憶されている各接続配管の配管長と前記圧縮機の回転数とに基づいて、前記圧縮機の吸入冷媒圧力を推定する第１の推定手段と、室外熱交換器の温度を検出する第２の温度検出手段と、圧縮機の吐出温度を検出する第３の温度検出手段と、前記第２の温度検出手段により検出された凝縮温度と前記第１の推定手段により推定された吸入冷媒圧力に基づいて圧縮機の目標吐出温度を算出する目標吐出温度算出手段と、前記電動膨張弁の開度を制御することにより、前記目標吐出温度を目指して、前記第３の温度検出手段により検出される吐出温度を変更させる膨張弁制御手段とを備えたものである。
【００１８】
このように、マルチタイプの空気調和機においても、蒸発器圧力に圧損を考慮することで運転条件が変化しても圧縮機への吸入冷媒圧力を高精度に推定することができ、高精度に推定された吸入冷媒圧力を使って目標吐出温度を算出し吐出温度を制御するため、運転条件が変化しても高精度に実際の吸入冷媒過熱度を適正過熱度に制御することができる。
【００１９】
また請求項３記載の本発明は、圧縮機の吸入温度を検出する第４の温度検出手段と、前記第４の温度検出手段により検出された吸入温度と第１の推定手段で推定された吸入冷媒圧力とから飽和温度を求めるとともに、その飽和温度に基づき前記圧縮機の吸入冷媒過熱度を推定する第２の推定手段と、第３の温度検出手段により検出された吐出温度が目標吐出温度算出手段により算出された目標吐出温度に対し所定範囲内にあり、かつ前記第２の推定手段により推定された圧縮機の吸入冷媒過熱度が所定範囲から外れた場合に、予め記憶手段に記憶されている配管長を修正する配管長修正手段を備えたものである。
【００２０】
このように、予め記憶されている配管長が実際に据付られている配管長と大きく異なる場合でも自動的に配管長を修正するため、修正を行う度に実際の配管長に近づくことになる。この結果、推定された吸入冷媒圧力が修正され、これに伴い目標吐出温度も修正されるため、運転条件や施工条件が変化しても実際の吸入冷媒過熱度は適正過熱度近傍へと修正される。
【００２１】
また請求項４記載の本発明は、室内熱交換器のガス側配管のガス温度を検出する第５の温度検出手段と、前記第５の温度検出手段により検出されたガス温度と第１の温度検出手段により検出された蒸発温度に基づき室内冷媒過熱度を検出する室内冷媒過熱度検出手段と、第３の温度検出手段により検出された吐出温度が目標吐出温度算出手段により算出された目標吐出温度に対し所定範囲内にあり、かつ前記室内冷媒過熱度検出手段により検出された室内冷媒過熱度が所定範囲から外れた場合に予め記憶手段に記憶されている配管長を修正する配管長修正手段を備えたものである。
【００２２】
このように、予め記憶されている配管長が実際に据付られている配管長と大きく異る場合でも自動的に配管長を修正するため、修正を行う度に実際の配管長に近づくことになる。この結果目標吐出温度が修正され、室内冷媒過熱度も修正されるため、運転条件や施工条件が変化しても実際の吸入冷媒過熱度は適正過熱度近傍へと修正される。
【００２３】
また請求項５記載の本発明は、第２の推定手段により推定された圧縮機の吸入冷媒過熱度が所定値となるよう電動膨張弁の開度を制御する膨張弁制御手段を備えたものである。
【００２４】
このように高精度に推定された吸入冷媒圧力を使って吸入冷媒過熱度を制御するため、運転条件が変化しても高精度に実際の吸入冷媒過熱度を適正過熱度に制御することができる。
【００２５】
また請求項６記載の本発明は、第２の推定手段により推定された圧縮機の吸入冷媒過熱度が所定範囲内にあり、かつ第３の温度検出手段により検出された吐出温度が目標吐出温度算出手段により算出された目標吐出温度に対し所定範囲から外れた場合に、予め記憶手段に記憶されている配管長を修正する配管長修正手段を備えたものである。
【００２６】
このように、予め記憶されている配管長が実際に据付られている配管長と大きく異なる場合でも自動的に配管長を修正するため、修正を行う度に実際の配管長に近づくことになる。この結果、推定された吸入冷媒圧力が修正され、これに伴い運転条件や施工条件が変化しても実際の吸入冷媒過熱度は適正過熱度近傍へと修正される。
【００２７】
また請求項７記載の本発明は、配管長修正手段により修正された配管長が所定配管長から外れた場合、据付配管長が適切ではない旨を使用者に知らせる異常検出手段を備えたものである。
【００２８】
このように、実際に据付られている配管長が適正配管長から逸脱され、システムの運転に不具合が生じやすい場合に使用者にその旨を知らせることができ、この結果システムの重大な損傷等を間逃れることができる。
【００２９】
以下、本発明の実施の形態について、図面を参照しながら説明する。
（実施の形態１）
図１は、本発明の実施形態の構成を示す構成図であり、室外機１と室内機２が接続配管８により接続され、冷凍サイクルを形成している。
【００３０】
図１において、室外機１にはインバータ駆動の容量可変形圧縮機３（以下単に圧縮機と称す）と室外熱交換器５と冷暖房切換用の四方弁４とが設けられる一方、室内機２には室内熱交換器７が設けられている。また、室外機１の液側主管には、例えばステッピングモータ等により弁開度を制御可能な電動膨張弁６が介装されている。
【００３１】
上記構成の冷凍サイクルにおいて、冷房時、圧縮機３から吐出された冷媒は、四方弁４より室外熱交換器５へと流れて、ここで室外空気と熱交換して凝縮液化し、次に電動膨張弁６を通過することにより減圧されて冷媒は蒸発しやすい状態となり、接続配管８の液側配管を通って室内熱交換器７へと流れて室内空気と熱交換して蒸発した後、接続配管８のガス側配管を通って再び圧縮機３に吸入される。また、圧縮機３の回転数は、室内機２からの要求能力に応じて決定される（本発明と直接関係しないため、説明は省略する）。
【００３２】
次に、圧縮機３への吸入冷媒圧力を推定する方法について説明する。
【００３３】
まず第１の推定手段（マイクロコンピュータ）は室内熱交換器温度センサ１１により得られた蒸発温度Ｔｅを用いて飽和圧力変換に基づいて蒸発器圧力Ｐｅを求め、前記蒸発器圧力Ｐｅから圧損△Ｐを減ずることにより吸込冷媒圧力Ｐｓを推定する。
【００３４】
ここで冷凍サイクル内を流れる冷媒循環量は圧縮機３の回転数Ｒにほぼ比例することから、式（２）に示す圧縮機３の回転数Ｒと記憶手段（メモリ装置）に記憶されている接続配管８の長さＨ（例えば１０ｍ）から圧損△Ｐを推定する。
Ｐｓ＝Ｐｅ−△Ｐ・・・・・式（１）
△Ｐ＝ａ×Ｒ² ×Ｈ・・・式（２）（ａ、ｂは定数）
このように、圧損を高精度で推定することで、吸入冷媒圧力も高精度で推定できる。ここで圧損△Ｐの推定時に回転数Ｒと配管長Ｈを用いたが、更に精度を高めるため蒸発温度Ｔｅや凝縮温度Ｔｃを加えてもよい。
（実施の形態２）
また図２は本発明のマルチタイプの空気調和機の一実施形態の構成を示す系統図である。マルチタイプの場合、第１の推定手段（マイクロコンピュータ）は記憶手段に記憶されている各配管長Ｈａ、Ｈｂ（２室マルチの場合なのでａ，ｂを添字につけた。以下、Ｔｅなどについても同様）から平均配管長Ｈｒ［＝（Ｈａ＋Ｈｂ）／２］を算出し、圧縮機３の平均回転数Ｒｒ（＝Ｒ／２）を算出するとともに、前記平均配管長Ｈｒと前記平均回転数Ｒｒから式（２）より平均圧損△Ｐｒを算出する。
【００３５】
そして各室内機２ａ，２ｂの夫々の蒸発温度Ｔｅａ、Ｔｅｂから平均蒸発温度Ｔｅｒ［＝（Ｔｅａ＋Ｔｅｂ）／２）］を算出し、前記平均蒸発温度Ｔｅｒからの圧力変換により平均蒸発器圧力Ｐｒを求め、前記平均蒸発器圧力Ｐｒと前記平均圧損△Ｐｒから式（１）より吸込冷媒圧力Ｐｓを推定する。このようにマルチタイプの空気調和機においては、平均配管長を用いて平均圧損を推定するため、全体圧損を高精度に推定でき、その結果吸入冷媒圧力も高精度で推定できる。
【００３６】
次に吸入冷媒過熱度を間接的に制御する吐出温度制御について説明する。まず圧縮機３の圧縮原理はポリトロープ圧縮であることから、ポリトロープ圧縮の理論関係式を用いて適正過熱度ＳＨｍでの吐出温度が計算できる。そこで目標吐出温度算出手段（マイクロコンピュータ）は室外熱交換器温度センサ１０により検出された凝縮温度Ｔｃからの圧力変換に基づき圧縮機３の吐出冷媒圧力Ｐｄ（Ｔｃの関数）を算出する。
【００３７】
そして前記吐出冷媒圧力Ｐｄと、第１の推定手段により推定された圧縮機への吸入冷媒圧力Ｐｓと、前記吸入冷媒圧力Ｐｓでの飽和温度変換Ｔｗｓ（Ｐｓの関数）と、適正過熱度ＳＨｍから式（３）の理論関係式を用いて圧縮機３の目標吐出温度Ｔｄｍを算出する。
Ｔｄｍ＝（Ｐｄ／Ｐｓ）^(p-1/p)×（Ｔｗｓ＋ＳＨｍ＋ｂ）−ｃ・・・・式
（３）ここでｐは実験で求められるポリトロープ指数、ｂ、ｃは定数、である。
【００３８】
更に膨張弁制御手段１（マイクロコンピュータ）は、吐出温度センサ９により検出された吐出温度Ｔｄと前記目標吐出温度Ｔｄｍとの温度差△Ｔに基づいて、電動膨張弁６の操作開度△Ｋを算出し、所定時間ごとに（例えば６０秒毎に）電動膨張弁６を制御する。
△Ｔ＝Ｔｄ−Ｔｄｍ・・・式（４）
△Ｋ＝ｄ×△Ｔ・・・式（５）（ｄは定数である）
このように、高精度に推定された吸入冷媒圧力を使って目標吐出温度を算出し、フィードバック制御を行うため、運転条件が変化しても高精度に実際の吸入冷媒過熱度を適正過熱度ＳＨｍに制御することができる。
【００３９】
上記説明では吐出冷媒圧力Ｐｄの算出時に凝縮温度Ｔｃを用いて圧力変換を行ったが、更に精度を高めるため、式（３）において圧縮機３の回転数Ｒの項をつけを加えて算出してもよい。
【００４０】
また電動膨張弁６の操作開度△Ｋの算出方法に温度差△Ｔを用いたが、ここにＰＩＤ制御やファジー制御といった制御方法を用いても同様の効果が得られる。
【００４１】
次に実際に据付られている実配管長と記憶手段に記憶されている配管長が大きく異なる場合の冷凍サイクル挙動について説明する。
【００４２】
図７は上記吐出温度制御を行った場合のモリエル線図を示している。
【００４３】
図７において太線で書かれたサイクルは実際に据付られている実配管長と記憶手段に記憶されている配管長が等しい時の冷凍サイクルを示している。ここから実配管長Ｈｔが配管長Ｈよりも短くなると、実際の吸入圧力は推定された吸入圧力Ａ点よりも高いＢ点となり、実際の吸入冷媒過熱度は適正過熱度ＳＨｍよりも大きくなる。
【００４４】
この結果、運転効率が低下したり室内機から結露水が飛散するといった問題が生じやすくなる。逆に実配管長Ｈｔが配管長Ｈよりも長くなると、実際の吸入圧力は推定された吸入圧力Ａ点よりも低いＣ点となり、実際の吸入冷媒過熱度は適正過熱度ＳＨｍよりも小さくなる。この結果、運転効率が低下したり液バックといった圧縮機の信頼性低下問題が生じやすくなる。
【００４５】
そこで、実際に据付られている実配管長Ｈｔと記憶手段に記憶されている配管長Ｈが大きく異なる場合の吐出温度制御について図３の吐出温度制御の一例を示すフローチャートを用いて説明する。
【００４６】
まずステップＳ１では配管長Ｈを初期値１０ｍに設定するとともに、カウンタＭとＮを０にセットする。ステップＳ２では制御間隔（６０秒）をカウントするタイマをリセットし、ステップＳ３でタイマをスタートさせる。
【００４７】
