JP4156097B2

JP4156097B2 - Air conditioner

Info

Publication number: JP4156097B2
Application number: JP27606398A
Authority: JP
Inventors: 徹久保; 泰史佐野; 芳浩伊藤; 一郎本郷
Original assignee: Toshiba Carrier Corp
Current assignee: Toshiba Carrier Corp
Priority date: 1998-09-29
Filing date: 1998-09-29
Publication date: 2008-09-24
Anticipated expiration: 2018-09-29
Also published as: JP2000104975A

Description

【０００１】
【発明の属する技術分野】
本発明は暖房運転中に除霜運転を行なう制御手段を具備したヒートポンプ型空気調和機に係り、特に、暖房運転中に、所定時間経過毎に除霜運転を開始させる除霜運転制御手段を設けた空気調和機に関する。
【０００２】
【従来の技術】
一般に、この種のヒートポンプ型空気調和機では、暖房運転中に、四方弁の切換操作により、冷凍サイクルの冷媒の循環方向を逆転させることにより、室外熱交換器を凝縮器として作用させる除霜運転を行なって、この室外熱交換器の着霜を除霜することができる。しかし、低外気温度の暖房運転時には、室外熱交換器の着霜過剰による暖房能力低下と、この暖房能力低下を補償するために上昇される圧縮機の運転周波数（単位時間当りの回転数）の上昇に伴う吐出温度の上昇による圧縮機のケースサーモ異常と、を生ずる場合がある。
【０００３】
これらの課題に対し、従来の空気調和機は次のように対応している。
【０００４】
（１）室外熱交換器の着霜過剰に対しては、図８で示す、いわゆる低下量検出方式により設定された除霜運転開始条件が充足されたときに、暖房運転中に除霜運転を開始させる制御手段を設けている。
【０００５】
この低下量検出方式は、暖房起動時、あるいは除霜運転から暖房運転へ復帰時（図８では０時間）から所定時間（例えば１０分）経過してサイクル温度が安定した後、所定時間（例えば５分間）の室外熱交温度最低値ＴＥ０検出時間において、室外熱交換器の温度（以下、室外熱交温度ＴＥという）が最も低下したときの最低値ＴＥ０を検出し、この最低値ＴＥ０に対する室外熱交温度ＴＥとその低下量（ＴＥ０−ＴＥ）に応じて、除霜運転をそれぞれ開始させる領域を、図９にも示すように例えば３つＡ，Ｂ，Ｃのゾーンにそれぞれ設定している。そして、室外熱交温度ＴＥまたはこれと熱交温度最低値ＴＥ０との差がＡ，Ｂ，Ｃゾーンのいずれかの領域にそれぞれ到達し、その到達が所定時間（例えば３分間）継続したときに、除霜運転が開始される。
【０００６】
（２）一方、吐出温度上昇に対しては、圧縮機の吐出温度を検出する吐出温度センサを設け、この吐出温度センサにより所定の吐出温度上昇を検出したときに、圧縮機の運転周波数を低下させて圧縮機のケースサーモ異常を防止するように構成している。
【０００７】
これに対し、吐出温度センサを設けない吐出温度推定方式もある。この方式は、吐出温度を、室内熱交温度センサと室外熱交温度センサとによる両検出温度と、圧縮機の運転周波数の関数とにより推定し、吐出温度上昇に対応するものである。
【０００８】
【発明が解決しようとする課題】
しかしながら、上記のように吐出温度センサを設ける従来例では、その分コストがアップするという課題がある。
【０００９】
また、上記のように吐出温度センサを設けない吐出温度推定方式では、冷媒が循環する冷媒配管が短かい短配管接続の場合に室内熱交温度センサによる検出温度が低くなり過ぎてしまう場合がある。
【００１０】
すなわち、図１０に示すように、室外熱交換器の着霜量が増えると、室外熱交換器での冷媒蒸発量が減少するので、その分、圧縮機への冷媒の液バック量が増加する。これを防止するために、電子膨張弁が絞られ、室内熱交換器への冷媒ホールド量が増加して行くので、室内熱交温度センサの位置で過冷却状態になる。このために、吐出温度を低目に推定してしまうので、コンプレッサのケースサーモによる異常停止に至ってしまうという課題がある。
【００１１】
さらに、長配管接続や冷媒量不足による室外熱交温度ＴＥの最低値ＴＥ０の低下、その最低値ＴＥ０の検出後の外気条件の変化等の場合には、これらＴＥやこれとＴＥ０との差が除霜開始領域Ａ，Ｂ，Ｃ内に入りにくくなって除霜運転が開始し難くなり、着霜過剰による暖房能力低下を招くという課題がある。
【００１２】
本発明はこのような事情を考慮してなされたもので、その目的は、吐出温度センサの有無に拘らず、圧縮機のケースサーモによる異常停止と、室外熱交換器の着霜過剰による暖房能力の低下を防止することができる空気調和機を提供することにある。
【００１３】
【課題を解決するための手段】
請求項１ないし３の発明は、暖房運転時の室外熱交換器の温度である室外熱交温度が予め定めた第１の除霜領域に到達し、暖房起動もしくは除霜復帰後所定時間における室外熱交温度の最低値と上記室外熱交温度との差である低下値が、所定値以上になったときに、除霜運転を開始させる制御手段を有する空気調和機において、上記制御手段に、上記室外熱交温度、上記室外熱交温度の最低値、または外気温度のいずれかが予め定めた第２の除霜領域内にそれぞれ到達したときに、除霜運転を、上記暖房起動時もしくは除霜復帰時から所定時間経過毎に開始させる除霜運転制御手段を設けたことを特徴とする空気調和機である。
【００１４】
この発明によれば、暖房運転中、室外熱交温度が第１の除霜領域内に到達したとき、あるいはこの室外熱交換温度とその所定時間内の最低値との差である低下値が所定値以上のときには、除霜運転がそれぞれ開始される。
【００１５】
一方、外気温度、室外熱交温度およびその最低値のいずれかが第２の除霜領域に到達したときには、暖房起動時あるいは除霜運転復帰時（以下暖房起動時等という）から所定時間経過毎に、除霜運転が開始される。すなわち、従来の低下量検出方式と並行して所定時間経過毎に除霜運転を行なう除霜開始条件を設定している。
【００１６】
したがって、室外熱交温度、その最低値、外気温度のいずれかがそれぞれの第２の所定領域に到達したときには、除霜運転が開始される。しかも、その後は、仮に長配管接続や冷媒量不足の暖房起動時に室外熱交換温度の最低値が低下し、さらに、この室外熱交温度最低値検出後に外気温度が上昇して室外熱交温度も高くなったときには、これら両温度差（ＴＥ０−ＴＥ）が縮小して低下値が所定値以下になり易くなるが、一旦、第２の除霜領域に到達すると、以後、暖房起動時等から所定時間経過毎に除霜運転を毎回開始するので、室外熱交換器の着霜過剰を未然に防止することができる。このために、着霜過剰による圧縮機の運転周波数の上昇を抑制できる。
【００１７】
したがって、一旦、第２の除霜領域内において除霜運転を開始させると、以後は、所定時間経過毎に除霜運転を開始させるので、吐出温度センサがなくてもコンプレッサのケースサーモ異常に至らず暖房運転を継続することができる。すなわち、吐出温度センサを省略できるので、その分、コストを低減させることができる。
【００１８】
請求項４の発明は、除霜運転制御手段は、外気温度に応じて、除霜運転を所定時間経過毎に開始させる当該所定時間を制御する機能を有することを特徴とする請求項１ないし請求項３のいずれかに記載の空気調和機であり、請求項５の発明は、外気温度が低くなるに従って上記所定時間を長くするものである。
【００１９】
これらの発明によれば、外気温度に応じて、除霜運転を所定時間経過毎に開始させる当該所定時間を制御するので、吐出温度センサがなくてもコンプレッサのケースサーモ異常に至らず暖房運転を継続することができる。
【００２０】
請求項６の発明は、除霜運転制御手段は、室外熱交温度に応じて、除霜運転を所定時間経過毎に開始させる当該所定時間を制御する機能を有することを特徴とする請求項１記載の空気調和機であり、請求項７の発明は、室外熱交温度が低くなるに従い、上記所定時間を長くするものである。
【００２１】
これらの発明によれば、室外熱交温度に応じて、除霜運転を所定時間経過毎に開始させる当該所定時間を制御するので、吐出温度センサがなくてもコンプレッサのケースサーモ異常に至らず暖房運転を継続することができる。
【００２２】
請求項８の発明は、除霜運転制御手段は、室外熱交温度の最低値が低くなるに従い、除霜運転を所定時間経過毎に開始させる当該所定時間を長くするよう制御する機能を有することを特徴とする請求項１ないし請求項３のいずれかに記載の空気調和機である。
