JP4100135B2 - Refrigeration cycle apparatus and control method for refrigeration cycle apparatus - Google Patents

Refrigeration cycle apparatus and control method for refrigeration cycle apparatus Download PDF

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JP4100135B2
JP4100135B2 JP2002323754A JP2002323754A JP4100135B2 JP 4100135 B2 JP4100135 B2 JP 4100135B2 JP 2002323754 A JP2002323754 A JP 2002323754A JP 2002323754 A JP2002323754 A JP 2002323754A JP 4100135 B2 JP4100135 B2 JP 4100135B2
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compressor
refrigerant
throttle means
opening degree
refrigeration cycle
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JP2004156858A (en
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哲二 七種
佳宏 高橋
正則 青木
寿彦 榎本
和樹 岡田
正信 馬場
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Mitsubishi Electric Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/02—Compressor control
    • F25B2600/021—Inverters therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2106—Temperatures of fresh outdoor air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B31/00—Compressor arrangements
    • F25B31/002—Lubrication
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

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  • Air Conditioning Control Device (AREA)

Description

【０００１】
【発明の属する技術分野】
この発明は、例えば空気調和装置等の冷凍サイクルを用いた冷凍サイクル装置及び冷凍サイクル装置の制御方法に関するものである。
【０００２】
【従来の技術】
従来の空気調和装置等の冷凍サイクル装置において、冷媒としてＨＦＣ系冷媒が封入され、圧縮機に充填される冷凍機油としてＨＦＣ系冷媒に対して弱相互溶解性の鉱物油やアルキルベンゼン系油を用いた場合、圧縮機より流出した冷凍機油の返油性能が悪いという問題点が生じる。このため、従来の例えば冷凍装置においては、冷却負荷が小さく圧縮機を低回転数で連続運転する必要がある場合に、圧縮機を所定時間高速運転して冷凍機油を圧縮機に返油する構成としている（例えば、特許文献１参照。）。
【０００３】
【特許文献１】
特開２００１−２０８４３５号公報（第４ページ、図３）
【０００４】
【発明が解決しようとする課題】
従来の弱相互溶解性の冷凍機油を用いた冷凍装置では、圧縮機を連続して低回転数で運転する場合にのみ、所定時間高回転数で運転している。ところが、冷凍サイクル装置として例えば空気調和装置などで暖房運転を行う際、圧縮機と凝縮器を接続する高圧ガス管や蒸発器と圧縮機を接続する低圧ガス管において、ガス冷媒が冷凍機油にほとんど溶解しない。このため、冷凍機油の動粘度は、冷媒回路内を純粋な冷凍機油の動粘度と同等の状態で流動するので返油されにくい。また、外気温度が低い状態で運転起動された場合に、特に問題が生じる。外気温度が低い状態での運転起動時には、蒸発温度の低下による冷媒中への冷凍機油の溶解量の減少や、冷凍機油の動粘度がさらに大きくなり、圧縮機より流出する冷凍機油は冷媒回路内に長時間滞留して圧縮機への返油性能が悪化する。これにより、圧縮機内の冷凍機油が不足して圧縮機摺動部の潤滑不良による焼付きや異常磨耗が生じるなど、運転に支障をきたすという問題があった。
【０００５】
また、冷凍サイクル装置の運転停止時に蒸発器に多くのニ相冷媒が溜まった状態で停止している冷凍サイクル装置を起動すると、蒸発器に溜まりこんでいた二相冷媒は圧縮機へ流入する。そして圧縮されて高温高圧の二相冷媒として吐出管より吐出されるのであるが、この高温高圧の二相冷媒のうち液冷媒の一部は、圧縮機より吐出されずに圧縮機シェルの底に溜まり込む。弱相互溶解性油は比重の大きい液冷媒の上部に押上げられ、吐出管より冷凍サイクルへ流出しやすくなり、圧縮機内の冷凍機油が不足するという問題があった。
【０００６】
この発明は、上記のような問題点を解消するためになされたもので、冷媒に対して弱相互溶解性の冷凍機油を用いた冷凍サイクルにおいて、特に蒸発器の周囲温度が低くなる運転時に、冷凍機油を確実に圧縮機に返油させ、信頼性の高い冷凍サイクル装置を得ることを目的とする。
また、この発明は、冷凍サイクル装置の起動時に、圧縮機への液バックを低減して、信頼性の高い冷凍サイクル装置を得ることを目的とする。
【００１０】
また、この発明に係わる冷凍サイクル装置は、前記蒸発器の周辺温度を検知する温度センサーと、前記圧縮機吐出側の冷媒状態を検知する冷媒状態検知手段と、を備え、前記制御手段は、前記温度センサーで検知した蒸発器周辺温度と前記圧縮機の運転周波数に対して、前記冷媒状態検知手段で検知した前記圧縮機吐出側の冷媒状態が目標状態に安定すると推定される前記絞り手段の開度を最低開度に設定し、前記絞り手段を前記最低開度より大きな開度で制御することを特徴とするものである。
【００１１】
また、この発明に係わる冷凍サイクル装置は、前記蒸発器の周辺温度を検知する温度センサーを備え、前記制御手段は、前記絞り手段の起動開度を前記温度センサーで検知した蒸発器周辺温度に対して予め設定された時間内で返油し得る開度に設定して絞り手段起動運転を開始することを特徴とするものである。
【００１６】
【課題を解決するための手段】
この発明に係わる冷凍サイクル装置は、圧縮機、凝縮器、絞り手段、蒸発器を接続して冷媒を循環させる冷媒回路を有し、前記冷媒に対して弱相互溶解性の冷凍機油を用いた冷凍サイクルと、前記圧縮機出口側の圧縮機吐出スーパーヒートを検知する圧縮機吐出スーパーヒート検知手段と、前記圧縮機吐出スーパーヒート検知手段で運転起動後に初めて圧縮機吐出スーパーヒートがついたことを検知した時に前記絞り手段の開度を増加させる制御手段と、を備えたものである。
【００１８】
また、この発明に係わる冷凍サイクル装置は、圧縮機、蒸発器、第１絞り手段、液溜め手段、第２絞り手段、凝縮器を順次接続して冷媒を循環させる冷媒回路を有し、前記冷媒に対して弱相互溶解性の冷凍機油を用いた冷凍サイクルにおいて、前記第２絞り手段の開度を第２絞り手段の起動開度に設定する第２絞り手段起動運転と、前記第２絞り手段起動運転の後に前記第２絞り手段を前記起動開度よりも小さい定常開度に設定すると共に、前記第１絞り手段の開度を所定開度大きくする収束移行運転と、前記収束移行運転の後に前記第２絞り手段の開度を増減して前記凝縮器の出口側の冷媒状態を制御する第２絞り手段収束制御運転と、を行なう制御手段を備えたものである。
【００１９】
また、この発明に係わる冷凍サイクル装置は、冷凍サイクル内に液溜め手段を備えると共に、冷凍機油量に対して３倍以上の冷媒量を封入したことを特徴とするものである。
【００２０】
また、この発明に係わる冷凍サイクル装置において、冷媒は、ＨＦＣ冷媒または自然冷媒を用いることを特徴とするものである。
【００２１】
また、この発明に係わる冷凍サイクル装置において、冷凍機油は、動粘度８〜３２ｃＳｔのアルキルベンゼン系油を用いることを特徴とするものである。
【００２２】
また、この発明に係る冷凍サイクル装置の制御方法は、圧縮機の周波数を徐々に上げ、前記周波数に伴って絞り手段の開度を起動開度に設定する起動ステップと、前記圧縮機が負荷に応じた所定の回転数に達した後に前記絞り手段の開度を前記起動開度よりも小さく絞って増減させ、圧縮機出口側の冷媒状態を目標状態に近づける絞り手段収束ステップと、蒸発器周辺温度または圧縮機シェル温度に対して、前記起動ステップの運転時間または前記絞り手段収束ステップの前記絞り手段の開度増減幅を制御する収束時間制御ステップと、を備えたものである。
【００２４】
また、この発明に係わる冷凍サイクル装置の制御方法は、冷媒貯溜手段の上流側絞り手段を起動開度に設定して運転する上流側絞り手段起動ステップと、前記上流側絞り手段起動ステップの後に前記上流側絞り手段の開度を増減させて凝縮器出口側の冷媒状態を目標状態に近づける上流側絞り手段収束ステップと、前記上流側絞り手段起動ステップから前記上流側絞り手段収束ステップに移るときの前記上流側絞り手段の開度の減少による冷媒流量の減少を緩和するように前記冷媒貯溜手段の下流側絞り手段の開度を増加させる収束移行ステップと、を備えたものである。
【００２５】
また、この発明に係わる冷凍サイクル装置の制御方法は、圧縮機吐出スーパーヒートを検知する圧縮機吐出スーパーヒート検知ステップと、前記圧縮機吐出スーパーヒート検知ステップで初めて前記圧縮機吐出スーパーヒートがついたことを検知したときに絞り手段の開度を増加させる開度増加ステップと、前記絞り手段の開度を増減させて圧縮機出口側の冷媒状態を目標状態に近づける絞り手段収束ステップと、を備えたものである。
【００２６】
【発明の実施の形態】
実施の形態１．
図1はこの発明の実施の形態1に係る冷凍サイクル装置として、例えば空気調和装置の冷凍サイクルを示す構成図である。また、図２はこの実施の形態に係る圧縮機運転周波数の制御フローチャートであり、図３はこの実施の形態に係る外気温度に対する冷媒流量と返油時間の関係を示す。
【００２７】
図１において、圧縮機１、暖房時には蒸発器、冷房時には凝縮器として動作する熱交換器３、第１絞り手段である例えば第１絞り装置４ａ、液溜め手段である例えばレシーバ７、第２絞り手段である例えば第２絞り装置４ｂ、暖房時には凝縮器、冷房時には蒸発器として動作する熱交換器５、暖房運転と冷房運転とで冷媒の循環方向を切換える流路切換手段例えば四方弁２を冷媒配管で接続して冷凍サイクルを構成している。
なお、図1の冷凍サイクル装置は、例えば冷凍サイクル装置として空気調和装置の暖房運転時の状態を示しており、この実施の形態では、例えば熱交換器３を室外に設置した室外熱交換器とし、熱交換器５を室内に設置した室内熱交換器として、熱交換器３を蒸発器とし、熱交換器５を凝縮器として動作させて室内の暖房運転を行なう場合について説明する。
【００２８】
室外熱交換器３を設置する場所と室内熱交換器５を設置する場所の間の距離によって、冷凍サイクルを構成する冷媒配管長が異なり、冷媒配管長に応じて充填冷媒量が異なる。例えば、図１に示す冷凍サイクルでは、配管イと配管ロの間及び配管ハと配管ニの間を延長配管で接続する。また、暖房運転と冷房運転や負荷に応じても冷凍サイクル内を循環する冷媒量の必要な量が異なる。液溜め手段であるレシーバ７は、余剰冷媒液溜め用の容器で、運転や負荷や延長配管の長さによって最適量の冷媒が冷凍サイクルを循環するように、余剰冷媒を滞留するための容器である。第1絞り装置４ａは、例えば室外熱交換器３とレシーバ７との間の冷媒配管に設けられた電子膨張弁で、開度を変化させることで、この配管を流れる冷媒流量を可変にできる。同様に、第２絞り装置４ｂは、例えば室内熱交換器５とレシーバ７との間の冷媒配管に設けられた電子膨張弁で、開度を変化させることで、この配管を流れる冷媒流量を可変にできる。
【００２９】
また、外気温度センサー５１によって蒸発器として動作する室外熱交換器３の周辺の温度、例えば外気温度が検知でき、室内温度センサー５２によって室内熱交換器５の周辺の温度、例えば室内温度が検知できる。制御手段である例えば制御装置１１は、図４のブロック図で示すように構成され、例えば温度センサー５１、５２からの計測温度の入力部１１ａと記憶部１１ｂと演算処理部１１ｃを有するマイクロコンピュータ、及び圧縮機駆動回路１１ｄであり、温度センサー５１、５２で検知した温度に基づいて圧縮機１の周波数を制御する。
【００３０】
この冷凍サイクルに用いた冷媒は、ＨＦＣ冷媒、例えばＲ３２とＲ１２５の混合冷媒であるＲ４１０Ａであり、冷凍機油は、アルキルベンゼン系油など、冷媒に対して弱相互溶解性でかつ油比重が液冷媒の比重よりも小さい冷凍機油を用いる。弱相互溶解性の冷凍機油は、不純物が多少混入しても劣化しにくく安定性が維持でき、既成配管を使えるなど、多くの利点がある。
【００３１】
次に、このように構成された空気調和装置において、暖房運転初期の動作を説明する。暖房運転起動後、圧縮機１は室外熱交換器３に溜まりこんでいた二相冷媒を吸入管より吸入、圧縮し、高温高圧の二相冷媒として吐出管より吐出する。圧縮後の高温高圧の二相冷媒のうち液冷媒の一部は、圧縮機１より吐出されずに圧縮機シェルの底に溜まり込む。圧縮機１に封入されている弱相互溶解性油は比重の大きい液冷媒の上部に押上げられ、吐出管より冷凍サイクルへ流出する。なお、圧縮機１より流出する弱相互溶解性油の量は、封入されている冷媒量によって異なる。熱交換器３、５を設置する場所が離れている場合には、延長配管が長くなり必要冷媒量は多くなるが、冷凍機油の封入量はほとんど変わらないので、冷媒量が冷凍機油の量の３倍以上になることもある。特にこのように冷凍機油の封入量に対して冷媒の封入量が３倍以上に多くなるシステムにおいては、流出する弱相互溶解性油の量は極めて多くなる。
【００３２】
圧縮機１から吐出された高温高圧の二相冷媒は、四方弁２を通って室内熱交換器５に入り室内空気と熱交換し、乾き度の低い二相冷媒または液冷媒まで凝縮し、室内熱交換器５から流出する。室内熱交換器５から流出した乾き度の低い二相冷媒または液冷媒は第２絞り装置４ｂを通って中間圧に減圧され、乾き度の小さい二相冷媒となってレシーバ７に流入する。レシーバ７に流入した乾き度の小さい二相冷媒は、レシーバ７内に挿入された圧縮機１の吸入側に接続された低圧低温の吸入配管９と熱交換する。そして、乾き度がさらに小さい二相冷媒または飽和液冷媒となってレシーバ７から流出する。レシーバ７から流出した乾き度の小さい二相冷媒または飽和液冷媒は第１絞り装置４ａを通って低圧の二相冷媒となり、室外熱交換器３へ流入する。
【００３３】
室外熱交換器３に流入した低圧二相冷媒は、外気と熱交換し乾き度の高い低圧二相冷媒となって室外熱交換器３から流出する。室外熱交換器３から流出した乾き度の高い低圧二相冷媒はレシーバ７に挿入された吸入配管９内を通り、レシーバ７内の中間圧冷媒と熱交換する。そして、乾き度のさらに高い低圧二相冷媒となり、四方弁２を介して圧縮機１の吸入側へ戻る。
【００３４】
一方、圧縮機１より吐出された弱相互溶解性油は、上記で説明した冷媒と同じ経路を通り、再び圧縮機1の吸入側へ戻ってくる。
【００３５】
以上のように、暖房運転初期は圧縮機１に封入されている弱相互溶解性油が液冷媒により押上げられて冷媒回路に流出するため、圧縮機１内の冷凍機油量が減少し、圧縮機摺動部の潤滑不良による焼付き、異常磨耗など信頼性が低減する可能性があった。特に弱相互溶解性油は冷媒の溶解度が小さいので、油動粘度が低下せず、さらに暖房運転の場合、蒸発温度が低温となり蒸発器３や低圧ガス配管で油動粘度が上昇する。このため、一旦圧縮機１から冷凍サイクルに流出した弱相互溶解性油が、再び圧縮機１の吸入部に返油されて圧縮機１内の冷凍機油量が回復するまでに、長い時間を要する。
【００３６】
図３は、延長配管（図１のイとロの間及びハとニの間の配管長）を５０ｍ、蒸発器３のパス数を４パスとした場合の実験により得られた冷媒流量（ｋｇ／ｈ）と返油時間（ｓｅｃ）の関係を示すグラフであり、横軸に冷媒流量（ｋｇ／ｈ）、縦軸に返油時間（ｓｅｃ）を示す。ここで、返油時間とは、圧縮機１から冷凍機油が吐出されてから圧縮機１に返油されるまでの時間である。３本の曲線は、上側からそれぞれ外気温度がー１０℃、０℃、７℃の場合の関係である。同じ冷媒流量であっても外気温度が低いほど、油の動粘度が高くなり長い返油時間を要することがわかる。
【００３７】
ここで、この実施の形態に係る圧縮機運転周波数の制御の一例を図２に示す制御フローチャートに基づいて説明する。制御装置１１は暖房運転起動指令を受ける（ＳＴ１）と圧縮機起動運転を行なう（ＳＴ２）。これは例えば圧縮機１を停止状態から徐々に周波数を上げていき、数分程度後には負荷に応じて周波数を増減する定常運転での周波数程度にする運転である。この後、リモコン等で設定された設定室内温度Ｔａｉｎｓｅｔを読み込む（ＳＴ３）。起動時の外気温度Ｔａｏを外気温度センサー５１により検知し（ＳＴ４）、予め設定された返油時間を満足するのに必要な最低冷媒流量Ｇｍｉｎを設定する（ＳＴ５）。これは、図３に示す外気温度Ｔａｏの時の冷媒流量と返油時間の関係から設定できる。次に最低冷媒流量Ｇｍｉｎが得られるように圧縮機最低運転周波数Ｈｚｍｉｎを設定する（ＳＴ６）。例えば、必要返油時間を１０分とすると、外気温度がー１０℃の時には６０（ｋｇ／ｈ）程度、０℃の時には４５（ｋｇ／ｈ）程度、７℃の時には３５（ｋｇ／ｈ）程度になるような圧縮機周波数が最低運転周波数Ｈｚｍｉｎとして設定される。
【００３８】
次に室内温度Ｔａｉｎを室内温度センサー５２により検知し（ＳＴ７）、設定室内温度Ｔａｉｎｓｅｔとの差（Ｔａｉｎｓｅｔ― Ｔａｉｎ）に応じて圧縮機運転周波数の変更量ΔＨｚを計算し（ＳＴ８）、圧縮機運転周波数Ｈz＝Ｈz＋ΔＨｚを算出する（ＳＴ９）。ここで算出した圧縮機運転周波数Ｈzが圧縮機最低運転周波数Ｈｚｍｉｎよりも小さいかどうか判断し（ＳＴ１０）、圧縮機運転周波数Ｈｚ＜圧縮機最低運転周波数Ｈｚｍｉｎと判断された場合には、圧縮機運転周波数Ｈｚを圧縮機最低運転周波数Ｈｚｍｉｎとする（ＳＴ１１）。ＳＴ７〜ＳＴ１１の制御は暖房運転の間を通じて行われる。
【００３９】
このように、図２に示す制御処理では、圧縮機運転周波数Ｈｚの下限値を設け、冷媒流量が予め設定された返油時間を満足する最低冷媒流量を下回らないように運転する。この最低冷媒流量とは圧縮機１から流出した冷凍機油が予め定めた所定の時間、例えば１０分程度で圧縮機１に返油されるような冷媒流量の最低値である。圧縮機１には予め冷凍機油の必要最低油量が通常は液面高さで定まっており、圧縮機１内の冷凍機油の量がこの液面よりも下がると運転に支障をきたす。返油時間は、少なくとも圧縮機１内に滞留している冷凍機油の量が必要最低油量以下にならないうちに、圧縮機１に返油されるように設定する。冷凍サイクルを循環する冷媒流量をこのように確保することで、圧縮機１より冷媒回路に流出した弱相互溶解性の冷凍機油は、所定時間内に再び圧縮機吸入部に返油され、圧縮機１内の冷凍機油量が長時間減少した状態になるのを防ぐことができる。従って、圧縮機摺動部の潤滑不良による焼付きや異常磨耗などが生じるのを防止でき、信頼性を向上できる。
なお、圧縮機１で予め定まっている冷凍機油の必要最低油量は、液面高さとして定まっており、圧縮機１内で冷凍機油の下部に液冷媒ある状態で必要最低油量に達している場合でも、液冷媒の量によるが、圧縮機１をある程度支障なく運転できることもある。
【００４０】
また、従来装置では、圧縮機を低回転数で連続運転する場合に高回転数運転を行っているが、この実施の形態では、起動時の外気温度に基づいて最低運転周波数Ｈｚｍｉｎを設定し、運転中を通じて最低運転周波数Ｈｚｍｉｎ以上となるように制御する。このため、運転初期に蒸発器３に溜まった液バックが生じて冷凍機油の流出量が多くなる時、及び運転中に負荷が小さくなって圧縮機周波数が小さくなる時に、返油が可能な冷媒流速を確保できる。即ち、運転中を通して冷凍サイクル内に冷凍機油が滞留するのを防止し、確実に圧縮機１に返油できる。
