JP4067428B2

JP4067428B2 - Air conditioner and control method of air conditioner

Info

Publication number: JP4067428B2
Application number: JP2003056588A
Authority: JP
Inventors: 亮太平田; 憲史門間; 大成野口; 善郎後藤
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2003-03-04
Filing date: 2003-03-04
Publication date: 2008-03-26
Anticipated expiration: 2023-03-04
Also published as: JP2004263975A

Description

【０００１】
【発明の属する技術分野】
本発明は、室外ユニットと室内ユニットとが高圧ガス管、低圧ガス管及び液管を有するユニット配管により接続された空気調和装置及び空気調和装置の制御方法に関する。
【０００２】
【従来の技術】
一般に、圧縮機と室外熱交換器とを有する室外ユニットと、室内熱交換器を有する複数台の室内ユニットとを高圧ガス管、低圧ガス管及び液管を有するユニット間配管で接続し、各室内熱交換器の一端と高圧ガス管とを接続する高圧ガス分岐管に配設される第１開閉弁と、各室内熱交換器の一端と低圧ガス管とを接続する低圧ガス分岐管に配設される第２開閉弁と、各室内熱交換器の他端と液管との間に配設される冷媒減圧器と、低圧ガス分岐管に並列接続され低圧ガス分岐管よりも流路抵抗の大きいバイパス管に配設される第３開閉弁とを有し、室内ユニット毎に冷房運転或いは暖房運転を行えるように構成した空気調和装置が知られている（例えば、特許文献１参照。）。
【０００３】
このような空気調和装置において、室内ユニットが暖房運転から冷房運転に切り換える際に、室内ユニット側の開閉弁の開閉操作により、暖房運転時に凝縮器として作用していた室内熱交換器が、冷房運転切換時に蒸発器に切り換えられるために、室内熱交換器内で急激な圧力変化が発生することになる。この圧力変化が原因で室内熱交換器或いは開閉弁付近で著しい冷媒音が発生することがあった。
【０００４】
そこで、従来は、室内ユニットを暖房運転から冷房運転に切り換える際に、室内熱交換器内の冷媒圧力を飽和圧力に近づけるべく、当該室内ユニット側の第１開閉弁、第２開閉弁、第３開閉弁及び冷媒減圧器を一定時間（例えば、６０［ｓｅｃ］）に亘って閉じ、次いで、室内熱交換器内の圧力を低圧ガス管側の圧力に近づけるべく、第３開閉弁のみを一定時間（例えば、１８０［ｓｅｃ］）に亘って開き、次いで、第２開閉弁を開いて、通常の冷房運転を行うことにより、冷媒音を回避していた。
【０００５】
【特許文献１】
特許第２８０４５２７号公報
【０００６】
【発明が解決しようとする課題】
しかしながら、上記空気調和装置では、開閉弁の操作を予め設定した時間で行っているため、既に室内熱交換器内の圧力が冷媒音を回避できる圧力にまで低下している場合であっても、一定時間が経過するまで冷房運転に移行するのを待たなければならず、効率的でないという問題がある。
【０００７】
本発明の目的は、上述の事情を考慮してなされたものであり、効率よく冷媒音の発生を抑制することができる空気調和装置及び空気調和装置の制御方法を提供することにある。
【０００８】
【課題を解決するための手段】
上記課題を解決するため、圧縮機と室外熱交換器とを有する室外ユニットと、室内熱交換器を有する複数台の室内ユニットとを高圧ガス管、低圧ガス管及び液管を有するユニット間配管で接続し、各室内熱交換器の一端と前記高圧ガス管との間に配設される第１開閉弁と、各室内熱交換器の一端と前記低圧ガス管との間に配設される第２開閉弁と、各室内熱交換器の他端と前記液管との間に配設される冷媒減圧器とを有し、室内ユニット毎に冷房運転或いは暖房運転を行えるように構成した空気調和装置において、各室内ユニットの前記室内熱交換器の一端側に第１温度センサを設けるとともに、他端側に第２温度センサを設け、前記室内ユニットを暖房運転から冷房運転に切り換える際に、当該室内ユニット側の第１開閉弁、第２開閉弁及び冷媒減圧器を閉鎖する閉鎖手段と、この閉鎖手段により第１開閉弁、第２開閉弁及び冷媒減圧器を閉鎖してから室内熱交換器内の冷媒圧力が飽和圧力となるのに十分な長さの第１の所定時間が経過した場合、冷房運転を開始するに先立って、前記閉鎖手段により閉鎖された第２開閉弁を開放する開放手段と、前記第１の所定の時間が経過する前に、当該室内ユニットの第１温度センサにより検出された温度と第２温度センサにより検出された温度との差温が第１の所定値以下となった場合、前記第１の所定の時間を計時するタイマを強制的にタイムアップさせて、前記開放手段により前記第２開閉弁を開放させるタイムアップ手段とを備えたことを特徴とするものである。
【０００９】
この場合において、前記開放手段により第２開閉弁を開放する直前に当該室内ユニットの第１温度センサにより検出された温度と当該室内ユニットの第１温度センサにより検出された現在の温度との差温が、当該室内ユニットの室内熱交換器と前記低圧ガス管とが略均圧状態となる第２の所定値以上となった場合、冷房運転を開始する手段を備えてもよい。
【００１０】
この場合において、前記開放手段により第２開閉弁を開放する直前に当該室内ユニットの第１温度センサにより検出された温度と当該室内ユニットの第１温度センサにより検出された現在の温度との差温が、当該室内ユニットの室内熱交換器と前記低圧ガス管とが略均圧状態となる第２の所定値以上となる前に、室内熱交換器と低圧ガス管とが略均圧状態となるのに十分な長さの第２の所定の時間が経過した場合、冷房運転を開始してもよい。
【００１１】
また、圧縮機と室外熱交換器とを有する室外ユニットと、室内熱交換器を有する複数台の室内ユニットとを高圧ガス管、低圧ガス管及び液管を有するユニット間配管で接続し、各室内熱交換器の一端と前記高圧ガス管とを接続する高圧ガス分岐管に配設される第１開閉弁と、各室内熱交換器の一端と前記低圧ガス管とを接続する低圧ガス分岐管に配設される第２開閉弁と、各室内熱交換器の他端と前記液管との間に配設される冷媒減圧器と、前記低圧ガス分岐管に並列接続され前記低圧ガス分岐管よりも流路抵抗の大きいバイパス管に配設される第３開閉弁とを有し、室内ユニット毎に冷房運転或いは暖房運転を行えるように構成した空気調和装置において、各室内ユニットの前記室内熱交換器の一端側に第１温度センサを設けるとともに、他端側に第２温度センサを設け、前記室内ユニットを暖房運転から冷房運転に切り換える際に、当該室内ユニット側の第１開閉弁、第２開閉弁、第３開閉弁及び冷媒減圧器を閉鎖する閉鎖手段と、この閉鎖手段により第１開閉弁、第２開閉弁、第３開閉弁及び冷媒減圧器を閉鎖してから室内熱交換器内の冷媒圧力が飽和圧力となるのに十分な長さの第１の所定時間が経過した場合、冷房運転を開始するに先立って、前記閉鎖手段により閉鎖された第３開閉弁を開放する開放手段と、前記第１の所定の時間が経過する前に、当該室内ユニットの第１温度センサにより検出された温度と第２温度センサにより検出された温度との差温が第１の所定値以下となった場合、前記第１の所定の時間を計時するタイマを強制的にタイムアップさせて、前記開放手段により前記第３開閉弁を開放させるタイムアップ手段とを備えたことを特徴とするものである。
【００１２】
この場合において、前記開放手段により第３開閉弁を開放する直前に当該室内ユニットの第１温度センサにより検出された温度と当該室内ユニットの第１温度センサにより検出された現在の温度との差温が、当該室内ユニットの室内熱交換器と前記低圧ガス管とが略均圧状態となる第２の所定値以上となった場合、前記閉鎖手段により閉鎖された第２開閉弁を開放し、冷房運転を開始する手段を備えたことを特徴とするものである。
【００１３】
この場合において、前記開放手段により第３開閉弁を開放する直前に当該室内ユニットの第１温度センサにより検出された温度と当該室内ユニットの第１温度センサにより検出された現在の温度との差温が、当該室内ユニットの室内熱交換器と前記低圧ガス管とが略均圧状態となる第２の所定値以上となる前に、室内熱交換器と低圧ガス管とが略均圧状態となるのに十分な長さの第２の所定の時間が経過した場合、前記冷房運転を開始する手段は前記閉鎖手段により閉鎖された第２開閉弁を開放し、冷房運転を開始してもよい。
【００１４】
また、圧縮機と室外熱交換器とを有する室外ユニットと、室内熱交換器を有する複数台の室内ユニットとを高圧ガス管、低圧ガス管及び液管を有するユニット間配管で接続し、各室内熱交換器の一端と前記高圧ガス管との間に配設される第１開閉弁と、各室内熱交換器の一端と前記低圧ガス管との間に配設される第２開閉弁と、各室内熱交換器の他端と前記液管との間に配設される冷媒減圧器とを有し、室内ユニット毎に冷房運転或いは暖房運転を行えるように構成した空気調和装置の制御方法において、前記室内ユニットを暖房運転から冷房運転に切り換える際に、当該室内ユニット側の第１開閉弁、第２開閉弁及び冷媒減圧器を閉鎖する閉鎖過程と、この閉鎖過程において第１開閉弁、第２開閉弁及び冷媒減圧器を閉鎖してから室内熱交換器内の冷媒圧力が飽和圧力となるのに十分な長さの第１の所定時間が経過した場合、冷房運転を開始するに先立って、前記閉鎖過程において閉鎖された第２開閉弁を開放する開放過程と、前記第１の所定の時間が経過する前に、当該室内ユニットの室内熱交換器の一端側の温度と他端側の温度との差温が第１の所定値以下となった場合、前記第１の所定の時間を計時するタイマを強制的にタイムアップさせて、前記開放過程に移行し、前記第２開閉弁を開放させるタイムアップ過程とを備えたことを特徴とするものである。
【００１５】
この場合において、前記開放過程において第２開閉弁を開放する直前の当該室内ユニットの室内熱交換器の一端側の温度と、当該室内ユニットの室内熱交換器の一端側の現在の温度との差温が、当該室内ユニットの室内熱交換器と前記低圧ガス管とが略均圧状態となる第２の所定値以上となった場合、冷房運転を開始する過程を備えたことを特徴とするものである。
【００１６】
この場合において、前記開放過程において第２開閉弁を開放する直前の当該室内ユニットの室内熱交換器の一端側の温度と、当該室内ユニットの室内熱交換器の一端側の現在の温度との差温が、当該室内ユニットの室内熱交換器と前記低圧ガス管とが略均圧状態となる第２の所定値以上となる前に、室内熱交換器と低圧ガス管とが略均圧状態となるのに十分な長さの第２の所定の時間が経過した場合、前記冷房運転を開始する過程に移行してもよい。
【００１７】
また、圧縮機と室外熱交換器とを有する室外ユニットと、室内熱交換器を有する複数台の室内ユニットとを高圧ガス管、低圧ガス管及び液管を有するユニット間配管で接続し、各室内熱交換器の一端と前記高圧ガス管とを接続する高圧ガス分岐管に配設される第１開閉弁と、各室内熱交換器の一端と前記低圧ガス管とを接続する低圧ガス分岐管に配設される第２開閉弁と、各室内熱交換器の他端と前記液管との間に配設される冷媒減圧器と、前記低圧ガス分岐管に並列接続され前記低圧ガス分岐管よりも流路抵抗の大きいバイパス管に配設される第３開閉弁とを有し、室内ユニット毎に冷房運転或いは暖房運転を行えるように構成した空気調和装置の制御方法において、前記室内ユニットを暖房運転から冷房運転に切り換える際に、当該室内ユニット側の第１開閉弁、第２開閉弁、第３開閉弁及び冷媒減圧器を閉鎖する閉鎖過程と、この閉鎖過程において第１開閉弁、第２開閉弁、第３開閉弁及び冷媒減圧器を閉鎖してから室内熱交換器内の冷媒圧力が飽和圧力となるのに十分な長さの第１の所定時間が経過した場合、冷房運転を開始するに先立って、前記閉鎖過程において閉鎖された第３開閉弁を開放する開放過程と、前記第１の所定の時間が経過する前に、当該室内ユニットの室内熱交換器の一端側の温度と他端側の温度との差温が第１の所定値以下となった場合、前記第１の所定の時間を計時するタイマを強制的にタイムアップさせて、前記開放過程に移行し、前記第３開閉弁を開放させるタイムアップ過程と、を備えたことを特徴とするものである。
【００１８】
この場合において、前記開放過程において第３開閉弁を開放する直前の当該室内ユニットの室内熱交換器の一端側の温度と、当該室内ユニットの室内熱交換器の一端側の現在の温度との差温が、当該室内ユニットの室内熱交換器と前記低圧ガス管とが略均圧状態となる第２の所定値以上となった場合、前記閉鎖過程において閉鎖された第２開閉弁を開放し、冷房運転を開始する過程を備えてもよい。
【００１９】
この場合において、前記開放過程において第３開閉弁を開放する直前の当該室内ユニットの室内熱交換器の一端側の温度と、当該室内ユニットの室内熱交換器の一端側の現在の温度との差温が、当該室内ユニットの室内熱交換器と前記低圧ガス管とが略均圧状態となる第２の所定値以上となる前に、室内熱交換器と低圧ガス管とが略均圧状態となるのに十分な長さの第２の所定の時間が経過した場合、前記冷房運転を開始する過程に移行し、前記閉鎖過程において閉鎖された第２開閉弁を開放し冷房運転を開始してもよい。
【００２０】
【発明の実施の形態】
以下、本発明の実施の形態を、図面に基づき説明する。
【００２１】
図１は、本発明に係る空気調和装置の実施の形態を示す冷媒回路図等である。この空気調和装置５０は、室外ユニット１と複数台（図１では例えば、２台）の室内ユニット２ａ，２ｂとを有して構成される。
【００２２】
室外ユニット１は、圧縮機３及び室外熱交換器４を備えている。室外熱交換器４には、室外ファン５が隣接して配置されている。圧縮機３は、例えば、不図示のガスエンジンにより駆動される。室外熱交換器４は、複数台（例えば、２台）の室外熱交換器４ａ，４ｂから成り、室外熱交換器４ａ，４ｂは、並列接続されている。例えば、室外熱交換器４ａと室外熱交換器４ｂとは、熱交換容量（熱交換能力）が異なる。
【００２３】
また、室内ユニット２ａ，２ｂは、室内熱交換器６ａ，６ｂ及び冷媒減圧器としての室内電子膨張弁１８ａ，１８ｂを備えている。室内熱交換器６ａ，６ｂのそれぞれには、室内ファン９ａ，９ｂのそれぞれが隣接して配置される。
【００２４】
そして、これらの室外ユニット１と室内ユニット２ａ，２ｂとが、高圧ガス管１１、低圧ガス管１２及び液管１３を有するユニット間配管１０により接続されて、空気調和装置５０は、室内ユニット２ａ，２ｂを同時に冷房運転もしくは暖房運転可能とし、または、これらの冷房運転と暖房運転とを混在して実施可能とする。つまり、室内ユニット２ａ，２ｂ毎に冷房運転或いは暖房運転を行えるように構成されている。
【００２５】
室外ユニット１では、室外熱交換器４の一端が、圧縮機３の冷媒吐出管７と冷媒吸込管８とに、択一に分岐して接続されている。
【００２６】
具体的には、室外熱交換器４ａの一端が、圧縮機３の冷媒吐出管７に切換弁２１ａを介して接続されるとともに、圧縮機３の冷媒吸込管８に切換弁２２ａを介して接続される。また、室外熱交換器４ｂの一端が、圧縮機３の冷媒吐出管７に切換弁２１ｂを介して接続されるとともに、圧縮機３の冷媒吸込管８に切換弁２２ｂを介して接続される。
【００２７】
上記ユニット間配管１０の高圧ガス管１１は冷媒吐出管７に接続される。また、低圧ガス管１２は、冷媒吸込管８に接続される。また、液管１３は、レシーバタンク２６および補助冷媒減圧器としての室外電子膨張弁２７ａ，２７ｂのそれぞれを介して室外熱交換器４ａ，４ｂのそれぞれの他端に接続される。
【００２８】
冷媒吸込管８には、アキュムレータ２４が配設され、冷媒吐出管７には、オイルセパレータ２５が配設されている。また、冷媒吐出管７と冷媒吸込管８とをバイパスする高低圧バイパス弁２３が設けられている。
【００２９】
上記室内ユニット２ａ，２ｂのそれぞれの室内熱交換器６ａ，６ｂは、それらの他端が、室内電子膨張弁１８ａを配設した液分岐管１９ａ、室内電子膨張弁１８ｂを配設した液分岐管１９ｂを介して液管１３にそれぞれ接続される。
【００３０】
また、上記室内ユニット２ａの室内熱交換器６ａは、その一端が、高圧ガス分岐管１４ａを介して高圧ガス管１１に接続されるとともに、低圧ガス分岐管１５ａを介して低圧ガス管１２に接続される。また、室内ユニット２ｂの室内熱交換器６ｂは、その一端が、高圧ガス分岐管１４ｂを介して高圧ガス管１１に接続されるとともに、低圧ガス分岐管１５ｂを介して低圧ガス管１２に接続される。
【００３１】
高圧ガス分岐管１４ａ，１４ｂのそれぞれに、第１開閉弁（第１電磁開閉弁）１６ａ，１６ｂが配設される。また、低圧ガス分岐管１５ａ，１５ｂのそれぞれに、第２開閉弁（第２電磁開閉弁）１７ａ，１７ｂが配設される。
【００３２】
低圧ガス分岐管１５ａ，１５ｂには、第２開閉弁１７ａ，１７ｂをバイパスする第１バイパス管２８ａ，２８ｂ及び第２バイパス管２９ａ，２９ｂが並列接続される。
【００３３】
第１バイパス管２８ａ，２８ｂのそれぞれに、第３開閉弁（第３電磁開閉弁）３０ａ，３０ｂがそれぞれ配設される。また、第２バイパス管２９ａ，２９ｂのそれぞれに、第４開閉弁（第４電磁開閉弁）３１ａ，３１ｂがそれぞれ配設される。
【００３４】
第１バイパス管２８ａ，２８ｂ及び第２バイパス管２９ａ，２９ｂは、低圧ガス分岐管１５ａ，１５ｂよりも口径を小さくすることで、低圧ガス分岐管１５ａ，１５ｂよりも冷媒の流路抵抗を大きくしている。
【００３５】
第１開閉弁１６ａ，１６ｂ、第２開閉弁１７ａ，１７ｂ、第３開閉弁３０ａ，３０ｂ、第４開閉弁３１ａ，３１ｂのそれぞれは、電磁弁ユニット２０ａ，２０ｂのそれぞれに格納されている。
【００３６】
各室内ユニット２ａ，２ｂの室内熱交換器６ａ，６ｂの一端側（蒸発器として作用するときの冷媒出口側）には、冷媒の温度を検出するための第１温度センサ４３ａ，４３ｂが設けられている。また、各室内ユニット２ａ，２ｂの室内熱交換器６ａ，６ｂの他端側（蒸発器として作用するときの冷媒入口側）には、冷媒の温度を検出するための第２温度センサ４４ａ，４４ｂが設けられている。つまり、第１温度センサ４３ａ，４３ｂは、室内熱交換器６ａ，６ｂのガス冷媒の温度を検出し、第２温度センサ４４ａ，４４ｂは、液冷媒の温度を検出していることになる。
【００３７】
室外ユニット１には、室外ユニット１を制御する室外制御装置４１が備えられている。また、各室内ユニット２ａ，２ｂには、それぞれの室内ユニット２ａ，２ｂを制御する室内制御装置４２ａ，４２ｂが備えられている。そして、室内制御装置４２ａ，４２ｂは、室外制御装置４１に通信線で接続されている。
【００３８】
各室内制御装置４２ａ，４２ｂのそれぞれは、第１温度センサ４３ａ，４３ｂの検出した温度及び第２温度センサ４４ａ，４４ｂの検出した温度を取得する。そして、これら検出結果を、室外制御装置４１に送信している。また、各室内制御装置４２ａ，４２ｂのそれぞれは、室外制御装置４１によって送信された指令に基づいて室内電子膨張弁１８ａ，１８ｂの弁開度、電磁弁ユニット２０ａ，２０ｂ（つまり、第１開閉弁１６ａ，１６ｂ、第２開閉弁１７ａ，１７ｂ、第３開閉弁３０ａ，３０ｂ及び第４開閉弁３１ａ，３１ｂ）の弁開閉及び室内ファン９ａ，９ｂの回転数等を制御する。
【００３９】
室外制御装置４１は、各室内制御装置４２ａ，４２ｂに室内電子膨張弁１８ａ，１８ｂ、電磁弁ユニット２０ａ，２０ｂ及び室内ファン９ａ，９ｂ等を制御させるための指令を送信する。また、室外制御装置４１は、室外電子膨張弁２７ａ，２７ｂの弁開度、切換弁２１ａ，２２ａ，２１ｂ，２２ｂの弁開閉、室外ファン５の回転数、及び高低圧バイパス弁２３の開度等を制御する。
【００４０】
これら室外制御装置４１及び室内制御装置４２ａ，４２ｂによって空気調和装置５０全体の制御が行われる。
【００４１】
室外電子膨張弁２７ａ，２７ｂおよび室内電子膨張弁１８ａ，１８ｂは、例えば不図示のステッピングモータによって弁開度が調整される。そして、例えば、ステッピングモータへ入力されるパルス（ステップ）が、例えば、２０ステップのときが全閉、４８０ステップのときが全開となるように設定されている。
【００４２】
室内制御装置４２ａ，４２ｂは、不図示のリモートコントローラにより設定された運転モード（冷房運転或いは暖房運転）に応じて第１開閉弁１６ａ，１６ｂ、第２開閉弁１７ａ，１７ｂ、第３開閉弁３０ａ，３０ｂ及び第４開閉弁３１ａ，３１ｂの開閉制御を行う。そして、室内制御装置４２ａ，４２ｂは、室内ユニット２ａ，２ｂのリモートコントローラの設定情報を含む信号を室外制御装置４１に送信する。
【００４３】
次に運転動作を説明する。
【００４４】
（Ａ）全室内ユニット２ａ，２ｂを同時に冷房運転する場合は、高圧ガス管１１が休止状態におかれる。
【００４５】
この場合、室外熱交換器４ａ，４ｂの一方の切換弁２１ａ，２１ｂを開くとともに他方の切換弁２２ａ，２２ｂを閉じ、且つ電磁弁ユニット２０ａ，２０ｂの第１開閉弁１６ａ，１６ｂを閉じるとともに、第２開閉弁１７ａ，１７ｂと第３開閉弁３０ａ，３０ｂと第４開閉弁３１ａ，３１ｂとを開く。
【００４６】
これにより、圧縮機３から吐出された冷媒は、冷媒吐出管７、オイルセパレータ２５、切換弁２１ａ，２１ｂ、室外熱交換器４ａ，４ｂへと順次流れ、室外熱交換器４ａ，４ｂで凝縮液化する。凝縮液化した冷媒は、室外電子膨張弁２７ａ，２７ｂ及びレシーバタンク２６を通過し、液管１３と液分岐管１９ａ，１９ｂを経て各室ユニット２ａ，２ｂの室内電子膨張弁１８ａ，１８ｂに分配され、ここで減圧される。
【００４７】
しかる後、室内電子膨張弁１８ａ，１８ｂで減圧された冷媒は、各室内熱交換器６ａ，６ｂで蒸発気化した後、それぞれ第２開閉弁１７ａ，１７ｂと第３開閉弁３０ａ，３０ｂと第４開閉弁３１ａ，３１ｂとを並流した後、低圧ガス管１２、冷媒吸込管８、アキュムレータ２４を順次経て圧縮機３に吸入される。
【００４８】
このように、蒸発器として作用する各室内熱交換器６ａ，６ｂで全室内ユニット２ａ，２ｂが同時に冷房運転される。
【００４９】
（Ｂ）全室内ユニット２ａ，２ｂを同時に暖房運転する場合は、低圧ガス管１２が休止状態におかれる。
【００５０】
この場合、室外熱交換器４ａ，４ｂの一方の切換弁２１ａ，２１ｂを閉じるとともに他方の切換弁２２ａ，２２ｂを開き、且つ電磁弁ユニット２０ａ，２０ｂの第１開閉弁１６ａ，１６ｂを開くとともに、第２開閉弁１７ａ，１７ｂと第３開閉弁３０ａ，３０ｂと第４開閉弁３１ａ，３１ｂとを閉じる。
【００５１】
これにより、圧縮機３から吐出された冷媒は、冷媒吐出管７、オイルセパレータ２５、高圧ガス管１１を順次経て高圧ガス分岐管１４ａ，１４ｂに分配された後、第１開閉弁１６ａ，１６ｂ、室内熱交換器６ａ，６ｂへと流れ、ここでそれぞれ凝縮液化する。
【００５２】
凝縮液化した冷媒は、各室内電子膨張弁１８ａ，１８ｂで減圧され、液分岐管１９ａ，１９ｂを経て液管１３で合流される。
【００５３】
しかる後、液管１３の液冷媒は、レシーバタンク２６及び室外電子膨張弁２７ａ，２７ｂを通過し、室外熱交換器４ａ，４ｂで蒸発気化した後、切換弁２２ａ，２２ｂ、冷媒吸込管８、アキュムレータ２４を順次経て圧縮機３に吸入される。このように凝縮器として作用する各室内熱交換器６ａ，６ｂで、全室内ユニット２ａ，２ｂが同時に暖房運転される。
【００５４】