【００２３】
この発明によれば、室外熱交温度の最低値に応じて、除霜運転を所定時間経過毎に開始させる当該所定時間を制御するので、吐出温度センサがなくてもコンプレッサのケースサーモ異常に至らず暖房運転を継続することができる。
【００２４】
【発明の実施の形態】
以下、本発明の実施形態を図１〜図７に基づいて説明する。
【００２５】
図２は本発明の一実施形態に係る空気調和機１の冷凍サイクル図である。この空気調和機１は、コンプレッサ２、冷媒流路切り換え機能を有する四方弁３、室内ファン４ａを有する室内熱交換器４、膨張弁としての電子制御弁（ＰＭＶ）５、および室外ファン６ａを有する室外熱交換器６を、冷媒配管７を介して順次かつ環状に連通させて冷媒を可逆的に循環させる冷凍サイクルを構成している。
【００２６】
冷媒としては、Ｒ２２よりも同一温度で飽和圧力が高い、例えば５０℃における飽和圧力が２５００ｋＰａ以上の代替冷媒を用いている。なお、このような代替冷媒として特にオゾン層を破壊しないものとしては、Ｒ３２（ＣＨ₂Ｆ₂）とＲ１２５（ＣＨＦ₂ＣＦ₃）との合成組成が８０％以上の冷媒、Ｒ１４３ａ（ＣＨ₃ＣＦ₃）との合成組成が８０％以上の冷媒、およびＲ３２（ＣＨ₂Ｆ₂）の組成が４５％以上の冷媒等がある。
【００２７】
そして、空気調和機１は、室内ファン４ａおよび室外ファン６ａの運転時における四方弁３の切換制御により、冷媒を、図中実線矢印に示すように、コンプレッサ２→四方弁３→室外熱交換器（凝縮作用）６→膨張弁（ＰＭＶ）５→室内熱交換器（蒸発作用）４→四方弁３→コンプレッサ２に循環させることにより冷房運転する一方、冷媒を図中破線矢印に示すように、コンプレッサ２→四方弁３→室内熱交換器（凝縮作用）４→膨張弁５→室外熱交換器（蒸発作用）６→四方弁３→コンプレッサ２に循環させることにより暖房運転するように構成されている。
【００２８】
さらに、暖房運転時において室内ファン４ａおよび室外ファン６ａを停止させるとともに四方弁３を切り換え制御して、冷媒を暖房時における循環方向とは逆方向（図中実線矢印方向）に循環させることにより、室外熱交換器に凝縮作用をさせて除霜運転を行なうようになっている。
【００２９】
そして、コンプレッサ２、四方弁３、ＰＭＶ５、室外熱交換器６、および室外ファン６ａは、室外に設置される室外ユニット内に設けられる。また、室外ユニットには、室外熱交換器６に設置されて、その室外熱交換器６の温度を検出する室外熱交温度センサ９と、室外熱交換器６自体に、あるいはその室外熱交換器６近傍に設けられて、外気温度を検出する外気温センサ１０とを備えている。
【００３０】
また、室内熱交換器４と室内ファン４ａとは室内に設置される室内ユニット１３に設けられる。室内ユニット１３には、室内の温度を検出する室温センサ１１と、室内熱交換器４に設置されて、その室内熱交換器４の冷媒凝縮温度を検出する室内熱交温度センサ１２とを備えている。
【００３１】
図３は上記室内ユニット１３および室外ユニット１４を具備した空気調和機１全体の制御系を示す。室外ユニット１４は、例えばマイクロコンピュータを搭載した室外制御部１５を有する。この室外制御部１５は、その制御に必要な情報データ等を記憶するメモリとしてＥＥＰＲＯＭ１５ａを備えており、この室外制御部１５には交流電源供給ラインＬａと通信線Ｌｂとを介して室内制御部１６を電源供給と双方向通信可能に接続している。
【００３２】
また、室外制御部１５には、室外熱交温度センサ９、外気温センサ１０、室外ファン６ａのファンモータ６ｂを駆動制御するファン駆動回路１７、例えば電磁弁等よりなる四方弁（４Ｖ）３、電子膨張弁（ＰＭＶ）５、コンプレッサ２のモータ２に印加する印加電圧とその運転周波数を制御することにより、このモータ２ａの単位時間当りの回転数を制御するインバータ回路１８をそれぞれ電気的に接続している。
【００３３】
一方、室内ユニット１３は、例えばマイクロコンピュータを搭載した室内制御部１６を備えている。この室内制御部１６には、電源供給用の交流電源１９および遠隔操作制御用のリモコン２０がそれぞれ接続されている。
【００３４】
また、室内制御部１８には、前述した室温センサ１１、室内熱交温度センサ１２、室内ファン４ａを回転させるファンモータ（ＦＭ）２１の回転速度を制御する速度制御回路２２、上下風向調節ルーバの揺動軸を中心に回転させて揺動させるルーバモータ（ＲＭ）２３の回転角度を制御しながら駆動させるルーバ駆動回路２４をそれぞれ電気的に接続している。
【００３５】
そして、室内制御部１６には、暖房運転中に、所定の除霜運転開始条件が充足されたときに、除霜運転を開始させる除霜運転制御手段１６ａを設けている。
【００３６】
図１はこの除霜運転制御手段１６ａにより設定された除霜運転開始条件を示す模式図であり、暖房運転中に、除霜運転を開始させる条件として、例えば５つの除霜運転開始ゾーン（除霜領域）Ａ，Ｂ，Ｃ，Ｄ，Ｅを設けている。
【００３７】
これら除霜運転開始ゾーンＡ〜Ｅは、図８，図９で示す従来の、いわゆる低下量検出方式に基づいて設定された第１の除霜領域である２領域の除霜運転開始ゾーンＣ，Ａと室外熱交温度が−２０℃以下のような極低温時に低下量に関係なく除霜運転を強制実行させる除霜運転開始ゾーンに、本発明の一実施形態として今回新たに設定された第２の除霜領域である例えば２つの除霜領域の除霜運転開始ゾーンＤ，Ｅを併行条件として追加することにより構成されている。
【００３８】
すなわち、図８，図９でも示すように除霜運転開始ゾーンＡは、暖房起動時、あるいは除霜運転から暖房運転に復帰後から所定時間、例えば１０〜１５分間のＴＥ０検出時間において、室外熱交温度センサ９により検出された室外熱交換器６の温度（以下室外熱交温度ＴＥという）の最低値ＴＲ０と、このＴＥ０検出時間後の室外熱交温度ＴＥとの差（ＴＥ０−ＴＥ）、つまり低下量が所定値、例えば２．５℃以上（ＴＥ０−ＴＥ≧２．５℃）に到達し、その状態が３分間継続したときに、除霜運転を開始させる領域である。
【００３９】
また、除霜運転開始ゾーンＢは、室外熱交温度ＴＥが所定値、例えば−２０℃以下（ＴＥ≦−２０℃）に３分間継続して到達したときに、除霜運転が開始され、除霜運転開始ゾーンＣは、室外熱交温度ＴＥとその最低値ＴＥ０の差が所定値、３．０℃以上（ＴＥ０−ＴＥ≧３．０℃）に３分間継続して到達したときに除霜運転が開始されるようになっている。
【００４０】
したがって、例えば外気温度Ｔ０が０℃で暖房起動し、起動後１０〜１５分間での室外熱交温度最低値ＴＥ０が−３℃、かつ起動から３７分経過後（３４＋３分）に室外熱交温度ＴＥが−６℃以下になった時点でＣゾーンで除霜運転が開始される。さらに、外気温度が比較的に低い−５℃で暖房起動した場合、室外熱交温度最低値ＴＥ０が−８℃で、起動から３１分（２８＋３分）経過後に室外熱交温度ＴＥが−１０．５℃以下になった時点でＡゾーンで除霜運転が開始される。
【００４１】
一方、図４〜図６に示すように、本実施形態に係る除霜運転開始ゾーンＤは、外気温度Ｔ０が例えば−１０≦Ｔ０＜−５℃を充足したとき、または室外熱交温度ＴＥが−１６≦ＴＥ＜−１１℃を充足したとき、あるいは室外熱交温度最低値ＴＥ０が−１３≦ＴＥ０＜−８℃を充足したときに、除霜運転を開始させる領域である。そして、Ｄゾーンに到達すると、除霜運転制御手段１６ａにより、暖房起動時、あるいは除霜運転から暖房運転への復帰時から所定の除霜間隔時間Ｔ１（例えば８０分）経過毎に除霜運転が開始され、所定ないし所要時間除霜運転が実行される。
【００４２】
さらに、図４〜図６に示すように、外気温度Ｔ０が、Ｔ０＜−１０℃を充足したとき、または室外熱交温度ＴＥが、ＴＥ＜−１６℃を充足したとき、あるいは室外熱交温度最低値ＴＥ０が、ＴＥ０＜−１３℃を充足したときには、Ｅゾーンに入り、除霜間隔時間Ｔ１は例えば８０分から１５０分に延長され、暖房起動時等から１５０分経過毎に除霜運転が開始される。
【００４３】
そして、除霜運転制御手段１６ａは、コンプレッサ２の吐出温度の推定を、室内熱交温度センサ１２により検出された検出値、室外熱交温度センサ９により検出された検出値、コンプレッサ２の運転周波数（Ｈｚ）の関数により算出する機能を有する。したがって、コンプレッサ２の吐出温度を検出する温度センサを省略することができる。
【００４４】
なお、コンプレッサ２の吐出温度Ｔｄについては以下の通り推定することができる。
【００４５】
まず、コンプレッサ２の吐出温度Ｔｄはコンプレッサ２の圧縮行程を理想気体のポリトロープ変化と考えると、次の（１）式の状態式で算出することができる。
【００４６】
【数１】