【００４１】
また、図２に示すような制御では、室内温度Ｔａｉｎを設定室内温度Ｔａｉｎｓｅｔに近づけるように計算した圧縮機運転周波数Ｈｚが最低冷媒流量Ｇｍｉｎが得られる最低周波数Ｈｚｍｉｎ以上である場合には、周波数Ｈｚを変更しない。このように、無駄に周波数Ｈｚを大きくしないので、能力が過大になったり必要以上に消費電力が増えることなく、効率のよい運転を行うことができる。
【００４２】
また、複数の外気温度に対して予め試験などで得られたデータ（図３）に基づき、所定の返油時間が得られるように冷媒流量を設定している。これにより、圧縮機１から吐出した冷凍機油が所定時間経って確実に圧縮機１に戻ってくるので、さらに信頼性の高い冷凍サイクル装置が得られる。
【００４３】
ＳＴ５、ＳＴ６で、最低冷媒流量Ｇｍｉｎ、最低運転周波数Ｈｚｍｉｎを計算する時、例えば予め制御装置１１の記憶部にテーブルで実験データまたは経験データを与え、これを参照する。この様に処理すると、暖房運転起動指令時に処理が簡単であり、短時間に計算できる。なお、テーブルでデータを記憶する代わりに演算式によって計算してもよい。
また、ＳＴ５、ＳＴ６で外気温度Ｔａｏに対してまず最低冷媒流量Ｇｍｉｎを設定した後に最低運転周波数Ｈｚｍｉｎを設定したが、Ｈｚｍｉｎ＝ｆ（Ｔａｏ）となるようにテーブルを作成してもよい。
【００４４】
また、例えば外気温度Ｔａｏに対して、その温度での返油を満足する圧縮機最低運転周波数Ｈｚｍｉｎをデータとしてテーブルで与える際、そのデータ数はいくつでもよいが、少なくとも３以上の外気温度Ｔａｏに対して最低運転周波数Ｈｚｍｉｎを設定するのが好ましい。この実施の形態では、例えば外気温度が０℃よりも小さい場合に６０（ｋｇ／ｈ）、０℃〜７℃の場合に４５（ｋｇ／ｈ）、７℃以上の場合に３５（ｋｇ／ｈ）が得られるように、３つの温度範囲で最低運転周波数Ｈｚｍｉｎを設定している。外気温度に対して適切な最低運転周波数となるように設定するのが好ましいが、少なくとも３以上の外気温度に対して最低運転周波数を設定した場合、能力が過大になったり必要以上に消費電力が増えるのをある程度防止できる。例えば空気調和装置などの暖房運転を行なう場合、外気温度がー１５℃〜４０℃という広範囲に対して、返油を満足するように圧縮機最低周波数Ｈｚｍｉｎを決定する必要がある。これを２段階の最低運転周波数で制御しようとすると、ある温度範囲ではその温度範囲の低い方の温度の条件での圧縮機最低運転周波数Ｈｚｍｉｎで運転することになる。外気温度がその温度範囲の高い方に近い場合の運転においては、能力がある程度過大になることがあり、快適性が悪化したり、消費電力が増加する。このため、温度範囲はなるべく小さく設定するのが望ましいが、少なくとも３段階以上の温度範囲で設定するのが好ましい。このとき、図３で必要返油時間における冷媒流量の差を考慮して温度範囲を設定するとよい。また、３段階より少ないデータしか与えない場合、そのデータ間を推測して返油が満足するように圧縮機最低周波数を計算し、制御は記憶部１１ｂのデータ数よりも多い多段階の温度範囲で行なうようにしてもよい。
【００４５】
また、この実施の形態における冷凍サイクル装置は、レシーバ７を有しているので、設置場所に応じて必要冷媒量が異なる場合でも、予め見込まれる最大の必要冷媒量を充填しておけばよい。設置場所に応じて生じる余剰冷媒は、レシーバ７に貯溜された状態で運転される。このため、設置現場での手順が簡単にできる。
【００４６】
図５はこの発明の実施の形態1に係る冷凍サイクル装置として、例えば空気調和装置の冷凍サイクルの他の構成例を示す構成図である。また、図６にこの実施の形態における第１絞り装置の制御フローチャートを示す。
なお、図５において、図１と同一符号は同一、または相当部分を示している。また、暖房運転起動指令の初期の冷媒および弱相互溶解性油の動作については、図１を用いて説明した前述の内容と同じであるため、省略する。
【００４７】
図５において、温度センサー５３は圧縮機１の吐出部に設けられ、吐出部付近の温度、即ち吐出温度を検知する。制御手段である制御装置１２の構成は図４に示す制御装置１１と同様であるが、制御装置１２は第１絞り装置４ａの開度を制御するための駆動回路を有している。制御装置１２は、例えば外気温度センサー５１、吐出温度センサー５３、凝縮温度センサー５４からの温度入力部と記憶部と演算処理部を有するマイクロコンピュータ、及び第１絞り装置４ａの駆動回路であり、温度センサー５１、５３、５４で検知した温度に基づいて第１絞り装置４ａの開度を制御する。
【００４８】
以下、この実施の形態に係る第１絞り装置４ａの開度の制御の一例を、図６に示す制御フローチャートに基づいて説明する。暖房運転起動指令によって圧縮機１は起動運転を行なう際、第１絞り手段である第１絞り手段４ａは予め定められている起動開度に設定される。そして圧縮機１が定常運転を行なうあたりで、圧縮機１の吐出側の冷媒状態が目標状態になるように第１絞り装置４ａの開度が制御される。例えば圧縮機１の吐出部付近の温度である吐出温度を、予め設定された目標吐出温度に向かって収束するように、第１絞り装置４ａの開度を増減して制御する。図６に示す制御フローチャートは、この第１絞り装置４ａの収束制御運転の動作に関するものである。
【００４９】
制御装置１２は第１絞り装置４ａの収束制御運転が開始される（ＳＴ１２）と、外気温度Ｔａｏを外気温度センサー５１により検知する（ＳＴ１３）。そして外気温度Ｔａｏに対応して予め設定された第１絞り装置最低開度Ｐ１ｍｉｎを設定する（ＳＴ１３）。予め例えば制御装置１２の記憶部に、複数の外気温度に対応して、それぞれの外気温度の時に目標吐出温度に収束する第1絞り装置４ａの安定開度を第１絞り装置最低開度Ｐ１ｍｉｎとしてテーブルで記憶しておく。そしてＳＴ１３では、外気温度センサー５１により検知された外気温度Ｔａｏに対して、第１絞り装置最低開度Ｐ１ｍｉｎを決定する。
【００５０】
次にＳＴ１４〜ＳＴ２０で、運転中の吐出温度Ｔｄが目標吐出温度Ｔｄｐに近づくように収束制御を行う。即ち、吐出温度Ｔｄを吐出温度センサー５３により検知し（ＳＴ１４）、吐出温度Ｔｄと目標吐出温度Ｔｄｐとの温度差ΔＴｄを計算する（ＳＴ１５）。この温度差ΔＴｄをゼロにするように第１絞り装置４ａの開度変更量ΔＰ１を計算し（ＳＴ１６）、現在の第1絞り装置４ａの開度を開度変更量ΔＰ１だけ変更して次の第１絞り装置開度Ｐ１を決定する（ＳＴ１７）。ここで、決定した第１絞り装置開度Ｐ１が第１絞り装置最低開度Ｐ１ｍｉｎよりも小さいかどうか判断し（ＳＴ１８）、小さくなった場合、第１絞り装置開度Ｐ１を第１絞り装置最低開度Ｐ１ｍｉｎに決定しなおす（ＳＴ１９）。そして、第１絞り装置４ａの開度を、ＳＴ１７、ＳＴ１９で決定した第１絞り装置開度Ｐ１に変更する（ＳＴ２０）。
【００５１】
このように、この実施の形態によれば、外気温度Ｔａｏに応じて予め目標吐出温度Ｔｄｐに収束する第１絞り装置開度Ｐ１が、第1絞り装置最低開度Ｐ１ｍｉｎよりも小さくなることを防止している。計測した吐出温度Ｔｄに基づいて第１絞り装置４ａの開度Ｐ１の変更を決定しているのであるが、例えば過渡的な温度センシングの遅れなどが生じると、第1絞り装置４ａを必要以上に絞り込むように第１絞り装置４ａの開度Ｐ１が変更される可能性がある。最低開度Ｐ１ｍｉｎを設けることで、第1絞り装置４ａを必要以上に絞り込むのを防止でき、過渡的な吸入圧力低下、冷媒循環量の減少、蒸発温度の低下等が起こるのを防止することができる。従って、十分な油移動速度を確保し、圧縮機１より冷媒回路に流出した弱相互溶解性油が再び圧縮機吸入部に返油されず長時間圧縮機内の油量が減少することを防止でき、圧縮機摺動部の潤滑不良による焼付き、異常磨耗を防止して信頼性を向上できる。
【００５２】
なお、この実施の形態における冷凍サイクル装置は、図２と図６に示した制御処理のどちらか一方を備えてもよいし、両方の制御処理を備えてもよい。
また、外気温度センサー５１で外気温度を検知し、外気温度に基づいて制御を行っている。この代わりに、蒸発器３が格納されている容器内の温度や、蒸発器３の途中の冷媒配管の温度を検知する温度センサーを設け、蒸発温度を検知して蒸発温度に基づいて制御を行ってもよい。蒸発温度が低い場合に冷媒流量が多くなるように制御するのは、外気温度を用いる場合と同様である。
また、図６に示す制御では吐出温度が目標温度になるように第１絞り装置４ａの開度を制御しているが、吐出温度の代わりに、圧縮機吐出スーパーヒートによって冷媒状態を目標状態に近づくように制御してもよい。この圧縮機吐出スーパーヒートは吐出温度センサー５３で検知した圧縮機１の吐出温度と、凝縮温度センサー５４で検知した凝縮器５の凝縮温度から演算できる。
【００５３】
実施の形態２．
図７はこの発明の実施の形態２に係る冷凍サイクル装置として、例えば空気調和装置の冷凍サイクルを示す構成図である。なお、図７の冷凍サイクルは暖房運転時の状態を示しており、図８はこの実施の形態に係る第１絞り装置４ａの制御フローチャートである。なお、図７中、図１に示す各部と同一符号は、同一または相当部分であり、ここではその説明を省略する。
【００５４】
図７において、制御手段である制御装置１３の構成は図４に示す制御装置１１と同様であるが、制御装置１３は第１絞り装置４ａの開度を制御するための駆動回路を有している。制御装置１３は、例えば外気温度センサー５１、凝縮温度センサー５４、圧縮機シェル温度センサー５５で検知した温度を入力する温度入力部と記憶部と演算処理部を有するマイクロコンピュータ、及び第１絞り装置４ａの駆動回路であり、外気温度センサー５１で検知した外気温度に基づいて第１絞り装置４ａの開度を制御する。また、凝縮器５の配管に設けた凝縮温度センサー５４で凝縮温度を検知でき、圧縮機１の吐出部設けた吐出温度センサー５３で圧縮機１の吐出温度を検知できる。検知した凝縮温度及び吐出温度は制御装置１３の入力部に入力される。
【００５５】
以下、この実施の形態に係る第１絞り手段である第１絞り装置４ａの開度の制御の一例を、図８の制御フローチャートに基づいて説明する。冷凍サイクルを動作させる際、第１絞り手段である第１絞り装置４ａは、第１絞り装置起動運転と第１絞り装置収束制御運転の２種類の制御運転を行なう。即ち、第１絞り装置起動運転は、暖房起動後予め設定された時間、例えば数分間の間、予め定められている起動開度に設定する運転である。次の収束制御運転における定常的な開度を定常開度と称し、起動運転における起動開度は定常開度よりも開度を大きく設定される。また、第１絞り装置収束制御運転は、例えば図６に示したように、第１絞り装置起動運転終了後に吐出温度センサー５３で検知した圧縮機吐出温度が予め設定された目標値に近づくように、開度を定常開度から増減して調整する制御運転である。図８に示す制御フローチャートは、この第１絞り装置起動運転において、第１絞り装置４ａに設定する起動開度に関するものである。
【００５６】
第１絞り装置起動運転において、制御装置１３は暖房運転起動指令を受けた（ＳＴ２１）後、外気温度センサー５１により外気温度Ｔａｏを検知する（ＳＴ２２）。そして、外気温度Ｔａｏと予め設定された第１の基準値の値を比較し（ＳＴ２３）、第１の基準値を下回った場合は、第１絞り装置４ａの起動開度Ｐを第１設定開度Ｐ１とする（ＳＴ２４）。一方、外気温度Ｔａｏが予め設定された第１の基準値以上の場合は、第１絞り装置４ａの起動開度Ｐを第２設定開度Ｐ２とする（ＳＴ２５）。ＳＴ２４、ＳＴ２５で第１絞り装置４ａの開度が設定された後、第１絞り装置４ａの起動運転を開始する（ＳＴ２６）。第１絞り装置起動運転は、ＳＴ２４、ＳＴ２５で設定された第１絞り装置４ａの起動開度Ｐで、所定時間、例えば数分程度の間、第１絞り装置４ａの開度Ｐを一定とするか、または圧縮機周波数を上げるにつれて、第１絞り装置４ａの開度Ｐを徐々に大きくする。どちらにしても、第１絞り装置収束制御運転における第１絞り装置４ａの定常開度よりも大きく設定されている。ＳＴ２６で第１絞り手段起動運転を開始した後、数分経ってから、例えば図６に示したように吐出温度に応じて開度を増減させる第１絞り装置収束制御運転となる。
【００５７】
ＳＴ２４で設定した第1絞り装置４ａの第１設定開度Ｐ１は、ＳＴ２５で設定した第１絞り装置４ａの第２設定開度Ｐ２よりも大きく設定する。図９は外気温度に対して、ある予め設定した所定の返油時間、例えば１０分程度で返油されるために必要な冷媒流量を示すグラフであり、横軸に外気温度（℃）、縦軸に冷媒流量（ｋｇ／ｈ）を示している。外気温度が低くなるほど弱相互溶解性油の油動粘度が増加し、冷媒流量を大きくする必要がある。この実施の形態によれば、外気温度Ｔａｏが予め設定された第１の基準値を下回った場合、第１絞り装置４ａの起動開度を大きく設定するため、外気温度が低い場合に大きな冷媒流量が得られる。例えば、ＳＴ２３で比較する第１の基準値を０℃とし、外気温度が０℃よりも小さくなったときには、６０ｋｇ／ｈ程度の冷媒流量が得られるように開度を設定し、０℃以上の時には、４３ｋｇ／ｈ程度の冷媒流量が得られるように開度を設定すればよい。
【００５８】
第１絞り装置４ａの開度Ｐをこのように外気温度Ｔａｏに対して所定の時間で返油するように設定することにより、起動時に冷凍サイクルを循環する最低冷媒流量を確保できる。この最低冷媒流量とは圧縮機１から流出した冷凍機油が予め定めた所定の時間、例えば１０分程度で圧縮機１に返油されるような冷媒流量の最低値である。冷凍サイクルを循環する冷媒流量をこのように確保することで、圧縮機１より冷媒回路に流出した弱相互溶解性油が再び圧縮機吸入部に返油されず長時間圧縮機内の油量が減少することを防止でき、圧縮機１内の冷凍機油量を必要最低油量以上に維持して、圧縮機摺動部の潤滑不良による焼付き、異常磨耗などを防止でき、信頼性を向上できる。
【００５９】
また、第１の基準値を０℃とした場合の処理について記載したが、これに限るものではない。冷媒流量の幅が均等になるように第１の基準値を設定するのが好ましい。例えば、図９のような関係がある場合には、冷媒流量が均等になる温度であるー４℃程度を設定すると、外気温度によっては能力がある程度過大になるのを低減でき、快適性の悪化及び消費電力の増加を低減できるので好ましい。
【００６０】
図８に示す制御処理では、起動開度をＰ１とＰ２の２つの開度のどちらかに設定する構成としたが、これに限るものではなく、外気温度に対して２つ以上の開度のいずれかに設定するようにすればよい。外気温度に対する起動開度のデータを多くすることで、能力が過大になるのをさらに低減でき、快適性の悪化及び消費電力の増加を低減できるので好ましい。
【００６１】
また、この発明の実施の形態２に係る他の構成例について説明する。図１０はこの実施の形態に係る制御フローチャートである。冷凍サイクル装置の構成は図７と同様である。
以下、この実施の形態に係る制御の一例を、図１０の制御フローチャートに基づいて説明する。ここで説明する制御処理は、主に起動後予め設定された時間まで行う起動運転に関するものである。特に空気調和装置で暖房運転指令がなされた場合、定常開度よりも開度を大きく設定する第１絞り装置起動運転を開始してから、第１絞り装置収束制御運転に移行するまでの移行時間ｔｓ、即ち絞り開始時期を制御している。
【００６２】
第１絞り装置起動運転において、制御装置１３は暖房運転起動指令を受けた（ＳＴ３１）後、外気温度センサー５１により外気温度Ｔａｏを検知する（ＳＴ３２）。そして、外気温度Ｔａｏと予め設定された第２の基準値の値を比較し（ＳＴ３３）、第２の基準値を下回った場合は、第１絞り装置収束制御運転への移行時間ｔｓを第１設定時間αとする（ＳＴ３４）。一方、外気温度Ｔａｏが予め設定された第２の基準値を上回った場合は、第１絞り装置収束制御運転への移行時間ｔｓを第２設定時間βとする（ＳＴ３５）。ＳＴ３４、ＳＴ３５で第１絞り装置収束制御運転への移行時間ｔｓ設定後、第１絞り装置４ａの起動運転（起動ステップ）を行なう（ＳＴ３６）。
【００６３】
ＳＴ３６での第１絞り装置４ａの起動開度は、例えば収束制御運転における第１絞り装置４ａの定常開度よりも大きな開度に設定する。ＳＴ３７で数分程度に設定された移行時間ｔｓの間、第１絞り装置起動運転（ＳＴ３６）を行い、移行時間ｔｓ経過した後、第１絞り装置収束制御運転（収束ステップ）を開始する（ＳＴ３８）。
【００６４】
ＳＴ３４で設定した第１設定時間αは、ＳＴ３５で設定した第２設定時間βよりも長く設定する。図１１は外気温度に対して、ある冷媒流量とした時の返油時間を示すグラフであり、横軸に外気温度（℃）、縦軸に冷媒流量（ｋｇ／ｈ）を示している。外気温度が低くなるほど弱相互溶解性油の油動粘度が増加し、返油時間は長くなる。この実施の形態によれば、外気温度Ｔａｏが予め設定された第２の基準値を下回った場合、第１絞り装置４ａの起動運転から収束制御運転への移行時間ｔｓを長く設定して収束制御運転を遅延させる。このため、暖房起動時に圧縮機1より冷媒回路に流出した弱相互溶解性油が圧縮機1まで十分返油された状態で、第１絞り装置４ａの収束制御運転に移行することが可能となる。例えば、ＳＴ３３で比較する第２の基準値を０℃とし、外気温度が０℃よりも小さくなったときには、６５０ｓｅｃ程度の移行時間ｔｓを設定し、０℃以上の時には、４５０ｓｅｃ程度の移行時間ｔｓを設定すればよい。
【００６５】
このように絞り装置４ａの開度を大きくする起動運転を外気温度Ｔａｏに対応した時間だけ行なうように起動運転の運転時間を制御することで、外気温度が低いときに外気温度が高いときよりも収束制御運転を遅延させている（収束時間制御ステップ）。このため、外気温度が低くて冷凍機油の動粘度が大きい時でも、絞り装置収束制御運転開始時には冷凍機油の大部分が返油され、圧縮機１の運転に支障をきたさない油量、即ち圧縮機１の必要最低油量以上の冷凍機油が圧縮機１内に滞留する。この状態で絞り装置４ａの収束制御を開始すると、しばらくすると圧縮機吐出スーパーヒートがつき、冷媒は圧縮機１からガス冷媒となって吐出され、圧縮機１内の液冷媒量はほとんどない。また、移行時間ｔｓを十分長く取ると、第１絞り装置４ａの収束制御運転への移行時点では、圧縮機シェル温度が上昇しており、圧縮機シェル温度が上昇した状態では、シェル内で液冷媒のほとんどが蒸発して吐出されるので圧縮機１内の液冷媒量はほとんどない。従って、運転起動時のように圧縮機１内の冷凍機油が液冷媒の上部に押し上げられて冷凍サイクルへ流出することはなく、十分な圧縮機油量を確保することができる。このため、圧縮機摺動部の潤滑不良による焼付き、異常磨耗などを防止でき、信頼性を向上できる。
【００６６】
ここで、圧縮機吐出スーパーヒートがつく状態とは、圧縮機１より吐出される冷媒が過熱ガスとなる状態であり、吐出温度センサー５３により検知される吐出温度と、凝縮器５に設置された凝縮温度センサー５４により検知される凝縮温度との差で演算される圧縮機吐出スーパーヒートが正の値となった状態である。前述のように圧縮機吐出スーパーヒートがつくと、冷凍機油は圧縮機１から冷凍サイクルにほとんど流出することはなくなる。また、圧縮機１内に液冷媒が滞留することがないので、圧縮機１内に圧縮機１の必要最低量の冷凍機油を滞留させてから圧縮機吐出スーパーヒートがつくように制御する。
【００６７】
また、第２の基準値を０℃とした場合の処理について記載したが、これに限るものではない。返油時間の幅が均等になるように第２の基準値を設定するのが好ましい。例えば、図１１のような関係がある場合には、返油時間が均等になる温度であるー５℃程度を設定すると、外気温度によって能力がある程度過大になるのを低減でき、快適性の悪化及び消費電力の増加を低減できるので好ましい。
【００６８】
また、図１０の処理工程では、移行時間をαとβの２つの時間のどちらかに設定する構成としたが、これに限るものではなく、外気温度に応じて２つ以上の移行時間のいずれかに設定するようにすればよい。
また、図１０のＳＴ３６における第１絞り装置４ａの開度は所定開度に設定してもよいし、図８で示したように、外気温度に応じて異なる開度になるように設定してもよい。
【００６９】
また、この発明の実施の形態２に係るさらに他の構成例について説明する。図１２はこの実施の形態に係る第１絞り装置４ａの制御フローチャートである。冷凍サイクル装置の構成は図７と同様である。