（Ｃ）次に、例えば室内ユニット２ａを冷房運転し、室内ユニット２ｂを暖房運転する場合は、全ての冷媒管１１，１２，１３が使用される。まず、室内ユニット２ａ側の冷房負荷が室内ユニット２ｂ側の暖房負荷よりも大きい場合について説明する。
【００５５】
この場合、室外熱交換器４ａ，４ｂの一方の切換弁２１ａ，２１ｂを開くとともに他方の切換弁２２ａ，２２ｂを閉じ、且つ、冷房運転する室内ユニット２ａの電磁弁ユニット２０ａにおける第１開閉弁１６ａを閉じるとともに、第２開閉弁１７ａと第３開閉弁３０ａと第４開閉弁３１ａとを開き、且つ暖房運転する室内ユニット２ｂの電磁弁ユニット２０ｂにおける第１開閉弁１６ｂを開くとともに、第２開閉弁１７ｂと第３開閉弁３０ｂと第４開閉弁３１ｂとを閉じる。
【００５６】
すると、圧縮機３から吐出され、冷媒吐出管７及びオイルセパレータ２５を通過した冷媒の一部が、切換弁２１ａ，２１ｂを経て室外熱交換器４ａ，４ｂに流れるとともに、残りの冷媒が高圧ガス管１１を経て暖房運転する室内ユニット２ｂの電磁弁ユニット２０ｂにおける第１開閉弁１６ｂ、室内熱交換器６ｂへと流れる。これによって、室内熱交換器６ｂ及び室外熱交換器４ａ，４ｂで凝縮液化される。
【００５７】
そして、これら室内熱交換器６ｂ及び室外熱交換器４ａ，４ｂで凝縮液化された冷媒は、液管１３を経て室内ユニット２ａの室内電子膨張弁１８ａで減圧された後、室内熱交換器６ａで蒸発気化される。しかる後、冷媒は、第２開閉弁１７ａと第３開閉弁３０ａと第４開閉弁３１ａを並流して低圧ガス管１２で合流され、冷媒吸込管８、アキュムレータ２４を順次経て圧縮機３に吸入される。このように、凝縮器として作用する室内熱交換器６ｂで室内ユニット２ｂが暖房運転され、蒸発器として作用する室内熱交換器６ａで室内ユニット２ａが冷房運転される。
【００５８】
次に、室内ユニット２ｂ側の暖房負荷が室内ユニット２ａ側の冷房負荷よりも大きい場合について説明する。
【００５９】
この場合には、室外熱交換器４ａ，４ｂの一方の切換弁２１ａ，２１ｂを閉じるとともに他方の切換弁２２ａ，２２ｂを開き、且つ冷房運転する室内ユニット２ａの電磁弁ユニット２０ａにおける第１開閉弁１６ａを閉じるとともに、第２開閉弁１７ａと第３開閉弁３０ａと第４開閉弁３１ａとを開き、且つ暖房運転する室内ユニット２ｂの電磁弁ユニット２０ｂにおける第１開閉弁１６ｂを開くとともに、第２開閉弁１７ｂと第３開閉弁３０ｂと第４開閉弁３１ｂとを閉じる。
【００６０】
すると、圧縮機３から吐出された冷媒は、冷媒吐出管７、高圧ガス管１１を順次経て第１開閉弁１６ｂを通過して室内熱交換器６ｂで凝縮液化される。
【００６１】
そして、この液化された冷媒は、全開された室内電子膨張弁１８ｂを経て液管１３に流れる。この液管中の液冷媒の一部が、室内電子膨張弁１８ａで減圧された後に室内熱交換器６ｂで、且つ、残りの液冷媒が室外電子膨張弁２７ａ，２７ｂで減圧された後に室外熱交換器４ａ，４ｂでそれぞれ蒸発気化され、冷媒吸込管８、アキュムレータ２４を順次経て圧縮機３に吸入される。このように、凝縮器として作用する室内熱交換器６ｂで室内ユニット２ｂが暖房運転され、蒸発器として作用する室内熱交換器６ａで室内ユニット２ａが冷房運転される。
【００６２】
以上の如く、冷房運転する室内ユニット２ａ，２ｂの冷房負荷が、暖房運転する室内ユニット２ａ，２ｂの暖房負荷よりも大きいときは、室外熱交換器４ａ，４ｂを凝縮器として作用させる。一方、冷房する室内ユニット２ａ，２ｂの冷房負荷が、暖房する室内ユニット２ａ，２ｂの暖房負荷よりも少ないときは、室外熱交換器４ａ，４ｂを蒸発器として作用させる。これらにより、任意の室内ユニット２ａ，２ｂを自由に冷暖房することができる。
【００６３】
上記（Ａ）〜（Ｃ）に示した運転状態において、室内ユニット２ａ，２ｂの冷房負荷と暖房負荷との差が所定値よりも小さい場合、室外制御装置４１は、室外熱交換器４ａ或いは４ｂを休止させる制御を行う。室外熱交換器４ａを休止させる場合、室外制御装置４１は、室外電子膨張弁２７ａを全閉に制御するとともに、切換弁２１ａ及び２２ａを閉弁する制御を行う。室外熱交換器４ｂを休止させる場合、室外制御装置４１は、室外電子膨張弁２７ｂを全閉に制御するとともに、切換弁２１ｂ及び２２ｂを閉弁する制御を行う。
【００６４】
更に、上記（Ｃ）に示した運転状態において、室内ユニット２ａ，２ｂの冷房負荷と暖房負荷とが同じ場合、室外制御装置４１は、室外熱交換器４ａ及び４ｂを休止させるべく、室外電子膨張弁２７ａ及び２７ｂを全閉に制御するとともに、切換弁２１、２２ａ、２１ｂ及び２２ｂを閉弁する制御を行う。
【００６５】
本実施の形態では、上記の運転動作中に室内ユニット（例えば、２ａ）が暖房運転から冷房運転に切り換わる場合、例えば、不図示のリモートコントローラにより室内ユニット２ａが暖房運転から冷房運転に切り換えられた場合、室外制御装置４１及び室内制御装置４２ａが室内ユニット２ａから生じる冷媒音を防止する制御を行うものである。尚、室内ユニット２ｂにおいても室内ユニット２ａと同様に動作するので、室内ユニット２ｂの動作については説明を省略する。
【００６６】
以下、室外制御装置４１及び室内制御装置４２ａの制御動作について、図２に示すフローチャートを参照しながら説明する。
【００６７】
まず、室外制御装置４１は、室内ユニット２ａ，２ｂの運転モードを判別し（ステップＳ１）、例えば、室内ユニット２ａが暖房運転から冷房運転に切り換わる場合、室内制御装置４２ａに室内ユニット２ａの電磁弁ユニット２０ａの第１開閉弁１６ａ、第２開閉弁１７ａ、第３開閉弁３０ａ、及び第４開閉弁３１ａを閉鎖（閉弁）するように指令を送信し、この指令を受信した室内制御装置４２ａは、電磁弁ユニット２０ａの第１開閉弁１６ａ、第２開閉弁１７ａ、第３開閉弁３０ａ、及び第４開閉弁３１ａを閉弁制御する（ステップＳ２）。
【００６８】
更に、室外制御装置４１は、室内制御装置４２ａに室内電子膨張弁１８ａを閉鎖（全閉）する指令を送信し、この指令を受信した室内制御装置４２ａは、室内電子膨張弁１８ａを全閉に制御する（ステップＳ３）。具体的には、室外制御装置４１は、室内制御装置４２ａに室内電子膨張弁１８ａの不図示のステッピングモータを２０ステップに設定するように指令を送信し、この指令を受信した室内制御装置４２ａは、室内電子膨張弁１８ａの不図示のステッピングモータを２０ステップに設定する制御を行う。
【００６９】
ステップＳ２及びＳ３の動作を行う前、つまり、電磁弁ユニット２０ａの第１開閉弁１６ａ、第２開閉弁１７ａ、第３開閉弁３０ａ及び第４開閉弁３１ａ並びに室内電子膨張弁１８ａを閉鎖する前は、室内ユニット２ａにおいて暖房運転が行われているので、室内熱交換器６ａの一端側の冷媒圧力と他端側の冷媒圧力とに圧力差が生じていることになる。このとき、室内熱交換器６ａの一端側の圧力は、室内熱交換器６ａの他端側の圧力よりも高くなっいる。そして、ステップＳ２及びＳ３により電磁弁ユニット２０ａの第１開閉弁１６ａ、第２開閉弁１７ａ、第３開閉弁３０ａ及び第４開閉弁３１ａ並びに室内電子膨張弁１８ａを閉鎖した場合、室内熱交換器６ａ内は、平衡状態（飽和圧力）となるように、圧力差（温度差）が徐々に小さくなる。更に、室内熱交換器６ａ内の冷媒は、放熱作用により圧力（温度）が徐々に小さくなる。
【００７０】
従って、室外制御装置４１は、不図示のタイマにより電磁弁ユニット２０ａの第１開閉弁１６ａ、第２開閉弁１７ａ、第３開閉弁３０ａ及び第４開閉弁３１ａ並びに室内電子膨張弁１８ａを閉弁してから計時を開始する（ステップＳ４）。このとき、タイマには、室内熱交換器６ａ内の冷媒圧力が飽和圧力となるのに十分な長さの第１の所定時間Ｔ１（例えば、１２０［ｓｅｃ］）まで計時するように設定されている。
【００７１】
次に、室外制御装置４１は、第１の所定時間Ｔ１が経過したか否かを判別する（ステップＳ５）。
【００７２】
第１の所定時間Ｔ１が経過していない場合（ステップＳ５；Ｎｏ）、室外制御装置４１は、第１温度センサ４３ａにより検出された温度と、第２温度センサ４４ａにより検出された温度との差温Ｔｄｎを演算する（ステップＳ６）。つまり、室外制御装置４１は、室内熱交換器６ａの一端側の温度（ガス冷媒温度）と、室内熱交換器６ａの他端側の温度（液冷媒温度）との差温Ｔｄｎを演算している。
【００７３】
次に、室外制御装置４１は、この差温Ｔｄｎが、室内熱交換器６ａ内の冷媒圧力が飽和圧力の近傍となる第１の所定値（例えば、２０［Ｋ］）以下であるか否かを判別する（ステップＳ７；第１判別手段）。
【００７４】
差温Ｔｄｎが第１の所定値以下である場合（ステップＳ７；Ｙｅｓ）、室外制御装置４１は、不図示のタイマを強制的にタイムアップさせ（ステップＳ８）、ステップＳ５の判別に移行する。
【００７５】
つまり、差温Ｔｄｎが第１の所定値以下である場合は、室内熱交換器６ａ内の冷媒圧力が飽和圧力の近傍であるので、第１の所定時間Ｔ１が経過するのを待つ必要がない。
【００７６】
また、差温Ｔｄｎが第１の所定値以下ではない場合、つまり差温Ｔｄｎが第１の所定値よりも大きい場合（ステップＳ７；Ｎｏ）、ステップＳ５の判別に移行する。
【００７７】
ステップＳ５において、差温Ｔｄｎが第１の所定値以下となった場合、或いは第１開閉弁１６ａと、第２開閉弁１７ａと、第３開閉弁３０ａと、第４開閉弁３１ａと、室内電子膨張弁１８ａとを閉弁してから第１の所定時間Ｔ１が経過した場合、言い換えれば、不図示のタイマの計時がタイムアップした場合（ステップＳ５；Ｙｅｓ）、室外制御装置４１は、第１温度センサ４３ａにより検出された温度（室内熱交換器６ａのガス冷媒温度）Ｔｇ１を記憶する（ステップＳ９；記憶手段）。
【００７８】
ここで、仮に、第１の所定時間Ｔ１（例えば、１２０［ｓｅｃ］）が経過して、差温Ｔｄｎが第１の所定値（例えば、２０［Ｋ］）よりも大きい場合であっても、室内熱交換器６ａ内の冷媒は、電磁弁ユニット２０ａの第２開閉弁１７ａ、第３開閉弁３０ａ或いは第４開閉弁３１ａの開放時に冷媒音が発生しない程度に十分に冷却（減圧）されている。
【００７９】
また、温度センサ４３ａ，４４ａの異常により正しい値を検出できないような状態になっても、第１の所定時間Ｔ１（例えば、１２０［ｓｅｃ］）が経過すれば、次のステップＳ９に移行することができるので、制御の安定性が向上する。
【００８０】
次に、電磁弁ユニット２０ａの第３制御弁３０ａのみを開放（開弁）するように室内制御装置４２ａに指令を送信し、この指令を受信した室内制御装置４２ａは、第３制御弁３０ａを開弁制御する（ステップＳ１０）。
【００８１】
つまり、このステップＳ１０では、室内熱交換器６ａ内の冷媒圧力を低圧ガス管１２内の冷媒圧力に近づけるために第３制御弁３０ａを開弁制御している。このステップＳ１０において、第３制御弁３０ａを開弁制御するものとしたが、第２開閉弁１７ａを開弁制御してもよい。これによっても、室内熱交換器６ａ内の冷媒圧力を低圧ガス管１２内の冷媒圧力に近づけることが可能である。
【００８２】
特に、ステップＳ１０のように第３制御弁３０ａが開弁されると、室内熱交換器６ａ内の冷媒は、低圧ガス分岐管１５ａよりも冷媒の流路抵抗の大きい第１バイパス管２８ａを通じて低圧ガス管１２側に流れることになるので、より冷媒音の発生を抑制することができる。
【００８３】
次に、室外制御装置４１は、不図示のタイマにより電磁弁ユニット２０ａの第３制御弁３０ａを閉弁してから計時を開始する（ステップＳ１１）。このとき、タイマには、室内熱交換器６ａ内の冷媒圧力が低下して室内熱交換器６ａと低圧ガス管１２とが略均圧状態となるのに十分な長さの第２の所定時間Ｔ２（例えば、２４０［ｓｅｃ］）まで計時するように設定されている。
【００８４】
次に、室外制御装置４１は、第２の所定時間Ｔ２が経過したか否かを判別する（ステップＳ１２）。
【００８５】
第２の所定時間Ｔ２が経過していない場合（ステップＳ１２；Ｎｏ）、室外制御装置４１は、第３制御弁３０ａを開く直前に第１温度センサ４３ａにより検出された温度（室内熱交換器６ａのガス冷媒温度）Ｔｇ１（即ち、記憶された温度Ｔｇ１）と、第１温度センサ４３ａにより検出された現在の温度（現在の室内熱交換器６ａのガス冷媒温度）との差温Ｔｄｇｎを演算する（ステップＳ１３）。具体的には、室外制御装置４１は、記憶された温度Ｔｇ１と現在の室内熱交換器６ａのガス冷媒温度との差温の絶対値Ｔｄｇｎを演算している。
【００８６】
ここで、室内熱交換器６ａの一端側の温度（ガス冷媒温度）は、第３開閉弁３０ａが開弁されているので、経過時間とともに徐々に低下していき、差温Ｔｄｇｎは、徐々に大きくなっていく。
【００８７】
次に、室外制御装置４１は、この差温Ｔｄｇｎが、室内熱交換器６ａと低圧ガス管１２とが略均圧状態となる第２の所定値（例えば、１５［Ｋ］）以上であるか否かを判別する（ステップＳ１４；第２判別手段）。
【００８８】
差温Ｔｄｇｎが第２の所定値以上である場合（ステップＳ１４；Ｙｅｓ）、室外制御装置４１は、不図示のタイマを強制的にタイムアップさせ（ステップＳ１５）、ステップＳ１２の判別に移行する。
【００８９】
つまり、差温Ｔｄｇｎが第２の所定値以上である場合は、室内熱交換器６ａと低圧ガス管１２とが略均圧しているで、第２の所定時間Ｔ２が経過するのを待つ必要がない。
【００９０】
差温Ｔｄｇｎが第２の所定値以上ではない場合、つまり差温Ｔｄｇｎが第２の所定値よりも小さい場合（ステップＳ１４；Ｎｏ）、ステップＳ１２の判別に移行する。
【００９１】
ステップＳ１２において、差温Ｔｄｇｎが第２の所定値以上となった場合、或いは第３開閉弁３０ａを開弁してから第２の所定時間Ｔ２が経過した場合、言い換えれば、不図示のタイマの計時がタイムアップした場合（ステップＳ１２；Ｙｅｓ）、室外制御装置４１は、第２開閉弁１７ａを開き、冷房運転を開始するように室内制御装置４２ａに指令を送信し、この指令を受信した室内制御装置４２ａは第２開閉弁１７ａを開き、冷房運転を開始する制御を行う。この冷房運転を開始する制御を行うとき、室内電子膨張弁１８ａは、冷房負荷に応じた弁開度となるように調整される。つまり、通常の冷房運転が開始される。
【００９２】
ここで、仮に、第２の所定時間Ｔ２（例えば、２４０［ｓｅｃ］）が経過して、差温Ｔｄｇｎが第２の所定値（例えば、１５［Ｋ］）よりも小さい場合であっても、室内熱交換器６ａ内の冷媒圧力は、低圧ガス管１２内の冷媒圧力に十分近づけられているので、冷房運転を開始しても冷媒音が発生することはない。
【００９３】
また、温度センサ４３ａ，４４ａの異常により正しい値を検出できないような状態になっても、第２の所定時間Ｔ２（例えば、２４０［ｓｅｃ］）が経過すれば、次のステップＳ１６に移行することができるので、制御の安定性が向上する。
【００９４】
以上の動作によって、冷房運転から暖房運転に切り換わる際に、効率的に室内ユニット２ａ（室内熱交換器６ａや電磁弁ユニット２０ａ付近）からの冷媒音の発生を抑制することができる。
【００９５】
以上、本実施の形態によれば、いずれかの室内ユニットを暖房運転から冷房運転に切り換える際に、当該室内ユニット側の電磁弁ユニットの第１〜第４開閉弁及び室内電子膨張弁を閉鎖する制御を行い、冷房運転を開始するに先立って、差温Ｔｄｎが第１の所定値以下であるか否かを判別することから、正確に室内熱交換器６ａ内の冷媒圧力が飽和圧力になったか否かを判別することができるので、室内ユニットの冷媒音を抑制する確実性が向上する。
【００９６】
そして、差温Ｔｄｎが第１の所定値以下である場合、第３開閉弁のみを開放するようにしたことから、従来のように弁を閉じてから一律に予め設定した所定時間（例えば、６０［ｓｅｃ］）経過するのを待つ場合と比較して、短時間で差温Ｔｄｎが第１の所定値以下となるときに制御動作の時間を短縮することができ、より効率よく冷媒音の発生を抑制することができる。更に、制御動作の時間を短縮することができるので、暖房運転から冷房運転への切換時間を短縮することができ、空調性が向上する。
【００９７】
また、本実施の形態によれば、差温Ｔｄｇｎが、室内熱交換器６ａと低圧ガス管１２とが略均圧状態となる第２の所定値以上であるか否かを判別することから、正確に室内熱交換器６ａ内の冷媒圧力が低圧ガス管１２内の冷媒圧力に近づいている否かを判別することができるので、室内ユニットの冷媒音を抑制する確実性が向上する。
【００９８】
そして、差温Ｔｄｇｎが第２の所定値以上である場合、第２開閉弁１７ａを開放し、通常の冷房運転を開始するようにしたことから、従来のように弁を閉じてから一律に予め設定した所定時間（例えば、１２０［ｓｅｃ］）経過するのを待つ場合と比較して、短時間で差温Ｔｄｇｎが第２の所定値以上となるときに制御動作の時間を短縮することができ、より効率よく冷媒音の発生を抑制することができる。更に、制御動作の時間を短縮することができるので、暖房運転から冷房運転への切換時間を短縮することができ、空調性が向上する。
【００９９】
以上、本発明を上記実施の形態に基づいて説明したが、本発明はこれに限定されるものではない。
【０１００】
例えば、上記実施の形態では、低圧ガス分岐管１５ａ，１５ｂには、第２開閉弁１７ａ，１７ｂをバイパスする第４開閉弁３１ａ，３１ｂを配設した第２バイパス管２９ａ，２９ｂが並列接続される場合について説明したが、第４開閉弁３１ａ，３１ｂ及び第２バイパス管２９ａ，２９ｂは、省略可能である。
【０１０１】
また、上記実施の形態では、低圧ガス分岐管１５ａ，１５ｂには、第２開閉弁１７ａ，１７ｂをバイパスする第３開閉弁３０ａ，３０ｂを配設した第１バイパス管２８ａ，２８ｂが並列接続される場合について説明したが、第３開閉弁３０ａ，３０ｂ及び第１バイパス管２８ａ，２８ｂは、省略可能である。この場合、図２に示すステップＳ１０では、第２開閉弁のみが開弁制御されることになる。これによっても、上記実施の形態と同様に、効率よく冷媒音の発生を抑制することができるという効果を奏する。
【０１０２】
また、上記実施の形態では、ステップＳ１０において第３開閉弁３０ａを開放する場合について説明したが、第２開閉弁を配設した低圧ガス分岐管に並列接続され低圧ガス分岐管よりも流路抵抗の大きいバイパス管に配設される開閉弁であればよく、例えば、第４開閉弁３１ａを開放する場合でもよい。
【０１０３】
【発明の効果】
本発明によれば、効率よく冷媒音の発生を抑制することができる。
【図面の簡単な説明】
【図１】本発明による空気調和装置の一実施の形態を示す冷媒回路図等である。
【図２】暖房運転から冷房運転に切り換わる際の制御動作を示すフローチャートである。
【符号の説明】
１室外ユニット
２ａ，２ｂ室内ユニット
３圧縮機
４室外熱交換器
１０ユニット間配管
１１高圧ガス管
１２低圧ガス管
１３液管
１４ａ，１４ｂ高圧ガス分岐管
１５ａ，１５ｂ低圧ガス分岐管
１６ａ，１６ｂ第１開閉弁
１７ａ，１７ｂ第２開閉弁
１８ａ，１８ｂ室内電子膨張弁（冷媒減圧器）
１９ａ，１９ｂ液分岐管
２０ａ，２０ｂ電磁弁ユニット
２８ａ，２８ｂ第１バイパス管（バイパス管）
３０ａ，３０ｂ第３開閉弁
４１室外制御装置（閉鎖手段、開放手段）
４２ａ，４２ｂ室内制御装置（閉鎖手段、開放手段）
４３ａ，４３ｂ第１温度センサ
４４ａ，４４ｂ第２温度センサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioner in which an outdoor unit and an indoor unit are connected by a unit pipe having a high pressure gas pipe, a low pressure gas pipe, and a liquid pipe, and a control method for the air conditioner.
[0002]
[Prior art]
In general, an outdoor unit having a compressor and an outdoor heat exchanger and a plurality of indoor units having an indoor heat exchanger are connected by an inter-unit pipe having a high pressure gas pipe, a low pressure gas pipe, and a liquid pipe. A first on-off valve disposed in a high-pressure gas branch pipe connecting one end of the heat exchanger and the high-pressure gas pipe, and a low-pressure gas branch pipe connecting one end of each indoor heat exchanger and the low-pressure gas pipe The second open / close valve, the refrigerant pressure reducer disposed between the other end of each indoor heat exchanger and the liquid pipe, and a flow resistance higher than that of the low pressure gas branch pipe connected in parallel to the low pressure gas branch pipe. There is known an air conditioner having a third on-off valve disposed in a large bypass pipe and configured to perform cooling operation or heating operation for each indoor unit (see, for example, Patent Document 1).
[0003]
In such an air conditioner, when the indoor unit switches from the heating operation to the cooling operation, the indoor heat exchanger that has acted as a condenser during the heating operation by the opening / closing operation of the on-off valve on the indoor unit side becomes the cooling operation. Since switching to the evaporator is performed at the time of switching, a sudden pressure change occurs in the indoor heat exchanger. Due to this pressure change, significant refrigerant noise may occur near the indoor heat exchanger or the on-off valve.