【００４７】
上記（１）式の吐出温度Ｔｄを得るためには、コンプレッサ２の吐出圧力Ｐｄ、コンプレッサの吸込圧力Ｐｓおよびコンプレッサの吸込温度Ｔｓが必要である。しかし、圧力センサは高価で、かつ、大形であるため実際的ではない。そこで、大雑把ではあるが、コンプレッサ２の吐出圧力を凝縮温度Ｔｃからの圧力変換＋圧損分ΔＰｄと見做し、また、コンプレッサ２の吸込圧力を蒸発温度Ｔｅからの圧力変換＋圧損分ΔＰｄと見做すことにより、コンプレッサ２の吐出圧力Ｐｄを凝縮器の温度Ｔｃの関数として次の（２）式で演算する。
【００４８】
【数２】

【００４９】
コンプレッサ２の吸込圧力Ｐｓを蒸発器の温度Ｔｅの関数として次の（３）式で演算する。
【００５０】
【数３】

【００５１】
コンプレッサ２の吸込温度Ｔｓを蒸発器の温度Ｔｅの関数として次の（４）式で演算することができる。
【００５２】
【数４】

【００５３】
したがって、これらの演算結果に基づいて、コンプレッサ２の吐出温度Ｔｄを次の（５）式によって推定することができるる。
【００５４】
【数５】

【００５５】
上記（２）〜（４）式中の係数または定数ａ〜ｅは実験的に近似値を決定することが可能である。また、ポリトロープ指数ｎおよび固定値αも実験的に決めることができる。なお、コンプレッサ２の吐出側の圧力Ｐｄと凝縮器の温度Ｔｃとはほぼ比例関係にあるため、係数ａは正の値をとる。
【００５６】
また、インバータ回路１８によってコンプレッサ２の回転速度を制御するものにおいても同様に（５）式によりコンプレッサ２の吐出温度Ｔｄを推定することが可能であるが、コンプレッサ２の回転速度の変化によって冷媒流量が変化し、Ｐｄ＝Ｗ（Ｔｃ）と、Ｐｓ＝Ｋ（Ｔｅ）に影響を及ぼすため、さらに、インバータ回路１８の出力周波数ＨｚをＰｄ，Ｐｓの演算要素として加えることにより、吐出温度Ｔｄをより正確に推定することが可能となる。
【００５７】
この場合、吐出圧Ｐｄを次の（６）式で演算し、
【数６】