ここで説明する制御処理は、主に第１絞り装置起動運転終了後、吐出温度などを予め設定された目標値に収束するように、開度を定常開度から増減して調整する第１絞り装置収束制御運転に関するものである。特に、空気調和装置で暖房運転を行う際の第１絞り装置収束制御運転（収束ステップ）において、第１絞り装置開度変更量ΔＰを制御している。
【００７０】
第１絞り手段収束制御運転において、制御装置１３は第１絞り収束制御運転を開始する（ＳＴ４１）際、外気温度センサー５１により外気温度Ｔａｏを検知する（ＳＴ４２）。そして、外気温度Ｔａｏが予め設定された第３の基準値の値を比較し（ＳＴ４３）、第３の基準値を下回った場合は、第１絞り装置４ａの最大開度変更量ΔＰｍａｘを第１最大変更量Ｐ３とする（ＳＴ４４）。一方、外気温度Ｔａｏが予め設定された第３の基準値以上の場合は、第１絞り装置４ａの最大開度変更量ΔＰｍａｘを第２最大変更量Ｐ４とする（ＳＴ４５）。ＳＴ４４、ＳＴ４５で第１絞り装置４ａの最大開度変更量ΔＰｍａｘが外気温度に対応した最大開度変更量に設定される。
【００７１】
この後、吐出温度センサー５３により吐出温度Ｔｄを検知し（ＳＴ４６）、吐出温度Ｔｄと目標吐出温度Ｔｄｐの差ΔＴｄを計算する（ＳＴ４７）。この吐出温度差ΔＴｄに対して、目標吐出温度Ｔｄｐに近づくように第１絞り装置開度変更量ΔＰを計算する（ＳＴ４８）。ここで計算した第１絞り装置開度変更量ΔＰと、先に設定した第１絞り装置の最大開度変更量ΔＰｍａｘとを比較し（ＳＴ４９）、開度変更量ΔＰが最大開度変更量ΔＰｍａｘよりも大きい場合は、第１絞り装置開度変更量ΔＰを最大開度変更量ΔＰｍａｘとする（ＳＴ５０）。ＳＴ５１では、設定された開度ΔＰに従って第１絞り装置４ａの開度を変更する。この後、ＳＴ４６〜ＳＴ５１を繰り返すことで、第１絞り手段４ａは目標吐出温度が得られる開度に収束する。
【００７２】
図１２に示す制御処理により、外気温度Ｔａｏが予め設定された温度である第３の基準値を下回った場合、最大開度変更量ΔＰを小さく設定する。即ち、ＳＴ４４、ＳＴ４５で第１絞り装置４ａの最大開度変更量ΔＰｍａｘを設定する際、第１絞り装置４ａの第１最大変更量Ｐ３は第２最大変更量Ｐ４よりも小さく設定する。即ち第１絞り装置４ａの開度増減幅を制御することで収束時間を制御している（収束時間制御ステップ）。このため、外気温度が低い時には収束制御運転を開始してから吐出温度となるまでの時間を長く取ることになる。従って、圧縮機吐出スーパーヒートがつく時点または圧縮機シェル温度が上昇する時点では、起動時に圧縮機１より冷媒回路に流出した弱相互溶解性油が圧縮機１まで十分返油された状態となる。図１０に示した移行時間を長く設定した場合と同様、圧縮機吐出スーパーヒートがついてまたは圧縮機シェル温度が上昇し、圧縮機１内の液冷媒がほとんど蒸発しても、十分な圧縮機油量を確保することができる。このため、圧縮機摺動部の潤滑不良による焼付き、異常磨耗などを防止でき、信頼性を向上できる。
【００７３】
例えば、ＳＴ４３で比較する第３の基準値を０℃とし、Ｐ４を４５０ｓｅｃ程度で吐出温度になるような最大開度変更量に設定しておき、外気温度が０℃よりも小さくなったときには、Ｐ３をＰ４の０．７倍程度に設定すると、Ｐ３の最大開度変更量で運転した時には６５０ｓｅｃ程度で吐出温度になる。
また、第３の基準値を０℃とした場合の処理について記載したが、これに限るものではない。返油時間の幅が均等になるように第３の基準値を設定するのが好ましい。例えば、図１１のような関係がある場合には、返油時間が均等になる温度であるー５℃程度を設定すると、外気温度によって能力がある程度過大になるのを低減でき、快適性の悪化及び消費電力の増加を低減できるので好ましい。
【００７４】
図１２の処理工程では、第１絞り装置４ａの最大開度変更量ΔＰをＰ３とＰ４のどちらかに設定する構成としたが、これに限るものではなく、外気温度に応じて２つ以上の最大開度変更量ΔＰのいずれかに設定するようにすればよい。
【００７５】
また、この発明の実施の形態２に係るさらに他の構成例について説明する。図１３はこの実施の形態に係る制御フローチャートである。冷凍サイクル装置の構成は図７と同様である。
以下、この実施の形態に係る制御の一例を、図１３の制御フローチャートに基づいて説明する。ここで説明する制御処理は、図１０に示した処理と同様、主に起動後予め設定された時間まで行う起動運転に関するものである。特に空気調和装置で暖房運転指令がなされた場合、暖房運転起動後に、起動開度に設定して第１絞り装置起動運転を行ってから、第１絞り装置収束制御運転に移行するまでの移行時間ｔｓ、即ち絞り開始時期を制御している。
【００７６】
第１絞り装置起動制御において、制御装置１３は暖房運転起動指令を受けた（ＳＴ６１）後、圧縮機シェル温度センサー５５により圧縮機シェル温度Ｔｓｈｅｌｌを検知する（ＳＴ６２）。そして、圧縮機シェル温度Ｔｓｈｅｌｌと予め設定された第４の基準値の値を比較し（ＳＴ６３）、第４の基準値を下回った場合は、第１絞り装置収束制御運転への移行時間ｔｓを第３設定時間γとする（ＳＴ６４）。一方、圧縮機シェル温度Ｔｓｈｅｌｌが予め設定された第４の基準値以上の場合は、第１絞り装置収束制御運転への移行時間ｔｓを第４設定時間φとする（ＳＴ６５）。ＳＴ６４、ＳＴ６５で第１絞り装置収束制御運転への移行時間ｔｓが圧縮機シェル温度に対応して設定された後、第１絞り装置４ａの起動制御（起動ステップ）を行なう（ＳＴ６６）。
【００７７】
ＳＴ６６での第１絞り装置４ａの起動開度は、例えば収束制御運転における第１絞り装置４ａの定常開度よりも大きな所定の値を設定する。ＳＴ６７で設定された移行時間ｔｓの間、第１絞り装置起動運転（ＳＴ６６）を行い、移行時間ｔｓ経過した後、第１絞り装置収束制御運転（収束ステップ）を開始する（ＳＴ６８）。
【００７８】
ここで、ＳＴ６４で設定した第３設定時間γは、ＳＴ６５で設定した第４設定時間φよりも長く設定する。即ち圧縮機シェル温度Ｔｓｈｅｌｌが予め設定された第４の基準値を下回った場合、第１絞り装置４ａの起動運転から収束制御運転への移行時間ｔｓを長く設定する。逆に圧縮機シェル温度Ｔｓｈｅｌｌが予め設定された第４の基準値以上の場合、第１絞り装置４ａの収束制御運転への移行時間を短くする。このため、例えば、圧縮機シェル温度Ｔｓｈｅｌｌが低い初期起動の場合は第１絞り装置収束制御運転への移行時間を長くし、暖房起動時に圧縮機1より冷媒回路に流出した弱溶解性油が圧縮機まで十分返油された状態で、圧縮機シェル温度を上昇させることになる。例えば、ＳＴ６３で比較する第４の基準値を３０℃程度とし、圧縮機シェル温度が３０℃よりも小さいときには、６５０ｓｅｃ程度の移行時間ｔｓを設定し、３０℃以上の時には、３００ｓｅｃ程度の移行時間ｔｓを設定すればよい。
【００７９】
このように絞り装置４ａの開度を大きくする起動運転を圧縮機シェル温度Ｔｓｈｅｌｌに応じた時間行なって収束時間を制御する（収束時間制御ステップ）ことで、第１絞り装置４ａの収束制御運転を開始した時点では、圧縮機1より冷媒回路に流出した弱溶解性油が圧縮機１まで十分返油された状態で圧縮機吐出スーパーヒートがつき、圧縮機シェル温度が上昇する。この状態では、圧縮機１内で液冷媒のほとんどが蒸発して吐出されるので圧縮機１内の液冷媒量はほとんどなく、運転起動時のように圧縮機１内の冷凍機油が液冷媒の上部に押し上げられて冷凍サイクルへ流出するのを低減され、十分な圧縮機油量を確保することができる。従って、圧縮機摺動部の潤滑不良による焼付き、異常磨耗などを防止でき、信頼性を向上できる。
【００８０】
このように、図１３に示す制御処理では、圧縮機シェル温度が低い場合に、圧縮機１内に十分量の冷凍機油を確保した後に、圧縮機摺動部の潤滑不良による焼付き、異常磨耗など信頼性上の問題を防止することができる。一方、サーモオンオフ運転の場合のように、圧縮機シェル温度が高く、起動時に液冷媒が吸入されても圧縮機シェル内に液冷媒が溜まり込むことなく、大量の油吐出が生じない場合には、第１絞り装置４ａの収束制御への移行時間を短くすることにより、早めに吐出温度を目標温度に収束させることが可能となり、立上り性能を向上させることができる。
【００８１】
また、第４の基準値を３０℃とした場合の処理について記載したが、これに限るものではない。
また、図１３の処理工程では、移行時間をγとφの２つの時間のどちらかに設定する構成としたが、これに限るものではなく、圧縮機シェル温度に応じて２つ以上の移行時間のいずれかに設定するようにすればよい。また、図１３におけるＳＴ６６における第１絞り装置４ａの起動開度は所定開度に設定してもよいし、図８で示したように、蒸発器３の周辺温度に応じて異なる開度に設定してもよい。
【００８２】
ここで、図８のＳＴ２２、ＳＴ２３、図１０のＳＴ３２、ＳＴ３３、図１２のＳＴ４２、ＳＴ４３において、外気温度を検知して外気温度に対して起動開度、移行時間、開度変更量を設定したが、外気温度に限るものではない。蒸発器周辺温度センサーによって蒸発器周辺の空気の温度を検知して、この温度に対して各値を設定すればよい。例えば空気調和装置の冷房運転や冷凍機の場合には、冷房空間や冷却容器内の空気の温度となる。またこれらの温度の代わりに蒸発温度を用いてもよい。蒸発温度は、蒸発器の冷媒配管の温度を温度センサーで検知できる。蒸発温度が低い場合に冷媒流量が多くなるように制御したり、移行時間を長くしたり最大開度変更量を小さくして収束制御運転を遅延させるのは、外気温度を用いる場合と同様である。
【００８３】
実施の形態３．
図１４はこの発明の実施の形態３に係る冷凍サイクル装置として、例えば空気調和装置の冷凍サイクルを示す構成図である。なお、図１４の冷凍サイクルは暖房運転時の状態を示しており、図１５にこの実施の形態に係る第１絞り装置４ａおよび第２絞り装置４ｂの制御フローチャートを示す。なお、図１４中、図１に示す各部と同一符号は、同一または相当部分であり、ここではその説明を省略する。図１４において、制御手段である制御装置１４は第１、第２絞り装置４ａ、４ｂの開度を制御するための駆動回路を有する。
【００８４】
この実施の形態において、凝縮器５を室内、蒸発器３を室外に設置し、室内を暖房する暖房運転について説明する。上流側絞り手段である第２絞り装置４ｂは凝縮器５と冷媒貯溜手段であるレシーバ７の間の冷媒配管に配置され、下流側絞り手段である第１絞り装置４ａはレシーバ７と蒸発器３の間の冷媒配管に配置される。制御装置１１は第１絞り装置４ａの開度を制御すると共に第２絞り装置４ｂの開度を制御する。他の各機器の動作は実施の形態１と同様である。
【００８５】
第１絞り装置４ａは、第１絞り装置起動運転と第１絞り装置収束制御運転の２種類の制御運転を有する。即ち、第１絞り装置起動運転は、暖房起動後予め設定された時間、数分間の間、定常開度よりも開度の大きい起動開度に設定する制御運転である。この定常開度とは、次の収束制御運転における定常的な開度である。また、第１絞り装置収束制御運転は、例えば図６に示したような第１絞り装置起動運転終了後、圧縮機吐出側の冷媒状態、即ち圧縮機吐出スーパーヒートを予め設定された目標値に収束するように、開度を定常開度から増減して調整する制御運転である。この時の圧縮機吐出スーパーヒートは、例えば温度センサー５３、５４で検知した吐出温度と凝縮温度から演算できる。
第１絞り装置４ａと同様、第２絞り装置４ｂは、第２絞り装置起動運転と第２絞り装置収束制御運転の２種類の制御運転を有する。即ち、第２絞り装置起動運転は、暖房起動後予め設定された時間、数分間の間、定常開度よりも開度の大きい起動開度に設定する制御運転である。この定常開度とは、次の収束制御運転における定常的な開度である。また、第２絞り装置収束制御運転は、第２絞り装置起動運転終了後、凝縮器５の出口側冷媒状態、即ち凝縮器サブクールを予め設定された目標値に収束するように、開度を定常開度から増減して調整する制御運転である。この時の凝縮器サブクールは、例えば温度センサー５４で検知した凝縮温度から演算できる。
【００８６】
ここで、この実施の形態における第１絞り装置４ａと第２絞り装置４ｂの開度制御の一例を図１５の制御フローチャートを用いて説明する。第１絞り装置４ａに関しては実施の形態２で述べたのと同様であり、ここでは第２絞り装置４ｂについて主に説明する。制御装置１４は暖房運転起動指令を受けた（ＳＴ７１）後、第２絞り装置４ｂの開度Ｐ２を起動開度Ｐ２ｓに設定し（ＳＴ７２）、例えば数分の間（ＳＴ７３）、第２絞り装置起動運転（起動ステップ）を行なう。ここで開度Ｐ２ｓは第２絞り装置収束制御運転における定常開度よりも開度を大きく設定する。起動開度Ｐ２ｓで一定時間保留した（ＳＴ７３）後、第２絞り装置収束制御運転（収束ステップ）に移行するため、第２絞り装置４ｂの開度Ｐ２を定常開度Ｐ２ｔｅｉに絞る。ここで、定常開度Ｐ２ｔｅｉは起動開度Ｐ２ｓよりも小さい開度である。
【００８７】
ＳＴ７５で、制御装置１４は収束移行運転（収束移行ステップ）を行う。これは、その時点の圧縮機運転周波数Ｈｚに応じて、第１絞り装置４ａの開度変更量ΔＰ１Ｈｚを算出し、第1絞り装置４ａの開度をＰ１からＰ１＋ΔＰ１Ｈｚにする。即ち、第２絞り装置４ｂを起動開度Ｐ２ｓから定常開度Ｐ２ｔｅｉに絞ることに同期して、第２絞り装置４ｂを絞ったことによる冷媒流量の減少を緩和するように第１絞り装置４ａの開度を増加させる。例えば第１絞り装置４ａを圧縮機運転周波数に応じた開度変更量分ΔＰ１Ｈｚ大きくする。そして、ＳＴ７４、ＳＴ７５で、第１、第２絞り装置４ａ、４ｂの定常開度が設定された後、第１、第２絞り装置を共に収束制御運転する（ＳＴ７６）。
【００８８】
このように制御することにより、第２絞り装置４ｂが起動運転から収束制御運転に移行する際に過渡的に圧縮機１の吸入圧力が低下するのを緩和でき、冷媒循環量の低下による相互弱溶解性油の返油が悪化することを防ぐことができる。従って、十分な圧縮機油量を確保して圧縮機摺動部の潤滑不良による焼付き、異常磨耗などを防止でき、信頼性を向上できる。
【００８９】
例えば、第２絞り装置４ｂの起動開度を定常開度の１．５倍程度とした場合、起動運転から収束制御運転に移行する際、第２絞り装置４ｂの開度は２／３に絞ることになるが、これに同期して、第１絞り装置４ａの開度を増加させる。この増加量は圧縮機周波数に応じて設定されているが、例えば第２絞り装置４ｂで絞った開度の半分程度多く開くようにする。第２絞り装置４ｂを２／３程度に絞ると、過渡的に圧縮機１の吸入圧力が急激に低下するが、第１絞り装置４ａの開度を大きくすることで、冷媒流量の急激な減少を緩和して圧縮機１の吸入圧力が急激に低下するのを防止できる。
【００９０】
実施の形態４．
図１６はこの発明の実施の形態４に係る冷凍サイクル装置の第１絞り装置４ａの制御フローチャートを示す。ここで、冷凍サイクル装置の構成は、実施の形態１〜実施の形態３のいずれかと同様であり、ここではその説明を省略する。この実施の形態は、冷凍サイクル装置として、例えば空気調和装置の暖房暖房停止時の第１絞り装置４ａの開度の制御に関するものであり、例えば暖房運転停止時の制御について、図１６に基づいて説明する。
【００９１】
暖房運転停止指令が指示される（ＳＴ８１）と、圧縮機１及び熱交換器３、５のファンを停止する（ＳＴ８２）。そして、制御装置１１は停止初期制御を行ない、第１絞り装置４ａの開度を停止初期開度Ｐ１ｔｅｉ１に設定する（ＳＴ８３）。この停止初期開度Ｐ１ｔｅｉ１は全閉または非常に小さい開度である。この開度を所定時間、例えば数分程度保持し（ＳＴ８４）、所定時間経過後、停止定常制御に移行して第１絞り装置４ａの開度を停止定常開度Ｐ１ｔｅｉ２になるように大きくする（ＳＴ８５）。
【００９２】
通常は暖房運転停止指令が指示されると、高圧側と低圧側の圧力差が均一になるように、第１絞り装置４ａは全開、またはある程度の開度に保っていた。ところが圧縮機１を停止した時点では、冷凍サイクルには圧力差がついており、高圧側から低圧側に気液ニ相冷媒が急激に流れ込む。低圧側の蒸発器３に気液ニ相冷媒が滞留して停止した状態で、冷凍サイクルを再起動すると、圧縮機１に蒸発器３に滞留していた気液ニ相冷媒が急激に流入することになり、圧縮機１内からは多量の冷凍機油が冷媒回路に吐出されることになる。
【００９３】
そこで、この実施の形態に示すように第１絞り装置４ａの開度を制御して、暖房運転停止時にまず第１絞り装置４ａの開度を全閉または非常に小さい開度である停止初期開度Ｐ１ｔｅｉ１として停止初期運転（停止初期ステップ）を行い、高圧側の液冷媒が差圧によって急激に蒸発器３に流入することを防止する。さらに所定時間後に、開度を開いて停止定常開度Ｐ１ｔｅｉ２に設定して停止定常運転を行うことで、高圧側と低圧側は均圧な状態で停止する。停止初期制御運転を行った後、所定時間保留する間に差圧はある程度小さくなるので、第１絞り装置４ａの開度を停止定常開度Ｐ１ｔｅｉ２になるように大きくしても、高圧側から低圧側に流入する液冷媒の量は、圧縮機１停止と同時に第１絞り装置４ａの開度を停止定常開度Ｐ１ｔｅｉ２に設定するよりも少ない。これにより低圧側である蒸発器３に滞留する液冷媒の量を低減し、運転再起動時に蒸発器３から圧縮機１の吸入側への液バックを低減できる。このため、運転起動時に圧縮機１から液冷媒と共に流出する冷凍機油の量を低減できるので、圧縮機１内に十分な冷凍機油量を確保でき、圧縮機摺動部の潤滑不良による焼付きや異常磨耗などを防止して信頼性を向上できる。
【００９４】
ＳＴ８４における所定時間は、上記では数分程度としたが、これに限るものではない。液冷媒が差圧によって蒸発器３に急激に流入するのを防ぐように、高圧側と低圧側の差圧がある程度小さくなるまでの時間を設定すればよい。
通常、圧縮機１にはその運転条件として再起動禁止時間が設定されており、この再起動禁止時間の範囲で高圧側と低圧側が均圧されるように、かつ、ＳＴ８４における所定時間をできるだけ長く設定すればよい。
なお、ここでは暖房運転停止時の制御について述べたが、蒸発器３を利用して空間の冷房や冷却を行ったりする場合の冷房運転停止時も同様である。
また、この実施の形態に、実施の形態１〜実施の形態３のいずれか１つまたは複数を組み合わせてもよい。
【００９５】
実施の形態５．
図１７はこの発明の実施の形態５に係る制御フローチャートを示す。ここで、冷凍サイクル装置の基本的な構成は、図５と同様である。
この実施の形態による第１絞り装置４ａの開度の制御について、図１７に基づいて説明する。ここで説明する制御処理は、第１絞り装置４ａの開度を起動開度に設定して所定時間運転する第１絞り装置起動運転終了後、吐出温度などを予め設定された目標値に収束するように、開度を定常開度から増減して調整する第１絞り装置収束制御運転に関するものである。暖房運転起動後、第１絞り装置収束制御運転の開始時には、まだ起動後の過渡的な運転であり、第１絞り装置４ａの変化に対しても冷凍サイクルの変化に遅れが発生し、また、吐出温度センサー５３のセンシングに遅れもある。この時に第1絞り装置４ａを必要以上に絞り込んでしまうと、過渡的な吸入圧力低下、冷媒循環量の減少、蒸発温度の低下等が起こる。ここでは、空気調和装置で暖房運転を行う際の第１絞り装置収束制御運転において、第１絞り装置開度変更量ΔＰを制御している。
【００９６】
第１絞り手段収束制御運転において、制御装置１２は第１絞り収束制御運転を開始する（ＳＴ９１）際、吐出温度センサー５３により吐出温度Ｔｄを検知する（ＳＴ９２）。そして、凝縮温度センサ−５４により凝縮温度Ｔｃを検知し（ＳＴ９３）、圧縮機吐出スーパーヒートＳＨｄを計算する（ＳＴ９４）。圧縮機吐出スーパーヒートＳＨｄは吐出温度Ｔｄ−凝縮温度Ｔｃで計算される（圧縮機吐出スーパーヒート検知ステップ）。
第１絞り手段収束制御運転が開始された時点では、気液ニ相状態の冷媒が圧縮機１から吐出されるので、圧縮機吐出スーパーヒートＳＨｄはゼロである。ＳＴ９５で、初めて圧縮機吐出スーパーヒートＳＨｄ＞０になるまで、ＳＴ９７〜ＳＴ９９で、運転中の吐出温度Ｔｄが目標吐出温度Ｔｄｐに近づくように収束制御を行う（収束ステップ）。即ち、吐出温度Ｔｄと目標吐出温度Ｔｄｐとの温度差ΔＴｄを計算する（ＳＴ９７）。そして、この温度差ΔＴｄをゼロにするように第１絞り装置４ａの開度変更量ΔＰ１を計算し（ＳＴ９８）、現在の第1絞り装置４ａの開度を開度変更量ΔＰ１だけ変更した開度Ｐ１（＝Ｐ１＋ΔＰ１）に変更する（ＳＴ９９）。
【００９７】