[0004]
Therefore, conventionally, when the indoor unit is switched from the heating operation to the cooling operation, the first on-off valve, the second on-off valve, the third on the indoor unit side, in order to bring the refrigerant pressure in the indoor heat exchanger closer to the saturation pressure. The on-off valve and the refrigerant pressure reducer are closed for a certain time (for example, 60 [sec]), and then only the third on-off valve is kept for a certain time so that the pressure in the indoor heat exchanger approaches the pressure on the low-pressure gas pipe side. (For example, 180 [sec]), and then the second on-off valve is opened to perform a normal cooling operation, thereby avoiding refrigerant noise.
[0005]
[Patent Document 1]
Japanese Patent No. 2804527
[0006]
[Problems to be solved by the invention]
However, in the above air conditioner, since the on-off valve is operated for a preset time, even if the pressure in the indoor heat exchanger has already dropped to a pressure that can avoid the refrigerant noise, There is a problem that it is not efficient because it is necessary to wait for a certain period of time to pass to the cooling operation.
[0007]
An object of the present invention is to provide an air conditioner and a control method for the air conditioner that can efficiently suppress the generation of refrigerant noise.
[0008]
[Means for Solving the Problems]
  In order to solve the above-mentioned problems, an outdoor unit having a compressor and an outdoor heat exchanger and a plurality of indoor units having an indoor heat exchanger are connected by an inter-unit pipe having a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe. A first on-off valve connected between one end of each indoor heat exchanger and the high-pressure gas pipe; and a first on-off valve arranged between one end of each indoor heat exchanger and the low-pressure gas pipe. An air conditioner configured to have two open / close valves and a refrigerant pressure reducer disposed between the other end of each indoor heat exchanger and the liquid pipe so that each indoor unit can perform a cooling operation or a heating operation. In the apparatus, a first temperature sensor is provided on one end side of the indoor heat exchanger of each indoor unit, a second temperature sensor is provided on the other end side, and when the indoor unit is switched from heating operation to cooling operation, The first on-off valve, the second on-off valve and the indoor unit side And closing means for closing the refrigerant pressure reducer,After closing the first on-off valve, the second on-off valve and the refrigerant pressure reducer by this closing means, a first predetermined time sufficiently long that the refrigerant pressure in the indoor heat exchanger becomes the saturation pressure has elapsed. If before starting the cooling operation,Opening means for opening the second on-off valve closed by the closing means;Before the first predetermined time elapses, the temperature difference between the temperature detected by the first temperature sensor of the indoor unit and the temperature detected by the second temperature sensor becomes equal to or lower than the first predetermined value. A time-up means for forcibly time-up the timer for measuring the first predetermined time and opening the second on-off valve by the opening means;It is characterized by comprising.
[0009]
In this case, the temperature difference between the temperature detected by the first temperature sensor of the indoor unit and the current temperature detected by the first temperature sensor of the indoor unit immediately before opening the second on-off valve by the opening means. However, when the indoor heat exchanger of the indoor unit and the low-pressure gas pipe become equal to or more than a second predetermined value at which the pressure is almost equalized, there may be provided means for starting the cooling operation.
[0010]
  In this case,The temperature difference between the temperature detected by the first temperature sensor of the indoor unit and the current temperature detected by the first temperature sensor of the indoor unit immediately before opening the second on-off valve by the opening means is the indoor unit. The indoor heat exchanger and the low-pressure gas pipe are in a substantially equal pressure state.If the second predetermined time long enough for the indoor heat exchanger and the low-pressure gas pipe to be approximately equalized before the second predetermined value is reached, the cooling operation is started. May be.
[0011]
  In addition, an outdoor unit having a compressor and an outdoor heat exchanger, and a plurality of indoor units having an indoor heat exchanger are connected by an inter-unit pipe having a high pressure gas pipe, a low pressure gas pipe, and a liquid pipe. A first on-off valve disposed in a high-pressure gas branch pipe connecting one end of the heat exchanger and the high-pressure gas pipe; and a low-pressure gas branch pipe connecting the one end of each indoor heat exchanger and the low-pressure gas pipe A second open / close valve disposed; a refrigerant decompressor disposed between the other end of each indoor heat exchanger and the liquid pipe; and a low-pressure gas branch pipe connected in parallel to the low-pressure gas branch pipe. And an air conditioner configured to perform a cooling operation or a heating operation for each indoor unit in the air conditioner having the third on-off valve disposed in the bypass pipe having a large flow path resistance. A first temperature sensor is provided on one end side of the vessel, A second temperature sensor is provided on the end side, and when the indoor unit is switched from the heating operation to the cooling operation, the first on-off valve, the second on-off valve, the third on-off valve, and the refrigerant decompressor on the indoor unit side are closed. Closure means;The first on / off valve, the second on / off valve, the third on / off valve, and the refrigerant pressure reducer are closed by the closing means, and the first pressure is long enough for the refrigerant pressure in the indoor heat exchanger to reach the saturation pressure. When the predetermined time has elapsed, before starting the cooling operation, the opening unit that opens the third on-off valve closed by the closing unit, and the indoor unit before the first predetermined time elapses When the temperature difference between the temperature detected by the first temperature sensor and the temperature detected by the second temperature sensor is equal to or lower than the first predetermined value, the timer for counting the first predetermined time is forcibly set. Time-up means for opening the third on-off valve by the opening means.It is characterized by comprising.
[0012]
In this case, the temperature difference between the temperature detected by the first temperature sensor of the indoor unit and the current temperature detected by the first temperature sensor of the indoor unit immediately before opening the third on-off valve by the opening means. However, when the indoor heat exchanger of the indoor unit and the low pressure gas pipe become equal to or higher than a second predetermined value at which the pressure is almost equalized, the second on-off valve closed by the closing means is opened, A means for starting operation is provided.
[0013]
  In this case,The difference between the temperature detected by the first temperature sensor of the indoor unit and the current temperature detected by the first temperature sensor of the indoor unit immediately before opening the third on-off valve by the opening means is the indoor unit. The indoor heat exchanger and the low-pressure gas pipe are in a substantially equalized state before the indoor heat exchanger and the low-pressure gas pipe are equal to or greater than a second predetermined value that is in a substantially equalized state.When the second predetermined time sufficiently long is passed, the means for starting the cooling operation may open the second on-off valve closed by the closing means and start the cooling operation.
[0014]
  In addition, an outdoor unit having a compressor and an outdoor heat exchanger, and a plurality of indoor units having an indoor heat exchanger are connected by an inter-unit pipe having a high pressure gas pipe, a low pressure gas pipe, and a liquid pipe. A first on-off valve disposed between one end of a heat exchanger and the high-pressure gas pipe; a second on-off valve disposed between one end of each indoor heat exchanger and the low-pressure gas pipe; In a control method of an air conditioner having a refrigerant pressure reducer disposed between the other end of each indoor heat exchanger and the liquid pipe, and configured to perform cooling operation or heating operation for each indoor unit Closing the first on-off valve, the second on-off valve and the refrigerant pressure reducer on the indoor unit side when switching the indoor unit from the heating operation to the cooling operation;In this closing process, a first predetermined time sufficiently long that the refrigerant pressure in the indoor heat exchanger becomes the saturation pressure has elapsed since the first on-off valve, the second on-off valve, and the refrigerant pressure reducer are closed. In this case, before starting the cooling operation, the opening process of opening the second on-off valve closed in the closing process, and the indoor heat exchanger of the indoor unit before the first predetermined time elapses. When the temperature difference between the temperature at one end and the temperature at the other end is equal to or lower than a first predetermined value, a timer for measuring the first predetermined time is forcibly timed up, and the opening process is performed. And a time-up process for opening the second on-off valve;It is characterized by comprising.
[0015]
