JP3835310B2

JP3835310B2 - Air conditioner

Info

Publication number: JP3835310B2
Application number: JP2002056717A
Authority: JP
Inventors: 弘篠崎; 実小林; 達也樋爪; 智暢渡辺; 伸至武内
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2002-03-04
Filing date: 2002-03-04
Publication date: 2006-10-18
Anticipated expiration: 2022-03-04
Also published as: JP2003254588A

Description

【０００１】
【発明の属する技術分野】
この発明は１台の室外機に対し複数の室内機を並列に接続して構成するマルチ式空気調和機に関するものである。
【０００２】
【従来の技術】
近年のマルチ式空気調和機においては各々の室内機に対応づけられた電動膨張弁を液側配管上にのみ設けて、ガス側配管上から電磁弁または電動膨張弁を削除した安価な冷媒回路で空調を行うものが増えてきている。一例を図５に示す。
【０００３】
この例では２台の室内機が１台の室外機に接続されており、Ａが室内機Ａ、Ｂが室内機Ｂ、Ｃが室外機を示す。２台の室内機はガス側配管（１０ａ、１０ｂ）と液側配管（１１ａ、１１ｂ）により接続されており、各々、室内熱交換器（４ａ、４ｂ）と室内ファン（５ａ、５ｂ）を備えている。一方、室外機には圧縮機（１）、四方弁（２）、室外熱交換器（８）、室外ファン（９）が設けられており、室外機内の液側配管上には各々の室内機に対応した電動膨張弁（７ａ、７ｂ）が設けられている。また冷媒は暖房運転時に実線矢印方向に流れる。
【０００４】
このマルチ式空気調和機で室内機Ａ、Ｂを同時に暖房運転する場合には、空調負荷に応じて室内機Ａ用の電動膨張弁と室内機Ｂ用の電動膨張弁を各々個別に制御し室内機Ａおよび室内機Ｂの熱交換器に対して冷媒を適正量分配することで、冷媒回路を効率良く動作させることができる。また、室内機Ａ側の暖房運転を継続し、室内機Ｂ側を停止した場合には、室内機Ｂ用の電動膨張弁を全閉にすることで室内機Ｂ側への冷媒通路を閉鎖し、暖房運転している室内機Ａと室外機間でクローズされた冷媒回路を構成することができる。
【０００５】
しかしながら、この冷媒回路はガス側配管に各々の室内機に対応した冷媒進入防止用の弁を備えていないために、高圧ガス冷媒が室内機Ｂの室内熱交換器に進入しここで放熱後、凝縮してしまう。このため、室内機Ｂ用の電動膨張弁を長時間に亘り全閉していると、室内機Ｂの室内熱交換器と液側配管内に冷媒が滞留し冷媒回路内の全体の冷媒循環量が不足することで室内機Ａ側の暖房能力が著しく低下してしまう欠点を抱えていた。そこで、従来のマルチ式空気調和機では停止側の冷媒回路上にある電動膨張弁を所定開度で開放し冷媒を流通させる制御により滞留を防止して、この冷媒回路を動作させていた。
【０００６】
例えば、特開平８−１５９５９０号公報に示された発明では、暖房運転を開始する際に停止側の室内機に対応した電動膨張弁を所定の開度で開放しておき、その後運転側の電動膨張弁の開度に対応させて停止側の開度も変化させ、冷媒の滞留を防止している。
【０００７】
【発明が解決しようとする課題】
しかしながら、上記で説明した従来のマルチ式空気調和機では停止側の室内機から戻ってきた冷媒の過冷却度を考慮した制御がなされておらず、このために停止している室内機の周囲温度が変化した際、制御が追従しない問題があった。
【０００８】
本発明の目的は、停止側熱交換器に滞留する冷媒を少なくし、運転している室内機の暖房能力を十分引き出すことが可能な空気調和機を提供することにある。
【０００９】
【課題を解決するための手段】
上記目的は、各々個別に運転、停止できる複数の室内機と、液側配管に複数の室内機を接続するための液側配管接続バルブと、前記複数の室内機の夫々毎に設けられ冷媒流量を制御する電動膨張弁とを有する室外機と備えた空気調和機において、前記電動膨張弁と前記液側配管接続バルブとの間に設けられ冷媒温度を検知する温度センサーと、外気温度を検知する外気温度センサーとを備え、暖房運転時、前記温度センサーにより運転中の室内機と停止している室内機の冷媒温度を各々検知し、運転中の室内機からの冷媒温度と停止している室内機の冷媒温度との温度差が、前記外気温度センサー出力に基づいて演算した所定の温度差となるように前記電動膨張弁の開度を調整する制御手段を備えることにより達成される。