ステップＳ４では蒸発温度Ｔｅと凝縮温度Ｔｃと吐出温度Ｔｄと圧縮機回転数Ｒと吸入温度センサ１２により吸入温度Ｔｓを読み込む。ステップＳ５では推定手段１または２により吸入冷媒圧力Ｐｓを推定し、ステップＳ６では目標吐出温度算出手段により目標吐出温度Ｔｄｍを算出し、スッテプＳ７では第２の推定手段により式（６）を用いて吸入冷媒過熱度ＳＨｓを推定する。
ＳＨｓ＝Ｔｓ−Ｔｗｓ・・・式（６）
ステップＳ８では配管長修正手段１により吐出温度Ｔｄが目標吐出温度Ｔｄｍに対し±ｇ℃以内（例えば０．５℃以内）に入っているか判断し、Ｔｄｍ±ｇ℃に入っていれば、ステップＳ９に進む。
【００４８】
一方ステップＳ８にて吐出温度ＴｄがＴｄｍ±ｇ℃以内に入っていなければ、ステップＳ２７、Ｓ１６、Ｓ１７、Ｓ１８と進み、吐出温度Ｔｄが目標吐出温度Ｔｄｍになるよう膨張弁制御手段１により膨張弁６の開度操作を行う。ステップＳ１９ではタイマが６０秒経過するのを待ってから、再びステップＳ２に戻りフィードバック制御を行う。
【００４９】
またステップＳ９においては、吸入冷媒過熱度ＳＨｓが適正過熱度ＳＨｍ＋ｈ（例えば３Ｋ）を超えているか判断し、超えている場合は実配管長Ｈｔが配管長Ｈよりも短いとみなし、ステップＳ１０にて短いと判断された回数をカウントするカウンタＭをプラス１するのと同時に長いと判断された回数をカウントするカウンタＮを０にセットする。
【００５０】
ステップＳ１１ではカウンタＭがα以上かを判断し、カウンタＭがα以上であればα回（例えば１０回）連続で吸入冷媒過熱度ＳＨｓが適正過熱度ＳＨｍ＋ｈを超えているため、本当に実配管長Ｈｔが配管長Ｈよりも短いと判断し、ステップＳ１２にて配管長Ｈをｉ［ｍ］（例えば５［ｍ］）だけ短く修正する。
【００５１】
ここで吐出温度Ｔｄは圧縮機３の熱容量の影響で、蒸発温度Ｔｅや凝縮温度Ｔｃが安定していてもすぐには安定しないため、α回連続でという条件を入れることで、冷凍サイクルが不安定な時の誤判定を防止することができる。
【００５２】
ステップＳ１３、Ｓ１４では修正された配管長Ｈを用いて吸込冷媒圧力Ｐｓおよび目標吐出温度Ｔｄｍを再計算し修正する。ステップＳ１５ではカウンタＭをリセットした後、ステップＳ１６、Ｓ１７、Ｓ１８へと進み、吐出温度Ｔｄが修正された目標吐出温度Ｔｄｍになるよう膨張弁６の開度操作を行う。
【００５３】
またステップＳ９にて吸入冷媒過熱度ＳＨｓが適正過熱度ＳＨｍ＋ｈを超えていない場合は、ステップＳ２０にて吸入冷媒過熱度ＳＨｓが適正過熱度ＳＨｍ−ｈを下回っているか判断し、下回っている場合は実配管長Ｈｔが配管長Ｈよりも長いとみなし、同様にα回連続したらステップＳ２３、Ｓ２４、Ｓ２５、Ｓ２６にて配管長Ｈと吸込冷媒圧力Ｐｓおよび目標吐出温度Ｔｄｍを修正し、カウンタＮを０にセットする。
【００５４】
一方ステップＳ２０にて吸入冷媒過熱度ＳＨｓが適正過熱度ＳＨｍ−ｈ以上であれば実配管長Ｈｔは配管長Ｈにほぼ近いとみなし、配管長Ｈは修正せずに制御を行う。
【００５５】
上記のように配管長Ｈの修正を繰り返すことにより配管長Ｈは実配管長Ｈｔへと次第に近づいていく。その結果、図７に示す圧縮機３の吸入点は、Ｂ点またはＣ点からＢａ点またはＣａ点へと近づいていき、施工条件が変化しても実際の吸入冷媒過熱度を適正過熱度ＳＨｍ近傍へと修正することができる。
【００５６】
また前記実施の形態においては吐出温度Ｔｄが目標吐出温度Ｔｄｍに対し±ｇ［℃］以内にある場合、吸入冷媒過熱度ＳＨｓを用いて配管長Ｈの修正を判断したが、室内機２にて検出された冷媒過熱度を用いても同様の効果が得られる。
【００５７】
この場合は室内熱交換器７のガス側配管に設けられた室内ガス温度センサ１３により検出された冷媒ガス温度Ｔｇと蒸発温度Ｔｅから式（７）を用いて室内冷媒過熱度ＳＨｉを算出する。
ＳＨｉ＝Ｔｇ−Ｔｅ・・・式（７）
そして配管長修正手段２は吸入冷媒過熱度ＳＨｓの変わりに、室内冷媒過熱度ＳＨｉの値を用いて配管長Ｈの修正を判断する。なおフローチャートは図３とほぼ同じため、省略する。
【００５８】
またマルチタイプの空気調和機の場合、ステップＳ１２またはＳ２３にて修正される各配管長はｉ／２となる｛Ｈｒ＝Ｈｒ±ｉ＝［（Ｈａ±ｉ／２）＋（Ｈｂ±ｉ／２）］／２｝。またマルチタイプの空気調和機の場合は、全体冷媒循環量の制御と同時に各室内機への個別冷媒循環量も制御する必要がある。
【００５９】
そこで、ステップＳ１７にて各運転機の電動膨張弁６の操作開度△Ｋ（全運転機同じ）を算出した後、前記操作開度△Ｋを付加した全電動膨張弁６の合計開度［Σ（現在開度＋△Ｋ）］を算出し、前記合計開度を保ちながら各室内冷媒過熱度ＳＨｉｎ（ｎ＝ａ号機またはｂ号機）が同じ値になるよう各電動膨張弁６の開度を新開度に補正し（ａ号機の新開度＋ｂ号機の新開度＝合計開度）、ステップＳ１８にて各電動膨張弁６の開度を新開度に操作することで、全体冷媒循環量の制御と各室内機への個別冷媒循環量の制御を同時に行うことができる。この点については種々の制御が提案されて公知であるのでフローチャートからは省略する。
【００６０】
また上述したように吸入冷媒圧力が高精度に推定できるため、吸入冷媒過熱度を直接制御する吸入過熱度制御も可能になる。図４は推定手段３により推定された吸入冷媒過熱度ＳＨｓが適正過熱度ＳＨｍになるように吸入過熱度制御を行った場合のモリエル線図を示している。
【００６１】
図４において太線で書かれたサイクルは実際に据付られている実配管長と記憶手段に記憶されている配管長が等しい時の冷凍サイクルを示している。
【００６２】
ここから実配管長Ｈｔが配管長Ｈよりも短くなると、実際の吸入圧力は推定された吸入圧力Ａ点よりも高いＤ点となり、実際の吸入冷媒過熱度は適正過熱度ＳＨｍよりも小さくなる。この結果、運転効率が低下したり液バックといった圧縮機の信頼性低下問題が生じやすくなる。
【００６３】
逆に実配管長Ｈｔが配管長Ｈよりも長くなると、実際の吸入圧力は推定された吸入圧力Ａ点よりも低いＥ点となり、実際の吸入冷媒過熱度は適正過熱度ＳＨｍよりも大きくなる。この結果、運転効率が低下するといった問題が生じやすくなる。
【００６４】
そこで、実際に据付られている実配管長Ｈｔと記憶手段に記憶されている配管長Ｈが大きく異なる場合の吸入過熱度制御について図５の吸入過熱度制御の一例を示すフローチャートを用いて説明する。ステップＳ１からＳ７については図３のフローチャートと同じため省略する。
【００６５】
ステップＳ３０では配管長修正手段３により吸入冷媒過熱度ＳＨｓが適正過熱度ＳＨｍに対し±ｊ以内（例えば０．５Ｋ以内）に入っているか判断され、ＳＨｍ±ｊに入っていれば、ステップＳ３１に進む。一方ステップＳ３０にて吸入冷媒過熱度ＳＨｓがＳＨｍ±ｊ以内に入っていなければ、ステップＳ２７、Ｓ３３、Ｓ３４、Ｓ１８と進み、吸入冷媒過熱度ＳＨｓが適正過熱度ＳＨｍになるよう膨張弁制御手段２により膨張弁６の開度操作を行う。ステップＳ１９ではタイマが６０秒経過するのを待ってから、再びステップＳ２に戻りフィードバック制御を行う。
【００６６】
またステップＳ３１においては、吐出温度Ｔｄが目標吐出温度Ｔｄｍ−ｋ［℃］（例えば３［℃］）よりも低いか判断し、低い場合は実配管長Ｈｔが配管長Ｈよりも短いとみなし、ステップＳ１０にて短いと判断された回数をカウントするカウンタＭをプラス１するのと同時に、長いと判断された回数をカウントするカウンタＮを０にセットする。
【００６７】
ステップＳ１１ではカウンタＭがα以上かを判断し、カウンタＭがα以上であればα回（例えば１０回）連続で吸入冷媒過熱度ＳＨｓが適正過熱度ＳＨｍ＋ｈを超えているため、本当に実配管長Ｈｔが配管長Ｈよりも短いと判断し、ステップＳ１２にて配管長Ｈをｉｍ（例えば５ｍ）短く修正する。ステップＳ１３、Ｓ３２では修正された配管長Ｈを用いて吸込冷媒圧力Ｐｓおよび吸入冷媒過熱度ＳＨｓを再計算し修正する。
【００６８】
Ｓ１５ではカウンタＭをリセットした後、ステップＳ３３、Ｓ３４、Ｓ１８へと進み、修正された吸入冷媒過熱度ＳＨｓが適正過熱度ＳＨｍになるよう膨張弁６の開度操作を行う。
【００６９】
またステップＳ３１にて吐出温度Ｔｄが目標吐出温度Ｔｄｍ−ｋよりも低くない場合は、ステップＳ３５にて吐出温度Ｔｄが目標吐出温度Ｔｄｍ＋ｋよりも高いか判断し、高い場合は実配管長Ｈｔが配管長Ｈよりも長いとみなし、同様にα回連続したらステップＳ２３、Ｓ２４、Ｓ３６、Ｓ２６にて配管長Ｈと吸込冷媒圧力Ｐｓおよび吸入冷媒過熱度ＳＨｓを修正し、カウンタＮを０にセットする。
【００７０】
一方ステップＳ３５にて吐出温度Ｔｄが目標吐出温度Ｔｄｍ＋ｋ以下であれば実配管長Ｈｔは配管長Ｈにほぼ近いとみなし、配管長Ｈは修正せずに制御を行う。
【００７１】
上記のように配管長Ｈの修正を繰り返すことにより配管長Ｈは実配管長Ｈｔへと次第に近づいていく。その結果、図４に示す圧縮機３の吸入点はＤ点またはＥ点からＤａ点またはＥａ点へと近づいていき、施工条件が変化しても実際の吸入冷媒過熱度を適正過熱度ＳＨｍ近傍へと修正することができる。
【００７２】
また実際に据付られる配管長には、圧縮機３のオイルと冷媒の比率やオイルの戻り具合といった圧縮機の信頼性等を加味し最小配管長Ｈｍｉｎおよび最大配管長Ｈｍａｘが規定される。
【００７３】
一方上述したように配管長修正手段１または２または３により実配管長Ｈｔが推測できる。そこで異常検出手段（マイクロコンピュータ）は、配管長修正手段１または２または３により修正された配管長Ｈが、前記最小配管長Ｈｍｉｎから最大配管長Ｈｍａｘまでの適正配管長内であるか判断し、前記適正配管長内から外れた場合に室内機２に設けられているＬＥＤランプ２０（図示せず）を用いて据付配管長が適切ではない旨を表示する。これにより据付配管長が適切ではない旨を施工者や使用者に知らせることができ、配管施工の修正を促すことができる。
【００７４】
ここで前記ＬＥＤランプ２０の他にブザーによる音やリモコン等に表示しても、据付配管長が適切ではない旨を知らせることができる。このように、実際に据付られている配管長が適正配管長から逸脱され、システムの運転に不具合が生じやすい場合に、配管施工の修正を促すことでシステムの重大な損傷等を間逃れることができる。
【００７５】
【発明の効果】
本発明は、以上説明したように構成されているので、以下に記載されるような効果を奏する。
【００７６】
請求項１に記載の本発明は、容量可変形圧縮機と室外熱交換器と弁開度を制御可能な電動膨張弁とを有する室外機と、室内熱交換器と前記室内熱交換器の温度を検出する第１の温度検出手段とを有する室内機と、前記室外機と前記室内機を接続する接続配管を有する空気調和機において、前記接続配管の配管長を予め記憶する記憶手段と、冷房運転時に前記第１の温度検出手段により検出された蒸発温度と前記記憶手段に記憶されている配管長と前記圧縮機の回転数とに基づいて、前記圧縮機の吸入冷媒圧力を推定する第１の推定手段と、室外熱交換器の温度を検出する第２の温度検出手段と、圧縮機の吐出温度を検出する第３の温度検出手段と、前記第２の温度検出手段により検出された凝縮温度と前記第１の推定手段により推定された吸入冷媒圧力に基づいて圧縮機の目標吐出温度を算出する目標吐出温度算出手段と、前記電動膨張弁の開度を制御することにより、前記目標吐出温度を目指して、前記第３の温度検出手段により検出される吐出温度を変更させる膨張弁制御手段とを備えたものである。
