JP3736969B2

JP3736969B2 - Air conditioner

Info

Publication number: JP3736969B2
Application number: JP13794998A
Authority: JP
Inventors: 佳宏高橋; 憲和石川; 毅小坂井; 敏也布施
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1998-05-20
Filing date: 1998-05-20
Publication date: 2006-01-18
Anticipated expiration: 2018-05-20
Also published as: JPH11325639A

Description

【０００１】
【発明の属する技術分野】
この発明は、室内機を複数台備えた、いわゆる室内マルチ型の空気調和機に関するものである。
【０００２】
【従来の技術】
従来、室内マルチ型の空気調和機においては、暖房時において休止室内機があると一部の冷媒が休止室内機に流れて放熱されるため、運転側室内機の性能が低下する問題がある。
この問題を解決するために、室内機各々に電子式膨張弁を設けると共に、暖房時における休止室内機の膨張弁を、同室内機における熱交換器の冷媒出入口温度の差により冷媒溜まり込みがない程度にできるだけ少しづつしか流れないように膨張弁の開度を最小開度に制御し、これにより運転側室内機の性能低下を防止すると共に、休止室内機側に冷媒が溜り込んで冷媒不足になる様なことを防止するようにしている。
【０００３】
図１０は、例えば実開昭６２−４３２６９号公報に示された上記した従来の室内マルチ型空気調和機の構成を示す冷媒回路図である。
図において、空気調和機は２つの室内機Ａ，Ｂユニットより構成されており、ここで、１は圧縮機、２は四方弁、３は冷媒配管、４ａはＡユニットの室内熱交換器、４ｂはＢユニットの室内熱交換器、５ａ，５ｂはマイコン等を利用して自由に開度調整できる電子式膨張弁、６は冷媒配管、９は室外熱交換器、１３はアキュームレータ、１１ａ，１１ｂは室内ファン、１２は室外ファンであり、また室内熱交換器４ａ，４ｂの入口および出口の配管に取り付けられた入口および出口冷媒温度センサ１０１ａ，１０１ｂ，１０２ａ，１０２ｂで構成されており、冷媒が実線矢印の如く流れることにより暖房運転がなされ、点線矢印の如く流れることにより冷房運転がなされる。
【０００４】
以上のように構成された冷媒回路において、暖房運転時Ａユニットが運転され、Ｂユニットが休止されて室内ユニットが一台しか運転されていない時は、Ｂユニットの膨張弁５ｂの開度をＢユニットの熱交換器の冷媒出入口温度の差により、同温度差が適温となるように、すなわち冷媒が室内交換器４ｂに溜り込まない程度にできるだけ少しづつしか流れないように膨張弁５ｂの開度を決めてやる。
この時の膨張弁の開度決定は、室内熱交換器４ｂの入口および出口に取付けられた冷媒温度センサ１０１ｂ，１０２ｂの検出温度をそれぞれＴ１，Ｔ２とした時、その温度差（Ｔ１−Ｔ２）が適温となるよう休止側のＢユニットの膨張弁５ｂの開度を決定することにより成され、図１０の実線矢印に示すように冷媒が流れる。
【０００５】
なお、膨張弁５ａ，５ｂは０（全閉）〜１００（全開）％まで開度を調整できる電子式の膨張弁が使用されている。
今、暖房運転が開始されると図１０に示す実線矢印の方向に冷媒が流れ、四方弁、冷媒配管３、３ａ，３ｂを通り室内熱交換器４ａ，４ｂで熱交換され冷却されて液冷媒となる。
この液冷媒は膨張弁５ａ，５ｂで一回減圧され、冷媒配管６ａ，６ｂから６を経て膨張弁７で更に減圧され室外熱交換器９で加熱されてガス冷媒となり、四方弁２、アキュームレータ１３を通って圧縮機１へ戻る。
【０００６】
ここで、一方の室内熱交換器ユニットであるＢユニットが休止の場合の膨張弁５ａ，５ｂの開度決定のコントロールを説明する。
暖房運転が始まるとコントローラ１００は室内熱交換器ユニットの運転が１台か２台かを確認し、２台だと各々決められた膨張弁開度となるように膨張弁５ａ，５ｂに開度を指示する。
【０００７】
次に暖房運転はＡユニット１台だとすると、Ａユニットは決められた膨張弁５ａの開度となるが、Ｂユニットの膨張弁５ｂの開度は一旦０（全閉）とされる。しかし小時間経過後、膨張弁５ｂは少し開けられ室内熱交換器４ｂの入口と出口の配管の冷媒温度センサ１０１ｂの温度Ｔ１と、１０２ｂの温度Ｔ２を検知してＴ１−Ｔ２を計算し、この値が熱交換器への冷媒溜まり込み量がない程度の時に示す設定値と比較し、この設定値より小さければ熱交換器には冷媒が溜まり込んでいると判断して膨張弁５ｂの開度は更に少し開けられ、Ｔ１−Ｔ２が設定値になるまで繰り返す。すなわちＴ１−Ｔ２の値が設定温度範囲内に保たれるように膨張弁５ｂの開度は制御される。
【０００８】
なお、冷房運転時には暖房運転時におけるような冷媒の溜まり込みは発生しないので、休止ユニットがあれば休止側の膨張弁は単に閉とされる。
また、通常Ａユニット、Ｂユニットの両方が暖房運転される場合は、公知の如くＡ，Ｂユニットのそれぞれの負荷によって各々膨張弁５ａ，５ｂの開度は決まるのでこの説明は省略する。
【０００９】
【発明が解決しようとする課題】
上記に説明したように、従来の室内マルチ型の空気調和機においては、暖房時において休止ユニットがある場合、休止ユニットへの冷媒の溜まり込みを防止するために室内熱交換器の入口と出口の配管に取付けられた冷媒温度センサの温度差により電子式膨張弁の開度を制御している。
【００１０】
しかしながら、通常圧縮機から吐出され室内交換器に流入する冷媒は過熱ガス状態であり、膨張弁の開度を適正開度（最小開度）とするためには、膨張弁の開度を一旦０（全閉）とし、凝縮させた液冷媒を一旦室内熱交換器および室内熱交換器の出口配管部に溜め込まなければならず、適正開度へ開度制御できれば溜まり込んだ冷媒は回収できるが初期時における正常運転を維持するためにはかなり多量の冷媒量が必要であり、結果的に封入冷媒量を多くしなければならないと言う問題があった。
【００１１】
また、室内熱交換器の入口と出口の配管温度差（冷媒温度差）で電子膨張弁の制御をしているため、適正開度となった時の冷媒の室内熱交換器への溜まり込み状態は、室内熱交換器の出口部まで達していないと言うだけであって、膨張弁の開度を０（全閉）から開度制御しているため通常最小開度で安定しても室内熱交換器内には相当量の冷媒の溜まり込みがあり、正常な空気調和機の運転を維持するためには、この溜まり込む冷媒量を考慮した封入冷媒量とする必要があり、結果として封入冷媒量が多くなると言った問題があった。
【００１２】