【００１０】
上記のマルチ式空気調和機は停止中の室内機が含まれた暖房運転を開始する際、運転側の電動膨張弁を運転用初期開度に、停止側の電動膨張弁を停止用初期開度に絞り込み、次いで定期的に運転側の過冷却冷媒温度と停止側の過冷却冷媒温度を検知して、この温度差が外気温度から演算する所定の温度差になるよう各々の電動膨張弁を制御する。この操作を繰り返すことで運転側の過冷却冷媒温度と停止側の過冷却冷媒温度を所定の温度差に維持し、停止側の室内熱交換器と液側接続配管における冷媒の滞留を防止することした。この制御手段により運転している室内機の暖房能力を十分に引き出す作用を奏する。
【００１１】
【発明の実施の形態】
以下、この発明の実施形態を図１と図２を用いて説明する。
【００１２】
図１はこの発明の実施の形態におけるマルチ式空気調和機の冷媒回路構成図である。図の空気調和機は２台の室内機が１台の室外機に接続されており、Ａが室内機Ａ、Ｂが室内機Ｂ、Ｃが室外機を示す。２台の室内機はガス側配管（１０ａ、１０ｂ）上に設けられたガス側配管接続バルブ（３ａ、３ｂ）と液側配管（１１ａ、１１ｂ）上に設けられた液側配管接続バルブ（６ａ、６ｂ）により接続されており、各々の室内機には室内熱交換器（４ａ、４ｂ）、室内ファン（５ａ、５ｂ）と室温センサー（３２ａ、３２ｂ）が設けられている。一方、室外機には圧縮機（１）、四方弁（２）、室外熱交換器（８）、室外ファン（９）と外気温度センサー（２４）、液側配管上に各々の室内機に対応した電動膨張弁（７ａ、７ｂ）が設けられている。また冷媒回路の主要な冷媒温度を検知するために圧縮機近傍の配管に冷媒吐出温度センサー（２２）を、電動膨張弁と液側配管接続バルブ間の配管には過冷却冷媒温度センサー（２３ａ、２３ｂ）を設けている。
【００１３】
図２はこの発明の実施の形態におけるマルチ式空気調和機の制御ブロック図を示す。図で２１が室外機に設けられた室外制御装置、３１ａが室内機Ａの室内制御装置、３１ｂが室内機Ｂの室内制御装置を示す。２つの室内制御装置は制御信号の送受信を行うためのデータ伝送線（５１ａ、５１ｂ）により室外制御装置と接続されており、各々の室内制御装置には現在の室温を検知するための前記、室温センサーと、室内機の能力クラス、室内熱交換器の容積クラス等の補正パラメータを記憶している記憶装置（３３ａ、３３ｂ）が接続されている。一方、室外制御装置には圧縮機から吐出した冷媒の温度を検知するための前記、冷媒吐出温度センサーと、過冷却冷媒温度を検知するための前記、過冷却冷媒温度センサーが接続されている。さらに室外機制御装置内部には図２の制御ブロック図には明示していないが圧縮機回転数検出手段と圧縮機回転数制御手段と電動膨張弁制御手段が設けられており、この制御手段により圧縮機と各電動膨張弁を制御している。
【００１４】
このように構成したマルチ式空気調和機で室内機Ａと室内機Ｂを共に暖房運転した場合の動作について以下に説明する。暖房運転が開始されると各室内制御装置はリモコンから受けた設定風速に従い室内ファンを制御するとともに、暖房運転開始指令および空調負荷等の制御情報を室外制御装置に送信する。これらの情報はリモコンにより設定された設定温度と室温センサーから検知した室温をもとに演算している。
【００１５】
室外制御装置は室内機Ａ、および室内機Ｂから暖房運転の開始指令を受けると四方弁を暖房サイクル側に切換え、室外ファンを所定の回転数で駆動し、各室内機の補正パラメータにあわせて、各々の電動膨張弁を所定の運転用初期開度に絞込む。さらに、室内機Ａ、および室内機Ｂから受信した圧縮機の回転数指令値をもとに２台運転に必要な圧縮機回転数を演算により求めて圧縮機を駆動する。その後、室外制御装置は圧縮機回転数検出手段（詳細な説明は省略）により検知した実際の回転数（以下、圧縮機実回転数と称す）と上記演算により求めた回転数目標値とを比較しながら高精度な圧縮機回転数制御（詳細な説明は省略）を行っている。
【００１６】
上記制御装置の働きにより冷媒回路内の冷媒は図１に示す矢印の方向に流れる。始めに圧縮機で加圧された冷媒は過熱蒸気として四方弁を通過して各室内熱交換器に流れ込み、室内ファンにより送られた空気に放熱することで過冷却冷媒となる。その後、各電動膨張弁を通過することで減圧され、室外熱交換器で室外ファンにより送られた空気により加熱されて、四方弁を経由し圧縮機に戻る。