【００５８】
吸込圧力Ｐｓを次の（７）式で演算することができる。
【００５９】
【数７】

【００６０】
したがって、これらの演算結果に基づいて、コンプレッサ２の吐出温度Ｔｄを次の（８）式によって推定することができる。
【００６１】
【数８】

【００６２】
なお、上記（６），（７）式中の係数または定数ａ1 ，ｂ1 ，ｚ，ｃ1 ，ｄ1 ，ｘは実験的に求めることができる。
【００６３】
また、冷媒流量はコンプレッサ２の吸込圧力Ｐｓへの影響が少ないため、コンプレッサ２の吐出圧力Ｐｄについてのみインバータ回路１８の出力周波数Ｈｚを加味してコンプレッサ２の吐出温度Ｔｄを次の（９）式によって推定することもできる。
【００６４】
【数９】

【００６５】
以上、（５），（８），（９）式のいずれかの関係式を用いてコンプレッサ２の吐出温度の推定を行なうことができるものであり、制御部のマイクロコンピュータによって逐次演算すればよい。
【００６６】
図７はこの除霜運転制御手段１６ａにより空気調和機１を除霜運転する場合の作用を示すグラフであり、外気温度Ｔ０が−８℃で暖房起動あるいは除霜復帰（以下単に暖房起動等という）したときの短配管時の暖房起動から除霜運転開始周辺までのコンプレッサ２の吐出温度とその推定値の変動を、図１０で示す従来例と時間軸（横軸）を一致させて対応して示している。
【００６７】
すなわち、図７と図１０とに示すように、本実施形態と従来例と共に、室外熱交換器６の着霜が増えるに従って、この室外熱交換器６の熱交換機能が低下し、蒸発量が減少するので、コンプレッサ２への冷媒の液バック量が増加する。
【００６８】
これを防止するために、電子膨張弁５の開度が徐々に絞られ、室内熱交換器４への冷媒ホールド量が増加していく。従来の低下量検出方式に基づくＡ，Ｂ，Ｃゾーンでは、これらのゾーンにそれぞれ入る前に、室内熱交温度センサ１２の位置が過冷却状態になり、吐出温度を低目に推定してしまうので、コンプレッサ２の運転周波数が順次上昇させられてケースサーモ動作による異常停止に至ってしまう。
【００６９】
しかし、本実施形態では、室外熱交温度最低値ＴＥ０と室外熱交温度ＴＥとの差（ＴＥ０−ＴＥ）の如何に拘らず、除霜間隔時間Ｔ１の例えば８０分（または１５０分）経過時毎に除霜運転に入るので、室内熱交温度センサ１２の位置が過冷却状態に至る前に、除霜運転に入ることができる。このために、コンプレッサ２のケースサーモによる異常停止を未然に防止することができ、暖房運転を継続することができるので、暖房効率の向上を図ることができる。しかも、吐出温度センサを省略することができるので、コスト低減を図ることができる。
【００７０】
そして、図８で示す従来方式では、例えば外気温度が−５℃で暖房起動したときには、室外熱交温度最低値ＴＥ０が−８℃で、室外熱交温度ＴＥが−１０．５℃に到達し、その状態が３分間継続したときに、Ａゾーンに入って、除霜運転が開始される。
【００７１】
しかし、長配管接続や冷媒量不足の暖房起動時には、室外熱交温度最低値ＴＥ０が低下し、さらに、この最低値ＴＥ０が低下し、さらに、この最低値ＴＥ０検出後に外気温度Ｔ０が上昇した場合には、室外熱交温度ＴＥも高くなるので、これら両者の低下量（ＴＥ０−ＴＥ）が小さくなり、従来の低下量方式に基づくＡ，Ｂ，Ｃゾーンに入りにくくなり、除霜運転が開始されにくくなる。
【００７２】
このために、Ａ〜Ｃゾーンしかない従来例では室外熱交換器６の着霜過剰による暖房能力低下をきたすが、本実施形態ではかかる低下量（ＴＥ０−ＴＥ）の如何に拘らず、除霜間隔時間Ｔ１経過毎に除霜運転を実行することができるので、室外熱交換器６の着霜過剰を有効に防止することができる。その結果、室外熱交換器の着霜過剰に起因する圧縮機のケースサーモによる異常停止を防止ないし低減することができる。
【００７３】
【発明の効果】
以上説明したように本発明によれば、低外気温の暖房運転時に所定時間経過毎に除霜運転を行なうので、吐出温度センサがなくてもコンプレッサのケースサーモによる異常停止に至らず運転を継続できると共に、除霜運転開始の遅れに伴う着霜過剰による暖房能力低下を防止できる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る除霜運転開始ゾーン（領域）をそれぞれ示す図。
【図２】本発明の一実施形態に係る空気調和機の冷凍サイクル図。
【図３】図１，図２で示す実施形態の制御系の全体構成を示すブロック図。
【図４】図１，図２で示す実施形態の外気温度によりＤ，Ｅゾーンを充足させるための条件を示す図。
【図５】図１，図２で示す実施形態の室外熱交温度によりＤ，Ｅゾーンを充足させるための条件を示す図。
【図６】図１，図２で示す実施形態の室外熱交温度最低値によりＤ，Ｅゾーンを充足させるための条件を示す図。
【図７】図１，図２で示す実施形態の作用を示すグラフ。
【図８】従来の除霜運転開始ゾーン（領域）をそれぞれ示す図。
【図９】従来の各除霜運転開始ゾーン（領域）に入るための条件を示す図。
【図１０】図８，図９で示す従来例の暖房運転時の作用を示すグラフ。
【符号の説明】
１空気調和機
２コンプレッサ
３四方弁
４室内熱交換器
６室外熱交換器
９室外熱交温度センサ
１０外気温センサ
１１室温センサ
１２室内熱交温度センサ
１５室外制御部
１６室内制御部
１６ａ除霜運転制御手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat pump type air conditioner having a control means for performing a defrosting operation during heating operation, and in particular, provided with a defrosting operation control means for starting the defrosting operation every predetermined time during the heating operation. Related to air conditioners.
[0002]
[Prior art]
Generally, in this type of heat pump type air conditioner, a defrosting operation in which the outdoor heat exchanger acts as a condenser by reversing the direction of refrigerant circulation in the refrigeration cycle by switching the four-way valve during heating operation. It is possible to defrost the outdoor heat exchanger. However, at the time of heating operation at a low outside air temperature, the heating capacity decline due to excessive frost formation of the outdoor heat exchanger, and the operating frequency of the compressor (the number of revolutions per unit time) increased to compensate for this heating capacity decline. There is a case where a case thermo abnormality of the compressor is caused due to an increase in discharge temperature accompanying the increase.
[0003]
Conventional air conditioners respond to these issues as follows.
[0004]
(1) For excessive frosting of the outdoor heat exchanger, when the defrosting operation start condition set by the so-called reduction amount detection method shown in FIG. 8 is satisfied, the defrosting operation is performed during the heating operation. Control means for starting is provided.
[0005]
This decrease amount detection method is performed after a predetermined time (for example, 10 minutes) has elapsed since the start of heating or when the defrosting operation is returned to the heating operation (0 hours in FIG. 8) and the cycle temperature has stabilized, for example, for a predetermined time (for example, The minimum value TE0 when the temperature of the outdoor heat exchanger (hereinafter referred to as the outdoor heat exchange temperature TE) has fallen the most in the outdoor heat exchange temperature minimum value TE0 detection time for 5 minutes is detected, and the outdoor with respect to this minimum value TE0 is detected. In accordance with the heat exchanger temperature TE and the amount of decrease (TE0-TE), the regions where the defrosting operation is started are set in, for example, three zones A, B, and C as shown in FIG. . When the difference between the outdoor heat exchange temperature TE or the heat exchange temperature minimum value TE0 reaches any of the A, B, and C zones, and the arrival continues for a predetermined time (for example, 3 minutes). The defrosting operation is started.
[0006]
(2) On the other hand, a discharge temperature sensor for detecting the discharge temperature of the compressor is provided for an increase in the discharge temperature, and when the predetermined discharge temperature rise is detected by this discharge temperature sensor, the operating frequency of the compressor is lowered. It is configured to prevent the compressor case thermo abnormality.
[0007]
On the other hand, there is a discharge temperature estimation method in which no discharge temperature sensor is provided. In this method, the discharge temperature is estimated from both the detected temperature by the indoor heat exchange temperature sensor and the outdoor heat exchange temperature sensor and a function of the operating frequency of the compressor, and corresponds to the increase in the discharge temperature.