また、暖房時における休止ユニットが送風運転を行った場合、膨張弁は最小開度で制御されて圧縮機から供給される少量の冷媒を流しており、この圧縮機から供給される冷媒は通常は過熱ガスであり室内熱交換器で凝縮し液冷媒となって室外熱交換器のユニットへ返されるが、その時の凝縮による放熱分が送風運転の吹出し温度の上昇につながり、室内熱交換器の入口と出口との配管温度差（冷媒温度差）による膨張弁開度の制御では室内吸込み温度に対する吹出し温度の上昇度が把握できないと言う問題があり、吹出し温度の上昇を成り行きまかせにせざるを得ないと言った問題があった。
【００１３】
【課題を解決するための手段】
この発明は、上記の問題を解決するためになされたもので、室内マルチ型の空気調和機において、暖房運転時に室内ユニットの吸込み温度を検出する吸込み温度センサと、室内熱交換器の出口もしくは中央冷媒温度を検出する出口冷媒温度センサ、中央冷媒温度センサと、冷媒流量を制御する電子式膨張弁を備えることにより、暖房運転時における休止ユニットの冷媒の溜まり込みの判定を、室内熱交換器の出口冷媒温度もしくは中央冷媒温度と室内吸込み温度の温度差により検出し、その結果に照らして電子式膨張弁の開度を適正に制御し、室内熱交換器への冷媒の溜まり込みを防止して、封入冷媒量を抑制すると共に、暖房運転時において休止且つ送風状態に設定された休止側室内機の熱交換器の出口冷媒温度と吸込み温度との温度差により、膨張弁開度を変化させ、吹出し温度の吸込み温度に対する上昇度と、予め設定された温度設定値と比較し、設定温度より小さくなるように膨張弁の開度を少しづつ調整を繰り返して、膨張弁の開度を制御することにより吹出し温度を調整することを特徴とする空気調和機を提供するものである。
【００１４】
上記の手段によるこの発明においては、空気調和機が暖房運転で暖房運転ユニットと、休止ユニットとが混在する時、休止ユニットの電子式膨張弁の所定開度は０％（全閉）に近い微小開度に設定し、次いで休止ユニットの熱交換器の出口冷媒温度と休止ユニットの吸込み温度との温度差を検出して予め設定した所定の設定値と比較して、その値が所定値以下ならば電子式膨張弁の開度を一定量アップする。
【００１５】
この操作を定期的に繰り返し、休止ユニットの熱交換器の出口冷媒温度と休止ユニットの吸込み温度との温度差が所定の設定値を越えたら電子式膨張弁の開度は安定することになる。
【００１６】
このように電子式膨張弁の開度を制御することによって、休止ユニットの室内熱交換器に溜まり込む冷媒量を、室内熱交換器に溜り込む以前に冷媒の溜り込みを検出することによって最低限にすることができ、冷媒の封入量を抑制するとともに冷媒の溜り込みによる冷媒不足も防止することができる。
【００１７】
また、休止ユニットが単に送風運転している場合には、吹出し温度を熱交換器の中央冷媒温度から検出し、予め設定した所定の設定値と比較して、その値が所定値以下ならば電子式膨張弁の開度を一定量絞る。この操作を定期的に繰り返し、休止ユニットの熱交換器の中央冷媒温度と休止ユニットの吸込み温度との温度差が所定の設定値以下になれば電子式膨張弁の開度は安定することになる。
このように電子式膨張弁の開度を制御することによって、室温の上昇を抑制し快適性を向上させることができる。
【００１８】
【発明の実施の形態】
実施の形態１．
以下、この発明の第１の実施の形態を図１から図５を用いて説明する。図１は第１の実施の形態による空気調和機の系統構成図である。図において空気調和機は室外機ユニットＣと、２つの室内機でユニットＡ，Ｂより構成されている。
ここで、１は圧縮機、２は四方弁、３は冷媒配管、４ａはユニットＡの室内熱交換器、４ｂはユニットＢの室内熱交換器、５ａ，５ｂはマイコン等を利用して自由に開度を調整できる電子式膨張弁、６は冷媒配管、９は室外熱交換器、１１ａ，１１ｂは室内ファン、１２は室外ファン、１３はアキュームレータ、１０２ａ，１０２ｂは室内熱交換器４ａ，４ｂの出口配管に取付けられた出口冷媒温度センサ、１０３ａ，１０３ｂは室内ユニットＡ，Ｂの各々の吸込み空気の温度を検出することができる個所に取付けられた吸込み温度センサ、１００は上記出口冷媒温度センサ１０２ａ，１０２ｂ，および吸込み温度センサ１０３ａ，１０３ｂ，および電子式膨張弁５ａ，５ｂを制御するコントローラで構成されており、冷媒が実線矢印の如く流れることにより暖房運転がなされる。
【００１９】
このように構成された空気調和機の暖房運転時において、室内ユニットＡは暖房運転，室内ユニットＢは休止とすると、休止ユニットである室内ユニットＢは室内空調空間の温度分布の均一化を図るために送風運転をしている。そして、この状態における休止ユニットである室内ユニットＢの電子式膨張弁５ｂの開度は、冷媒が室内熱交換器４ｂ等に溜まり込まない程度に、すなわち冷媒が溜まり込まない程度にできるだけ少しづつしか流れないような開度に決めてやる。以下にこの場合における電子式膨張弁５ｂの開度決定の一連の動作について説明する。
なお、電子式膨張弁５ａ，５ｂは０（全閉）〜１００％（全開）までの開度調整をマイコン等でコントロールできる膨張弁が使用されているもので、これら電子式膨張弁５ａ，５ｂは以下の説明では単に膨張弁と略記する。
【００２０】
まず、暖房運転が開始されると図１に示す矢印の方向に冷媒は流れ、四方弁２、冷媒配管３、３ａ，３ｂを通り室内熱交換器４ａ，４ｂで熱交換されて液冷媒となり、膨張弁５ａ，５ｂで減圧され、冷媒配管６ａ，６ｂ、６を経て室外熱交換器９で加熱されガス冷媒となり、四方弁２、アキュームレータ１３を経て圧縮機１へ戻る。
【００２１】
暖房運転が始まるとコントローラ１００は室内器の運転が１台か、２台かを確認し、ユニットＢは休止、ユニットＡの１台だけが暖房運転だとすると、運転側の室内ユニットＡはその与えられた負荷に応じた膨張弁開度になるよう膨張弁５ａが開度指示され、休止側の室内ユニットＢの膨張弁５ｂの開度は次に述べる所定の値に設定される。
【００２２】
この時の休止ユニットである室内ユニットＢに与えられる膨張弁開度について図２を用いて説明する。
図２は、休止ユニット（ただし送風運転）に与える膨張弁開度と冷媒流量、吹出し空気温度の吸込み温度に対する上昇温度、休止側の室内熱交換器に溜り込む冷媒量の関係を示す特性図である。
【００２３】
この図２によれば、休止ユニットに与える膨張弁開度が０％（全閉）の場合、休止ユニットに流れる冷媒量、および吹出し温度に対する上昇温度は共に０となるが、室内熱交換器に溜まり込む冷媒量は最大となる。膨張弁の開度を０％（全閉）から開いて行くと、室内熱交換器に溜まり込む冷媒量は減少して行くが、休止ユニットに流れる冷媒流量は増加し、吹出し温度の吸込み温度に対する上昇度も増加する。
【００２４】