【００１７】
次に上記の冷媒回路において冷媒循環量と冷媒温度を調整している電動膨張弁の開閉動作について図３により説明する。図３は室外制御装置に設けた電動膨張弁制御手段のフローチャートである。電動膨張弁制御手段は冷媒吐出温度補正制御、圧縮機回転数偏差補正制御、分配制御、開閉制御から構成されており、冷媒吐出温度センサーにより検知した冷媒吐出温度と圧縮機回転数検出手段により検知した圧縮機実回転数と過冷却冷媒温度センサーにより検知した過冷却冷媒温度と外気温度センサーにより検知した外気温度をもとに、各電動膨張弁の弁開度を制御している。ここで電動膨張弁制御手段について以下説明する。
【００１８】
まず、冷媒吐出温度補正制御（Ｓ１）では圧縮機により加圧された冷媒の温度、すなわち冷媒吐出温度が圧縮機回転数に対応した所定の温度となるよう電動膨張弁の開度を補正するための演算を行っている。この演算には冷媒吐出温度補正用のファジー演算が用いられており、この演算に冷媒吐出温度と圧縮機実回転数を代入すると電動膨張弁の補正開度を符号付きで求めることができる。ここでの演算結果を以下、冷媒吐出温度補正開度と称する。
【００１９】
圧縮機回転数偏差補正制御（Ｓ２）では冷媒回路の負荷変動により圧縮機の回転数が変動した場合の補正開度を求めている。この演算には圧縮機実回転数を代入し所定定数を掛け合わせ、補正係数を加算することで、符号付き補正開度を求めている。ここでの演算結果を以下、圧縮機回転数変動補正開度と称する。
【００２０】
次いで分配制御（Ｓ３）では室内機の運転台数を検知して２台運転中の処理と１台運転中の処理に分けて演算を行っており、２台運転中の演算は各室内機に適正な冷媒循環量を供給するための分配制御として行っている。２台運転中の分配制御は室外機Ａの過冷却冷媒温度と室外機Ｂの過冷却冷媒温度が同一温度となるよう各電動膨張弁の補正開度を演算するものであり、現在の温度差(Ｔsc)を分配制御用のファジー演算に代入して補正開度を符号付きで求めている。ここで求められた結果を以下、過冷却冷媒温度補正開度と称する。
【００２１】
最後にステップ４では各電動膨張弁の現在開度に対して前記３つの補正開度を総計し目標開度を求め、各々の電動膨張弁を目標開度に合わせて開閉している。
【００２２】
この電動膨張弁の制御を所定周期ごとに実施し、２台運転における冷媒回路内の冷媒循環量と冷媒温度を継続的に最適な状態に維持している。
【００２３】
次ぎに、暖房運転において室内機Ａを運転し室内機Ｂを停止させた場合の１台運転について、図１と図２と図３と図４を用いて説明する。室外制御装置はデータ伝送線上の暖房運転開始指令により室内機Ａの１台だけが暖房運転を開始したと確認すると、四方弁を暖房サイクル側に切換え、室外ファンを所定の回転数で駆動して、室内機Ａの電動膨張弁を所定の運転用初期開度に、また室内機Ｂの電動膨張弁を所定の停止用初期開度に絞込む。さらに、室外制御装置は室内機Ａから受信した圧縮機の指令回転数をもとに１台運転に必要な圧縮機回転数を求めて圧縮機を駆動する。その後、停止している室内機Ｂへの冷媒滞留を防止し、冷媒回路全体の冷媒循環量と冷媒温度を継続的に最適な状態に維持するために、電動膨張弁制御手段により各々の電動膨張弁を所定の開度に制御する。
【００２４】
１台運転における電動膨張弁の開閉動作について説明する。各々の電動膨張弁開度は２台運転時と同様、電動膨張弁制御手段によって補正を行っている。しかしながら、１台運転時の分配制御については運転している室内機の空調負荷と停止している室内機の熱漏洩量を考慮して補正開度を求める必要があるため、２台運転時と同じ演算で単純に補正開度を求めることができない。そこで、室外制御装置に記憶しているパラメータと外気温度をもとに、運転している室内機の空調負荷と停止している室内機の熱漏洩量を判断し、運転側と停止側の過冷却冷媒に所定の温度差がつくように分配制御を実施している。
【００２５】
１台運転における分配制御は、始めに図３のステップＳ３１において、室外制御装置に記憶しているパラメータと外気温度により温度差補正定数（Ｋso）を演算により求める。図４は温度差補正定数であり、外気温度が低い場合の熱漏洩を補正するものであり、外気温度が低い場合の温度差は、高い場合よりも低くなる方向に設定することにより、低温時の停止側配管温度低下による停止側冷媒循環量の増加を押さえ適正な冷媒循環量を得ることを目的とする。次に図３のステップＳ３２で、現在の温度差を演算する時に温度差補正定数（Ｋso）を加算することで行う。その結果を分配制御用のファジー演算に代入し補正開度を符号付きで求める。また、上記のステップＳ３１では温度差補正定数を符号付きで求めることで、室内機Ａ、室内機Ｂのいづれかが１台運転を行っても、場合分けせずにステップＳ３２の演算式を利用可能にしている。