ＳＴ９７〜ＳＴ９９で、運転中の吐出温度Ｔｄが目標吐出温度Ｔｄｐに近づくように収束制御を行なう（収束ステップ）ことで、第１絞り装置４ａの開度は徐々に絞られ、圧縮機１から吐出される気液ニ相冷媒は乾き度が徐々に高くなる。即ち、第１絞り装置収束制御運転を開始してしばらくの間は、圧縮機吐出スーパーヒートＳＨｄ＝０である。そしてある時点で圧縮機吐出スーパーヒートＳＨｄ＞０となって圧縮機１から吐出される冷媒は過熱ガスとなる。ＳＴ９５の判断では、この過熱ガスが圧縮機１から吐出される時点を圧縮機吐出スーパーヒートＳＨｄの値で検知する。そして、初めて圧縮機吐出スーパーヒートＳＨｄ＞０となった時に、ＳＴ９６で第１絞り装置４ａの開度変更量ΔＰ１をω（ω＞０）に設定（開度増加ステップ）して、現在の第1絞り装置４ａの開度を開度変更量ΔＰ１だけ変更した開度Ｐ１（＝Ｐ１＋ΔＰ１）に変更する（ＳＴ９９）。
【００９８】
ＳＴ９６におけるωは、正の値で、例えば全開の１／２０程度の開度を設定しているが、これに限るものではない。ＳＴ９５の判断において、初めて圧縮機吐出スーパーヒートＳＨｄ＞０にならないときは、ΔＰ１には負の値が設定され、第１絞り装置４ａの開度は絞るように制御されている。初めて圧縮機吐出スーパーヒートＳＨｄ＞０になったときに、ΔＰ１に正の値を設定し、第１絞り装置４ａの開度を一時的に増加させる。
【００９９】
このように、この実施の形態によれば、第１絞り装置収束制御運転で初めて圧縮機吐出スーパーヒートがついたことを検知し、それまで減少していた第１絞り装置４ａの開度を一時的に増加させる。計測した吐出温度Ｔｄに基づいて第１絞り装置４ａの開度Ｐ１の変更を決定しているのであるが、例えば過渡的な温度センシングの遅れなどが生じると、第1絞り装置４ａを必要以上に絞り込むように第１絞り装置４ａの開度Ｐ１が変更される可能性がある。特に圧縮機起動後に最初に圧縮機吐出スーパーヒートがついたことを検知した段階では、すでに第１絞り装置４ａが絞り過ぎの状態となる。この時に、第１絞り装置４ａの開度を一時的に増加することで、第1絞り装置４ａを必要以上に絞り込むのを防止でき、過渡的な吸入圧力低下、冷媒循環量の減少、蒸発温度の低下等が起こるのを防止することができる。従って、十分な油移動速度を確保し、圧縮機１より冷媒回路に流出した弱相互溶解性油が再び圧縮機吸入部に返油されず長時間圧縮機内の油量が減少することを防止でき、圧縮機摺動部の潤滑不良による焼付き、異常磨耗を防止して信頼性を向上できる。
【０１００】
ＳＴ９６で運転起動後初めて圧縮機吐出スーパーヒートがついたことを検知し、それまで減少していた第１絞り装置４ａの開度を一時的に増加させると、圧縮機吐出スーパーヒートがつく前の冷媒状態に戻り、その後、第１絞り装置４ａを吐出温度に基づいて収束させることで、再び圧縮機吐出スーパーヒートがつくことを検知する。この時は、運転起動後初めて圧縮機吐出スーパーヒートがついたのではないので、そのままＳＴ９７、ＳＴ９８で開度変更幅を設定する。
即ち、一度は圧縮機吐出スーパーヒートがつくが、初回の場合には圧縮機１内に必要最低量の冷凍機油が滞留していない可能性が高いので、第１絞り手段４ａの開度の変更量を制御し、圧縮機１内に必要最低量の冷凍機油が滞留してから圧縮機吐出スーパーヒートがつくように運転している。
【０１０１】
また、ＳＴ９５の判断で、検知した圧縮機吐出スーパーヒートが正の値になった時に圧縮機吐出スーパーヒートがついたことを検知したが、計測の誤差を考慮して検知した圧縮機吐出スーパーヒート＞１〜３℃程度となった時に圧縮機吐出スーパーヒートがついたと判断してもよい。
また、図１７の制御フローチャートでは第１絞り装置４ａの開度を一時的に増加させるために、開度変更量ΔＰ１にω（ω＞０）を設定したが、一時的に目標吐出温度Ｔｄｐを下げることで第１絞り装置４ａの開度を一時的に増加させてもよい。
また、開度変更量ωを外気温度や蒸発温度に対応して設定してもよい。この場合、外気温度や蒸発温度が低い場合には、高い場合に比べて開度変更量ωを大きく設定すればよい。
【０１０２】
また、図１７に示す収束制御では吐出温度が目標温度になるように第１絞り装置４ａの開度を制御しているが、吐出温度の代わりに、圧縮機吐出スーパーヒートによって冷媒状態を目標状態に近づくように第１絞り装置４ａの開度を制御してもよい。
また、吐出温度センサー５３と凝縮温度センサー５４で検知した吐出温度と凝縮温度とから圧縮機吐出スーパーヒートを検知しているが、他の検知手段で検知するようにしてもよい。
また、この実施の形態に、実施の形態１〜実施の形態４のいずれか１つまたは複数を組み合わせてもよい。
【０１０３】
実施の形態１〜実施の形態５のいずれかにおいて、冷凍サイクルの冷媒として、ＨＦＣ冷媒、例えばＲ３２、Ｒ１３４ａ、Ｒ４１０Ａ，Ｒ４０７Ｃ、Ｒ４０７Ｅ、Ｒ４０４Ａなど、または自然冷媒、例えばＲ２９０、Ｒ６００ａなどのＨＣ冷媒や、Ｒ７４４、二酸化炭素、水、空気、アンモニアなどを用いると、オゾン層破壊など地球環境に悪影響を与えず、地球環境を保全できる冷凍サイクル装置を提供できる。
【０１０４】
また、冷凍サイクル装置で使用する冷凍機油としては、上記の冷媒に弱相溶解性を示すものなら何でもよいが、安定性の点から動粘度８〜３２ｃＳｔのアルキルベンゼン系油を用いるのが好ましい。
冷媒に対して弱相溶解性の冷凍機油は、非常に安定性が高く、不純物の混入に対して劣化が少なく、このために既設配管を使えるなど、多大な利点がある。例えば、冷媒に対して弱相互溶解性のアルキルベンゼン油は、非常に安定性が高い油として知られており、水分などの異物が混入しても分解することなくスラッジの発生により冷媒回路が閉塞したりする危険性が小さい。このため、設置工事などの際、異物が混入してもシステムに故障を起こす危険性が少なく高い信頼性を確保することができる。
また、動粘度８〜３２ｃＳｔの弱溶解性油は通常の空気調和機の使用温度範囲において十分な流動性を有しており、圧縮機シェル内の油枯渇を防止し圧縮機摺動部の潤滑不良による焼付き、異常磨耗などを防止でき、信頼性の向上を図ることができる。
【０１０５】
冷凍サイクルに充填される冷媒の量が、冷凍機油の量に比べて、例えば３倍程度に多くなると、暖房起動時に圧縮機１に吸入される液冷媒量が多くなり、圧縮機１から流出する冷凍機油の量が多くなる。従って、実施の形態１〜実施の形態５のそれぞれを適用することで、さらにこの発明のそれぞれの効果が有効となる。冷凍サイクル装置に、冷凍機油の量に比べて例えば３倍程度以上に多くなる冷媒の量を予め充填しておくと、設置場所が広い範囲でも対応でき、さらに据え付け時にその場所に応じた作業工程を少なくできる。また、液溜め手段であるレシーバは必ずしも設けなくてもよいが、レシーバを備えていると、冷房機能と暖房機能を有する空気調和装置などで運転によって生じる余剰冷媒を貯留できるので、効率良く運転できる。
【０１０６】
実施の形態１〜実施の形態５のそれぞれにおいては空気調和装置について説明したが、この発明のそれぞれは空気調和装置に限るものではなく、冷凍機や冷凍冷蔵庫などの冷凍サイクル装置にも適用でき、同様の効果を奏する。
【０１０７】
【発明の効果】
以上説明したように、この発明の冷凍サイクル装置によれば、圧縮機、凝縮器、絞り手段、蒸発器を接続して冷媒を循環させる冷媒回路を有し、前記冷媒に対して弱相互溶解性の冷凍機油を用いた冷凍サイクルと、前記蒸発器の周辺温度を検知する温度センサーと、前記蒸発器の周辺温度に対応して設定された複数の圧縮機最低運転周波数の中より前記温度センサーの検出した温度に対応した圧縮機最低運転周波数を設定し、前記圧縮機最低運転周波数以上となる周波数で前記圧縮機を運転制御する制御手段と、を備えたことにより、長時間圧縮機内の冷凍機油量が減少することを防止でき、信頼性を向上できる効果がある。
【０１０８】
また、この発明の冷凍サイクル装置によれば、前記制御手段は、前記温度センサーで検知した温度に対して前記圧縮機から流出した冷凍機油を予め設定した時間内で前記圧縮機に返油し得る圧縮機最低周波数を決定し、前記圧縮機を前記圧縮機最低周波数以上の周波数で制御することにより、長時間圧縮機内の冷凍機油量が減少することを確実に防止でき、信頼性を向上できる効果がある。
【０１０９】
また、この発明の冷凍サイクル装置によれば、前記制御手段は、複数の蒸発器周辺温度のそれぞれに対し、前記圧縮機から流出した冷凍機油が予め設定した時間内で前記圧縮機へ返油し得る圧縮機最低運転周波数を記憶する記憶部と、前記記憶部に記憶した前記圧縮機最低運転周波数のデータに基づき、前記温度センサーで検知した温度に対して前記時間内で前記圧縮機へ返油し得る圧縮機最低運転周波数を演算する演算部と、前記演算部で得られた圧縮機最低運転周波数以上の周波数で前記圧縮機を運転する制御部と、を備えたことにより、長時間圧縮機内の冷凍機油量が減少することを確実に防止でき、信頼性を向上できる効果がある。
【０１１０】
また、この発明の冷凍サイクル装置によれば、前記蒸発器の周辺温度を検知する温度センサーと、前記圧縮機吐出側の冷媒状態を検知する冷媒状態検知手段と、を備え、前記制御手段は、前記温度センサーで検知した蒸発器周辺温度と前記圧縮機の運転周波数に対して、前記冷媒状態検知手段で検知した前記圧縮機吐出側の冷媒状態が目標状態に安定すると推定される前記絞り手段の開度を最低開度に設定し、前記絞り手段を前記最低開度より大きな開度で制御することにより、長時間圧縮機内の冷凍機油量が減少することを確実に防止でき、信頼性を向上できる効果がある。
【０１１１】
また、この発明の冷凍サイクル装置によれば、前記蒸発器の周辺温度を検知する温度センサーを備え、前記制御手段は、前記絞り手段の起動開度を前記温度センサーで検知した蒸発器周辺温度に対して予め設定された時間内で返油し得る開度に設定して絞り手段起動運転を開始することにより、起動運転で長時間圧縮機内の冷凍機油が減少することを確実に防止でき、信頼性を向上できる効果がある。
【０１１２】
また、この発明の冷凍サイクル装置によれば、圧縮機、凝縮器、絞り手段、蒸発器を接続して冷媒を循環させる冷媒回路を有し、前記冷媒に対して弱相互溶解性の冷凍機油を用いた冷凍サイクルと、蒸発器周辺温度または圧縮機シェル温度を検知する温度センサーと、前記温度センサーで検知した蒸発器周辺温度または圧縮機シェル温度に対して、前記圧縮機内に前記圧縮機の必要最低量の冷凍機油を滞留させてから前記圧縮機の出口で圧縮機吐出スーパーヒートがつくように、前記絞り手段の開度の変更量または前記絞り手段の絞り開始時期を制御する制御手段と、を備えたことにより、圧縮機内の冷凍機油量が減少することを防止でき、信頼性を向上できる効果がある。
【０１１３】
また、この発明の冷凍サイクル装置によれば、前記圧縮機出口側の冷媒状態を検知する冷媒状態検知手段を備え、前記制御手段は、前記絞り手段を圧縮機運転周波数に応じた起動開度に設定して運転する絞り手段起動運転と、前記絞り手段起動運転の後に、前記冷媒状態検知手段で検知した圧縮機吐出側の冷媒状態が目標状態に近づくように前記絞り手段の開度を増減させる絞り手段収束制御運転と、を行なうと共に、前記蒸発器周辺温度が低いときの前記絞り手段起動運転の時間を前記蒸発器周辺温度が高いときの前記絞り手段起動運転の時間より長くしたことにより、圧縮機内の冷凍機油量が減少することを確実に防止でき、信頼性を向上できる効果がある。
【０１１４】
また、この発明の冷凍サイクル装置によれば、前記圧縮機出口側の冷媒状態を検知する冷媒状態検知手段を備え、前記制御手段は、前記絞り手段を圧縮機運転周波数に応じた起動開度に設定して運転する絞り手段起動運転と、前記絞り手段起動運転の後に、前記冷媒状態検知手段で検知した圧縮機吐出側の冷媒状態が目標状態に近づくように前記絞り手段の開度を増減させる絞り手段収束制御運転と、を行なうと共に、前記シェル温度が高いときの前記絞り手段起動運転の時間を前記シェル温度が低いときの前記絞り手段起動運転の時間より短くしたことにより、圧縮機内の冷凍機油量が減少することを確実に防止でき、効率良く運転できると共に信頼性を向上できる効果がある。
【０１１５】
また、この発明の冷凍サイクル装置によれば、前記圧縮機出口側の冷媒状態を検知する冷媒状態検知手段を備え、前記制御手段は、前記絞り手段を圧縮機運転周波数に応じた起動開度に設定する絞り手段起動運転と、前記絞り手段起動運転の後に、前記冷媒状態検知手段で検知した圧縮機吐出側の冷媒状態が目標状態に近づくように前記絞り手段の開度を増減させる絞り手段収束制御運転と、を行なうと共に、前記絞り手段収束制御運転における蒸発器周辺温度が低いときの最大開度変更量を前記蒸発器周辺温度が高いときの最大開度変更量より小さく設定したことにより、圧縮機内の冷凍機油量が減少することを確実に防止でき、信頼性を向上できる効果がある。
【０１１６】
また、この発明の冷凍サイクル装置によれば、圧縮機、凝縮器、絞り手段、蒸発器を接続して冷媒を循環させる冷媒回路を有し、前記冷媒に対して弱相互溶解性の冷凍機油を用いた冷凍サイクルと、前記圧縮機出口側の圧縮機吐出スーパーヒートを検知する圧縮機吐出スーパーヒート検知手段と、前記圧縮機吐出スーパーヒート検知手段で運転起動後に初めて圧縮機吐出スーパーヒートがついたことを検知した時に前記絞り手段の開度を増加させる制御手段と、を備えたことにより、圧縮機内の冷凍機油量が減少することを確実に防止でき、信頼性を向上できる効果がある。
【０１１７】
また、この発明の冷凍サイクル装置によれば、圧縮機、凝縮器、絞り装置、蒸発器を順次接続して冷媒を循環させる冷媒回路を有し、前記冷媒に対して弱相互溶解性の冷凍機油を用いた冷凍サイクルにおいて、運転停止時に、前記絞り装置の開度を停止初期開度に設定する停止初期運転と、前記停止初期運転の後に前記絞り装置の開度を前記停止初期開度よりも大きく設定する停止定常運転と、を行なう制御手段を備えたことにより、起動時の蒸発器から圧縮機吸入側への液バック量を減少して圧縮機から流出する冷凍機油量を低減し、圧縮機内の冷凍機油量を確保でき、信頼性を向上できる効果がある。
【０１１８】
また、この発明の冷凍サイクル装置によれば、圧縮機、蒸発器、第１絞り手段、液溜め手段、第２絞り手段、凝縮器を順次接続して冷媒を循環させる冷媒回路を有し、前記冷媒に対して弱相互溶解性の冷凍機油を用いた冷凍サイクルにおいて、前記第２絞り手段の開度を第２絞り手段の起動開度に設定する第２絞り手段起動運転と、前記第２絞り手段起動運転の後に前記第２絞り手段を前記起動開度よりも小さい定常開度に設定すると共に、前記第１絞り手段の開度を所定開度大きくする収束移行運転と、前記収束移行運転の後に前記第２絞り手段の開度を増減して前記凝縮器の出口側の冷媒状態を制御する第２絞り手段収束制御運転と、を行なう制御手段を備えたことにより、第２絞り手段が起動運転から定常制御運転に移行する際に過渡的に圧縮機吸入圧力が低下するのを防止し、十分な圧縮機油量を確保でき、信頼性を向上できる効果がある。
【０１１９】
また、この発明の冷凍サイクル装置によれば、冷凍サイクル内に液溜め手段を備えると共に、冷凍機油量に対して３倍以上の冷媒量を封入したことにより、据え付け工程が容易にでき、かつ、圧縮機内の冷凍機油量が減少することを防止でき、信頼性を向上できる効果がある。
【０１２０】
また、この発明の冷凍サイクル装置によれば、冷媒は、ＨＦＣ冷媒または自然冷媒を用いることにより、オゾン層破壊など地球環境への悪影響を低減し、地球環境を保全できる効果がある。
【０１２１】
また、この発明の冷凍サイクル装置によれば、冷凍機油は、動粘度８〜３２ｃＳｔのアルキルベンゼン系油を用いることにより、劣化しにくく安定性が高く使用温度範囲で十分な流動性を有する冷凍機油を用い、信頼性を向上できる効果がある。
【０１２２】
また、この発明の冷凍サイクル装置の制御方法によれば、圧縮機の周波数を徐々に上げ、前記周波数に伴って絞り手段の開度を起動開度に設定する起動ステップと、前記圧縮機が負荷に応じた所定の回転数に達した後に前記絞り手段の開度を前記起動開度よりも小さく絞って増減させ、圧縮機出口側の冷媒状態を目標状態に近づける絞り手段収束ステップと、蒸発器周辺温度または圧縮機シェル温度に対して、前記起動ステップの運転時間または前記絞り手段収束ステップの前記絞り手段の開度増減幅を制御する収束時間制御ステップと、を備えたことにより、圧縮機内の冷凍機油量が減少することを防止し、信頼性を向上できる効果がある。
【０１２３】
また、この発明の冷凍サイクル装置の制御方法によれば、圧縮機の運転を停止する圧縮機停止ステップと、前記圧縮機停止ステップの後に絞り手段の開度を停止初期開度に設定する停止初期ステップと、前記停止初期ステップの後に前記絞り手段の開度を前記停止初期開度よりも大きく設定する停止定常ステップと、を備えたことにより、起動時の蒸発器から圧縮機吸入側への液バック量を減少しして圧縮機から流出する冷凍機油量を低減し、圧縮機内の冷凍機油量を確保でき、信頼性を向上できる効果がある。
【０１２４】
また、この発明の冷凍サイクル装置の制御方法によれば、冷媒貯溜手段の上流側絞り手段を起動開度に設定して運転する上流側絞り手段起動ステップと、前記上流側絞り手段起動ステップの後に前記上流側絞り手段の開度を増減させて凝縮器出口側の冷媒状態を目標状態に近づける上流側絞り手段収束ステップと、前記上流側絞り手段起動ステップから前記上流側絞り手段収束ステップに移るときの前記上流側絞り手段の開度の減少による冷媒流量の減少を緩和するように前記冷媒貯溜手段の下流側絞り手段の開度を増加させる収束移行ステップと、を備えたことにより、を備えたことにより、第２絞り手段が起動運転から定常制御運転に移行する際に過渡的に圧縮機吸入圧力が低下するのを防止し、圧縮機内に十分な冷凍機油量を確保でき、信頼性を向上できる効果がある。
【０１２５】
また、この発明の冷凍サイクル装置の制御方法によれば、圧縮機吐出スーパーヒートを検知する圧縮機吐出スーパーヒート検知ステップと、前記圧縮機吐出スーパーヒート検知ステップで初めて前記圧縮機吐出スーパーヒートがついたことを検知したときに絞り手段の開度を増加させる開度増加ステップと、前記絞り手段の開度を増減させて圧縮機出口側の冷媒状態を目標状態に近づける絞り手段収束ステップと、を備えたことにより、圧縮機内に十分な冷凍機油量を確実に確保でき、信頼性を向上できる効果がある。
【図面の簡単な説明】
【図１】 この発明の実施の形態1に係る冷凍サイクル装置を示す構成図である。
【図２】 実施の形態１に係る制御フローチャートである。
【図３】 実施の形態１に係り、外気温度に対する冷媒流量と返油時間の関係を示すグラフである。
【図４】 実施の形態１に係る制御装置の構成を示すブロック図である。
【図５】 実施の形態１に係る冷凍サイクル装置の他の構成例を示す構成図である。
【図６】 実施の形態１の他の構成例に係る制御フローチャートである。
【図７】 この発明の実施の形態２に係る冷凍サイクル装置を示す構成図である。
【図８】 実施の形態２に係る制御フローチャートである。
【図９】 実施の形態２に係り、外気温度に対して同じ返油時間を確保するのに必要な冷媒流量を示すグラフである。
【図１０】 実施の形態２の他の構成例に係る制御フローチャートである。
【図１１】 実施の形態２に係り、冷媒流量に対する外気温度と返油時間の関係を示すグラフである。
【図１２】 実施の形態２のさらに他の構成例に係る制御フローチャートである。
【図１３】 実施の形態２のさらに他の構成例に係る制御フローチャートである。
【図１４】 この発明の実施の形態３に係る冷凍サイクル装置を示す構成図である。
【図１５】 実施の形態３に係る制御フローチャートである。
【図１６】 この発明の実施の形態４に係る制御フローチャートである。
【図１７】 この発明の実施の形態５に係る制御フローチャートである。
【符号の説明】
1 圧縮機、２ 四方弁、３ 蒸発器、４ 絞り装置、４ａ 第１絞り手段（下流側絞り手段）、４ｂ 第２絞り手段（上流側絞り手段）、５ 凝縮器、７ 液溜め手段、９ 吸入配管、１１、１２、１３、１４ 制御手段、５１ 外気温度センサー、５２ 室内温度センサー、５３ 吐出温度センサー、５４ 凝縮温度センサー、５５ 圧縮機シェル温度センサー。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigeration cycle apparatus using a refrigeration cycle such as an air conditioner and a control method for the refrigeration cycle apparatus.