【００７７】
このように、蒸発器圧力に圧損を考慮することで運転条件が変化しても圧縮機への吸入冷媒圧力を高精度に推定することができ、その高精度に推定された吸入冷媒圧力を使って目標吐出温度を算出し吐出温度を制御するため、運転条件が変化しても高精度に実際の吸入冷媒過熱度を適正過熱度に制御することができる。
【００７８】
これにより運転効率が良くなり省エネ運転が可能となるとともに、蒸発器が乾き室内機から結露水が飛散するといった問題や液バックといった圧縮機の信頼性低下問題を回避することができる。
【００７９】
また、請求項２記載の本発明は、容量可変形圧縮機と室外熱交換器と弁開度を制御可能な複数の電動膨張弁とを有する室外機と、室内熱交換器と前記室内熱交換器の温度を検出する第１の温度検出手段とを有する複数の室内機とを接続配管により並列に接続したマルチタイプの空気調和機において、前記各室内機への各接続配管の配管長を予め記憶する記憶手段と、冷房運転時に前記各室内機の前記第１の温度検出手段により検出された各蒸発温度と前記記憶手段に記憶されている各接続配管の配管長と前記圧縮機の回転数とに基づいて、前記圧縮機の吸入冷媒圧力を推定する第１の推定手段と、室外熱交換器の温度を検出する第２の温度検出手段と、圧縮機の吐出温度を検出する第３の温度検出手段と、前記第２の温度検出手段により検出された凝縮温度と前記第１の推定手段により推定された吸入冷媒圧力に基づいて圧縮機の目標吐出温度を算出する目標吐出温度算出手段と、前記電動膨張弁の開度を制御することにより、前記目標吐出温度を目指して、前記第３の温度検出手段により検出される吐出温度を変更させる膨張弁制御手段とを備えたものである。
【００８０】
このように、マルチタイプの空気調和機においても、蒸発器圧力に圧損を考慮することで運転条件が変化しても圧縮機への吸入冷媒圧力を高精度に推定することができ、高精度に推定された吸入冷媒圧力を使って目標吐出温度を算出し吐出温度を制御するため、運転条件が変化しても高精度に実際の吸入冷媒過熱度を適正過熱度に制御することができる。
【００８１】
これにより運転効率が良くなり省エネ運転が可能となるとともに、蒸発器が乾き室内機から結露水が飛散するといった問題や液バックといった圧縮機の信頼性低下問題を回避することができる。
【００８２】
また請求項３記載の本発明は、圧縮機の吸入温度を検出する第４の温度検出手段と、前記第４の温度検出手段により検出された吸入温度と第１の推定手段で推定された吸入冷媒圧力とから飽和温度を求めるとともに、その飽和温度に基づき前記圧縮機の吸入冷媒過熱度を推定する第２の推定手段と、第３の温度検出手段により検出された吐出温度が目標吐出温度算出手段により算出された目標吐出温度に対し所定範囲内にあり、かつ前記第２の推定手段により推定された圧縮機の吸入冷媒過熱度が所定範囲から外れた場合に、予め記憶手段に記憶されている配管長を修正する配管長修正手段を備えたものである。
【００８３】
このように、予め記憶されている配管長が実際に据付られている配管長と大きく異なる場合でも自動的に配管長を修正するため、修正を行う度に実際の配管長に近づくことになる。この結果、推定された吸入冷媒圧力が修正され、これに伴い目標吐出温度も修正されるため、運転条件や施工条件が変化しても実際の吸入冷媒過熱度は適正過熱度近傍へと修正される。
【００８４】
この結果省エネ運転が可能となり、蒸発器が乾き室内機から結露水が飛散するといった問題や液バックといった圧縮機の信頼性低下問題を回避することができる。
【００８５】
また自動的に配管長を推定することで、施工者が電気回路上に設けたスイッチ等で手動で配管長を設定する必要がなくなり、スイッチ等が不要となることでコストダウンが可能となり、更に配管長の設定ミスや設定忘れによる室内機から結露水が飛散するといった問題や液バックといった圧縮機の信頼性低下問題も回避することができる。
【００８６】
更に吸入冷媒圧力を直接検知する圧力センサの変わりにコストの安い温度センサで済むため、製品のコストを下げることができる。
【００８７】
また請求項４記載の本発明は、室内熱交換器のガス側配管のガス温度を検出する第５の温度検出手段と、前記第５の温度検出手段により検出されたガス温度と第１の温度検出手段により検出された蒸発温度に基づき室内冷媒過熱度を検出する室内冷媒過熱度検出手段と、第３の温度検出手段により検出された吐出温度が目標吐出温度算出手段により算出された目標吐出温度に対し所定範囲内にあり、かつ前記室内冷媒過熱度検出手段により検出された室内冷媒過熱度が所定範囲から外れた場合に予め記憶手段に記憶されている配管長を修正する配管長修正手段を備えたものである。
【００８８】
このように、予め記憶されている配管長が実際に据付られている配管長と大きく異る場合でも自動的に配管長を修正するため、修正を行う度に実際の配管長に近づくことになる。
【００８９】
この結果目標吐出温度が修正され、室内冷媒過熱度も修正されるため、運転条件や施工条件が変化しても実際の吸入冷媒過熱度は適正過熱度近傍へと修正される。
【００９０】
また請求項５記載の本発明は、第２の推定手段により推定された圧縮機の吸入冷媒過熱度が所定値となるよう電動膨張弁の開度を制御する膨張弁制御手段を備えたものである。
【００９１】
このように高精度に推定された吸入冷媒圧力を使って吸入冷媒過熱度を制御するため、運転条件が変化しても高精度に実際の吸入冷媒過熱度を適正過熱度に制御することができる。
【００９２】
これにより運転効率が良くなり省エネ運転が可能となるとともに、液バックといった圧縮機の信頼性低下問題を回避することができる。
【００９３】
また請求項６記載の本発明は、第２の推定手段により推定された圧縮機の吸入冷媒過熱度が所定範囲内にあり、かつ第３の温度検出手段により検出された吐出温度が目標吐出温度算出手段により算出された目標吐出温度に対し所定範囲から外れた場合に、予め記憶手段に記憶されている配管長を修正する配管長修正手段を備えたものである。
【００９４】
このように、予め記憶されている配管長が実際に据付られている配管長と大きく異なる場合でも自動的に配管長を修正するため、修正を行う度に実際の配管長に近づくことになる。この結果、推定された吸入冷媒圧力が修正され、これに伴い運転条件や施工条件が変化しても実際の吸入冷媒過熱度は適正過熱度近傍へと修正される。
【００９５】
また請求項７記載の本発明は、配管長修正手段により修正された配管長が所定配管長から外れた場合、据付配管長が適切ではない旨を使用者に知らせる異常検出手段を備えたものである。
【００９６】
このように、実際に据付られている配管長が適正配管長から逸脱され、システムの運転に不具合が生じやすい場合に使用者にその旨を知らせることができ、この結果システムの重大な損傷等を間逃れることができる。
【図面の簡単な説明】
【図１】本発明の実施形態における空気調和機を示す構成図
【図２】本発明の実施形態におけるマルチタイプの空気調和機を示す構成図
【図３】同吐出温度制御を示すフローチャート
【図４】同吸入過熱度制御時の冷凍サイクル挙動を示すモリエル線図
【図５】同吸入過熱度制御を示すフローチャート
【図６】冷媒循環量と配管長の変化に応じた吸入部圧損特性の相関関係を示す概念図
【図７】吐出温度制御時の冷凍サイクル挙動を示すモリエル線図
【符号の説明】
１室外機
２室内機
３圧縮機
５室外熱交換器
６電動膨張弁
７室内熱交換器
８接続配管
９吐出温度センサ
１０室外熱交換器温度センサ
１１室内熱交換器温度センサ
１２吸入温度センサ
１３室内ガス温度センサ
Ｈ、Ｈａ、Ｈｂ配管長
Ｔｅ、Ｔｅａ、Ｔｅｂ蒸発温度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to control of a separation type air conditioner in which an indoor unit and an outdoor unit are connected by a connection pipe.
[0002]
[Prior art]
As a method of controlling the refrigerant circulation amount of the refrigeration cycle by an electric expansion valve in a conventional separation type air conditioner, for example, Japanese Patent No. 2912254 can be cited.
[0003]
In this conventional example, the target discharge temperature is set on the Mollier diagram by using the evaporation temperature, the condensation temperature, and the slope characteristic line of the compressor alone, and the refrigerant is discharged by the electric expansion valve so that the discharge temperature of the compressor becomes the target discharge temperature. The degree of superheat of the refrigerant is controlled by controlling the amount of circulation.
[0004]
Japanese Patent Application Laid-Open No. 12-292013 discloses a technique for suppressing an increase in the degree of superheat of the refrigerant and preventing the evaporator from becoming too dry by correcting the target discharge temperature based on the evaporation temperature and the refrigerant temperature sucked into the compressor. Is also open to the public.
[0005]
[Problems to be solved by the invention]
By the way, in recent years, from the viewpoints of energy saving and comfort, a separation type air conditioner equipped with an inverter in which the rotation speed of the compressor is greatly changed is widely used. In addition, from the viewpoint of increasing the degree of freedom of installation, the pipe length that can be connected is also required to be shorter and longer.