【００２６】
この電動膨張弁の制御を所定周期ごとに実施することで、１台運転における停止側の室内熱交換器と液側接続配管における冷媒の滞留を防止し、冷媒回路内の冷媒循環量と冷媒温度を継続的に最適な状態に維持している。
【００２７】
以上、２台の室内機を１台の室外機に接続したマルチ式空気調和機における本発明の実施例を説明してきたが、３台以上の室内機を１台の室外機に接続したマルチ式空気調和機においても本発明を適用することが可能である。
【００２８】
３台以上の室内機を１台の室外機に接続したマルチ式空気調和機で、全ての室内機を暖房運転した場合には各々の室内機に対応した過冷却冷媒温度センサーから最高温度と最低温度を検知して、この温度差を同一温度とするよう電動膨張弁を制御することで各々の室内機における冷媒回路内の冷媒循環量と冷媒温度を継続的に最適な状態に維持することが可能である。
【００２９】
さらに、停止している室内機を含む暖房運転を実施した場合には運転側の過冷却冷媒温度の平均値と停止側の過冷却冷媒温度の平均値を求め、この温度差が所定の温度差となるように制御することで、停止している室内熱交換器と液側接続配管における冷媒の滞留を防止し、冷媒回路内の冷媒循環量と冷媒温度を継続的に最適な状態に維持することが可能である。
【００３０】
【発明の効果】
この発明によれば、複数台の室内機を１台の室外機に接続して構成されたマルチ式空気調和機において、停止している室内機が含まれた暖房運転を行う際、運転している室内機側の過冷却冷媒温度と停止している室内機側の過冷却冷媒温度を検知して、外気温度から演算した所定の温度差となるよう電動膨張弁を制御することで、室温や外気温度等の空調負荷要因に影響を受けずに停止側の室内熱交換器と液側接続配管における冷媒の滞留を防止し、運転している室内機の暖房能力を十分に引き出すことができる。
【図面の簡単な説明】
【図１】この発明の実施の形態におけるマルチ式空気調和機の冷媒回路構成図。
【図２】この発明の実施の形態における空気調和機の制御ブロック図。
【図３】この発明の電動膨張弁の制御論理をフローチャートで示した図。
【図４】外気温度と温度差外気温度補正定数のグラフ図。
【図５】従来のマルチ式空気調和機の冷媒回路構成図。
【符号の説明】
Ａ…室内機Ａ、Ｂ…室内機Ｂ、Ｃ…室外機、１…圧縮機、２…四方弁、３ａ、３ｂ…ガス側配管接続バルブ、４ａ、４ｂ…室内熱交換器、５ａ、５ｂ…室内ファン、６ａ、６ｂ…液側配管接続バルブ、７ａ、７ｂ…電動膨張弁、８…室外熱交換器、９…室外ファン、１０ａ、１０ｂ…ガス側配管、１１ａ、１１ｂ…液側配管、２１…室外制御装置、２２…冷媒吐出温度センサー、２３ａ、２３ｂ…過冷却冷媒温度センサー、２４…外気温度センサー、３１ａ、３１ｂ…室内制御装置、３２ａ、３２ｂ…室温センサー、３３ａ、３３ｂ…記憶装置、４１ａ、４１ｂ…リモコン、５１ａ、５１ｂ…データ伝送線。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-type air conditioner configured by connecting a plurality of indoor units in parallel to one outdoor unit.
[0002]
[Prior art]
In recent multi-type air conditioners, an electric expansion valve associated with each indoor unit is provided only on the liquid side pipe, and an inexpensive refrigerant circuit in which the electromagnetic valve or the electric expansion valve is omitted from the gas side pipe. The number of air conditioning is increasing. An example is shown in FIG.