[0002]
[Prior art]
In a conventional refrigeration cycle apparatus such as an air conditioner, an HFC refrigerant is sealed as a refrigerant, and mineral oil or alkylbenzene oil weakly soluble in the HFC refrigerant is used as a refrigeration oil filled in a compressor. In this case, there arises a problem that the oil return performance of the refrigerating machine oil flowing out from the compressor is poor. Therefore, in a conventional refrigeration system, for example, when the cooling load is small and the compressor needs to be continuously operated at a low rotation speed, the compressor is operated at a high speed for a predetermined time to return the refrigeration oil to the compressor. (For example, refer to Patent Document 1).
[0003]
[Patent Document 1]
JP 2001-208435 A (4th page, FIG. 3)
[0004]
[Problems to be solved by the invention]
In a conventional refrigeration apparatus using weakly soluble refrigeration oil, the compressor is operated at a high rotational speed for a predetermined time only when the compressor is continuously operated at a low rotational speed. However, when heating operation is performed with an air conditioner or the like as a refrigeration cycle device, for example, in a high-pressure gas pipe connecting a compressor and a condenser and a low-pressure gas pipe connecting an evaporator and a compressor, gas refrigerant is almost free from refrigeration oil Does not dissolve. For this reason, the kinematic viscosity of the refrigerating machine oil hardly flows back because it flows in the refrigerant circuit in a state equivalent to the kinematic viscosity of the pure refrigerating machine oil. In addition, a problem arises particularly when the operation is started in a state where the outside air temperature is low. When the operation is started at a low outside air temperature, the amount of refrigeration oil dissolved in the refrigerant decreases due to a decrease in the evaporation temperature, and the kinetic viscosity of the refrigeration oil further increases. The oil return performance to the compressor deteriorates. As a result, there is a problem that the operation is hindered, such as seizure due to poor lubrication of the compressor sliding portion and abnormal wear due to insufficient refrigerating machine oil in the compressor.
[0005]
In addition, when the refrigeration cycle apparatus that is stopped in a state where a large amount of two-phase refrigerant is accumulated in the evaporator when the operation of the refrigeration cycle apparatus is stopped, the two-phase refrigerant that has accumulated in the evaporator flows into the compressor. Then, it is compressed and discharged from the discharge pipe as a high-temperature and high-pressure two-phase refrigerant. A part of the liquid refrigerant in the high-temperature and high-pressure two-phase refrigerant is not discharged from the compressor and is discharged to the bottom of the compressor shell. Accumulate. Weakly soluble oil is pushed up above the liquid refrigerant having a large specific gravity and tends to flow out from the discharge pipe to the refrigeration cycle, resulting in a problem that the compressor oil in the compressor is insufficient.
[0006]
This invention was made to solve the above problems, and in a refrigeration cycle using a refrigerating machine oil that is weakly soluble in a refrigerant, particularly during operation when the ambient temperature of the evaporator is low, An object of the present invention is to obtain a highly reliable refrigeration cycle apparatus by reliably returning refrigeration oil to the compressor.
Another object of the present invention is to obtain a highly reliable refrigeration cycle apparatus by reducing liquid back to the compressor when the refrigeration cycle apparatus is started.
[0010]
The refrigeration cycle apparatus according to the present invention includes a temperature sensor that detects the ambient temperature of the evaporator, and a refrigerant state detection unit that detects a refrigerant state on the compressor discharge side, and the control unit includes With respect to the evaporator ambient temperature detected by the temperature sensor and the operating frequency of the compressor, the opening of the throttle means that is estimated that the refrigerant state on the compressor discharge side detected by the refrigerant state detection means is stabilized in the target state. The degree is set to a minimum opening, and the throttle means is controlled to an opening larger than the minimum opening.
[0011]
  Further, the refrigeration cycle apparatus according to the present invention is a temperature sensor for detecting the ambient temperature of the evaporator.-And the control means sets the starting opening of the throttle means to an opening that can return oil within a preset time with respect to the evaporator ambient temperature detected by the temperature sensor, and performs throttle means starting operation. It is characterized by starting.
[0016]
[Means for Solving the Problems]
  A refrigeration cycle apparatus according to the present invention has a refrigerant circuit that connects a compressor, a condenser, a throttle means, and an evaporator to circulate the refrigerant, and uses a refrigeration oil that is weakly soluble in the refrigerant. The compressor discharge superheat detection means for detecting the compressor, the compressor discharge superheat on the compressor outlet side, and the compressor discharge superheat detection means detects that the compressor discharge superheat has been applied for the first time after the start of operation. And a control means for increasing the opening of the throttle means.
[0018]
The refrigeration cycle apparatus according to the present invention further includes a refrigerant circuit for circulating a refrigerant by sequentially connecting a compressor, an evaporator, a first throttling means, a liquid storage means, a second throttling means, and a condenser. In the refrigeration cycle using weakly soluble refrigerating machine oil, the second throttle means starting operation for setting the opening degree of the second throttle means to the startup opening degree of the second throttle means, and the second throttle means After the start-up operation, the second throttle means is set to a steady opening smaller than the start-up opening, and the convergence transition operation in which the opening degree of the first throttle means is increased by a predetermined opening, and after the convergence transition operation Control means for performing a second throttle means convergence control operation for controlling the refrigerant state on the outlet side of the condenser by increasing or decreasing the opening degree of the second throttle means.
[0019]
In addition, the refrigeration cycle apparatus according to the present invention is characterized in that the refrigeration cycle is provided with a liquid storage means and a refrigerant amount three times or more the amount of the refrigerating machine oil is enclosed.
[0020]
In the refrigeration cycle apparatus according to the present invention, the refrigerant is an HFC refrigerant or a natural refrigerant.
[0021]
In the refrigeration cycle apparatus according to the present invention, the refrigerating machine oil is an alkylbenzene oil having a kinematic viscosity of 8 to 32 cSt.
[0022]
Further, the control method of the refrigeration cycle apparatus according to the present invention includes a startup step of gradually increasing the frequency of the compressor and setting the opening of the throttle means to the startup opening according to the frequency, and the compressor is loaded. A throttle means converging step for reducing the opening degree of the throttle means to be smaller than the starting opening degree after reaching a predetermined number of revolutions, and bringing the refrigerant state on the compressor outlet side closer to the target state; and around the evaporator A convergence time control step for controlling an operating time of the start-up step or an opening / closing increase / decrease width of the throttle means in the throttle means convergence step with respect to temperature or compressor shell temperature.
[0024]
Further, the control method of the refrigeration cycle apparatus according to the present invention includes an upstream side throttle means starting step in which the upstream side throttle means of the refrigerant storage means is set to the start opening, and an operation after the upstream side throttle means starting step. An upstream throttle means convergence step for increasing or decreasing the opening degree of the upstream throttle means to bring the refrigerant state on the outlet side of the condenser closer to the target state, and a transition from the upstream throttle means activation step to the upstream throttle means convergence step. A convergence transition step of increasing the opening degree of the downstream throttle means of the refrigerant storage means so as to alleviate the decrease in the refrigerant flow rate due to the reduction of the opening degree of the upstream throttle means.
[0025]
In the control method of the refrigeration cycle apparatus according to the present invention, the compressor discharge superheat detection step for detecting the compressor discharge superheat, and the compressor discharge superheat for the first time in the compressor discharge superheat detection step are attached. An opening increasing step for increasing the opening of the throttle means when detecting this, and a throttle means convergence step for increasing or decreasing the opening of the throttle means to bring the refrigerant state on the compressor outlet side closer to the target state. It is a thing.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing, for example, a refrigeration cycle of an air conditioner as a refrigeration cycle apparatus according to Embodiment 1 of the present invention. FIG. 2 is a control flowchart of the compressor operating frequency according to this embodiment, and FIG. 3 shows the relationship between the refrigerant flow rate and the oil return time with respect to the outside air temperature according to this embodiment.
[0027]
In FIG. 1, a compressor 1, a heat exchanger 3 operating as an evaporator during heating, and a condenser during cooling, a first throttle device 4a as a first throttle means, a receiver 7 as a liquid reservoir means, a second throttle, and the like. For example, the second expansion device 4b, a heat exchanger 5 that operates as a condenser during heating, and an evaporator during cooling, and a flow path switching unit that switches the refrigerant circulation direction between the heating operation and the cooling operation, such as a four-way valve 2, are provided. The refrigeration cycle is configured by connecting with piping.
The refrigeration cycle apparatus in FIG. 1 shows a state during heating operation of the air conditioner, for example, as a refrigeration cycle apparatus. In this embodiment, for example, the heat exchanger 3 is an outdoor heat exchanger installed outdoors. A description will be given of a case where the indoor heating operation is performed by operating the heat exchanger 5 as an evaporator and the heat exchanger 5 as a condenser as an indoor heat exchanger in which the heat exchanger 5 is installed indoors.
[0028]
Depending on the distance between the place where the outdoor heat exchanger 3 is installed and the place where the indoor heat exchanger 5 is installed, the length of the refrigerant pipe constituting the refrigeration cycle differs, and the amount of refrigerant charged differs depending on the length of the refrigerant pipe. For example, in the refrigeration cycle shown in FIG. 1, an extension pipe is connected between the pipe A and the pipe B and between the pipe C and the pipe D. Also, the required amount of refrigerant circulating in the refrigeration cycle differs depending on the heating operation, the cooling operation, and the load. The receiver 7, which is a liquid storage means, is a container for storing excess refrigerant, and is a container for retaining excess refrigerant so that an optimum amount of refrigerant circulates in the refrigeration cycle depending on the operation, load, and length of the extension pipe. is there. The first expansion device 4a is, for example, an electronic expansion valve provided in a refrigerant pipe between the outdoor heat exchanger 3 and the receiver 7, and the flow rate of the refrigerant flowing through the pipe can be varied by changing the opening degree. Similarly, the second expansion device 4b is an electronic expansion valve provided, for example, in a refrigerant pipe between the indoor heat exchanger 5 and the receiver 7, and the flow rate of the refrigerant flowing through the pipe is variable by changing the opening degree. Can be.
[0029]
The outdoor temperature sensor 51 can detect the temperature around the outdoor heat exchanger 3 that operates as an evaporator, for example, the outside air temperature, and the indoor temperature sensor 52 can detect the temperature around the indoor heat exchanger 5, such as the room temperature. . For example, the control device 11 serving as the control means is configured as shown in the block diagram of FIG. 4. For example, the microcomputer includes a measurement temperature input unit 11 a, a storage unit 11 b, and an arithmetic processing unit 11 c from the temperature sensors 51 and 52. And the compressor drive circuit 11d, which controls the frequency of the compressor 1 based on the temperatures detected by the temperature sensors 51 and 52.
[0030]
The refrigerant used in this refrigeration cycle is an HFC refrigerant, for example, R410A, which is a mixed refrigerant of R32 and R125, and the refrigeration oil is weakly soluble in the refrigerant, such as alkylbenzene oil, and has an oil specific gravity of liquid refrigerant. Use refrigeration oil smaller than specific gravity. Weakly soluble refrigerating machine oil has many advantages, such as being able to maintain stability without being deteriorated even if some impurities are mixed, and using existing piping.
[0031]
Next, in the air conditioner configured as described above, the operation at the initial stage of the heating operation will be described. After the heating operation is started, the compressor 1 sucks and compresses the two-phase refrigerant accumulated in the outdoor heat exchanger 3 from the suction pipe and discharges it from the discharge pipe as a high-temperature and high-pressure two-phase refrigerant. A part of the liquid refrigerant in the high-temperature and high-pressure two-phase refrigerant after compression is not discharged from the compressor 1 and accumulates at the bottom of the compressor shell. The weakly soluble oil sealed in the compressor 1 is pushed up above the liquid refrigerant having a large specific gravity and flows out from the discharge pipe to the refrigeration cycle. Note that the amount of weakly soluble oil that flows out of the compressor 1 varies depending on the amount of refrigerant enclosed. If the place where the heat exchangers 3 and 5 are installed is long, the extension pipe becomes long and the required amount of refrigerant increases. However, the amount of refrigerant oil filled hardly changes, so the amount of refrigerant is equal to the amount of refrigerant oil. May be more than three times. In particular, in such a system in which the amount of refrigerant filled is more than three times the amount of refrigeration oil, the amount of weakly soluble oil that flows out is extremely large.
[0032]
The high-temperature and high-pressure two-phase refrigerant discharged from the compressor 1 passes through the four-way valve 2 and enters the indoor heat exchanger 5 to exchange heat with room air, and is condensed to a two-phase refrigerant or liquid refrigerant having a low dryness. It flows out of the heat exchanger 5. The two-phase refrigerant or liquid refrigerant having a low dryness flowing out from the indoor heat exchanger 5 is reduced to an intermediate pressure through the second expansion device 4b and flows into the receiver 7 as a two-phase refrigerant having a low dryness. The low-dryness two-phase refrigerant flowing into the receiver 7 exchanges heat with the low-pressure and low-temperature suction pipe 9 connected to the suction side of the compressor 1 inserted in the receiver 7. Then, it becomes a two-phase refrigerant or a saturated liquid refrigerant having a smaller dryness and flows out from the receiver 7. The two-phase refrigerant or saturated liquid refrigerant having a low dryness flowing out from the receiver 7 passes through the first expansion device 4a to become a low-pressure two-phase refrigerant and flows into the outdoor heat exchanger 3.
[0033]
The low-pressure two-phase refrigerant that has flowed into the outdoor heat exchanger 3 exchanges heat with the outside air to become a low-pressure two-phase refrigerant having a high degree of dryness and flows out of the outdoor heat exchanger 3. The low-pressure two-phase refrigerant having a high dryness flowing out from the outdoor heat exchanger 3 passes through the suction pipe 9 inserted in the receiver 7 and exchanges heat with the intermediate-pressure refrigerant in the receiver 7. Then, the refrigerant becomes a low-pressure two-phase refrigerant having a higher dryness and returns to the suction side of the compressor 1 through the four-way valve 2.
[0034]
On the other hand, the weakly soluble oil discharged from the compressor 1 returns to the suction side of the compressor 1 again through the same path as the refrigerant described above.
[0035]
As described above, at the initial stage of heating operation, weakly soluble oil sealed in the compressor 1 is pushed up by the liquid refrigerant and flows out into the refrigerant circuit, so that the amount of refrigerating machine oil in the compressor 1 is reduced and compressed. There was a possibility that reliability such as seizure and abnormal wear due to poor lubrication of the machine sliding part could be reduced. In particular, since weakly soluble oil has low refrigerant solubility, the oil kinematic viscosity does not decrease, and in the case of heating operation, the evaporation temperature becomes low and the oil kinematic viscosity increases in the evaporator 3 and the low-pressure gas pipe. For this reason, it takes a long time for the weakly soluble oil that has once flown out of the compressor 1 to return to the suction portion of the compressor 1 to recover the amount of refrigeration oil in the compressor 1. .
[0036]
FIG. 3 shows the refrigerant flow rate (kg) obtained by the experiment when the extension pipe (the pipe length between A and B in FIG. 1 and between C and C) is 50 m and the number of passes of the evaporator 3 is 4 passes. / H) is a graph showing the relationship between the oil return time (sec), the horizontal axis indicates the refrigerant flow rate (kg / h), and the vertical axis indicates the oil return time (sec). Here, the oil return time is the time from when the refrigeration oil is discharged from the compressor 1 until it is returned to the compressor 1. The three curves show the relationship when the outside air temperature is −10 ° C., 0 ° C., and 7 ° C. from the upper side. It can be seen that the lower the outside air temperature, the higher the kinematic viscosity of the oil and the longer the oil return time, even at the same refrigerant flow rate.
[0037]
Here, an example of the control of the compressor operating frequency according to this embodiment will be described based on the control flowchart shown in FIG. When receiving the heating operation start command (ST1), the control device 11 performs the compressor start operation (ST2). This is, for example, an operation in which the frequency of the compressor 1 is gradually increased from a stopped state, and after about several minutes, the frequency is increased or decreased according to the load in a steady operation. Thereafter, the set room temperature Tainset set by the remote controller or the like is read (ST3). The outside air temperature Tao at the time of start-up is detected by the outside air temperature sensor 51 (ST4), and the minimum refrigerant flow rate Gmin necessary for satisfying a preset oil return time is set (ST5). This can be set from the relationship between the refrigerant flow rate and the oil return time at the outside air temperature Tao shown in FIG. Next, the compressor minimum operation frequency Hzmin is set so that the minimum refrigerant flow rate Gmin is obtained (ST6). For example, if the required oil return time is 10 minutes, it is about 60 (kg / h) when the outside air temperature is −10 ° C., about 45 (kg / h) when it is 0 ° C., and 35 (kg / h) when it is 7 ° C. The compressor frequency that is about the same is set as the minimum operating frequency Hzmin.
[0038]
Next, the room temperature Tain is detected by the room temperature sensor 52 (ST7), and the change amount ΔHz of the compressor operating frequency is calculated according to the difference (Tainset−Tain) from the set room temperature Tainset (ST8). The frequency Hz = Hz + ΔHz is calculated (ST9). It is determined whether or not the compressor operating frequency Hz calculated here is smaller than the compressor minimum operating frequency Hzmin (ST10). If it is determined that the compressor operating frequency Hz <the compressor minimum operating frequency Hzmin, the compressor operating frequency is determined. The frequency Hz is set as the minimum compressor operating frequency Hzmin (ST11). Control of ST7-ST11 is performed during heating operation.
[0039]
In this way, in the control process shown in FIG. 2, the lower limit value of the compressor operating frequency Hz is provided, and the operation is performed so that the refrigerant flow rate does not fall below the minimum refrigerant flow rate that satisfies the preset oil return time. The minimum refrigerant flow rate is a minimum value of the refrigerant flow rate at which the refrigeration oil flowing out from the compressor 1 is returned to the compressor 1 in a predetermined time, for example, about 10 minutes. In the compressor 1, the necessary minimum amount of refrigeration oil is usually determined in advance at the liquid level. If the amount of the refrigeration oil in the compressor 1 falls below this liquid level, the operation is hindered. The oil return time is set so that at least the amount of refrigerating machine oil staying in the compressor 1 is returned to the compressor 1 before the amount of oil does not fall below the required minimum oil amount. By ensuring the flow rate of the refrigerant circulating in the refrigeration cycle in this way, the weakly soluble refrigerant oil that has flowed out of the compressor 1 into the refrigerant circuit is returned to the compressor suction portion again within a predetermined time, and the compressor It is possible to prevent the amount of refrigeration oil in 1 from being reduced for a long time. Therefore, seizure or abnormal wear due to poor lubrication of the sliding portion of the compressor can be prevented, and reliability can be improved.
Note that the minimum required amount of refrigerating machine oil determined in advance in the compressor 1 is determined as the liquid level height, and the required minimum oil amount is reached with the liquid refrigerant in the lower part of the refrigerating machine oil in the compressor 1. Even if it is, depending on the amount of the liquid refrigerant, the compressor 1 may be able to be operated without any problem.
[0040]
Further, in the conventional device, when the compressor is continuously operated at a low rotational speed, the high rotational speed operation is performed, but in this embodiment, the minimum operating frequency Hzmin is set based on the outside air temperature at the start, Control is performed so as to be at least the minimum operation frequency Hzmin throughout the operation. For this reason, when the liquid back collected in the evaporator 3 occurs in the initial stage of operation and the amount of refrigeration oil outflow increases, and when the load decreases during operation and the compressor frequency decreases, the refrigerant can return oil. A flow rate can be secured. That is, the refrigeration oil is prevented from staying in the refrigeration cycle throughout the operation, and the oil can be reliably returned to the compressor 1.
[0041]
In the control as shown in FIG. 2, when the compressor operating frequency Hz calculated so that the room temperature Tain approaches the set room temperature Tainset is equal to or higher than the minimum frequency Hzmin at which the minimum refrigerant flow rate Gmin is obtained, the frequency Hz Do not change. As described above, since the frequency Hz is not increased unnecessarily, an efficient operation can be performed without excessive capacity or excessive power consumption.
[0042]
In addition, the refrigerant flow rate is set so that a predetermined oil return time is obtained based on data (FIG. 3) obtained in advance by a test or the like for a plurality of outside air temperatures. Thereby, since the refrigeration oil discharged from the compressor 1 surely returns to the compressor 1 after a predetermined time, a more reliable refrigeration cycle apparatus can be obtained.
[0043]
When calculating the minimum refrigerant flow rate Gmin and the minimum operation frequency Hzmin in ST5 and ST6, for example, experimental data or experience data is given in a table to the storage unit of the control device 11 in advance, and this is referred to. If processing is performed in this manner, the processing is simple at the time of the heating operation start command, and can be calculated in a short time. In addition, you may calculate with an arithmetic expression instead of memorize | storing data with a table.
In ST5 and ST6, the minimum refrigerant flow rate Gmin is first set for the outside air temperature Tao, and then the minimum operation frequency Hzmin is set. However, a table may be created so that Hzmin = f (Tao).
[0044]
In addition, for example, when the table is given as the data of the minimum operating frequency Hzmin of the compressor that satisfies the oil return at that temperature with respect to the outside air temperature Tao, the number of data may be any number, but at least the outside air temperature Tao is 3 or more. On the other hand, it is preferable to set the minimum operating frequency Hzmin. In this embodiment, for example, 60 (kg / h) when the outside air temperature is lower than 0 ° C., 45 (kg / h) when 0 ° C. to 7 ° C., and 35 (kg / h) when 7 ° C. or higher. ), The minimum operating frequency Hzmin is set in three temperature ranges. It is preferable to set the minimum operating frequency appropriate for the outside air temperature, but if the minimum operating frequency is set for at least three or more outside air temperatures, the capacity becomes excessive or the power consumption is more than necessary. Some increase can be prevented. For example, when performing heating operation of an air conditioner or the like, it is necessary to determine the minimum frequency Hzmin of the compressor so as to satisfy oil return for a wide range of outside air temperature of −15 ° C. to 40 ° C. If this is to be controlled at the lowest operating frequency in two stages, the operation is performed at the minimum operating frequency Hzmin of the compressor in a temperature range at a lower temperature range in a certain temperature range. In operation when the outside air temperature is close to the higher temperature range, the capacity may become excessive to some extent, and comfort may be deteriorated or power consumption may increase. For this reason, it is desirable to set the temperature range as small as possible, but it is preferable to set the temperature range in at least three stages. At this time, the temperature range may be set in consideration of the difference in refrigerant flow rate during the required oil return time in FIG. If less than three stages of data are given, the minimum frequency of the compressor is calculated so as to satisfy the oil return by estimating between the data, and the control is performed in a multi-stage temperature range that is greater than the number of data in the storage unit 11b. You may make it carry out.