一般的に膨張弁の開度に対する室内熱交換器に溜まり込む冷媒量の増加と、吹出し温度の吸込み温度に対する上昇度は相反する関係にあり、その他の与えられた条件を含めて最も適切な膨張弁の開度を選択するのが通常であり、個々の空気調和機において適切と言える休止ユニットの膨張弁開度が存在する。
【００２５】
図３は膨張弁の流量のばらつき特性を示した概念図である。
一般的に膨張弁には機械的な製造誤差による影響と、経年変化による影響により冷媒流量のずれ（流量ばらつき）が発生する。従って、図２に示す室内熱交換器への冷媒溜まり込み量と、吹出し温度の吸込み温度に対する上昇度の関係から適切な休止ユニットの膨張弁開度を決定しても、図３に示すように冷媒流量のずれが発生するため必ずしも適切な休止ユニットの膨張弁開度が得られるとは限らないと言った別の問題が発生する。
【００２６】
また、流量０となる膨張弁の開度は必ずしも開度０％ではなく、ある程度の開度になった時点で冷媒の流量が得られる特性となる膨張弁が多く、上記の流量のずれにより流量０となる膨張弁開度もずれ（膨張弁開度ばらつき）が発生する。
【００２７】
以上の点から休止ユニットの膨張弁開度は、図２より得られた冷媒が多量に溜まり込まない程度の微小な値、すなわち適正膨張弁開度よりも低めに設定されるのが通例である。
しかし、同時に冷媒流量を微小とする目的のために膨張弁開度を低めの設定にしすぎると、膨張弁開度のずれ（膨張弁開度のばらつき）により流量０となり、室内熱交換器に溜まり込む冷媒量が大となってしまう可能性が高くなる。
また、流量０を回避するために膨張弁開度を高めに設定すると室内熱交換器に溜まり込む冷媒量は少なくなるが、冷媒の流量が増大し、吹出し温度の吸込み温度に対する上昇度が大きくなってしまう。
【００２８】
そこで、適切な膨張弁開度を得るための手段を図５に基づいて以下に説明する。
図５は膨張弁開度の決定手順を示すフローチャートで、休止ユニットＢの膨張弁開度を所定の開度に設定後、圧縮機を運転し、室内熱交換器の出口冷媒温度センサ１０２ｂにより出口冷媒温度Ｔ２を検出すると共に、吸込み温度センサ１０３ｂにより吸込み温度Ｔ１を検出する。そして、出口冷媒温度と吸込み温度との温度差（Ｔ２−Ｔ１）を計算し、この温度差（Ｔ２−Ｔ１）が予め設定された温度の設定値と比較し、設定温度より小さければ熱交換器には冷媒が溜まり込んでいるので、膨張弁開度を少し開けるように修正する。
【００２９】
つぎに、再度、出口冷媒温度と吸込み温度との温度差（Ｔ２−Ｔ１）を計算し、この温度差（Ｔ２−Ｔ１）が予め設定された温度の設定値と比較し、設定温度より小さければ膨張弁開度を少し開けるように修正する。このように膨張弁開度を少しづつ調整して上記の出口冷媒温度と吸込み温度との温度差（Ｔ２−Ｔ１）の値が設定値以上になるまで繰り返す。
【００３０】
ここで、図４を用いて温度差（Ｔ２−Ｔ１）の設定値について説明する。
図4は膨張弁の開度変化に対する運転特性を示したもので、休止ユニットが送風運転を実施している場合、風量は通常の暖房運転時とほぼ等しく室内熱交換器の熱交換能力は暖房運転とほぼ等しくなっている。
休止ユニットの場合、通常の暖房運転の時と比較し膨張弁開度は極めて小さく設定され、冷媒流量はごく僅かな量となる。暖房時室内熱交換器は圧縮機から流れてくる高温過熱ガスを冷却し液冷媒とするが、休止ユニットの場合、暖房運転時と比較し熱交換能力はほぼ等しいにも拘わらず（暖房運転時の冷媒流量）＞＞(休止時の冷媒流量)となっているため、休止ユニットの冷媒は通常の暖房時に比べて遥かに冷却する。
【００３１】
この関係は冷媒流量を決定する膨張弁開度と密接な関係にあり、膨張弁開度を小さくして行くほど冷媒温度は低下し、ある開度からは吸込み温度と冷媒温度とが一致する。この特性を利用して冷媒流量および冷媒が流れているか否かの判断が可能であり、ほぼ適正な冷媒流量を確保するための熱交換器の出口冷媒温度と吸込み温度との温度差（Ｔ２−Ｔ１）の値の範囲を決定し、膨張弁開度を制御することによって最終的に最適開度を得ることができる。
【００３２】
従って、上記した特性の相関を利用して、膨張弁開度の最適値を設定すると共に、この最適値と熱交換器の出口冷媒温度と吸込み温度との温度差（Ｔ２−Ｔ１）の値とを比較して膨張弁の開度を修正して、繰り返し調整を行い最適な膨張弁開度に到達することができると共に、膨張弁の機械的公差のばらつき、および経時劣化による開度のずれに対してもその影響を排除することができる。
なお、この実施の形態における目的を達成する上で、室内熱交換器の出口冷媒温度センサ１０２ａ，１０２ｂは膨張弁と室内熱交換器を接続する配管のいずれかの個所に設置すれば良いものである。
【００３３】
実施の形態２．
この発明の第１の実施の形態においては、熱交換器の出口冷媒温度と吸込み温度との温度差（Ｔ２−Ｔ１）の値とを比較して膨張弁の開度を決定したが、図１の冷媒回路構成により、暖房運転および暖房休止ユニットの吹出し温度の制御を行うことができる。すなわち、室内熱交換器４ａ，４ｂ、室内熱交換器の出口冷媒温度センサ１０２ａ，１０２ｂ、および室内吸込み温度センサ１０３ａ，１０３ｂにおいて、室内吸込み温度センサ１０３ａ，１０３ｂにより検出された室内吸込み温度に対する熱交換器の出口冷媒温度を出口冷媒温度センサ１０２ａ，１０２ｂにより検出し、吸込み温度に対する吹出し温度の上昇度の相関、および吹出し温度に対する出口冷媒温度との相関から吹出し温度そのものを膨張弁開度によって制御することが可能となる。
【００３４】
図６および図７は、この実施の形態２を説明するための膨張弁開度変化に対する運転特性を示したもので、図６により膨張弁開度を大きくすることによって冷媒流量が増大し、吹出し温度は上昇し、結果として（吹出し温度−吸込み温度）は上昇する特性となる。この特性を利用して、熱交換器の出口冷媒温度と吸込み温度との温度差（Ｔ２−Ｔ１）により図８の膨張弁開度の決定手順を示すフローチャートのように膨張弁開度を変化させ、吹出し温度の吸込み温度に対する上昇度と、予め設定された温度設定値と比較し、設定温度より小さくなるように膨張弁の開度を少しづつ調整を繰り返して、膨張弁の開度を制御することにより吹出し温度を調整でき、結果として休止ユニットの室温の上昇を抑制することができ、快適性の向上につなげることができる。
【００３５】
また、図７により膨張弁開度を変化させた時の熱交換器の出口冷媒温度Ｔ２と吹出し温度の変化の特性を利用して、この相関から熱交換器出口冷媒温度Ｔ２を膨張弁開度でコントロールすることによって吹き出し温度を制御することもできる。
【００３６】
実施の形態３．
次に、この発明の第３の実施の形態を図９を用いて説明する。図９は実施の形態１に用いた図１の冷媒回路に対して、室内熱交換器の出口冷媒温度センサ１０２ａ，１０２ｂの代わりに室内熱交換器の中央冷媒温度を検出するための中央冷媒温度センサ１０４ａ，１０４ｂを取付けることにより、（室内熱交換器の中央冷媒温度−吸込み温度）を検出し、この値と予め設定した温度と比較して前記した実施の形態１および実施の形態２と同様に膨張弁開度の制御行って適正な膨張弁の開度を決定することができる。