[0003]
In this example, two indoor units are connected to one outdoor unit, A is an indoor unit A, B is an indoor unit B, and C is an outdoor unit. The two indoor units are connected by gas side pipes (10a, 10b) and liquid side pipes (11a, 11b), and each include an indoor heat exchanger (4a, 4b) and an indoor fan (5a, 5b). ing. On the other hand, the outdoor unit is provided with a compressor (1), a four-way valve (2), an outdoor heat exchanger (8), and an outdoor fan (9), and each indoor unit is placed on a liquid side pipe in the outdoor unit. Electric expansion valves (7a, 7b) corresponding to the above are provided. The refrigerant flows in the direction of the solid arrow during the heating operation.
[0004]
In the case where the indoor units A and B are simultaneously heated with this multi-type air conditioner, the electric expansion valve for the indoor unit A and the electric expansion valve for the indoor unit B are individually controlled according to the air conditioning load. By distributing an appropriate amount of refrigerant to the heat exchangers of the machine A and the indoor unit B, the refrigerant circuit can be operated efficiently. Further, when the heating operation on the indoor unit A side is continued and the indoor unit B side is stopped, the refrigerant passage to the indoor unit B side is closed by fully closing the electric expansion valve for the indoor unit B. A closed refrigerant circuit can be configured between the indoor unit A and the outdoor unit that are performing heating operation.
[0005]
However, since this refrigerant circuit is not provided with a refrigerant entry prevention valve corresponding to each indoor unit in the gas side pipe, the high-pressure gas refrigerant enters the indoor heat exchanger of the indoor unit B and radiates heat here. It will condense. For this reason, when the electric expansion valve for the indoor unit B is fully closed for a long time, the refrigerant stays in the indoor heat exchanger and the liquid side pipe of the indoor unit B, and the entire refrigerant circulation amount in the refrigerant circuit As a result, the heating capacity on the indoor unit A side is significantly reduced. Therefore, in a conventional multi-type air conditioner, the electric expansion valve on the refrigerant circuit on the stop side is opened at a predetermined opening to prevent stagnation and control the refrigerant circuit to operate.
[0006]
For example, in the invention disclosed in Japanese Patent Application Laid-Open No. 8-159590, when the heating operation is started, the electric expansion valve corresponding to the indoor unit on the stop side is opened at a predetermined opening, and then the electric motor on the operation side is opened. Corresponding to the opening of the expansion valve, the opening on the stop side is also changed to prevent the refrigerant from staying.
[0007]
[Problems to be solved by the invention]
However, in the conventional multi-type air conditioner described above, the control is not performed in consideration of the degree of supercooling of the refrigerant returned from the indoor unit on the stop side, and therefore the ambient temperature of the stopped indoor unit There was a problem that the control did not follow when changed.
[0008]
An object of the present invention is to provide an air conditioner that can reduce the amount of refrigerant accumulated in a stop-side heat exchanger and sufficiently extract the heating capacity of an operating indoor unit.
[0009]
[Means for Solving the Problems]
The above-mentioned objects are provided for each of the plurality of indoor units that can be individually operated and stopped, the liquid side pipe connection valve for connecting the plurality of indoor units to the liquid side pipe, and the plurality of indoor units. In an air conditioner including an outdoor unit having an electric expansion valve that controls the temperature, a temperature sensor that is provided between the electric expansion valve and the liquid side pipe connection valve and detects a refrigerant temperature, and detects an outside air temperature An outdoor air temperature sensor, and during the heating operation, the temperature sensor detects the refrigerant temperature of the operating indoor unit and the stopped indoor unit, respectively, and the temperature of the refrigerant from the operating indoor unit and the stopped indoor unit are detected. This is achieved by providing control means for adjusting the opening degree of the electric expansion valve so that the temperature difference from the refrigerant temperature of the machine becomes a predetermined temperature difference calculated based on the output of the outside air temperature sensor.
[0010]
When the above-described multi-type air conditioner starts a heating operation including a stopped indoor unit, the electric expansion valve on the operation side is set to the initial opening degree for operation, and the electric opening valve on the stop side is set to the initial opening degree for stoppage. Next, periodically detect the supercooling refrigerant temperature on the operation side and the subcooling refrigerant temperature on the stop side, and control each electric expansion valve so that this temperature difference becomes a predetermined temperature difference calculated from the outside air temperature To do. By repeating this operation, the operation-side supercooling refrigerant temperature and the stop-side supercooling refrigerant temperature are maintained at a predetermined temperature difference to prevent the refrigerant from staying in the stop-side indoor heat exchanger and the liquid-side connection pipe. did. There is an effect that the heating capacity of the indoor unit operated by this control means is sufficiently extracted.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS.