[0008]
[Problems to be solved by the invention]
However, the conventional example in which the discharge temperature sensor is provided as described above has a problem that the cost is increased accordingly.
[0009]
In addition, in the discharge temperature estimation method in which the discharge temperature sensor is not provided as described above, the temperature detected by the indoor heat exchange temperature sensor may become too low when the refrigerant pipe through which the refrigerant circulates is short and connected to a short pipe. .
[0010]
That is, as shown in FIG. 10, when the amount of frost formation on the outdoor heat exchanger increases, the amount of refrigerant evaporated in the outdoor heat exchanger decreases, and accordingly, the amount of liquid back to the compressor increases accordingly. . In order to prevent this, the electronic expansion valve is throttled and the refrigerant hold amount to the indoor heat exchanger increases, so that the supercooling state is reached at the position of the indoor heat exchanger temperature sensor. For this reason, since the discharge temperature is estimated to be low, there is a problem that an abnormal stop is caused by the case thermostat of the compressor.
[0011]
Furthermore, in the case of a decrease in the minimum value TE0 of the outdoor heat exchange temperature TE due to a long pipe connection or a shortage of refrigerant, a change in the outdoor air condition after the detection of the minimum value TE0, etc., the difference between these TE and this and TE0 is There is a problem that it is difficult to enter the defrosting start areas A, B, and C and the defrosting operation is difficult to start, resulting in a decrease in heating capacity due to excessive frost formation.
[0012]
The present invention has been made in consideration of such circumstances, and its purpose is to provide an abnormal stoppage due to the case thermostat of the compressor and the heating capacity due to excessive frosting of the outdoor heat exchanger regardless of the presence or absence of the discharge temperature sensor. It is in providing the air conditioner which can prevent the fall of this.
[0013]
[Means for Solving the Problems]
According to the first to third aspects of the present invention, the outdoor heat exchanger temperature, which is the temperature of the outdoor heat exchanger during the heating operation, reaches the predetermined first defrosting region, and the outdoor in a predetermined time after heating activation or defrosting recovery In the air conditioner having a control means for starting the defrosting operation when the lowering value, which is the difference between the lowest value of the heat exchange temperature and the outdoor heat exchange temperature, is equal to or higher than a predetermined value, in the control means, When any one of the outdoor heat exchange temperature, the minimum value of the outdoor heat exchange temperature, or the outside air temperature reaches the predetermined second defrost region, the defrosting operation is performed when the heating is started or removed. An air conditioner provided with a defrosting operation control means that starts every predetermined time from the time of frost recovery.
[0014]
According to the present invention, during the heating operation, when the outdoor heat exchange temperature reaches the first defrosting region, or when the outdoor heat exchange temperature is the difference between the outdoor heat exchange temperature and the minimum value within the predetermined time, the decrease value is predetermined. When the value is greater than or equal to the value, the defrosting operation is started.
[0015]
On the other hand, when any one of the outside air temperature, the outdoor heat exchange temperature, and the minimum value thereof reaches the second defrosting region, every elapse of a predetermined time from the heating start-up or the defrosting operation return (hereinafter referred to as heating start-up). Then, the defrosting operation is started. That is, a defrosting start condition for performing a defrosting operation every predetermined time is set in parallel with the conventional reduction amount detection method.
[0016]
Therefore, when any of the outdoor heat exchange temperature, its minimum value, and the outside air temperature reaches the second predetermined area, the defrosting operation is started. In addition, after that, the minimum value of the outdoor heat exchange temperature decreases when a long pipe is connected or when the heating is started due to a shortage of the refrigerant. When the temperature becomes higher, the temperature difference (TE0-TE) is reduced and the decrease value tends to be less than or equal to the predetermined value. Since the defrosting operation is started every time, the excessive frosting of the outdoor heat exchanger can be prevented in advance. For this reason, the raise of the operating frequency of the compressor by excessive frost formation can be suppressed.
[0017]
Therefore, once the defrosting operation is started in the second defrosting region, the defrosting operation is started every time a predetermined time elapses, so that the compressor case thermo abnormality may occur even without the discharge temperature sensor. The heating operation can be continued. That is, since the discharge temperature sensor can be omitted, the cost can be reduced accordingly.
[0018]
According to a fourth aspect of the present invention, the defrosting operation control means has a function of controlling the predetermined time for starting the defrosting operation every predetermined time in accordance with the outside air temperature. The air conditioner according to any one of