【００３７】
【発明の効果】
この発明によれば、各々個別に運転、休止できる複数台の室内機を備えた空気調和機において、前記室内機に各々電子式膨張弁と、熱交換器の出口冷媒温度を検出する出口冷媒温度センサ、および吸込み温度を検出する吸込み温度センサとを備えてなり、暖房運転時において休止側室内機の熱交換器の出口冷媒温度と、吸込み温度との温度差を検出し、この温度差が予め設定された温度の設定値と比較し、設定温度より小さければ膨張弁開度を少し開けるように修正し、前記温度差の値が設定値以上になるまで繰り返し調整を行い、冷媒の溜まり込みがないように前記電子式膨張弁を適正開度に制御するとともに、暖房運転時において休止且つ送風状態に設定された休止側室内機の熱交換器の出口冷媒温度と吸込み温度との温度差により、膨張弁開度を変化させ、吹出し温度の吸込み温度に対する上昇度と、予め設定された温度設定値と比較し、設定温度より小さくなるように膨張弁の開度を少しづつ調整を繰り返して、膨張弁の開度を制御することにより吹出し温度を調整するものである。これによって休止ユニットの室内熱交換器への冷媒の溜まり込み量を最低限にすることが可能となり、さらには空気調和機に封入する冷媒量を最低限に抑制しつつ、かつ冷媒不足での運転をも防止することができる。
また、膨張弁の機械的公差によるばらつきや経時劣化による冷媒流量のずれに対しても、常に最適な膨張弁の開度となるように制御することが可能となり、その影響を排除することができる。
【００３８】
また、室内熱交換器の暖房時における暖房運転ユニット、および休止ユニットに対して室内熱交換器の出口冷媒温度もしくは中央冷媒温度と吸込み温度との温度差により、膨張弁開度を変化させ、吹出し温度の吸込み温度に対する上昇度と、予め設定された温度設定値と比較し、設定温度より小さくなるように膨張弁の開度を少しづつ調整を繰り返して、膨張弁の開度を制御することにより吹出し温度を調整でき、結果として休止ユニットの室温の上昇を抑制することができ、快適性の向上が図れる。
【図面の簡単な説明】
【図１】この発明による第１の実施の形態の系統構成を示す図である。
【図２】この発明による第１の実施の形態における膨張弁開度変化に対する空気調和機の運転特性を示す図である。
【図３】この発明による第１の実施の形態における膨張弁開度変化と冷媒流量の関係特性を示す説明図である。
【図４】この発明による第１の実施の形態における膨張弁開度変化に対する空気調和機の運転特性を示す説明図である。
【図５】この発明による第１の実施の形態における膨張弁開度の決定手順を示すフローチャートである。
【図６】この発明による第２の実施の形態における膨張弁開度変化に対する空気調和機の運転特性を示す図である。
【図７】この発明による第２の実施の形態における膨張弁開度変化に対する空気調和機の運転特性を示す図である。
【図８】この発明による第２の実施の形態における膨張弁開度の決定手順を示すフローチャートである。
【図９】この発明による第３の実施の形態の系統構成を示す図である。
【図１０】従来の空気調和機の系統構成を示す図である。
【符号の説明】
１圧縮機、２四方弁、３，３ａ，３ｂ冷媒配管、４ａ，４ｂ室内熱交換器、５ａ，５ｂ電子式膨張弁、６，６ａ，６ｂ冷媒配管、９室外熱交換器、１１ａ，１１ｂ室内送風機、１２室外送風機、１００コントローラ、１０２ａ，１０２ｂ出口冷媒温度センサ、１０３ａ，１０３ｂ吸込み温度センサ、１０４ａ，１０４ｂ中央冷媒温度センサ、Ａ室内ユニットＡ，Ｂ室内ユニットＢ，Ｃ室外ユニット。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a so-called indoor multi-type air conditioner including a plurality of indoor units.
[0002]
[Prior art]
Conventionally, in an indoor multi-type air conditioner, if there is a pause indoor unit during heating, a part of the refrigerant flows into the pause indoor unit to radiate heat, so that there is a problem that the performance of the driving indoor unit is degraded.
In order to solve this problem, each indoor unit is provided with an electronic expansion valve, and the expansion valve of the paused indoor unit during heating is free from refrigerant accumulation due to the difference in the refrigerant inlet / outlet temperature of the heat exchanger in the indoor unit. The opening degree of the expansion valve is controlled to the minimum opening degree so as to flow only as little as possible, thereby preventing the performance of the operation-side indoor unit from deteriorating and the refrigerant pooling on the idle indoor unit side resulting in insufficient refrigerant I try to prevent such things.
[0003]
FIG. 10 is a refrigerant circuit diagram showing a configuration of the above-described conventional indoor multi-type air conditioner disclosed in, for example, Japanese Utility Model Laid-Open No. 62-43269.