[0045]
Moreover, since the refrigeration cycle apparatus in this embodiment has the receiver 7, even if the required refrigerant amount differs depending on the installation location, it is sufficient to fill the maximum required refrigerant amount in advance. Excess refrigerant generated according to the installation location is operated in a state where it is stored in the receiver 7. For this reason, the procedure at the installation site can be simplified.
[0046]
FIG. 5 is a block diagram showing another configuration example of the refrigeration cycle of the air conditioner, for example, as the refrigeration cycle apparatus according to Embodiment 1 of the present invention. FIG. 6 shows a control flowchart of the first diaphragm device in this embodiment.
In FIG. 5, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. The operations of the refrigerant and the weakly soluble oil at the initial stage of the heating operation start command are the same as those described with reference to FIG.
[0047]
In FIG. 5, the temperature sensor 53 is provided in the discharge part of the compressor 1, and detects the temperature in the vicinity of the discharge part, that is, the discharge temperature. The configuration of the control device 12 serving as the control means is the same as that of the control device 11 shown in FIG. 4, but the control device 12 has a drive circuit for controlling the opening degree of the first expansion device 4a. The control device 12 is, for example, an outside air temperature sensor 51, a discharge temperature sensor 53, a microcomputer having a temperature input unit from the condensation temperature sensor 54, a storage unit, and an arithmetic processing unit, and a drive circuit for the first expansion device 4a. Based on the temperature detected by the sensors 51, 53, 54, the opening degree of the first expansion device 4a is controlled.
[0048]
Hereinafter, an example of the control of the opening degree of the first expansion device 4a according to this embodiment will be described based on the control flowchart shown in FIG. When the compressor 1 performs the start-up operation by the heating operation start command, the first throttling means 4a as the first throttling means is set to a predetermined start opening. When the compressor 1 performs steady operation, the opening degree of the first expansion device 4a is controlled so that the refrigerant state on the discharge side of the compressor 1 becomes the target state. For example, the opening degree of the first expansion device 4a is increased or decreased so that the discharge temperature, which is the temperature near the discharge portion of the compressor 1, converges toward a preset target discharge temperature. The control flowchart shown in FIG. 6 relates to the operation of the convergence control operation of the first expansion device 4a.
[0049]
When the convergence control operation of the first expansion device 4a is started (ST12), the control device 12 detects the outside air temperature Tao by the outside air temperature sensor 51 (ST13). Then, a first throttle device minimum opening P1min set in advance corresponding to the outside air temperature Tao is set (ST13). For example, the stable opening degree of the first throttle device 4a that converges to the target discharge temperature at each of the outside air temperatures corresponding to a plurality of outside air temperatures in advance in the storage unit of the control device 12, for example, is set as the first throttle device minimum opening degree P1min. Remember it at the table. In ST13, the first throttle device minimum opening P1min is determined for the outside air temperature Tao detected by the outside air temperature sensor 51.
[0050]
Next, in ST14 to ST20, convergence control is performed so that the discharge temperature Td during operation approaches the target discharge temperature Tdp. That is, the discharge temperature Td is detected by the discharge temperature sensor 53 (ST14), and a temperature difference ΔTd between the discharge temperature Td and the target discharge temperature Tdp is calculated (ST15). The opening degree change amount ΔP1 of the first expansion device 4a is calculated so that the temperature difference ΔTd becomes zero (ST16), and the current opening amount of the first expansion device 4a is changed by the opening amount change amount ΔP1 to The first throttle opening P1 is determined (ST17). Here, it is determined whether or not the determined first throttle opening P1 is smaller than the first throttle minimum P1min (ST18), and if it is smaller, the first throttle opening P1 is set to the first throttle minimum. The opening degree P1min is determined again (ST19). Then, the opening of the first expansion device 4a is changed to the first expansion device opening P1 determined in ST17 and ST19 (ST20).
[0051]
Thus, according to this embodiment, the first throttle device opening P1 that converges to the target discharge temperature Tdp in advance according to the outside air temperature Tao is prevented from becoming smaller than the first throttle device minimum opening P1min. is doing. The change of the opening degree P1 of the first expansion device 4a is determined based on the measured discharge temperature Td. For example, if a transient temperature sensing delay occurs, the first expansion device 4a is unnecessarily increased. There is a possibility that the opening degree P1 of the first expansion device 4a is changed so as to narrow down. By providing the minimum opening P1min, it is possible to prevent the first throttling device 4a from being narrowed more than necessary, and to prevent a transient decrease in suction pressure, a decrease in refrigerant circulation rate, a decrease in evaporation temperature, and the like. it can. Therefore, it is possible to ensure a sufficient oil movement speed and prevent the weakly mutual-soluble oil that has flowed out of the compressor 1 into the refrigerant circuit from returning to the compressor suction portion and reducing the amount of oil in the compressor for a long time. In addition, seizure due to poor lubrication of the compressor sliding portion and abnormal wear can be prevented to improve reliability.
[0052]
Note that the refrigeration cycle apparatus in this embodiment may include either one of the control processes shown in FIGS. 2 and 6 or both control processes.
Further, the outside air temperature sensor 51 detects the outside air temperature and performs control based on the outside air temperature. Instead, a temperature sensor for detecting the temperature in the container in which the evaporator 3 is stored and the temperature of the refrigerant pipe in the middle of the evaporator 3 is provided, and the evaporation temperature is detected and control is performed based on the evaporation temperature. May be. The control to increase the refrigerant flow rate when the evaporation temperature is low is the same as the case of using the outside air temperature.
In addition, in the control shown in FIG. 6, the opening degree of the first throttle device 4a is controlled so that the discharge temperature becomes the target temperature, but the refrigerant state is changed to the target state by the compressor discharge superheat instead of the discharge temperature. You may control so that it may approach. This compressor discharge superheat can be calculated from the discharge temperature of the compressor 1 detected by the discharge temperature sensor 53 and the condensation temperature of the condenser 5 detected by the condensation temperature sensor 54.
[0053]
Embodiment 2. FIG.
FIG. 7 is a block diagram showing, for example, a refrigeration cycle of an air conditioner as a refrigeration cycle apparatus according to Embodiment 2 of the present invention. The refrigeration cycle in FIG. 7 shows a state during heating operation, and FIG. 8 is a control flowchart of the first expansion device 4a according to this embodiment. In FIG. 7, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and the description thereof is omitted here.
[0054]
In FIG. 7, the configuration of the control device 13 which is a control means is the same as that of the control device 11 shown in FIG. 4, but the control device 13 has a drive circuit for controlling the opening degree of the first expansion device 4 a. Yes. The control device 13 includes, for example, a microcomputer having a temperature input unit that inputs the temperature detected by the outside air temperature sensor 51, the condensation temperature sensor 54, and the compressor shell temperature sensor 55, a storage unit, and an arithmetic processing unit, and the first expansion device 4a. And the opening degree of the first expansion device 4a is controlled based on the outside air temperature detected by the outside air temperature sensor 51. Further, the condensation temperature can be detected by the condensation temperature sensor 54 provided in the pipe of the condenser 5, and the discharge temperature of the compressor 1 can be detected by the discharge temperature sensor 53 provided in the discharge part of the compressor 1. The detected condensation temperature and discharge temperature are input to the input unit of the control device 13.
[0055]
Hereinafter, an example of the control of the opening degree of the first throttle device 4a that is the first throttle means according to this embodiment will be described based on the control flowchart of FIG. When operating the refrigeration cycle, the first throttling device 4a, which is the first throttling means, performs two types of control operations: a first throttling device start-up operation and a first throttling device convergence control operation. That is, the first throttle device start-up operation is an operation in which a predetermined start opening is set for a predetermined time after the start of heating, for example, for several minutes. The steady opening in the next convergence control operation is referred to as a steady opening, and the starting opening in the starting operation is set larger than the steady opening. Further, in the first throttle device convergence control operation, for example, as shown in FIG. 6, the compressor discharge temperature detected by the discharge temperature sensor 53 after the first throttle device start-up operation is finished approaches a preset target value. This is a control operation in which the opening degree is adjusted from the steady opening degree. The control flowchart shown in FIG. 8 relates to the activation opening set in the first expansion device 4a in the first expansion device activation operation.
[0056]
In the first throttle device start-up operation, after receiving the heating operation start command (ST21), the control device 13 detects the outside air temperature Tao by the outside air temperature sensor 51 (ST22). Then, the outside air temperature Tao is compared with a preset first reference value (ST23). If the outside air temperature Tao falls below the first reference value, the opening degree P of the first expansion device 4a is set to the first opening. Degree P1 is set (ST24). On the other hand, when the outside air temperature Tao is equal to or higher than the first reference value set in advance, the starting opening degree P of the first expansion device 4a is set as the second setting opening degree P2 (ST25). After the opening degree of the first expansion device 4a is set in ST24 and ST25, the starting operation of the first expansion device 4a is started (ST26). In the first throttle device start-up operation, the opening degree P of the first throttle device 4a set at ST24 and ST25 is the same as the opening degree P of the first throttle device 4a for a predetermined time, for example, about several minutes. As the compressor frequency is increased, the opening degree P of the first expansion device 4a is gradually increased. In any case, it is set larger than the steady opening of the first throttle device 4a in the first throttle device convergence control operation. A few minutes after starting the first throttle means starting operation in ST26, for example, as shown in FIG. 6, the first throttle device convergence control operation for increasing or decreasing the opening according to the discharge temperature is performed.
[0057]
The first set opening degree P1 of the first expansion device 4a set in ST24 is set larger than the second set opening degree P2 of the first expansion device 4a set in ST25. FIG. 9 is a graph showing the refrigerant flow rate necessary for returning oil in a predetermined oil return time that is set in advance, for example, about 10 minutes with respect to the outside air temperature. The axis indicates the refrigerant flow rate (kg / h). As the outside air temperature decreases, the oil dynamic viscosity of the weakly soluble oil increases, and it is necessary to increase the refrigerant flow rate. According to this embodiment, when the outside air temperature Tao falls below a preset first reference value, the starting opening degree of the first expansion device 4a is set large, so that a large refrigerant flow rate when the outside air temperature is low. Is obtained. For example, when the first reference value to be compared in ST23 is 0 ° C. and the outside air temperature is lower than 0 ° C., the opening is set so that a refrigerant flow rate of about 60 kg / h is obtained, Sometimes, the opening degree may be set so that a refrigerant flow rate of about 43 kg / h can be obtained.
[0058]
By setting the opening degree P of the first expansion device 4a to return to the outside air temperature Tao in a predetermined time in this way, it is possible to secure the minimum refrigerant flow rate that circulates the refrigeration cycle at the time of startup. The minimum refrigerant flow rate is a minimum value of the refrigerant flow rate at which the refrigeration oil flowing out from the compressor 1 is returned to the compressor 1 in a predetermined time, for example, about 10 minutes. By securing the flow rate of the refrigerant circulating in the refrigeration cycle in this way, the weakly soluble oil that has flowed out of the compressor 1 into the refrigerant circuit is not returned to the compressor suction portion, and the amount of oil in the compressor is reduced for a long time. The amount of the refrigerating machine oil in the compressor 1 can be maintained above the necessary minimum oil amount, seizure due to poor lubrication of the compressor sliding portion, abnormal wear, etc. can be prevented, and the reliability can be improved.
[0059]
Moreover, although the process when the first reference value is 0 ° C. has been described, the present invention is not limited to this. The first reference value is preferably set so that the refrigerant flow widths are uniform. For example, when there is a relationship as shown in FIG. 9, setting a temperature of about −4 ° C. at which the refrigerant flow rate becomes uniform can reduce the capacity from becoming excessive to some extent depending on the outside air temperature. And an increase in power consumption can be reduced.
[0060]
In the control process shown in FIG. 8, the starting opening is set to one of the two opening points P1 and P2. However, the present invention is not limited to this. Any one may be set. It is preferable to increase the data of the starting opening degree with respect to the outside air temperature because it is possible to further reduce the excessive capacity and reduce the deterioration of comfort and the increase of power consumption.
[0061]
Another configuration example according to the second embodiment of the present invention will be described. FIG. 10 is a control flowchart according to this embodiment. The configuration of the refrigeration cycle apparatus is the same as in FIG.
Hereinafter, an example of the control according to this embodiment will be described based on the control flowchart of FIG. The control process described here mainly relates to a start-up operation performed until a preset time after the start-up. In particular, when a heating operation command is issued in the air conditioner, the transition time from the start of the first throttle device starting operation that sets the opening larger than the steady opening to the transition to the first throttle device convergence control operation ts, that is, the aperture start time is controlled.
[0062]
In the first throttle device starting operation, after receiving the heating operation starting command (ST31), the control device 13 detects the outside air temperature Tao by the outside air temperature sensor 51 (ST32). Then, the outside air temperature Tao is compared with a preset second reference value (ST33), and if it falls below the second reference value, the transition time ts to the first throttle device convergence control operation is set to the first time. The set time α is set (ST34). On the other hand, when the outside air temperature Tao exceeds the preset second reference value, the transition time ts to the first throttle device convergence control operation is set as the second set time β (ST35). After setting the transition time ts to the first throttle device convergence control operation in ST34 and ST35, the first throttle device 4a is started (starting step) (ST36).
[0063]
The starting opening degree of the first throttle device 4a in ST36 is set to an opening degree larger than the steady opening degree of the first throttle device 4a in the convergence control operation, for example. The first throttle device start-up operation (ST36) is performed during the transition time ts set to about several minutes in ST37, and after the transition time ts has elapsed, the first throttle device convergence control operation (convergence step) is started (ST38). ).
[0064]
The first setting time α set in ST34 is set longer than the second setting time β set in ST35. FIG. 11 is a graph showing the oil return time when a certain refrigerant flow rate is set with respect to the outside air temperature. The abscissa indicates the outside air temperature (° C.), and the ordinate indicates the refrigerant flow rate (kg / h). The lower the outside air temperature, the higher the kinematic viscosity of the weakly soluble oil and the longer the oil return time. According to this embodiment, when the outside air temperature Tao falls below a preset second reference value, the transition time ts from the start operation of the first expansion device 4a to the convergence control operation is set to be long and the convergence control is performed. Delay driving. For this reason, it becomes possible to shift to the convergence control operation of the first expansion device 4a in a state where the weakly soluble oil that has flowed out of the compressor 1 into the refrigerant circuit at the start of heating is sufficiently returned to the compressor 1. . For example, when the second reference value to be compared in ST33 is 0 ° C. and the outside air temperature is lower than 0 ° C., a transition time ts of about 650 sec is set, and when it is 0 ° C. or more, a transition time ts of about 450 sec is set. Should be set.
[0065]
By controlling the operation time of the start operation so that the start operation for increasing the opening degree of the expansion device 4a is performed only for the time corresponding to the outside air temperature Tao, the outside air temperature is lower than when the outside air temperature is high. The convergence control operation is delayed (convergence time control step). For this reason, even when the outside air temperature is low and the kinematic viscosity of the refrigerating machine oil is large, most of the refrigerating machine oil is returned at the start of the throttle device convergence control operation, that is, the amount of oil that does not hinder the operation of the compressor 1, that is, the compression Refrigerating machine oil exceeding the required minimum oil amount of the machine 1 stays in the compressor 1. When the convergence control of the expansion device 4a is started in this state, the compressor discharge superheat is applied after a while, the refrigerant is discharged from the compressor 1 as a gas refrigerant, and there is almost no amount of liquid refrigerant in the compressor 1. Also, if the transition time ts is sufficiently long, the compressor shell temperature has increased at the time of transition to the convergence control operation of the first expansion device 4a, and in the state where the compressor shell temperature has increased, the liquid in the shell has increased. Since most of the refrigerant evaporates and is discharged, there is almost no amount of liquid refrigerant in the compressor 1. Therefore, the refrigerating machine oil in the compressor 1 is not pushed up to the upper part of the liquid refrigerant and flows out to the refrigerating cycle as at the start of operation, and a sufficient compressor oil amount can be ensured. For this reason, seizure due to poor lubrication of the compressor sliding portion, abnormal wear and the like can be prevented, and reliability can be improved.
[0066]
Here, the state in which the compressor discharge superheat is generated is a state in which the refrigerant discharged from the compressor 1 becomes superheated gas, and the discharge temperature detected by the discharge temperature sensor 53 and the condenser 5 are installed. The compressor discharge superheat calculated by the difference from the condensation temperature detected by the condensation temperature sensor 54 is a positive value. As described above, when the compressor discharge superheat is applied, the refrigerating machine oil hardly flows out from the compressor 1 to the refrigerating cycle. Further, since the liquid refrigerant does not stay in the compressor 1, control is performed so that the compressor discharge superheat is generated after the minimum required amount of refrigeration oil of the compressor 1 is retained in the compressor 1.
[0067]
Moreover, although the process when the second reference value is 0 ° C. has been described, the present invention is not limited to this. It is preferable to set the second reference value so that the width of the oil return time is uniform. For example, when there is a relationship as shown in FIG. 11, setting a temperature of about −5 ° C. that equalizes the oil return time can reduce the capacity from becoming excessive to some extent due to the outside air temperature, thereby deteriorating comfort. And an increase in power consumption can be reduced.
[0068]
Further, in the processing step of FIG. 10, the transition time is set to one of the two times α and β. However, the present invention is not limited to this, and any of the two or more transition times may be set according to the outside air temperature. It is sufficient to set it.
Further, the opening degree of the first expansion device 4a in ST36 of FIG. 10 may be set to a predetermined opening degree, or as shown in FIG. 8, it is set to have different opening degrees according to the outside air temperature. Also good.
[0069]
Furthermore, still another configuration example according to Embodiment 2 of the present invention will be described. FIG. 12 is a control flowchart of the first diaphragm device 4a according to this embodiment. The configuration of the refrigeration cycle apparatus is the same as in FIG.
The control process described here mainly includes a first throttle that adjusts the opening degree by increasing / decreasing the opening degree from the steady opening degree so that the discharge temperature and the like converge to a preset target value after completion of the first throttle device start-up operation. This relates to the apparatus convergence control operation. In particular, the first expansion device opening change amount ΔP is controlled in the first expansion device convergence control operation (convergence step) when performing the heating operation with the air conditioner.
[0070]
In the first throttle means convergence control operation, when the control device 13 starts the first throttle convergence control operation (ST41), the outside air temperature sensor 51 detects the outside air temperature Tao (ST42). Then, the outside air temperature Tao is compared with a preset third reference value (ST43), and if the outside air temperature Tao falls below the third reference value, the maximum opening change amount ΔPmax of the first expansion device 4a is set to the first value. The maximum change amount P3 is set (ST44). On the other hand, when the outside air temperature Tao is equal to or higher than a preset third reference value, the maximum opening change amount ΔPmax of the first expansion device 4a is set as the second maximum change amount P4 (ST45). In ST44 and ST45, the maximum opening change amount ΔPmax of the first expansion device 4a is set to the maximum opening change amount corresponding to the outside air temperature.
[0071]
Thereafter, the discharge temperature sensor 53 detects the discharge temperature Td (ST46), and calculates the difference ΔTd between the discharge temperature Td and the target discharge temperature Tdp (ST47). For this discharge temperature difference ΔTd, the first throttle device opening change amount ΔP is calculated so as to approach the target discharge temperature Tdp (ST48). The first opening device change amount ΔP calculated here is compared with the previously set maximum opening change amount ΔPmax of the first opening device (ST49), and the opening change amount ΔP is the maximum opening change amount ΔPmax. Is greater than the first aperture opening change amount ΔP, the maximum opening change amount ΔPmax is set (ST50). In ST51, the opening degree of the first expansion device 4a is changed according to the set opening degree ΔP. Thereafter, by repeating ST46 to ST51, the first throttle means 4a converges to the opening degree at which the target discharge temperature is obtained.
[0072]
When the outside air temperature Tao falls below a third reference value, which is a preset temperature, by the control process shown in FIG. 12, the maximum opening change amount ΔP is set small. That is, when setting the maximum opening change amount ΔPmax of the first expansion device 4a in ST44 and ST45, the first maximum change amount P3 of the first expansion device 4a is set smaller than the second maximum change amount P4. That is, the convergence time is controlled by controlling the opening / closing increase / decrease width of the first expansion device 4a (convergence time control step). For this reason, when the outside air temperature is low, it takes a long time from the start of the convergence control operation to the discharge temperature. Therefore, when the compressor discharge superheat is generated or when the compressor shell temperature rises, the weakly soluble oil that has flowed out of the compressor 1 into the refrigerant circuit at the time of start-up is sufficiently returned to the compressor 1. . As with the case where the transition time shown in FIG. 10 is set to be long, even if the compressor discharge superheat is applied or the compressor shell temperature rises and the liquid refrigerant in the compressor 1 is almost evaporated, a sufficient amount of compressor oil is obtained. Can be secured. For this reason, seizure due to poor lubrication of the compressor sliding portion, abnormal wear and the like can be prevented, and reliability can be improved.
[0073]
For example, when the third reference value to be compared in ST43 is set to 0 ° C., P4 is set to a maximum opening change amount that reaches the discharge temperature in about 450 seconds, and the outside air temperature becomes lower than 0 ° C., When P3 is set to about 0.7 times P4, the discharge temperature is reached in about 650 sec when operating at the maximum opening change amount of P3.
Moreover, although the process when the third reference value is 0 ° C. has been described, the present invention is not limited to this. It is preferable to set the third reference value so that the width of the oil return time is uniform. For example, when there is a relationship as shown in FIG. 11, setting a temperature of about −5 ° C. that equalizes the oil return time can reduce the capacity from becoming excessive to some extent due to the outside air temperature, thereby deteriorating comfort. And an increase in power consumption can be reduced.
[0074]
In the processing step of FIG. 12, the maximum opening change amount ΔP of the first expansion device 4a is set to either P3 or P4. However, the present invention is not limited to this, and two or more depending on the outside air temperature. It may be set to any one of the maximum opening change amount ΔP.
[0075]
Furthermore, still another configuration example according to Embodiment 2 of the present invention will be described. FIG. 13 is a control flowchart according to this embodiment. The configuration of the refrigeration cycle apparatus is the same as in FIG.