In this case, the difference between the temperature at one end of the indoor heat exchanger of the indoor unit immediately before opening the second on-off valve in the opening process and the current temperature at one end of the indoor heat exchanger of the indoor unit. When the temperature is equal to or higher than a second predetermined value at which the indoor heat exchanger of the indoor unit and the low-pressure gas pipe are in a substantially equalized state, a process of starting a cooling operation is provided. It is.
[0016]
  In this case,SaidIn the opening process, the temperature difference between the temperature at one end of the indoor heat exchanger of the indoor unit immediately before opening the second on-off valve and the current temperature at one end of the indoor heat exchanger of the indoor unit is the room temperature. The unit's indoor heat exchanger and the low-pressure gas pipe are in an approximately equal pressure state.The cooling operation is started when a second predetermined time sufficient for the indoor heat exchanger and the low-pressure gas pipe to be in a substantially equalized state has elapsed before the second predetermined value or more is reached. You may move on to the process.
[0017]
  In addition, an outdoor unit having a compressor and an outdoor heat exchanger, and a plurality of indoor units having an indoor heat exchanger are connected by an inter-unit pipe having a high pressure gas pipe, a low pressure gas pipe, and a liquid pipe. A first on-off valve disposed in a high-pressure gas branch pipe connecting one end of the heat exchanger and the high-pressure gas pipe; and a low-pressure gas branch pipe connecting the one end of each indoor heat exchanger and the low-pressure gas pipe A second open / close valve disposed; a refrigerant decompressor disposed between the other end of each indoor heat exchanger and the liquid pipe; and a low-pressure gas branch pipe connected in parallel to the low-pressure gas branch pipe. And a third on-off valve disposed in a bypass pipe having a large flow path resistance. In the control method of an air conditioner configured to perform cooling operation or heating operation for each indoor unit, the indoor unit is heated. When switching from operation to cooling operation, Knit side first on-off valve, the second on-off valve, a closing operation for closing the third on-off valve and the refrigerant pressure reducer,In this closing process, the first on-off valve, the second on-off valve, the third on-off valve, and the refrigerant pressure reducer are closed, and then the first enough of the refrigerant pressure in the indoor heat exchanger becomes the saturation pressure. When the predetermined time has elapsed, before starting the cooling operation, the indoor unit is opened before the first predetermined time elapses, and the opening process of opening the third on-off valve closed in the closing process. When the difference between the temperature at one end of the indoor heat exchanger and the temperature at the other end of the indoor heat exchanger is equal to or lower than a first predetermined value, the timer for counting the first predetermined time is forcibly timed up. And a time-up process for shifting to the opening process and opening the third on-off valve.
[0018]
In this case, the difference between the temperature at one end of the indoor heat exchanger of the indoor unit immediately before opening the third on-off valve in the opening process and the current temperature at one end of the indoor heat exchanger of the indoor unit. When the temperature is equal to or higher than a second predetermined value at which the indoor heat exchanger of the indoor unit and the low-pressure gas pipe are in a substantially equalized state, the second on-off valve closed in the closing process is opened, A process of starting the cooling operation may be provided.
[0019]
  In this case,In the opening process, the temperature difference between the temperature at one end of the indoor heat exchanger of the indoor unit immediately before opening the third on-off valve and the current temperature at one end of the indoor heat exchanger of the indoor unit is the room temperature. Before the indoor heat exchanger of the unit and the low-pressure gas pipe reach a second predetermined value or more that is in a substantially equal pressure state, the indoor heat exchanger and the low-pressure gas pipe are sufficient to be in a substantially equal pressure state. Of lengthWhen the second predetermined time has elapsed, the process may be shifted to a process of starting the cooling operation, and the second on-off valve closed in the closing process may be opened to start the cooling operation.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a refrigerant circuit diagram showing an embodiment of an air-conditioning apparatus according to the present invention. The air conditioner 50 includes an outdoor unit 1 and a plurality of (for example, two in FIG. 1) indoor units 2a and 2b.
[0022]
The outdoor unit 1 includes a compressor 3 and an outdoor heat exchanger 4. An outdoor fan 5 is disposed adjacent to the outdoor heat exchanger 4. The compressor 3 is driven by a gas engine (not shown), for example. The outdoor heat exchanger 4 includes a plurality of (for example, two) outdoor heat exchangers 4a and 4b, and the outdoor heat exchangers 4a and 4b are connected in parallel. For example, the outdoor heat exchanger 4a and the outdoor heat exchanger 4b have different heat exchange capacities (heat exchange capacities).
[0023]
The indoor units 2a and 2b include indoor heat exchangers 6a and 6b and indoor electronic expansion valves 18a and 18b as refrigerant decompressors. The indoor fans 9a and 9b are respectively disposed adjacent to the indoor heat exchangers 6a and 6b.
[0024]
And these outdoor unit 1 and indoor unit 2a, 2b are connected by the inter-unit piping 10 which has the high pressure gas pipe 11, the low pressure gas pipe 12, and the liquid pipe 13, and the air conditioning apparatus 50 is the indoor unit 2a, 2b can be simultaneously operated for cooling or heating, or can be implemented by mixing these cooling and heating operations. That is, the indoor unit 2a, 2b is configured to perform a cooling operation or a heating operation.
[0025]
In the outdoor unit 1, one end of the outdoor heat exchanger 4 is alternatively branched and connected to the refrigerant discharge pipe 7 and the refrigerant suction pipe 8 of the compressor 3.
[0026]
Specifically, one end of the outdoor heat exchanger 4a is connected to the refrigerant discharge pipe 7 of the compressor 3 via the switching valve 21a, and is connected to the refrigerant suction pipe 8 of the compressor 3 via the switching valve 22a. Is done. One end of the outdoor heat exchanger 4b is connected to the refrigerant discharge pipe 7 of the compressor 3 via the switching valve 21b, and is connected to the refrigerant suction pipe 8 of the compressor 3 via the switching valve 22b.
[0027]
The high-pressure gas pipe 11 of the inter-unit pipe 10 is connected to the refrigerant discharge pipe 7. The low pressure gas pipe 12 is connected to the refrigerant suction pipe 8. The liquid pipe 13 is connected to the other end of each of the outdoor heat exchangers 4a and 4b via a receiver tank 26 and outdoor electronic expansion valves 27a and 27b as auxiliary refrigerant decompressors.
[0028]
The refrigerant suction pipe 8 is provided with an accumulator 24, and the refrigerant discharge pipe 7 is provided with an oil separator 25. Further, a high / low pressure bypass valve 23 that bypasses the refrigerant discharge pipe 7 and the refrigerant suction pipe 8 is provided.
[0029]
The indoor heat exchangers 6a and 6b of the indoor units 2a and 2b respectively have a liquid branch pipe 19a provided with an indoor electronic expansion valve 18a and a liquid branch pipe provided with an indoor electronic expansion valve 18b at the other end. Each is connected to the liquid pipe 13 via 19b.
[0030]
One end of the indoor heat exchanger 6a of the indoor unit 2a is connected to the high-pressure gas pipe 11 via the high-pressure gas branch pipe 14a and to the low-pressure gas pipe 12 via the low-pressure gas branch pipe 15a. Is done. One end of the indoor heat exchanger 6b of the indoor unit 2b is connected to the high pressure gas pipe 11 via the high pressure gas branch pipe 14b and to the low pressure gas pipe 12 via the low pressure gas branch pipe 15b. The
[0031]
First on-off valves (first electromagnetic on-off valves) 16a and 16b are disposed in the high-pressure gas branch pipes 14a and 14b, respectively. In addition, second on-off valves (second electromagnetic on-off valves) 17a and 17b are disposed in the low-pressure gas branch pipes 15a and 15b, respectively.
[0032]
The low pressure gas branch pipes 15a and 15b are connected in parallel with first bypass pipes 28a and 28b and second bypass pipes 29a and 29b that bypass the second on-off valves 17a and 17b.
[0033]
Third on-off valves (third electromagnetic on-off valves) 30a and 30b are disposed in the first bypass pipes 28a and 28b, respectively. In addition, fourth on-off valves (fourth electromagnetic on-off valves) 31a and 31b are disposed in the second bypass pipes 29a and 29b, respectively.
[0034]
The first bypass pipes 28a and 28b and the second bypass pipes 29a and 29b have a smaller diameter than the low-pressure gas branch pipes 15a and 15b, thereby increasing the refrigerant flow resistance than the low-pressure gas branch pipes 15a and 15b. ing.
[0035]
The first on-off valves 16a and 16b, the second on-off valves 17a and 17b, the third on-off valves 30a and 30b, and the fourth on-off valves 31a and 31b are respectively stored in the electromagnetic valve units 20a and 20b.
[0036]