In the figure, the air conditioner is composed of two indoor units A and B units, where 1 is a compressor, 2 is a four-way valve, 3 is a refrigerant pipe, 4a is an indoor heat exchanger of the A unit, 4b. the indoor heat exchanger B units, 5a, electronic expansion valve 5b is freely opening control using the microcomputer or the like, 6 refrigerant pipe, 9 outdoor heat exchanger, 13 Akyumure data, 11a, 11b is an indoor fan, 12 is an outdoor fan, and includes inlet and outlet refrigerant temperature sensors 101a, 101b, 102a, and 102b attached to the inlet and outlet pipes of the indoor heat exchangers 4a and 4b. Flows as indicated by solid arrows, and heating operation is performed, and cooling operations are performed by flowing as indicated by dotted arrows.
[0004]
In the refrigerant circuit configured as described above, when the A unit is operated during heating operation and the B unit is stopped and only one indoor unit is operated, the opening degree of the expansion valve 5b of the B unit is set to B The opening of the expansion valve 5b is adjusted so that the temperature difference becomes an appropriate temperature due to the difference in the refrigerant inlet / outlet temperature of the unit heat exchanger, that is, the refrigerant flows only as little as possible so that the refrigerant does not accumulate in the indoor exchanger 4b. I will decide.
The opening of the expansion valve at this time is determined when the detected temperatures of the refrigerant temperature sensors 101b and 102b attached to the inlet and outlet of the indoor heat exchanger 4b are T1 and T2, respectively, and the temperature difference (T1-T2). Is determined by determining the opening degree of the expansion valve 5b of the B unit on the pause side so that the temperature becomes an appropriate temperature, and the refrigerant flows as shown by solid line arrows in FIG.
[0005]
The expansion valves 5a and 5b are electronic expansion valves whose opening degree can be adjusted from 0 (fully closed) to 100 (fully open)%.
Now, when the heating operation is started, the refrigerant flows in the direction of the solid arrow shown in FIG. 10, passes through the four-way valve, the refrigerant pipes 3, 3a, 3b, is heat-exchanged and cooled by the indoor heat exchangers 4a, 4b, and then the liquid refrigerant. It becomes.
The liquid refrigerant is decompressed once by the expansion valves 5a and 5b, further decompressed by the expansion valve 7 through the refrigerant pipes 6a and 6b, and further heated by the outdoor heat exchanger 9 to become a gas refrigerant. The four-way valve 2, the accumulator Back through the data 13 to the compressor 1.
[0006]
Here, the control for determining the opening degree of the expansion valves 5a and 5b when the B unit, which is one indoor heat exchanger unit, is at rest will be described.
Warm tufts when the driver starts the controller 100 operation of the indoor heat exchanger unit confirms whether two or one, but two when each the expansion valve opening degree which is determined as the expansion valve 5a, opened 5b Indicate the degree.
[0007]
Next, assuming that the heating operation is one A unit, the A unit has a predetermined opening degree of the expansion valve 5a, but the opening degree of the expansion valve 5b of the B unit is once set to 0 (fully closed). However, after a short time has passed, the expansion valve 5b is opened slightly, and the temperature T1 of the refrigerant temperature sensor 101b of the inlet and outlet piping of the indoor heat exchanger 4b and the temperature T2 of 102b are detected and T1-T2 is calculated. Compared with the set value when the value is less than the amount of refrigerant accumulated in the heat exchanger, if the value is smaller than this set value, it is determined that the refrigerant is accumulated in the heat exchanger and the opening of the expansion valve 5b Is further opened, and the process is repeated until T1-T2 reaches the set value. That is, the opening degree of the expansion valve 5b is controlled so that the value of T1-T2 is maintained within the set temperature range.
[0008]
In the cooling operation, the refrigerant does not accumulate as in the heating operation. Therefore, if there is a pause unit, the pause-side expansion valve is simply closed.
Further, when both the A unit and the B unit are normally operated for heating, the opening degree of the expansion valves 5a and 5b is determined by the respective loads of the A and B units as is well known, and therefore this description is omitted.
[0009]
[Problems to be solved by the invention]
As described above, in the conventional indoor multi-type air conditioner, when there is a pause unit during heating, the inlet and outlet of the indoor heat exchanger are prevented in order to prevent refrigerant from being accumulated in the pause unit. The opening degree of the electronic expansion valve is controlled by the temperature difference of the refrigerant temperature sensor attached to the pipe.
[0010]
However, the refrigerant that is normally discharged from the compressor and flows into the indoor exchanger is in a superheated gas state. In order to set the opening of the expansion valve to an appropriate opening (minimum opening), the opening of the expansion valve is temporarily set to 0. (Fully closed) and the condensed liquid refrigerant must be temporarily stored in the indoor heat exchanger and the outlet piping of the indoor heat exchanger. If the opening degree can be controlled to an appropriate opening degree, the accumulated refrigerant can be recovered but initially In order to maintain normal operation at that time, a considerably large amount of refrigerant is required, and as a result, there is a problem that the amount of enclosed refrigerant must be increased.
[0011]
In addition, because the electronic expansion valve is controlled by the pipe temperature difference (refrigerant temperature difference) between the inlet and outlet of the indoor heat exchanger, the state of the refrigerant in the indoor heat exchanger when the opening is appropriate Is simply said that it has not reached the outlet of the indoor heat exchanger, and since the opening degree of the expansion valve is controlled from 0 (fully closed), the indoor There is a considerable amount of refrigerant accumulated in the exchanger, and in order to maintain normal air conditioner operation, it is necessary to set the amount of enclosed refrigerant in consideration of the amount of accumulated refrigerant. There was a problem that said the amount would increase.
[0012]
In addition, when the pause unit during heating performs a blowing operation, the expansion valve is controlled at the minimum opening and a small amount of refrigerant supplied from the compressor flows, and the refrigerant supplied from this compressor is usually It is superheated gas, condensed in the indoor heat exchanger and converted into liquid refrigerant and returned to the outdoor heat exchanger unit, but the heat released by the condensation at that time leads to an increase in the blowout temperature of the air blowing operation, and the inlet of the indoor heat exchanger The control of the expansion valve opening by the pipe temperature difference (refrigerant temperature difference) between the outlet and the outlet has a problem that it is impossible to grasp the degree of increase in the blowout temperature relative to the indoor suction temperature, and the rise in the blowout temperature must be allowed to occur. There was a problem that said.