Items

3 and 5, wherein the predetermined time is lengthened as the outside air temperature decreases.
[0019]
According to these inventions, the predetermined time for starting the defrosting operation every predetermined time is controlled according to the outside air temperature. Therefore, even if there is no discharge temperature sensor, the case thermostat abnormality of the compressor does not occur and the heating operation is performed. Can continue.
[0020]
The invention of claim 6 is characterized in that the defrosting operation control means has a function of controlling the predetermined time for starting the defrosting operation every elapse of a predetermined time according to the outdoor heat exchange temperature. In the air conditioner described above, the predetermined time is increased as the outdoor heat exchange temperature decreases.
[0021]
According to these inventions, since the predetermined time for starting the defrosting operation every predetermined time is controlled according to the outdoor heat exchange temperature, the heater does not cause the compressor case thermo abnormality even without the discharge temperature sensor. Driving can be continued.
[0022]
The invention of claim 8 has a function of controlling the defrosting operation control means to lengthen the predetermined time for starting the defrosting operation every predetermined time as the minimum value of the outdoor heat exchange temperature becomes lower. It is an air conditioner in any one of Claim 1 thru | or 3 characterized by these.
[0023]
According to the present invention, the predetermined time for starting the defrosting operation every predetermined time is controlled according to the minimum value of the outdoor heat exchange temperature. Therefore, even if there is no discharge temperature sensor, the case thermo abnormality of the compressor is reached. The heating operation can be continued.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[0025]
FIG. 2 is a refrigeration cycle diagram of the air conditioner 1 according to one embodiment of the present invention. The air conditioner 1 includes a compressor 2, a four-way valve 3 having a refrigerant flow switching function, an indoor heat exchanger 4 having an indoor fan 4a, an electronic control valve (PMV) 5 as an expansion valve, and an outdoor fan 6a. The outdoor heat exchanger 6 is communicated sequentially and annularly through the refrigerant pipe 7 to constitute a refrigeration cycle for reversibly circulating the refrigerant.
[0026]
As the refrigerant, an alternative refrigerant having a higher saturation pressure at the same temperature than R22, for example, a saturation pressure at 50 ° C. of 2500 kPa or more is used. In addition, as such an alternative refrigerant that does not particularly destroy the ozone layer, R32 (CH ₂ F ₂ ) And R125 (CHF ₂ CF _Three ) With a composition of 80% or more, R143a (CH _Three CF _Three ) And a refrigerant having a synthetic composition of 80% or more, and R32 (CH ₂ F ₂ ) And the like having a composition of 45% or more.
[0027]
Then, the air conditioner 1 controls the refrigerant 2 → the four-way valve 3 → the outdoor heat exchanger as indicated by the solid arrow in the figure by switching control of the four-way valve 3 during the operation of the indoor fan 4a and the outdoor fan 6a. (Condensation action) 6 → Expansion valve (PMV) 5 → Indoor heat exchanger (evaporation action) 4 → Four-way valve 3 → Cooling operation by circulating to compressor 2 Compressor 2 → four-way valve 3 → indoor heat exchanger (condensing action) 4 → expansion valve 5 → outdoor heat exchanger (evaporating action) 6 → four-way valve 3 → circulated to compressor 2 for heating operation Yes.
[0028]
Furthermore, by stopping the indoor fan 4a and the outdoor fan 6a during the heating operation and controlling the switching of the four-way valve 3, the refrigerant is circulated in the direction opposite to the circulation direction during heating (indicated by the solid arrow). The defrosting operation is performed by causing the outdoor heat exchanger to condense.
[0029]
The compressor 2, the four-way valve 3, the PMV 5, the outdoor heat exchanger 6, and the outdoor fan 6a are provided in an outdoor unit that is installed outdoors. Further, the outdoor unit is installed in the outdoor heat exchanger 6 to detect the temperature of the outdoor heat exchanger 6, the outdoor heat exchanger temperature sensor 9, the outdoor heat exchanger 6 itself, or the outdoor heat exchanger. 6 is provided with an outside air temperature sensor 10 provided in the vicinity of 6 for detecting the outside air temperature.
[0030]
The indoor heat exchanger 4 and the indoor fan 4a are provided in an indoor unit 13 installed indoors. The indoor unit 13 includes a room temperature sensor 11 that detects the indoor temperature, and an indoor heat exchanger temperature sensor 12 that is installed in the indoor heat exchanger 4 and detects the refrigerant condensing temperature of the indoor heat exchanger 4. Yes.
[0031]
FIG. 3 shows a control system of the entire air conditioner 1 including the indoor unit 13 and the outdoor unit 14. The outdoor unit 14 includes an outdoor control unit 15 on which, for example, a microcomputer is mounted. The outdoor control unit 15 includes an EEPROM 15a as a memory for storing information data necessary for the control. The outdoor control unit 15 includes an indoor control unit 16 via an AC power supply line La and a communication line Lb. Are connected to the power supply to enable bidirectional communication.
[0032]
The outdoor control unit 15 includes an outdoor heat exchanger temperature sensor 9, an outdoor air temperature sensor 10, a fan drive circuit 17 for driving and controlling the fan motor 6b of the outdoor fan 6a, for example, a four-way valve (4V) 3 including an electromagnetic valve, An electronic expansion valve (PMV) 5 and an inverter circuit 18 for controlling the number of revolutions per unit time of the motor 2a by controlling the applied voltage applied to the motor 2 of the compressor 2 and its operating frequency are electrically connected to each other. is doing.
[0033]
On the other hand, the indoor unit 13 includes, for example, an indoor control unit 16 equipped with a microcomputer. An AC power supply 19 for power supply and a remote control 20 for remote operation control are connected to the indoor control unit 16.
[0034]
The indoor control unit 18 includes the room temperature sensor 11, the indoor heat exchanger temperature sensor 12, the speed control circuit 22 that controls the rotational speed of the fan motor (FM) 21 that rotates the indoor fan 4a, and the up / down air direction adjustment louver. A louver drive circuit 24 that is driven while controlling a rotation angle of a louver motor (RM) 23 that is rotated about a swing axis is electrically connected.
[0035]
And the indoor control part 16 is provided with the defrost operation control means 16a which starts a defrost operation, when predetermined | prescribed defrost operation start conditions are satisfied during heating operation.
[0036]
FIG. 1 is a schematic diagram showing the defrosting operation start conditions set by the defrosting operation control means 16a. As conditions for starting the defrosting operation during the heating operation, for example, five defrosting operation start zones (removal) Frost area) A, B, C, D, E are provided.
[0037]
These defrosting operation start zones A to E are two defrosting operation start zones C, which are first defrosting regions set based on the conventional so-called reduction amount detection method shown in FIGS. A defrosting operation start zone that forcibly executes the defrosting operation regardless of the amount of decrease at an extremely low temperature such as A and the outdoor heat exchange temperature of −20 ° C. or lower is newly set as an embodiment of the present invention. For example, the defrosting operation start zones D and E of the two defrosting areas which are two defrosting areas are added as parallel conditions.
[0038]
That is, as shown in FIG. 8 and FIG. 9, the defrosting operation start zone A is the outdoor heat at a predetermined time, for example, 10 to 15 minutes TE0 detection time after starting the heating or after returning from the defrosting operation to the heating operation. The difference (TE0-TE) between the minimum value TR0 of the temperature of the outdoor heat exchanger 6 (hereinafter referred to as the outdoor heat exchange temperature TE) detected by the cross temperature sensor 9 and the outdoor heat exchange temperature TE after this TE0 detection time, That is, it is a region where the defrosting operation is started when the decrease amount reaches a predetermined value, for example, 2.5 ° C. or more (TE0−TE ≧ 2.5 ° C.) and the state continues for 3 minutes.
[0039]
In the defrosting operation start zone B, when the outdoor heat exchange temperature TE continuously reaches a predetermined value, for example, −20 ° C. or lower (TE ≦ −20 ° C.) for 3 minutes, the defrosting operation is started. The frost operation start zone C is defrosted when the difference between the outdoor heat exchange temperature TE and the minimum value TE0 reaches a predetermined value of 3.0 ° C. or higher (TE0−TE ≧ 3.0 ° C.) continuously for 3 minutes. Driving is started.
[0040]
Therefore, for example, heating is started when the outdoor temperature T0 is 0 ° C., the outdoor heat exchange temperature minimum value TE0 in the 10 to 15 minutes after the start is −3 ° C., and the outdoor heat exchange temperature is 37 minutes after the start (34 + 3 minutes). When TE becomes −6 ° C. or less, the defrosting operation is started in the C zone. Furthermore, when heating is started at a relatively low outside temperature of −5 ° C., the outdoor heat exchange temperature minimum value TE0 is −8 ° C., and the outdoor heat exchange temperature TE is −10. When the temperature becomes 5 ° C. or lower, the defrosting operation is started in the A zone.
[0041]
On the other hand, as shown in FIGS. 4 to 6, in the defrosting operation start zone D according to the present embodiment, when the outside air temperature T0 satisfies, for example, −10 ≦ T0 <−5 ° C., or the outdoor heat exchange temperature TE is This is a region where the defrosting operation is started when −16 ≦ TE <−11 ° C. is satisfied, or when the outdoor heat exchange temperature minimum value TE0 satisfies −13 ≦ TE0 <−8 ° C. When reaching the D zone, the defrosting operation control means 16a causes the defrosting operation every time a predetermined defrosting interval time T1 (for example, 80 minutes) elapses from the start of heating or the return from the defrosting operation to the heating operation. Is started, and the defrosting operation is executed for a predetermined or required time.
[0042]
Further, as shown in FIGS. 4 to 6, when the outdoor air temperature T0 satisfies T0 <−10 ° C., or when the outdoor heat exchanger temperature TE satisfies TE <−16 ° C., or the outdoor heat exchanger temperature. When the minimum value TE0 satisfies TE0 <−13 ° C., it enters the E zone, and the defrosting interval time T1 is extended from 80 minutes to 150 minutes, for example, and the defrosting operation is started every 150 minutes from the start of heating. Is done.
[0043]
The defrosting operation control means 16a estimates the discharge temperature of the compressor 2 by detecting the detected value detected by the indoor heat exchanger temperature sensor 12, the detected value detected by the outdoor heat exchanger temperature sensor 9, and the operating frequency of the compressor 2. It has a function of calculating with a function of (Hz). Therefore, the temperature sensor for detecting the discharge temperature of the compressor 2 can be omitted.
[0044]
The discharge temperature Td of the compressor 2 can be estimated as follows.
[0045]
First, the discharge temperature Td of the compressor 2 can be calculated by the following equation (1) when the compression stroke of the compressor 2 is considered as a change in the ideal gas polytrope.
[0046]
[Expression 1]