Hereinafter, an example of the control according to this embodiment will be described based on the control flowchart of FIG. The control process described here relates to a start-up operation that is performed until a preset time after the start, similar to the process shown in FIG. In particular, when a heating operation command is issued in the air conditioner, after the heating operation is started, the transition time from the setting of the opening degree to the first throttle device starting operation to the transition to the first throttle device convergence control operation is set. ts, that is, the aperture start time is controlled.
[0076]
In the first throttle device activation control, the control device 13 receives the heating operation activation command (ST61), and then detects the compressor shell temperature Tshell by the compressor shell temperature sensor 55 (ST62). Then, the compressor shell temperature Tshell is compared with a preset fourth reference value (ST63). If the compressor shell temperature Tshell is lower than the fourth reference value, the transition time ts to the first throttle device convergence control operation is set. The third set time γ is set (ST64). On the other hand, when the compressor shell temperature Tshell is equal to or higher than the preset fourth reference value, the transition time ts to the first expansion device convergence control operation is set as the fourth set time φ (ST65). After the transition time ts to the first throttle device convergence control operation is set corresponding to the compressor shell temperature in ST64 and ST65, the start control (start step) of the first throttle device 4a is performed (ST66).
[0077]
For example, the starting opening degree of the first expansion device 4a in ST66 is set to a predetermined value larger than the steady opening degree of the first expansion device 4a in the convergence control operation. During the transition time ts set in ST67, the first throttle device start-up operation (ST66) is performed, and after the transition time ts has elapsed, the first throttle device convergence control operation (convergence step) is started (ST68).
[0078]
Here, the third set time γ set in ST64 is set longer than the fourth set time φ set in ST65. That is, when the compressor shell temperature Tshell is lower than the preset fourth reference value, the transition time ts from the start operation of the first expansion device 4a to the convergence control operation is set to be long. Conversely, when the compressor shell temperature Tshell is equal to or higher than a preset fourth reference value, the transition time to the convergence control operation of the first expansion device 4a is shortened. For this reason, for example, in the case of initial startup when the compressor shell temperature Tshell is low, the transition time to the first throttle device convergence control operation is lengthened, and the weakly soluble oil that has flowed out of the compressor circuit 1 from the compressor 1 at the time of heating startup is compressed. The compressor shell temperature will be raised while the oil has been sufficiently returned to the machine. For example, when the fourth reference value compared in ST63 is about 30 ° C. and the compressor shell temperature is lower than 30 ° C., a transition time ts of about 650 sec is set, and when it is 30 ° C. or higher, a transition time of about 300 sec. What is necessary is just to set ts.
[0079]
In this way, the start-up operation for increasing the opening degree of the expansion device 4a is performed for a time corresponding to the compressor shell temperature Tshell to control the convergence time (convergence time control step), so that the convergence control operation of the first expansion device 4a is performed. At the time of starting, the compressor discharge superheat is applied while the weakly soluble oil that has flowed out of the compressor 1 to the refrigerant circuit is sufficiently returned to the compressor 1, and the compressor shell temperature rises. In this state, most of the liquid refrigerant is evaporated and discharged in the compressor 1, so there is almost no amount of liquid refrigerant in the compressor 1, and the refrigerating machine oil in the compressor 1 is the liquid refrigerant as at the start of operation. It is reduced that it is pushed upward and flows out into the refrigeration cycle, and a sufficient amount of compressor oil can be secured. Therefore, seizure due to poor lubrication of the compressor sliding portion, abnormal wear, etc. can be prevented, and reliability can be improved.
[0080]
Thus, in the control process shown in FIG. 13, when the compressor shell temperature is low, after securing a sufficient amount of refrigeration oil in the compressor 1, seizure due to poor lubrication of the compressor sliding portion, abnormal wear Thus, it is possible to prevent reliability problems. On the other hand, when the compressor shell temperature is high, as in the case of the thermo on / off operation, even if the liquid refrigerant is sucked at the start-up, the liquid refrigerant does not accumulate in the compressor shell and a large amount of oil discharge does not occur. By shortening the transition time to the convergence control of the first expansion device 4a, it becomes possible to quickly converge the discharge temperature to the target temperature, and to improve the start-up performance.
[0081]
Moreover, although the process when the fourth reference value is 30 ° C. has been described, the present invention is not limited to this.
Further, in the processing step of FIG. 13, the transition time is set to one of the two times γ and φ, but is not limited to this, and two or more transition times are set according to the compressor shell temperature. It may be set to either of these. Further, the starting opening degree of the first expansion device 4a in ST66 in FIG. 13 may be set to a predetermined opening degree, or set to a different opening degree according to the ambient temperature of the evaporator 3 as shown in FIG. May be.
[0082]
Here, in ST22 and ST23 in FIG. 8, ST32 and ST33 in FIG. 10, and ST42 and ST43 in FIG. 12, the outside air temperature is detected, and the start opening, transition time, and opening change amount are set with respect to the outside air temperature. However, it is not limited to the outside temperature. What is necessary is just to detect the temperature of the air around an evaporator with an evaporator ambient temperature sensor, and to set each value with respect to this temperature. For example, in the case of a cooling operation or a refrigerator of an air conditioner, the temperature of the air in the cooling space or the cooling container is obtained. Moreover, you may use evaporation temperature instead of these temperatures. The evaporation temperature can detect the temperature of the refrigerant piping of the evaporator with a temperature sensor. When the evaporation temperature is low, control is performed so that the refrigerant flow rate increases, or the transition time is lengthened or the maximum opening change amount is decreased to delay the convergence control operation, as in the case of using the outside air temperature. .
[0083]
Embodiment 3 FIG.
FIG. 14 is a block diagram showing, for example, a refrigeration cycle of an air conditioner as a refrigeration cycle apparatus according to Embodiment 3 of the present invention. Note that the refrigeration cycle of FIG. 14 shows a state during heating operation, and FIG. 15 shows a control flowchart of the first expansion device 4a and the second expansion device 4b according to this embodiment. In FIG. 14, the same reference numerals as those shown in FIG. 1 denote the same or corresponding parts, and the description thereof is omitted here. In FIG. 14, the control device 14 which is a control means has a drive circuit for controlling the opening degree of the first and second expansion devices 4 a and 4 b.
[0084]
In this embodiment, a heating operation in which the condenser 5 is installed indoors and the evaporator 3 is installed outdoors and the room is heated will be described. The second throttle device 4b, which is an upstream throttle means, is arranged in the refrigerant pipe between the condenser 5 and the receiver 7, which is a refrigerant storage means, and the first throttle device 4a, which is a downstream throttle means, is the receiver 7 and the evaporator 3. Between refrigerant pipes. The control device 11 controls the opening degree of the first expansion device 4a and the opening degree of the second expansion device 4b. The operations of other devices are the same as those in the first embodiment.
[0085]
The first throttle device 4a has two types of control operations, a first throttle device start-up operation and a first throttle device convergence control operation. That is, the first throttle device start-up operation is a control operation in which the start opening is set to a larger opening than the steady opening for a preset time and several minutes after the start of heating. This steady opening is a steady opening in the next convergence control operation. In the first throttle device convergence control operation, for example, after completion of the first throttle device start-up operation as shown in FIG. 6, the refrigerant state on the compressor discharge side, that is, the compressor discharge superheat is set to a preset target value. In this control operation, the opening degree is increased or decreased from the steady opening degree so as to converge. The compressor discharge superheat at this time can be calculated from the discharge temperature and the condensation temperature detected by the temperature sensors 53 and 54, for example.
Similar to the first throttle device 4a, the second throttle device 4b has two types of control operations, that is, a second throttle device start-up operation and a second throttle device convergence control operation. That is, the second throttle device start-up operation is a control operation in which the start opening is set to a larger opening than the steady opening for a preset time and several minutes after the start of heating. This steady opening is a steady opening in the next convergence control operation. In the second throttle device convergence control operation, after the second throttle device start-up operation is completed, the opening degree is steady so that the outlet side refrigerant state of the condenser 5, that is, the condenser subcool, converges to a preset target value. It is a control operation that adjusts by increasing or decreasing from the opening. The condenser subcool at this time can be calculated from the condensation temperature detected by the temperature sensor 54, for example.
[0086]
Here, an example of the opening control of the first diaphragm device 4a and the second diaphragm device 4b in this embodiment will be described with reference to the control flowchart of FIG. The first diaphragm device 4a is the same as that described in the second embodiment, and the second diaphragm device 4b will be mainly described here. After receiving the heating operation activation command (ST71), the control device 14 sets the opening P2 of the second expansion device 4b to the activation opening P2s (ST72), for example, for a few minutes (ST73), the second expansion device Perform start-up operation (start-up step). Here, the opening P2s is set larger than the steady opening in the second throttle device convergence control operation. After holding for a certain period of time at the start opening P2s (ST73), the opening P2 of the second expansion device 4b is reduced to the steady opening P2tei in order to shift to the second expansion device convergence control operation (convergence step). Here, the steady opening P2tei is an opening smaller than the activation opening P2s.
[0087]
In ST75, the control device 14 performs a convergence transition operation (convergence transition step). This calculates the opening change amount ΔP1 Hz of the first expansion device 4a according to the compressor operating frequency Hz at that time, and changes the opening of the first expansion device 4a from P1 to P1 + ΔP1 Hz. That is, in synchronization with the second throttle device 4b being throttled from the starting opening degree P2s to the steady opening degree P2tei, the first throttle device 4a is configured so as to alleviate the decrease in the refrigerant flow rate due to the second throttle device 4b being throttled. Increase the opening. For example, the first throttle device 4a is increased by ΔP1 Hz by the opening change amount corresponding to the compressor operating frequency. Then, after the steady opening degrees of the first and second expansion devices 4a and 4b are set in ST74 and ST75, both the first and second expansion devices are controlled to converge (ST76).
[0088]
By controlling in this way, it is possible to mitigate the transient decrease in the suction pressure of the compressor 1 when the second expansion device 4b shifts from the startup operation to the convergence control operation, and the mutual weakness due to the decrease in the refrigerant circulation amount. It is possible to prevent the return of soluble oil from deteriorating. Therefore, a sufficient amount of compressor oil can be secured to prevent seizure due to poor lubrication of the compressor sliding portion, abnormal wear, and the like, thereby improving reliability.
[0089]
For example, when the opening degree of the second expansion device 4b is about 1.5 times the steady state opening degree, when shifting from the starting operation to the convergence control operation, the opening degree of the second expansion device 4b is reduced to 2/3. However, the opening degree of the first expansion device 4a is increased in synchronization with this. The amount of increase is set according to the compressor frequency, and is opened, for example, by about half of the opening degree throttled by the second throttle device 4b. When the second throttle device 4b is throttled to about 2/3, the suction pressure of the compressor 1 decreases transiently, but by increasing the opening degree of the first throttle device 4a, the refrigerant flow rate rapidly decreases. And the suction pressure of the compressor 1 can be prevented from rapidly decreasing.
[0090]
Embodiment 4 FIG.
FIG. 16 shows a control flowchart of the first expansion device 4a of the refrigeration cycle apparatus according to Embodiment 4 of the present invention. Here, the configuration of the refrigeration cycle apparatus is the same as that of any one of Embodiments 1 to 3, and the description thereof is omitted here. This embodiment relates to the control of the opening degree of the first expansion device 4a when the heating and cooling of the air conditioner is stopped, for example, as the refrigeration cycle device. For example, the control when the heating operation is stopped is based on FIG. explain.
[0091]
When a heating operation stop command is instructed (ST81), the fans of the compressor 1 and the heat exchangers 3 and 5 are stopped (ST82). And the control apparatus 11 performs stop initial control, and sets the opening degree of the 1st expansion device 4a to the stop initial opening degree P1tei1 (ST83). This initial stop opening P1tei1 is a fully closed or very small opening. This opening is held for a predetermined time, for example, about several minutes (ST84), and after the predetermined time has elapsed, the routine proceeds to stop stationary control and the opening of the first throttle device 4a is increased so as to become the stationary stop opening P1tei2 ( ST85).
[0092]
Normally, when a heating operation stop command is instructed, the first expansion device 4a is fully opened or kept at a certain degree of opening so that the pressure difference between the high pressure side and the low pressure side becomes uniform. However, when the compressor 1 is stopped, there is a pressure difference in the refrigeration cycle, and the gas-liquid two-phase refrigerant suddenly flows from the high pressure side to the low pressure side. When the refrigeration cycle is restarted in a state where the gas-liquid two-phase refrigerant has accumulated and stopped in the low-pressure side evaporator 3, the gas-liquid two-phase refrigerant that has accumulated in the evaporator 3 suddenly flows into the compressor 1. As a result, a large amount of refrigerating machine oil is discharged from the compressor 1 to the refrigerant circuit.
[0093]
Therefore, as shown in this embodiment, the opening of the first expansion device 4a is controlled, and when the heating operation is stopped, the opening of the first expansion device 4a is first fully closed or the initial opening of the stop is a very small opening. A stop initial operation (stop initial step) is performed at a degree P1tei1 to prevent the liquid refrigerant on the high-pressure side from abruptly flowing into the evaporator 3 due to the differential pressure. Furthermore, after a predetermined time, the opening degree is opened and set to the stop steady opening degree P1tei2, and the stationary stationary operation is performed, so that the high pressure side and the low pressure side are stopped in a uniform state. After the initial stop control operation is performed, the differential pressure is reduced to some extent during the suspension for a predetermined time. Therefore, even if the opening degree of the first expansion device 4a is increased to the stop steady opening degree P1tei2, the low pressure is increased from the high pressure side. The amount of liquid refrigerant that flows into the side is smaller than when the opening degree of the first expansion device 4a is set to the stop steady opening degree P1tei2 simultaneously with the stop of the compressor 1. As a result, the amount of liquid refrigerant staying in the evaporator 3 on the low pressure side can be reduced, and the liquid back from the evaporator 3 to the suction side of the compressor 1 can be reduced when the operation is restarted. For this reason, since the quantity of the refrigerating machine oil which flows out with the liquid refrigerant from the compressor 1 at the time of starting operation can be reduced, a sufficient quantity of the refrigerating machine oil can be secured in the compressor 1 and seizure due to poor lubrication of the compressor sliding portion. Reliability can be improved by preventing abnormal wear.
[0094]
The predetermined time in ST84 is about several minutes in the above, but is not limited to this. What is necessary is just to set time until the differential pressure | voltage of a high voltage | pressure side and a low voltage | pressure side becomes small to some extent so that a liquid refrigerant may prevent flowing into the evaporator 3 rapidly by a differential pressure | voltage.
Normally, the compressor 1 is set with a prohibition time for restarting as an operating condition, and the high pressure side and the low pressure side are equalized within the range of the restart prohibition time, and the predetermined time in ST84 is made as long as possible. You only have to set it.
In addition, although control at the time of heating operation stop was described here, it is the same also at the time of cooling operation stop in the case of cooling or cooling a space using the evaporator 3.
In addition, any one or a plurality of Embodiments 1 to 3 may be combined with this embodiment.
[0095]
Embodiment 5. FIG.
FIG. 17 shows a control flowchart according to the fifth embodiment of the present invention. Here, the basic configuration of the refrigeration cycle apparatus is the same as in FIG.
The control of the opening degree of the first expansion device 4a according to this embodiment will be described with reference to FIG. The control process described here converges the discharge temperature and the like to a preset target value after completion of the first throttle device start-up operation in which the opening degree of the first throttle device 4a is set to the start opening degree and operated for a predetermined time. As described above, the first throttle device convergence control operation for adjusting the opening degree by increasing / decreasing from the steady opening degree is performed. After starting the heating operation, at the start of the first expansion device convergence control operation, it is still a transient operation after the activation, and a change occurs in the refrigeration cycle with respect to the change of the first expansion device 4a, There is also a delay in the sensing of the discharge temperature sensor 53. If the first throttling device 4a is narrowed more than necessary at this time, a transient suction pressure drop, a refrigerant circulation rate drop, a vaporization temperature drop, and the like occur. Here, the first expansion device opening change amount ΔP is controlled in the first expansion device convergence control operation when the air-conditioning apparatus performs the heating operation.
[0096]
In the first throttle means convergence control operation, when the control device 12 starts the first aperture convergence control operation (ST91), the discharge temperature sensor 53 detects the discharge temperature Td (ST92). Then, the condensation temperature Tc is detected by the condensation temperature sensor -54 (ST93), and the compressor discharge superheat SHd is calculated (ST94). The compressor discharge superheat SHd is calculated as discharge temperature Td−condensation temperature Tc (compressor discharge superheat detection step).
Since the refrigerant in the gas-liquid two-phase state is discharged from the compressor 1 when the first throttle means convergence control operation is started, the compressor discharge superheat SHd is zero. Until the compressor discharge superheat SHd> 0 for the first time in ST95, convergence control is performed in ST97 to ST99 so that the discharge temperature Td during operation approaches the target discharge temperature Tdp (convergence step). That is, a temperature difference ΔTd between the discharge temperature Td and the target discharge temperature Tdp is calculated (ST97). Then, the opening degree change amount ΔP1 of the first expansion device 4a is calculated so that the temperature difference ΔTd becomes zero (ST98), and the current opening degree of the first expansion device 4a is changed by the opening amount change amount ΔP1. The degree is changed to P1 (= P1 + ΔP1) (ST99).
[0097]
In ST97 to ST99, convergence control is performed so that the discharge temperature Td during operation approaches the target discharge temperature Tdp (convergence step), so that the opening degree of the first expansion device 4a is gradually reduced and discharged from the compressor 1. The dryness of the gas-liquid two-phase refrigerant gradually increases. That is, the compressor discharge superheat SHd = 0 for a while after the first throttle device convergence control operation is started. At a certain point in time, the compressor discharge superheat SHd> 0 and the refrigerant discharged from the compressor 1 becomes superheated gas. In the determination of ST95, the time point at which this superheated gas is discharged from the compressor 1 is detected by the value of the compressor discharge superheat SHd. When the compressor discharge superheat SHd> 0 for the first time, the opening change amount ΔP1 of the first expansion device 4a is set to ω (ω> 0) in ST96 (opening increasing step), and the current first 1 The opening degree of the expansion device 4a is changed to the opening degree P1 (= P1 + ΔP1) changed by the opening degree change amount ΔP1 (ST99).
[0098]
In ST96, ω is a positive value, for example, an opening of about 1/20 of the fully open position is set, but is not limited thereto. In the determination of ST95, when the compressor discharge superheat SHd> 0 is not satisfied for the first time, ΔP1 is set to a negative value, and the opening degree of the first expansion device 4a is controlled to be reduced. When the compressor discharge superheat SHd> 0 for the first time, ΔP1 is set to a positive value, and the opening degree of the first expansion device 4a is temporarily increased.
[0099]
Thus, according to this embodiment, it is detected for the first time that the compressor discharge superheat has been applied in the first throttle device convergence control operation, and the opening degree of the first throttle device 4a that has been reduced is temporarily detected. Increase. The change of the opening degree P1 of the first expansion device 4a is determined based on the measured discharge temperature Td. For example, if a transient temperature sensing delay occurs, the first expansion device 4a is unnecessarily increased. There is a possibility that the opening degree P1 of the first expansion device 4a is changed so as to narrow down. In particular, when the compressor discharge superheat is first detected after the compressor is started, the first expansion device 4a is already in the state of excessive expansion. At this time, by temporarily increasing the opening degree of the first expansion device 4a, it is possible to prevent the first expansion device 4a from being narrowed more than necessary, and a transient suction pressure drop, a decrease in the amount of refrigerant circulation, an evaporation temperature. Can be prevented from occurring. Therefore, it is possible to ensure a sufficient oil movement speed and prevent the weakly mutual-soluble oil that has flowed out of the compressor 1 into the refrigerant circuit from returning to the compressor suction portion and reducing the amount of oil in the compressor for a long time. In addition, seizure due to poor lubrication of the compressor sliding portion and abnormal wear can be prevented to improve reliability.
[0100]
When it is detected that the compressor discharge superheat has been applied for the first time after the start of operation in ST96, and the opening degree of the first expansion device 4a, which has been reduced until then, is temporarily increased, before the compressor discharge superheat is applied. After returning to the refrigerant state and then converging the first expansion device 4a based on the discharge temperature, it is detected that the compressor discharge superheat is generated again. At this time, since the compressor discharge superheat is not applied for the first time after the operation is started, the opening change width is set as it is in ST97 and ST98.
That is, although the compressor discharge superheat is generated once, there is a high possibility that the minimum amount of refrigerating machine oil does not stay in the compressor 1 in the first time, so the opening degree of the first throttle means 4a is changed. The amount is controlled, and operation is performed so that the compressor discharge superheat is generated after the minimum amount of refrigerating machine oil stays in the compressor 1.
[0101]
Also, in the determination of ST95, it was detected that the compressor discharge superheat was applied when the detected compressor discharge superheat became a positive value, but the compressor discharge superheat detected in consideration of measurement errors. It may be determined that the compressor discharge superheat has been applied when the temperature becomes> 1 to 3 ° C.
Further, in the control flowchart of FIG. 17, ω (ω> 0) is set to the opening change amount ΔP1 in order to temporarily increase the opening of the first expansion device 4a, but the target discharge temperature Tdp is temporarily set. The opening degree of the first expansion device 4a may be temporarily increased by lowering.
Further, the opening change amount ω may be set corresponding to the outside air temperature or the evaporation temperature. In this case, when the outside air temperature or the evaporation temperature is low, the opening degree change amount ω may be set larger than when it is high.
[0102]
Further, in the convergence control shown in FIG. 17, the opening degree of the first expansion device 4a is controlled so that the discharge temperature becomes the target temperature, but the refrigerant state is set to the target state by the compressor discharge superheat instead of the discharge temperature. You may control the opening degree of the 1st expansion device 4a so that it may approach.
The compressor discharge superheat is detected from the discharge temperature and the condensation temperature detected by the discharge temperature sensor 53 and the condensation temperature sensor 54, but may be detected by other detection means.
In addition, any one or a plurality of Embodiments 1 to 4 may be combined with this embodiment.
[0103]
In any one of the first to fifth embodiments, the refrigerant of the refrigeration cycle is an HFC refrigerant such as R32, R134a, R410A, R407C, R407E, R404A, or a natural refrigerant such as an HC refrigerant such as R290 or R600a. , R744, carbon dioxide, water, air, ammonia, etc. can provide a refrigeration cycle apparatus that can preserve the global environment without adversely affecting the global environment such as ozone layer destruction.