[0006]
However, in such an air conditioner, the refrigerant circulation amount greatly changes due to the inverter control, and the connection pipe length also greatly changes due to diversification of needs of the indoor unit installation position. As in the pressure loss relationship of the pipe length, the pressure difference between the evaporator pressure and the compressor suction side pressure ("pressure difference" is hereinafter referred to as "pressure loss") changes greatly during the cooling operation.
[0007]
As a result, as shown in the Mollier diagram shown in FIG. 7, even if the target discharge temperature is set only by the evaporation temperature and the condensing temperature, the suction point of the compressor is the point B or C in the figure due to the pressure loss effect of the connecting pipe It was difficult to keep the refrigerant superheat degree on the suction side at an appropriate superheat degree.
[0008]
In general, if the refrigerant superheat degree on the suction side of the compressor is maintained at an appropriate superheat degree (which may vary depending on the type of refrigerant, the operation mode such as cooling / heating, operation frequency, etc.), the operation efficiency of the compressor Becomes higher and energy-saving operation becomes possible.
[0009]
Therefore, when the degree of superheat of the refrigerant becomes too large, there are more portions where the degree of superheat can be obtained in the evaporator, and air that is not dehumidified is mixed with cold air by the blower, and the problem that dew condensation water scatters easily from the indoor unit. On the other hand, if the sucked refrigerant is too wet (the degree of superheat of the refrigerant is not taken at all), a problem of lowering the reliability of the compressor such as a liquid back is likely to occur.
[0010]
Even if the target discharge temperature is corrected with the evaporation temperature of the indoor unit and the suction temperature of the compressor to suppress the degree of superheat of the refrigerant, if the pressure loss in the connection piping changes due to changes in operating conditions (for example, the compressor rotation speed) Can't do enough suppression. Furthermore, when the construction conditions (pipe length) change, the degree of superheat of the refrigerant also changes due to a change in pressure loss.
[0011]
Therefore, it is necessary for the installer to set the actual pipe length with a switch or the like, which causes problems such as an increase in product cost and a longer construction time.
[0012]
Accordingly, the present invention has been made in view of such a point, and an object of the present invention is to estimate the suction refrigerant pressure of the compressor with high accuracy even under various operating conditions and construction conditions during cooling operation. An inexpensive air conditioner that can control the refrigerant superheat degree to an appropriate superheat degree, increase operating efficiency, prevent condensation in the indoor unit, and enhance the reliability of the compressor is provided.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, an air conditioner according to claim 1 is an outdoor unit having a variable capacity compressor, an outdoor heat exchanger, and an electric expansion valve capable of controlling a valve opening, and an indoor heat exchange. In the air conditioner which has an indoor unit which has the 1st temperature detection means which detects the temperature of an indoor unit and the indoor heat exchanger, and the connecting pipe which connects the outdoor unit and the indoor unit, the piping length of the connecting pipe On the basis of the storage means for storing in advance, the evaporation temperature detected by the first temperature detection means during the cooling operation, the pipe length stored in the storage means, and the rotational speed of the compressor. First estimating means for estimating the intake refrigerant pressure, second temperature detecting means for detecting the temperature of the outdoor heat exchanger, third temperature detecting means for detecting the discharge temperature of the compressor, and the second The condensation temperature detected by the temperature detecting means and the first The target discharge temperature calculation means for calculating the target discharge temperature of the compressor based on the suction refrigerant pressure estimated by the estimation means, and by controlling the opening of the electric expansion valve, aiming at the target discharge temperature, Expansion valve control means for changing the discharge temperature detected by the third temperature detection means.