[0012]
FIG. 1 is a refrigerant circuit configuration diagram of a multi-type air conditioner according to an embodiment of the present invention. In the illustrated air conditioner, two indoor units are connected to one outdoor unit, A is an indoor unit A, B is an indoor unit B, and C is an outdoor unit. The two indoor units have gas side pipe connection valves (3a, 3b) provided on the gas side pipes (10a, 10b) and liquid side pipe connection valves (6a) provided on the liquid side pipes (11a, 11b). 6b), and each indoor unit is provided with indoor heat exchangers (4a, 4b), indoor fans (5a, 5b) and room temperature sensors (32a, 32b). On the other hand, the outdoor unit corresponds to each indoor unit on the compressor (1), four-way valve (2), outdoor heat exchanger (8), outdoor fan (9) and outdoor temperature sensor (24), and liquid side piping. The electrically operated expansion valves (7a, 7b) are provided. In order to detect the main refrigerant temperature of the refrigerant circuit, a refrigerant discharge temperature sensor (22) is provided in a pipe in the vicinity of the compressor, and a supercooled refrigerant temperature sensor (23a, 23) is provided in a pipe between the electric expansion valve and the liquid side pipe connection valve. 23b).
[0013]
FIG. 2 is a control block diagram of the multi-type air conditioner according to the embodiment of the present invention. In the figure, 21 is an outdoor control device provided in the outdoor unit, 31a is an indoor control device of the indoor unit A, and 31b is an indoor control device of the indoor unit B. The two indoor control devices are connected to the outdoor control device by data transmission lines (51a, 51b) for transmitting and receiving control signals, and each of the indoor control devices has the room temperature to detect the current room temperature. The sensor is connected to a storage device (33a, 33b) that stores correction parameters such as the capacity class of the indoor unit and the volume class of the indoor heat exchanger. On the other hand, the outdoor control device is connected to the refrigerant discharge temperature sensor for detecting the temperature of the refrigerant discharged from the compressor and the supercooling refrigerant temperature sensor for detecting the supercooling refrigerant temperature. Further, although not explicitly shown in the control block diagram of FIG. 2, the outdoor unit control device is provided with a compressor rotation speed detection means, a compressor rotation speed control means, and an electric expansion valve control means. The compressor and each electric expansion valve are controlled.
[0014]
The operation when the indoor unit A and the indoor unit B are both heated by the multi-type air conditioner configured as described above will be described below. When the heating operation is started, each indoor control device controls the indoor fan according to the set wind speed received from the remote controller, and transmits control information such as a heating operation start command and an air conditioning load to the outdoor control device. These pieces of information are calculated based on the set temperature set by the remote controller and the room temperature detected from the room temperature sensor.
[0015]
When the outdoor control device receives a heating operation start command from the indoor unit A and the indoor unit B, the outdoor control device switches the four-way valve to the heating cycle side, drives the outdoor fan at a predetermined rotational speed, and matches the correction parameters of each indoor unit. Each electric expansion valve is narrowed down to a predetermined initial opening for operation. Further, based on the compressor rotational speed command values received from the indoor unit A and the indoor unit B, the compressor rotational speed required for the operation of the two units is obtained by calculation to drive the compressor. After that, the outdoor control device compares the actual rotational speed detected by the compressor rotational speed detection means (detailed explanation is omitted) (hereinafter referred to as the actual compressor rotational speed) with the rotational speed target value obtained by the above calculation. However, highly accurate compressor rotation speed control (detailed explanation is omitted) is performed.
[0016]
The refrigerant in the refrigerant circuit flows in the direction of the arrow shown in FIG. First, the refrigerant pressurized by the compressor passes through the four-way valve as superheated steam and flows into each indoor heat exchanger, and becomes a supercooled refrigerant by dissipating heat to the air sent by the indoor fan. Thereafter, the pressure is reduced by passing through each electric expansion valve, heated by the air sent by the outdoor fan in the outdoor heat exchanger, and returned to the compressor via the four-way valve.
[0017]
Next, the opening / closing operation of the electric expansion valve adjusting the refrigerant circulation amount and the refrigerant temperature in the refrigerant circuit will be described with reference to FIG. FIG. 3 is a flowchart of the electric expansion valve control means provided in the outdoor control device. The electric expansion valve control means is composed of refrigerant discharge temperature correction control, compressor rotation speed deviation correction control, distribution control, and open / close control, and is detected by the refrigerant discharge temperature detected by the refrigerant discharge temperature sensor and the compressor rotation speed detection means. The valve opening degree of each electric expansion valve is controlled based on the actual number of rotations of the compressor, the supercooling refrigerant temperature detected by the supercooling refrigerant temperature sensor, and the outside air temperature detected by the outside air temperature sensor. Here, the electric expansion valve control means will be described below.