First temperature sensors 43a and 43b for detecting the temperature of the refrigerant are provided on one end side (the refrigerant outlet side when acting as an evaporator) of the indoor heat exchangers 6a and 6b of the indoor units 2a and 2b. ing. In addition, second temperature sensors 44a and 44b for detecting the temperature of the refrigerant are provided on the other end side (the refrigerant inlet side when acting as an evaporator) of the indoor heat exchangers 6a and 6b of the indoor units 2a and 2b. Is provided. That is, the first temperature sensors 43a and 43b detect the temperature of the gas refrigerant in the indoor heat exchangers 6a and 6b, and the second temperature sensors 44a and 44b detect the temperature of the liquid refrigerant.
[0037]
The outdoor unit 1 is provided with an outdoor control device 41 that controls the outdoor unit 1. Each indoor unit 2a, 2b is provided with indoor control devices 42a, 42b for controlling the indoor units 2a, 2b. The indoor control devices 42a and 42b are connected to the outdoor control device 41 via a communication line.
[0038]
Each of the indoor control devices 42a and 42b acquires the temperature detected by the first temperature sensors 43a and 43b and the temperature detected by the second temperature sensors 44a and 44b. These detection results are transmitted to the outdoor control device 41. Further, each of the indoor control devices 42a and 42b is configured so that the valve opening degree of the indoor electronic expansion valves 18a and 18b, the electromagnetic valve units 20a and 20b (that is, the first on-off valve) is based on the command transmitted by the outdoor control device 41. 16a, 16b, second on-off valves 17a, 17b, third on-off valves 30a, 30b and fourth on-off valves 31a, 31b), and the number of revolutions of the indoor fans 9a, 9b are controlled.
[0039]
The outdoor control device 41 transmits a command for controlling the indoor electronic expansion valves 18a and 18b, the electromagnetic valve units 20a and 20b, the indoor fans 9a and 9b, and the like to the indoor control devices 42a and 42b. In addition, the outdoor control device 41 is configured such that the opening degree of the outdoor electronic expansion valves 27a and 27b, the opening and closing of the switching valves 21a, 22a, 21b, and 22b, the rotational speed of the outdoor fan 5, the opening degree of the high / low pressure bypass valve 23, and the like. To control.
[0040]
The outdoor control device 41 and the indoor control devices 42a and 42b control the entire air conditioner 50.
[0041]
The opening degree of the outdoor electronic expansion valves 27a and 27b and the indoor electronic expansion valves 18a and 18b are adjusted by, for example, a stepping motor (not shown). For example, the pulse (step) input to the stepping motor is set to be fully closed when, for example, 20 steps are fully opened when it is 480 steps.
[0042]
The indoor control devices 42a and 42b have first on-off valves 16a and 16b, second on-off valves 17a and 17b, and third on-off valve 30a according to an operation mode (cooling operation or heating operation) set by a remote controller (not shown). , 30b and the fourth on-off valves 31a, 31b. And the indoor control apparatuses 42a and 42b transmit the signal containing the setting information of the remote controller of the indoor units 2a and 2b to the outdoor control apparatus 41.
[0043]
Next, the driving operation will be described.
[0044]
(A) When all the indoor units 2a and 2b are operated for cooling at the same time, the high-pressure gas pipe 11 is put into a resting state.
[0045]
In this case, while opening one switching valve 21a, 21b of the outdoor heat exchangers 4a, 4b and closing the other switching valve 22a, 22b, and closing the first on-off valves 16a, 16b of the electromagnetic valve units 20a, 20b, The second on-off valves 17a and 17b, the third on-off valves 30a and 30b, and the fourth on-off valves 31a and 31b are opened.
[0046]
Thus, the refrigerant discharged from the compressor 3 sequentially flows to the refrigerant discharge pipe 7, the oil separator 25, the switching valves 21a and 21b, and the outdoor heat exchangers 4a and 4b, and is condensed and liquefied by the outdoor heat exchangers 4a and 4b. To do. The condensed and liquefied refrigerant passes through the outdoor electronic expansion valves 27a and 27b and the receiver tank 26, and is distributed to the indoor electronic expansion valves 18a and 18b of the chamber units 2a and 2b via the liquid pipe 13 and the liquid branch pipes 19a and 19b. , Where the pressure is reduced.
[0047]
Thereafter, the refrigerant decompressed by the indoor electronic expansion valves 18a and 18b evaporates and evaporates in the indoor heat exchangers 6a and 6b, and then the second on-off valves 17a and 17b, the third on-off valves 30a and 30b, and the fourth, respectively. After the on-off valves 31a and 31b flow in parallel, they are sucked into the compressor 3 through the low-pressure gas pipe 12, the refrigerant suction pipe 8, and the accumulator 24 in this order.
[0048]
In this way, all the indoor units 2a and 2b are simultaneously cooled in the indoor heat exchangers 6a and 6b acting as evaporators.
[0049]
(B) When heating all the indoor units 2a and 2b simultaneously, the low-pressure gas pipe 12 is put into a resting state.
[0050]
In this case, while closing one switching valve 21a, 21b of the outdoor heat exchangers 4a, 4b and opening the other switching valve 22a, 22b, and opening the first on-off valves 16a, 16b of the electromagnetic valve units 20a, 20b, The second on-off valves 17a and 17b, the third on-off valves 30a and 30b, and the fourth on-off valves 31a and 31b are closed.
[0051]
Thereby, the refrigerant discharged from the compressor 3 is distributed to the high-pressure gas branch pipes 14a and 14b through the refrigerant discharge pipe 7, the oil separator 25, and the high-pressure gas pipe 11 in order, and then the first on-off valves 16a and 16b, It flows to the indoor heat exchangers 6a and 6b, where it condensates.
[0052]
The condensed and liquefied refrigerant is decompressed by the indoor electronic expansion valves 18a and 18b, and is merged by the liquid pipe 13 through the liquid branch pipes 19a and 19b.
[0053]
Thereafter, the liquid refrigerant in the liquid pipe 13 passes through the receiver tank 26 and the outdoor electronic expansion valves 27a and 27b and evaporates and evaporates in the outdoor heat exchangers 4a and 4b. Then, the switching valves 22a and 22b, the refrigerant suction pipe 8, The air is sucked into the compressor 3 through the accumulator 24 sequentially. Thus, in each indoor heat exchanger 6a, 6b acting as a condenser, all the indoor units 2a, 2b are simultaneously heated.
[0054]
(C) Next, for example, when the indoor unit 2a is cooled and the indoor unit 2b is heated, all the refrigerant pipes 11, 12, and 13 are used. First, the case where the cooling load on the indoor unit 2a side is larger than the heating load on the indoor unit 2b side will be described.
[0055]
In this case, one of the switching valves 21a and 21b of the outdoor heat exchangers 4a and 4b is opened and the other switching valves 22a and 22b are closed, and the first on-off valve 16a in the electromagnetic valve unit 20a of the indoor unit 2a that is in the cooling operation. Is opened, the second on-off valve 17a, the third on-off valve 30a and the fourth on-off valve 31a are opened, and the first on-off valve 16b in the electromagnetic valve unit 20b of the indoor unit 2b to be heated is opened, and the second on-off valve is opened. The valve 17b, the third on-off valve 30b, and the fourth on-off valve 31b are closed.
[0056]
Then, a part of the refrigerant discharged from the compressor 3 and passing through the refrigerant discharge pipe 7 and the oil separator 25 flows to the outdoor heat exchangers 4a and 4b via the switching valves 21a and 21b, and the remaining refrigerant is high-pressure gas. It flows through the pipe 11 to the first on-off valve 16b and the indoor heat exchanger 6b in the electromagnetic valve unit 20b of the indoor unit 2b that performs the heating operation. Thereby, it is condensed and liquefied by the indoor heat exchanger 6b and the outdoor heat exchangers 4a and 4b.
[0057]
Then, the refrigerant condensed and liquefied by the indoor heat exchanger 6b and the outdoor heat exchangers 4a and 4b is decompressed by the indoor electronic expansion valve 18a of the indoor unit 2a via the liquid pipe 13, and then is cooled by the indoor heat exchanger 6a. It is evaporated. Thereafter, the refrigerant flows through the second on-off valve 17a, the third on-off valve 30a, and the fourth on-off valve 31a in parallel and is joined by the low-pressure gas pipe 12, and is sucked into the compressor 3 through the refrigerant suction pipe 8 and the accumulator 24 in order. Is done. In this way, the indoor unit 2b is heated by the indoor heat exchanger 6b that acts as a condenser, and the indoor unit 2a is cooled by the indoor heat exchanger 6a that acts as an evaporator.
[0058]
Next, a case where the heating load on the indoor unit 2b side is larger than the cooling load on the indoor unit 2a side will be described.
[0059]
In this case, the first switching valve 21a, 21b of the outdoor heat exchanger 4a, 4b is closed and the other switching valve 22a, 22b is opened, and the first on-off valve in the electromagnetic valve unit 20a of the indoor unit 2a that is in the cooling operation. 16a is closed, the second on-off valve 17a, the third on-off valve 30a and the fourth on-off valve 31a are opened, and the first on-off valve 16b in the electromagnetic valve unit 20b of the indoor unit 2b to be heated is opened, and the second The on-off valve 17b, the third on-off valve 30b, and the fourth on-off valve 31b are closed.
[0060]
Then, the refrigerant discharged from the compressor 3 sequentially passes through the refrigerant discharge pipe 7 and the high-pressure gas pipe 11, passes through the first on-off valve 16b, and is condensed and liquefied in the indoor heat exchanger 6b.
[0061]