[0047]
In order to obtain the discharge temperature Td of the above equation (1), the discharge pressure Pd of the compressor 2, the compressor suction pressure Ps, and the compressor suction temperature Ts are required. However, the pressure sensor is not practical because it is expensive and large. Thus, roughly, the discharge pressure of the compressor 2 is regarded as pressure conversion from the condensation temperature Tc + pressure loss ΔPd, and the suction pressure of the compressor 2 is regarded as pressure conversion from the evaporation temperature Te + pressure loss ΔPd. As a result, the discharge pressure Pd of the compressor 2 is calculated by the following equation (2) as a function of the condenser temperature Tc.
[0048]
[Expression 2]

[0049]
The suction pressure Ps of the compressor 2 is calculated by the following equation (3) as a function of the evaporator temperature Te.
[0050]
[Equation 3]

[0051]
The suction temperature Ts of the compressor 2 can be calculated by the following equation (4) as a function of the evaporator temperature Te.
[0052]
[Expression 4]

[0053]
Therefore, based on these calculation results, the discharge temperature Td of the compressor 2 can be estimated by the following equation (5).
[0054]
[Equation 5]

[0055]
The coefficients or constants a to e in the above equations (2) to (4) can be experimentally determined as approximate values. Also, the polytropic index n and the fixed value α can be determined experimentally. Since the pressure Pd on the discharge side of the compressor 2 and the condenser temperature Tc are substantially proportional, the coefficient a takes a positive value.
[0056]
Similarly, in the case where the rotation speed of the compressor 2 is controlled by the inverter circuit 18, the discharge temperature Td of the compressor 2 can be similarly estimated by the equation (5), but the refrigerant flow rate is changed by the change in the rotation speed of the compressor 2. Changes, and affects Pd = W (Tc) and Ps = K (Te). Further, by adding the output frequency Hz of the inverter circuit 18 as an arithmetic element of Pd and Ps, the discharge temperature Td is further increased. It is possible to estimate accurately.
[0057]
In this case, the discharge pressure Pd is calculated by the following equation (6):
[Formula 6]

[0058]
The suction pressure Ps can be calculated by the following equation (7).
[0059]
[Expression 7]

[0060]
Therefore, based on these calculation results, the discharge temperature Td of the compressor 2 can be estimated by the following equation (8).
[0061]
[Equation 8]

[0062]
The coefficients or constants a1, b1, z, c1, d1, and x in the above equations (6) and (7) can be obtained experimentally.
[0063]
Further, since the refrigerant flow rate has little influence on the suction pressure Ps of the compressor 2, the discharge temperature Td of the compressor 2 is calculated by the following equation (9) by taking into account the output frequency Hz of the inverter circuit 18 only for the discharge pressure Pd of the compressor 2. Can also be estimated.
[0064]
[Equation 9]