[0014]
In this way, by considering the pressure loss in the evaporator pressure, it is possible to estimate the refrigerant pressure sucked into the compressor with high accuracy even if the operating condition changes, and use the refrigerant refrigerant pressure estimated with high accuracy. Since the target discharge temperature is calculated and the discharge temperature is controlled, the actual intake refrigerant superheat degree can be accurately controlled to an appropriate superheat degree even if the operating conditions change.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
In order to solve the above problems, the present invention according to claim 1 is directed to an outdoor unit having a variable capacity compressor, an outdoor heat exchanger, and an electric expansion valve capable of controlling the valve opening, and an indoor heat exchanger. And an air conditioner having a connection pipe that connects the outdoor unit and the indoor unit, and an air conditioner having a connection pipe that connects the outdoor unit and the indoor unit. Based on the storage means stored in advance, the evaporation temperature detected by the first temperature detection means during cooling operation, the pipe length stored in the storage means, and the rotation speed of the compressor, A first estimating means for estimating the suction refrigerant pressure; a second temperature detecting means for detecting the temperature of the outdoor heat exchanger; a third temperature detecting means for detecting the discharge temperature of the compressor; The condensation temperature detected by the temperature detecting means and the first temperature The target discharge temperature calculation means for calculating the target discharge temperature of the compressor based on the suction refrigerant pressure estimated by the fixing means, and by controlling the opening of the electric expansion valve, aiming at the target discharge temperature, Expansion valve control means for changing the discharge temperature detected by the third temperature detection means.
[0016]
In this way, by considering the pressure loss in the evaporator pressure, it is possible to estimate the refrigerant pressure sucked into the compressor with high accuracy even if the operating condition changes, and use the refrigerant refrigerant pressure estimated with high accuracy. Since the target discharge temperature is calculated and the discharge temperature is controlled, the actual intake refrigerant superheat degree can be accurately controlled to an appropriate superheat degree even if the operating conditions change.
[0017]
According to a second aspect of the present invention, there is provided an outdoor unit having a variable capacity compressor, an outdoor heat exchanger, and a plurality of electric expansion valves capable of controlling valve opening, an indoor heat exchanger, and the indoor heat exchange. In a multi-type air conditioner in which a plurality of indoor units having first temperature detecting means for detecting the temperature of the chamber are connected in parallel by connecting pipes, the pipe length of each connecting pipe to each indoor unit is set in advance Storage means for storing, each evaporating temperature detected by the first temperature detecting means of each indoor unit during cooling operation, pipe length of each connection pipe stored in the storage means, and rotation speed of the compressor Based on the above, a first estimating means for estimating the refrigerant suction pressure of the compressor, a second temperature detecting means for detecting the temperature of the outdoor heat exchanger, and a third temperature detecting means for detecting the discharge temperature of the compressor Detected by temperature detection means and the second temperature detection means By controlling the target discharge temperature calculating means for calculating the target discharge temperature of the compressor based on the condensed condensation temperature and the suction refrigerant pressure estimated by the first estimating means, and the opening degree of the electric expansion valve, An expansion valve control means for changing the discharge temperature detected by the third temperature detection means aiming at the target discharge temperature.
[0018]
As described above, even in the multi-type air conditioner, the refrigerant pressure taken into the compressor can be estimated with high accuracy even if the operating condition changes by considering the pressure loss in the evaporator pressure. Since the target discharge temperature is calculated and the discharge temperature is controlled using the estimated intake refrigerant pressure, the actual intake refrigerant superheat degree can be accurately controlled to an appropriate superheat degree even if the operation condition changes.
[0019]
According to a third aspect of the present invention, there is provided a fourth temperature detecting means for detecting a suction temperature of the compressor, a suction temperature detected by the fourth temperature detecting means, and a suction estimated by the first estimating means. A saturation temperature is obtained from the refrigerant pressure, and the discharge temperature detected by the second estimation means and the third temperature detection means for estimating the intake refrigerant superheat degree of the compressor based on the saturation temperature is calculated as a target discharge temperature. Stored in the storage means in advance when the intake refrigerant superheat degree of the compressor that is within the predetermined range with respect to the target discharge temperature calculated by the means and deviated from the predetermined range is estimated by the second estimating means. A pipe length correcting means for correcting the existing pipe length is provided.
[0020]
In this way, even if the pipe length stored in advance is greatly different from the pipe length that is actually installed, the pipe length is automatically corrected. Therefore, every time correction is performed, the actual pipe length is approached. As a result, the estimated suction refrigerant pressure is corrected, and the target discharge temperature is also corrected accordingly. Therefore, even if the operating conditions and construction conditions change, the actual suction refrigerant superheat degree is corrected to the vicinity of the appropriate superheat degree. The
[0021]
According to a fourth aspect of the present invention, there is provided the fifth temperature detecting means for detecting the gas temperature of the gas side pipe of the indoor heat exchanger, the gas temperature detected by the fifth temperature detecting means and the first temperature. The indoor refrigerant superheat degree detecting means for detecting the indoor refrigerant superheat degree based on the evaporation temperature detected by the detecting means, and the target discharge temperature in which the discharge temperature detected by the third temperature detecting means is calculated by the target discharge temperature calculating means. A pipe length correcting means for correcting the pipe length stored in advance in the storage means when the indoor refrigerant superheat degree detected by the indoor refrigerant superheat degree detecting means is out of the predetermined range. It is provided.
[0022]
In this way, even if the pipe length stored in advance is greatly different from the pipe length that is actually installed, the pipe length is automatically corrected. Therefore, every time correction is performed, the actual pipe length is approached. . As a result, the target discharge temperature is corrected and the indoor refrigerant superheat degree is also corrected, so that the actual intake refrigerant superheat degree is corrected to the vicinity of the appropriate superheat degree even if the operating conditions and the construction conditions change.
[0023]
According to a fifth aspect of the present invention, there is provided expansion valve control means for controlling the opening degree of the electric expansion valve so that the suction refrigerant superheat degree of the compressor estimated by the second estimation means becomes a predetermined value. is there.
[0024]
Since the intake refrigerant superheat degree is controlled using the intake refrigerant pressure estimated with high accuracy in this way, the actual intake refrigerant superheat degree can be accurately controlled to an appropriate superheat degree even if the operating conditions change. .
[0025]
According to the sixth aspect of the present invention, the suction refrigerant superheat degree of the compressor estimated by the second estimating means is within a predetermined range, and the discharge temperature detected by the third temperature detecting means is the target discharge temperature. A pipe length correcting means for correcting the pipe length stored in advance in the storage means when the target discharge temperature calculated by the calculating means deviates from a predetermined range is provided.
[0026]
In this way, even if the pipe length stored in advance is greatly different from the pipe length that is actually installed, the pipe length is automatically corrected. Therefore, every time correction is performed, the actual pipe length is approached. As a result, the estimated intake refrigerant pressure is corrected, and the actual intake refrigerant superheat degree is corrected to the vicinity of the appropriate superheat degree even if the operating conditions and the construction conditions change accordingly.
[0027]
Further, the present invention according to claim 7 is provided with an abnormality detection means for notifying the user that the installation pipe length is not appropriate when the pipe length corrected by the pipe length correction means deviates from the predetermined pipe length. is there.
[0028]
In this way, when the installed pipe length deviates from the appropriate pipe length and the system is likely to malfunction, the user can be notified of this, resulting in serious damage to the system. You can escape.
[0029]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a configuration diagram showing a configuration of an embodiment of the present invention, in which an outdoor unit 1 and an indoor unit 2 are connected by a connection pipe 8 to form a refrigeration cycle.
[0030]
In FIG. 1, an outdoor unit 1 is provided with an inverter-driven variable capacity compressor 3 (hereinafter simply referred to as a compressor), an outdoor heat exchanger 5, and a four-way valve 4 for switching between air conditioning and heating. Is provided with an indoor heat exchanger 7. In addition, an electric expansion valve 6 whose valve opening degree can be controlled by a stepping motor or the like is interposed in the liquid side main pipe of the outdoor unit 1.
[0031]
In the refrigeration cycle having the above configuration, during cooling, the refrigerant discharged from the compressor 3 flows from the four-way valve 4 to the outdoor heat exchanger 5, where it is heat-exchanged with outdoor air to be condensed and liquefied, and then electric The refrigerant is reduced in pressure by passing through the expansion valve 6 so that the refrigerant easily evaporates, flows through the liquid side pipe of the connection pipe 8 to the indoor heat exchanger 7, exchanges heat with the indoor air, evaporates, and then connects. The gas is drawn into the compressor 3 again through the gas side pipe of the pipe 8. Moreover, the rotation speed of the compressor 3 is determined according to the required capacity from the indoor unit 2 (the description is omitted because it is not directly related to the present invention).
[0032]
Next, a method for estimating the suction refrigerant pressure to the compressor 3 will be described.
[0033]
First, the first estimating means (microcomputer) obtains the evaporator pressure Pe based on the saturation pressure conversion using the evaporation temperature Te obtained by the indoor heat exchanger temperature sensor 11, and the pressure loss ΔP from the evaporator pressure Pe. Is reduced to estimate the suction refrigerant pressure Ps.
[0034]
Here, since the amount of refrigerant circulating in the refrigeration cycle is substantially proportional to the rotational speed R of the compressor 3, it is stored in the rotational speed R of the compressor 3 and the storage means (memory device) shown in Equation (2). The pressure loss ΔP is estimated from the length H (for example, 10 m) of the connecting pipe 8.
Ps = Pe−ΔP Equation (1)
ΔP = a × R ² × H (2) (a and b are constants)
Thus, by estimating the pressure loss with high accuracy, the suction refrigerant pressure can also be estimated with high accuracy. Here, the rotation speed R and the pipe length H are used when estimating the pressure loss ΔP, but an evaporation temperature Te or a condensation temperature Tc may be added in order to further improve the accuracy.