[0013]
[Means for Solving the Problems]
The present invention has been made to solve the above-described problem. In an indoor multi-type air conditioner, an intake temperature sensor that detects an intake temperature of an indoor unit during heating operation, and an outlet or center of an indoor heat exchanger By including an outlet refrigerant temperature sensor that detects the refrigerant temperature, a central refrigerant temperature sensor, and an electronic expansion valve that controls the refrigerant flow rate, it is possible to determine whether or not the refrigerant has accumulated in the pause unit during heating operation. Detection is based on the temperature difference between the outlet refrigerant temperature or the central refrigerant temperature and the indoor suction temperature, and the opening of the electronic expansion valve is appropriately controlled in light of the result to prevent the refrigerant from accumulating in the indoor heat exchanger. , while suppressing the enclosed refrigerant amount, the temperature difference between quiescent and the outlet refrigerant temperature and the suction temperature of the heat exchanger of the set cylinder side indoor unit blowing state during the heating operation The expansion valve opening is changed, the degree of increase of the blowout temperature relative to the suction temperature is compared with a preset temperature setting value, and the adjustment of the expansion valve opening is repeated little by little so that it becomes smaller than the set temperature. The present invention provides an air conditioner that adjusts the blowing temperature by controlling the opening of an expansion valve .
[0014]
In the present invention according to the above means, when the air conditioner is in the heating operation and the heating operation unit and the pause unit coexist, the predetermined opening degree of the electronic expansion valve of the pause unit is very small close to 0% (fully closed). Then, the temperature difference between the outlet refrigerant temperature of the heat exchanger of the pause unit and the suction temperature of the pause unit is detected and compared with a preset value set in advance. Increase the opening of the electronic expansion valve by a certain amount.
[0015]
When this operation is periodically repeated and the temperature difference between the outlet refrigerant temperature of the heat exchanger of the pause unit and the suction temperature of the pause unit exceeds a predetermined set value, the opening degree of the electronic expansion valve becomes stable.
[0016]
By controlling the opening of the electronic expansion valve in this way, the amount of refrigerant accumulated in the indoor heat exchanger of the pause unit can be minimized by detecting the accumulation of refrigerant before accumulating in the indoor heat exchanger. It is possible to reduce the amount of refrigerant enclosed and to prevent a shortage of refrigerant due to the accumulation of the refrigerant.
[0017]
Further, when the pause unit is simply performing the air blowing operation, the blow-out temperature is detected from the central refrigerant temperature of the heat exchanger, and compared with a predetermined set value set in advance. Reduce the opening of the expansion valve by a certain amount. When this operation is periodically repeated and the temperature difference between the central refrigerant temperature of the heat exchanger of the pause unit and the suction temperature of the pause unit becomes a predetermined set value or less, the opening of the electronic expansion valve becomes stable. .
Thus, by controlling the opening degree of the electronic expansion valve, it is possible to suppress an increase in room temperature and improve comfort.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a system configuration diagram of an air conditioner according to a first embodiment. In the figure, the air conditioner is composed of an outdoor unit C and two units A and B.
Here, 1 is a compressor, 2 is a four-way valve, 3 is a refrigerant pipe, 4a is an indoor heat exchanger of unit A, 4b is an indoor heat exchanger of unit B, and 5a and 5b are freely available using a microcomputer or the like. Electronic expansion valve whose opening degree can be adjusted, 6 is a refrigerant pipe, 9 is an outdoor heat exchanger, 11a and 11b are indoor fans, 12 is an outdoor fan, 13 is an accumulator, 102a and 102b are indoor heat exchangers 4a and 4b Outlet refrigerant temperature sensors 103a and 103b attached to the outlet pipes, suction temperature sensors attached to portions where the intake air temperatures of the indoor units A and B can be detected, and 100 the outlet refrigerant temperature sensor 102a. , 102b, suction temperature sensors 103a, 103b, and controllers for controlling the electronic expansion valves 5a, 5b. The refrigerant is as indicated by solid arrows. The heating operation is performed by being.
[0019]
In the heating operation of the air conditioner configured as described above, when the indoor unit A is in the heating operation and the indoor unit B is in the inactive state, the indoor unit B as the inactive unit aims to make the temperature distribution in the indoor air-conditioned space uniform. The fan is running. In this state, the opening of the electronic expansion valve 5b of the indoor unit B that is a pause unit flows as little as possible so that the refrigerant does not accumulate in the indoor heat exchanger 4b or the like, that is, the refrigerant does not accumulate. Decide the opening so that there is no. A series of operations for determining the opening degree of the electronic expansion valve 5b in this case will be described below.
The electronic expansion valves 5a and 5b use expansion valves that can be controlled by a microcomputer or the like to adjust the opening from 0 (fully closed) to 100% (fully open). These electronic expansion valves 5a and 5b Is simply abbreviated as an expansion valve in the following description.
[0020]
First, when the heating operation is started, the refrigerant flows in the direction of the arrow shown in FIG. 1, passes through the four-way valve 2 and the refrigerant pipes 3, 3 a, 3 b, is heat-exchanged by the indoor heat exchangers 4 a, 4 b, and becomes liquid refrigerant, The pressure is reduced by the expansion valves 5 a and 5 b, is heated by the outdoor heat exchanger 9 through the refrigerant pipes 6 a, 6 b and 6, becomes a gas refrigerant, and returns to the compressor 1 through the four-way valve 2 and the accumulator 13.
[0021]
When the heating operation is started, the controller 100 confirms whether the indoor unit is operated by one or two units. If the unit B is inactive and only one unit A is in the heating operation, the operation-side indoor unit A is given. The opening degree of the expansion valve 5a is instructed so that the opening degree of the expansion valve corresponds to the load, and the opening degree of the expansion valve 5b of the indoor unit B on the pause side is set to a predetermined value described below.
[0022]
The expansion valve opening degree given to the indoor unit B which is a pause unit at this time will be described with reference to FIG.
FIG. 2 is a characteristic diagram showing the relationship between the expansion valve opening and the refrigerant flow rate given to the pause unit (however, the air blowing operation), the rising temperature of the blown air temperature with respect to the suction temperature, and the amount of refrigerant accumulated in the pause-side indoor heat exchanger. is there.
[0023]
According to FIG. 2, when the expansion valve opening given to the pause unit is 0% (fully closed), the refrigerant amount flowing to the pause unit and the temperature rise with respect to the discharge temperature are both 0, but the indoor heat exchanger The amount of refrigerant that accumulates is maximized. When the opening of the expansion valve is opened from 0% (fully closed), the amount of refrigerant that accumulates in the indoor heat exchanger decreases, but the refrigerant flow rate that flows to the pause unit increases, and the blowout temperature relative to the suction temperature The rise will also increase.
[0024]
In general, the increase in the amount of refrigerant that accumulates in the indoor heat exchanger with respect to the opening of the expansion valve and the increase in the blow-out temperature with respect to the suction temperature are in a contradictory relationship, and the most appropriate expansion including other given conditions Normally, the opening of the valve is selected, and there is an expansion valve opening of a pause unit that can be said to be appropriate in each air conditioner.
[0025]
FIG. 3 is a conceptual diagram showing the variation characteristic of the flow rate of the expansion valve.