The liquefied refrigerant flows into the liquid pipe 13 through the fully opened indoor electronic expansion valve 18b. A part of the liquid refrigerant in the liquid pipe is decompressed by the indoor electronic expansion valve 18a and then the indoor heat exchanger 6b, and the remaining liquid refrigerant is decompressed by the outdoor electronic expansion valves 27a and 27b and the outdoor heat. The gas is evaporated and vaporized by the exchangers 4a and 4b, and sucked into the compressor 3 through the refrigerant suction pipe 8 and the accumulator 24 in order. In this way, the indoor unit 2b is heated by the indoor heat exchanger 6b that acts as a condenser, and the indoor unit 2a is cooled by the indoor heat exchanger 6a that acts as an evaporator.
[0062]
As described above, when the cooling load of the indoor units 2a and 2b performing the cooling operation is larger than the heating load of the indoor units 2a and 2b performing the heating operation, the outdoor heat exchangers 4a and 4b are caused to act as condensers. On the other hand, when the cooling load of the indoor units 2a and 2b to be cooled is smaller than the heating load of the indoor units 2a and 2b to be heated, the outdoor heat exchangers 4a and 4b are caused to act as evaporators. By these, arbitrary indoor units 2a and 2b can be freely cooled and heated.
[0063]
In the operation states shown in the above (A) to (C), when the difference between the cooling load and the heating load of the indoor units 2a and 2b is smaller than a predetermined value, the outdoor control device 41 sets the outdoor heat exchanger 4a or 4b. Control to pause. When the outdoor heat exchanger 4a is suspended, the outdoor control device 41 controls the outdoor electronic expansion valve 27a to be fully closed and performs control to close the switching valves 21a and 22a. When the outdoor heat exchanger 4b is suspended, the outdoor control device 41 controls the outdoor electronic expansion valve 27b to be fully closed and performs control to close the switching valves 21b and 22b.
[0064]
Further, in the operation state shown in (C) above, when the cooling load and the heating load of the indoor units 2a and 2b are the same, the outdoor control device 41 causes the outdoor electronic expansion to stop the outdoor heat exchangers 4a and 4b. The valves 27a and 27b are controlled to be fully closed, and the switching valves 21, 22a, 21b and 22b are controlled to be closed.
[0065]
In the present embodiment, when the indoor unit (for example, 2a) is switched from the heating operation to the cooling operation during the above operation, for example, the indoor unit 2a is switched from the heating operation to the cooling operation by a remote controller (not shown). In this case, the outdoor control device 41 and the indoor control device 42a perform control to prevent refrigerant noise generated from the indoor unit 2a. Since the indoor unit 2b operates in the same manner as the indoor unit 2a, the description of the operation of the indoor unit 2b is omitted.
[0066]
Hereinafter, control operations of the outdoor control device 41 and the indoor control device 42a will be described with reference to the flowchart shown in FIG.
[0067]
First, the outdoor control device 41 determines the operation mode of the indoor units 2a and 2b (step S1). For example, when the indoor unit 2a is switched from the heating operation to the cooling operation, the indoor control device 42a receives the electromagnetic of the indoor unit 2a. An indoor control device that transmits a command to close (closes) the first on-off valve 16a, the second on-off valve 17a, the third on-off valve 30a, and the fourth on-off valve 31a of the valve unit 20a, and receives the instruction 42a controls closing of the first on-off valve 16a, the second on-off valve 17a, the third on-off valve 30a, and the fourth on-off valve 31a of the electromagnetic valve unit 20a (step S2).
[0068]
Further, the outdoor control device 41 transmits a command to close (fully close) the indoor electronic expansion valve 18a to the indoor control device 42a, and the indoor control device 42a that has received this command fully closes the indoor electronic expansion valve 18a. Control (step S3). Specifically, the outdoor control device 41 transmits a command to the indoor control device 42a to set a stepping motor (not shown) of the indoor electronic expansion valve 18a to 20 steps, and the indoor control device 42a that has received this command receives the command. Then, control is performed to set a stepping motor (not shown) of the indoor electronic expansion valve 18a to 20 steps.
[0069]
Before performing the operations of steps S2 and S3, that is, before closing the first on-off valve 16a, the second on-off valve 17a, the third on-off valve 30a, the fourth on-off valve 31a, and the indoor electronic expansion valve 18a of the electromagnetic valve unit 20a. Since the heating operation is performed in the indoor unit 2a, there is a pressure difference between the refrigerant pressure on one end side and the refrigerant pressure on the other end side of the indoor heat exchanger 6a. At this time, the pressure on one end side of the indoor heat exchanger 6a is higher than the pressure on the other end side of the indoor heat exchanger 6a. When the first on-off valve 16a, the second on-off valve 17a, the third on-off valve 30a, the fourth on-off valve 31a, and the indoor electronic expansion valve 18a of the electromagnetic valve unit 20a are closed in steps S2 and S3, the indoor heat exchanger In 6a, the pressure difference (temperature difference) gradually decreases so as to be in an equilibrium state (saturation pressure). Further, the pressure (temperature) of the refrigerant in the indoor heat exchanger 6a gradually decreases due to the heat radiation action.
[0070]
Accordingly, the outdoor control device 41 closes the first on-off valve 16a, the second on-off valve 17a, the third on-off valve 30a, the fourth on-off valve 31a, and the indoor electronic expansion valve 18a of the electromagnetic valve unit 20a by a timer (not shown). Then, timing is started (step S4). At this time, the timer is set to time until a first predetermined time T1 (for example, 120 [sec]) long enough for the refrigerant pressure in the indoor heat exchanger 6a to reach the saturation pressure. Yes.
[0071]
Next, the outdoor control device 41 determines whether or not the first predetermined time T1 has elapsed (step S5).
[0072]
When the first predetermined time T1 has not elapsed (step S5; No), the outdoor control device 41 determines the difference between the temperature detected by the first temperature sensor 43a and the temperature detected by the second temperature sensor 44a. The temperature Tdn is calculated (step S6). In other words, the outdoor control device 41 calculates the temperature difference Tdn between the temperature at one end of the indoor heat exchanger 6a (gas refrigerant temperature) and the temperature at the other end of the indoor heat exchanger 6a (liquid refrigerant temperature). Yes.
[0073]
Next, the outdoor control device 41 determines whether or not this differential temperature Tdn is equal to or lower than a first predetermined value (for example, 20 [K]) at which the refrigerant pressure in the indoor heat exchanger 6a is close to the saturation pressure. Is discriminated (step S7; first discriminating means).
[0074]
When the temperature difference Tdn is equal to or lower than the first predetermined value (step S7; Yes), the outdoor control device 41 forcibly times up a timer (not shown) (step S8), and proceeds to the determination of step S5.
[0075]
That is, when the temperature difference Tdn is equal to or lower than the first predetermined value, the refrigerant pressure in the indoor heat exchanger 6a is close to the saturation pressure, so there is no need to wait for the first predetermined time T1 to elapse. .
[0076]
When the temperature difference Tdn is not equal to or lower than the first predetermined value, that is, when the temperature difference Tdn is larger than the first predetermined value (step S7; No), the process proceeds to the determination of step S5.
[0077]
In step S5, when the temperature difference Tdn is equal to or lower than the first predetermined value, or the first on-off valve 16a, the second on-off valve 17a, the third on-off valve 30a, the fourth on-off valve 31a, and the indoor electronics When the first predetermined time T1 has elapsed since the expansion valve 18a was closed, in other words, when the time of a timer (not shown) has expired (step S5; Yes), the outdoor control device 41 The temperature (gas refrigerant temperature of the indoor heat exchanger 6a) Tg1 detected by the temperature sensor 43a is stored (step S9; storage means).
[0078]
Here, even if the first predetermined time T1 (for example, 120 [sec]) has elapsed and the temperature difference Tdn is greater than the first predetermined value (for example, 20 [K]), The refrigerant in the indoor heat exchanger 6a is sufficiently cooled (depressurized) so that no refrigerant noise is generated when the second on-off valve 17a, the third on-off valve 30a, or the fourth on-off valve 31a of the electromagnetic valve unit 20a is opened. Yes.
[0079]
Even if the temperature sensor 43a, 44a is in a state where a correct value cannot be detected due to an abnormality, if the first predetermined time T1 (for example, 120 [sec]) elapses, the process proceeds to the next step S9. Control stability is improved.
[0080]
Next, a command is transmitted to the indoor control device 42a so that only the third control valve 30a of the electromagnetic valve unit 20a is opened (opened), and the indoor control device 42a that has received this command opens the third control valve 30a. The valve opening control is performed (step S10).
[0081]
That is, in this step S10, the third control valve 30a is controlled to open in order to bring the refrigerant pressure in the indoor heat exchanger 6a closer to the refrigerant pressure in the low-pressure gas pipe 12. In step S10, the third control valve 30a is controlled to open, but the second on-off valve 17a may be controlled to open. This also makes it possible to bring the refrigerant pressure in the indoor heat exchanger 6a closer to the refrigerant pressure in the low-pressure gas pipe 12.
[0082]