[0065]
As described above, the discharge temperature of the compressor 2 can be estimated using any one of the relational expressions (5), (8), and (9), and may be sequentially calculated by the microcomputer of the control unit. .
[0066]
FIG. 7 is a graph showing the operation when the air conditioner 1 is defrosted by the defrosting operation control means 16a. When the outside air temperature T0 is −8 ° C., heating activation or defrosting recovery (hereinafter simply referred to as heating activation or the like) is performed. 10), the discharge temperature of the compressor 2 from the start of heating in the short pipe to the vicinity of the start of the defrosting operation and the fluctuation of the estimated value are matched by matching the time axis (horizontal axis) with the conventional example shown in FIG. It shows.
[0067]
That is, as shown in FIGS. 7 and 10, together with the present embodiment and the conventional example, as the frost formation of the outdoor heat exchanger 6 increases, the heat exchange function of the outdoor heat exchanger 6 decreases and the evaporation amount decreases. Since it decreases, the liquid back amount of the refrigerant to the compressor 2 increases.
[0068]
In order to prevent this, the opening degree of the electronic expansion valve 5 is gradually reduced, and the refrigerant hold amount to the indoor heat exchanger 4 increases. In the A, B, and C zones based on the conventional drop amount detection method, the position of the indoor heat exchange temperature sensor 12 becomes supercooled before entering each of these zones, and the discharge temperature is estimated to be low. As a result, the operating frequency of the compressor 2 is sequentially increased, leading to an abnormal stop due to the case thermo-operation.
[0069]
However, in this embodiment, for example, when the defrosting interval time T1 is 80 minutes (or 150 minutes), regardless of the difference (TE0-TE) between the minimum outdoor heat exchange temperature TE0 and the outdoor heat exchange temperature TE. Since the defrosting operation is started every time, the defrosting operation can be started before the indoor heat exchanger temperature sensor 12 reaches the supercooled state. For this reason, the abnormal stop by the case thermostat of the compressor 2 can be prevented in advance, and the heating operation can be continued, so that the heating efficiency can be improved. In addition, since the discharge temperature sensor can be omitted, the cost can be reduced.
[0070]
In the conventional system shown in FIG. 8, for example, when heating is started at an outdoor temperature of −5 ° C., the outdoor heat exchange temperature minimum value TE0 is −8 ° C., and the outdoor heat exchange temperature TE reaches −10.5 ° C. When the state continues for 3 minutes, the A zone is entered and the defrosting operation is started.
[0071]
However, when long piping is connected or when heating is started with a shortage of refrigerant, the outdoor heat exchange temperature minimum value TE0 decreases, the minimum value TE0 decreases, and the outdoor air temperature T0 increases after detection of the minimum value TE0. Since the outdoor heat exchange temperature TE is also high, the reduction amount (TE0-TE) of both of them becomes small, it becomes difficult to enter the A, B, C zone based on the conventional reduction amount method, and the defrosting operation is started. It becomes difficult to be done.
[0072]
For this reason, in the conventional example having only the A to C zones, the heating capacity is reduced due to excessive frost formation of the outdoor heat exchanger 6, but in this embodiment, defrosting is performed regardless of the reduction amount (TE0-TE). Since the defrosting operation can be executed every time interval T1 elapses, excessive frosting of the outdoor heat exchanger 6 can be effectively prevented. As a result, it is possible to prevent or reduce an abnormal stop due to the case thermostat of the compressor due to excessive frost formation in the outdoor heat exchanger.
[0073]
【The invention's effect】
As described above, according to the present invention, the defrosting operation is performed every predetermined time during the heating operation at the low outside air temperature, so that the operation is not stopped due to the case thermostat of the compressor without the discharge temperature sensor. In addition, it is possible to prevent a decrease in heating capacity due to excessive frost formation accompanying a delay in starting the defrosting operation.
[Brief description of the drawings]
FIG. 1 is a diagram showing a defrosting operation start zone (region) according to an embodiment of the present invention.
FIG. 2 is a refrigeration cycle diagram of an air conditioner according to an embodiment of the present invention.
FIG. 3 is a block diagram showing the overall configuration of the control system of the embodiment shown in FIGS. 1 and 2;
4 is a diagram showing conditions for satisfying D and E zones according to the outside air temperature of the embodiment shown in FIGS. 1 and 2. FIG.
5 is a diagram showing conditions for satisfying D and E zones by the outdoor heat exchange temperature of the embodiment shown in FIGS. 1 and 2. FIG.
6 is a diagram showing conditions for satisfying the D and E zones with the lowest outdoor heat exchange temperature value of the embodiment shown in FIGS. 1 and 2. FIG.
7 is a graph showing the operation of the embodiment shown in FIGS. 1 and 2. FIG.
FIG. 8 is a diagram showing a conventional defrosting operation start zone (region).
FIG. 9 is a diagram showing conditions for entering each conventional defrosting operation start zone (area).
FIG. 10 is a graph showing the operation during heating operation of the conventional example shown in FIGS. 8 and 9;
[Explanation of symbols]
1 Air conditioner
2 Compressor
3 Four-way valve
4 indoor heat exchangers
6 Outdoor heat exchanger
9 Outdoor heat exchange temperature sensor
10 Outside air temperature sensor
11 Room temperature sensor
12 Indoor heat exchange temperature sensor
15 Outdoor control unit
16 Indoor control unit
16a Defrosting operation control means

Claims

The outdoor heat exchanger temperature, which is the temperature of the outdoor heat exchanger during heating operation, reaches the predetermined first defrosting region, and the minimum value of the outdoor heat exchanger temperature in a predetermined time after heating activation or defrosting recovery and the above-mentioned outdoor In an air conditioner having control means for starting a defrosting operation when a drop value, which is a difference from the heat exchange temperature, exceeds a predetermined value, the outdoor heat exchange temperature is set in advance in the control means. An air conditioner provided with a defrosting operation control means for starting a defrosting operation every predetermined time from the time of starting the heating or defrosting when reaching the defrosting area of 2 .

The outdoor heat exchanger temperature, which is the temperature of the outdoor heat exchanger during heating operation, reaches the predetermined first defrosting region, and the minimum value of the outdoor heat exchanger temperature in the predetermined time after heating activation or defrosting recovery is In an air conditioner having a control means for starting a defrosting operation when a drop value, which is a difference from the heat exchange temperature, exceeds a predetermined value, the minimum value of the outdoor heat exchanger is previously set in the control means. Defrosting operation control means is provided for starting the defrosting operation every predetermined time from the time of starting the heating or defrosting when reaching the defined second defrosting region. Air conditioner.

The outdoor heat exchanger temperature, which is the temperature of the outdoor heat exchanger during heating operation, reaches the predetermined first defrosting region, and the minimum value of the outdoor heat exchanger temperature in a predetermined time after heating activation or defrosting recovery and the above-mentioned outdoor In an air conditioner having a control means for starting a defrosting operation when a decrease value, which is a difference from the heat exchange temperature, is equal to or greater than a predetermined value, the control means is provided with a second removal temperature determined in advance. An air conditioner provided with a defrosting operation control means for starting a defrosting operation every predetermined time from the time of starting the heating or defrosting when reaching the frost region.

The defrosting operation control means has a function of controlling the predetermined time for starting the defrosting operation every predetermined time according to the outside air temperature. Air conditioner.

The air conditioner according to claim 4, wherein the predetermined time is lengthened as the outside air temperature decreases.

The air conditioner according to claim 1, wherein the defrosting operation control means has a function of controlling the predetermined time for starting the defrosting operation every elapse of a predetermined time according to the outdoor heat exchange temperature.

The air conditioner according to claim 6, wherein the predetermined time is lengthened as the outdoor heat exchange temperature decreases.

The defrosting operation control means has a function of controlling the defrosting operation to start longer every elapse of a predetermined time as the minimum value of the outdoor heat exchange temperature becomes lower. The air conditioner described.