In general, an expansion valve has a refrigerant flow rate deviation (flow rate variation) due to the influence of mechanical manufacturing errors and the influence of aging. Therefore, even if the expansion valve opening of an appropriate pause unit is determined from the relationship between the amount of refrigerant accumulated in the indoor heat exchanger shown in FIG. 2 and the degree of increase of the blowing temperature with respect to the suction temperature, as shown in FIG. Another problem arises that the expansion of the refrigerant flow rate does not always result in an appropriate expansion valve opening of the pause unit.
[0026]
Further, the opening degree of the expansion valve at which the flow rate becomes 0 is not necessarily 0%, and there are many expansion valves that have a characteristic that the flow rate of the refrigerant can be obtained when the opening degree reaches a certain degree. The expansion valve opening that becomes zero also deviates (expansion valve opening variation).
[0027]
From the above points, the expansion valve opening of the pause unit is usually set to a minute value that does not allow a large amount of refrigerant obtained from FIG. 2, that is, to be set lower than the appropriate expansion valve opening. .
However, if the expansion valve opening is set too low for the purpose of reducing the refrigerant flow rate at the same time, the flow rate becomes 0 due to the deviation of the expansion valve opening (variation of the expansion valve opening), and is accumulated in the indoor heat exchanger. There is a high possibility that the amount of refrigerant to be charged becomes large.
Also, if the expansion valve opening is set to a high value in order to avoid the flow rate of 0, the amount of refrigerant that accumulates in the indoor heat exchanger decreases, but the flow rate of the refrigerant increases and the degree of increase in the blow-out temperature relative to the suction temperature increases. End up.
[0028]
Accordingly, means for obtaining an appropriate expansion valve opening will be described below with reference to FIG.
FIG. 5 is a flowchart showing a procedure for determining the expansion valve opening. After setting the expansion valve opening of the suspension unit B to a predetermined opening, the compressor is operated, and the outlet is detected by the outlet refrigerant temperature sensor 102b of the indoor heat exchanger. The refrigerant temperature T2 is detected, and the suction temperature sensor 103b detects the suction temperature T1. Then, a temperature difference (T2-T1) between the outlet refrigerant temperature and the suction temperature is calculated, and the temperature difference (T2-T1) is compared with a preset value of a preset temperature. Since the refrigerant has accumulated in the valve, the opening of the expansion valve is corrected to be slightly opened.
[0029]
Next, the temperature difference (T2−T1) between the outlet refrigerant temperature and the suction temperature is calculated again, and this temperature difference (T2−T1) is compared with a preset temperature setting value. Correct the opening of the expansion valve so that it opens slightly. Thus, the expansion valve opening is adjusted little by little, and the process is repeated until the value of the temperature difference (T2-T1) between the outlet refrigerant temperature and the suction temperature becomes equal to or greater than the set value.
[0030]
Here, the set value of the temperature difference (T2-T1) will be described with reference to FIG.
Fig. 4 shows the operating characteristics with respect to changes in the opening of the expansion valve. When the pause unit is performing air blowing operation, the air volume is almost the same as in normal heating operation, and the heat exchange capacity of the indoor heat exchanger is heating. It is almost equal to driving.
In the case of the resting unit, the opening degree of the expansion valve is set to be extremely small as compared with the normal heating operation, and the refrigerant flow rate is very small. The indoor heat exchanger during heating cools the hot superheated gas flowing from the compressor and turns it into a liquid refrigerant. However, in the case of a sleep unit, the heat exchange capacity is almost the same as during heating operation (during heating operation). Refrigerant flow) >> (refrigerant flow rate at rest), the refrigerant of the rest unit cools much more than during normal heating.
[0031]
This relationship is closely related to the opening degree of the expansion valve that determines the refrigerant flow rate, and the refrigerant temperature decreases as the opening degree of the expansion valve decreases, and the suction temperature and the refrigerant temperature coincide with each other from a certain degree of opening. Using this characteristic, it is possible to determine the refrigerant flow rate and whether or not the refrigerant is flowing, and the temperature difference (T2−) between the outlet refrigerant temperature and the suction temperature of the heat exchanger for ensuring a substantially appropriate refrigerant flow rate. The optimum opening can be finally obtained by determining the range of the value of T1) and controlling the opening of the expansion valve.
[0032]
Therefore, by utilizing the correlation between the characteristics described above, an optimum value of the expansion valve opening is set, and the optimum value and the value of the temperature difference (T2-T1) between the outlet refrigerant temperature of the heat exchanger and the suction temperature are determined. In order to correct the expansion valve opening and make repeated adjustments to reach the optimal expansion valve opening, the variation in mechanical tolerance of the expansion valve and the deviation of the opening due to deterioration over time The influence can be eliminated.
In order to achieve the object in this embodiment, the outlet refrigerant temperature sensors 102a and 102b of the indoor heat exchanger may be installed in any part of the piping connecting the expansion valve and the indoor heat exchanger. is there.
[0033]
Embodiment 2. FIG.
In the first embodiment of the present invention, the opening degree of the expansion valve is determined by comparing the value of the temperature difference (T2-T1) between the outlet refrigerant temperature of the heat exchanger and the suction temperature. With this refrigerant circuit configuration, it is possible to control the air outlet temperature of the heating operation and heating pause unit. That is, the indoor heat exchanger 4a, 4b, the outlet refrigerant temperature sensor 102a of the indoor heat exchanger, 102b, and the indoor suction temperature sensor 103a, in 103b, the indoor suction temperature sensor 103a, the heat exchanger for the indoor suction temperature detected by 103b The outlet refrigerant temperature is detected by outlet refrigerant temperature sensors 102a and 102b, and the outlet temperature itself is controlled by the opening of the expansion valve based on the correlation between the increase in the outlet temperature with respect to the suction temperature and the outlet refrigerant temperature with respect to the outlet temperature. It becomes possible.
[0034]
FIGS. 6 and 7 show operating characteristics with respect to changes in the expansion valve opening for explaining the second embodiment. By increasing the expansion valve opening in FIG. The temperature rises, and as a result, (blowing temperature−suction temperature) increases. Using this characteristic, the expansion valve opening is changed as shown in the flowchart of the procedure for determining the expansion valve opening in FIG. 8 based on the temperature difference (T2−T1) between the outlet refrigerant temperature and the suction temperature of the heat exchanger. Compare the degree of increase of the blowing temperature with respect to the suction temperature and the preset temperature setting value, and adjust the opening degree of the expansion valve little by little so as to become smaller than the set temperature to control the opening degree of the expansion valve As a result, the blowout temperature can be adjusted, and as a result, an increase in the room temperature of the pause unit can be suppressed, leading to an improvement in comfort.
[0035]
Further, by utilizing the characteristics of the change in the outlet refrigerant temperature T2 and the outlet temperature of the heat exchanger when the expansion valve opening is changed as shown in FIG. It is also possible to control the blowing temperature by controlling with.