(Embodiment 2)
FIG. 2 is a system diagram showing the configuration of an embodiment of the multi-type air conditioner of the present invention. In the case of the multi-type, the first estimating means (microcomputer) has the pipe lengths Ha and Hb stored in the storage means (a and b are added to the subscript because it is a case of a two-chamber multi. Hereinafter, the same applies to Te and the like. ) To calculate the average pipe length Hr [= (Ha + Hb) / 2], to calculate the average rotational speed Rr (= R / 2) of the compressor 3, and from the average pipe length Hr and the average rotational speed Rr The average pressure loss ΔPr is calculated from (2).
[0035]
Then, the average evaporation temperature Ter [= (Tea + Teb) / 2)] is calculated from the respective evaporation temperatures Tea and Teb of the indoor units 2a and 2b, and the average evaporator pressure Pr is obtained by pressure conversion from the average evaporation temperature Ter. The suction refrigerant pressure Ps is estimated from the equation (1) from the average evaporator pressure Pr and the average pressure loss ΔPr. In this way, in the multi-type air conditioner, the average pressure loss is estimated using the average pipe length, so that the overall pressure loss can be estimated with high accuracy, and as a result, the intake refrigerant pressure can also be estimated with high accuracy.
[0036]
Next, the discharge temperature control for indirectly controlling the degree of superheat of the suction refrigerant will be described. First, since the compression principle of the compressor 3 is polytropic compression, the discharge temperature at the appropriate superheat degree SHm can be calculated using the theoretical relational expression of polytropic compression. Therefore, the target discharge temperature calculation means (microcomputer) calculates the discharge refrigerant pressure Pd (function of Tc) of the compressor 3 based on the pressure conversion from the condensation temperature Tc detected by the outdoor heat exchanger temperature sensor 10.
[0037]
From the discharge refrigerant pressure Pd, the suction refrigerant pressure Ps to the compressor estimated by the first estimation means, the saturation temperature conversion Tws (function of Ps) at the suction refrigerant pressure Ps, and the appropriate superheat degree SHm The target discharge temperature Tdm of the compressor 3 is calculated using the theoretical relational expression of Expression (3).
Tdm = (Pd / Ps) ^{(p−1 / p)} × (Tws + SHm + b) −c (3) where p is a polytropic index obtained by experiment, and b and c are constants.
[0038]
Further, the expansion valve control means 1 (microcomputer) sets the operation opening degree ΔK of the electric expansion valve 6 based on the temperature difference ΔT between the discharge temperature Td detected by the discharge temperature sensor 9 and the target discharge temperature Tdm. The electric expansion valve 6 is calculated and controlled every predetermined time (for example, every 60 seconds).
ΔT = Td−Tdm (4)
ΔK = d × ΔT (5) (d is a constant)
In this way, the target discharge temperature is calculated using the intake refrigerant pressure estimated with high accuracy and feedback control is performed, so that the actual intake refrigerant superheat is accurately converted to the appropriate superheat SHm even if the operating conditions change. Can be controlled.
[0039]
In the above description, the pressure conversion is performed using the condensation temperature Tc when calculating the discharge refrigerant pressure Pd. However, in order to further improve the accuracy, it is calculated by adding the term of the rotational speed R of the compressor 3 in the equation (3). May be.
[0040]
Further, the temperature difference ΔT is used for the calculation method of the operation opening degree ΔK of the electric expansion valve 6, but the same effect can be obtained by using a control method such as PID control or fuzzy control.
[0041]
Next, the refrigeration cycle behavior when the actual pipe length actually installed and the pipe length stored in the storage means are greatly different will be described.
[0042]
FIG. 7 shows a Mollier diagram when the above discharge temperature control is performed.
[0043]
In FIG. 7, the cycle written in bold lines indicates the refrigeration cycle when the actual pipe length actually installed and the pipe length stored in the storage means are equal. When the actual pipe length Ht becomes shorter than the pipe length H from here, the actual suction pressure becomes a point B higher than the estimated suction pressure A point, and the actual suction refrigerant superheat degree becomes larger than the appropriate superheat degree SHm.
[0044]
As a result, problems such as a decrease in operating efficiency and the occurrence of dew condensation from the indoor unit are likely to occur. Conversely, when the actual pipe length Ht becomes longer than the pipe length H, the actual suction pressure becomes a point C lower than the estimated suction pressure A point, and the actual suction refrigerant superheat degree becomes smaller than the appropriate superheat degree SHm. As a result, it is easy to cause a problem of lowering the reliability of the compressor, such as a decrease in operating efficiency and a liquid back.
[0045]
Therefore, the discharge temperature control when the actual pipe length Ht actually installed and the pipe length H stored in the storage means are greatly different will be described with reference to a flowchart showing an example of the discharge temperature control in FIG.
[0046]
First, in step S1, the pipe length H is set to an initial value of 10 m, and counters M and N are set to zero. In step S2, the timer for counting the control interval (60 seconds) is reset, and in step S3, the timer is started.
[0047]
In step S4, the suction temperature Ts is read by the evaporation temperature Te, the condensation temperature Tc, the discharge temperature Td, the compressor rotational speed R, and the suction temperature sensor 12. In step S5, the intake refrigerant pressure Ps is estimated by the estimation means 1 or 2, in step S6, the target discharge temperature Tdm is calculated by the target discharge temperature calculation means, and in step S7, the second estimation means uses equation (6). The suction refrigerant superheat degree SHs is estimated.
SHs = Ts−Tws (6)
In step S8, it is determined whether the discharge temperature Td is within ± g ° C. (for example, within 0.5 ° C.) with respect to the target discharge temperature Tdm by the pipe length correcting means 1, and if it is within Tdm ± g ° C., step S9. Proceed to
[0048]
On the other hand, if the discharge temperature Td is not within Tdm ± g ° C. in step S8, the process proceeds to steps S27, S16, S17, and S18, and the expansion valve control means 1 causes the expansion valve control means 1 to set the discharge temperature Td to the target discharge temperature Tdm. The opening operation of 6 is performed. In step S19, after waiting 60 seconds for the timer, the process returns to step S2 again to perform feedback control.
[0049]
In step S9, it is determined whether or not the suction refrigerant superheat degree SHs exceeds the appropriate superheat degree SHm + h (for example, 3K), and if so, the actual pipe length Ht is considered to be shorter than the pipe length H, and in step S10 A counter M for counting the number of times determined to be short is incremented by 1, and a counter N for counting the number of times determined to be long is set to 0.
[0050]
In step S11, it is determined whether the counter M is equal to or greater than α. If the counter M is equal to or greater than α, the suction refrigerant superheat degree SHs exceeds the appropriate superheat degree SHm + h continuously α times (for example, 10 times). It is determined that Ht is shorter than the pipe length H, and the pipe length H is corrected to be shorter by i [m] (for example, 5 [m]) in step S12.
[0051]
Here, the discharge temperature Td is affected by the heat capacity of the compressor 3 and does not stabilize immediately even if the evaporation temperature Te or the condensation temperature Tc is stable. It is possible to prevent erroneous determination when stable.
[0052]
In steps S13 and S14, the suction refrigerant pressure Ps and the target discharge temperature Tdm are recalculated and corrected using the corrected pipe length H. In step S15, after the counter M is reset, the process proceeds to steps S16, S17, and S18, and the opening operation of the expansion valve 6 is performed so that the discharge temperature Td becomes the corrected target discharge temperature Tdm.
[0053]
If the intake refrigerant superheat degree SHs does not exceed the appropriate superheat degree SHm + h in step S9, it is determined in step S20 whether the intake refrigerant superheat degree SHs is below the appropriate superheat degree SHm-h. Assuming that the actual pipe length Ht is longer than the pipe length H, and in the same way, when α continues, the pipe length H, the suction refrigerant pressure Ps, and the target discharge temperature Tdm are corrected in steps S23, S24, S25, and S26. Set to 0.
[0054]
On the other hand, if the suction refrigerant superheat degree SHs is greater than or equal to the appropriate superheat degree SHm-h in step S20, the actual pipe length Ht is considered to be substantially close to the pipe length H, and the pipe length H is controlled without being corrected.
[0055]
By repeatedly correcting the pipe length H as described above, the pipe length H gradually approaches the actual pipe length Ht. As a result, the suction point of the compressor 3 shown in FIG. 7 approaches from the B point or C point to the Ba point or Ca point, and the actual suction refrigerant superheat degree is changed to the appropriate superheat degree SHm even if the construction conditions change. It can be corrected to the vicinity.
[0056]
In the above embodiment, when the discharge temperature Td is within ± g [° C.] with respect to the target discharge temperature Tdm, the correction of the pipe length H is determined using the suction refrigerant superheat degree SHs. The same effect can be obtained by using the detected refrigerant superheat degree.
[0057]
In this case, the indoor refrigerant superheat degree SHi is calculated from the refrigerant gas temperature Tg detected by the indoor gas temperature sensor 13 provided in the gas side pipe of the indoor heat exchanger 7 and the evaporation temperature Te using equation (7).
SHi = Tg−Te (7)
The pipe length correcting means 2 determines the correction of the pipe length H using the value of the indoor refrigerant superheat degree SHi instead of the suction refrigerant superheat degree SHs. The flowchart is substantially the same as that in FIG.
[0058]
In the case of a multi-type air conditioner, each pipe length corrected in step S12 or S23 is i / 2 {Hr = Hr ± i = [(Ha ± i / 2) + (Hb ± i / 2). )] / 2}. In the case of a multi-type air conditioner, it is necessary to control the individual refrigerant circulation amount to each indoor unit simultaneously with the control of the total refrigerant circulation amount.