In particular, when the third control valve 30a is opened as in step S10, the refrigerant in the indoor heat exchanger 6a is reduced in pressure through the first bypass pipe 28a having a refrigerant flow resistance higher than that of the low-pressure gas branch pipe 15a. Since it will flow to the gas pipe 12 side, generation | occurrence | production of a refrigerant | coolant sound can be suppressed more.
[0083]
Next, the outdoor control device 41 starts timing after closing the third control valve 30a of the electromagnetic valve unit 20a by a timer (not shown) (step S11). At this time, the timer has a second predetermined time that is long enough for the refrigerant pressure in the indoor heat exchanger 6a to drop and the indoor heat exchanger 6a and the low-pressure gas pipe 12 to be in a substantially equalized state. The time is set to T2 (for example, 240 [sec]).
[0084]
Next, the outdoor control device 41 determines whether or not the second predetermined time T2 has elapsed (step S12).
[0085]
When the second predetermined time T2 has not elapsed (step S12; No), the outdoor control device 41 detects the temperature (indoor heat exchanger 6a) detected by the first temperature sensor 43a immediately before opening the third control valve 30a. The temperature difference Tdgn between the gas refrigerant temperature) Tg1 (that is, the stored temperature Tg1) and the current temperature (current gas refrigerant temperature of the indoor heat exchanger 6a) detected by the first temperature sensor 43a is calculated. (Step S13). Specifically, the outdoor control device 41 calculates the absolute value Tdgn of the temperature difference between the stored temperature Tg1 and the current gas refrigerant temperature of the indoor heat exchanger 6a.
[0086]
Here, since the temperature of the one end side of the indoor heat exchanger 6a (gas refrigerant temperature) is opened, since the third on-off valve 30a is opened, the temperature gradually decreases with the lapse of time, and the temperature difference Tdgn gradually increases. It gets bigger.
[0087]
Next, in the outdoor control device 41, is this differential temperature Tdgn greater than or equal to a second predetermined value (for example, 15 [K]) at which the indoor heat exchanger 6a and the low-pressure gas pipe 12 are in a substantially equalized state? It is discriminate | determined (step S14; 2nd discrimination means).
[0088]
When the temperature difference Tdgn is equal to or higher than the second predetermined value (step S14; Yes), the outdoor control device 41 forcibly times up a timer (not shown) (step S15), and proceeds to the determination of step S12.
[0089]
That is, when the differential temperature Tdgn is equal to or higher than the second predetermined value, the indoor heat exchanger 6a and the low-pressure gas pipe 12 are approximately equalized, and it is necessary to wait for the second predetermined time T2 to elapse. Absent.
[0090]
When the differential temperature Tdgn is not equal to or higher than the second predetermined value, that is, when the differential temperature Tdgn is smaller than the second predetermined value (step S14; No), the process proceeds to the determination of step S12.
[0091]
In step S12, when the differential temperature Tdgn becomes equal to or higher than the second predetermined value, or when the second predetermined time T2 has elapsed since the third on-off valve 30a is opened, in other words, a timer (not shown) When the time is up (step S12; Yes), the outdoor control device 41 opens the second on-off valve 17a, transmits a command to the indoor control device 42a to start the cooling operation, and receives the command. The control device 42a performs control to open the second on-off valve 17a and start the cooling operation. When the control for starting the cooling operation is performed, the indoor electronic expansion valve 18a is adjusted to have a valve opening degree corresponding to the cooling load. That is, normal cooling operation is started.
[0092]
Here, even if the second predetermined time T2 (for example, 240 [sec]) has elapsed and the temperature difference Tdgn is smaller than the second predetermined value (for example, 15 [K]), Since the refrigerant pressure in the indoor heat exchanger 6a is sufficiently close to the refrigerant pressure in the low-pressure gas pipe 12, no refrigerant noise is generated even when the cooling operation is started.
[0093]
Even if the temperature sensor 43a, 44a is in a state where a correct value cannot be detected due to an abnormality, if the second predetermined time T2 (for example, 240 [sec]) elapses, the process proceeds to the next step S16. Control stability is improved.
[0094]
With the above operation, when switching from the cooling operation to the heating operation, it is possible to efficiently suppress the generation of refrigerant noise from the indoor unit 2a (in the vicinity of the indoor heat exchanger 6a and the electromagnetic valve unit 20a).
[0095]
As described above, according to the present embodiment, when any one of the indoor units is switched from the heating operation to the cooling operation, the first to fourth on-off valves and the indoor electronic expansion valve of the electromagnetic valve unit on the indoor unit side are closed. Prior to starting the cooling operation, it is determined whether or not the differential temperature Tdn is equal to or lower than the first predetermined value, so that the refrigerant pressure in the indoor heat exchanger 6a accurately becomes the saturation pressure. Therefore, the certainty of suppressing the refrigerant noise of the indoor unit is improved.
[0096]
When the temperature difference Tdn is equal to or lower than the first predetermined value, only the third on-off valve is opened, so that a predetermined time (for example, 60%) is uniformly set after the valve is closed as in the prior art. [Sec]) Compared to waiting for the passage of time, the time for the control operation can be shortened when the temperature difference Tdn is equal to or lower than the first predetermined value in a short time, and the generation of refrigerant noise is more efficiently performed. Can be suppressed. Furthermore, since the time for the control operation can be shortened, the switching time from the heating operation to the cooling operation can be shortened, and the air conditioning performance is improved.
[0097]
Further, according to the present embodiment, it is determined whether or not the differential temperature Tdgn is equal to or greater than a second predetermined value at which the indoor heat exchanger 6a and the low pressure gas pipe 12 are in a substantially equalized state. Since it can be accurately determined whether or not the refrigerant pressure in the indoor heat exchanger 6a is approaching the refrigerant pressure in the low-pressure gas pipe 12, the reliability of suppressing the refrigerant noise of the indoor unit is improved.
[0098]
When the temperature difference Tdgn is equal to or higher than the second predetermined value, the second on-off valve 17a is opened and the normal cooling operation is started. Compared to waiting for the set time (for example, 120 [sec]) to elapse, the time for the control operation can be shortened when the temperature difference Tdgn exceeds the second predetermined value in a short time. Thus, the generation of refrigerant noise can be suppressed more efficiently. Furthermore, since the time for the control operation can be shortened, the switching time from the heating operation to the cooling operation can be shortened, and the air conditioning performance is improved.
[0099]
As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this.
[0100]
For example, in the above embodiment, the low pressure gas branch pipes 15a and 15b are connected in parallel to the second bypass pipes 29a and 29b provided with the fourth on-off valves 31a and 31b that bypass the second on-off valves 17a and 17b. However, the fourth on-off valves 31a and 31b and the second bypass pipes 29a and 29b can be omitted.
[0101]
In the above embodiment, the first low-pressure gas branch pipes 15a and 15b are connected in parallel with the first bypass pipes 28a and 28b provided with the third on-off valves 30a and 30b that bypass the second on-off valves 17a and 17b. However, the third on-off valves 30a and 30b and the first bypass pipes 28a and 28b can be omitted. In this case, in step S10 shown in FIG. 2, only the second on-off valve is controlled to open. This also brings about an effect that the generation of refrigerant noise can be efficiently suppressed, as in the above embodiment.
[0102]
In the above embodiment, the case where the third on-off valve 30a is opened in step S10 has been described. However, the flow resistance is lower than that of the low-pressure gas branch pipe connected in parallel to the low-pressure gas branch pipe provided with the second on-off valve. For example, the fourth on-off valve 31a may be opened.
[0103]
【The invention's effect】
According to the present invention, it is possible to efficiently suppress the generation of refrigerant noise.
[Brief description of the drawings]
FIG. 1 is a refrigerant circuit diagram showing an embodiment of an air conditioner according to the present invention.
FIG. 2 is a flowchart showing a control operation when switching from a heating operation to a cooling operation.
[Explanation of symbols]
1 outdoor unit
2a, 2b Indoor unit
3 Compressor
4 outdoor heat exchangers
10 Inter-unit piping
11 High-pressure gas pipe
12 Low pressure gas pipe
13 Liquid pipe
14a, 14b High-pressure gas branch pipe
15a, 15b Low pressure gas branch pipe
16a, 16b first on-off valve
17a, 17b Second on-off valve
18a, 18b Indoor electronic expansion valve (refrigerant decompressor)
19a, 19b Liquid branch pipe
20a, 20b Solenoid valve unit
28a, 28b First bypass pipe (bypass pipe)
30a, 30b 3rd on-off valve
41 Outdoor control device (closing means, opening means)
42a, 42b Indoor control device (closing means, opening means)
43a, 43b first temperature sensor
44a, 44b Second temperature sensor