[0036]
Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 9 shows the refrigerant temperature in the center for detecting the refrigerant temperature in the indoor heat exchanger instead of the outlet refrigerant temperature sensors 102a and 102b in the indoor heat exchanger, compared to the refrigerant circuit in FIG. 1 used in the first embodiment. By attaching the sensors 104a and 104b, (the central refrigerant temperature of the indoor heat exchanger−the suction temperature) is detected, and this value is compared with a preset temperature, similar to the first and second embodiments described above. The appropriate opening degree of the expansion valve can be determined by controlling the opening degree of the expansion valve.
[0037]
【The invention's effect】
According to the present invention, in an air conditioner including a plurality of indoor units that can be individually operated and stopped, each of the indoor units includes an electronic expansion valve and an outlet refrigerant temperature that detects an outlet refrigerant temperature of the heat exchanger. Sensor, and a suction temperature sensor that detects the suction temperature, and detects the temperature difference between the outlet refrigerant temperature of the heat exchanger of the pause indoor unit and the suction temperature during heating operation, and this temperature difference is Compared with the set value of the set temperature, if the temperature is lower than the set temperature, correct the opening of the expansion valve slightly, and make adjustments repeatedly until the temperature difference value exceeds the set value. The electronic expansion valve is controlled to an appropriate opening degree so that there is no temperature difference between the outlet refrigerant temperature and the suction temperature of the heat exchanger of the pause-side indoor unit that is set to the paused and blowing state during the heating operation, Swelling Change the valve opening, compare the degree of rise of the blowout temperature with respect to the suction temperature and the preset temperature setting value, and gradually adjust the opening of the expansion valve so that it becomes smaller than the set temperature. The blow-off temperature is adjusted by controlling the opening degree. As a result, it is possible to minimize the amount of refrigerant accumulated in the indoor heat exchanger of the pause unit, and furthermore, the amount of refrigerant enclosed in the air conditioner is minimized and the operation is performed with insufficient refrigerant. Can also be prevented.
In addition, it is possible to always control the expansion valve so that the opening degree of the expansion valve is optimal even with respect to variations due to mechanical tolerances of the expansion valve and refrigerant flow deviation due to deterioration over time, and the influence can be eliminated. .
[0038]
In addition, the opening degree of the expansion valve is changed by the temperature difference between the outlet refrigerant temperature of the indoor heat exchanger or the central refrigerant temperature and the suction temperature with respect to the heating operation unit during heating of the indoor heat exchanger and the pause unit. By comparing the degree of increase of the temperature with respect to the suction temperature and a preset temperature set value, and adjusting the opening of the expansion valve little by little so as to be smaller than the set temperature, and controlling the opening of the expansion valve The blowout temperature can be adjusted, and as a result, an increase in the room temperature of the pause unit can be suppressed, and the comfort can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a system configuration of a first embodiment according to the present invention.
FIG. 2 is a diagram showing operating characteristics of the air conditioner with respect to a change in the expansion valve opening in the first embodiment according to the present invention.
FIG. 3 is an explanatory diagram showing a relational characteristic between an expansion valve opening change and a refrigerant flow rate in the first embodiment according to the present invention.
FIG. 4 is an explanatory diagram showing operating characteristics of the air conditioner with respect to a change in the expansion valve opening according to the first embodiment of the present invention.
FIG. 5 is a flowchart showing a procedure for determining an expansion valve opening degree in the first embodiment according to the present invention.
FIG. 6 is a diagram showing the operating characteristics of the air conditioner with respect to changes in the expansion valve opening in the second embodiment according to the present invention.
FIG. 7 is a diagram showing operating characteristics of an air conditioner with respect to a change in expansion valve opening degree in a second embodiment according to the present invention.
FIG. 8 is a flowchart showing a procedure for determining an expansion valve opening degree in a second embodiment according to the present invention.
FIG. 9 is a diagram showing a system configuration of a third embodiment according to the present invention.
FIG. 10 is a diagram showing a system configuration of a conventional air conditioner.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Compressor, 2 Four way valve, 3, 3a, 3b Refrigerant piping, 4a, 4b Indoor heat exchanger, 5a, 5b Electronic expansion valve, 6, 6a, 6b Refrigerant piping, 9 Outdoor heat exchanger, 11a, 11b Indoor blower, 12 outdoor blower, 100 controller, 102a, 102b outlet refrigerant temperature sensor, 103a, 103b suction temperature sensor, 104a, 104b central coolant temperature sensor, A indoor units A, B indoor unit B, C outdoor unit.

Claims

In an air conditioner having a plurality of indoor units that can be individually operated and stopped, each of the indoor units has an electronic expansion valve, an outlet refrigerant temperature sensor that detects an outlet refrigerant temperature of the heat exchanger, and an intake temperature. A suction temperature sensor that detects the temperature difference between the refrigerant temperature at the outlet of the heat exchanger of the pause-side indoor unit and the suction temperature during heating operation, and this temperature difference is set to a preset temperature. If the temperature is smaller than the set temperature, the expansion valve opening is corrected to be slightly opened, and the adjustment is repeated until the temperature difference value is equal to or greater than the set value, so that the refrigerant does not accumulate. While controlling the expansion valve to an appropriate opening degree , the expansion valve opening degree is changed depending on the temperature difference between the outlet refrigerant temperature and the suction temperature of the heat exchanger of the dormant indoor unit that is set to the paused and blowing state during heating operation. Let Compare the degree of increase of the blow-out temperature with respect to the suction temperature and a preset temperature set value, and adjust the opening of the expansion valve little by little so as to be smaller than the set temperature, thereby controlling the opening of the expansion valve The air conditioner characterized by adjusting the blowing temperature by means of the above.

In an air conditioner having a plurality of indoor units that can be individually operated and stopped, each of the indoor units has an electronic expansion valve, a central refrigerant temperature sensor that detects a central refrigerant temperature of the heat exchanger, and a suction temperature. A suction temperature sensor that detects the temperature difference between the central refrigerant temperature of the heat exchanger of the pause side indoor unit and the suction temperature during heating operation, and this temperature difference is set to a preset temperature. If the temperature is smaller than the set temperature, the expansion valve opening is corrected to be slightly opened, and the adjustment is repeated until the temperature difference value is equal to or greater than the set value, so that the refrigerant does not accumulate. While controlling the expansion valve to an appropriate opening degree , the expansion valve opening degree is changed depending on the temperature difference between the central refrigerant temperature and the suction temperature of the heat exchanger of the pause-side indoor unit that is set to the paused and blown state during heating operation Let Compare the degree of increase of the blow-out temperature with respect to the suction temperature and a preset temperature set value, and adjust the opening of the expansion valve little by little so as to be smaller than the set temperature, thereby controlling the opening of the expansion valve The air conditioner characterized by adjusting the blowing temperature by means of the above.