[0018]
First, in the refrigerant discharge temperature correction control (S1), in order to correct the opening of the electric expansion valve so that the temperature of the refrigerant pressurized by the compressor, that is, the refrigerant discharge temperature becomes a predetermined temperature corresponding to the compressor rotation speed. The operation is performed. For this calculation, fuzzy calculation for correcting the refrigerant discharge temperature is used. If the refrigerant discharge temperature and the actual compressor speed are substituted for this calculation, the correction opening degree of the electric expansion valve can be obtained with a sign. Hereinafter, the calculation result is referred to as a refrigerant discharge temperature correction opening degree.
[0019]
In the compressor rotational speed deviation correction control (S2), a corrected opening degree is obtained when the rotational speed of the compressor fluctuates due to load fluctuation of the refrigerant circuit. In this calculation, the actual rotation speed of the compressor is substituted, multiplied by a predetermined constant, and a correction coefficient is added to obtain a signed correction opening. Hereinafter, the calculation result is referred to as a compressor rotation speed fluctuation correction opening.
[0020]
Next, in the distribution control (S3), the number of indoor units operated is detected, and calculation is performed separately for processing during operation of two units and processing during operation of one unit. Calculations during operation of two units are appropriate for each indoor unit. This is performed as distribution control for supplying a sufficient amount of refrigerant circulation. The distribution control during the operation of the two units is to calculate the correction opening degree of each electric expansion valve so that the supercooling refrigerant temperature of the outdoor unit A and the supercooling refrigerant temperature of the outdoor unit B become the same temperature, and the current temperature difference Substituting (Tsc) into the fuzzy calculation for distribution control, the corrected opening is obtained with a sign. The result obtained here is hereinafter referred to as a supercooled refrigerant temperature correction opening.
[0021]
Finally, in step 4, the three corrected openings are summed with respect to the current opening of each electric expansion valve to obtain a target opening, and each electric expansion valve is opened and closed in accordance with the target opening.
[0022]
The electric expansion valve is controlled at predetermined intervals, and the refrigerant circulation amount and the refrigerant temperature in the refrigerant circuit in the two-unit operation are continuously maintained in an optimum state.
[0023]
Next, single operation when the indoor unit A is operated and the indoor unit B is stopped in the heating operation will be described with reference to FIGS. 1, 2, 3, and 4. When the outdoor control device confirms that only one of the indoor units A has started the heating operation by the heating operation start command on the data transmission line, it switches the four-way valve to the heating cycle side and drives the outdoor fan at a predetermined rotation speed. Then, the electric expansion valve of the indoor unit A is narrowed to a predetermined initial opening for operation, and the electric expansion valve of the indoor unit B is narrowed to a predetermined initial opening for stopping. Further, the outdoor control device determines the compressor rotational speed necessary for the single unit operation based on the command rotational speed of the compressor received from the indoor unit A, and drives the compressor. Thereafter, in order to prevent the refrigerant from staying in the stopped indoor unit B and maintain the refrigerant circulation amount and the refrigerant temperature in the entire refrigerant circuit continuously in an optimal state, each electric expansion valve control means controls each electric expansion. The valve is controlled to a predetermined opening.
[0024]
The opening / closing operation of the electric expansion valve in single-unit operation will be described. Each electric expansion valve opening is corrected by the electric expansion valve control means as in the case of operating two units. However, since it is necessary to calculate the correction opening in consideration of the air conditioning load of the operating indoor unit and the amount of heat leakage of the stopped indoor unit for the distribution control during single unit operation, The corrected opening cannot simply be obtained with the same calculation. Therefore, based on the parameters stored in the outdoor control device and the outside air temperature, the air conditioning load of the operating indoor unit and the amount of heat leakage of the stopped indoor unit are judged, and the operating side and the Distribution control is performed so that the cooling refrigerant has a predetermined temperature difference.
[0025]
In the distribution control in the single unit operation, first, in step S31 of FIG. 3, a temperature difference correction constant (Kso) is obtained by calculation based on the parameters stored in the outdoor control device and the outside air temperature. FIG. 4 shows temperature difference correction constants for correcting heat leakage when the outside air temperature is low. By setting the temperature difference when the outside air temperature is low to be lower than when it is high, An object of the present invention is to obtain an appropriate refrigerant circulation amount by suppressing an increase in the stop side refrigerant circulation amount due to a decrease in the stop side pipe temperature. Next, in step S32 of FIG. 3, the temperature difference correction constant (Kso) is added when calculating the current temperature difference. The result is substituted into fuzzy calculation for distribution control, and the corrected opening is obtained with a sign. Further, by calculating the temperature difference correction constant with a sign in the above step S31, even if any one of the indoor unit A and the indoor unit B is operated, the calculation formula of step S32 can be used without dividing the case. I have to.