Claims

An outdoor unit having a compressor and an outdoor heat exchanger and a plurality of indoor units having an indoor heat exchanger are connected by inter-unit piping having a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, and each indoor heat exchange A first on-off valve disposed between one end of the chamber and the high-pressure gas pipe; a second on-off valve disposed between one end of each indoor heat exchanger and the low-pressure gas pipe; In the air conditioner having a refrigerant pressure reducer disposed between the other end of the heat exchanger and the liquid pipe, and configured to perform cooling operation or heating operation for each indoor unit,
A first temperature sensor is provided on one end side of the indoor heat exchanger of each indoor unit, and a second temperature sensor is provided on the other end side,
A closing means for closing the first on-off valve, the second on-off valve and the refrigerant pressure reducer on the indoor unit side when the indoor unit is switched from the heating operation to the cooling operation;
After closing the first on-off valve, the second on-off valve and the refrigerant pressure reducer by this closing means, a first predetermined time sufficiently long that the refrigerant pressure in the indoor heat exchanger becomes the saturation pressure has elapsed. An opening means for opening the second on-off valve closed by the closing means prior to starting the cooling operation ;
Before the first predetermined time elapses, the temperature difference between the temperature detected by the first temperature sensor of the indoor unit and the temperature detected by the second temperature sensor becomes equal to or lower than the first predetermined value. In this case, the air conditioner further comprises time-up means for forcibly time-up the timer for measuring the first predetermined time and opening the second on-off valve by the opening means .

In the air conditioning apparatus according to claim 1,
The difference between the temperature detected by the first temperature sensor of the indoor unit and the current temperature detected by the first temperature sensor of the indoor unit immediately before opening the second on-off valve by the opening means is the room temperature. An air conditioner comprising means for starting a cooling operation when the indoor heat exchanger of the unit and the low-pressure gas pipe become equal to or greater than a second predetermined value at which the pressure is almost equalized.

In the air conditioning apparatus according to claim 2,
Temperature difference is, the indoor current and temperature detected by the first temperature sensor temperature and the indoor unit detected by the first temperature sensor of the indoor unit just prior to opening the second on-off valve by the opening means Before the indoor heat exchanger of the unit and the low-pressure gas pipe reach a second predetermined value or more that is in a substantially equal pressure state , the indoor heat exchanger and the low-pressure gas pipe are sufficient to be in a substantially equal pressure state. Starting a cooling operation when a second predetermined time of length has elapsed;
An air conditioner characterized by.

An outdoor unit having a compressor and an outdoor heat exchanger and a plurality of indoor units having an indoor heat exchanger are connected by inter-unit piping having a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, and each indoor heat exchange A first on-off valve disposed in a high-pressure gas branch pipe that connects one end of the chamber and the high-pressure gas pipe; and a low-pressure gas branch pipe that connects one end of each indoor heat exchanger and the low-pressure gas pipe A second on-off valve, a refrigerant decompressor disposed between the other end of each indoor heat exchanger and the liquid pipe, and a parallel connection to the low-pressure gas branch pipe and a flow from the low-pressure gas branch pipe. In an air conditioner having a third on-off valve disposed in a bypass pipe having a large road resistance, and configured to perform cooling operation or heating operation for each indoor unit,
A first temperature sensor is provided on one end side of the indoor heat exchanger of each indoor unit, and a second temperature sensor is provided on the other end side,
A closing means for closing the first on-off valve, the second on-off valve, the third on-off valve and the refrigerant pressure reducer on the indoor unit side when switching the indoor unit from the heating operation to the cooling operation;
The first on / off valve, the second on / off valve, the third on / off valve, and the refrigerant pressure reducer are closed by the closing means, and the first pressure is long enough for the refrigerant pressure in the indoor heat exchanger to reach the saturation pressure. An opening means for opening the third on-off valve closed by the closing means before starting the cooling operation when the predetermined time has elapsed;
Before the first predetermined time elapses, the temperature difference between the temperature detected by the first temperature sensor of the indoor unit and the temperature detected by the second temperature sensor becomes equal to or lower than the first predetermined value. In this case, the air conditioner further comprises time-up means for forcibly time-up the timer for measuring the first predetermined time and opening the third on-off valve by the opening means .

In the air conditioning apparatus according to claim 4,
The difference between the temperature detected by the first temperature sensor of the indoor unit and the current temperature detected by the first temperature sensor of the indoor unit immediately before opening the third on-off valve by the opening means is the room temperature. When the indoor heat exchanger of the unit and the low-pressure gas pipe become equal to or higher than a second predetermined value at which the pressure is almost equalized, the second on-off valve closed by the closing means is opened, and the cooling operation is started. An air conditioner comprising a means.

In the air conditioning apparatus according to claim 5,
The difference between the temperature detected by the first temperature sensor of the indoor unit and the current temperature detected by the first temperature sensor of the indoor unit immediately before opening the third on-off valve by the opening means is the room temperature. Before the indoor heat exchanger of the unit and the low-pressure gas pipe reach a second predetermined value or more that is in a substantially equal pressure state, the indoor heat exchanger and the low-pressure gas pipe are sufficient to be in a substantially equal pressure state. The air conditioner characterized in that, when a second predetermined length of time has elapsed, the means for starting the cooling operation opens the second on-off valve closed by the closing means and starts the cooling operation. .

An outdoor unit having a compressor and an outdoor heat exchanger and a plurality of indoor units having an indoor heat exchanger are connected by inter-unit piping having a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, and each indoor heat exchange A first on-off valve disposed between one end of the chamber and the high-pressure gas pipe; a second on-off valve disposed between one end of each indoor heat exchanger and the low-pressure gas pipe; In the control method of the air conditioner having a refrigerant pressure reducer disposed between the other end of the heat exchanger and the liquid pipe, and configured to perform cooling operation or heating operation for each indoor unit,
A closing process of closing the first on-off valve, the second on-off valve and the refrigerant pressure reducer on the indoor unit side when switching the indoor unit from the heating operation to the cooling operation;
In this closing process, a first predetermined time sufficiently long that the refrigerant pressure in the indoor heat exchanger becomes the saturation pressure has elapsed since the first on-off valve, the second on-off valve, and the refrigerant pressure reducer are closed. An opening process of opening the second on-off valve closed in the closing process prior to starting the cooling operation,
When the temperature difference between the temperature at one end of the indoor heat exchanger of the indoor unit and the temperature at the other end becomes equal to or lower than a first predetermined value before the first predetermined time elapses, Control of an air conditioner comprising: a time-up process for forcibly time-up a timer for measuring a predetermined time of 1 to shift to the opening process and open the second on-off valve Method.

In the control method of the air harmony device according to claim 7,
The temperature difference between the temperature at one end of the indoor heat exchanger of the indoor unit immediately before opening the second on-off valve in the opening process and the current temperature at one end of the indoor heat exchanger of the indoor unit is Control of an air conditioner characterized by comprising a process of starting a cooling operation when the indoor heat exchanger of the indoor unit and the low-pressure gas pipe become equal to or higher than a second predetermined value at which the pressure is almost equalized. Method.

In the control method of the air harmony device according to claim 8,
Wherein one end side of the temperature of the indoor heat exchanger of the indoor unit immediately prior to opening the second on-off valve in an open process, the temperature difference between one end of the current temperature of the indoor heat exchanger of the indoor unit, the Before the indoor heat exchanger of the indoor unit and the low-pressure gas pipe reach a second pressure equal to or greater than the second predetermined value, the indoor heat exchanger and the low-pressure gas pipe are sufficient to be in a substantially equal pressure state. When the second predetermined time of a long length has elapsed , the control method of the air conditioner shifts to a process of starting the cooling operation .

An outdoor unit having a compressor and an outdoor heat exchanger and a plurality of indoor units having an indoor heat exchanger are connected by inter-unit piping having a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, and each indoor heat exchange A first on-off valve disposed in a high-pressure gas branch pipe that connects one end of the chamber and the high-pressure gas pipe; and a low-pressure gas branch pipe that connects one end of each indoor heat exchanger and the low-pressure gas pipe A second on-off valve, a refrigerant decompressor disposed between the other end of each indoor heat exchanger and the liquid pipe, and a parallel connection to the low-pressure gas branch pipe and a flow from the low-pressure gas branch pipe. In the control method of an air conditioner having a third on-off valve disposed in a bypass pipe having a large road resistance, and configured to perform cooling operation or heating operation for each indoor unit,
A closing process of closing the first on-off valve, the second on-off valve, the third on-off valve and the refrigerant pressure reducer on the indoor unit side when switching the indoor unit from the heating operation to the cooling operation;
In this closing process, the first on-off valve, the second on-off valve, the third on-off valve, and the refrigerant pressure reducer are closed, and then the first enough of the refrigerant pressure in the indoor heat exchanger becomes the saturation pressure. When the predetermined time has elapsed, prior to starting the cooling operation, an opening process of opening the third on-off valve closed in the closing process;
When the temperature difference between the temperature at one end of the indoor heat exchanger of the indoor unit and the temperature at the other end becomes equal to or lower than a first predetermined value before the first predetermined time elapses, A time-up process in which a timer for measuring a predetermined time of 1 is forcibly timed up, the process proceeds to the opening process, and the third on-off valve is opened.
A control method for an air conditioner, comprising:

In the control method of the air harmony device according to claim 10,
The temperature difference between the temperature at one end of the indoor heat exchanger of the indoor unit immediately before opening the third on-off valve in the opening process and the current temperature at one end of the indoor heat exchanger of the indoor unit is When the indoor heat exchanger of the indoor unit and the low-pressure gas pipe are equal to or higher than a second predetermined value at which the pressure is almost equalized, the second on-off valve closed in the closing process is opened and the cooling operation is started. A method for controlling an air conditioner comprising the step of:

In the control method of the air harmony device according to claim 11,
Wherein the temperature of one end side of the indoor heat exchanger of the indoor unit immediately prior to opening the third on-off valve in an open process, the temperature difference between one end of the current temperature of the indoor heat exchanger of the indoor unit, the Before the indoor heat exchanger of the indoor unit and the low-pressure gas pipe reach a second pressure equal to or greater than the second predetermined value, the indoor heat exchanger and the low-pressure gas pipe are sufficient to be in a substantially equal pressure state. When the second predetermined time of a long length has elapsed, the process proceeds to the process of starting the cooling operation, and the second on-off valve closed in the closing process is opened to start the cooling operation. Control method of air conditioner.