[0059]
Therefore, after calculating the operation opening degree ΔK (same as all operation units) of the electric expansion valve 6 of each operating unit in step S17, the total opening amount of all the electric expansion valves 6 to which the operation opening degree ΔK is added [ Σ (current opening + ΔK)] is calculated, and the opening degree of each electric expansion valve 6 is set so that the indoor refrigerant superheat degree SHin (n = a machine or b machine) has the same value while maintaining the total opening degree. Is adjusted to the new opening (new opening of unit a + new opening of unit b = total opening), and the opening of each electric expansion valve 6 is operated to the new opening in step S18, thereby controlling the total refrigerant circulation amount. And the control of the individual refrigerant circulation amount to each indoor unit can be performed simultaneously. In this regard, various controls have been proposed and are well known, and are therefore omitted from the flowchart.
[0060]
Further, since the suction refrigerant pressure can be estimated with high accuracy as described above, the suction superheat degree control that directly controls the suction refrigerant superheat degree is also possible. FIG. 4 shows a Mollier diagram in the case where the suction superheat degree control is performed so that the suction refrigerant superheat degree SHs estimated by the estimation means 3 becomes the appropriate superheat degree SHm.
[0061]
In FIG. 4, the cycle written in bold lines indicates the refrigeration cycle when the actual pipe length actually installed and the pipe length stored in the storage means are equal.
[0062]
From this point, when the actual pipe length Ht becomes shorter than the pipe length H, the actual suction pressure becomes a point D higher than the estimated suction pressure A point, and the actual suction refrigerant superheat degree becomes smaller than the appropriate superheat degree SHm. As a result, it is easy to cause a problem of lowering the reliability of the compressor, such as a decrease in operating efficiency and a liquid back.
[0063]
Conversely, when the actual pipe length Ht becomes longer than the pipe length H, the actual suction pressure becomes an E point lower than the estimated suction pressure A point, and the actual suction refrigerant superheat degree becomes larger than the appropriate superheat degree SHm. As a result, problems such as a decrease in operating efficiency are likely to occur.
[0064]
Accordingly, suction superheat control when the actual pipe length Ht actually installed and the pipe length H stored in the storage means are greatly different will be described with reference to a flowchart showing an example of the suction superheat control in FIG. . Steps S1 to S7 are the same as those in the flowchart of FIG.
[0065]
In step S30, it is determined by the pipe length correcting means 3 whether the suction refrigerant superheat degree SHs is within ± j (for example, within 0.5K) with respect to the appropriate superheat degree SHm. If it is within SHm ± j, the process proceeds to step S31. move on. On the other hand, if the suction refrigerant superheat degree SHs is not within SHm ± j in step S30, the process proceeds to steps S27, S33, S34, S18, and the expansion valve control means 2 so that the suction refrigerant superheat degree SHs becomes the appropriate superheat degree SHm. To open the expansion valve 6. In step S19, after waiting 60 seconds for the timer, the process returns to step S2 again to perform feedback control.
[0066]
In step S31, it is determined whether the discharge temperature Td is lower than the target discharge temperature Tdm-k [° C.] (for example, 3 [° C.]). If lower, the actual pipe length Ht is regarded as being shorter than the pipe length H. A counter M that counts the number of times determined to be short in step S10 is incremented by 1, and a counter N that counts the number of times determined to be long is set to 0.
[0067]
In step S11, it is determined whether the counter M is equal to or greater than α. If the counter M is equal to or greater than α, the suction refrigerant superheat degree SHs exceeds the appropriate superheat degree SHm + h continuously α times (for example, 10 times). It is determined that Ht is shorter than the pipe length H, and the pipe length H is corrected to be im (for example, 5 m) shorter in step S12. In steps S13 and S32, the suction refrigerant pressure Ps and the suction refrigerant superheat degree SHs are recalculated and corrected using the corrected pipe length H.
[0068]
In S15, after the counter M is reset, the process proceeds to Steps S33, S34, and S18, and the opening operation of the expansion valve 6 is performed so that the corrected intake refrigerant superheat degree SHs becomes the appropriate superheat degree SHm.
[0069]
If the discharge temperature Td is not lower than the target discharge temperature Tdm-k in step S31, it is determined in step S35 whether the discharge temperature Td is higher than the target discharge temperature Tdm + k. If it is assumed that the length is longer than the length H and is continuously α times, the pipe length H, the suction refrigerant pressure Ps, and the suction refrigerant superheat degree SHs are corrected in steps S23, S24, S36, and S26, and the counter N is set to zero.
[0070]
On the other hand, if the discharge temperature Td is equal to or lower than the target discharge temperature Tdm + k in step S35, the actual pipe length Ht is considered to be substantially close to the pipe length H, and the pipe length H is controlled without being corrected.
[0071]
By repeatedly correcting the pipe length H as described above, the pipe length H gradually approaches the actual pipe length Ht. As a result, the suction point of the compressor 3 shown in FIG. 4 approaches from the D point or E point to the Da point or Ea point, and even if the construction conditions change, the actual suction refrigerant superheat degree is close to the appropriate superheat degree SHm. Can be corrected.
[0072]
In addition, the pipe length actually installed is defined by the minimum pipe length Hmin and the maximum pipe length Hmax in consideration of the reliability of the compressor such as the ratio of the oil and refrigerant of the compressor 3 and the degree of oil return.
[0073]
On the other hand, as described above, the actual pipe length Ht can be estimated by the pipe length correcting means 1, 2 or 3. Therefore, the abnormality detection means (microcomputer) determines whether the pipe length H corrected by the pipe length correction means 1 or 2 or 3 is within an appropriate pipe length from the minimum pipe length Hmin to the maximum pipe length Hmax. When it deviates from within the proper pipe length, an LED lamp 20 (not shown) provided in the indoor unit 2 is used to display that the installed pipe length is not appropriate. Thus, it is possible to notify the installer and the user that the installation pipe length is not appropriate, and it is possible to prompt correction of the piping construction.
[0074]
Here, in addition to the LED lamp 20, it is possible to notify that the installation pipe length is not appropriate by displaying a sound by a buzzer or a remote control. In this way, when the actual installed pipe length deviates from the appropriate pipe length and the system operation is likely to fail, it is possible to avoid serious damages to the system by prompting correction of the piping construction. it can.
[0075]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0076]
The present invention according to claim 1 is an outdoor unit having a variable capacity compressor, an outdoor heat exchanger, and an electric expansion valve capable of controlling a valve opening, an indoor heat exchanger, and a temperature of the indoor heat exchanger. In an indoor unit having a first temperature detecting means for detecting the air, and an air conditioner having a connecting pipe connecting the outdoor unit and the indoor unit, storage means for storing the pipe length of the connecting pipe in advance, cooling A first intake refrigerant pressure is estimated based on the evaporation temperature detected by the first temperature detecting means during operation, the pipe length stored in the storage means, and the rotation speed of the compressor. Estimation means, second temperature detection means for detecting the temperature of the outdoor heat exchanger, third temperature detection means for detecting the discharge temperature of the compressor, and condensation detected by the second temperature detection means Temperature and suction estimated by the first estimating means. Target discharge temperature calculation means for calculating the target discharge temperature of the compressor based on the refrigerant pressure, and the third temperature detection means aiming at the target discharge temperature by controlling the opening of the electric expansion valve. Expansion valve control means for changing the detected discharge temperature.
[0077]
In this way, by considering the pressure loss in the evaporator pressure, it is possible to estimate the refrigerant pressure sucked into the compressor with high accuracy even if the operating condition changes, and use the refrigerant refrigerant pressure estimated with high accuracy. Since the target discharge temperature is calculated and the discharge temperature is controlled, the actual intake refrigerant superheat degree can be accurately controlled to an appropriate superheat degree even if the operating conditions change.
[0078]
As a result, the operation efficiency is improved and energy-saving operation is possible, and the problem that the evaporator dries out and the condensed water scatters from the indoor unit, and the compressor reliability deterioration problem such as the liquid back can be avoided.
[0079]
According to a second aspect of the present invention, there is provided an outdoor unit having a variable capacity compressor, an outdoor heat exchanger, and a plurality of electric expansion valves capable of controlling valve opening, an indoor heat exchanger, and the indoor heat exchange. In a multi-type air conditioner in which a plurality of indoor units having first temperature detecting means for detecting the temperature of the chamber are connected in parallel by connecting pipes, the pipe length of each connecting pipe to each indoor unit is set in advance Storage means for storing, each evaporating temperature detected by the first temperature detecting means of each indoor unit during cooling operation, pipe length of each connection pipe stored in the storage means, and rotation speed of the compressor Based on the above, a first estimating means for estimating the refrigerant suction pressure of the compressor, a second temperature detecting means for detecting the temperature of the outdoor heat exchanger, and a third temperature detecting means for detecting the discharge temperature of the compressor Detected by temperature detection means and the second temperature detection means By controlling the target discharge temperature calculating means for calculating the target discharge temperature of the compressor based on the condensed condensation temperature and the suction refrigerant pressure estimated by the first estimating means, and the opening degree of the electric expansion valve, An expansion valve control means for changing the discharge temperature detected by the third temperature detection means aiming at the target discharge temperature.
[0080]
As described above, even in the multi-type air conditioner, the refrigerant pressure taken into the compressor can be estimated with high accuracy even if the operating condition changes by considering the pressure loss in the evaporator pressure. Since the target discharge temperature is calculated and the discharge temperature is controlled using the estimated intake refrigerant pressure, the actual intake refrigerant superheat degree can be accurately controlled to an appropriate superheat degree even if the operation condition changes.
[0081]
As a result, the operation efficiency is improved and energy-saving operation is possible, and the problem that the evaporator dries out and the condensed water scatters from the indoor unit, and the compressor reliability deterioration problem such as the liquid back can be avoided.