[0104]
The refrigerating machine oil used in the refrigeration cycle apparatus may be anything as long as it exhibits weak phase solubility in the above-mentioned refrigerant, but it is preferable to use an alkylbenzene oil having a kinematic viscosity of 8 to 32 cSt from the viewpoint of stability.
Refrigerating machine oil that is weakly soluble in the refrigerant has very high stability and is less deteriorated due to contamination with impurities. For this reason, there is a great advantage that an existing pipe can be used. For example, alkylbenzene oils that are weakly soluble in refrigerants are known as highly stable oils, and even if foreign substances such as moisture are mixed, the refrigerant circuit is blocked by the generation of sludge without being decomposed. There is little risk of losing. For this reason, at the time of installation work or the like, even if foreign matter is mixed, there is little risk of causing a failure in the system, and high reliability can be ensured.
In addition, weakly soluble oil with a kinematic viscosity of 8 to 32 cSt has sufficient fluidity in the normal operating temperature range of the air conditioner, preventing oil depletion in the compressor shell and lubricating the sliding part of the compressor. Seizure due to defects and abnormal wear can be prevented and reliability can be improved.
[0105]
When the amount of refrigerant charged in the refrigeration cycle is, for example, about three times larger than the amount of refrigeration oil, the amount of liquid refrigerant sucked into the compressor 1 at the start of heating increases and flows out of the compressor 1. The amount of refrigeration oil increases. Therefore, by applying each of the first to fifth embodiments, the effects of the present invention are further effective. If the refrigeration cycle device is prefilled with a refrigerant amount that is, for example, about three times larger than the amount of refrigeration oil, it can be used in a wide range of installation locations, and the work process according to that location during installation Can be reduced. In addition, a receiver as a liquid storage unit is not necessarily provided. However, if a receiver is provided, surplus refrigerant generated by the operation of an air conditioner having a cooling function and a heating function can be stored, so that it can be operated efficiently. .
[0106]
In each of the first to fifth embodiments, the air conditioner has been described, but each of the present invention is not limited to the air conditioner, and can be applied to a refrigeration cycle apparatus such as a refrigerator or a refrigerator. The same effect is produced.
[0107]
【The invention's effect】
  As explained above, according to the refrigeration cycle apparatus of the present invention,A refrigeration cycle using a compressor circuit, a condenser, a throttle means, and a refrigerant circuit that circulates the refrigerant by connecting the evaporator, using a refrigerating machine oil weakly soluble in the refrigerant, and the ambient temperature of the evaporator Detecting a temperature sensor, and setting a compressor minimum operation frequency corresponding to the temperature detected by the temperature sensor from a plurality of compressor minimum operation frequencies set corresponding to the ambient temperature of the evaporator, Control means for controlling the operation of the compressor at a frequency that is equal to or higher than the minimum compressor operating frequency.As a result, it is possible to prevent the amount of refrigeration oil in the compressor for a long time from decreasing, and to improve the reliability.
[0108]
  Further, according to the refrigeration cycle apparatus of the present invention, the control means can return the refrigeration oil flowing out from the compressor to the compressor within a preset time with respect to the temperature detected by the temperature sensor. Determine the lowest frequency of the compressor and place the compressor in the lowest frequency of the compressorMore thanBy controlling the frequency, it is possible to surely prevent the amount of refrigeration oil in the compressor from decreasing for a long time, and to improve the reliability.
[0109]
  According to the refrigeration cycle apparatus of the present invention, the control means returns the refrigeration oil flowing out from the compressor to the compressor within a preset time for each of a plurality of evaporator ambient temperatures. Compressor to getMinimum operationA storage unit for storing the frequency and the storage unit stored in the storage unitThe minimum operating frequency of the compressorBased on the data, the minimum compressor that can return oil to the compressor within the time with respect to the temperature detected by the temperature sensoroperationA computing unit for computing the frequency, and the compressor obtained by the computing unitoperationfrequencyMore thanBy providing the control unit that operates the compressor at a frequency, it is possible to reliably prevent the amount of refrigeration oil in the compressor from decreasing for a long time and to improve the reliability.
[0110]
Further, according to the refrigeration cycle apparatus of the present invention, it comprises a temperature sensor that detects the ambient temperature of the evaporator, and a refrigerant state detection unit that detects a refrigerant state on the compressor discharge side, and the control unit includes: The throttle means for estimating that the refrigerant state on the discharge side of the compressor detected by the refrigerant state detection means is stable in a target state with respect to the evaporator ambient temperature detected by the temperature sensor and the operating frequency of the compressor. By setting the opening to the minimum opening and controlling the throttling means at an opening larger than the minimum opening, it is possible to reliably prevent the amount of refrigeration oil in the compressor from decreasing for a long time and improve reliability. There is an effect that can be done.
[0111]
  Further, according to the refrigeration cycle apparatus of the present invention, the temperature sensor for detecting the ambient temperature of the evaporator-And the control means sets the starting opening of the throttle means to an opening that can return oil within a preset time with respect to the evaporator ambient temperature detected by the temperature sensor, and performs throttle means starting operation. By starting, it is possible to surely prevent the refrigerating machine oil in the compressor from being reduced for a long time in the start-up operation, and there is an effect of improving the reliability.
[0112]
Further, according to the refrigeration cycle apparatus of the present invention, the compressor circuit, the condenser, the throttle means, and the evaporator are connected to circulate the refrigerant, and the refrigerating machine oil weakly soluble in the refrigerant is supplied. The refrigeration cycle used, a temperature sensor for detecting the evaporator ambient temperature or the compressor shell temperature, and the necessity of the compressor in the compressor with respect to the evaporator ambient temperature or the compressor shell temperature detected by the temperature sensor Control means for controlling the amount of change in the opening of the throttle means or the throttle start timing of the throttle means so that the compressor discharge superheat is generated at the outlet of the compressor after the minimum amount of refrigeration oil is retained; With this, it is possible to prevent the amount of refrigeration oil in the compressor from decreasing and to improve the reliability.
[0113]
Further, according to the refrigeration cycle apparatus of the present invention, the refrigerant state detection means for detecting the refrigerant state on the compressor outlet side is provided, and the control means sets the throttle means to the start opening degree according to the compressor operating frequency. After the throttle means starting operation for setting and operating, and after the throttle means starting operation, the opening degree of the throttle means is increased or decreased so that the refrigerant state on the compressor discharge side detected by the refrigerant state detecting means approaches the target state. By performing the throttle means convergence control operation, and by making the time of the throttle means starting operation when the evaporator ambient temperature is low longer than the time of the throttle means starting operation when the evaporator ambient temperature is high, It is possible to reliably prevent the amount of refrigeration oil in the compressor from decreasing, and to improve the reliability.
[0114]
Further, according to the refrigeration cycle apparatus of the present invention, the refrigerant state detection means for detecting the refrigerant state on the compressor outlet side is provided, and the control means sets the throttle means to the start opening degree according to the compressor operating frequency. After the throttle means starting operation for setting and operating, and after the throttle means starting operation, the opening degree of the throttle means is increased or decreased so that the refrigerant state on the compressor discharge side detected by the refrigerant state detecting means approaches the target state. The throttle means convergence control operation is performed, and the time for the throttle means starting operation when the shell temperature is high is shorter than the time for the throttle means starting operation when the shell temperature is low. It is possible to reliably prevent the amount of machine oil from being reduced, and to efficiently operate and to improve the reliability.
[0115]
Further, according to the refrigeration cycle apparatus of the present invention, the refrigerant state detection means for detecting the refrigerant state on the compressor outlet side is provided, and the control means sets the throttle means to the start opening degree according to the compressor operating frequency. The throttle means start-up operation to be set, and the throttle means convergence to increase or decrease the opening degree of the throttle means so that the refrigerant state on the compressor discharge side detected by the refrigerant state detection means approaches the target state after the throttle means start-up operation And performing a control operation, and by setting the maximum opening change amount when the evaporator ambient temperature in the throttle means convergence control operation is low, smaller than the maximum opening change amount when the evaporator ambient temperature is high, It is possible to reliably prevent the amount of refrigeration oil in the compressor from decreasing, and to improve the reliability.
[0116]
Further, according to the refrigeration cycle apparatus of the present invention, the compressor circuit, the condenser, the throttle means, and the evaporator are connected to circulate the refrigerant, and the refrigerating machine oil weakly soluble in the refrigerant is supplied. The refrigeration cycle used, the compressor discharge superheat detection means for detecting the compressor discharge superheat on the compressor outlet side, and the compressor discharge superheat for the first time after starting operation with the compressor discharge superheat detection means And a control means for increasing the opening of the throttle means when it is detected, it is possible to reliably prevent the amount of refrigerating machine oil in the compressor from being reduced, and to improve the reliability.
[0117]
Further, according to the refrigeration cycle apparatus of the present invention, the compressor circuit has a refrigerant circuit for circulating the refrigerant by sequentially connecting the compressor, the condenser, the expansion device, and the evaporator, and the refrigerating machine oil is weakly soluble in the refrigerant. In the refrigeration cycle using the above, when the operation is stopped, the stop initial operation for setting the opening of the expansion device to the initial stop opening, and the opening of the expansion device after the initial stop operation is set to be smaller than the initial stop opening. By providing control means to perform a steady stop operation that is set to a large value, the amount of liquid back from the evaporator at the time of startup to the compressor suction side is reduced to reduce the amount of refrigerating machine oil flowing out of the compressor, and compression The amount of refrigerating machine oil in the machine can be secured and the reliability can be improved.
[0118]
Further, according to the refrigeration cycle device of the present invention, the compressor, the evaporator, the first throttle means, the liquid reservoir means, the second throttle means, and the condenser are connected in order to circulate the refrigerant, In a refrigeration cycle using refrigeration oil that is weakly soluble in the refrigerant, the second throttle means starting operation for setting the opening degree of the second throttle means to the starting opening degree of the second throttle means, and the second throttle After the means starting operation, the second throttle means is set to a steady opening smaller than the starting opening, and the convergence transition operation for increasing the opening of the first throttle means by a predetermined opening, and the convergence transition operation And a second throttle means convergence control operation for controlling the refrigerant state on the outlet side of the condenser by increasing / decreasing the opening degree of the second throttle means later, so that the second throttle means is activated. Transition from operation to steady control operation Compressor suction pressure is prevented from being lowered in, can ensure sufficient compressor oil quantity, there is an effect of improving reliability.
[0119]
In addition, according to the refrigeration cycle apparatus of the present invention, the refrigeration cycle is provided with a liquid storage means, and the amount of refrigerant more than three times the amount of refrigerating machine oil is enclosed, so that the installation process can be facilitated, and It is possible to prevent the amount of refrigerating machine oil in the compressor from decreasing, and to improve the reliability.
[0120]
Further, according to the refrigeration cycle apparatus of the present invention, the HFC refrigerant or the natural refrigerant is used as the refrigerant, thereby reducing the adverse effects on the global environment such as ozone layer destruction and maintaining the global environment.
[0121]
Further, according to the refrigeration cycle apparatus of the present invention, the refrigerating machine oil can be obtained by using an alkylbenzene-based oil having a kinematic viscosity of 8 to 32 cSt, which is highly resistant to deterioration and has sufficient fluidity in the operating temperature range. It has the effect of improving reliability.
[0122]
Further, according to the control method of the refrigeration cycle apparatus of the present invention, the starting step of gradually increasing the frequency of the compressor and setting the opening of the throttle means to the starting opening according to the frequency, and the compressor is loaded A throttle means converging step for reducing the opening degree of the throttle means to be smaller than the starting opening degree after reaching a predetermined rotational speed according to the pressure, and bringing the refrigerant state on the compressor outlet side closer to the target state; and an evaporator A convergence time control step for controlling an operating time of the start-up step or an opening / closing increase / decrease width of the throttle means in the throttle means convergence step with respect to the ambient temperature or the compressor shell temperature. This has the effect of preventing the amount of refrigerating machine oil from decreasing and improving reliability.
[0123]
According to the control method of the refrigeration cycle apparatus of the present invention, the compressor stop step for stopping the operation of the compressor, and the stop initial stage for setting the opening of the throttle means to the stop initial opening after the compressor stop step And a stationary stop step for setting the opening of the throttle means to be larger than the initial stop opening after the initial stop step, so that the liquid from the evaporator at the start to the compressor suction side is provided. There is an effect that the amount of refrigerating machine oil flowing out from the compressor can be reduced by reducing the back amount, the amount of refrigerating machine oil in the compressor can be secured, and the reliability can be improved.
[0124]
Further, according to the control method of the refrigeration cycle apparatus of the present invention, after the upstream throttle means starting step of operating the upstream side throttle means of the refrigerant storage means with the startup opening set, and after the upstream throttle means starting step, An upstream throttle means convergence step for increasing or decreasing the degree of opening of the upstream throttle means to bring the refrigerant state on the outlet side of the condenser closer to the target state, and a transition from the upstream throttle means activation step to the upstream throttle means convergence step A convergence transition step for increasing the opening degree of the downstream throttle means of the refrigerant storage means so as to alleviate the decrease in the refrigerant flow rate due to the decrease in the opening degree of the upstream throttle means. As a result, when the second throttle means shifts from the starting operation to the steady control operation, it is possible to prevent the compressor suction pressure from being lowered transiently and to secure a sufficient amount of refrigeration oil in the compressor. There is an effect that the reliability can be improved.
[0125]
Further, according to the control method of the refrigeration cycle apparatus of the present invention, the compressor discharge superheat detection step for detecting the compressor discharge superheat, and the compressor discharge superheat is attached for the first time in the compressor discharge superheat detection step. An opening increasing step for increasing the opening of the throttle means when it is detected, and a throttle means convergence step for increasing or decreasing the opening of the throttle means to bring the refrigerant state on the compressor outlet side closer to the target state. By providing, there is an effect that a sufficient amount of refrigerating machine oil can be surely secured in the compressor and reliability can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a control flowchart according to the first embodiment.
FIG. 3 is a graph showing the relationship between the refrigerant flow rate and the oil return time with respect to the outside air temperature in the first embodiment.
FIG. 4 is a block diagram illustrating a configuration of a control device according to the first embodiment.
5 is a configuration diagram showing another configuration example of the refrigeration cycle apparatus according to Embodiment 1. FIG.
FIG. 6 is a control flowchart according to another configuration example of the first embodiment.
FIG. 7 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 2 of the present invention.
FIG. 8 is a control flowchart according to the second embodiment.
FIG. 9 is a graph showing the refrigerant flow rate necessary for securing the same oil return time with respect to the outside air temperature according to the second embodiment.
10 is a control flowchart according to another configuration example of the second embodiment. FIG.
FIG. 11 is a graph showing the relationship between the outside air temperature and the oil return time with respect to the refrigerant flow rate according to the second embodiment.
FIG. 12 is a control flowchart according to still another configuration example of the second embodiment.
FIG. 13 is a control flowchart according to still another configuration example of the second embodiment.
FIG. 14 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 3 of the present invention.
FIG. 15 is a control flowchart according to the third embodiment.
FIG. 16 is a control flowchart according to the fourth embodiment of the present invention.
FIG. 17 is a control flowchart according to the fifth embodiment of the present invention.
[Explanation of symbols]
1 compressor, 2 four-way valve, 3 evaporator, 4 throttle device, 4a first throttle means (downstream throttle means), 4b second throttle means (upstream throttle means), 5 condenser, 7 liquid reservoir means, 9 Intake piping, 11, 12, 13, 14 control means, 51 outside air temperature sensor, 52 indoor temperature sensor, 53 discharge temperature sensor, 54 condensing temperature sensor, 55 compressor shell temperature sensor.

Claims (8)

圧縮機、凝縮器、絞り手段、蒸発器を接続して冷媒を循環させる冷媒回路を有し、前記冷媒に対して弱相互溶解性の冷凍機油を用いた冷凍サイクルと、前記圧縮機出口側の圧縮機吐出スーパーヒートを検知する圧縮機吐出スーパーヒート検知手段と、前記圧縮機吐出スーパーヒート検知手段で運転起動後に初めて圧縮機吐出スーパーヒートがついたことを検知した時に前記絞り手段の開度を増加させる制御手段と、を備えたことを特徴とする冷凍サイクル装置。  A refrigerant circuit for connecting a compressor, a condenser, a throttle means, and an evaporator to circulate the refrigerant; a refrigeration cycle that uses refrigeration oil that is weakly soluble in the refrigerant; Compressor discharge superheat detection means for detecting compressor discharge superheat, and opening degree of the throttle means when the compressor discharge superheat detection means detects that compressor discharge superheat has been applied for the first time after starting operation. A refrigeration cycle apparatus comprising: a control means for increasing the refrigeration cycle apparatus. 圧縮機、蒸発器、第１絞り手段、液溜め手段、第２絞り手段、凝縮器を順次接続して冷媒を循環させる冷媒回路を有し、前記冷媒に対して弱相互溶解性の冷凍機油を用いた冷凍サイクルにおいて、前記第２絞り手段の開度を第２絞り手段の起動開度に設定する第２絞り手段起動運転と、前記第２絞り手段起動運転の後に前記第２絞り手段を前記起動開度よりも小さい定常開度に設定すると共に、前記第１絞り手段の開度を所定開度大きくする収束移行運転と、前記収束移行運転の後に前記第２絞り手段の開度を増減して前記凝縮器の出口側の冷媒状態を制御する第２絞り手段収束制御運転と、を行なう制御手段を備えたこと特徴とする冷凍サイクル装置。  A compressor circuit, an evaporator, a first throttle means, a liquid reservoir means, a second throttle means, and a condenser circuit are connected in order to circulate the refrigerant. In the refrigeration cycle used, the second throttle means start-up operation for setting the opening degree of the second throttle means to the start degree of the second throttle means, and the second throttle means after the second throttle means start-up operation A convergence transition operation in which the opening degree of the first throttle means is set to a predetermined opening degree larger than the starting opening degree, and the opening degree of the second throttle means is increased or decreased after the convergence transition operation. And a second squeezing means convergence control operation for controlling the refrigerant state on the outlet side of the condenser. 冷凍サイクル内に液溜め手段を備えると共に、冷凍機油量に対して３倍以上の冷媒量を封入したことを特徴とする請求項１または請求項２に記載の冷凍サイクル装置。The refrigeration cycle apparatus according to claim 1 or 2 , wherein a liquid storage means is provided in the refrigeration cycle, and a refrigerant amount that is three times or more the amount of refrigerating machine oil is enclosed. 冷媒は、ＨＦＣ冷媒または自然冷媒を用いることを特徴とする請求項１乃至請求項３のいずれか１項に記載の冷凍サイクル装置。The refrigeration cycle apparatus according to any one of claims 1 to 3 , wherein the refrigerant is an HFC refrigerant or a natural refrigerant. 冷凍機油は、動粘度８〜３２ｃＳｔのアルキルベンゼン系油を用いることを特徴とする請求項１乃至請求項４のいずれか１項に記載の冷凍サイクル装置。The refrigeration cycle apparatus according to any one of claims 1 to 4 , wherein the refrigeration oil uses an alkylbenzene oil having a kinematic viscosity of 8 to 32 cSt. 圧縮機の周波数を徐々に上げ、前記周波数に伴って絞り手段の開度を起動開度に設定する起動ステップと、前記圧縮機が負荷に応じた所定の回転数に達した後に前記絞り手段の開度を前記起動開度よりも小さく絞って増減させ、圧縮機出口側の冷媒状態を目標状態に近づける絞り手段収束ステップと、蒸発器周辺温度または圧縮機シェル温度に対して、前記起動ステップの運転時間または前記絞り手段収束ステップの前記絞り手段の開度増減幅を制御する収束時間制御ステップと、を備えた冷凍サイクル装置の制御方法。  A starting step of gradually increasing the frequency of the compressor and setting the opening of the throttle means to the starting opening according to the frequency; and after the compressor reaches a predetermined rotational speed according to a load, A throttle means convergence step for reducing the opening degree to be smaller than the start opening degree to increase or decrease the refrigerant state on the compressor outlet side to a target state, and for the evaporator ambient temperature or the compressor shell temperature, A control method for a refrigeration cycle apparatus, comprising: a convergence time control step for controlling an operation time or an opening / closing increase / decrease width of the throttle means in the throttle means convergence step. 冷媒貯溜手段の上流側絞り手段を起動開度に設定して運転する上流側絞り手段起動ステップと、前記上流側絞り手段起動ステップの後に前記上流側絞り手段の開度を増減させて凝縮器出口側の冷媒状態を目標状態に近づける上流側絞り手段収束ステップと、前記上流側絞り手段起動ステップから前記上流側絞り手段収束ステップに移るときの前記上流側絞り手段の開度の減少による冷媒流量の減少を緩和するように前記冷媒貯溜手段の下流側絞り手段の開度を増加させる収束移行ステップと、を備えた冷凍サイクル装置の制御方法。  An upstream throttle means starting step that operates with the upstream throttle means of the refrigerant storage means set to the startup opening degree, and a condenser outlet by increasing or decreasing the opening degree of the upstream throttle means after the upstream throttle means starting step. An upstream throttle means convergence step for bringing the refrigerant state on the side closer to the target state, and a refrigerant flow rate due to a decrease in the opening degree of the upstream throttle means when the upstream throttle means starting step is shifted to the upstream throttle means convergence step. A control method for a refrigeration cycle apparatus, comprising: a convergence transition step for increasing an opening degree of a downstream throttle means of the refrigerant storage means so as to alleviate the decrease. 圧縮機吐出スーパーヒートを検知する圧縮機吐出スーパーヒート検知ステップと、前記圧縮機吐出スーパーヒート検知ステップで初めて前記圧縮機吐出スーパーヒートがついたことを検知したときに絞り手段の開度を増加させる開度増加ステップと、前記絞り手段の開度を増減させて圧縮機出口側の冷媒状態を目標状態に近づける絞り手段収束ステップと、を備えた冷凍サイクル装置の制御方法。  Compressor discharge superheat detection step for detecting compressor discharge superheat, and the opening degree of the throttle means is increased when it is detected for the first time that the compressor discharge superheat is detected in the compressor discharge superheat detection step. A control method for a refrigeration cycle apparatus, comprising: an opening degree increasing step; and a throttle means convergence step for increasing or decreasing an opening degree of the throttle means to bring the refrigerant state on the compressor outlet side closer to a target state.
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