[0026]
By performing this control of the electric expansion valve at predetermined intervals, it is possible to prevent the refrigerant from staying in the indoor heat exchanger on the stop side and the liquid connection pipe in the single unit operation, and the refrigerant circulation amount and the refrigerant temperature in the refrigerant circuit. Is continuously maintained in an optimal state.
[0027]
As mentioned above, although the Example of this invention in the multi-type air conditioner which connected two indoor units to one outdoor unit was described, the multi type which connected three or more indoor units to one outdoor unit The present invention can also be applied to an air conditioner.
[0028]
In a multi-type air conditioner in which three or more indoor units are connected to one outdoor unit. When all indoor units are heated, the maximum and minimum temperatures are determined from the supercooled refrigerant temperature sensor corresponding to each indoor unit. By detecting the temperature and controlling the electric expansion valve so that this temperature difference is the same temperature, the refrigerant circulation amount and the refrigerant temperature in the refrigerant circuit in each indoor unit can be continuously maintained in an optimum state. Is possible.
[0029]
Further, when the heating operation including the stopped indoor unit is performed, the average value of the supercooling refrigerant temperature on the operation side and the average value of the supercooling refrigerant temperature on the stop side are obtained, and this temperature difference is a predetermined temperature difference. The refrigerant is prevented from staying in the stopped indoor heat exchanger and the liquid side connection pipe, and the refrigerant circulation amount and the refrigerant temperature in the refrigerant circuit are continuously maintained in the optimum state. It is possible.
[0030]
【The invention's effect】
According to the present invention, in a multi-type air conditioner configured by connecting a plurality of indoor units to a single outdoor unit, when performing a heating operation including a stopped indoor unit, By detecting the temperature of the subcooling refrigerant on the indoor unit side and the temperature of the subcooling refrigerant on the stopped indoor unit side, and controlling the electric expansion valve so as to obtain a predetermined temperature difference calculated from the outside air temperature, Without being affected by air-conditioning load factors such as the outside air temperature, it is possible to prevent the refrigerant from staying in the indoor heat exchanger on the stop side and the liquid side connection pipe, and to sufficiently draw out the heating capacity of the operating indoor unit.
[Brief description of the drawings]
FIG. 1 is a refrigerant circuit configuration diagram of a multi-type air conditioner according to an embodiment of the present invention.
FIG. 2 is a control block diagram of the air conditioner according to the embodiment of the present invention.
FIG. 3 is a flowchart showing the control logic of the electric expansion valve according to the present invention.
FIG. 4 is a graph of an outside air temperature and a temperature difference outside air temperature correction constant.
FIG. 5 is a refrigerant circuit configuration diagram of a conventional multi-type air conditioner.
[Explanation of symbols]
A ... Indoor unit A, B ... Indoor unit B, C ... Outdoor unit, 1 ... Compressor, 2 ... Four-way valve, 3a, 3b ... Gas side pipe connection valve, 4a, 4b ... Indoor heat exchanger, 5a, 5b ... Indoor fan, 6a, 6b ... Liquid side pipe connection valve, 7a, 7b ... Electric expansion valve, 8 ... Outdoor heat exchanger, 9 ... Outdoor fan, 10a, 10b ... Gas side pipe, 11a, 11b ... Liquid side pipe, 21 ... outdoor control device, 22 ... refrigerant discharge temperature sensor, 23a, 23b ... supercooling refrigerant temperature sensor, 24 ... outside air temperature sensor, 31a, 31b ... indoor control device, 32a, 32b ... room temperature sensor, 33a, 33b ... storage device, 41a, 41b ... remote control, 51a, 51b ... data transmission line.

Claims

Each individually operated, control a plurality of indoor units can be stopped, and the liquid-side pipe connection valves for connecting a plurality of indoor units in the liquid-side piping, the refrigerant flow rate is provided for each respective of said plurality of indoor units In an air conditioner equipped with an outdoor unit having an electric expansion valve to be controlled,
A temperature sensor for detecting the refrigerant temperature provided between the front Symbol electrostatic dynamic expansion valve and before Symbol liquid side pipe connection valves, e Bei the outside air temperature sensor for detecting the outside air temperature, during the heating operation, before Symbol temperature each detecting the refrigerant temperature of the indoor unit is stopped and the indoor unit in operation by degrees sensors, temperature difference between the refrigerant temperature of the indoor unit is stopped and the refrigerant temperature of the indoor unit during operation, the an air conditioner having a control means for adjusting the opening degree of the electric expansion valve to a predetermined temperature difference calculated based on the outside air temperature sensor output.