[0082]
According to a third aspect of the present invention, there is provided a fourth temperature detecting means for detecting a suction temperature of the compressor, a suction temperature detected by the fourth temperature detecting means, and a suction estimated by the first estimating means. A saturation temperature is obtained from the refrigerant pressure, and the discharge temperature detected by the second estimation means and the third temperature detection means for estimating the intake refrigerant superheat degree of the compressor based on the saturation temperature is calculated as a target discharge temperature. Stored in the storage means in advance when the intake refrigerant superheat degree of the compressor that is within the predetermined range with respect to the target discharge temperature calculated by the means and deviated from the predetermined range is estimated by the second estimating means. A pipe length correcting means for correcting the existing pipe length is provided.
[0083]
In this way, even if the pipe length stored in advance is greatly different from the pipe length that is actually installed, the pipe length is automatically corrected. Therefore, every time correction is performed, the actual pipe length is approached. As a result, the estimated suction refrigerant pressure is corrected, and the target discharge temperature is also corrected accordingly. Therefore, even if the operating conditions and construction conditions change, the actual suction refrigerant superheat degree is corrected to the vicinity of the appropriate superheat degree. The
[0084]
As a result, energy-saving operation is possible, and problems such as condensation of the evaporator being dried and condensation water being scattered from the indoor unit, and reliability reduction problems of the compressor such as liquid back can be avoided.
[0085]
In addition, by automatically estimating the pipe length, it is not necessary for the installer to manually set the pipe length with a switch etc. provided on the electric circuit, and it becomes possible to reduce costs by eliminating the need for a switch, etc. Problems such as condensed water splashing from indoor units due to setting mistakes or forgetting to set the pipe length, and compressor reliability degradation problems such as liquid back can also be avoided.
[0086]
Further, since a low-cost temperature sensor is sufficient instead of the pressure sensor that directly detects the suction refrigerant pressure, the cost of the product can be reduced.
[0087]
According to a fourth aspect of the present invention, there is provided the fifth temperature detecting means for detecting the gas temperature of the gas side pipe of the indoor heat exchanger, the gas temperature detected by the fifth temperature detecting means and the first temperature. The indoor refrigerant superheat degree detecting means for detecting the indoor refrigerant superheat degree based on the evaporation temperature detected by the detecting means, and the target discharge temperature in which the discharge temperature detected by the third temperature detecting means is calculated by the target discharge temperature calculating means. A pipe length correcting means for correcting the pipe length stored in advance in the storage means when the indoor refrigerant superheat degree detected by the indoor refrigerant superheat degree detecting means is out of the predetermined range. It is provided.
[0088]
In this way, even if the pipe length stored in advance is greatly different from the pipe length that is actually installed, the pipe length is automatically corrected. Therefore, every time correction is performed, the actual pipe length is approached. .
[0089]
As a result, the target discharge temperature is corrected and the indoor refrigerant superheat degree is also corrected, so that the actual intake refrigerant superheat degree is corrected to the vicinity of the appropriate superheat degree even if the operating conditions and the construction conditions change.
[0090]
According to a fifth aspect of the present invention, there is provided expansion valve control means for controlling the opening degree of the electric expansion valve so that the suction refrigerant superheat degree of the compressor estimated by the second estimation means becomes a predetermined value. is there.
[0091]
Since the intake refrigerant superheat degree is controlled using the intake refrigerant pressure estimated with high accuracy in this way, the actual intake refrigerant superheat degree can be accurately controlled to an appropriate superheat degree even if the operating conditions change. .
[0092]
As a result, the operation efficiency is improved, energy saving operation is possible, and the problem of reliability reduction of the compressor such as liquid back can be avoided.
[0093]
According to the sixth aspect of the present invention, the suction refrigerant superheat degree of the compressor estimated by the second estimating means is within a predetermined range, and the discharge temperature detected by the third temperature detecting means is the target discharge temperature. A pipe length correcting means for correcting the pipe length stored in advance in the storage means when the target discharge temperature calculated by the calculating means deviates from a predetermined range is provided.
[0094]
In this way, even if the pipe length stored in advance is greatly different from the pipe length that is actually installed, the pipe length is automatically corrected. Therefore, every time correction is performed, the actual pipe length is approached. As a result, the estimated intake refrigerant pressure is corrected, and the actual intake refrigerant superheat degree is corrected to the vicinity of the appropriate superheat degree even if the operating conditions and construction conditions change accordingly.
[0095]
Further, the present invention according to claim 7 is provided with an abnormality detection means for notifying the user that the installation pipe length is not appropriate when the pipe length corrected by the pipe length correction means deviates from the predetermined pipe length. is there.
[0096]
In this way, when the installed pipe length deviates from the appropriate pipe length and the system is likely to malfunction, the user can be notified of this, resulting in serious damage to the system. You can escape.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an air conditioner according to an embodiment of the present invention. FIG. 2 is a block diagram showing a multi-type air conditioner according to an embodiment of the present invention. 4] Mollier diagram showing the refrigeration cycle behavior during the same intake superheat control. [FIG. 5] Flow chart showing the same intake superheat control. [FIG. Schematic diagram showing the relationship [Fig. 7] Mollier diagram showing the refrigeration cycle behavior during discharge temperature control [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outdoor unit 2 Indoor unit 3 Compressor 5 Outdoor heat exchanger 6 Electric expansion valve 7 Indoor heat exchanger 8 Connection piping 9 Discharge temperature sensor 10 Outdoor heat exchanger temperature sensor 11 Indoor heat exchanger temperature sensor 12 Suction temperature sensor 13 Indoor Gas temperature sensors H, Ha, Hb Pipe length Te, Tea, Teb Evaporation temperature

Claims

An outdoor unit having a variable capacity compressor, an outdoor heat exchanger, and an electric expansion valve whose valve opening degree can be controlled, and a first temperature detecting means for detecting temperatures of the indoor heat exchanger and the indoor heat exchanger, respectively. An air conditioner having a connection pipe for connecting the outdoor unit and the indoor unit, a storage means for storing in advance a predetermined pipe length of the connection pipe, and the first temperature detection means during cooling operation First estimation means for estimating the suction refrigerant pressure of the compressor based on the heat exchanger temperature detected by the above, the pipe length stored in the storage means, and the rotation speed of the compressor, and outdoor heat exchange Second temperature detecting means for detecting the temperature of the compressor, third temperature detecting means for detecting the discharge temperature of the compressor, the condensation temperature detected by the second temperature detecting means, and the first estimating means Based on the suction refrigerant pressure estimated by A target discharge temperature calculating means for calculating a target discharge temperature of the compressor and a discharge temperature detected by the third temperature detecting means for changing to the target discharge temperature by controlling an opening degree of the electric expansion valve. An air conditioner comprising expansion valve control means.

A plurality of indoor units having an indoor heat exchanger and a first temperature detecting means for detecting the temperature of the indoor heat exchanger, variable capacity compressors and outdoor heat exchangers, and refrigerant flow rates for the indoor units. In a multi-type air conditioner in which an outdoor unit having a plurality of electric expansion valves capable of controlling the valve opening for control is connected in parallel by a connection pipe, each connection pipe to each indoor unit is Storage means for preliminarily storing a predetermined pipe length; evaporating temperatures detected by the first temperature detecting means of the indoor units during cooling operation; pipe lengths of connection pipes stored in the storage means; Based on the rotational speed of the compressor, first estimation means for estimating the refrigerant suction pressure of the compressor, second temperature detection means for detecting the temperature of the outdoor heat exchanger, and the discharge temperature of the compressor Third temperature detecting means for detecting; and Target discharge temperature calculating means for calculating a target discharge temperature of the compressor based on the condensing temperature detected by the second temperature detecting means and the suction refrigerant pressure estimated by the first estimating means; and opening of the electric expansion valve An air conditioner comprising expansion valve control means for changing the discharge temperature detected by the third temperature detection means so as to achieve the target discharge temperature by controlling the degree.

A saturation temperature is obtained from the fourth temperature detection means for detecting the suction temperature of the compressor, the suction temperature detected by the fourth temperature detection means and the suction refrigerant pressure estimated by the first estimation means; A second estimating means for estimating the refrigerant superheat degree of the compressor based on the saturation temperature; and a discharge temperature detected by the third temperature detecting means with respect to the target discharge temperature calculated by the target discharge temperature calculating means. Pipe length correcting means for correcting the pipe length stored in the storage means in advance when the intake refrigerant superheat degree of the compressor estimated by the second estimating means is out of the predetermined range. The air conditioner according to claim 1 or 2, further comprising:

Based on the fifth temperature detecting means for detecting the gas temperature of the gas side pipe of the indoor heat exchanger, the gas temperature detected by the fifth temperature detecting means and the evaporation temperature detected by the first temperature detecting means. The indoor refrigerant superheat detection means for detecting the indoor refrigerant superheat degree, the discharge temperature detected by the third temperature detection means is within a predetermined range with respect to the target discharge temperature calculated by the target discharge temperature calculation means, and The air according to claim 1 or 2, further comprising a pipe length correcting means for correcting a pipe length stored in advance in the storage means when the indoor refrigerant superheat degree detected by the indoor refrigerant superheat degree detecting means is out of a predetermined range. Harmony machine.

The expansion valve control means for controlling the opening degree of the electric expansion valve so that the suction refrigerant superheat degree of the compressor estimated by the second estimation means becomes a predetermined value. Air conditioner.

The suction refrigerant superheat degree of the compressor estimated by the second estimating means is within a predetermined range, and the discharge temperature detected by the third temperature detecting means is the target discharge temperature calculated by the target discharge temperature calculating means. 6. The air conditioner according to claim 5, further comprising a pipe length correcting means for correcting the pipe length stored in the storage means in advance when the predetermined range is not met.

7. An abnormality detecting means for notifying the user that the installed pipe length is not appropriate when the pipe length corrected by the pipe length correcting means deviates from the predetermined pipe length. An air conditioner according to any one of the above.